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1. This is not usually useful to do However some systems have a small fixed limit on the size of the environment and putting so much information into the value of MAKEFLAGS can exceed it If you see the error message Arg list too long this may be the problem For strict compliance with POSIX 2 changing MAKEOVERRIDES does not affect MAKEFLAGS if the special target POSIX appears in the makefile You probably do not care about this A similar variable MF LAGS exists also for historical compatibility It has the same value as MAKEFLAGS except that it does not contain the command line variable definitions and it always begins with a hyphen unless it is empty MAKEFLAGS begins with a hyphen only when it begins with an option that has no single letter version such as warn undefined variables MFLAGS was traditionally used explicitly in the recursive make command like this 59 185 5 Writing Commands in Rules ST9 gmake Reference Manual Note 5 6 4 60 185 subsystem cd subdir amp amp MFLAGS but now MAKEFLAGS makes this usage redundant If you want your makefiles to be compatible with old make programs use this technique it will work fine with more modern make versions too The MAKEFLAGS variable can also be useful if you want to have certain options such as k see Section 9 7 Summary of options on page 106 for more info
2. Include another makefile See Section 3 3 Including other makefiles on page 20 RIABLE ride VARIABLE override VARIABLE 4 161 185 Appendix Quick Reference ST9 gmake Reference Manual override VARIABLE VALUE endef Define a variable overriding any previous definition even one from the command line See Section 6 7 The override directive on page 73 export Tell make to export all variables to child processes by default See Section 5 6 2 Communicating variables to a sub make on page 56 export VA export VA export VA export VA export VA unexport VARIABLI Tell make whether or not to export a particular variable to child processes See Section 5 6 2 Communicating variables to a sub make on page 56 vpath PATTERN PATH Specify a search path for files matching a pattern See Sec tion 4 4 2 The vpath directive on page 32 Remove all search paths previously specified for PATT vpath Remove all search paths previously specified in any vpath directive 4 162 185 5 9 gmake Reference Manual Appendix A Quick Reference The following table summarizes the text manipulation functions that GNU make understands subst FROM EXT Replace FROM with in TEXT See Section 8 2 Func tions for string substitution and analysis on page 86 R
3. t 90 addsutfix uiuere e 90 Aseo 117 Archive 00012 133 Archive symbol directories updating sec eee eee diene 134 8 118 D 117 ASFLAGS nint dee ER 119 Assembler programs 11 114 preprocessing 114 Automatic 123 B Desert T 137 basename reinii aeda eere 90 eei 147 Built in target 39 C E 139 C programs COMPING cet epe 113 C programs COMPING 113 et ed 94 Canned command sequences definitig uic ie ente ee 61 ec 117 GEL AG Size E M 119 GO cer a SE Ecce 118 CORLAGS iii 119 Commands echoing t meti ene eet t ee ers 49 AN 62 e ca 5 execution 50 parallel 51 Compilation of a program testing ite tdt 105 Conditional syntax 2 26 Conditionals eee 79 example 00111 79 terii ten 80 ttiat test oce 82 118 CPPELAGS utente eM 119
4. The value of objects is the actual string o Wildcard expansion happens in the rule for foo so that each existing o file becomes a prerequisite of foo and will be recompiled if necessary But what if you delete all the o files When a wildcard matches no files it is left as it is so then foo will depend on the oddly named file o Since no such file is likely to exist make will give you an error saying it cannot figure out how to make This is not what you want Actually it is possible to obtain the desired result with wildcard expansion but you need more sophisticated techniques including the wildcard function and string substitution See Section 4 3 3 The function wildcard on page 30 Microsoft operating systems MS DOS and MS Windows use backslashes to separate directories in pathnames like so c foo bar baz c This is equivalent to the Unix style c foo bar baz c the c part is the so called drive letter When make runs on these systems it supports backslashes as well as the Unix style forward slashes in pathnames However this support does include the wildcard expansion where backslash is a quote character Therefore you must use Unix style slashes in these cases The function wildcard Wildcard expansion happens automatically in rules But wildcard expansion does not normally take place when a variable is set or inside the arguments of a function If you want to do wildca
5. 107 ol PE 107 just print 107 107 keep going eere 107 107 oad average 107 106 makefile eti reete 106 00 107 107 222 110 no builtin rules sss 108 no builtin variables 108 no keep going 109 109 I 107 soldsfile iu e eet ens 107 oVerrides ecce 106 3D ipei eae 108 print data base 108 print directory 60 109 OO cse eei reduce utes 108 108 181 185 Index quiet s eei 109 d EM 108 108 rM NM 107 AERE 109 Recte coon ERE DTE ETUR 109 Ee E 109 TERMS 109 109 e EH net 109 109 2 109 Wi 110 60 109 warn undefined variables 110 Whati a tical Eee aie erated 110 Overriding makef
6. dir dirs files 5 dir dirs find_files 4 ST9 gmake Reference Manual 8 Functions to Transform Text 8 5 Note 3 Here we use the variable files this way We use plain to define recursively expanding variable so that its value contains an actual function call to be re expanded under the control of foreach simply expanded variable would not do since wildcard would be called only once at the time of defining find files The foreach function has no permanent effect on the variable VAR its value and flavor after the foreach function call are the same as they were beforehand other values which are taken from LIST are in effect only temporarily during the execution of foreach The variable VAR is a simply expanded variable during the execution of foreach If VAR was undefined before the foreach function call it is undefined after the call See Section 6 2 The two flavors of variables on page 64 You must take care when using complex variable expressions that result in variable names because many strange things are valid variable names but are probably not what you intended For example files 5 Esta escrito espanol b c ch find files might be useful if the value of ind files references the variable whose name is Esta escrito en espanol es un nombre bastante largo no but it is more likely to be a mistake
7. will echo Huh foo expands bar which expands 5 ugh which finally expands to Huh This flavor of variable is the only sort supported by other versions of make It has its advantages and its disadvantages An advantage most would say is that CFLAGS include dirs O include dirs Ifoo Ibar 4 ST9 gmake Reference Manual 6 How to Use Variables 3 will do what was intended when CFLAGS is expanded a command it will expand to Ifoo Ibar O A major disadvantage is that you cannot append something on the end of a variable as in CFLAGS CFLAGS O because it will cause an infinite loop in the variable expansion Actually make detects the infinite loop and reports an error Another disadvantage is that any functions see Section 8 Functions to Transform Text on page 85 referenced in the definition will be executed every time the variable is expanded This makes make run slower worse it causes the wildcard and shell functions to give unpredictable results because you cannot easily control when they are called or even how many times To avoid all the problems and inconveniences of recursively expanded variables there is another flavor simply expanded variables Simply expanded variables are defined by lines using see Section 6 5 Setting variables on page 70 The value of a simply expanded variable is scanned once and for all expanding any references to other variable
8. eet rh enge 118 meet 118 118 GXXEDAQGS aeter fete THER 119 D datadit ia et de nus 148 dir tht E mega tuat 89 Directives summary 161 Meri pe 32 directory xoi ir etie 139 Directory search for link libraries 35 Directory searches PSHOMMING Eee tent 33 Double colon 45 E Empty 62 Empty target 222 39 ClO ML M RC 97 Errors generated by 167 Events recording a 39 OXOC Prefix ess 147 179 185 Index F do 118 8 ida een teet 119 ee ee edic 88 fiter 88 findstring iicet eed D cene 87 firStWOr G 91 Flags testing 82 TONG AGH re E a 92 Fortran programs COMPING seek cete 113 preprocessing 114 Function call Syntax Of asistentes d 85 Function wildcard 30 went 85 addprefix itte 90 addsulfix n ti RN 90 b sename siete 90 Calls e fette ade 94 controlling 97 dil eut 89 Info iE E EE 97
9. names 28 Searching directories for prerequisites 122 31 Phony targets Pg 36 Rules without commands or prerequisites 38 Empty target files to record events 42 2 24 2 39 Special built in target names 39 Multiple targets in a file eta 41 3 185 410 4 11 4 12 4 13 Chapter 5 5 1 5 2 5 3 5 4 5 5 5 6 5 7 5 8 Chapter 6 6 1 6 2 6 3 6 4 6 5 6 6 6 7 6 8 6 9 6 10 6 11 Chapter 7 7 1 7 2 7 3 Chapter 8 8 1 8 2 8 3 4 185 Table of Contents Multiple rules for one target 42 Static Pattern rules ce eco ter eren eene 43 DOUDIG GOlOM usan Pc 45 Generating prerequisites automatically 46 Writing Commands in Rules 49 Cotimarid eerTolllt do hase ao Pec de pe cie p iv red vl 49 Gommand execut 50 Donar fedes luf casita 51 Errors incommandS eese 53 Interrupting or killing make aoo ette e e edite ce bus 54 Recursive use of make 5 tao pio lacte 55 Defining canned command se
10. MAKEINFO RANLIB TEXI2DVI When you use ranlib ldconfig you should make sure nothing bad happens if the system does not have the program in question Arrange to ignore an error ky ST9 gmake Reference Manual 14 Makefile Conventions 14 3 4 from that command and print a message before the command to tell the user that failure of this command does not mean a problem The Autoconf AC PROG RANLIB macro can help with this If you use symbolic links you should implement a fallback for systems that don t have symbolic links Additional utilities that can be used via Make variables are chgrp chmod chown mknod It is ok to use other utilities in Makefile portions or scripts intended only for particular systems where you know those utilities exist Variables for specifying commands Makefiles should provide variables for overriding certain commands options and 50 on In particular you should run most utility programs via variables Thus if you use Bison have a variable named BISON whose default value is set with BISON bison and refer to it with BISON whenever you need to use Bison File management utilities such as rm mv and so on need not be referred to through variables in this way since users don t need to replace them with other programs Each program name variable should come with an options variable that is used to
11. There are a few of problems with this method however First any error detected in a submake is not noted by this rule so it will continue to build the rest of the directories even when one fails This can be overcome by adding shell commands to note the error and exit but then it will do so even if make is invoked with the option which is unfortunate Second and perhaps more importantly you cannot take advantage of the parallel build capabilities of make using this method since there is only one rule By declaring the subdirectories as phony targets you must do this as the subdirectory obviously always exists otherwise it won t be built you can remove these problems SUBDIRS foo bar baz PHONY subdirs SUBDIRS subdirs S SUBDIRS SUBDIRS 5 5 foo baz Here we ve also declared that the oo subdirectory cannot be built until after the baz subdirectory is complete this kind of relationship declaration is particularly important when attempting parallel builds A phony target should not be a prerequisite of a real target file if it is its commands are run every time make goes to update that file As long as a phony target is never a prerequisite of a real target the phony target commands will be executed only 37 185 4 Writing Rules ST9 gmake Reference Manual 4 6 38 185 when the phony target is a specified goal see Section 9 2 Arguments to specify the goals on page 99 Phony
12. 149 om ettet 56 Shell 5 97 Shell commands WHITING 2 etit td Ete 34 gere PM E 88 Standard targets 153 Static pattern 43 uice 43 versus implicit rules 45 SUP Tm 87 Sub make communicating options 0 58 de Perrin 56 SUDSLU 86 Substitution 67 90 Su ffix r les ate 129 for archive files 135 support contact numbers 177 for development 177 Syntax Of a TUlez sen c 27 SySConfdir 149 M PEE 137 ANGLE 3 eee ctas hat ai 118 Target names DEEAULT iiri 40 DELETE ON 40 EXPORT ALL VARIABLES 41 E 41 40 PEIONY 39 inn aa 40 SECONDARY acci foe nas cep 40 doc UM QUI an Yay 41 iSUEEIXES ra eta
13. For example given objects mainl o foo o main2 o bar o mains mainl o main2 o the following generates a list which contains all the object files not in mains S filter out mains objects sort LIST Sorts the words of LIST in lexical order removing duplicate words The output is a list of words separated by single spaces Thus S sort foo bar lose returns the value bar foo lose Incidentally since sort removes duplicate words you can use it for this purpose even if you don t care about the sort order Here is a realistic example of the use of subst and patsubst Suppose that a makefile uses the VPATH variable to specify a list of directories that make should search for prerequisite files see Section 4 4 1 VPATH search path for all SZA ST9 gmake Reference Manual 8 Functions to Transform Text 8 3 3 prerequisites on page 31 This example shows how to tell the compiler to search for header files in the same list of directories The value of vPATH is a list of directories separated by colons such as src headers First the subst function is used to change the colons to spaces subst VPATH This produces src headers Then patsubst is used to turn each directory name into a I flag These can be added to the value of the variable CFLAGS which is passed automatically to the C compiler like this override CFLAGS S patsubst I subst 5 The e
14. Normally you should call your makefile either makefile or Makefile We recommend Makefile because it appears prominently near the beginning of a directory listing right near other important files such as README The first name checked GNUmakefile is not recommended for most makefiles You should use this name if you have a makefile that is specific to GNU make and will not be understood by other versions of make Other make programs look for makefile and Makefile but not GNUmakefile If make finds none of these names it does not use any makefile Then you must specify a goal with a command argument and make will attempt to figure out how to remake it using only its built in implicit rules See Section 10 1 Using implicit rules on page 111 for more information If you want to use a nonstandard name for your makefile you can specify the makefile name with the f or file option The arguments f or file NAME tell make to read the file NAME as the makefile If you use more than one f or file option you can specify several makefiles All the makefiles are effectively concatenated in the order specified The default makefile names GNUmakefile makefile and Makefile are not checked automatically if you specify f or file Including other makefiles The include directive tells make to suspend reading the current makefile and read one or more other makefiles before continuing The directive is a
15. The if function The if function provides support for conditional expansion in a functional context as opposed to the GNU make makefile conditionals such as ifeq see Section 7 2 Syntax of conditionals on page 80 An if function call can contain either two or three arguments if CONDITION THEN PART ELSE PART The first argument CONDITION first has all preceding and trailing whitespace stripped then is expanded If it expands to any non empty string then the condition is considered to be true If it expands to an empty string the condition is considered to be false If the condition is true then the second argument THEN PART is evaluated and this is used as the result of the evaluation of the entire function If the condition is false then the third argument ELSE PART is evaluated and this is the result of the if function If there is no third argument the if function evaluates to nothing the empty string Only one of the THEN PART or the ELSE PART Will be evaluated never both Thus either can contain side effects such as she11 function calls etc 93 185 8 Functions to Transform Text ST9 gmake Reference Manual 8 6 94 185 The cali function The call function is unique in that it can be used to create new parameterized functions You can write a complex expression as the value of a variable then use call to expand it with different values The syntax of the
16. UPDATING ARCHIVE FILES Archive files are files containing named subfiles called members they are maintained with the program ar and their main use is as subroutine libraries for linking Archive members as targets An individual member of an archive file can be used as a target or prerequisite in make You specify the member named MEMBER in archive file ARCHIVE as follows ARCHIVE MEMBER This construct is available only in targets and prerequisites not in commands Most programs that you might use in commands do not support this syntax and cannot act directly on archive members Only ax and other programs specifically designed to operate on archives can do so Therefore valid commands to update an archive member target probably must use ar For example this rule says to create a member hack o in archive foolib by copying the file hack o foolib hack o hack o ar cr foolib hack o In fact nearly all archive member targets are updated in just this way and there is an implicit rule to do it for you The c flag to ar is required if the archive file does not already exist To specify several members in the same archive you can write all the member names together between the parentheses For example foolib hack o kludge o is equivalent to foolib hack o foolib kludge o You can also use shell style wildcards in an archive member reference See Section 4 3 Using wildcard characters in file name
17. Use the v or version option to print version and copyright information Use the h or help option to summarize the options to make Simply expanded variables See Section 6 2 The two flavors of variables on page 64 Pass command line variable assignments automatically through the variable MAKE to recursive make invocations See Section 5 6 Hecursive use of make on page 55 Use the C or directory command option to change directory See Section 9 7 Summary of options on page 106 for more information Make verbatim variable definitions with define See Section 6 8 Defining variables verbatim on page 74 Declare phony targets with the special target PHONY Andrew Hume of AT amp T Bell Labs implemented a similar feature with a different syntax in his mk program This seems to be a case of parallel discovery See Section 4 5 Phony targets on page 36 for more information Manipulate text by calling functions See Section 8 Functions to Transform Text on page 85 Use the o or oid file option to pretend a file s modification time is old See Section 9 4 Avoiding recompilation of some files on page 103 Conditional execution This feature has been implemented numerous times in various versions of make it seems a natural extension derived from the features of the C preprocessor and similar macro languages and is not a revolutionary concept See Chapter 7 Conditional Parts of Makefiles on page 79 Specify a
18. objects cc o edit objects objects defs h kbd o command o files o command h 4 ST9 gmake Reference Manual 2 Introduction to Makefiles 2 7 3 display o insert o search o files o buffer h Here defs h is given as a prerequisite of all the object files command h and buffer h are prerequisites of the specific object files listed for them Whether this is better is a matter of taste it is more compact but some people dislike it because they find it clearer to put all the information about each target in one place Rules for cleaning the directory Compiling a program is not the only thing you might want to write rules for Makefiles commonly tell how to do a few other things besides compiling a program for example how to delete all the object files and executables so that the directory is clean Here is how we could write a make rule for cleaning our example editor clean rm edit objects In practice we might want to write the rule in a somewhat more complicated manner to handle unanticipated situations We would do this PHONY clean clean rm edit objects This prevents make from getting confused by an actual file called clean and causes it to continue in spite of errors from rm See Section 4 5 Phony targets on page 36 and Section 5 4 Errors in commands on page 53 for more information A rule such as this should not be placed at the beginning of the makefile because we do not want it to
19. 121 Defining last resort default rules 22 128 Old fashioned suffix rules ote deut 129 Implicit rule search algorm 130 Updating Archive Files 133 Archive members as targets 133 Implicit rule for archive member targets 40222222 133 Dangers WHEN USING arehilVes etg deco eee 135 Suffix rules for archive files aede coe PE nett Rene pre Erie 135 Features of GNU Make 137 Incompatibilities amp Missing Features 141 Makefile Conventions 143 General conventions for makefiles 143 5 185 Table of Contents 14 2 Utilities n makefiles e ER PER 144 14 3 Variables for specifying commands 145 14 4 Variables for installation directories 044444 1 147 14 5 Standard targets for Users eo dace er edel ier Ode dh teed 153 14 6 Install command categories speso ceo ee PU 157 Appendix A Quick Reference 161 Appendix B Errors Generated by 167 Appendix C Complex Makefile Example 171 Product SUuDDOFT XR SS E EE ERE ELE 177
20. 40 alli ey conecta 101 IDOL E 39 Checo ete 101 Clean 101 6016 0221 101 101 e Ee ett 101 Trim 101 mostlyclean cesses 101 ero e 101 realcl an sacer Dareus 101 Ee E E 101 TAGS tet S aaa 101 IAE socie i ect E T 101 101 Targets standard itti 153 TEX LK 118 a tu de dre n 116 Detracto ce 118 s Som ee Mofa i fett 116 U Using implicit 2 22 22 111 V AMEN CRM M REN EUM EE 139 Variable assignment 25 Variable names computed eee repos 67 Variable 63 MariableS tacet vein ead epos a aka 14 appending text 71 BRA LATUR 117 ARELAGS x dte e A 118 BAS 117 ASFA GS 119 Didi icis cicer 147 5 PEU 117 119 oC 118 GOFLAGS oerte needed UE eden 119 CPP uL RE 118 CPPFR AGS isa x n testet 119 CTANGLE 118 118 118 CXXELAGS 11
21. Specifies a directory DIR to search for included makefiles See Section 3 3 Including other makefiles page 20 If several I options are used to specify several directories the directo ries are searched in the order specified Specifies the number of jobs commands to run simultaneously With no argument make runs as many jobs simultaneously as possible If there is more than one j option the last one is effective See Section 5 3 Parallel exe cution on page 51 for more information on how commands are run This option is ignored on MS DOS Continue as much as possible after an error While the target that failed and those that depend on it cannot be remade the other pre requisites of these targets can be processed all the same See Section 9 6 Testing the compi lation of a program on page 105 Specifies that no new jobs commands should be started if there are other jobs running and the load average is at least LOAD a floating point number With no argument removes a previous load limit See Section 9 3 Instead of executing the commands on page 102 Print the commands that would be executed but do not execute them See Section 9 3 Instead of executing the commands on page 102 Do not remake the file FILE even if it is older than its prerequisites and do not remake any thing on account of changes in FILE Essen tially the file is treated as very old and its rules are ignored See Section 9 4
22. 1 1 function is 5 11 VARIABLE PARAM PARAM When make expands this function it assigns each PARAM to temporary variables 1 2 etc The variable 5 0 will contain VARIABLE There is no maximum number of parameter arguments There is no minimum either but it doesn t make sense to use 11 with no parameters Then VARIABLE is expanded as a make variable in the context of these temporary assignments Thus any reference to 1 in the value of VARIABLE will resolve to the first PARAM in the invocation of ca11 Note that VARIABLE is the name of variable not a reference to that variable Therefore you would not normally use a or parentheses when writing it You can however use a variable reference in the name if you want the name not to be a constant If VARIABLE is the name of a built in function the built in function is always invoked even if a make variable by that name also exists Some examples may make this clearer This macro simply reverses its arguments reverse 2 1 foo ab bar call reverse bar will contain a This one is slightly more interesting it defines a macro to search for the first instance of a program in PATH pathsearch firstword wildcard addsufix 1 subst PATH LS 5 11 pathsearch ls Now the variable Ls contains bin 1s or si
23. 9 3 9 4 9 5 9 6 9 7 10 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 8 11 114 11 2 11 3 11 4 12 13 14 141 r Table of Contents The foreach Tlunclloni et ein Me 92 UE Aci c 93 The ea ET Tn BOTE e EODD Er 94 The origin il es Cui i RR tsi eR Id dole Gare 95 MiG Sed 52 Did o QUO wei ee amet ende 97 Functions that control mak tnnt nnn tn entente eed 97 How to Run Make 99 Arguments to specify the makefile 99 Arguments to specify the 99 Instead of executing the commands 102 Avoiding recompilation of some files 2 103 Ovetriding variables thi i btt ont od ap tak 104 Testing the compilation of a program 105 Summary of ODIO Sra aereas emt dui mtt 106 ImpliciERules o Shee Sea ET DE AREE ES 111 Using implicit rules e 111 Catalog or implicit rules ee edente err nad eh ae SO eR NES 113 Variables used by implicit rules 117 Chains of implicit rules tee oec i eter HEN ER 119 Defining and redefining pattern rules
24. Fh Fh Fh Fh H B HHHH Fh Fh DRENAME MISSING DFTRUNCATE MISSING I system call you lack rename system call you lack ftruncate DV7 On Version 7 Unix not tested in a long time DEMUL OPEN3 If you lack a 3 argument version dE dE dE dE db dE de dE dE db dE dE dE dE dE db dE dE dE dE db dE d of open and want to emulate it 4 172 185 ST9 gmake Reference Manual Appendix C Complex Makefile Example DNO O DXENI dE dE db dE dE od Set th in whi RTAPELIB LIBS with system calls you do have PEN3 If you lack the 3 argument open and want to disable the tar k option instead of emulating open X If you have sys inode h and need it 94 to be included I DSIGTYPE int DDIRENT DSTRSTR MISSING DVPRINTF MISSING DBSD42 is to rtapelib o unless you defined NO REMOTE ch case make it empty rtapelib o DEF AR ILE dev rmt8 DEFBLOCKING 20 CDEBUG CFI E D Q ll LDFLAGS prefix Prefix normal binprefi The di bindir The di infodir SRCI SRC2 SRC3 SRCS OBJ1 OBJ2 OBJ3 OBJS AUX 4 g CDEBUG I I srcdir DEFS DDEF AR FILE V DEF AR FILE N DDEFBLOCKING DEFBLOCKING g usr local for each installed progr
25. Functions to Transform Text ST9 gmake Reference Manual 90 185 whitespace separated file names as the argument had but we do not see any other valid alternative For example notdir src foo c hacks produces the result foo c hacks suffix NAMES Extracts the suffix of each file name in NAMES If the file name contains a period the suffix is everything starting with the last period Otherwise the suffix is the empty string This frequently means that the result will be empty when NAMES is not and if NAMES contains multiple file names the result may contain fewer file names For example suffix src foo c src 1 0 bar c hacks produces the result c basename NAMES Extracts all but the suffix of each file name in NAMES If the file name contains a period the basename is everything starting up to and not including the last period Periods in the directory part are ignored If there is no period the basename is the entire file name For example basename src foo c src 1 0 bar hacks produces the result src foo src 1 0 bar hacks addsuffix SUFFIX NAMES The argument NAMES is regarded as a series of names separated by whitespace SUFFIX is used as a unit The value of SUFFIX is appended to the end of each individual name and the resulting larger names are concatenated with single spaces between them For example addsuffix c foo bar produces the result foo c
26. Lex for C 115 Lex for Ratfor 115 PRAGS ent 119 149 libeXeGdi i dee ette 148 Limitations 8 Link 35 LINKING 114 Lint 115 t mE 150 lOCalStateir 2 149 Index M um 137 Make features 4 4 0 0 1 4 137 incompatibilities esse 141 interrupting 54 iid pet 54 missing 141 recursive use 55 win32 8 MAKE 55 MAKE VERSION eee 140 MAKECMDGOALS 100 Makefiles conditional syntax 26 contents 19 22 143 example dece eter 171 Incl ditrig iR REPRE 20 NAMING ERE EE 20 OVENIGING oet eri ttd 24 processing 13 readirig ee 25 remaking 22 rule 2 26 specifying name 99
27. Print a message containing the working direc tory both before and after executing the make file This may be useful for tracking down errors from complicated nests of recursive make commands See Section 5 6 Hecursive use of make on page 55 In practice you rarely need to specify this option since make does it for Disable printing of the working directory under This option is useful when w is turned on automatically but you do not want to see the extra messages 109 185 9 How to Run Make 110 185 W FILE what if FILE new file FILE assume new FILE warn undefined variables ST9 gmake Reference Manual Pretend that the target FILE has just been modified When used with the flag this shows you what would happen if you were to modify that file Without n it is almost the same as running a touch command on the given file before running make except that the modification time is changed only in the imagi nation of make See Section 9 3 Instead of executing the commands on page 102 Issue a warning message whenever make sees a reference to an undefined variable This can be helpful when you are trying to debug makefiles which use variables in com plex ways 4 ST9 gmake Reference Manual 10 Implicit Rules 10 10 1 4 IMPLICIT RULES Certain standard ways of remaking target files are used very often For example one customary way to make an object fi
28. c de tc ets 88 mE 88 StEltig t des 87 EC 91 for analysis dicte te am Et 86 for string substitution sss 86 TOC ACH oie see be 92 93 jo 91 MOU 89 ONIQIN 2 venti etie 95 patsu bst 5 oc het e 86 Shell cod eren Re teen eres 97 Cle 88 eel mee de es 87 SUDSt ie Pet Ee etg 86 90 summary 161 98 92 tede eatis 91 91 91 180 185 G GET pn Eee 118 GEEAGS Lee eo etus 119 Galge Ganaa RI Eae 99 H dm 139 o etie e eda ted ees 139 93 Implicit rules and directory 35 cancelling cese 128 Catalog 113 for archive member targets 133 last teSOrt etti e rites 128 search algorithm 130 versus static pattern rules 45 includedii bee 150 rio A 116 UNTO 149 Install command categories 157 J A 91 L UDEDAQSS nm ate E ae 119 mE 118
29. foo that includes another makefile bar You want a variable bletch to be defined in bar if you run the command make bar even if the environment contains a definition of bletch However if foo defined bletch before including bar you do not want to override that definition This could be done by using an override directive in oo giving that definition precedence over the later definition in bar unfortunately the override directive would also override any command line definitions So bar could include ifdef bletch ifeq S origin bletch environment bletch barf gag etc endif endif If bletch has been defined from the environment this will redefine it If you want to override a previous definition of bletch if it came from the environment even under e you could instead write ifneq S findstring environment origin bletch bletch barf gag etc endif Here the redefinition takes place if origin bletch returns either environment environment override See Section 8 2 Functions for string substitution and analysis on page 86 4 ST9 gmake Reference Manual 8 Functions to Transform Text 8 8 8 9 3 she11 function The shell function is unlike any other function except the wildcard function see Section 4 3 3 The function wildcard on page 30 in that it communicates with the world outside of make The shell function performs the same function that backquotes perform
30. gmake Reference Manual 5 2 Note 50 185 Command execution When it is time to execute commands to update a target they are executed by making a new subshell for each line In practice make may take shortcuts that do not affect the results This implies that shell commands such as that set variables local to each process will not affect the following command lines On MS DOS the value of current working directory is global so changing it will affect the following command lines on those systems If you want to use to affect the next command put the two on a single line with a semicolon between them Then make will consider them a single command and pass them together to a shell which will execute them in sequence For example foo bar lose cd bar gobble lose gt foo If you would like to split a single shell command into multiple lines of text you must use a backslash at the end of all but the last subline Such a sequence of lines is combined into a single line by deleting the backslash newline sequences before passing it to the shell Thus the following is equivalent to the preceding example foo bar lose bar gobble lose foo The program used as the shell is taken from the variable SHELL By default the program bin sh is used On MS DOS if SHELL is not set the value of the variable COMSPEC which is always set is used instead The processing of lines that set the variab
31. if your Foo package provides a header file oo n then it should install the header file in the o1dincludedir directory if either 1 there is no foo h there or 2 the foo h that exists came from the Foo package To tell whether oo h came from the Foo package put a magic string in the file part of a comment and grep for that string Unix style man pages are installed in one of the following mandir manidir man2dir manext manlext The top level directory for installing the man pages if any for this package It will normally be usr local man but you should write it as prefix man If you are using Auto conf write it as mandir The directory for installing section 1 man pages Write it as mandir manl The directory for installing section 2 man pages Write it as 5 mandir man2 Don t make the primary documentation for any GNU software be aman page Write a manual in Texinfo instead Man pages are just for the sake of people running GNU software on Unix which is a secondary application only The file name extension for the installed man page This should contain a period followed by the appropriate digit it should normally be 1 The file name extension for installed section 1 man pages 151 185 14 Makefile Conventions ST9 gmake Reference Manual man2ext The file name extension for installed section 2 man pages Use these names instead of manext if the package needs to insta
32. keep going flag This tells make to continue to consider the other prerequisites of the pending targets remaking them if necessary before it gives up and returns nonzero status For example after an error in compiling one object file make k will continue compiling other object files even though it already knows that linking them will be impossible In addition to continuing after failed shell commands make k will continue as much as possible after discovering that it does not know how to make a target or prerequisite file This will always cause an error message but without k it is a fatal error see Section 9 7 Summary of options on page 106 for more information The usual behavior of make assumes that your purpose is to get the goals up to date once make learns that this is impossible it might as well report the failure immediately The k flag says that the real purpose is to test as much as possible of the changes made in the program perhaps to find several independent problems so that you can correct them all before the next attempt to compile This is why Emacs M x compile command passes the k flag by default 105 185 9 How to Run Make 9 7 106 185 Summary of options ST9 gmake Reference Manual Here is a list of all the options make understands b m DIR directory DIR debug environment overrides FILE file FILE makefile FILE h help i ignore error
33. the directory where make finds it This is done with the automatic variables such as see Section 10 5 3 Automatic variables on page 123 For instance the value of is a list of all the prerequisites of the rule including the names of the directories in which they were found and the value of 56 is the target Thus 60 10 amp cc c S CFLAGS o 4 5 9 gmake Reference Manual 4 Writing Rules 4 4 5 4 4 6 3 The variable CFLAGS exists so you can specify flags for C compilation by implicit rules we use it here for consistency so it will affect all C compilations uniformly see Section 10 3 Variables used by implicit rules on page 117 for more information Often the prerequisites include header files as well which you do not want to mention in the commands The automatic variable is just the first prerequisite VPATH src headers foo o foo c defs h hack h cc c S CFLAGS lt o G Directory search and implicit rules The search through the directories specified in vPATH or with vpath also happens during consideration of implicit rules See Section 10 1 Using implicit rules on page 111 for more information For example when file oo o has no explicit rule make considers implicit rules such as the built in rule to compile foo c if that file exists If such a file is lacking in the current directory the appropriate directories are searched for it If foo c exists
34. 157 185 14 Makefile Conventions ST9 gmake Reference Manual 158 185 directory which does not come entirely and solely from the package being installed It is a post installation command because it needs to be done after the normal command which installs the package s Info files Most programs don t need any pre installation commands but we have the feature just in case it is needed To classify the commands in the install rule into these three categories insert category lines among them category line specifies the category for the commands that follow A category line consists of a tab and a reference to a special Make variable plus an optional comment at the end There are three variables you can use one for each category the variable name specifies the category Category lines are no ops in ordinary execution because these three Make variables are normally undefined and you should not define them in the makefile Here are the three possible category lines each with a comment that explains what it means PRE INSTALL Pre install commands follow 5 5 INSTALL Post install commands follow NORMAL INSTALL Normal commands follow If you don t use a category line at the beginning of the install rule all the commands are classified as normal until the first category line If you don t use any category lines all the commands are classified as normal These are the category lin
35. 185 2 Introduction to Makefiles ST9 gmake Reference Manual 2 6 16 185 When a c file is used automatically in this way it is also automatically added to the list of prerequisites We can therefore omit the c files from the prerequisites provided we omit the commands Here is the entire example with both of these changes and a variable objects as suggested above objects main o kbd o command o display o insert o search o files o utils o edit objects cc o edit 5 objects main o defs h kbd o defs h command h command o defs h command h display o defs h buffer h insert o defs h buffer h search o defs h buffer h files o defs h buffer h command h utils o defs h PHONY clean clean rm edit objects This is how we would write the makefile in actual practice The complications associated with clean are described elsewhere See Section 4 5 Phony targets on page 36 and Section 5 4 Errors in commands on 53 for more information Because implicit rules are so convenient they are important You will see them used frequently Another style of makefile When the objects of a makefile are created only by implicit rules an alternative style of makefile is possible In this style of makefile you group entries by their prerequisites instead of by their targets Here is what one looks like objects main o kbd o command o display o insert o search o files o utils o edit
36. 4 2 Rule syntax on page 27 for more information 167 185 Appendix B Errors Generated by Make ST9 gmake Reference Manual B 3 B 4 B 5 B 6 B 7 168 185 commands commence before first target Stop missing rule before commands Stop This means the first thing in the makefile seems to be part of a command script it begins with a TAB character and doesn t appear to be a legal make command such as a variable assignment Command scripts must always be associated with a target The second form is generated if the line has a semicolon as the first non whitespace character make interprets this to mean you left out the target prerequisite section of a rule See Section 4 2 Rule syntax on page 27 No rule to make target XXX No rule to make target needed by This means that make decided it needed to build a target but then couldn t find any instructions in the makefile on how to do that either explicit or implicit including in the default rules database If you want that file to be built you will need to add a rule to your makefile describing how that target can be built Other possible sources of this problem are typos in the makefile if that filename is wrong or a corrupted source tree if that file is not supposed to be built but rather only a prerequisite No targets specified and no makefile found Stop No targets Stop The former means that you didn t provide any tar
37. 5 3 Parallel execution on page 51 If you set it to some numeric value N and your operating system supports it most any UNIX system will others typically won t the parent make and all the sub makes will communicate to ensure that there are only N jobs running at the same time between them all Any job that is marked recursive see Section 9 3 Instead of executing the commands on page 102 doesn t count against the total jobs otherwise we could get N sub makes running and have no slots left over for any real work If your operating system doesn t support the above communication then j 1 is always put into MAKEFLAGS instead of the value you specified This is because if the 3 option were passed down to sub makes you would get many more jobs running in parallel than you asked for If you give j with no numeric argument meaning to run as many jobs as possible in parallel this is passed down since multiple infinities are no more than one If you do not want to pass the other flags down you must change the value of MAKEFLAGS like this subsystem cd subdir amp amp 5 MAKEFLAGS The command line variable definitions really appear in the variable MAKEOVERRIDES and MAKEFLAGS contains a reference to this variable If you do want to pass flags down normally but don t want to pass down the command line variable definitions you can reset MAKEOVERRIDES to empty like this MAKEOVERRIDES
38. 7 4 8 4 the target FORCE satisfies the special conditions so the target 1 that depends on it is forced to run its commands There is nothing special about the name FORCE but that is one name commonly used this way As you can see using FORCE this way has the same results as using PHONY clean Using PHONY is more explicit and more efficient However other versions of make do not support PHONY thus FORCE appears in many makefiles See Section 4 5 Phony targets on page 36 for more information Empty target files to record events The empty target is a variant of the phony target it is used to hold commands for an action that you request explicitly from time to time Unlike a phony target this target file can really exist but the file s contents do not matter and usually are empty The purpose of the empty target file is to record with its last modification time when the rule s commands were last executed It does so because one of the commands is a touch command to update the target file The empty target file should have some prerequisites otherwise it doesn t make sense When you ask to remake the empty target the commands are executed if any prerequisite is more recent than the target in other words if a prerequisite has changed since the last time you remade the target Here is an example print foo c bar c lpr p touch print With this rule make print will execute the 1eper c
39. 8 8 The shell function on page 97 origin VARIABLE Return a string describing how the make variable VARI ABLE Was defined See Section 8 7 The origin func tion on page 95 S foreach VAR WORDS TI Evaluate TEXT with VAR bound to each word in WORDS and concatenate the results See Section 8 4 The foreach function on page 92 call VAR PARAM Evaluate the variable VAR replacing any references to 1 2 with the first second etc PARAM values See Section 8 6 The call function on page 94 164 185 4 5 9 gmake Reference Manual Appendix A Quick Reference The following table summarizes the automatic variables that GNU make understands Automatic p Description variables P 82 name of the target LEN The target member name when the target is an archive member The name of the first prerequisite The names of all the prerequisites that are newer than the target with spaces between them For prerequisites which are archive members only the member named is used see Chapter 11 Updating Archive Files on page 133 5 5 The names of all the prerequisites with spaces between them For prerequisites which are archive members only the member named is used see Chapter 11 Updating Archive Files page 133 The value of omits duplicate prerequi sites while retains them and preserves their order The stem with which an implicit rule matches see Section 10 5
40. Avoiding recom pilation of some files on page 103 107 185 9 How to Run Make P print data base q r no builtin rules R no builtin variables 108 185 ST9 gmake Reference Manual Print the data base rules and variable values that results from reading the makefiles then execute as usual or as otherwise specified This also prints the version information given by the v switch see below To print the data base without trying to remake any files use make To print the data base of pre defined rules and variables use make p f dev null Question mode Do not run any commands or print anything just return an exit status that is zero if the specified targets are already up to date one if any remaking is required or two if an error is encountered See Section 9 3 Instead of executing the commands on page 102 Eliminate use of the built in implicit rules see Section 10 1 Using implicit rules on page 111 for more information You can still define your own by writing pattern rules see Section 10 5 Defining and redefining pattern rules on page 121 The r option also clears out the default list of suffixes for suffix rules see Sec tion 10 7 Old fashioned suffix rules on page 129 But you can still define your own suffixes with a rule for SUFFIXES and then define your own suffix rules Note that only rules are affected by the r option
41. MAKEFILES to cause all sub make commands to use additional makefiles The value of MAKEFILES is a whitespace separated list of file names This variable if defined in the outer level makefile is passed down through the environment then it serves as a list of extra makefiles for the sub make to read before the usual or specified ones See Section 3 4 The variable MAKEFILES on page 22 Communicating options to a sub make Flags such as s and k are passed automatically to the sub make through the variable MAKEFLAGS This variable is set up automatically by make to contain the flag letters that make received Thus if you do make ks then MAKEFLAGS gets the value ks As a consequence every sub make gets a value for MAKEFLAGS in its environment In response it takes the flags from that value and processes them as if they had been given as arguments See Section 9 7 Summary of options on page 106 for more information Likewise variables defined on the command line are passed to the sub make through MAKEFLAGS Words in the value of MAKEFLAGS that contain make treats as variable definitions just as if they appeared on the command line See Section 9 5 Overriding variables on page 104 r 5 9 gmake Reference Manual 5 Writing Commands in Rules Note 3 The options and w are not put into MAKEFLAGS these options are not passed down The j option is a special case see Section
42. Section 9 7 Summary of options on page 106 for more information The usual behavior assumes that your purpose is to get the specified targets up to date once make learns that this is impossible it might as well report the failure immediately The option says that the real purpose is to test as many of the changes made in the program as possible perhaps to find several independent problems so that you can correct them all before the next attempt to compile This is why Emacs compile command passes the k flag by default Usually when a command fails if it has changed the target file at all the file is corrupted and cannot be used or at least it is not completely updated Yet the file s timestamp says that it is now up to date so the next time make runs it will not try to update that file The situation is just the same as when the command is killed by a signal see below So generally the right thing to do is to delete the target file if the command fails after beginning to change the file make will do this if DELETE ON ERROR appears as a target This is almost always what you want make to do but it is not historical practice so for compatibility you must explicitly request it Interrupting or killing make If make gets a fatal signal while a command is executing it may delete the target file that the command was supposed to update This is done if the target file s last modification time has changed since m
43. Windows semi colons are used as separators of directory names in VPATH since the colon can be used in the pathname itself after the drive letter For example VPATH src headers specifies a path containing two directories src and headers which make searches in that order With this value of VPATH the following rule foo o foo c is interpreted as if it were written like this foo o src foo c assuming the file oo c does not exist in the current directory but is found in the directory src The vpath directive Similar to the vPATH variable but more selective is the vpatn directive note lower case which allows you to specify a search path for a particular class of file names those that match a particular pattern Thus you can supply certain search directories for one class of file names and other directories or none for other file names There are three forms of the vpath directive vpath PATTERN DIRECTORIES Specify the search path DIRECTORIES for file names that match PATTERN The search path DIRECTORIES is a list of directories to be searched separated by colons semi colons on MS DOS and MS Windows or blanks just like the search path used in the vPATH variable vpath PATTERN Clear out the search path associated with PATTERN vpath Clear all search paths previously specified with vpath directives A vpath pattern is a string containing a character The
44. a command script or on the right side of a recursive variable assignment it won t be evaluated until later The TEXT will be expanded before the error is generated For example ifdef ERROR1 S error error is 1 endif will generate a fatal error during the read of the makefile if the make variable ERRORI is defined Or 97 185 8 Functions to Transform Text ST9 gmake Reference Manual 98 185 ERR error found an error PHONY err err ERR will generate a fatal error while make is running if the err target is invoked warning TEXT This function works similarly to the error function above except that make doesn t exit Instead TEXT is expanded and the resulting message is displayed but processing of the makefile continues The result of the expansion of this function is the empty string 4 ST9 gmake Reference Manual 9 How to Run Make 9 1 9 2 4 HOW TO RUN MAKE A makefile that says how to recompile a program can be used in more than one way The simplest use is to recompile every file that is out of date Usually makefiles are written so that if you run make with no arguments it does just that But you might want to update only some of the files you might want to use a different compiler or different compiler options you might want just to find out which files are out of date without changing them By giving arguments when you run make you ca
45. again don t blame us To help make users aware of this the commands for the special maintainer clean target should start with these two echo This command is intended for maintainers to use it echo deletes files that may need special tools to rebuild Update a tags table for this program 155 185 14 Makefile Conventions ST9 gmake Reference Manual info Generate any Info files needed The best way to write the rules is as follows info foo info foo info foo texi chapl texi chap2 texi 5 MAKEINFO srcdir foo texi You must define the variable MAKEINFO in the Makefile It should run the makeinfo program which is part of the Texinfo distribution Normally a GNU distribution comes with Info files and that means the Info files are present in the source directory Therefore the Make rule for an info file should update it in the source directory When users build the package ordinarily Make will not update the Info files because they will already be up to date dvi Generate DVI files for all Texinfo documentation For example dvi foo dvi foo dvi foo texi chapl texi chap2 texi S TEXI2DVI S srcdir foo texi You must define the variable TEXI2DVI in the Makefile It should run the program texi2dvi which is part of the Texinfo distribution Alternatively write just the dependencies and allow GNU make to provide the command Note texi2dvi uses TeX to do the real wor
46. anything but we might well want to fix it Before reporting a bug make sure you ve actually found a real bug Carefully reread the documentation and see if it really says you can do what you re trying to do If it s not clear whether you should be able to do something or not report that too it s a bug in the documentation Before reporting a bug or trying to fix it yourself try to isolate it to the smallest possible makefile that reproduces the problem Then send us the makefile and the exact results make gave you Also say what you expected to occur this will help us decide whether the problem was really in the documentation Once you ve got a precise problem please send electronic mail to bug make gnu org Please include the version number of make you are using You can get this information with the command make version Be sure also to include the type of machine and operating system you are using If possible include the contents of the file config h that is generated by the configuration process Limitations of make for win32 Since make comes from the Unix world some differences especially with file paths must be considered if a standard shell is used command for MS DOS Windows 95 and Windows 98 and cmd exe for Windows NT If shells such as sh Or bash from the Unix world are used then there is no need to consider these differences Path separator The path separator used in make is However the D
47. are expanded by the shell For example here is a rule to delete all the object files clean rm o Wildcards are also useful in the prerequisites of a rule With the following rule in the makefile make print will print all the c files that have changed since the last time you printed them Ac lpr 5 touch print This rule uses print as an empty target file see Section 4 7 Empty target files to record events on page 39 The automatic variable is used to print only those files that have changed see Section 10 5 3 Automatic variables on page 123 Wildcard expansion does not happen when you define a variable Thus if you write this objects o then the value of the variable objects is the actual string o However if you use the value of objects in a target prerequisite or command wildcard expansion will take place at that time To set objects to the expansion instead use objects wildcard See Section 4 3 3 The function wildcard on page 30 for more information 29 185 4 Writing Rules ST9 gmake Reference Manual 4 3 2 4 3 3 Note 30 185 Pitfalls of using wildcards Now here is an example of a naive way of using wildcard expansion that does not do what you would intend Suppose you would like to say that the executable file foo is made from all the object files in the directory and you write this objects o foo 5 cc o foo 5 5 5
48. cc c display c insert o insert c defs h buffer h cc c insert c search o search c defs h buffer h cc search c files o files c defs h buffer h command h cc c files c utils o utils c defs h GG utrls c clean rm edit main o kbd o command o display o insert o search o files o utils o We split each long line into two lines using backslash newline this is like using one long line but is easier to read To use this makefile to create the executable file called edit type make 4 ST9 gmake Reference Manual 2 Introduction to Makefiles Note 2 3 3 To use this makefile to delete the executable file and all the object files from the directory type make clean In the example makefile the targets include the executable file eait and the object files main o and kbd o The prerequisites are files such as main c and defs h In fact each o file is both a target and a prerequisite Commands include c main c c kbd c When a target is a file it needs to be recompiled or relinked if any of its prerequisites change In addition any prerequisites that are themselves automatically generated should be updated first In this example edit depends on each of the eight object files the object file main o depends on the source file main c and on the header file ae s h A shell command follows each line that contains a target and prerequisites These shell commands say how to
49. compose a larger system For example suppose you have a subdirectory subdir which has its own makefile and you would like the containing directory s makefile to run make on the subdirectory You can do it by writing this subsystem cd subdir amp amp 5 or equivalently this see Section 9 7 Summary of options on page 106 for more information subsystem 5 C subdir You can write recursive make commands just by copying this example but there are many things to know about how they work and why and about how the sub make relates to the top level make For your convenience GNU make sets the variable CURDIR to the pathname of the current working directory for you If c is in effect it will contain the path of the new directory not the original The value has the same precedence it would have if it were set in the makefile by default an environment variable CURDIR will not override this value Setting this variable has no effect on the operation of make How the MAKE variable works Recursive make commands should always use the variable MAKE not the explicit command name make as shown here subsystem cd subdir amp amp 5 The value of this variable is the file name with which make was invoked If this file name was bin make then the command executed is subdir amp amp bin make If you use a special version of make to run the top level makef
50. default variables remain in effect see Section 10 3 Variables used by implicit rules on page 117 see the option below Eliminate use of the built in rule specific vari ables see Section 10 3 Variables used by implicit rules on page 117 You can still define your own of course The R option also auto matically enables the r option see above since it doesn t make sense to have implicit rules without any definitions for the variables that they use 4 3 ST9 gmake Reference Manual S silent quiet 5 no keep going touch version W print directory no print directory 9 How to Run Make Silent operation do not print the commands as they are executed See Section 5 1 Command echoing on page 49 Cancel the effect of the k option This is never necessary except in a recursive make where k might be inherited from the top level make via MAKEFLAGS see Section 5 6 Recursive use of make on page 55 or if you set k in MAKEFLAGS in your environment Touch files mark them up to date without really changing them instead of running their com mands This is used to pretend that the com mands were done in order to fool future invocations of make See Section 9 3 Instead of executing the commands on page 102 Print the version of the make program plus a copyright a list of authors and a notice that there is no warranty then exit
51. definition is a line that specifies a text string value for a variable that can be substituted into the text later The simple makefile example shows a variable definition for objects as a list of all object files see Section 2 4 Variables make makefiles simpler on page 14 A directive is a command for make to do something special while reading the makefile These include Reading another makefile see Section 3 3 Including other makefiles on page 20 Deciding based on the values of variables whether to use or ignore a part of the makefile see Chapter 7 Conditional Parts of Makefiles on page 79 Defining a variable from a verbatim string containing multiple lines see Section 6 8 Defining variables verbatim on page 74 in a line of a makefile starts a comment It and the rest of the line are ignored except that a trailing backslash not escaped by another backslash will continue the comment across multiple lines Comments may appear on any of the lines in the makefile except within a define directive and perhaps within commands where the shell decides what is a comment A line containing just a comment with perhaps spaces before it is effectively blank and is ignored 19 185 3 Writing Makefiles ST9 gmake Reference Manual 3 2 3 3 20 185 What name to give your makefile By default when make looks for the makefile it tries the following names in order GNUmakefile makefile and Makefile
52. described by the makefile often with a target called a11 See Section 9 2 Arguments to specify the goals on page 99 Rule example Here is an example of a rule foo o foo c defs h module for twiddling the frobs cc g foo c Its target is oo o and its prerequisites are foo c and defs h It has one command which is c g The command line starts with a tab to identify it as a command This rule says two things How to decide whether foo o is out of date it is out of date if it does not exist or if either or defs his more recent than it Howto update the file by running cc as stated The command does not explicitly mention de s h but we presume that oo c includes it and that that is why de s h was added to the prerequisites Rule syntax In general a rule looks like this TARGETS PREREQUISITES COMMAND 27 185 4 Writing Rules ST9 gmake Reference Manual 4 3 28 185 or like this TARGETS PREREQUISITES COMMAND COMMAND The TARGETS are file names separated by spaces Wildcard characters may be used see Section 4 3 Using wildcard characters in file names on page 28 anda name of the form A M represents member in archive file A see Section 11 1 Archive members as targets on page 133 Usually there is only one target per rule but occasionally there is a reason to have more see Section 4 9 Multiple targets in a rule
53. details on suffix rules Compiling C programs is made automatically from N c with a command of the form 5 CPPFLAGS CFLAGS Compiling C programs N o is made automatically from N cc or N C with a command of the form CXX c CPPFLAGS CXXFLAGS We encourage you to use the suffix cc for C source files instead of c Compiling Pascal programs is made automatically from with the command c PFLAGS Compiling Fortran and Ratfor programs is made automatically from N r N F or N f by running the Fortran compiler The precise command used is as follows c FFLAGS 5 c S FFLAGS S CPPFLAGS op 5 c S FFLAGS RFLAGS 113 185 10 Implicit Rules ST9 gmake Reference Manual 10 2 5 10 2 6 10 2 7 10 2 8 114 185 Preprocessing Fortran and Ratfor programs N f is made automatically from N x or N F This rule runs just the preprocessor to convert a Ratfor or preprocessable Fortran program into a strict Fortran program The precise command used is as follows 5 F S CPPFLAGS FFLAGS voy S FC S FFLAGS S RFLAGS Compiling Modula 2 programs N sym is made from N def with a command of the form M2C M2FLAGS DEFFLAGS N o is made from N mod the form is M2C M2FLAGS MODFLAGS Assembling and preprocessing assembler programs N o is made automaticall
54. for file names on page 89 addsuffix SUFFIX NAMES Append SUFFIX to each word in NAMES See Section 8 3 Functions for file names on page 89 4 163 185 Appendix A Quick Reference ST9 gmake Reference Manual addprefix PREFIX NAMES Prepend PREFIX to each word in NAMES See Section 8 3 Functions for file names on page 89 join LIST1 LIST2 Join two parallel lists of words See Section 8 3 Func tions for file names on page 89 Extract the Nth word one origin of TEXT See Section 8 3 Functions for file names on page 89 Count the number of words in TEXT See Section 8 3 Functions for file names on page 89 rdlist S E TE Returns the list of words in TEXT from s to E See Section 8 3 Functions for file names on page 89 firstword NAMES Extract the first word of NAMES See Section 8 3 Func tions for file names on page 89 wildcard PATTI Find file names matching a shell file name pattern not a pattern See Section 4 3 3 The function wildcard on page 30 When this function is evaluated make generates a fatal error with the message TEXT See Section 8 9 Func tions that control make on page 97 warning When this function is evaluated make generates a warn ing with the message TEXT See Section 8 9 Functions that control make on page 97 shell COMMAN Execute a shell command and return its output See Sec tion
55. gmake Reference Manual CC gcc O YACC bison y INSTALL usr local bin install c INSTALLDATA usr local bin install c m 644 Things you might add to DEFS DSTDC HEADERS If you have ANSI C headers and libraries DPOSIX If you have POSIX 1 headers and libraries DBSD42 If you have sys dir h unless you use DPOSIX sys file h and st_blocks in struct stat DUSG If you have System V ANSI C string and memory functions and headers sys sysmacros h fcntl h getcwd no valloc and ndir h unless you use DDIRENT DNO MEMORY H If USG or STDC HEADERS but do not include memory h DDIRENT If USG and you have dirent h instead of ndir h DSIGTYPE int If your signal handlers return int not void DNO MTIO If you lack sys mtio h magtape ioctls DNO REMOTE If you do not have a remote shell or rexec DUSE REXEC To use rexec for remote tape operations instead of forking rsh or remsh DVPRINTF MISSING If you lack vprintf function but have doprnt DDOPRNT MISSING If you lack doprnt function Also need to define DVPRINTF MISSING you lack ftime system call trstr function DF TIME MISSING DSTRSTR MISSING DVALLOC MISSING DMKDIR MISSING you lack s you lack valloc function you lack mkdir and mdir system calls
56. in every invocation of the C compiler both those which do compilation and those which do linking Every Makefile should define the variable INSTALL which is the basic command for installing a file into the system Every Makefile should also define the variables INSTALL PROGRAM and INSTALL DATA The default for each of these should be INSTALL Then it should use those variables as the commands for actual installation for executables and non executables respectively Use these variables as follows S INSTALL PROGRAM foo S bindir foo 5 5 DATA libfoo a libdir libfoo a Optionally you may add the value of DESTDIR to the target filename Doing this allows the installer to create a snapshot of the installation to be copied onto the real target filesystem later Do not set the value of DESTDIR in your Makefile and do not include it in any installed files With support for DESTDIR the above examples become S INSTALL PROGRAM foo S DESTDIR S S INSTALL DATA libfoo a DESTDIR libdir libfoo a Always use a file name not a directory name as the second argument of the installation commands Use a separate command for each file to be installed 4 ST9 gmake Reference Manual 14 Makefile Conventions 14 4 Variables for installation directories Installation directories should always be named by variables so
57. is to update the executable program 7 therefore we put that rule first 13 185 2 Introduction to Makefiles ST9 gmake Reference Manual 2 4 14 185 Thus when you give the command make make reads the makefile in the current directory and begins by processing the first rule In the example this rule is for relinking edit but before make can fully process this rule it must process the rules for the files that edit depends on which in this case are the object files Each of these files is processed according to its own rule These rules say to update each o file by compiling its source file The recompilation must be done if the source file or any of the header files named as prerequisites is more recent than the object file or if the object file does not exist The other rules are processed because their targets appear as prerequisites of the goal If some other rule is not depended on by the goal or anything it depends on etc that rule is not processed unless you tell make to do so with a command such as make clean Before recompiling an object file make considers updating its prerequisites the source file and header files This makefile does not specify anything to be done for them the c and h files are not the targets of any rules so make does nothing for these files But make would update automatically generated C programs such as those made by Bison or Yacc by their own rules at this time After recompili
58. is used see Chapter 11 Updating Archive Files on page 133 123 185 10 Implicit Rules ST9 gmake Reference Manual 124 185 The names of all the prerequisites with spaces between them For prerequisites which are archive members only the member named is used see Chapter 11 Updating Archive Files on page 133 A target has only one prerequisite on each other file it depends on no matter how many times each file is listed as a prerequisite So if you list a prerequisite more than once for a target the value of con tains just one copy of the name 4 This is like but prerequisites listed more than once are dupli cated in the order they were listed in the makefile This is primarily useful for use in linking commands where it is meaningful to repeat library file names in a particular order 5 The stem with which an implicit rule matches see Section 10 5 4 How patterns match on page 126 If the target is dir a foo b and the target pattern is a then the stem is dir foo The stem is useful for constructing names of related files In a static pattern rule the stem is part of the file name that matched the in the target pattern In an explicit rule there is no stem so cannot be determined in that way Instead if the target name ends with a recognized suffix see Section 10 7 Old fashioned suffix rules on page 129 is set to the target name minus the suffix For example if the target name is oo c t
59. it is easy to install in a nonstandard place The standard names for these variables are described below They are based on a standard filesystem layout variants of it are used in SVR4 4 4BSD Linux Ultrix v4 and other modern operating systems These two variables set the root for the installation All the other installation directories should be subdirectories of one of these two and nothing should be directly installed into these two directories prefix A prefix used in constructing the default values of the variables listed below The default value of prefix should be usr local When building the complete GNU system the prefix will be empty and usr will be a symbolic link to If you are using Autoconf write it as Running make install With a different value of prefix from the one used to build the program should NOT recompile the program exec prefix A prefix used in constructing the default values of some of the variables listed below The default value of exec prefix should be prefix If you are using Autoconf write it as Qexec prefixQ Generally exec prefix is used for directories that contain machine specific files such as executables and subroutine libraries while prefix is used directly for other directories Running make install with a different value of exec prefix from the one used to build the program should NOT recompile the program Executable programs are installed in one
60. like this TARGET VARIABLE ASSIGNMENT 75 185 6 How to Use Variables ST9 gmake Reference Manual Note 6 11 76 185 or like this TARGET override VARIABLE ASSIGNMENT Multiple TARGET values create a target specific variable value for each member of the target list individually The VARIABLE ASSIGNMENT can be any valid form of assignment recursive static appending or conditional All variables that appear within the VARTABLE ASSIGNMENT are evaluated within the context of the target thus any previously defined target specific variable values will be in effect This variable is actually distinct from any global value the two variables do not have to have the same flavor recursive vs static Target specific variables have the same priority as any other makefile variable Variables provided on the command line and in the environment if the option is in force will take precedence Specifying the override directive will allow the target specific variable value to be preferred There is one more special feature of target specific variables when you define a target specific variable that variable value is also in effect for all prerequisites of this target unless those prerequisites override it with their own target specific variable value So for example a statement like this prog CFLAGS g prog prog o foo o bar o will
61. line in the makefile that looks like this include FILENAMES FILENAMES can contain shell file name patterns Extra spaces are allowed and ignored at the beginning of the line but a tab is not allowed If the line begins with a tab it will be considered a command line Whitespace is required between include and the file names and between file names extra whitespace is ignored there and at the end of the directive A comment starting with is allowed at the end of the line If the file names contain any variable or function references they are expanded See Chapter 6 How to Use Variables on page 63 4 5 9 gmake Reference Manual 3 Writing Makefiles 4 For example if you have three mk files a mk b mk and c mk bar expands to bish bash then the following expression include foo mk bar is equivalent to include foo a mk b mk c mk bish bash When make processes an include directive it suspends reading of the containing makefile and reads from each listed file in turn When that is finished make resumes reading the makefile in which the directive appears One occasion for using include directives is when several programs handled by individual makefiles in various directories need to use a common set of variable definitions see Section 6 5 Setting variables on page 70 or pattern rules see Section 10 5 Defining and redefining pattern rules on page 121 Another such occasion
62. most shells it does command expansion This means that it takes an argument that is a shell command and returns the output of the command The only processing make does on the result before substituting it into the surrounding text is to convert each newline or carriage return newline pair to a single space It also removes the trailing carriage return and newline if it s the last thing in the result The commands run by calls to the sne11 function are run when the function calls are expanded In most cases this is when the makefile is read in The exception is that function calls in the commands of the rules are expanded when the commands are run and this applies to she11 function calls like all others Here are some examples of the use of the sne11 function contents shell cat foo Sets contents to the contents of the file oo with a space rather than a newline separating each line files shell echo c sets files to the expansion of c Unless make is using a very strange shell this has the same result as wildcard c Functions that control make These functions control the way make runs Generally they are used to provide information to the user of the makefile or to cause make to stop if some sort of environmental error is detected error TEXT Generates a fatal error where the message is TEXT Note that the error is generated whenever this function is evaluated So if you put it inside
63. not apply unless its prerequisites actually exist Prerequisites that could be made with other implicit rules are not good enough In other words no further chaining is allowed beyond a terminal rule For example the built in implicit rules for extracting sources from RCS and SCCS files are terminal as a result if the file oo c v does not exist make will not even consider trying to make it as an intermediate file from foo c v o or from RCS SCCS s foo c v RCS and SCCS files are generally ultimate source files which should not be remade from any other files therefore make can save time by not looking for ways to remake them If you do not mark the match anything rule as terminal then it is non terminal A non terminal match anything rule cannot apply to a file name that indicates a specific type of data A file name indicates a specific type of data if some non match anything implicit rule target matches it For example the file name foo c matches the target for the pattern rule c the rule to run Yacc Regardless of whether this rule is actually applicable which happens only if there is a file oo y the fact that its target matches is enough to prevent consideration of any non terminal match anything rules for the oo c Thus make will not even consider trying to make as an executable from etc The motivation for this constraint is that non terminal match any
64. not need to use this feature with RCS We recommend that you avoid using of SCCS RCS is widely held to be superior and is also free By choosing free software in place of comparable or inferior proprietary software you support the free software movement Usually you want to change only the variables listed above which are documented in the following section However the commands in built in implicit rules actually use variables such as COMPILE c LINK p and PREPROCESS S whose values contain the commands listed above r ST9 gmake Reference Manual 10 Implicit Rules 10 3 4 make follows the convention that the rule to compile a source uses the variable COMPILE X Similarly the rule to produce an executable from a x file uses LINK X and the rule to preprocess a x file uses PREPROCESS X Every rule that produces an object file uses the variable OUTPUT OPTION make defines this variable either to contain 58 or to be empty depending compile time option You need the o option to ensure that the output goes into the right file when the source file is in a different directory as when using VPATH see Section 4 4 3 How directory searches are performed on page 33 However compilers on some systems do not accept a o switch for object files If you use such a system and use VPATH some compilations will put their output in the wrong place A possible workaround fo
65. o 58 would cause the command oo c usr lib libcurses a o footobe executed when foo is older than oo c orthan usr lib libcurses a Although the default set of files to be searched for is 1ibNAME so and libNAME a this is customizable via the 5 variable Each word in the value of this variable is a pattern string When a prerequisite like 1 is seen make will replace the percent in each pattern in the list with NAME and perform the above directory searches using that library filename If no library is found the next word in the list will be used The default value for LIBPATTERNS is lib so 1ib a which provides the default behavior described above You can turn off link library expansion completely by setting this variable to an empty value Phony targets A phony target is one that is not really the name of a file It is just a name for some commands to be executed when you make an explicit request There are two reasons to use a phony target to avoid a conflict with a file of the same name and to improve performance If you write a rule whose commands will not create the target file the commands will be executed every time the target comes up for remaking Here is an example clean rm o temp Because the rm command does not create a file named clean probably no such file will ever exist Therefore the xm command will be executed every time you say make
66. office nearest you Contact list Note 3 For American Canadian customers seeking technical support the US Canada is split in 3 territories According to your area contact the following sales office and ask to be transferred to an 8 bit microcontroller Field Applications Engineer FAE Canada and East Coast STMicroelectronics Lexington Corporate Center 10 Maguire Road Building 1 3rd floor Lexington MA 02421 Phone 781 402 2650 Mid West STMicroelectronics 1300 East Woodfield Road Suite 410 Schaumburg IL 60173 Phone 847 585 3000 West coast STMicroelectronics Inc 28202 Cabot Road Suite 650 Laguna Niguel CA Phone 949 347 0717 Europe France 33 1 47407575 Germany 49 89 460060 U K 44 1628 890800 Asia Pacific Region 177 185 Product Support 178 185 Japan 81 3 3280 4120 Hong Kong 852 2861 5700 Sydney 61 2 9580 3811 Taipei 886 2 2378 8088 ST9 gmake Reference Manual 4 Index Symbols DEFAULT 40 DELETE 40 EXPORT ALL VARIABLES 41 E ees rere 41 INTERMEDIATE 40 PHONY ette geo 39 139 PRECIOUS 5 enis DERE 40 SECONDARY 40 JN ZEE 41 SUFFIXE S 40 2
67. on command lines and what syntax they use When the shell is bin sh a starts a comment that extends to the end of the line The 4 does not have to be at the beginning of a line Text on a line before a is not part of the comment Command echoing Normally make prints each command line before it is executed We call this echoing because it gives the appearance that you are typing the commands yourself When line starts with the echoing of that line is suppressed is discarded before the command is passed to the shell Typically you would use this for a command whose only effect is to print something such as an echo command to indicate progress through the makefile echo About to make distribution files When make is given the flag n or just print it only echoes commands it won t execute them See Section 9 7 Summary of options on page 106 for more information In this case and only this case even the commands starting with are printed This flag is useful for finding out which commands make thinks are necessary without actually doing them The s or silent flag to make prevents all echoing as if all commands started with A rule in the makefile for the special target SILENT without prerequisites has the same effect see Section 4 8 Special built in target names on page 39 SILENT is essentially obsolete since is more flexible 49 185 5 Writing Commands Rules ST9
68. on page 41 The COMMAND lines start with a tab character The first command may appear on the line after the prerequisites with a tab character or may appear on the same line with a semicolon Either way the effect is the same See Chapter 5 Writing Commands in Rules on page 49 Because dollar signs are used to start variable references if you really want a dollar sign a rule you must write two of them see Chapter 6 How to Use Variables on page 63 You may split a long line by inserting a backslash followed by a newline but this is not required as make places no limit on the length of a line in a makefile A rule tells make two things when the targets are out of date and how to update them when necessary The criterion for being out of date is specified in terms of the PREREQUISITES which consist of file names separated by spaces Wildcards and archive members see Chapter 11 Updating Archive Files on page 133 are allowed here too A target is out of date if it does not exist or if it is older than any of the prerequisites by comparison of last modification times The idea is that the contents of the target file are computed based on information in the prerequisites so if any of the prerequisites changes the contents of the existing target file are no longer necessarily valid How to update is specified by COMMANDS These are lines to be executed by the shell normally sh but with some extra
69. run by default Thus in the example makefile we want the rule for edit which recompiles the editor to remain the default goal Since clean is not a prerequisite of edit this rule will not run at all if we give the command make with no arguments In order to make the rule run we have to type make clean Refer to Section 9 How to Run Make on page 99 for more information 17 185 2 Introduction to Makefiles 18 185 ST9 gmake Reference Manual 4 5 9 gmake Reference Manual 3 Writing Makefiles 3 1 3 WRITING MAKEFILES The information that tells make how to recompile a system comes from reading a data base called the makefile What makefiles contain Makefiles contain five kinds of things explicit rules implicit rules variable definitions directives and comments Rules variables and directives are described at length in later chapters An explicit rule says when and how to remake one or more files called the rule s targets It lists the other files that the targets depend on call the prerequisites of the target and may also give commands to use to create or update the targets See Section 4 Writing Rules on page 27 An implicit rule says when and how to remake a class of files based on their names It describes how a target may depend on a file with a name similar to the target and gives commands to create or update such a target See Section 10 1 Using implicit rules on page 111 A variable
70. set CFLAGS to g in the command script for prog but it will also set CFLAGS to g in the command scripts that create prog o and bar o and any command scripts which create their prerequisites Pattern specific variable values In addition to target specific variable values see Section 6 10 Target specific variable values on page 75 GNU make supports pattern specific variable values In this form a variable is defined for any target that matches the pattern specified Variables defined in this way are searched after any target specific variables defined explicitly for that target and before target specific variables defined for the parent target Set a pattern specific variable value like this PATTERN VARIABLE ASSIGNMENT or like this PATTERN override VARIABLE ASSIGNMENT where PATTERN is a pattern As with target specific variable values multiple PATTERN values create a pattern specific variable value for each pattern individually The VARIABLE ASSIGNMENT can be any valid form of assignment r ST9 gmake Reference Manual 6 How to Use Variables Any command line variable setting will take precedence unless override is specified For example 9 0 CFLAGS will assign CFLAGS the value of o for all targets matching the pattern 4 77 185 6 How to Use Variables 78 185 ST9 gmake Reference Manual 4 ST9 gmake Ref
71. string must match the file name of a prerequisite that is being searched for the character matching any sequence of zero or more characters as in pattern rules see Section 10 5 Defining and redefining pattern rules page 121 For example h matches files that end in n If there is no the pattern must match the prerequisite exactly which is not useful very often r 5 9 gmake Reference Manual 4 Writing Rules 4 4 3 4 characters in vpath directive s pattern be quoted with preceding backslashes Backslashes that would otherwise quote characters can be quoted with more backslashes Backslashes that quote characters or other backslashes are removed from the pattern before it is compared to file names Backslashes that are not in danger of quoting characters go unmolested When a prerequisite fails to exist in the current directory if the PATTERN in a vpath directive matches the name of the prerequisite file then the DIRECTORIES in that directive are searched just like and before the directories in the vPATH variable For example vpath h headers tells make to look for any prerequisite whose name ends in n in the directory headers if the file is not found in the current directory If several vpath patterns match the prerequisite file s name then make processes each matching vpath directive one by one searching all the directories mentioned in each directive
72. supply options to the program Append FLAGS to the program name variable name to get the options variable name for example BISONFLAGS The names CFLAGS for the C compiler YF LAGS for yacc and LFLAGS for lex are exceptions to this rule but we keep them because they are standard Use CPPFLAGS in any compilation command that runs the preprocessor and use LDFLAGS in any compilation command that does linking as well as in any direct use of 1a If there are C compiler options that must be used for proper compilation of certain files do not include them in CFLAGS Users expect to be able to specify CFLAGS freely themselves Instead arrange to pass the necessary options to the C compiler independently of CFLAGS by writing them explicitly in the compilation commands or by defining an implicit rule like this CFLAGS g ALL CFLAGS CFLAGS eO uo 5 c CPPFLAGS ALL_CFLAGS lt Do include the g option CFLAGS because that is not required for proper compilation You can consider it a default that is only recommended If the package 145 185 14 Makefile Conventions ST9 gmake Reference Manual 146 185 is set up so that it is compiled with GCC by default then you might as well include o in the default value of CFLAGS as well Put CFLAGS last in the compilation command after other variables containing compiler options so the user can use CFLAGS to override the others CFLAGS should be used
73. targets can have prerequisites When one directory contains multiple programs it is most convenient to describe all of the programs in one makefile Makefile Since the target remade by default will be the first one in the makefile it is common to make this a phony target named all and give it as prerequisites all the individual programs For example all progl prog2 prog3 PHONY all progl progl o utils o cc progl progl o utils o prog2 prog2 o cc prog2 prog2 o prog3 prog3 o sort o utils o cc o prog3 prog3 o sort o utils o Now you can say just make to remake all three programs or specify as arguments the ones to remake as in make 1 prog3 When one phony target is a prerequisite of another it serves as a subroutine of the other For example here make cleanall will delete the object files the difference files and the file program PHONY cleanall cleanobj cleandiff cleanall cleanobj cleandiff rm program cleanobj rm o cleandiff rm diff Rules without commands or prerequisites If a rule has no prerequisites or commands and the target of the rule is a nonexistent file then make imagines this target to have been updated whenever its rule is run This implies that all targets depending on this one will always have their commands run An example will illustrate this clean FORCE rm objects FORCE 4 5 9 gmake Reference Manual 4 Writing Rules 4
74. the command frobnicate gt foo If you Say make bar make will find no way to make bar in GNUmakefile so it will use the commands from the pattern rule make f Makefile bar If Makefile provides a rule for updating bar make will apply the rule And likewise for any other target that GNUmakefile does not say how to make 4 5 9 gmake Reference Manual 3 Writing Makefiles 3 7 3 7 1 4 way this works is that the pattern rule has a pattern of just so it matches target whatever The rule specifies a prerequisite force to guarantee that the commands will be run even if the target file already exists We give force target empty commands to prevent make from searching for an implicit rule to build it otherwise it would apply the same match anything rule to force itself and create prerequisite loop How make reads a makefile GNU make does its work in two distinct phases During the first phase it reads all the makefiles included makefiles etc and internalizes all the variables and their values implicit and explicit rules and constructs a dependency graph of all the targets and their prerequisites During the second phase make uses these internal structures to determine what targets will need to be rebuilt and to invoke the rules necessary to do so Its important to understand this two phase approach because it has a direct impact on how variable and function expansion happens this is often a source of some
75. the makefile objects main o kbd o command o display o insert o search o files o utils o Then each place we want to put a list of the object file names we can substitute the variable s value by writing objects see Chapter 6 How to Use Variables on page 63 Here is how the complete simple makefile looks when you use a variable for the object files objects main o kbd o command o display o insert o search o files o utils o edit objects cc o edit objects main o main c defs h main c kbd c defs h command h kbd c command o command c defs h command h command c display o display c defs h buffer h c display c insert o insert c defs h buffer h cc c insert c search o search c defs h buffer h c search c files o files c defs h buffer h command h ce c files c utils o utils c defs h g bils c clean rm edit objects Letting make deduce the commands It is not necessary to spell out the commands for compiling the individual C source files because make can figure them out it has an implicit rule for updating file from a correspondingly named c file using a c command For example it will use the command cc c main c o main o to compile main c into main o We can therefore omit the commands from the rules for the object files See Section 10 1 Using implicit rules on page 111 for more information 15
76. the variable s old value contains variable references Take this common example CFLAGS includes O CFLAGS pg enable profiling The first line defines the CFLAGS variable with a reference to another variable includes CFLAGS is used by the rules for C compilation see Section 10 2 Catalog of implicit rules on page 113 for more information Using for the ky ST9 gmake Reference Manual 6 How to Use Variables 6 7 3 definition makes CFLAGS recursively expanded variable meaning includes O is not expanded when make processes the definition of CFLAGS Thus includes need not be defined yet for its value to take effect It only has to be defined before any reference to CFLAGS If we tried to append to the value of CFLAGS without using we might do it like this CFLAGS CFLAGS enable profiling This is pretty close but not quite what we want Using redefines CFLAGS as a simply expanded variable this means make expands the text CFLAGS pg before setting the variable If includes is not yet defined we get O pg anda later definition of includes will have no effect Conversely by using we set CFLAGS to the unexpanded value includes O pg Thus we preserve the reference to includes so if that variable gets defined at any later point a reference like CFLAGS still uses its value The override directive If a variable has been set with a command argument see Section
77. this will not change them again since they are already up to date If you know that one or more of your makefiles cannot be remade and you want to keep make from performing an implicit rule search on them perhaps for efficiency reasons you can use any normal method of preventing implicit rule lookup to do so For example you can write an explicit rule with the makefile as the target and an empty command string see Section 5 8 Using empty commands on page 62 for more information If the makefiles specify a double colon rule to remake a file with commands but no prerequisites that file will always be remade see Section 4 12 Double colon rules on page 45 In the case of makefiles a makefile that has a double colon rule with commands but no prerequisites will be remade every time make is run and then again after make starts over and reads the makefiles in again This would cause an infinite loop make would constantly remake the makefile and never do anything else So to avoid this make will not attempt to remake makefiles which are specified as targets of a double colon rule with commands but no prerequisites If you do not specify any makefiles to be read with or fi le options make will try the default makefile names see Section 3 2 What name to give your makefile on page 20 Unlike makefiles explicitly requested with or file options make is not certain that these makefiles should exist However if a default mak
78. update the target file A tab character must come at the beginning of every command line to distinguish commands lines from other lines in the makefile Bear in mind that make does not know anything about how the commands work It is up to you to supply commands that will update the target file properly All make does is execute the commands in the rule you have specified when the target file needs to be updated The target clean is not a file but merely the name of an action Since you normally do not want to carry out the actions in this rule clean is not a prerequisite of any other rule Consequently make never does anything with it unless you tell it specifically This rule not only is not a prerequisite it also does not have any prerequisites so the only purpose of the rule is to run the specified commands Targets that do not refer to files but are just actions are called phony targets See Section 4 5 Phony targets on page 36 for information about this kind of target See Section 5 4 Errors in commands on page 53 to see how to cause make to ignore errors from xm or any other command How make processes a makefile By default make starts with the first target not targets whose names start with This is called the default goal Goals are the targets that make strives ultimately to update See Section 9 2 Arguments to specify the goals on page 99 In the simple example of the previous section the default goal
79. utilities oL Im Eas 144 Variable eite t eed 22 variable 25 Valiables eet needs 14 MAKEFLEAQGS acini ees eee ee 56 ci bonc teen 118 Mand ice eter e edes 151 MAN OX hera Pete teni eta 151 Inan28xt eios 152 MAN OI sete ect ert poe Petre 151 151 Modula 2 programs c ee eng 114 Multiple rules for one 42 Multiple 41 N E E E 137 alo e pep 89 STA 139 old file 2 ie ieee das 139 oldincludedir ssssssssssss 151 Options 5 2 1 110 0 204222 107 s A 106 stetit See testbeds E 106 gites 106 debug 106 0422 106 2 1 nnne 107 OLD OE Pai E Erat 106 environment 106 106 106 106 sep det RE 106 tI IEEE 107 106 ignore errors sese 106 naene nnee ee 107
80. variable Double and simple quotes The use of double quotes for example within a variable may cause problems on Windows 95 and Windows 98 The use of simple quotes instead of double quotes should work around the problem For example in a makefile do not write FLAGS where APPLI is another variable defined in the makefile but write FLAGS Wl Map APPLI map About the ST9 toolchain documentation set The ST9 toolchain documentation set is comprised of the following 579 9 Libraries amp Startup Files Reference Manual ST9 ELF as9 109 amp Binutils Reference Manual 9 185 1 Introduction ST9 gmake Reference Manual 1 6 1 7 10 185 e 5 9 User Manual ST9 V4 to V6 Migration Notes e ST94 gmake Reference Manual e STVD On line Help About this manual The following conventions are used in this manual Bold type Used to emphasize new or special terminology tool names and product names Teletype Used to distinguish command line examples code fragments and program listings from normal text Blue italicized Used to indicate a cross reference you can link directly to the reference by clicking on it while viewing with Acrobat Reader Italic type Used to indicate book titles Braces Used to denote optional items in command syntax Brackets Used in command syntax to denote optional items on the command line El
81. with this definition There is another assignment operator for variables This is called a conditional variable assignment operator because it only has an effect if the variable is not yet defined This statement FOO bar is exactly equivalent to this see Section 8 7 The origin function on page 95 ifeq 5 FOO undefined bar endif A variable set to an empty value is still defined so will not set that variable 4 ST9 gmake Reference Manual 6 How to Use Variables 6 3 6 3 1 6 3 2 4 Advanced features for reference to variables This section describes some advanced features you can use to reference variables in more flexible ways Substitution references A substitution reference substitutes the value of a variable with alterations that you specify It has the form VAR A B VAR A B and its meaning is to take the value of the variable VAR replace every A at the end of a word with B in that value and substitute the resulting string When we say at the end of a word we mean that A must appear either followed by whitespace or at the end of the value in order to be replaced other occurrences of A in the value are unaltered For example foo b o bar f00 0 c Sets bar t0a c b c c c See Section 6 5 Setting variables on page 70 A substitution reference is actually an abbreviation for use of the patsubst expansion function see S
82. 4 Makefile Conventions 14 14 1 4 MAKEFILE CONVENTIONS This node describes conventions for writing the Makefiles for GNU programs Using Automake will help you write a Makefile that follows these conventions General conventions for makefiles Every Makefile should contain this line SHELL bin sh to avoid trouble on systems where the SHELL variable might be inherited from the environment This is never a problem with GNU make Different make programs have incompatible suffix lists and implicit rules and this sometimes creates confusion or misbehavior So it is a good idea to set the suffix list explicitly using only the suffixes you need in the particular Makefile like this SUFFIXES SUFFIXES C The first line clears out the suffix list the second introduces all suffixes which may be subject to implicit rules in this Makefile Don t assume that is in the path for command execution When you need to run programs that are a part of your package during the make please make sure that it uses if the program is built as part of the make or srcdir if the file is an unchanging part of the source code Without one of these prefixes the current search path is used The distinction between the build directory and srcdir the source directory is important because users can build in a separate directory using the srcdir option to configure A rule of the form foo 1 foo man se
83. 4 How pat terns match on page 126 Kae eaor anane nemano Treason renane ecu Tearen maana ie tein te Reesor santo The directory part and the file within directory part of The directory part and the file within directory part of scm sem The directory part and the file within directory part of 58 5 5 lt 5 CD 5 GF D S F D SF D lt F D S F 0 F 20 S F 4 165 185 Appendix Quick Reference ST9 gmake Reference Manual The following table summarizes the variables that GNU make understands MAKEFILES Makefiles to be read on every invocation of make See Section 3 4 The vari able MAKEFILES on page 22 VPATH Directory search path for files not found in the current directory See Section 4 4 1 VPATH search path for all prerequisites on page 31 SHELL The name of the system default command interpreter usually bin sh You can set SHELL in the makefile to change the shell used to run commands See Sec tion 5 2 Command execution on page 50 On MS DOS only the name of the command interpreter that is to be used by make This value takes precedence over the value of SHELL The name with which make was invoked Using this variable in commands has special meaning See Section 5 6 1 How the MAKE variable works on page 55 The number of leve
84. 6 2 The two flavors of variables on page 64 for an explanation of the two flavors of variables When you add to a variable s value with make acts essentially as if you had included the extra text in the initial definition of the variable If you defined it first with making it a simply expanded variable adds to that simply expanded definition and expands the new text before appending it to the old value just as does see Section 6 5 Setting variables on page 70 for a full explanation of In fact variable value variable more is exactly equivalent to variable value variable variable more On the other hand when you use with a variable that you defined first to be recursively expanded using plain make does something a bit different Recall that when you define a recursively expanded variable make does not expand the value you set for variable and function references immediately Instead it stores the text verbatim and saves these variable and function references to be expanded later when you refer to the new variable see Section 6 2 The two flavors of variables on page 64 When you use on a recursively expanded variable it is this unexpanded text to which make appends the new text you specify variable value variable more is roughly equivalent to temp value variable temp more except that of course it never defines a variable called temp The importance of this comes when
85. 9 Gata Gites 148 exec prefix o net det ore rende 147 FG M 118 FEEAGSz dne Cate Pli 119 64 for installation directories 147 for specifying commands 145 GET zt eps odisea 118 GELA GS it tidie bis 119 oerte 150 149 EDFEAGS 119 epa 118 FLAGS inann tesoro 119 ies oe t y 149 148 liSpdit iaceret 150 localstatedil interes 149 adus 55 56 dts do em Pee 118 c 151 manText i esc edens tus 151 MANZO 151 2 vanta qus 152 iui ce 151 tret 151 oldincludedir 151 overriding 104 118 PFLAG S ted 119 iicet ette 147 RELAGS eid i omi irit 119 118 148 70 149 183 185 Index s 56
86. 9 5 Overriding variables on page 104 then ordinary assignments in the makefile are ignored If you want to set the variable in the makefile even though it was set with a command argument you can use an override directive which is a line that looks like this override VARIABLE VALUE or override VARIABLE VALUE To append more text to a variable defined on the command line use override VARIABLE MORE TEXT See Section 6 6 Appending more text to variables on page 71 The override directive was not invented for escalation in the war between makefiles and command arguments It was invented so you can alter and add to values that the user specifies with command arguments For example suppose you always want the g switch when you run the compiler but you would like to allow the user to specify the other switches with a command argument just as usual You could use this override directive override CFLAGS g You can also use override directives with define directives This is done as you might expect override define foo bar endef See Section 6 8 Defining variables verbatim on page 74 73 185 6 How to Use Variables ST9 gmake Reference Manual 6 8 6 9 74 185 Defining variables verbatim Another way to set the value of a variable is to use the define directive This directive has an unusual syntax which allows newline characters to be included in the value which is convenie
87. ANSFORM TEXT Functions allow you to do text processing in the makefile to compute the files to operate on or the commands to use You use a function in a function call where you give the name of the function and some text the arguments for the function to operate on The result of the function s processing is substituted into the makefile at the point of the call just as a variable might be substituted Function call syntax A function call resembles a variable reference It looks like this 5 FUNCTION ARGUMENTS or like this FUNCTION ARGUMENTS Here FUNCTION is a function name one of a short list of names that are part of make You can also essentially create your own functions by using the 11 built in function The ARGUMENTS are the arguments of the function They are separated from the function name by one or more spaces or tabs and if there is more than one argument then they are separated by commas Such whitespace and commas are not part of an argument s value The delimiters which you use to surround the function call whether parentheses or braces can appear in an argument only in matching pairs the other kind of delimiters may appear singly If the arguments themselves contain other function calls or variable references it is wisest to use the same kind of delimiters for all the references write subst a b x not subst a b x This is because it is clearer and because only one
88. DJGPP tree hierarchy 21 185 3 Writing Makefiles ST9 gmake Reference Manual 3 4 3 5 22 185 If you want make to simply ignore a makefile which does not exist and cannot be remade with no error message use the include directive instead of include like this include FILENAMES This is acts like include in every way except that there is no error not even a warning if any of the FILENAMES do not exist For compatibility with some other make implementations sinclude is another name for include The variable MAKEFILES If the environment variable MAKEFILES is defined make considers its value as a list of names separated by whitespace of additional makefiles to be read before the others This works much like the include directive various directories are searched for those files see Section 3 3 Including other makefiles on page 20 In addition the default goal is never taken from one of these makefiles and it is not an error if the files listed in MAKEFILES are not found main use of MAKEFILES is in communication between recursive invocations of make see Section 5 6 Hecursive use of make on page 55 It usually is not desirable to set the environment variable before a top level invocation of make because it is usually better not to mess with a makefile from outside However if you are running make without a specific makefile a makefi
89. EFAULT but you also do not want any commands to be run for the target you can give it empty commands see Section 5 8 Using empty commands on page 62 for more information 4 ST9 gmake Reference Manual 10 Implicit Rules 10 7 3 You can use a last resort rule to override part of another makefile See Section 3 6 Overriding part of another makefile on page 24 Old fashioned suffix rules Suffix rules are the old fashioned way of defining implicit rules for make Suffix rules are obsolete because pattern rules are more general and clearer They are supported in GNU make for compatibility with old makefiles They come in two kinds double suffix and single suffix A double suffix rule is defined by a pair of suffixes the target suffix and the source suffix It matches any file whose name ends with the target suffix The corresponding implicit prerequisite is made by replacing the target suffix with the source suffix in the file name A two suffix rule whose target and source suffixes are o and c is equivalent to the pattern rule o A single suffix rule is defined by a single suffix which is the source suffix It matches any file name and the corresponding implicit prerequisite name is made by appending the source suffix A single suffix rule whose source suffix is c is equivalent to the pattern rule Suffix rule definitions are recognized by comparing each rule s target against a defined list of kn
90. HELL Will not be changed and thus the line that sets it will be effectively ignored This is so make will only support features specific to a Unix style shell if such a shell is actually installed on the system where make runs This extended search for the shell is limited to the cases where SHELL is set from the Makefile if it is set in the environment or command line you are expected to set it to the full pathname of the shell exactly as things are on Unix The effect of the above DOS specific processing is that a Makefile that says SHELL bin sh as many Unix makefiles do will work on MS DOS unaltered if you have e g sh exe installed in some directory along your PATH Unlike most variables the variable SHELL is never set from the environment This is because the SHELL environment variable is used to specify your personal choice of shell program for interactive use It would be very bad for personal choices like this to affect the functioning of makefiles See Section 6 9 Variables from the environment on page 74 However on MS DOS and MS Windows the value of SHELL in the environment is used since on those systems most users do not set this variable and therefore it is most likely set specifically to be used by make On MS DOS if the setting of SHELL is not suitable for make you can set the variable MAKESHELL to the shell that make should use this will override the value of SHELL Parallel exe
91. LACEMENT VAR The second shorthand simplifies one of the most common uses of patsubst replacing the suffix at the end of file names VAR SUFFIX REPLACEMENT is equivalent to patsubst SUFFIX SREPLACEMENT 5 VAR For example you might have a list of object files objects foo o bar o baz o To get the list of corresponding source files you could simply write instead of using the general form S patsubst 0 c objects strip STRING Removes leading and trailing whitespace from STRING and replaces each internal sequence of one or more whitespace characters with a single space Thus strip a b resultsina b c The function st rip be very useful when used in conjunction with conditionals When comparing something with the empty string 7 using ifeq or ifneq you usually want a string of just whitespace to match the empty string see Section 7 Conditional Parts of Makefiles on page 79 Thus the following may fail to have the desired results PHONY all ifneq needs made all 5 needs made else all Gecho Nothing to make endif Replacing the variable reference needs made with the function call strip needs made in the ifneg directive would make it more robust findstring FIND IN Searches IN for an occurrence of FIND If it occurs the value is FIND otherwise the value is empt
92. N tex is made from N web with WEAVE or from N w and from N ch if it exists or can be made with CWEAVE N p is made from N web with TANGLE and N c is made from N w and from N ch if it exists or can be made with CTANGLE Texinfo and Info N dvi is made from N texinfo N texi Or N txinfo with the command TEXI2DVI S TEXI2DVI FLAGS N info is made from N texinfo N texi or N txinfo with the command MAKEINFO MAKEINFO FLAGS RCS Any file N is extracted if necessary from an RCS file named either N v or RCS N v The precise command used is COFLAGS N will not be extracted from RCS if it already exists even if the RCS file is newer The rules for RCS are terminal see Section 10 5 5 Match anything pattern rules on page 126 so RCS files cannot be generated from another source they must actually exist SCCS Any file N is extracted if necessary from an SCCS file named either s N or SCCS s N The precise command used is 5 GET 5 GFLAGS The rules for SCCS are terminal see Section 10 5 5 Match anything pattern rules on page 126 so SCCS files cannot be generated from another source they must actually exist For the benefit of SCCS a file N is copied from N sh and made executable by everyone This is for shell scripts that are checked into SCCS Since RCS preserves the execution permission of a file you do
93. OS style separator can be used anywhere in wildcard expansions to quote characters r ST9 gmake Reference Manual 1 Introduction 1 4 2 1 4 3 1 4 4 1 4 5 1 4 6 1 5 4 Driver letter MS Windows and MS DOS driver letter representation uses the character this presents a problem as represents a separator in make So as a workaround make for win32 interprets x as x and not as x and The drawback to this is that a one character directory may be interpreted as a driver letter In this case must be used instead of as the separator is recommended for portability Spaces in pathnames MS Windows allows spaces in file and directory names to be interpreted as separators For example VPATH all sources In this case the 11 sources directory is interpreted as two directories Command separation Commands follow rules depending on the shell used so the possibility of having separate commands on the same line with a separator is a feature which is implemented in the sh shell for example but not in the command com shell The character The character at the beginning of a file name either represents your home directory or the home directory of the user name following it On systems such as MS DOS or MS Windows which don t have a home directory for each user this functionality can be simulated by setting the HOME environment
94. RN REPLACEMENT TEXT Finds whitespace separated words in TEXT that match PATTERN and replaces them with REPLACEMENT Here PATTERN may contain a which acts as a wildcard matching any number of any characters within a word If REPLACEMENT also contains the is replaced by the text that matched the in PATTERN characters in patsubst function invocations can be quoted with preceding backslashes V Backslashes that would otherwise quote characters can be quoted with more backslashes Backslashes that quote characters or other backslashes are removed from the pattern before it is compared file names or has a stem substituted into it Backslashes that are not in danger of quoting characters go unmolested For example the pattern the Sweird pattern has the weird preceding the operative character and pattern following it The final two backslashes are left alone because they cannot affect any character Whitespace between words is folded into single space characters leading and trailing whitespace is discarded For example S patsubst c 0 x c c bar c produces the value x c o bar o Substitution references see Section 6 3 1 Substitution references on page 67 are a simpler way to get the effect of the pat subst function ky ST9 gmake Reference Manual 8 Functions to Transform Text 5 VAR PATTERN REPLACEMENT is equivalent to patsubst PATTERN REP
95. RUE may be any lines of text to be considered as part of the makefile if the condition is true If the condition is false no text is used instead The syntax of a complex conditional is as follows CONDITIONAL DIRECTIVE EXT IF TRUE else EXT IF FALSE endif If the condition is true TEXT IF TRUE is used otherwise TEXT IF FALSE is used instead The TEXT IF FALSE can be any number of lines of text The syntax of the CONDITIONAL DIRECTIVE is the same whether the conditional is simple or complex There are four different directives that test different conditions Here is a list of them ifeq ARG1 ARG2 ARG1 ARG2 ARG1 ARG2 ARG1 2 ifeq ARG1 ARG2 4 80 185 ST9 gmake Reference Manual 7 Conditional Parts of Makefiles Expand all variable references in ARG1 and ARG2 and compare them If they are identical the TExT IF TRUE is effective otherwise the TEXT IF FALSE if any is effective Often you want to test if a variable has a non empty value When the value results from complex expansions of variables and functions expansions you would consider empty may actually contain whitespace characters and thus are not seen as empty However you can use the strip function to avoid interpret
96. ST9 V6 Software Toolchain gmake Reference Manual Helease 6 1 March 2001 Ref DOC ST9V6 GM USE IN LIFE SUPPORT DEVICES OR SYSTEMS MUST BE EXPRESSLY AUTHORIZED STMicroelectronics PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF STMicroelectronics As used herein 1 Life support devices or systems are those which a are intended for surgical implant into the body or b support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided with the product can be reasonably expected to result in significant injury to the user 2 A critical component is any component of a life support device or system whose failure to perform can reasonably be expected to cause the failure of the life support device or system or to affect its safety or effectiveness Chapter 1 2 Chapter 3 Chapter 4 4 14 1 2 1 3 1 4 1 5 1 6 1 7 2 1 2 2 2 3 2 4 2 5 2 6 2 7 3 1 3 2 3 3 3 4 3 5 3 6 3 7 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 Table of Contents Introduction caves oue v COS ER x ORE KURSEN e 7 Preparing and running make neat eee ee 7 How to read this manual 7 Problenis and bugs eed i Oe Re ism epe 8 Limitations of make for WINS eee re ene eee n 8 About the ST9 toolchain documentat
97. SUMIMALY 161 Sy SCONO 149 TANGLEE a eis 118 118 5i 118 used by implicit rules 117 USING ones IDs 63 Values8 iiiter 70 WEAVE tete 118 118 aa a aaa 118 edes 119 zio 139 31 CES 140 WY Ac PE 138 AU C EL 60 184 185 WINING s eii ne 98 tiis 118 WY oT EEUU 116 Wildcard examples essere 29 WildGard 92 Wildcard characters in file NAMES 28 Wildcards pitfalls 0 2 0 a 30 TEE 91 ER ies 91 EE 91 Writing rules 27 less sais Fee eee 118 Yaco for C 115 YAGGOR eae ban sete tom edes 118 VIF LAG St sesh oc ee erates ut ope coetu 119 4 Information furnished is believed to be accurate and reliable However STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result f rom its use No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics Specific
98. Software Updates 177 Contact E a E nt e a ets 177 Index NER PE RD RECEN EE ENS 179 6 185 ky ST9 gmake Reference Manual 1 Introduction 1 1 1 2 4 INTRODUCTION This manual describes GNU make which was implemented by Richard Stallman and Roland McGrath Development since Version 3 76 has been handled by Paul D Smith GNU make conforms to section 6 2 of IEEE Standard 1003 2 1992 POSIX 2 The make utility automatically determines which pieces of a large program need to be recompiled and issues commands to recompile them Our examples show C programs since they are most common but you can use make with any programming language whose compiler can be run with a shell command Indeed make is not limited to programs You can use it to describe any task where some files must be updated automatically from others whenever the others change Preparing and running make To prepare to use make you must write a file called the makefile that describes the relationships among files in your program and provides commands for updating each file In a program typically the executable file is updated from object files which are in turn made by compiling source files Once a suitable makefile exists each time you change some source files this simple shell command make suffices to perform all necessary recompilations The make program uses the ma
99. Variable values of the top level make can be passed to the sub make through the environment by explicit request These variables are defined in the sub make as defaults but do not override what is specified in the makefile used by the sub make makefile unless you use the e switch see Section 9 7 Summary of options on page 106 for more information To pass down or export a variable make adds the variable and its value to the environment for running each command The sub make in turn uses the environment to initialize its table of variable values See Section 6 9 Variables from the environment on page 74 Except by explicit request make exports a variable only if it is either defined in the environment initially or set on the command line and if its name consists only of letters numbers and underscores Some shells cannot cope with environment variable names consisting of characters other than letters numbers and underscores The special variables SHELL and MAKEFLAGS are always exported unless you unexport them MAKEFILES is exported if you set it to anything make automatically passes down variable values that were defined on the command line by putting them in the MAKEFLAGS variable Variables are not normally passed down if they were created by default by make see Section 10 3 r 5 9 gmake Reference Manual 5 Writing Commands in Rules 4 Variables used by implicit rules on page 117 The su
100. ake first checked it The purpose of deleting the target is to make sure that it is remade from scratch when make is next run Why is this Suppose you type Ct r1 c while a compiler is running and it has begun to write an object oo o The Ctri c kills the compiler resulting in an incomplete file whose last modification time is newer than the source oo c But make also receives the Ct xc1 c signal and deletes this incomplete file If make did not do this the next invocation of make would think that oo o did not require updating resulting in a strange error message from the linker when it tries to link an object file half of which is missing You can prevent the deletion of a target file in this way by making the special target PRECIOUS depend on it Before remaking a target make checks to see whether it appears on the prerequisites of PRECIOUS and thereby decides whether the target should be deleted if a signal happens Some reasons why you might do this are that the target is updated in some atomic fashion or exists only to record a r 5 9 gmake Reference Manual 5 Writing Commands in Rules 5 6 Note 5 6 1 3 modification time its contents do not matter or must exist at all times to prevent other sorts of trouble Recursive use of make Recursive use of make means using make as a command in a makefile This technique is useful when you want separate makefiles for various subsystems that
101. already up to date If the exit status is one then some updating needs to be done If make encounters an error the exit status is two so you can distinguish an error from a target that is not up to date 4 ST9 gmake Reference Manual 9 How to Run Make Note 9 4 3 It is an error to use more than one of these three flags in the same invocation of make The n t and q options do not affect command lines that begin with characters or contain the strings MAKE or MAKE Note that only the line containing the character or the strings MAKE or MAKE is run regardless of these options Other lines in the same rule are not run unless they too begin with or contain MAKE or MAKE See Section 5 6 1 How the MAKE variable works on page 55 The w flag provides two features If you also use the n or q flag you can see what make would do if you were to modify some files e Without the n or q flag when make is actually executing commands the w flag can direct make to act as if some files had been modified without actually modifying the files The options and v allow you to obtain other information about make or about the makefiles in use see Section 9 7 Summary of options on page 106 for more information Avoiding recompilation of some files Sometimes you may have changed a source file but you do not want to recompile all the files that depend on it For example suppos
102. am ly empty or g xu rectory to insta tar in 5 prefix bin rectory to insta the info files in prefix info End of system configuration section tar c create c extract c buffer c getoldopt c update c gnu c mangle QO version c list c names c diffarch port c wildmat c getopt c getoptl c regex c getdate y S SRC1 S SRC2 S SRC3 tar o create o extract o buffer o getoldopt o update o gnu o mangle version o list o names o diffarch port o wildmat o getopt o getoptl o regex o getdate o S RTAPELIB OBJ1 OBJ2 OBJ3 README COPYING ChangeLog Makefile in makefile pc configure configure in 173 185 Appendix C Complex Makefile Example ST9 gmake Reference Manual tar texinfo tar info texinfo tex tar h port h open3 h getopt h regex h rmt h rmt c rtapelib c alloca c msd_dir h msd_dir c tcexparg c level 0 1 1 1 backup specs testpad c all tar rmt tar info tar 5 OBJS CC S LDFLAGS o OBJS S LIBS cme Cc 5 5 5 LDFLAGS o rmt c tar info tar texinfo makeinfo tar texinfo install all S INSTALL tar bindir S binprefix tar test rmt S INSTALL rmt etc rmt S INSTALLDATA S srcdir tar info infodir 5 05 tar h port h testpad h regex o buffer o tar o regex h getdate y has 8 shift reduce conflicts testpad h te
103. ams modify while they run This should normally be usr local com but write it as prefix com If you are using Autoconf write it as sharedstatedir The directory for installing data files which the programs modify while they run and that pertain to one specific machine Users should never need to modify files in this directory to configure the package s operation put such configuration information in separate files that go in datadir Or sysconfdir localstatedir should normally be usr local var but write it as prefix var If you are using Autoconf write it as Glocalstatedirg The directory for object files and libraries of object code Do not install executables here they probably ought to go in libexecdir instead The value of 1ibdir should normally be usr local lib but write it exec prefix lib If you are using Autoconf write it as libdir The directory for installing the Info files for this package By default it should be usr local info but it should be written as prefix info lf you are using Autoconf write it as infodir 149 185 14 Makefile Conventions 150 185 lispdir includedir ST9 gmake Reference Manual The directory for installing any Emacs Lisp files in this package By default it should be usr local share emacs site lisp but it should be written as prefix share emacs site lisp If you are using Autoconf write the default a
104. are simply the names of the prerequisites of the special target SUFFIXES You can add your own suffixes by writing a rule for SUFFIXES that adds more prerequisites as in SUFFIXES hack win which adds hack and win to the end of the list of suffixes If you wish to eliminate the default known suffixes instead of just adding to them write a rule for SUFFIXES with no prerequisites By special dispensation this eliminates all existing prerequisites of SUFFIXES You can then write another rule to add the suffixes you want For example SUFFIXES Delete the default suffixes SUFFIXES c o h Define our suffix list The r or no builtin rules flag causes the default list of suffixes to be empty The variable SUFFIXES is defined to the default list of suffixes before make reads any makefiles You can change the list of suffixes with a rule for the special target SUFFIXES but that does not alter this variable Implicit rule search algorithm Here is the procedure make uses for searching for an implicit rule for a target T This procedure is followed for each double colon rule with no commands for each target of ordinary rules none of which have commands and for each prerequisite that is not the target of any rule It is also followed recursively for prerequisites that come from implicit rules in the search for a chain of rules Suffix rules are not mentioned in this alg
105. arget is older than any prerequisites of that rule This can result in executing none any or all of the double colon rules Double colon rules with the same target are in fact completely separate from one another Each double colon rule is processed individually just as rules with different targets are processed The double colon rules for a target are executed in the order they appear in the makefile However the cases where double colon rules really make sense are those where the order of executing the commands would not matter Double colon rules are somewhat obscure and not often very useful they provide a mechanism for cases in which the method used to update a target differs depending on which prerequisite files caused the update and such cases are rare Each double colon rule should specify commands if it does not an implicit rule will be used if one applies See Section 10 1 Using implicit rules on page 111 for more information Generating prerequisites automatically In the makefile for a program many of the rules you need to write often say only that some object file depends on some header file For example if main c uses defs h via an include you would write main o defs h You need this rule so that make knows that it must remake main o whenever defs h changes You can see that for a large program you would have to write dozens of such rules in your makefile And you must always be very careful to update the makefile e
106. ations mentioned in this publication are subject to change without notice This publication supersedes and replaces all information previously supplied STMicroelectronics products are not authorized for use as critical components in life support devices or systems without the express written approval of STMicroelectronics The ST logo is a registered trademark of STMicroelectronics Intel is a U S registered trademark of Intel Corporation Microsoft Windows and Windows NT are U S registered trademarks of Microsoft Corporation 2001 STMicroelectronics All Rights Reserved Purchase of IC Components by STMicroelectronics conveys a license under the Philips Patent Rights to use these components in an system is granted provided that the system conforms to the Standard Specification as defined by Philips STMicroelectronics Group of Companies Australia Brazil China Finland France Germany Hong Kong India Italy Japan Malaysia Malta Morocco Singapore Spain Sweden Switzerland United Kingdom U S A http www st com
107. attern rule contains the character exactly one of them in the target otherwise it looks exactly like an ordinary rule The target is a pattern for matching file names the matches any non empty substring while other characters match only themselves For example as a pattern matches any file name that ends in c s casa pattern matches any file name that starts with s ends in c and is at least five characters long There must be at least one character to match the The substring that the matches is called the stem in a prerequisite of a pattern rule stands for the same stem that was matched by the in the target In order for the pattern rule to apply its target pattern must match the file name under consideration and its prerequisite patterns must name files that exist or can be made These files become prerequisites of the target Thus a rule of the form 0 c COMMAND specifies how to make a file with another file N c as its prerequisite provided that N c exists or can be made There may also be prerequisites that do not use such a prerequisite attaches to every file made by this pattern rule These unvarying prerequisites are useful occasionally A pattern rule need not have any prerequisites that contain or in fact any prerequisites at all Such a rule is effectively a general wildcard It provides a way to make any file that matches the target pattern 121 185 10 Implicit R
108. auses the following lines to be obeyed if the previous conditional failed In the example above this means that the second alternative linking command is used whenever the first alternative is not used It is optional to have an else in a conditional The endif directive ends the conditional Every conditional must end with an endi Unconditional makefile text follows As this example illustrates conditionals work at the textual level the lines of the conditional are treated as part of the makefile or ignored according to the condition This is why the larger syntactic units of the makefile such as rules may cross the beginning or the end of the conditional 4 79 185 7 Conditional Parts of Makefiles ST9 gmake Reference Manual When the variable cc has the value gcc the above example has this effect foo S objects CC o foo objects libs_for_gcc When the variable cc has any other value the effect is this foo objects CC o foo objects normal_libs Equivalent results can be obtained in another way by conditionalizing a variable assignment and then using the variable unconditionally 1 for gcc lgnu normal libs ifeq CC gcc libs libs for else libs normal libs endif foo 5 objects CC o foo objects libs 7 2 Syntax of conditionals The syntax of a simple conditional with no 1 is as follows CONDITIONAL DIRECTIVE TEXT IF TRUE endif The TEXT IF T
109. b make will define these for itself If you want to export specific variables to a sub make use the export directive like this export VARIABLE If you want to prevent a variable from being exported use the unexport directive like this unexport VARIABLE As a convenience you can define a variable and export it at the same time by doing export VARIABLE value has the same result as VARIABLE value export VARIABLE and export VARIABLE value has the same result as VARIABLE value export VARIABLE Likewise export VARIABLE value is just like VARIABLE value export VARIABLE See Section 6 6 Appending more text to variables on page 71 You may notice that the export and unexport directives work in make in the same way they work in the shell sn If you want all variables to be exported by default you can use export by itself export This tells make that variables which are not explicitly mentioned in an export or unexport directive should be exported Any variable given in an unexport directive will still not be exported If you use export by itself to export variables by default variables whose names contain characters that are other than alphanumeric and underscores will not be exported unless specifically mentioned in an export directive The behavior elicited by an export directive by itself was the default in older versions of GNU make If your makefiles depe
110. bar c addprefix PREFIX NAMES The argument NAMES is regarded as a series of names separated by whitespace PREFIX is used as a unit The value of PREFIX is added to the front of each individual name and the resulting larger names are concatenated with single spaces between them For example addprefix src foo bar produces the result src foo src bar 4 ST9 gmake Reference Manual 8 Functions to Transform Text 4 join LIST1 LIST2 Concatenates the two arguments word by word the two first words one from each argument concatenated form the first word of the result the two second words form the second word of the result and so on So the Nth word of the result comes from the Nth word of each argument If one argument has more words that the other the extra words are copied unchanged into the result For example join a b c o produces a c b o Whitespace between the words in the lists is not preserved it is replaced with a single space This function can merge the results of the aix and notdir functions to produce the original list of files which was given to those two functions word N TEXT Returns the Nth word of TExT The legitimate values of N start from 1 If N is bigger than the number of words in TEXT the value is empty For example 5 2 foo bar baz returns bar wordlist S E TEXT Returns the list of words in TEXT starting with word s and ending
111. by implicit rules on page 117 Several special variables are set automatically to a new value for each rule these are called the automatic variables see Section 10 5 3 Automatic variables on page 123 If you d like a variable to be set to a value only if it s not already set then you can use the shorthand operator instead of These two settings of the variable Foo are identical see Section 8 7 The origin function on page 95 FOO bar and ifeq 5 FOO undefined bar endif Appending more text to variables Often it is useful to add more text to the value of a variable already defined You do this with a line containing like this objects another o This takes the value of the variable objects and adds the text another o to it preceded by a single space Thus objects main o foo o bar o utils o objects another o sets objectstOmain o foo o bar o utils o another o Using is similar to objects main o foo o bar o utils o objects objects another o 71 185 6 How to Use Variables ST9 gmake Reference Manual 72 185 but differs in ways that become important when you use more complex values When the variable in question has not been defined before acts just like normal it defines a recursively expanded variable However when there is a previous definition exactly what does depends on what flavor of variable you defined originally See Section
112. cable only one applies the choice depends on the order of rules By contrast a static pattern rule applies to the precise list of targets that you specify in the rule It cannot apply to any other target and it invariably does apply to each of the targets specified If two conflicting rules apply and both have commands that s an error The static pattern rule can be better than an implicit rule for these reasons e You may wish to override the usual implicit rule for a few files whose names cannot be categorized syntactically but can be given in an explicit list f you cannot be sure of the precise contents of the directories you are using you may not be sure which other irrelevant files might lead make to use the wrong implicit rule The choice might depend on the order in which the implicit rule search is done With static pattern rules there is no uncertainty each rule applies to precisely the targets specified Double colon rules Double colon rules are rules written with instead of after the target names They are handled differently from ordinary rules when the same target appears in more than one rule 45 185 4 Writing Rules ST9 gmake Reference Manual 4 13 Note 46 185 When a target appears in multiple rules all the rules must be the same type all ordinary or all double colon If they are double colon each of them is independent of the others Each double colon rule s commands are executed if the t
113. causes rm to continue even if it is unable to remove a file When you run make with the i or ignore errors flag errors are ignored all commands of all rules A rule in the makefile for the special target IGNORE has the same effect if there are no prerequisites These ways of ignoring errors are obsolete because is more flexible When errors are to be ignored because of either a or the i flag make treats an error return just like success except that it prints out a message that tells you the status code the command exited with and says that the error has been ignored When an error happens that make has not been told to ignore it implies that the current target cannot be correctly remade and neither can any other that depends on it either directly or indirectly No further commands will be executed for these targets since their preconditions have not been achieved Normally make gives up immediately in this circumstance returning a nonzero status However if the k or keep going flag is specified make continues to consider the other prerequisites of the pending targets remaking them if 53 185 5 Writing Commands in Rules ST9 gmake Reference Manual 5 5 54 185 necessary before it gives up and returns nonzero status For example after an error in compiling one object file make k will continue compiling other object files even though it already knows that linking them will be impossible See
114. cess and the tar info Info file If you type make install then make not only creates tar rmt and tar info but also installs them If you type make clean then make removes the o files and the tar rmt testpad testpad h and core files If you type make distclean then make not only removes the same files as does make clean but also the TAGS Makefile and config status files Although it is not evident this makefile and config status is generated by the user with the configure program which is provided in the tar distribution but is not shown here If you type make realclean then make removes the same files as does make distclean and also removes the Info files generated from tar texinfo In addition there are targets shar and dist that create distribution kits Generated automatically from Makefile in by configure Un x Makefile for GNU tar program Copyright C 1991 Free Software Foundation Inc This program is free software you can redistribute it and or modify it under the terms of the GNU General Public License SHELL bin sh Start of system configuration section srcdir If you use gcc you should either run the fixincludes script that comes with it or else use gcc with the traditional option Otherwise ioctl calls will be compiled incorrectly on some systems 4 171 185 Appendix C Complex Makefile Example ST9
115. clean The phony target will cease to work if anything ever does create a file named clean in this directory Since it has no prerequisites the file clean would inevitably be considered up to date and its commands would not be executed To avoid this problem you can explicitly declare the target to be phony using the special target PHONY see Section 4 8 Special built in target names on page 39 as follows PHONY clean Once this is done make clean will run the commands regardless of whether there is a file named c1ean 4 5 9 gmake Reference Manual 4 Writing Rules 3 Since it knows that phony targets do not name actual files that could be remade from other files make skips the implicit rule search for phony targets see Chapter 10 Implicit Rules on page 111 This is why declaring a target phony is good for performance even if you are not worried about the actual file existing Thus you first write the line that states that c1ean is a phony target then you write the rule like this PHONY clean clean rm o temp Another example of the usefulness of phony targets is in conjunction with recursive invocations of make In this case the makefile will often contain a variable which lists a number of subdirectories to be built One way to handle this is with one rule whose command is a shell loop over the subdirectories like this SUBDIRS foo bar baz subdirs for dir in SUBDIRS do C S Sdir done
116. confusion when writing makefiles Here we will present a summary of the phases in which expansion happens for different constructs within the makefile We say that expansion is immediate if it happens during the first phase in this case make will expand any variables or functions in that section of a construct as the makefile is parsed We say that expansion is deferred if expansion is not performed immediately Expansion of deferred construct is not performed until either the construct appears later in an immediate context or until the second phase You may not be familiar with some of these constructs yet You can reference this section as you become familiar with them in later chapters Variable assignment Variable definitions are parsed as follows IMMEDIATE DEFERRED IMMEDIATE DEFERRED IMMEDIATE IMMEDIATE IMMEDIATE DEFERRED or IMMEDIATE define IMMEDIATE DEFERRED endef For the append operator the right hand side is considered immediate if the variable was previously set as a simple variable and deferred otherwise 25 185 3 Writing Makefiles ST9 gmake Reference Manual 3 7 2 3 7 3 26 185 Conditional syntax All instances of conditional syntax are parsed immediately in their entirety this includes the ifdef ifeq ifndef and forms Rule definition A rule is always ex
117. ction 14 6 Install command categories on page 157 de db dE db dk uninstall Delete all the installed files the copies that the install target creates This rule should not modify the directories where compilation is done only the directories where files are installed The uninstallation commands are divided into three categories just like the installation commands See Section 14 6 Install command categories on page 157 install Like install but strip the executable files while installing them strip In many cases the definition of this target can be very simple install strip MAKE INSTALL PROGRAM S INSTALL PROGRAM s install Normally we do not recommend stripping an executable unless you are sure the program has no bugs However it can be reasonable to install a stripped executable for actual execution while saving the unstripped executable elsewhere in case there is a bug clean Delete all files from the current directory that are normally created by building the program Don t delete the files that record the configuration Also preserve files that could be made by building but normally aren t because the distribution comes with them Delete dvi files here if they are not part of the distribution distclean Delete all files from the current directory that are created by configuring or building the program If you have unpacked the source and built the program without creating any other files ma
118. cution GNU make knows how to execute several commands at once Normally make will execute only one command at a time waiting for it to finish before executing the next However the j or jobs option tells make to execute many commands simultaneously On MS DOS the 5 option has no effect since that system doesn t support multi processing If the j option is followed by an integer this is the number of commands to execute at once this is called the number of job slots If there is nothing looking like an integer after the j option there is no limit on the number of job slots The 51 185 5 Writing Commands in Rules ST9 gmake Reference Manual 52 185 default number of job slots is one which means serial execution one thing at a time One unpleasant consequence of running several commands simultaneously is that output generated by the commands appears whenever each command sends it so messages from different commands may be interspersed Another problem is that two processes cannot both take input from the same device so to make sure that only one command tries to take input from the terminal at once make will invalidate the standard input streams of all but one running command This means that attempting to read from standard input will usually be a fatal error a Broken pipe signal for most child processes if there are several It is unpredictable which command will have a valid standard input stream whic
119. ding section This is not necessary when using the GNU ar program which updates the ___ SYMDEF member automatically Dangers when using archives It is important to be careful when using parallel execution the j switch see Section 5 3 Parallel execution on page 51 and archives If multiple ar commands run at the same time on the same archive file they will not know about each other and can corrupt the file Possibly a future version of make will provide a mechanism to circumvent this problem by serializing all commands that operate on the same archive file But for the time being you must either write your makefiles to avoid this problem in some other way or not use 5 Suffix rules for archive files You can write a special kind of suffix rule for dealing with archive files See Section 10 7 Old fashioned suffix rules on page 129 for a full explanation of suffix rules Archive suffix rules are obsolete in GNU make because pattern rules for archives are a more general mechanism But they are retained for compatibility with other makes To write a suffix rule for archives you simply write a suffix rule using the target suffix a the usual suffix for archive files For example here is the old fashioned suffix rule to update a library archive from C source files C a CC CFLAGS CPPFLAGS lt o o 58 5 0 RM 5 This works just as if you had written the pattern rule 9 Be
120. dscript sed e sedscript foo man gt foo 1 will fail when the build directory is not the source directory because foo man and sedscript are in the source directory When using GNU make relying on vPATH to find the source file will work in the case where there is a single dependency file since the make automatic variable will represent the source file wherever it is Many versions of make set only in implicit rules A Makefile target like fooro i bar c CC IS srcdir CFLAGS c bar c o foo o should instead be written as foo o bar c 5 I I srcdir CFLAGS c lt o 143 185 14 Makefile Conventions ST9 gmake Reference Manual 14 2 144 185 in order to allow VPATH to work correctly When the target has multiple dependencies using an explicit srcdir is the easiest way to make the rule work well For example the target above for foo 1 is best written as foo 1 sedscript sed e srcdir sedscript srcdir foo man gt S GNU distributions usually contain some files which are not source files for example Info files and the output from Autoconf Automake Bison or Flex Since these files normally appear in the source directory they should always appear in the source directory not in the build directory So Makefile rules to update them should put the updated files in the source directory However if a file does not appear in the distribution then the Makefile shou
121. e The names oo FOO and Foo all refer to different variables It is traditional to use upper case letters in variable names but we recommend using lower case letters for variable names that serve internal purposes in the makefile and reserving upper case for parameters that control implicit rules or for parameters that the user should override with command options see Section 9 5 Overriding variables on page 104 A few variables have names that are a single punctuation character or just a few characters These are the automatic variables and they have particular specialized uses See Section 10 5 3 Automatic variables on page 123 Basics of variable references To substitute a variable s value write a dollar sign followed by the name of the variable in parentheses or braces either foo foo is a valid reference to the variable oo This special significance of is why you must write to have the effect of a single dollar sign in a file name or command Variable references can be used in any context targets prerequisites commands most directives and new variable values Here is an example of a common case where a variable holds the names of all the object files in a program 63 185 6 How to Use Variables ST9 gmake Reference Manual 6 2 64 185 objects program o foo o utils o program S objects cc o program objects objects defs h Variable references work by strict textual substitutio
122. e if one prerequisite pattern is then substitution of the stem foo gives the prerequisite name oo c It is legitimate to write a prerequisite pattern that does not contain then this prerequisite is the same for all targets characters in pattern rules can be quoted with preceding backslashes Backslashes that would otherwise quote characters can be quoted with more backslashes Backslashes that quote characters or other backslashes are removed from the pattern before it is compared to file names or has a stem substituted into it Backslashes that not in danger of quoting characters go unmolested For example the pattern the Sweird pattern has the weird preceding the operative character and pattern following it The final two backslashes are left alone because they cannot affect any character Here is an example which compiles each of and bar o from the corresponding c file objects foo o bar o all objects objects 0 c CC 5 5 o Here is the automatic variable that holds the name of the prerequisite and 6 is the automatic variable that holds the name of the target see Section 10 5 3 Automatic variables on page 123 Each target specified must match the target pattern a warning is issued for each target that does not If you have a list of files only some of which will match the pattern you can use the ilter function to remove non match
123. e Conventions 14 5 4 Standard targets for users All GNU programs should have the following targets in their Makefiles all install Compile the entire program This should be the default target This target need not rebuild any documentation files Info files should normally be included in the distribution and DVI files should be made only when explicitly asked for By default the Make rules should compile and link with so that executable programs have debugging symbols Users who don t mind being helpless can strip the executables later if they wish Compile the program and copy the executables libraries and so on to the file names where they should reside for actual use If there is a simple test to verify that a program is properly installed this target should run that test Do not strip executables when installing them Devil may care users can use the install strip target to do that If possible write the install target rule so that it does not modify anything in the directory where the program was built provided make 11 has just been done This is convenient for building the program under one user name and installing it under another The commands should create all the directories in which files are to be installed if they don t already exist This includes the directories specified as the values of the variables prefix and exec prefix as well as all subdirectories that are needed One way to do this
124. e stem src a with a prerequisite pattern c x gives the file name src car Match anything pattern rules When a pattern rule s target is just it matches any file name whatever We call these rules match anything rules They are very useful but it can take a lot of time for make to think about them because it must consider every such rule for each file name listed either as a target or as a prerequisite Suppose the makefile mentions oo c For this target make would have to consider making it by linking an object file or by compilation and linking one step from foo c c or by Pascal compilation and linking from foo c p and many other possibilities We know these possibilities are ridiculous since oo c is a C source file not an executable If make did consider these possibilities it would ultimately reject them because files such as and foo c p would not exist But these possibilities are so numerous that make would run very slowly if it had to consider them To gain speed we have put various constraints on the way make considers match anything rules There are two different constraints that can be applied and each time you define a match anything rule you must choose one or the other for that rule ky 5 9 gmake Reference Manual 10 Implicit Rules 3 One choice is to mark the match anything rule as terminal by defining it with a double colon When a rule is terminal it does
125. e you add a macro or a declaration to a header file that many other files depend on Being conservative make assumes that any change in the header file requires recompilation of all dependent files but you know that they do not need to be recompiled and you would rather not waste the time waiting for them to compile If you anticipate the problem before changing the header you can use the t flag This flag tells make not to run the commands in the rules but rather to mark the target up to date by changing its last modification date You would follow this procedure 1 Use the command make to recompile the source files that really need recompilation 2 Make the changes in the header files 3 Use the command make t to mark all the object files as up to date The next time you run make the changes in the header files will not cause any recompilation If you have already changed the header file at a time when some files do need recompilation it is too late to do this Instead you can use the o FILE flag which 103 185 9 How to Run Make ST9 gmake Reference Manual 9 5 104 185 marks a specified file as old see Section 9 7 Summary of options on page 106 for more information This means that the file itself will not be remade and nothing else will be remade on its account Follow this procedure 1 Recompile the source files that need compilation for reasons independent of the particular header file with ma
126. ection 8 2 Functions for string substitution and analysis on page 86 We provide substitution references as well as patsubst for compatibility with other implementations of make Another type of substitution reference lets you use the full power of the pat subst function It has the same form VAR A B described above except that now A must contain a single character This case is equivalent to 5 patsubst A B VAR See Section 8 2 Functions for string substitution and analysis page 86 for a description of the pat subst function foo b o bar f00 0 c sets bartOa c b c c c Computed variable names Computed variable names are a complicated concept needed only for sophisticated makefile programming For most purposes you need no consider them except to know that making a variable with a dollar sign in its name might have strange results However if you are the type that wants to understand everything or you are actually interested in what they do read on Variables may be referenced inside the name of a variable This is called a computed variable name or a nested variable reference 67 185 6 How to Use Variables ST9 gmake Reference Manual 68 185 For example y 5 defines a as z the x inside expands to so 5 expands to 5 y which in turn expands z Here the of the variable t
127. ed so they appear as they do in the makefile except for the stripping of initial whitespace 137 185 12 Features of GNU Make ST9 gmake Reference Manual 138 185 The following features were inspired by various other versions of make In some cases it is unclear exactly which versions inspired which others Pattern rules using This has been implemented in several versions of make We re not sure who invented it first but it s been spread around a bit See Section 10 5 Defining and redefining pattern rules on page 121 for more information Rule chaining and implicit intermediate files This was implemented by Stu Feldman in his version of make for AT amp T Eighth Edition Research Unix and later by Andrew Hume of AT amp T Bell Labs in his mk program where he terms it transitive closure We do not really know if we got this from either of them or thought it up ourselves at the same time See Section 10 4 Chains of implicit rules on page 119 for more information The automatic variable containing a list of all prerequisites of the current target We did not invent this but we have no idea who did See Section 10 5 3 Automatic variables on page 123 The automatic variable is a simple extension of 57 The what flag w in GNU make was as far as we know invented by Andrew Hume in mk See Section 9 3 Instead of executing the commands on page 102 The concept of doing several things at once parallelism
128. ed by a floating point number For example 1 2 5 will not let make start more than one job if the load average is above 2 5 The 1 option with no following number removes the load limit if one was given with a previous 1 option 4 5 9 gmake Reference Manual 5 Writing Commands in Rules 5 4 4 More precisely when make goes to start up a job it already has at least one job running it checks the current load average if it is not lower than the limit given with 1 make waits until the load average goes below that limit or until all the other jobs finish By default there is no load limit Errors in commands After each shell command returns make looks at its exit status If the command completed successfully the next command line is executed in a new shell after the last command line is finished the rule is finished If there is an error the exit status is nonzero make gives up on the current rule and perhaps on all rules Sometimes the failure of a certain command does not indicate a problem For example you may use the mkdir command to ensure that a directory exists If the directory already exists mkdir will report an error but you probably want make to continue regardless To ignore errors in a command line write a at the beginning of the line s text after the initial tab The is discarded before the command is passed to the shell for execution For example clean Wm 4209 This
129. efile does not exist but can be created by running make rules you probably want the rules to be run so that the makefile can be used Therefore if none of the default makefiles exists make will try to make each of them in the same order in which they are searched for see Section 3 2 What name to give your makefile on page 20 until it succeeds in making one or it runs out of names to try It is not an error if make cannot find or make any makefile a makefile is not always necessary When you use the t or touch option see Section 9 3 Instead of executing the commands on page 102 you would not want to use an out of date makefile to decide which targets to touch So the t option has no effect on updating makefiles they are really updated even if t is specified Likewise q or question and n or just print do not prevent updating of makefiles because an out of date makefile would result in the wrong output for other targets Thus make f mfile n foo Will update mfile read it in and then print the commands to update foo and its prerequisites without running them The 23 185 3 Writing Makefiles ST9 gmake Reference Manual 3 6 24 185 commands printed for oo will be those specified in the updated contents of mfile However on occasion you might actually wish to prevent updating of even the makefiles You can do this by specifying the makefiles as goals in the command line as well as specifying them a
130. eplace words matching PATTERN with REPLACEMENT in TEXT See Section 8 2 Functions for string substitu tion and analysis on page 86 strip STRING Remove excess whitespace characters from sTRING See Section 8 2 Functions for string substitution and analysis on page 86 findstring FIND TEXT Locate FIND in TEXT See Section 8 2 Functions for string substitution and analysis on page 86 filter PATTI Select words in TEXT that match one of the PATTERN words See Section 8 2 Functions for string substitu tion and analysis on page 86 filter out PATTI Select words in TEXT that not match any of the PAT TERN words See Section 8 2 Functions for string substitution and analysis on page 86 sort LIST Sort the words in LIST lexicographically removing dupli cates See Section 8 2 Functions for string substitu tion and analysis on page 86 dir NAMES Extract the directory part of each file name See Section 8 3 Functions for file names on page 89 notdir NAMES Extract the non directory part of each file name See Sec tion 8 3 Functions for file names on page 89 suffix NAMES Extract the suffix the last and following characters of each file name See Section 8 3 Functions for file names on page 89 basename NAMES Extract the base name name without suffix of each file name See Section 8 3 Functions
131. erence Manual 7 Conditional Parts of Makefiles 7 CONDITIONAL PARTS OF MAKEFILES A conditional causes part of a makefile to be obeyed or ignored depending on the values of variables Conditionals can compare the value of one variable to another or the value of a variable to a constant string Conditionals control what make actually sees in the makefile so they cannot be used to control shell commands at the time of execution 7 1 Example of a conditional The following example of a conditional tells make to use one set of libraries if the CC variable is gcc and a different set of libraries otherwise It works by controlling which of two command lines will be used as the command for a rule The result is that as an argument to make changes not only which compiler is used but also which libraries are linked 1 for gcc lgnu normal libs foo 5 objects ifeq CC gcc 5 o foo objects libs for else 5 o foo objects normal libs endif This conditional uses three directives one ifeq one else and one endi f The ifeq directive begins the conditional and specifies the condition It contains two arguments separated by a comma and surrounded by parentheses Variable substitution is performed on both arguments and then they are compared The lines of the makefile following the ifeq are obeyed if the two arguments match otherwise they are ignored The eise directive c
132. es for uninstall 5 UNINSTALL Pre uninstall commands follow POST UNINSTALL Post uninstall commands follow NORMAL UNINSTALL Normal commands follow Typically a pre uninstall command would be used for deleting entries from the Info directory If the install Or uninstall target has any dependencies which act as subroutines of installation then you should start each dependency s commands with a category line and start the main target s commands with a category line also This way you can ensure that each command is placed in the right category regardless of which of the dependencies actually run Pre installation and post installation commands should not run any programs except for these basename bash cat chgrp chmod chown cmp cp dd diff echo egrep expand expr false fgrep find getopt grep gunzip gzip hostname install install info kill ldconfig ln 15 md5sum 4 ST9 gmake Reference Manual 14 Makefile Conventions 4 mkdir mkfifo mknod mv printenv pwd rm rmdir sed sort tee test touch true uname xargs yes The reason for distinguishing the commands in this way is for the sake of making binary packages Typically a binary package contains all the executables and other files that need to be installed and has its own method of installing them so it does not need to run the normal installation commands But installing the binary package does need to execute the pre installation and post installatio
133. exists in many incarnations of make and similar programs though not in the System V or BSD implementations See Section 5 2 Command execution on page 50 Modified variable references using pattern substitution come from SunOS 4 See Section 6 1 Basics of variable references on page 63 This functionality was provided in GNU make by the patsubst function before the alternate syntax was implemented for compatibility with SunOS 4 It is not altogether clear who inspired whom since GNU make had patsubst before SunOS 4 was released The special significance of characters preceding command lines see Section 9 3 Instead of executing the commands on page 102 is mandated by IEEE Standard 1003 2 1992 POSIX 2 The syntax to append to the value of a variable comes from SunOS 4 make See Section 6 6 Appending more text to variables on page 71 The syntax ARCHIVE 1 MEM2 to list multiple members a single archive file comes from SunOS 4 make See Section 11 1 Archive members as targets on page 133 r ST9 gmake Reference Manual 12 Features of GNU Make 3 The include directive to include makefiles with no error for nonexistent file comes from SunOS 4 make But note that SunOS 4 make does not allow multiple makefiles to be specified in one include directive The same feature appears with the name sinclude SGI make and perhaps others The remaining features are inventions new in GNU make
134. f this function is a string telling you how the variable VARIABLE was defined undefined If VARIABLE Was never defined default If VARIABLE has a default definition as is usual with cc and so on See Section 10 3 Variables used by implicit rules on page 117 If you have redefined a default variable the origin function will return the origin of the later definition environment If VARIABLE was defined as an environment variable and the e option is not turned on see Section 9 7 Summary of options on page 106 for more information environment override If VARIABLE was defined as an environment variable and the option is turned on see Section 9 7 Summary of options on page 106 for more information 95 185 8 Functions to Transform Text ST9 gmake Reference Manual file If VARIABLE was defined in a makefile an command line If VARIABLE was defined on the command line override If VARIABLE was defined with an override directive in a makefile see Section 6 7 The override directive on page 73 automatic If VARIABLE is an automatic variable defined for the execution of the commands for each rule see Section 10 5 3 Automatic variables on page 123 This information is primarily useful other than for your curiosity to determine if you want to believe the value of a variable For example suppose you have a makefile
135. features see Chapter 5 Writing Commands in Rules on page 49 Using wildcard characters in file names A single file name can specify many files using wildcard characters The wildcard characters in make are and the same as in the Bourne shell For example c specifies a list of all the files in the working directory whose names end c SZA 5 9 gmake Reference Manual 4 Writing Rules 4 3 1 4 The character at the beginning of a name also has special significance If alone or followed by a slash it represents your home directory For example bin expands to home you bin If the is followed by a word the string represents the home directory of the user named by that word For example john bin expands to home john bin On systems which don t have a home directory for each user such as MS DOS or MS Windows this functionality can be simulated by setting the environment variable HOME Wildcard expansion happens automatically in targets in prerequisites and in commands where the shell does the expansion In other contexts wildcard expansion happens only if you request it explicitly with the wildcard function The special significance of a wildcard character can be turned off by preceding it with a backslash Thus foo bar would refer to a specific file whose name consists of oo an asterisk and bar Wildcard examples Wildcards can be used in the commands of a rule where they
136. ffect is to append the text Isrc I headers to the previously given value of cFLAGS The override directive is used so that the new value is assigned even if the previous value of CFLAGS was specified with a command argument see Section 6 7 The override directive on page 73 Functions for file names Several of the built in expansion functions relate specifically to taking apart file names or lists of file names Each of the following functions performs a specific transformation on a file name The argument of the function is regarded as a series of file names separated by whitespace leading and trailing whitespace is ignored Each file name in the series is transformed in the same way and the results are concatenated with single spaces between them dir NAMES Extracts the directory part of each file name in NAMES The directory part of the file name is everything up through and including the last slash in it If the file name contains no slash the directory part is the string For example dir src foo c hacks produces the result src notdir NAMES Extracts all but the directory part of each file name in NAMES If the file name contains no slash it is left unchanged Otherwise everything through the last slash is removed from it A file name that ends with a slash becomes an empty string This is unfortunate because it means that the result does not always have the same number of 89 185 8
137. fined implicit rule suffix also counts as a special target if it appears as a target and so does the concatenation of two suffixes such as c o These targets are suffix rules an obsolete way of defining implicit rules but a way still widely used In principle any target name could be special in this way if you break it in two and add both pieces to the suffix list In practice suffixes normally begin with so these special target names also begin with See Section 10 7 Old fashioned suffix rules on page 129 Multiple targets in a rule A rule with multiple targets is equivalent to writing many rules each with one target and all identical aside from that The same commands apply to all the targets but their effects may vary because you can substitute the actual target name into the command using 58 The rule contributes the same prerequisites to all the targets also 41 185 4 Writing Rules ST9 gmake Reference Manual 4 10 42 185 This is useful in two cases e You want just prerequisites no commands For example kbd o command o files o command h gives an additional prerequisite to each of the three object files mentioned Similar commands work for all the targets The commands do not need to be absolutely identical since the automatic variable 8 can be used to substitute the particular target to be remade into the commands see Section 10 5 3 Automatic variables on page 123 For example bigoutput little
138. g cas the argument to either the sort or the strip function This restriction could be removed in the future if that change is shown to be a good idea You can also use computed variable names in the left hand side of a variable assignment or in a define directive as in dir foo dir sources 1 dir c define dir print lpr S dir sources endef This example defines the variables dir foo sources and foo print Nested variable references are quite different from recursively expanded variables see Section 6 2 The two flavors of variables on page 64 though both are used together in complex ways when doing makefile programming How variables get their values Variables can get values in several different ways You can specify an overriding value when you run make See Section 9 5 Overriding variables on page 104 You can specify a value in the makefile either with an assignment see Section 6 5 Setting variables on page 70 or with a verbatim definition see Section 6 8 Defining variables verbatim on page 74 Variables in the environment become make variables See Section 6 9 Variables from the environment on page 74 Several automatic variables are given new values for each rule Each of these has a single conventional use See Section 10 5 3 Automatic variables on page 123 e Several variables have constant initial values See Section 10 3 Variables used by implicit r
139. g directories for prerequisites For large systems it is often desirable to put sources in a separate directory from the binaries The directory search features of make facilitate this by searching several directories automatically to find a prerequisite When you redistribute the files among directories you do not need to change the individual rules just the search paths VPATH search path for all prerequisites The value of the make variable vPATH specifies a list of directories that make should search Most often the directories are expected to contain prerequisite files that are not in the current directory however VPATH specifies a search list that make applies for all files including files which are targets of rules Thus if a file that is listed as a target or prerequisite does not exist in the current directory make searches the directories listed in vPATH for a file with that name If a file is found in one of them that file may become the prerequisite see below Rules may then specify the names of files in the prerequisite list as if they all existed in the current directory See Section 4 4 4 Writing shell commands with directory search on page 34 for more information In the VPATH variable directory names are separated by colons or blanks The order in which directories are listed is the order followed by make in its search On 31 185 4 Writing Rules ST9 gmake Reference Manual 4 4 2 32 185 MS DOS and MS
140. ge 20 Allowing multiple files to be included with a single directive is a GNU extension Variables are read from and communicated via the environment See Section 6 9 Variables from the environment on page 74 Options passed through the variable MAKEFLAGS to recursive invocations of make See Section 5 6 3 Communicating options to a sub make on page 58 The automatic variable 2 is set to the member name in an archive reference See Section 10 5 3 Automatic variables on page 123 The automatic variables 8 5 lt and have corresponding forms like F 5 We have generalized this to as an obvious extension See Section 10 5 3 Automatic variables on page 123 Substitution variable references See Section 6 1 Basics of variable references on page 63 command line options b and m accepted and ignored In System V make these options actually do something Execution of recursive commands to run make via the variable MAKE even if n q or t is specified See Section 5 6 Recursive use of make on page 55 Support for suffix a in suffix rules This feature is obsolete in GNU make because the general feature of rule chaining see Section 10 4 Chains of implicit rules on page 119 for more information allows one pattern rule for installing members in an archive to be sufficient The arrangement of lines and backslash newline combinations in commands is retained when the commands are print
141. gets to be built on the command line and make couldn t find any makefiles to read in The latter means that some makefile was found but it didn t contain any default target and none was given on the command line GNU make has nothing to do in these situations See Section 9 1 Arguments to specify the makefile on page 99 Makefile was not found Included makefile was not found A makefile specified on the command line first form or included second form was not found warning overriding commands for target XXX warning ignoring old commands for target XXX GNU make allows commands to be specified only once per target except for double colon rules If you give commands for a target which already has been defined to have commands this warning is issued and the second set of SZA ST9 gmake Reference Manual Appendix B Errors Generated by Make B 8 B 9 B 10 B 12 B 13 4 commands will overwrite the first set See Section 4 10 Multiple rules for one target on page 42 Circular XXX YYY dependency dropped This means that make detected a loop in the dependency graph after tracing the prerequisite YYY of target XXX and its prerequisites etc one of them depended on XXX again Recursive variable XXX references itself eventually Stop This means you ve defined a normal recursive make variable XXX that when it s expanded will refer to itself XXX This is not all
142. gram or programs they describe If the first rule in the makefile has several targets only the first target in the rule becomes the default goal not the whole list 99 185 9 How to Run Make ST9 gmake Reference Manual Note 100 185 You can specify a different goal or goals with arguments to make Use the name of the goal as an argument If you specify several goals make processes each of them in turn in the order you name them Any target the makefile may be specified as a goal unless it starts with or contains an in which case it will be parsed as a switch or variable definition respectively Even targets not in the makefile may be specified if make can find implicit rules that say how to make them Make will set the special variable MAKECMDGOALS to the list of goals you specified on the command line If no goals were given on the command line this variable is empty This variable should be used only in special circumstances An example of appropriate use is to avoid including d files during clean rules see Section 4 13 Generating prerequisites automatically on page 46 so make won t create them only to immediately remove them again sources foo c bar c ifneq 5 MAKECMDGOALS clean include sources c d endif One use of specifying a goal is if you want to compile only a part of the program or only one of several programs Specify as a goal each file that you wish to remake For e
143. h will come from the terminal or wherever you redirect the standard input of make The first command run will always get it first and the first command started after that one finishes will get it next and so on We will change how this aspect of make works if we find a better alternative In the mean time you should not rely on any command using standard input at all if you are using the parallel execution feature but if you are not using this feature then standard input works normally in all commands Finally handling recursive make invocations raises issues For more information on this see Section 5 6 3 Communicating options to a sub make on page 58 If a command fails is killed by a signal or exits with a nonzero status and errors are not ignored for that command see Section 5 4 Errors in commands on page 53 the remaining command lines to remake the same target will not be run If a command fails and the k keep going option was not given see Section 9 7 Summary of options on page 106 for more information make aborts execution If make terminates for any reason including a signal with child processes running it waits for them to finish before actually exiting When the system is heavily loaded you will probably want to run fewer jobs than when it is lightly loaded You can use the 1 option to tell make to limit the number of jobs to run at once based on the load average The 1 or max 1oad option is follow
144. he automatic variables and lt to substitute the names of the target file and the source file in each case where the rule applies see Section 10 5 3 Automatic variables on page 123 Here is a second built in rule RCS v CO S COFLAGS defines a rule that can make any file x whatsoever from a corresponding file x v in the subdirectory RCS Since the target is this rule will apply to any file whatever provided the appropriate prerequisite file exists The double colon makes the rule terminal which means that its prerequisite may not be an intermediate file see Section 10 5 5 Match anything pattern rules on page 126 This pattern rule has two targets tab c tab h y bison d This tells make that the command bison a X y will make both X tab c and X tab h If the file foo depends on the files parse tab o and scan o and the r 5 9 gmake Reference Manual 10 Implicit Rules 10 5 3 3 scan o depends on the parse tab h when parse y is changed the command bison d parse y Will be executed only once and the prerequisites of both parse tab o and scan o will be satisfied Presumably the file parse tab o Will be recompiled from parse tab c and the file scan o from scan c While is linked from parse tab o scan o and its other prerequisites and it will execute happily ever after Automatic variables Suppose you are writing a pattern rule to compile a c file into a o file ho
145. he variable VARIABLE NAME has an empty value the TEXT IF TRUE is effective otherwise the TEXT IF FALSE if any is effective Extra spaces are allowed and ignored at the beginning of the conditional directive line but a tab is not allowed If the line begins with a tab it will be considered a command for a rule Aside from this extra spaces or tabs may be inserted with no effect anywhere except within the directive name or within an argument comment starting with may appear at the end of the line The other two directives that play a part in a conditional are else and endi Each of these directives is written as one word with no arguments Extra spaces are allowed and ignored at the beginning of the line and spaces or tabs at the end A comment starting with 4 may appear at the end of the line Conditionals affect which lines of the makefile make uses If the condition is true make reads the lines of the TEXT IF TRUE as part of the makefile if the condition is false make ignores those lines completely It follows that syntactic units of the makefile such as rules may safely be split across the beginning or the end of the conditional make evaluates conditionals when it reads a makefile Consequently you cannot use automatic variables in the tests of conditionals because they are not defined until commands are run see Section 10 5 3 Automatic variables on page 123 T
146. hen 5 is set to since c isa suffix GNU make does this bizarre thing only for compatibility with other implementations of make You should generally avoid using except in implicit rules or static pattern rules If the target name in an explicit rule does not end with a recognized suffix is set to the empty string for that rule is useful even in explicit rules when you wish to operate on only the prerequisites that have changed For example suppose that an archive named lib is supposed to contain copies of several object files This rule copies just the changed object files into the archive lib foo o bar o lose o win o ar r lib Of the variables listed above four have values that are single file names and three have values that are lists of file names These seven have variants that get just the file s directory name or just the file name within the directory The variant variables names are formed by appending D or respectively These variants are semi obsolete in GNU make since the functions dir and notdir can be used to get a r 5 9 gmake Reference Manual 10 Implicit Rules Note 4 similar effect see Section 8 3 Functions for file names on page 89 Note however that the F variants all omit the trailing slash which always appears in the output of the di x function Here is a list of the variants 8D The directory part of the file name of the target with the trailing slash re
147. ile the same special version will be executed for recursive invocations As a special feature using the variable MAKE in the commands of a rule alters the effects of the t touch n just print or q question option Using the MAKE variable has the same effect as using a character at the 55 185 5 Writing Commands in Rules ST9 gmake Reference Manual 5 6 2 56 185 beginning of the command line See Section 9 3 Instead of executing the commands on page 102 Consider the command make t in the above example The t option marks targets as up to date without actually running any commands Following the usual definition of t a make t command in the example would create a file named subsystem and do nothing else What you really want it to do is run subdir amp amp make t but that would require executing the command and t says not to execute commands The special feature makes this do what you want whenever a command line of a rule contains the variable MAKE the flags t n and q do not apply to that line Command lines containing MAKE are executed normally despite the presence of a flag that causes most commands not to be run The usual MAKEFLAGS mechanism passes the flags to the sub make see Section 5 6 3 Communicating options to a sub make on page 58 so your request to touch the files or print the commands is propagated to the subsystem Communicating variables to a sub make
148. ing whitespace as a non empty value For example ifeq S strip foo TEXT IF EMPTY endif will evaluate TEXT IF EMPTY even if the expansion of foo contains whitespace characters ifneq ARG1 ARG2 1 ARG2 ARGL ARG2 1 ARG2 ARG1 ARG2 Expand all variable references in ARG1 and ARG2 and compare them If they are different the TEXT IF TRUE is effective otherwise the TEXT IF FALSE if any is effective ifdef VARIABLE NAME If the variable VARIABLE NAME has a non empty value the TEXT IF TRUE is effective otherwise the TEXT IF FALSE if any is effective Variables that have never been defined have an empty value Note that ifdef only tests whether a variable has a value It does not expand the variable to ensure that the value is not empty Consequently tests using ifdef return true for all definitions except those like oo To test for an empty value use ifeq foo For example bar foo 5 bar ifdef foo frobozz else frobozz no endif yes sets frobozz to yes while foo ifdef foo frobozz yes else 4 81 185 7 Conditional Parts of Makefiles ST9 gmake Reference Manual 7 3 82 185 frobozz no endif sets frobozz to no ifndef VARIABLE NAME If t
149. ing any infinite loop in the search for an implicit rule chain There are some special implicit rules to optimize certain cases that would otherwise be handled by rule chains For example making foo from foo c could be handled by compiling and linking with separate chained rules using oo o as an intermediate file But what actually happens is that a special rule for this case does the compilation and linking with a single cc command The optimized rule is used in preference to the step by step chain because it comes earlier in the ordering of rules r 5 9 gmake Reference Manual 10 Implicit Rules 10 5 Note 10 5 1 3 Defining redefining pattern rules You define an implicit rule by writing a pattern rule A pattern rule looks like an ordinary rule except that its target contains the character exactly one of them The target is considered a pattern for matching file names the can match non empty substring while other characters match only themselves The prerequisites likewise use to show how their names relate to the target name Thus a pattern rule c says how to make any STEM from another file STEM Expansion using in pattern rules occurs after any variable or function expansions which take place when the makefile is read See Chapter 6 How to Use Variables on page 63 and Section 8 Functions to Transform Text on page 85 Introduction to pattern rules A p
150. ing file names see Section 8 2 Functions for string substitution and analysis on page 86 files foo elc bar o lose o filter 0 files 0 c CC c S CFLAGS lt o filter elc files elc 1 4 44 185 5 9 gmake Reference Manual 4 Writing Rules 4 11 2 4 12 3 emacs f batch byte compile In this example the result of filter 0 files lose o and the first static pattern rule causes each of these object files to be updated by compiling the corresponding C source file The result of filter elc files is foo elc so that file is made from 1 Another example shows how to use in static pattern rules bigoutput littleoutput output text g generate text g Q When the generate command is run will expand to the stem either big or little Static pattern rules versus implicit rules A static pattern rule has much in common with an implicit rule defined as a pattern rule see Section 10 5 Defining and redefining pattern rules on page 121 Both have a pattern for the target and patterns for constructing the names of prerequisites The difference is in how make decides when the rule applies An implicit rule apply to any target that matches its pattern but it does apply only when the target has no commands otherwise specified and only when the prerequisites can be found If more than one implicit rule appears appli
151. ion set 9 Aboutthis manuak onani 10 Hcr Dm 10 Introduction to Makefiles 11 Whata rule ue EE Ludere 11 A simple makefile uuo etate nang 12 How make processes a Makefile 13 Variables make makefiles simpler n 14 Letting make deduce the 15 Another Style Of makefile ect et rtr ce etate 16 Rules for cleaning the directory 17 Writing Makefiles 19 What makefiles contain 19 What name to give your makefile 20 Including other makefiles 0 00 20 The variable MAKEFILES sse enne 22 How makefiles are remade 22 Overriding part of another makefile 2 24 How make reads a Makefile 25 Writing AUTE RERUMS ER TY YA 27 Rule example 27 UE de 27 Using wildcard characters
152. irective together with define override define two lines foo 5 bar endef See Section 6 7 The override directive on page 73 Variables from the environment Variables in make can come from the environment in which make is run Every environment variable that make sees when it starts up is transformed into a make variable with the same name and value But an explicit assignment in the makefile SZA ST9 gmake Reference Manual 6 How to Use Variables 6 10 3 or with a command argument overrides the environment If the flag is specified then values from the environment override assignments in the makefile See Section 9 7 Summary of options on page 106 for more information But this is not recommended practice Thus by setting the variable CFLAGS in your environment you can cause all C compilations in most makefiles to use the compiler switches you prefer This is safe for variables with standard or conventional meanings because you know that no makefile will use them for other things But this is not totally reliable some makefiles set CFLAGS explicitly and therefore are not affected by the value in the environment When make is invoked recursively variables defined in the outer invocation can be passed to inner invocations through the environment see Section 5 6 Recursive use of make on page 55 By default only variables that came from the environment or the command line are passed to recursive invocatio
153. is Hello 4 ST9 gmake Reference Manual 6 How to Use Variables 3 A computed variable name need not consist entirely of a single variable reference It can contain several variable references as well as some invariant text For example a dirs dira dirb 1 dirs dirl dir2 a files filea fileb 1 files filel fi 2 ifeq S S use a yes al a else al 1 endif ifeq S use_dirs yes df dirs else df files endif dirs 6 5 1 df will give dirs the same value as dirs 1 dirs files Or 1 files depending on the settings of use a and use dirs Computed variable names can also be used in substitution references a objects b o 1 objects 1 0 2 0 340 sources al objects o c defines sources as either a c b c 1 2 c 3 c depending on the value of a1 The only restriction on this sort of use of nested variable references is that they cannot specify part of the name of a function to be called This is because the test for a recognized function name is done before the expansion of nested references For example ifdef do sort func sort else func strip endif func 69 185 6 How to Use Variables ST9 gmake Reference Manual Note 6 4 6 5 70 185 attempts to give foo the value of the variable sort a d b g q corstrip a d g q c rather than giving a d b
154. is by means of an installdirs target as described below Use before any command for installing a man page so that make will ignore any errors This is in case there are systems that don t have the Unix man page documentation system installed The way to install Info files is to copy them into infodir with INSTALL DATA andthen run the install info program if it is present install info is a program that edits the Info air file to add or update the menu entry for the given Info file it is part of the Texinfo package Here is a sample rule to install an Info file DESTDIR infodir foo info foo info POST_INSTALL There may be a newer info file in than in srcdir if test f foo info then d else d srcdir fi S INSTALL DATA d foo info DESTDIR 153 185 14 Makefile Conventions ST9 gmake Reference Manual Run install info only if it exists Use if instead of just prepending to the line so we notice real errors from install info We use S SHELL c because some shells do not fail gracefully when there is an unknown command if S SHELL c install info version gt dev null 2 gt amp 1 then install info dir file DESTDIR infodir dir 5 DESTDIR infodir foo info else true fi When writing the install target you must classify all the commands into three categories normal ones pre installation commands and post installation commands See Se
155. is when you want to generate prerequisites from source files automatically the prerequisites can be put in a file that is included by the main makefile This practice is generally cleaner than that of somehow appending the prerequisites to the end of the main makefile as has been traditionally done with other versions of make See Section 4 13 Generating prerequisites automatically on page 46 If the specified name does not start with a slash and the file is not found in the current directory several other directories are searched First any directories you have specified with the I or include dir option are searched see Section 9 7 Summary of options on page 106 for more information Then the following directories if they exist are searched in this order PREFIX include normally usr local include usr gnu include usr local include usr include If an included makefile cannot be found in any of these directories a warning message is generated but it is not an immediately fatal error processing of the makefile containing the include continues Once it has finished reading makefiles make will try to remake any that are out of date or don t exist See Section 3 5 How makefiles are remade on page 22 Only after it has tried to find a way to remake a makefile and failed will make diagnose the missing makefile as a GNU Make compiled for MS DOS and MS Windows behaves as if PREFIX has been defined to be the root of the
156. ites for IGNORE then make will ignore errors in execution of the commands run for those particular files The commands for IGNORE are not meaningful If mentioned as a target with no prerequisites IGNORE says to ignore errors in execution of commands for all files This usage of IGNORE is supported only for historical compatibility Since this affects every command in the makefile it is not very useful we recommend you use the more selective ways to ignore errors in specific commands See Section 5 4 Errors in commands on page 53 SILENT If you specify prerequisites for SILENT then make will not print the commands to remake those particular files before executing them The commands for STLENT are not meaningful If mentioned as a target with no prerequisites SILENT says not to print any commands before executing them This usage of SILENT is supported only for historical compatibility We recommend you use the more selective ways to silence specific commands See Section 5 1 Command echoing on page 49 If you want to silence all commands for a particular run of make use the s or silent option see Section 9 7 Summary of options on page 106 EXPORT ALL VARIABLES Simply by being mentioned as a target this tells make to export all variables to child processes by default See Section 5 6 2 Communicating variables to a sub make on page 56 Any de
157. ity in that it will check out SCCS files for makefiles Various new built in implicit rules See Section 10 2 Catalog of implicit rules on page 113 for more information The built in variable MAKE VERSION gives the version number of make 4 ST9 gmake Reference Manual 13 3 13 Incompatibilities amp Missing Features INCOMPATIBILITIES amp MISSING FEATURES The make programs in various other systems support a few features that are not implemented in GNU make The POSIX 2 standard IEEE Standard 1003 2 1992 which specifies make does not require any of these features A target of the form FILE ENTRY stands for a member of archive file FILE The member is chosen not by name but by being an object file which defines the linker symbol ENTRY This feature was not put into GNU make because of the non modularity of putting knowledge into make of the internal format of archive file symbol tables See Section 11 2 1 Updating archive symbol directories on page 134 Suffixes used in suffix rules that end with the character have a special meaning to System V make they refer to the SCCS file that corresponds to the file one would get without the For example the suffix rule c o would make the file N o from the SCCS file s N c For complete coverage a whole series of such suffix rules is required See Section 10 7 Old fashioned suffix rules on page 129 In GNU make this entire series of ca
158. k of formatting TeX is not distributed with Texinfo dist Create a distribution tar file for this program The tar file should be set up so that the file names in the tar file start with a subdirectory name which is the name of the package it is a distribution for This name can include the version number For example the distribution tar file of GCC version 1 40 unpacks into a subdirectory named gcc 1 40 The easiest way to do this is to create a subdirectory appropriately named use 1n or cp to install the proper files in it and then tar that subdirectory Compress the tar file with gzip For example the actual distribution file for GCC version 1 40 is called gcc 1 40 tar gz The dist target should explicitly depend on all non source files that are in the distribution to make sure they are up to date in the distribution 4 156 185 ST9 gmake Reference Manual 14 Makefile Conventions 14 6 4 check Perform self tests if any The user must build the program before running the tests but need not install the program you should write the self tests so that they work when the program is built but not installed The following targets are suggested as conventional names for programs in which they are useful installcheck Perform installation tests if The user must build and install the program before running the tests You should not assume that bindir isin the search path installdirs It s usefu
159. ke distclean should leave only the files that were in the distribution 154 185 ST9 gmake Reference Manual 14 Makefile Conventions 4 mostlyclean maintainer clean TAGS Like clean but may refrain from deleting a few files that people normally don t want to recompile For example the mostlyclean target for GCC does not delete 1ibgcc a because recompiling it is rarely necessary and takes a lot of time Delete almost everything from the current directory that can be reconstructed with this Makefile This typically includes everything deleted by distclean plus more C source files produced by Bison tags tables Info files and so on The reason we say almost everything is that running the command make maintainer clean should not delete configure even if configure can be remade using a rule in the Makefile More generally make maintainer clean should not delete anything that needs to exist in order to run configure and then begin to build the program This is the only exception maintainer clean should delete everything else that can be rebuilt The maintainer clean target is intended to be used by a maintainer of the package not by ordinary users You may need special tools to reconstruct some of the files that make maintainer clean deletes Since these files are normally included in the distribution we don t take care to make them easy to reconstruct If you find you need to unpack the full distribution
160. ke o HEADERFILE If several header files are involved use a separate o option for each header file 2 Touch all the object files with make t Overriding variables An argument that contains specifies the value of a variable v x sets the value of the variable v to x If you specify a value in this way all ordinary assignments of the same variable in the makefile are ignored we say they have been overridden by the command line argument The most common way to use this facility is to pass extra flags to compilers For example a properly written makefile the variable CFLAGS is included in each command that runs the C compiler so a file oo c would be compiled something like this cc c 5 5 foo c Thus whatever value you set for CFLAGS affects each compilation that occurs The makefile probably specifies the usual value for CFLAGS like this CFLAGS g Each time you run make you can override this value if you wish For example if you Say make CFLAGS g O each C compilation will be done with cc c O This illustrates how you can use quoting in the shell to enclose spaces and other special characters in the value of a variable when you override it The variable CFLAGS is only one of many standard variables that exist just so that you can change them this way See Section 10 3 Variables used by implicit rules on page 117 for a complete list You can also program the makefile to lo
161. ke clean but may refrain from deleting a few files that people normally don t want to recompile For example the most lyclean target for GCC does not delete 1ibgcc a because recompiling it is rarely nec essary and takes a lot of time Any of these targets might be defined to delete more files than clean does For example this would delete configuration files or links that you would normally cre ate as preparation for compilation even if the makefile itself cannot create these files Copy the executable file into a directory that users typi cally search for commands copy any auxiliary files that the executable uses into the directories where it will look for them Print listings of the source files that have changed Create a tar file of the source files Create a shell archive shar file of the source files Create a distribution file of the source files This might be a tar file or a shar file or a compressed version of one of the above or even more than one of the above Update a tags table for this program Perform self tests on the program this makefile builds 101 185 9 How to Run Make ST9 gmake Reference Manual 9 3 102 185 Instead of executing the commands The makefile tells make how to tell whether a target is up to date and how to update each target But updating the targets is not always what you want Certain options specify other activities for make n The activity is to print
162. kefile data base and the last modification times of the files to decide which of the files need to be updated For each of those files it issues the commands recorded in the data base You can provide command line arguments to make to control which files should be recompiled or how Refer to Section 9 How to Run Make on page 99 for more information How to read this manual If you are new to make or are looking for a general introduction read the first few sections of each chapter skipping the later sections In each chapter the first few sections contain introductory or general information and the later sections contain specialized or technical information The exception is the second chapter Chapter 2 Introduction to Makefiles on page 11 all of which is introductory 7 185 1 Introduction ST9 gmake Reference Manual 1 3 1 4 1 4 1 8 185 If you are familiar with other make programs refer to Chapter 12 Features of GNU Make on page 137 which lists the enhancements GNU make has and Chapter 13 Incompatibilities amp Missing Features on page 141 which explains the few things GNU make lacks that others have For a quick summary see Appendix A Quick Reference on page 161 Section 9 7 Summary of options on page 106 and Section 4 8 Special built in target names on page 39 Problems and bugs If you have problems with GNU make or think you ve found a bug please report it to the developers we cannot promise to do
163. l Pec CFLAGS CPPFLAGS c lt o o 5 r 8 5 5 5 In fact this is just what make does when it sees a suffix rule with a as the target suffix Any double suffix rule x a is converted to a pattern rule with the target pattern and a prerequisite pattern of x Since you might want to use as the suffix for some other kind of file make also converts archive suffix rules to pattern rules in the normal way see Section 10 7 135 185 11 Updating Archive Files ST9 gmake Reference Manual Old fashioned suffix rules on page 129 two pattern rules 5 0 xand Thus a double suffix rule x a produces a 4 136 185 ST9 gmake Reference Manual 12 Features of GNU Make 12 3 FEATURES OF GNU MAKE Here is a summary of the features of GNU make for comparison with and credit to other versions of make We consider the features of make in 4 2 BSD systems as a baseline If you are concerned with portable makefiles you should not use the features of make listed here nor the ones in Missing Many features come from the version of make in System V The vPATH variable and its special meaning See Section 4 4 Searching directories for prerequisites on page 31 This feature exists in System V make but is undocumented It is documented in 4 3 BSD make which says it mimics System V s VPATH feature Included makefiles See Section 3 3 Including other makefiles on pa
164. l than ordinary rules with multiple targets because the targets do not have to have identical prerequisites Their prerequisites must be analogous but not necessarily identical Syntax of static pattern rules Here is the syntax of a static pattern rule TARGETS TARGET PATTERN DEP PATTERNS COMMANDS The TARGETS list specifies the targets that the rule applies to The targets can contain wildcard characters just like the targets of ordinary rules see Section 4 3 Using wildcard characters in file names on page 28 The TARGET PATTERN and DEP PATTERNS say how to compute the prerequisites of each target Each target is matched against the TARGET PATTERN to extract a part of the target name called the stem This stem is 43 185 4 Writing Rules ST9 gmake Reference Manual substituted into each of the DEP PATTERNS to make the prerequisite names one from each DEP PATTERN Each pattern normally contains the character just once When the TARGET PATTERN matches a target the can match any part of the target name this part is called the stem The rest of the pattern must match exactly For example the target matches the pattern with oo as the stem The targets oo c and oo out do not match that pattern The prerequisite names for each target are made by substituting the stem for the in each prerequisite pattern For exampl
165. l to add a target named installdirs to create the directories where files are installed and their parent directories There is a script called mkinstalldirs which is convenient for this you can find it in the Texinfo package You can use a rule like this Make sure all installation directories e g bindir actually exist by making them if necessary installdirs mkinstalldirs srcdir mkinstalldirs bindir 11 5 mandir datadir infodir 5 5 This rule should not modify the directories where compilation is done It should do nothing but create installation directories Install command categories When writing the install target you must classify all the commands into three categories normal ones pre installation commands post installation commands Normal commands move files into their proper places and set their modes They may not alter any files except the ones that come entirely from the package they belong to Pre installation and post installation commands may alter other files in particular they can edit global configuration files or data bases Pre installation commands are typically executed before the normal commands and post installation commands are typically run after the normal commands The most common use for a post installation command is to run install info This cannot be done with a normal command since it alters a file the Info
166. later on when considering how to make the rule for running Yacc is used Ultimately both N c and N o are updated However even if N c does not exist and is not mentioned make knows how to envision it as the missing link between N o and N y In this case N c is called an intermediate file Once make has decided to use the intermediate file it is entered in the data base as if it had been mentioned in the makefile along with the implicit rule that says how to create it Intermediate files are remade using their rules just like all other files But intermediate files are treated differently in two ways 119 185 10 Implicit Rules ST9 gmake Reference Manual 120 185 The first difference is what happens if the intermediate file does not exist If an ordinary file B does not exist and make considers a target that depends on B it invariably creates B and then updates the target from B But if B is an intermediate file then make can leave well enough alone It won t bother updating B or the ultimate target unless some prerequisite of B is newer than that target or there is some other reason to update that target The second difference is that if make does create B in order to update something else it deletes B later on after it is no longer needed Therefore an intermediate file which did not exist before make also does not exist after make make reports the deletion to you by printing a rm f command showing which file i
167. ld not put it in the source directory because building a program in ordinary circumstances should not modify the source directory in any way Try to make the build and installation targets at least and all their subtargets work correctly with a parallel make Utilities in makefiles Write the Makefile commands and any shell scripts such as configure to runin sh notin csh Don t use any special features of ksh or bash The configure script and the Makefile rules for building and installation should not use any utilities directly except these cat cmp cp diff echo egrep expr false grep install info ln ls mkdir mv pwd rm rmdir sed sleep sort tar test touch true The compression program gzip can be used in the dist rule Stick to the generally supported options for these programs For example don t use mkdir convenient as it may be because most systems don t support it It is a good idea to avoid creating symbolic links in makefiles since a few systems don t support them The Makefile rules for building and installation can also use compilers and related programs but should do so via make variables so that the user can substitute alternatives Here are some of the programs we mean ar bison cc flex install ld ldconfig lex make makeinfo ranlib texi2dvi yacc Use the following make variables to run those programs 5 5 CC 5 S INSTALL LD LDCONFIG LEX
168. le SHELL in Makefiles is different on MS DOS The stock shell command com is ridiculously limited in its functionality and many users of make tend to install a replacement shell Therefore on MS DOS make examines the value of SHELL and changes its behavior based on whether it points to a Unix style or DOS style shell This allows reasonable functionality even if SHELL points to command com If SHELL points to a Unix style shell make on MS DOS additionally checks whether that shell can indeed be found if not it ignores the line that sets SHELL In MS DOS GNU make searches for the shell in the following places 1 In the precise place pointed to by the value of SHELL For example if the makefile specifies SHELL bin sh make will look in the directory bin the current drive 2 Inthe current directory each of the directories in the PATH variable in order 4 5 9 gmake Reference Manual 5 Writing Commands in Rules Note 5 3 3 In every directory it examines make will first look for the specific sn in the example above If this is not found it will also look in that directory for that file with one of the known extensions which identify executable files For example exe com bat btm sh and some others If any of these attempts is successful the value of SHELL will be set to the full pathname of the shell as found However if none of these is found the value of S
169. le in MAKEFILES can do useful things to help the built in implicit rules work better such as defining search paths see Section 4 4 3 How directory searches are performed on page 33 for more information Some users are tempted to set MAKEFILES in the environment automatically on login and program makefiles to expect this to be done This is a very bad idea because such makefiles will fail to work if run by anyone else It is much better to write explicit include directives in the makefiles See Section 3 3 Including other makefiles on page 20 How makefiles are remade Sometimes makefiles can be remade from other files such as RCS or SCCS files If a makefile can be remade from other files you probably want make to get an up to date version of the makefile to read in To this end after reading in all makefiles make will consider each as a goal target and attempt to update it If a makefile has a rule which says how to update it found either in that very makefile or in another one or if an implicit rule applies to it see Section 10 1 Using implicit rules on page 111 for more information it will be updated if necessary After all makefiles have been checked if any have actually r 5 9 gmake Reference Manual 3 Writing Makefiles Note 3 been changed make starts with a clean slate and reads all the makefiles over again It will also attempt to update each of them over again but normally
170. le is from a C source file using the C compiler cc Implicit rules tell make how to use customary techniques so that you do not have to specify them in detail when you want to use them For example there is an implicit rule for C compilation File names determine which implicit rules are run For example C compilation typically takes a c file and makes a o file So make applies the implicit rule for C compilation when it sees this combination of file name endings A chain of implicit rules can apply in sequence for example make will remake a o file from a y file by way of a c file The built in implicit rules use several variables in their commands so that by changing the values of the variables you can change the way the implicit rule works For example the variable CF LAGS controls the flags given to the C compiler by the implicit rule for C compilation You can define your own implicit rules by writing pattern rules Suffix rules are a more limited way to define implicit rules Pattern rules are more general and clearer but suffix rules are retained for compatibility Using implicit rules To allow make to find a customary method for updating a target file all you have to do is refrain from specifying commands yourself Either write a rule with no command lines or don t write a rule at all Then make will figure out which implicit rule to use based on which kind of source file exists or can be made For example su
171. lipsis In general terms used to denote the continuation of a series For example in syntax definitions denotes a list of one or more items I In command syntax separates two mutually exclusive alternatives Legal Copyright C 1991 92 93 94 95 96 97 98 99 2000 2001 Free Software Foundation Inc Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one Permission is granted to copy and distribute translations of this manual into another language under the above conditions for modified versions 4 ST9 gmake Reference Manual 2 Introduction to Makefiles 2 1 Note 3 INTRODUCTION MAKEFILES You need a file called makefile to tell make what to do Most often the makefile tells make how to compile and link a program In this chapter we will discuss a simple makefile that describes how to compile and link a text editor which consists of eight C source files and three header files The makefile can also tell make how to run miscellaneous commands when explicitly asked for example to remove certain files as a clean up operation To see a more complex exam
172. ll man pages in more than one section of the manual And finally you should set the following variable srcdix The directory for the sources being compiled The value of this variable is normally inserted by the configure shell script If you are using Autconf use srcdir srcdir For example Common prefix for installation directories NOTE This directory must exist when you start the install prefix usr local xec prefix prefix Where to put the executable for the command gcc bindir exec_prefix bin Where to put the directories used by the compiler libexecdir exec_prefix libexec Where to put the Info files infodir prefix info If your program installs a large number of files into one of the standard user specified directories it might be useful to group them into a subdirectory particular to that program If you do this you should write the instali rule to create these subdirectories Do not expect the user to include the subdirectory name in the value of any of the variables listed above The idea of having a uniform set of variable names for installation directories is to enable the user to specify the exact same values for several different GNU packages order for this to be useful all the packages must be designed so that they will work sensibly when the user does so 4 152 185 ST9 gmake Reference Manual 14 Makefil
173. lles aa teen 24 P Pascal programs omP aa a ae 113 Dobrun cest aee reser t e eade 86 Pattern rules defining ricette ees 121 oxamlple e e ehem 122 match anything eese 126 118 PFLAGS hes 119 Phony 36 DIGTIX ene 147 Prerequisites generating automatically 46 searching directories for 31 print directory 60 xo 137 Ratfor programs 113 preprocessing 114 eis acelin th densi dte 116 Reading 182 185 maketil8S iid eee re RERO 25 Recording 39 Reference to variables advanced features 67 Remakeing makefiles 2 prave re 22 A 119 FU sene 118 Rul definitionis itae etie nz rid 26 iu Re ier 27 Rules double colon 45 27 without commands or prerequisites 38 S deep rc eese 148 SCGCS gt 116
174. ls of recursion sub makes See Section 5 6 Recursive use of make on page 55 The flags given to make You can set this in the environment or a makefile to set flags See Section 5 6 3 Communicating options to a sub make on page 58 ECMDGOALS The targets given to make on the command line Setting this variable has no effect on the operation of make See Section 9 2 Arguments to specify the goals on page 99 CURDIR Set to the pathname of the current working directory after all c options are pro cessed if any Setting this variable has no effect on the operation of make See Section 5 6 Recursive use of make on page 55 SUFFIXE The default list of suffixes before make reads any makefiles LIBPATTERNS Defines the naming of the libraries make searches for and their order See Sec tion 4 4 6 Directory search for link libraries on page 35 4 166 185 ST9 gmake Reference Manual Appendix B Errors Generated by Make APPENDIX B ERRORS GENERATED BY MAKE B 1 B 2 3 This appendix lists most of the common errors you might see generated by make and some information about what they mean and how to fix them Sometimes make errors are not fatal especially in the presence of a prefix on a command script line or the k command line option Errors that are fatal are prefixed with the string Error messages are all either prefixed with the name of the program usually make or if the erro
175. lt 125 185 10 Implicit Rules ST9 gmake Reference Manual 10 5 4 10 5 5 126 185 How patterns match A target pattern is composed of a between a prefix and a suffix either or both of which may be empty The pattern matches a file name only if the file name starts with the prefix and ends with the suffix without overlap The text between the prefix and the suffix is called the stem Thus when the pattern matches the file name test o the stem is test The pattern rule prerequisites are turned into actual file names by substituting the stem for the character Thus if in the same example one of the prerequisites is written as c it expands to test c When the target pattern does not contain a slash and it usually does not directory names in the file names are removed from the file name before it is compared with the target prefix and suffix After the comparison of the file name to the target pattern the directory names along with the slash that ends them are added on to the prerequisite file names generated from the pattern rule s prerequisite patterns and the file name The directories are ignored only for the purpose of finding an implicit rule to use not in the application of that rule Thus e amp t matches the file name src eat With src a as the stem When prerequisites are turned into file names the directories from the stem are added at the front while the rest of the stem is substituted for the Th
176. lt rm f Here is a list of variables whose values are additional arguments for the programs above The default values for all of these is the empty string unless otherwise noted ARFLAGS 118 185 Flags to give the archive maintaining program default rv r ST9 gmake Reference Manual 10 Implicit Rules 10 4 4 ASFLAGS Extra flags to give to the assembler when explicitly invoked ona s or s file CFLAGS Extra flags to give to the C compiler CXXFLAGS Extra flags to give to the C compiler COFLAGS Extra flags to give to the RCS co program CPPFLAGS Extra flags to give to the C preprocessor and programs that use it the C and Fortran compilers FFLAGS Extra flags to give to the Fortran compiler GFLAGS Extra flags to give to the SCCS get program LDFLAGS Extra flags to give to compilers when they are supposed to invoke the linker 1d LFLAGS Extra flags to give to Lex PFLAGS Extra flags to give to the Pascal compiler RFLAGS Extra flags to give to the Fortran compiler for Ratfor pro grams YFLAGS Extra flags to give to Yacc Chains of implicit rules Sometimes a file can be made by a sequence of implicit rules For example a file N o could be made from N y by running first Yacc and then cc Such a sequence is called a chain If the file N c exists or is mentioned in the makefile no special searching is required make finds that the object file can be made by C compilation from N c
177. make handles multiple vpath directives in the order in which they appear in the makefile multiple directives with the same pattern are independent of each other Thus vpath c foo vpath blish vpath c bar will look for a file ending in c in foo then blish then bar while vpat vpat c foo bar blish N N will look for a file ending in c in foo then bar then blish How directory searches are performed When a prerequisite is found through directory search regardless of type general or selective the pathname located may not be the one that make actually provides you in the prerequisite list Sometimes the path discovered through directory search is thrown away The algorithm make uses to decide whether to keep or abandon a path found via directory search is as follows 1 Ifa target file does not exist at the path specified in the makefile directory search is performed 33 185 4 Writing Rules ST9 gmake Reference Manual 4 4 4 34 185 2 Ifthe directory search is successful that path is kept and this file is tentatively stored as the target All prerequisites of this target are examined using this same method 4 After processing the prerequisites the target may or may not need to be rebuilt lf the target does not need to be rebuilt the path to the file found during directory search is used for any prerequisite lists which contain this target In short if make doesn t need to rebuild the
178. ment variable to make 32 In this case the sub make 169 185 Appendix B Errors Generated by Make ST9 gmake Reference Manual B 14 170 185 doesn t communicate with other make processes and will simply pretend it has two jobs of its own warning jobserver unavailable using j1 Add to parent make rule In order for make processes to communicate the parent will pass information to the child Since this could result in problems if the child process isn t actually a make the parent will only do this if it thinks the child is a make The parent uses the normal algorithms to determine this see Section 5 6 1 How the MAKE variable works on page 55 If the makefile is constructed such that the parent doesn t know the child is a make process then the child will receive only part of the information necessary In this case the child will generate this warning message and proceed with its build in a sequential manner 4 5 9 gmake Reference Manual Appendix C Complex Makefile Example APPENDIX C COMPLEX MAKEFILE EXAMPLE Here is the makefile for the GNU tar program This is a moderately complex makefile Because it is the first target the default goal is a11 An interesting feature of this makefile is that testpad h is a source file automatically created by the testpad program itself compiled from testpad c If you type make or make all then make creates the tar executable the rmt daemon that provides remote tape ac
179. milar The ca11 function can be nested Each recursive invocation gets its own local values for 1 etc that mask the values of higher level ca11 For example here is an implementation of a map function map foreach 2 9 call 1 a Now you can MAP a function that normally takes only one argument such as origin to multiple values in one step ky ST9 gmake Reference Manual 8 Functions to Transform Text 8 7 Note 3 5 11 map origin o map end up with O containing something like file file default A final caution be careful when adding whitespace to the arguments to 11 As with other functions any whitespace contained in the second and subsequent arguments is kept this can cause strange effects It s generally safest to remove all extraneous whitespace when providing parameters to ca11 The origin function The origin function is unlike most other functions in that it does not operate on the values of variables it tells you something about a variable Specifically it tells you where it came from The syntax of the origin function is origin VARIABLE Note that VARIABLE is the name of a variable to inquire about not a reference to that variable Therefore you would not normally use a or parentheses when writing it You can however use a variable reference in the name if you want the name not to be a constant The result o
180. more information An archive member name in an archive cannot contain a directory name but it may be useful in a makefile to pretend that it does If you write an archive member target foo a dir file o make will perform automatic updating with this command ar r foo a dir file o which has the effect of copying the dir file o into a member named file o In connection with such usage the automatic variables sD and F may be useful Updating archive symbol directories An archive file that is used as a library usually contains a special member named SYMDEF that contains a directory of the external symbol names defined by all the other members After you update any other members you need to update ___ SYMDEF so that it will summarize the other members properly This is done by running the ranlib program ranlib ARCHIVEFILE Normally you would put this command in the rule for the archive file and make all the members of the archive file prerequisites of that rule For example libfoo a libfoo a x o libfoo a y o ranlib libfoo a The effect of this is to update archive members x o etc and then update the symbol directory member SYMDEF by running ranlib The rules for updating the members are not shown here most likely you can omit them and use the r 5 9 gmake Reference Manual 11 Updating Archive Files 4 implicit rule which copies files into the archive as described the prece
181. moved If the value of 8 is dir foo o then D is dir This value is if does not contain a slash The file within directory part of the file name of the target If the value of is dir foo othen GF is is equivalent to notdir 8 The directory part and the file within directory part of the stem dir and foo in this example The directory part and the file within directory part of the target archive member name This makes sense only for archive member targets of the form ARCHIVE MEMBER and is useful only when MEMBER may contain a directory name See Sec tion 11 1 Archive members as targets on page 133 The directory part and the file within directory part of the first prerequisite Lists of the directory parts and the file within directory parts of all prerequisites Lists of the directory parts and the file within directory parts of all prerequisites that are newer than the target Note that we use a special stylistic convention when we talk about these automatic variables we write the value of lt rather than variable lt as we would write for ordinary variables such as objects and CFLAGS We think this convention looks more natural in this special case Please do not assume it has a deep significance refers to the variable named just as 5 CFLAGS refers to the variable named CFLAGS You could just as well use lt in place of
182. n Thus the rule foo prog o prog foo 5 5 5 prog foo could be used to compile a program prog c Since spaces before the variable value are ignored in variable assignments the value of oo is precisely c Don t actually write your makefiles this way A dollar sign followed by a character other than a dollar sign open parenthesis or open brace treats that single character as the variable name Thus you could reference the variable x with x However this practice is strongly discouraged except in the case of the automatic variables see Section 10 5 3 Automatic variables on page 123 The two flavors of variables There are two ways that a variable in GNU make can have a value we call them the two flavors of variables The two flavors are distinguished in how they are defined and in what they do when expanded The first flavor of variable is a recursively expanded variable Variables of this sort are defined by lines using see Section 6 5 Setting variables on page 70 or by the define directive see Section 6 8 Defining variables verbatim page 74 The value you specify is installed verbatim if it contains references to other variables these references are expanded whenever this variable is substituted in the course of expanding some other string When this happens it is called recursive expansion For example foo 5 bar bar ugh ugh Huh all echo
183. n commands Programs to build binary packages work by extracting the pre installation and post installation commands is one way of extracting the pre installation commands make n install o a N PRE INSTALL pre install POST INSTALL post install NORMAL INSTALL normal install gawk f pre install awk where the file pre install awk could contain this 0 Nt Nt normal install post install t S on 0 on print 50 0 Nt Nt pre install t on 1 The resulting file of pre installation commands is executed as a shell script as part of installing the binary package 159 185 14 Makefile Conventions 160 185 ST9 gmake Reference Manual 4 ST9 gmake Reference Manual Appendix A Quick Reference APPENDIX A QUICK REFERENCE This appendix summarizes the directives text manipulation functions and special variables which GNU make understands See Section 10 2 Catalog of implicit rules on page 113 and Section 9 7 Summary of options on page 106 for other summaries The following table summarizes the directives that GNU make understands Directives Description define VARIABLE endef Define a multi line recursively expanded variable See Sec tion 5 7 Defining canned command sequences page 61 endif Conditionally evaluate part of the makefile See Chapter 7 Conditional Parts of Makefiles on page 79 include FI
184. n do any of these things and many others The exit status of make is always one of three values 0 The exit status is zero if make is successful 2 The exit status is two if make encounters any errors t will print messages describing the particular errors e 1 The exit status is one if you use the q flag and make determines that some target is not already up to date See Section 9 3 Instead of executing the commands on page 102 Arguments to specify the makefile The way to specify the name of the makefile is with the or 1 option makefile also works For example altmake says to use the file altmake as the makefile If you use the f flag several times and follow each f with an argument all the specified files are used jointly as makefiles If you do not use the f or file flag the default is to try GNUmakefile makefile and Makefile in that order and use the first of these three which exists or can be made see Chapter 3 Writing Makefiles on page 19 Arguments to specify the goals The goals are the targets that make should strive ultimately to update Other targets are updated as well if they appear as prerequisites of goals or prerequisites of prerequisites of goals etc By default the goal is the first target in the makefile not counting targets that start with a period Therefore makefiles are usually written so that the first target is for compiling the entire pro
185. n use the include directive to read them all in See Section 3 3 Including other makefiles on page 20 For example sources foo c bar c include sources c d This example uses a substitution variable reference to translate the list of source files oo c bar c into a list of prerequisite makefiles foo d bar d See Section 6 3 1 Substitution references on 67 for full information on substitution references Since the files are makefiles like any others make will remake them as necessary with no further work from you See Section 3 5 How makefiles are remade on page 22 4 5 9 gmake Reference Manual 5 Writing Commands in Rules 5 1 4 WRITING COMMANDS RULES The commands of a rule consist of shell command lines to be executed one by one Each command line must start with a tab except that the first command line may be attached to the target and prerequisites line with a semicolon in between Blank lines and lines of just comments may appear among the command lines they are ignored But beware an apparently blank line that begins with a tab is not blank It is an empty command see Section 5 8 Using empty commands on page 62 for more information Users use many different shell programs but commands in makefiles are always interpreted by bin sh unless the makefile specifies otherwise See Section 5 2 Command execution on page 50 The shell that is in use determines whether comments can be written
186. nd on this behavior and you want to 57 185 5 Writing Commands in Rules ST9 gmake Reference Manual 5 6 3 58 185 be compatible with old versions of make you can write a rule for the special target EXPORT ALL VARIABLES instead of using the export directive This will be ignored by old makes while the export directive will cause a syntax error Likewise you can use unexport by itself to tell make not to export variables by default Since this is the default behavior you would only need to do this ifexport had been used by itself earlier in an included makefile perhaps You cannot use export and unexport by themselves to have variables exported for some commands and not for others The last export Or unexport directive that appears by itself determines the behavior for the entire run of make As a special feature the variable MAKELEVEL is changed when it is passed down from level to level This variable s value is a string which is the depth of the level as a decimal number The value is 0 for the top level make 1 for a sub make 2 for sub sub make and so on The increment happens when make sets up the environment for a command The main use of MAKELEVEL is to test it in a conditional directive see Chapter 7 Conditional Parts of Makefiles on page 79 this way you can write a makefile that behaves one way if run recursively and another way if run directly by you You can use the variable
187. ng whichever object files need it make decides whether to relink edit This must be done if the file edit does not exist or if any of the object files are newer than it If an object file was just recompiled it is now newer than edit SO edit is relinked Thus if we change the file insert c and run make make will compile that file to update insert o and then link edit If we change the file command h and run make make will recompile the object files command o and 1 then link the file eait Variables make makefiles simpler In our example we had to list all the object files twice in the rule for edit repeated here edit main o kbd o command o display o insert o search o files o utils o edit main o kbd o command o display o insert o search o files o utils o Such duplication is error prone if a new object file is added to the system we might add it to one list and forget the other We can eliminate the risk and simplify the makefile by using a variable Variables allow a text string to be defined once ky ST9 gmake Reference Manual 2 Introduction to Makefiles 2 5 4 and substituted in multiple places later see Chapter 6 How to Use Variables on page 63 It is standard practice for every makefile to have a variable named objects OBJECTS OBJS obj or OBJ which is a list of all object file names We would define such a variable objects with a line like this in
188. nking in one step so that s how it s done Yacc for C programs is made automatically from N by running Yacc with the command YACC YFLAGS Lex for C programs N c is made automatically from N 1 by running Lex The actual command is LEX LFLAGS Lex for Ratfor programs N r is made automatically from N 1 by running Lex The actual command is LEX S LFLAGS The convention of using the same suffix 1 for all Lex files regardless of whether they produce C code or Ratfor code makes it impossible for make to determine automatically which of the two languages you are using in any particular case If make is called upon to remake an object file from a 1 file it must guess which compiler to use It will guess the C compiler because that is more common If you are using Ratfor make sure make knows this by mentioning N r in the makefile Or if you are using Ratfor exclusively with no C files remove c from the list of implicit rule suffixes with SUFFIXES SOUEREOXESZI sO 450 tou 4405 Making Lint Libraries from C Yacc or Lex programs N 1n is made from N c by running lint The precise command is LINT 5 CPPFLAGS i The same command is used on the C code produced from N y orN 1 115 185 10 Implicit Rules ST9 gmake Reference Manual 10 2 13 10 2 14 10 2 15 10 2 16 116 185 TeX and Web N dvi is made from N tex with the command TEX
189. no commands you can give that target empty commands by writing a semicolon see Section 5 8 Using empty commands on page 62 for more information 4 5 9 gmake Reference Manual 10 Implicit Rules 10 2 10 2 1 10 2 2 10 2 3 10 2 4 3 Catalog of implicit rules Here is a catalog of predefined implicit rules which are always available unless the makefile explicitly overrides or cancels them See Section 10 5 6 Canceling implicit rules on page 128 for information on canceling or overriding an implicit rule The r or no builtin rules option cancels all predefined rules Not all of these rules will always be defined even when the r option is not given Many of the predefined implicit rules are implemented in make as suffix rules so which ones will be defined depends on the suffix list the list of prerequisites of the special target SUFFIXES The default suffix list is out 1n 0 c QOO C SD ef 2 yy Sly 08 29 mod Sym def h info dVvi texinfo texi txinfo w ch web sh elc el All of the implicit rules described below whose prerequisites have one of these suffixes are actually suffix rules If you modify the suffix list the only predefined suffix rules in effect will be those named by one or two of the suffixes that are on the list you specify rules whose suffixes fail to be on the list are disabled See Section 10 7 Old fashioned suffix rules on page 129 for full
190. ns You can use the export directive to pass other variables See Section 5 6 2 Communicating variables to a sub make on page 56 for full details Other use of variables from the environment is not recommended It is not wise for makefiles to depend for their functioning on environment variables set up outside their control since this would cause different users to get different results from the same makefile This is against the whole purpose of most makefiles Such problems would be especially likely with the variable SHELL which is normally present in the environment to specify the user s choice of interactive shell It would be very undesirable for this choice to affect make So make ignores the environment value of SHELL except on MS DOS and MS Windows where SHELL is usually not set Target specific variable values Variable values in make are usually global that is they are the same regardless of where they are evaluated unless they re reset of course One exception to that is automatic variables see Section 10 5 3 Automatic variables on page 123 The other exception is target specific variable values This feature allows you to define different values for the same variable based on the target that make is currently building As with automatic variables these values are only available within the context of a targets command script and in other target specific assignments Set a target specific variable value
191. nt for defining canned sequences of commands see Section 5 7 Defining canned command sequences on page 61 The define directive is followed on the same line by the name of the variable and nothing more The value to give the variable appears on the following lines The end of the value is marked by a line containing just the word endef Aside from this difference in syntax define works just like it creates a recursively expanded variable see Section 6 2 The two flavors of variables on page 64 The variable name may contain function and variable references which are expanded when the directive is read to find the actual variable name to use define two lines echo foo echo bar endef The value in an ordinary assignment cannot contain a newline but the newlines that separate the lines of the value in a define become part of the variable s value except for the final newline which precedes the endef and is not considered part of the value The previous example is functionally equivalent to this two lines echo foo echo bar since two commands separated by semicolon behave much like two separate shell commands However note that using two separate lines means make will invoke the shell twice running an independent subshell for each line See Section 5 2 Command execution on page 50 If you want variable definitions made with define to take precedence over command line variable definitions you can use the override d
192. o pattern rule has been found so far try harder For each pattern rule in the list o If the rule is terminal ignore it and go on to the next rule Compute the prerequisite names as before Test whether all the prerequisites exist or ought to exist For each prerequisite that does not exist follow this algorithm recursively to see if the prerequisite can be made by an implicit rule If all prerequisites exist ought to exist or can be made by implicit rules then this rule applies If no implicit rule applies the rule for DEFAULT if any applies In that case give T the same commands that DEFAULT has Otherwise there are no commands for T Once a rule that applies has been found for each target pattern of the rule other than the one that matched or the in the pattern is replaced with s and the resultant file name is stored until the commands to remake the target file T are executed After these commands are executed each of these stored file names are entered into the data base and marked as having been updated and having the same update status as the file T When the commands of a pattern rule are executed for T the automatic variables are set corresponding to the target and prerequisites See Section 10 5 3 Automatic variables on page 123 131 185 10 Implicit Rules 132 185 ST9 gmake Reference Manual 4 5 9 gmake Reference Manual 11 Updating Archive Files 11 Note 4
193. o prevent intolerable confusion it is not permitted to start a conditional in one makefile and end it in another However you may write an include directive within a conditional provided you do not attempt to terminate the conditional inside the included file Conditionals that test flags You can write a conditional that tests make command flags such as t by using the variable MAKEFLAGS together with the indstring function see Section 8 2 Functions for string substitution and analysis on page 86 This is useful when touch is not enough to make a file appear up to date The findstring function determines whether one string appears as a substring of another If you want to test for the t flag use t as the first string and the value of MAKEFLAGS as the other 4 ST9 gmake Reference Manual 7 Conditional Parts of Makefiles For example here is how to arrange to use ranlib t to finish marking an archive file up to date archive a ifneq findstring MAKEFLAGS 1 else endif ttouch archive a archive a ranlib archive a The prefix marks those command lines as recursive so that they will be executed despite use of the t flag See Section 5 6 Recursive use of make on page 55 3 83 185 7 Conditional Parts of Makefiles 84 185 ST9 gmake Reference Manual 4 ST9 gmake Reference Manual 8 Functions to Transform Text 8 8 1 4 FUNCTIONS TO TR
194. o reference is stated explicitly it is computed by expansion of x The reference x here is nested within the outer variable reference The previous example shows two levels of nesting but any number of levels is possible For example here are three levels us UE a x Here the innermost 5 x expands to y so x expands 5 y which turn expands to z now we have z which becomes u References to recursively expanded variables within a variable name are re expanded in the usual fashion For example x 5 yu z Hello x defines a as Hello x becomes y which becomes 5 2 which becomes Hello Nested variable references can also contain modified references and function invocations see Section 8 Functions to Transform Texton page 85 just like any other reference For example using the subst function see Section 8 2 Functions for string substitution and analysis on page 86 x variablel variable2 Hello y subst 1 2 5 z y a z eventually defines a as Hello It is doubtful that anyone would ever want to write a nested reference as convoluted as this one but it works z expands to 5 5 which becomes subst 1 2 x This gets the value variablel from x and changes it by substitution to variable2 so that the entire string becomes 5 variable2 a simple variable reference whose value
195. of the following directories bindir The directory for installing executable programs that users can run This should normally be usr local bin but write it as 5 If you are using Autoconf write it as 4 147 185 14 Makefile Conventions 148 185 sbindir libexecdir ST9 gmake Reference Manual The directory for installing executable programs that can be run from the shell but are only generally useful to system administrators This should normally be usr local sbin but write it as exec_prefix sbin If you are using Autoconf write it as sbindir The directory for installing executable programs to be run by other programs rather than by users This directory should normally be usr local libexec but write it as exec prefix libexec If you are using Autoconf write it as libexecdir Data files used by the program during its execution are divided into categories in two ways e Some files are normally modified by programs others are never normally modified though users may edit some of these Some files are architecture independent and can be shared by all machines at a site some are architecture dependent and can be shared only by machines of the same kind and operating system others may never be shared between two machines This makes for six different possibilities However we want to discourage the use of architecture dependent file
196. ok at additional variables of your own giving the user the ability to control other aspects of how the makefile works by changing the variables When you override a variable with a command argument you can define either a recursively expanded variable or a simply expanded variable The examples shown above make a recursively expanded variable to make a simply expanded variable write instead of But unless you want to include a variable reference or function call in the value that you specify it makes no difference which kind of variable you create r ST9 gmake Reference Manual 9 How to Run Make 9 6 4 There is one way that the makefile can change variable that you have overridden This is to use the override directive which is a line that looks like this override VARIABLE VALUE see Section 6 7 The override directive on page 73 Testing the compilation of a program Normally when an error happens in executing a shell command make gives up immediately returning a nonzero status No further commands are executed for any target The error implies that the goal cannot be correctly remade and make reports this as soon as it knows When you are compiling a program that you have just changed this is not what you want Instead you would rather that make try compiling every file that can be tried to show you as many compilation errors as possible On these occasions you should use the or
197. ommand if either source file has changed since the last make print The automatic variable is used to print only those files that have changed see Section 10 5 3 Automatic variables on page 123 Special built in target names Certain names have special meanings if they appear as targets PHONY The prerequisites of the special target PHONY are considered to be phony targets When it is time to consider such a target make will run its commands unconditionally regardless of whether a file with that name exists or what its last modification time is See Section 4 5 Phony targets on page 36 for more information 39 185 4 Writing Rules ST9 gmake Reference Manual 40 185 SUFFIXES The prerequisites of the special target SUFFIXES are the list of suffixes to be used in checking for suffix rules See Section 10 7 Old fashioned suffix rules on page 129 DEFAULT The commands specified for DEFAULT are used for any target for which no rules are found either explicit rules or implicit rules If DEFAULT commands are specified every file mentioned as a prerequisite but not as a target in a rule will have these commands executed on its behalf See Section 10 8 Implicit rule search algorithm on page 130 PRECIOUS The targets which PRECIOUS depends on are given the following special treatment if make is killed or interrupted during the execution of their commands the target is not deleted See Secti
198. on 5 5 Interrupting or killing make on page 54 Also if the target is an intermediate file it will not be deleted after it is no longer needed as is normally done See Section 10 4 Chains of implicit rules on page 119 for more information You can also list the target pattern of an implicit rule such as as a prerequisite file of the special target PRECIOUS to preserve intermediate files created by rules whose target patterns match that file s name INTERMEDIATE The targets which INTERMEDIATE depends on are treated as intermediate files See Section 10 4 Chains of implicit rules on page 119 for more information INTERMEDIATE With no prerequisites has no effect SECONDARY The targets which SECONDARY depends on are treated as intermediate files except that they are never automatically deleted See Section 10 4 Chains of implicit rules on page 119 for more information SECONDARY With no prerequisites marks all file targets mentioned in the makefile as secondary DELETE ON ERROR If DELETE ON ERROR is mentioned as a target anywhere in the makefile then make will delete the target of a rule if it has changed and its commands exit with a nonzero exit status just as it does when it receives a signal See Section 5 4 Errors in commands on page 53 r 5 9 gmake Reference Manual 4 Writing Rules 4 9 3 If you specify prerequis
199. or is mentioned in the makefile in any of the directories the implicit rule for C compilation is applied The commands of implicit rules normally use automatic variables as a matter of necessity consequently they will use the file names found by directory search with no extra effort Directory search for link libraries Directory search applies in a special way to libraries used with the linker This special feature comes into play when you write a prerequisite whose name is of the form 1NAME You can tell something strange is going on here because the prerequisite is normally the name of a file and the file of a library generally looks like 1ibNAME a not like 1NAME When prerequisite s name has the form 1NAME make handles it specially by searching for the file LibNAME so in the current directory in directories specified by matching vpath search path and the vPATH search path and then in the directories 1ib usr lib and PREFIX l1ib normally usr 1ocal lib but MS DOS MS Windows versions of make behave as if PREFIX is defined to be the root of the DJGPP installation tree If that file is not found then the file 1ibNAME a is searched for in the same directories as above 35 185 4 Writing Rules ST9 gmake Reference Manual 4 5 36 185 For example if there is a usr lib libcurses a library on your system and no usr lib libcurses so file then foo foo c lcurses cc 57
200. orithm because suffix rules are converted to equivalent pattern rules once the makefiles have been read in For an archive member target of the form ARCHIVE MEMBER the following algorithm is run twice first using the entire target name T and second using MEMBER as the target if the first run found no rule 1 Split T into a directory part called p and the rest called N For example if T is src foo o thenD is src and Nis oo o 2 Make a list of all the pattern rules one of whose targets matches T or N If the target pattern contains a slash it is matched against T otherwise against N r 5 9 gmake Reference Manual 10 Implicit Rules 3 If any rule in that list is a match anything rule then remove all non terminal match anything rules from the list Remove from the list all rules with no commands For each pattern rule in the list a Find the stem 5 which is the non empty part of T or matched by the 5 in the target pattern Compute the prerequisite names by substituting s for 5 if the target pattern does not contain a slash append p to the front of each prerequisite name Test whether all the prerequisites exist or ought to exist If a file name is mentioned in the makefile as a target or as an explicit prerequisite then we say it ought to exist If all prerequisites exist or ought to exist or there are no prerequisites then this rule applies If n
201. output text g generate text g subst output 0 gt Q is equivalent to bigoutput text g generate text g big bigoutput littleoutput text g generate text g little littleoutput Here we assume the hypothetical program generate makes two types of output one if given big and one if given little See Section 8 2 Functions for string substitution and analysis on page 86 for an explanation of the subst function Suppose you would like to vary the prerequisites according to the target much as the variable allows you to vary the commands You cannot do this with multiple targets in an ordinary rule but you can do it with a static pattern rule See Section 4 11 Static pattern rules on page 43 Multiple rules for one target One file can be the target of several rules All the prerequisites mentioned in all the rules are merged into one list of prerequisites for the target If the target is older than any prerequisite from any rule the commands are executed There can only be one set of commands to be executed for a file If more than one rule gives commands for the same file make uses the last set given and prints an error message As a special case if the file s name begins with a dot no error message is printed This odd behavior is only for compatibility with other implementations of make There is no reason to write your makefiles this way that is why make gives you an error message An extra
202. owed either use simply expanded variables or use the append operator See Chapter 6 How to Use Variables on page 63 Unterminated variable reference Stop This means you forgot to provide the proper closing parenthesis or brace in your variable or function reference insufficient arguments to function XXX Stop This means you haven t provided the requisite number of arguments for this function See the documentation of the function for a description of its arguments See Section 8 Functions to Transform Text on page 85 missing target pattern Stop multiple target patterns Stop target pattern contains no Stop These are generated for malformed static pattern rules The first means there s no pattern in the target section of the rule the second means there are multiple patterns in the target section and the third means the target doesn t contain a pattern character 5 See Section 4 11 1 Syntax of static pattern rules on page 43 warning jN forced in submake disabling jobserver mode This warning and the next are generated if make detects error conditions related to parallel processing on systems where sub makes can communicate see Section 5 6 3 Communicating options to a sub make on page 58 This warning is generated if a recursive invocation of a make process is forced to have jN in its argument list where N is greater than one This could happen for example if you set the MAKE environ
203. own suffixes When make sees a rule whose target is a known suffix this rule is considered a single suffix rule When make sees a rule whose target is two known suffixes concatenated this rule is taken as a double suffix rule For example c and o are both on the default list of known suffixes Therefore if you define rule whose target is c o make takes it to be a double suffix rule with source suffix c and target suffix Here is the old fashioned way to define the rule for compiling a C source file CC c CFLAGS CPPFLAGS o 508 lt Suffix rules cannot have any prerequisites of their own If they have any they are treated as normal files with funny names not as suffix rules Thus the rule 60 hi CC c CFLAGS CPPFLAGS o lt tells how to make the file from the prerequisite file foo n and is not at all like the pattern rule 9 0 c foo h CC c CFLAGS CPPFLAGS o 0 lt which tells how to make files from c files and makes all files using this pattern rule also depend on foo h 129 185 10 Implicit Rules ST9 gmake Reference Manual 10 8 130 185 Suffix rules with no commands are also meaningless They do not remove previous rules as do pattern rules with no commands see Section 10 5 6 Canceling implicit rules on page 128 They simply enter the suffix or pair of suffixes concatenated as a target in the data base The known suffixes
204. page 49 For example using this canned sequence define frobnicate echo frobnicating target 560 frob step 1 lt o step 1 endef make will not echo the first line the echo command But it will echo the following two command lines On the other hand prefix characters on the command line that refers to a canned sequence apply to every line in the sequence So the rule frob out frob in 5 frobnicate does not echo commands See Section 5 1 Command echoing on page 49 for a full explanation of Using empty commands It is sometimes useful to define commands which do nothing This is done simply by giving a command that consists of nothing but whitespace For example target 9 defines an empty command string for target You could also use a line beginning with a tab character to define an empty command string but this would be confusing because such a line looks empty You may be wondering why you would want to define a command string that does nothing The only reason this is useful is to prevent a target from getting implicit commands from implicit rules or the DEFAULT special target see Chapter 10 Implicit Rules on page 111 and Section 10 6 Defining last resort default rules on page 128 for more information You may be inclined to define empty command strings for targets that are not actual files but only exist so that their prerequisites can be remade However this is not the best wa
205. panded the same way regardless of the form IMMEDIATE IMMEDIATE DEFERRED DEFERRED That is the target and prerequisite sections are expanded immediately and the commands used to construct the target are always deferred This general rule is true for explicit rules pattern rules suffix rules static pattern rules and simple prerequisite definitions 4 ST9 gmake Reference Manual 4 Writing Rules 4 1 4 2 4 WRITING RULES A rule appears in the makefile and says when and how to remake certain files called the rule s targets most often only one per rule It lists the other files that are the prerequisites of the target and commands to use to create or update the target The order of rules is not significant except for determining the default goal the target for make to consider if you do not otherwise specify one The default goal is the target of the first rule in the first makefile If the first rule has multiple targets only the first target is taken as the default There are two exceptions a target starting with a period is not a default unless it contains one or more slashes as well and a target that defines a pattern rule has no effect on the default goal See Section 10 5 Defining and redefining pattern rules on page 121 Therefore we usually write the makefile so that the first rule is the one for compiling the entire program or all the programs
206. ple of a makefile see Appendix C Complex Makefile Example on page 171 When make recompiles the editor each changed C source file must be recompiled If a header file has changed each C source file that includes the header file must be recompiled to be safe Each compilation produces an object file corresponding to the source file Finally if any source file has been recompiled all the object files whether newly made or saved from previous compilations must be linked together to produce the new executable editor What a rule looks like A simple makefile consists of rules with the following format TARGET PREREQUISITES COMMAND A target is usually the name of a file that is generated by a program examples of targets are executable or object files A target can also be the name of an action to carry out such as clean see Section 4 5 Phony targets on page 36 for more information A prerequisite is a file that is used as input to create the target A target often depends on several files A command is an action that make carries out A rule may have more than command each on its own line You need to put a tab character at the beginning of every command line This is an obscurity that catches the unwary Usually a command is in a rule with prerequisites and serves to create a target file if any of the prerequisites change However the rule that specifies commands for the ta
207. ppose the makefile looks like this foo foo o bar o cc o foo foo o bar o S CFLAGS LDFLAGS Because you mention oo o but do not give a rule for it make will automatically look for an implicit rule that tells how to update it This happens whether or not the file currently exists If an implicit rule is found it can supply both commands and one or more prerequisites the source files You would want to write a rule for oo o with no command lines if you need to specify additional prerequisites such as header files that the implicit rule cannot supply 111 185 10 Implicit Rules ST9 gmake Reference Manual Note 112 185 Each implicit rule has a target pattern and prerequisite patterns There may be many implicit rules with the same target pattern For example numerous rules make o files one from a c file with the C compiler another from a file with the Pascal compiler and so on The rule that actually applies is the one whose prerequisites exist or can be made So if you have a file make will run the C compiler otherwise if you have a file foo p make will run the Pascal compiler and so on Of course when you write the makefile you know which implicit rule you want make to use and you know it will choose that one because you know which possible prerequisite files are supposed to exist See Section 10 2 Catalog of implicit rules on page 113 for a catalog of all the predefined implicit
208. quences 61 Using empty commandS s a oh a IN eto 62 How to Use Variables 63 Basics of variable references 2 63 The two flavors of variables 64 Advanced features for reference to variables 67 How variables get their values 40 000 70 Setting variables ac 70 Appending more text to variables 71 The override directive 73 Defining variables verbatim 74 Variables from the environment 2 0 74 Target specific variable values 400 75 Pattern specific variable values 444 76 Conditional Parts of Makefiles 79 Exampl ota conditional Ec pee rete oat 79 Syntax or condillonals 80 Conditionals that test Tags ped tee aped 82 Functions to Transform 85 F riction call hoeta enau iaie 85 Functions for string substitution and analysis 86 F nctions Tor fil dames act EE bep OH ptt s 89 8 4 8 5 8 6 8 7 8 8 8 9 9 91 9 2
209. r is found in a makefile the name of the file and line number containing the problem In the list below these common prefixes are left off FOO Error NN FOO SIGNAL DESCRIPTION These errors are not really make errors at all They mean that a program that make invoked as part of a command script returned a 0 error code Error NN which make interprets as failure or it exited in some other abnormal fashion with a signal of some type See Section 5 4 Errors in commands on page 53 for more information If no is attached to the message then the subprocess failed but the rule in the makefile was prefixed with the special character so make ignored the error missing separator Stop missing separator did you mean TAB instead of 8 spaces Stop This means that make could not understand much of anything about the command line it just read GNU make looks for various kinds of separators TAB characters etc to help it decide what kind of command line it s seeing This means it couldn t find a valid one One of the most common reasons for this message is that you or perhaps your oh so helpful editor as is the case with many MS Windows editors have attempted to indent your command scripts with spaces instead of a TAB character In this case make will use the second form of the error above Remember that every line in the command script must begin with a TAB character Eight spaces do not count See Section
210. r this problem is to give OUTPUT OPTION the value mv 5 Q Variables used by implicit rules The commands in built in implicit rules make liberal use of certain predefined variables You can alter these variables in the makefile with arguments to make or in the environment to alter how the implicit rules work without redefining the rules themselves You can cancel all variables used by implicit rules with the R or no builtin variables option For example the command used to compile a C source file actually says CC CFLAGS CPPFLAGS The default values of the variables used are cc and nothing resulting in the command cc c By redefining CC to ncc you could cause ncc to be used for all C compilations performed by the implicit rule By redefining CFLAGS to be g you could pass the option to each compilation All implicit rules that do C compilation use CC to get the program name for the compiler and all include CFLAGS among the arguments given to the compiler The variables used in implicit rules fall into two classes those that are names of programs like cc and those that contain arguments for the programs like CFLAGS The name of a program may also contain some command arguments but it must start with an actual executable program name If a variable value contains more than one argument separate them with spaces Here is a list of variables used as names of programs in built in rule
211. rd expansion in such places you need to use the wildcard function like this 5 wildcard PATTERN This string used anywhere in a makefile is replaced by a space separated list of names of existing files that match one of the given file name patterns If no existing file name matches a pattern then that pattern is omitted from the output of the wildcard function This is different from how unmatched wildcards behave in rules where they are used verbatim rather than ignored ky 5 9 gmake Reference Manual 4 Writing Rules 4 4 4 4 1 4 use of the wildcard function is to get a list of all the C source files in directory like this 5 wildcard c We can change the list of C source files into a list of object files by replacing the c suffix with o in the result like this S patsubst c 0 wildcard c Here we have used another function patsubst See Section 8 2 Functions for string substitution and analysis on page 86 Thus a makefile to compile all C source files in the directory and then link them together could be written as follows 9 objects patsubst c 0 wildcard c foo 5 cc o foo objects This takes advantage of the implicit rule for compiling C programs so there is no need to write explicit rules for compiling the files See Section 6 2 The two flavors of variables page 64 for an explanation of which is a variant of Searchin
212. rget need not have prerequisites For example the rule containing the delete command associated with the target c1ean does not have prerequisites 11 185 2 Introduction to Makefiles ST9 gmake Reference Manual 2 2 12 185 A rule then explains how and when to remake certain files which are the targets of the particular rule make carries out the commands on the prerequisites to create or update the target A rule can also explain how and when to carry out an action See Section 4 Writing Rules on page 27 A makefile may contain other text besides rules but a simple makefile need only contain rules Rules may look somewhat more complicated than shown in this template but all fit the pattern more or less A simple makefile Here is a straightforward makefile that describes the way an executable file called edit depends on eight object files which in turn depend on eight C source and three header files In this example all the C files include defs h but only those defining editing commands include command h and only low level files that change the editor buffer include buffer h edit main o kbd o command o display o insert o search o files o utils o edit main o kbd o command o display o insert o search o files o utils o main o main c defs h main c kbd o kbd c defs h command h kbd c command o command c defs h command h command c display o display c defs h buffer h
213. rmation set each time you run make You simply put a value for MAKEFLAGS in your environment You can also set MAKEFLAGS in a makefile to specify additional flags that should also be in effect for that makefile You cannot use MFLAGS this way That variable is set only for compatibility make does not interpret a value you set for it in any way When make interprets the value of MAKEFLAGS either from the environment or from a makefile it first adds a hyphen if the value does not already begin with one Then it chops the value into words separated by blanks and parses these words as if they were options given on the command line except that C h o W and their long named versions are ignored and there is no error for an invalid option If you do put MAKEFLAGS in your environment you should be sure not to include any options that will drastically affect the actions of make and undermine the purpose of makefiles and of make itself For instance the t n and q options if put in one of these variables could have disastrous consequences and would certainly have at least surprising and probably annoying effects The print directory option If you use several levels of recursive make invocations the w or print directory option can make the output a lot easier to understand by showing each directory as make starts processing it and as make finishes processing it For example if make w is run in the director
214. rule search see Section 10 1 Using implicit rules on page 111 for more information is apparently done for all targets not just those without commands This means you can do foo o Foo and Unix make will intuit that depends on foo c We feel that such usage is broken The prerequisite properties of make are well defined for GNU make at least and doing such a thing simply does not fit the model GNU make does not include any built in implicit rules for compiling or preprocessing EFL programs If we hear of anyone who is using EFL we will gladly add them It appears that in SVR4 make a suffix rule can be specified with no commands and it is treated as if it had empty commands see Section 5 8 Using empty commands on page 62 for more information For example will override the built in suffix rule We feel that it is cleaner for a rule without commands to always simply add to the prerequisite list for the target The above example can be easily rewritten to get the desired behavior in GNU make Some versions of make invoke the shell with the flag except under k see Section 9 6 Testing the compilation of a program on page 105 The e flag tells the shell to exit as soon as any program it runs returns a nonzero status We feel it is cleaner to write each shell command line to stand on its own and not require this special treatment 4 ST9 gmake Reference Manual 1
215. rule with just prerequisites can be used to give a few extra prerequisites to many files at once For example one usually has a variable named objects containing a list of all the compiler output files in the system being made An easy r 5 9 gmake Reference Manual 4 Writing Rules 4 11 4 11 1 4 way to say that all of them must be recompiled if config h changes is to write the following objects foo o bar o foo o defs h bar o defs h test h objects config h This could be inserted or taken out without changing the rules that really specify how to make the object files making it a convenient form to use if you wish to add the additional prerequisite intermittently Another wrinkle is that the additional prerequisites could be specified with a variable that you set with a command argument to make see Section 9 5 Overriding variables on page 104 For example extradeps objects extradeps means that the command mak xtradeps foo h will consider oo h as a prerequisite of each object file but plain make will not If none of the explicit rules for a target has commands then make searches for an applicable implicit rule to find some commands see Section 10 1 Using implicit rules on page 111 for more information Static pattern rules Static pattern rules are rules which specify multiple targets and construct the prerequisite names for each target based on the target name They are more genera
216. rules Above we said an implicit rule applies if the required prerequisites exist or can be made A file can be made if it is mentioned explicitly in the makefile as a target or a prerequisite or if an implicit rule can be recursively found for how to make it When an implicit prerequisite is the result of another implicit rule we say that chaining is occurring See Section 10 4 Chains of implicit rules on page 119 for more information In general make searches for an implicit rule for each target and for each double colon rule that has no commands A file that is mentioned only as a prerequisite is considered a target whose rule specifies nothing so implicit rule search happens for it See Section 10 8 Implicit rule search algorithm on page 130 for the details of how the search is done Explicit prerequisites do not influence implicit rule search For example consider this explicit rule foo o foo p The prerequisite on oo p does not necessarily mean that make will remake foo o according to the implicit rule to make an object file a file from a Pascal source file a file For example if foo c also exists the implicit rule to make an object file from a C source file is used instead because it appears before the Pascal rule in the list of predefined implicit rules see Section 10 2 Catalog of implicit rules on page 113 for more information If you do not want an implicit rule to be used for a target that has
217. s AR Archive maintaining program default ar AS Program for doing assembly default as Program for compiling C programs default cc 117 185 10 Implicit Rules CXX CO CPP FC PG YACC YACCR MAKEINFO TEXI2DVI WEAVE CWEAVE TANGLE CTANGLE RM ST9 gmake Reference Manual Program for compiling C programs default g Program for extracting a file from RCS default co Program for running the C preprocessor with results to stan dard output default 5 CC Program for compiling or preprocessing Fortran and Ratfor programs default 77 Program for extracting a file from SCCS default get Program to use to turn Lex grammars into C programs or Ratfor programs default lex Program for compiling Pascal programs default pc Program to use to turn grammars into programs default yacc Program to use to turn grammars into Ratfor pro grams default yacc r Program to convert a Texinfo source file into an Info file default makeinfo Program to make TeX DVI files from TeX source default tex Program to make TeX DVI files from Texinfo source default texi2dvi Program to translate Web into TeX default weave Program to translate C Web into TeX default cweave Program to translate Web into Pascal default tangle Program to translate C Web into C default ctangle Command to remove a file defau
218. s These options are ignored for compatibility with other versions of make Change to directory DIR before reading the makefiles If multiple options are specified each is interpreted relative to the previous one C C etc is equivalent to C etc This is typically used with recursive invocations of make see Section 5 6 Recursive use of make on page 55 Print debugging information in addition to nor mal processing The debugging information says which files are being considered for remaking which file times are being compared and with what results which files actually need to be remade which implicit rules are consid ered and which are applied everything inter esting about how make decides what to do Give variables taken from the environment pre cedence over variables from makefiles See Section 6 9 Variables from the environment on page 74 Read the file named FILE as a makefile See Chapter 3 Writing Makefiles on page 19 Remind you of the options that make under stands and then exit Ignore all errors in commands executed to remake files See Section 5 4 Errors in com mands on page 53 4 3 ST9 gmake Reference Manual I DIR include dir DIR j JOBS jobs JOBS k keep going 1 LOAD 1 LOAD max 1load LOAD n just print dry run recon o FILE old file FILE assume old FILE 9 How to Run Make
219. s aside from object files and libraries It is much cleaner to make other data files architecture independent and it is generally not hard Therefore here are the variables Makefiles should use to specify directories datadir The directory for installing read only architecture independent data files This should normally be usr local share but write it as prefix share If you are using Autoconf write it as datadir As special exception see infodir and includedir below 4 ST9 gmake Reference Manual 4 sysconfdir sharedstatedir localstatedir libdir infodir 14 Makefile Conventions The directory for installing read only data files that pertain to a single machine that is to say files for configuring a host Mailer and network configuration files etc passwd and so forth belong here All the files in this directory should be ordinary ASCII text files This directory should normally be usr local etc but write it as prefix etc If you are using Autoconf write it as sysconfdir Do not install executables here in this directory they probably belong libexecdir or Also do not install files that are modified in the normal course of their use programs whose purpose is to change the configuration of the system excluded Those probably belong localstatedir The directory for installing architecture independent data files which the progr
220. s lispdir In order to make lispdir work you need the following lines in your configure in file lispdir S datadir emacs site lisp AC SUBST lispdir The directory for installing header files to be included by user programs with the C include preprocessor directive This should normally be usr local include but write it as prefix include If you are using Autoconf write itas includedir Most compilers other than GCC do not look for header files in directory usr local include So installing the header files this way is only useful with GCC Sometimes this is not a problem because some libraries are only really intended to work with GCC But some libraries are intended to work with other compilers They should install their header files in two places one specified by includedir and one specified by o1dincludedir 4 ST9 gmake Reference Manual 14 Makefile Conventions 4 oldincludedir directory for installing include header files for use with compilers other than GCC This should normally be usr include If you are using Autoconf you can write it as oldincludedir The Makefile commands should check whether the value of oldincludedir is empty If it is they should not try to use it they should cancel the second installation of the header files A package should not replace an existing header in this directory unless the header came from the same package Thus
221. s and functions when the variable is defined The actual value of the simply expanded variable is the result of expanding the text that you write It does not contain any references to other variables it contains their values as of the time this variable was defined Therefore x foo y x bar x later is equivalent to y foo bar x later When a simply expanded variable is referenced its value is substituted verbatim Here is a somewhat more complicated example illustrating the use of in conjunction with the shell function See Section 8 8 The shell function on page 97 This example also shows use of the variable MAKELEVEL which is changed when it is passed down from level to level See Section 5 6 2 Communicating variables to a sub make on page 56 for information about MAKELEVEL ifeq 0 MAKELEVEL cur dir she pwd whoami S she whoami host type sh arch MAKE MAKE host type host type whoami whoami endif 65 185 6 How to Use Variables ST9 gmake Reference Manual Note 66 185 An advantage of this use of is that a typical descend into a directory command then looks like this S subdirs MAKE cur dir cur dir S C 0 all Simply expanded variables generally make complicated makefile programming more predictable because they work like variables in most programming languages The
222. s makefiles When the makefile name is specified explicitly as a goal the options t so on do apply to them Thus make f mfile n mfile foo would read the makefile mfile print the commands needed to update it without actually running them and then print the commands needed to update oo without running them The commands for oo will be those specified by the existing contents of mfile Overriding part of another makefile Sometimes it is useful to have a makefile that is mostly just like another makefile You can often use the include directive to include one in the other and add more targets or variable definitions However if the two makefiles give different commands for the same target make will not let you just do this But there is another way In the containing makefile the one that wants to include the other you can use a match anything pattern rule to say that to remake any target that cannot be made from the information in the containing makefile make should look in another makefile See Section 4 11 Static pattern rules on page 43 for more information on pattern rules For example if you have a makefile called Makefile that says how to make the target foo and other targets you can write a makefile called GNUmakefile that contains foo frobnicate gt foo force 85 MAKE f Makefile force If you say make foo make will find GNUmakefile read it and see that to make foo it needs to run
223. s on page 28 For example foolib o expands to all existing members of the foolib archive whose names end in perhaps foolib hack o foolib kludge o Implicit rule for archive member targets Recall that a target that looks like A M stands for the member named M in the archive file A When make looks for an implicit rule for such a target as a special feature it considers implicit rules that match M as well as those that match the actual target A M 133 185 11 Updating Archive Files ST9 gmake Reference Manual 11 2 1 134 185 This causes one special rule whose target is to match This rule updates the target A by copying the into the archive For example it will update the archive member target foo a bar o by copying the file bar o into the archive foo a as a member named bar o When this rule is chained with others the result is very powerful Thus make foo a bar o the quotes are needed to protect the and from being interpreted specially by the shell in the presence of a file bar c is enough to cause the following commands to be run even without a makefile cc c bar c o bar o ar r foo a bar o rm bar o Here make has envisioned the bar o as an intermediate file See Section 10 4 Chains of implicit rules on page 119 for more information Implicit rules such as this one are written using the automatic variable 5 See Section 10 5 3 Automatic variables on page 123 for
224. s verbatim on page 74 Defining for a complete explanation of define The first command in this example runs Yacc on the first prerequisite of whichever rule uses the canned sequence The output file from Yacc is always named y tab c The second command moves the output to the rule s target file name To use the canned sequence substitute the variable into the commands of a rule You can substitute it like any other variable see Section 6 1 Basics of variable references on page 63 Because variables defined by define are recursively expanded variables all the variable references you wrote inside the define are expanded now For example foo c foo y run yacc foo y will be substituted for the variable when it occurs in run yacc s value and oo cfor 6 This is a realistic example but this particular one is not needed in practice because make has an implicit rule to figure out these commands based on the file names involved see Section 10 1 Using implicit rules on page 111 for more information In command execution each line of a canned sequence is treated just as if the line appeared on its own in the rule preceded by a tab In particular make invokes a separate subshell for each line You can use the special prefix characters that 61 185 5 Writing Commands in Rules ST9 gmake Reference Manual 5 8 affect command lines 8 and on each line of a canned sequence See Chapter 5 Writing Commands in Rules on
225. search path for included makefiles See Section 3 3 Including other makefiles on page 20 Specify extra makefiles to read with an environment variable See Section 3 4 The variable MAKEFILES on page 22 Strip leading sequences of from file names so that FILE and FILE are 139 185 12 Features of GNU Make ST9 gmake Reference Manual 140 185 considered to be the same file Use a special search method for library prerequisites written in the form 1NAME See Section 4 4 6 Directory search for link libraries on page 35 Allow suffixes for suffix rules see Section 10 7 Old fashioned suffix rules on page 129 to contain any characters In other versions of make they must begin with and not contain any characters Keep track of the current level of make recursion using the variable MAKELEVEL See Section 5 6 Recursive use of make on page 55 Provide any goals given on the command line in the variable MAKECMDGOALS See Section 9 2 Arguments to specify the goals on page 99 Specify static pattern rules See Section 4 11 Static pattern rules on page 43 Provide selective vpath search See Section 4 4 Searching directories for prerequisites on page 31 Provide computed variable references See Section 6 1 Basics of variable references on page 63 Update makefiles See Section 3 5 How makefiles are remade on page 22 System V make has a very very limited form of this functional
226. sembles the for command in the shell sh and the foreach command in the C shell csh The syntax of the foreach function is 5 foreach VAR LIST TEXT The first two arguments VAR and LIST are expanded before anything else is done note that the last argument TEXT is not expanded at the same time Then for each word of the expanded value of LIST the variable named by the expanded value of VAR is set to that word and TEXT is expanded Presumably TEXT contains references to that variable so its expansion will be different each time The result is that TEXT is expanded as many times as there are whitespace separated words in LIST The multiple expansions of TEXT are concatenated with spaces between them to make the result of foreach This simple example sets the variable files to the list of all files in the directories in the list dirs dirs files 5 dir dirs wildcard 5 TEXT is wildcard 5 The first repetition finds the value a for dir it produces the same result as wildcard a the second repetition produces the result of wildcard b and the third that of S wildcard c This example has the same result except for setting dirs as the following example files wildcard a b c d When TEXT is complicated you can improve readability by giving it a name with an additional variable find files 5 1
227. ses is handled by two pattern rules for extraction from SCCS in combination with the general feature of rule chaining See Section 10 4 Chains of implicit rules on page 119 for more information In System V make the string 550 has the strange meaning that in the prerequisites of a rule with multiple targets it stands for the particular target that is being processed This is not defined in GNU make because should always stand for an ordinary It is possible to get portions of this functionality through the use of static pattern rules see Section 4 11 Static pattern rules on page 43 The System V make rule targets 0 0 lib a can be replaced with the GNU make static pattern rule targets 0 lib a In System V and 4 3 BSD make files found by vPATH search see Section 4 4 Searching directories for prerequisites on page 31 have their names changed inside command strings We feel it is much cleaner to always use automatic variables and thus make this feature obsolete In some Unix makes the automatic variable appearing in the prerequisites of a rule has the amazingly strange feature of expanding to the full name of 141 185 13 Incompatibilities Missing Features ST9 gmake Reference Manual 142 185 the target of that rule We cannot imagine what went on in the minds of Unix make developers to do this it is utterly inconsistent with the normal definition of In some Unix makes implicit
228. sponding to each source file For each source file NAME c there is a makefile NAME d which lists what files the object file NAME o depends on That way only the source files that have changed need to be re scanned to produce the new prerequisites Here is the pattern rule to generate a file of prerequisites i e a makefile called NAME d from a C source file called NAME c d set e CC M CPPFLAGS lt sed s N S N N o 1 N1 o 80 g gt 0 s 6 rm f 58 See Section 4 11 Static pattern rules on page 43 for information on defining pattern rules The e flag to the shell makes it exit immediately if the CC command fails exits with a nonzero status Normally the shell exits with the status of the last command in the pipeline sed in this case so make would not notice a nonzero status from the compiler With the GNU C compiler you may wish to use the flag instead This omits prerequisites on system header files The purpose of the sed command is to translate for example main o main c defs h into main o main d main c defs h This makes each file depend on all the source and header files that the corresponding o file depends on make then knows it must regenerate the prerequisites whenever any of the source or header files changes 47 185 4 Writing Rules ST9 gmake Reference Manual 48 185 Once you ve defined the rule to remake the d files you the
229. stpad testpad testpad testpad o CC o 8 testpad o TAGS SRCS etags SRCS clean rm f o tar rmt testpad testpad h core distclean clean rm TAGS Makefile config status realclean distclean rm tar info shar SRCS AUX shar SRCS AUX compress gt tar sed version string d 60 79 AN 4 ST9 gmake Reference Manual Appendix C Complex Makefile Example version c shar Z dist SRCS AUX echo tar sed version string d zectsSApT0 9s TE NETI E TENS e q version c gt fname rm rf cat fname mkdir cat fname in SRCS 5 0 cat fname tar chzf cat fname tar Z cat fname rm rf cat fname fname tar zoo S SRCS AUX rm rf tmp dir mkdir tmp dir rm tar zoo for X SRCS AUX do echo SSX sed s M SSX tmp dir X done cd tmp dir zoo aM tar zoo rm rf tmp dir 3 175 185 Appendix C Complex Makefile Example 176 185 ST9 gmake Reference Manual 4 5 9 gmake Reference Manual Product Support PRODUCT SUPPORT Software Updates You can get software updates from the ST Internet web site http mcu st com For information on firmware and hardware revisions call your distributor or ST using the contact list given above If you experience any problems with a software tool contact the distributor or ST sales
230. t is deleting Ordinarily a file cannot be intermediate if it is mentioned in the makefile as a target or prerequisite However you can explicitly mark a file as intermediate by listing it as a prerequisite of the special target INTERMEDIATE This takes effect even if the file is mentioned explicitly in some other way You can prevent automatic deletion of an intermediate file by marking it as a secondary file To do this list it as a prerequisite of the special target SECONDARY When a file is secondary make will not create the file merely because it does not already exist but make does not automatically delete the file Marking a file as secondary also marks it as intermediate You can list the target pattern of an implicit rule such as as a prerequisite of the special target PRECIOUS to preserve intermediate files made by implicit rules whose target patterns match that file s name see Section 5 5 Interrupting or killing make on page 54 A chain can involve more than two implicit rules For example it is possible to make a file foo from RCS foo y v by running RCS Yacc and cc Then both foo y and oo c are intermediate files that are deleted at the end No single implicit rule can appear more than once in a chain This means that make will not even consider such a ridiculous thing as making oo from by running the linker twice This constraint has the added benefit of prevent
231. target then you use the path found via directory search b If the target does need to be rebuilt is out of date the pathname found during directory search is thrown away and the target is rebuilt using the file name specified in the makefile In short if make must rebuild then the target is rebuilt locally not in the directory found via directory search This algorithm may seem complex but in practice it is quite often exactly what you want Other versions of make use a simpler algorithm if the file does not exist and it is found via directory search then that pathname is always used whether or not the target needs to be built Thus if the target is rebuilt it is created at the pathname discovered during directory search If in fact this is the behavior you want for some or all of your directories you can use the GPATH variable to indicate this to make GPATH has the same syntax and format as vPATH that is a space or colon delimited list of pathnames If an out of date target is found by directory search in a directory that also appears in GPATH then that pathname is not thrown away The target is rebuilt using the expanded path Writing shell commands with directory search When a prerequisite is found in another directory through directory search this cannot change the commands of the rule they will execute as written Therefore you must write the commands with care so that they will look for the prerequisite in
232. thing rules are used for making files containing specific types of data such as executable files and a file name with a recognized suffix indicates some other specific type of data such as a C source file Special built in dummy pattern rules are provided solely to recognize certain file names so that non terminal match anything rules will not be considered These dummy rules have no prerequisites and no commands and they are ignored for all other purposes For example the built in implicit rule p exists to make sure that Pascal source files such as oo p match a specific target pattern and thereby prevent time from being wasted looking for oo p o or ToO Dummy pattern rules such as the for are made for every suffix listed as valid for use in suffix rules see Section 10 7 Old fashioned suffix rules on page 129 127 185 10 Implicit Rules ST9 gmake Reference Manual 10 5 6 10 6 128 185 Canceling implicit rules You can override a built in implicit rule or one you have defined yourself by defining a new pattern rule with the same target and prerequisites but different commands When the new rule is defined the built in one is replaced The new rule s position in the sequence of implicit rules is determined by where you write the new rule You can cancel a built in implicit rule by defining a pattern rule with the same target and prerequisites but no commands For example the following wo
233. type of delimiter is matched to find the end of the reference The text written for each argument is processed by substitution of variables and function calls to produce the argument value which is the text on which the function acts The substitution is done in the order in which the arguments appear Commas and unmatched parentheses or braces cannot appear in the text of an argument as written leading spaces cannot appear in the text of the first argument as written These characters can be put into the argument value by variable substitution First define variables comma and space whose values are isolated comma and space characters then substitute these variables where such characters are wanted like this 85 185 8 Functions to Transform Text ST9 gmake Reference Manual 8 2 86 185 comma empty space S empty S empty foo a bar subst space comma foo bar is now a b c Here the subst function replaces each space with a comma through the value of foo and substitutes the result Functions for string substitution and analysis Here are some functions that operate on strings subst FROM TO TEXT Performs a textual replacement on the text TEXT each occurrence of FROM is replaced by To The result is substituted for the function call For example subst ee EE feet on the street substitutes the string EEt on the strEEt patsubst PATTE
234. uld cancel the rule that runs the assembler 9 9 5 5 5 Defining last resort default rules You can define a last resort implicit rule by writing a terminal match anything pattern rule with no prerequisites see Section 10 5 5 Match anything pattern rules on page 126 This is just like any other pattern rule the only thing special about it is that it will match any target So such a rule s commands are used for all targets and prerequisites that have no commands of their own and for which no other implicit rule applies For example when testing a makefile you might not care if the source files contain real data only that they exist Then you might do this touch 8 to cause all the source files needed as prerequisites to be created automatically You can instead define commands to be used for targets for which there are no rules at all even ones which don t specify commands You do this by writing a rule for the target DEFAULT Such a rule s commands are used for all prerequisites which do not appear as targets in any explicit rule and for which no implicit rule applies Naturally there is no DEFAULT rule unless you write one If you use DEFAULT with no commands or prerequisites DEFAULT the commands previously stored for DEFAULT are cleared Then make acts as if you had never defined DEFAULT at all If you do not want a target to get the commands from a match anything pattern rule Or D
235. ules ST9 gmake Reference Manual 10 5 2 122 185 Pattern rules may have more than one target Unlike normal rules this does not act as many different rules with the same prerequisites and commands If a pattern rule has multiple targets make knows that the rule s commands are responsible for making all of the targets The commands are executed only once to make all the targets When searching for a pattern rule to match a target the target patterns of a rule other than the one that matches the target in need of a rule are incidental make worries only about giving commands and prerequisites to the file presently in question However when this file s commands are run the other targets are marked as having been updated themselves The order in which pattern rules appear in the makefile is important since this is the order in which they are considered Of equally applicable rules only the first one found is used The rules you write take precedence over those that are built in Note however that a rule whose prerequisites actually exist or are mentioned always takes priority over a rule with prerequisites that must be made by chaining other implicit rules Pattern rule examples Here are some examples of pattern rules actually predefined in make First the rule that compiles c files into o files 9 9 S0 CC c 5 5 CPPFLAGS lt o defines a rule that can make any file x o from x c The command uses t
236. ules on page 117 Setting variables To set a variable from the makefile write a line starting with the variable name followed by or Whatever follows the or on the line becomes the value For example objects main o foo o bar o utils o defines a variable named objects Whitespace around the variable name and immediately after the is ignored r ST9 gmake Reference Manual 6 How to Use Variables 6 6 4 Variables defined with are recursively expanded variables Variables defined with are simply expanded variables these definitions can contain variable references which will be expanded before the definition is made See Section 6 2 The two flavors of variables on page 64 The variable name may contain function and variable references which are expanded when the line is read to find the actual variable name to use There is no limit on the length of the value of a variable except the amount of swapping space on the computer When a variable definition is long it is a good idea to break it into several lines by inserting backslash newline at convenient places in the definition This will not affect the functioning of make but it will make the makefile easier to read Most variable names are considered to have the empty string as a value if you have never set them Several variables have built in initial values that are not empty but you can set them in the usual ways see Section 10 3 Variables used
237. very time you add or remove an include To avoid this hassle most modern C compilers can write these rules for you by looking at the 4 include lines in the source files Usually this is done with the M option to the compiler For example the command cc M main c generates the output main o main c defs h Thus you no longer have to write all those rules yourself The compiler will do it for you Such a prerequisite constitutes mentioning main o in a makefile so it can never be considered an intermediate file by implicit rule search This means that make won t ever ky 5 9 gmake Reference Manual 4 Writing Rules 4 remove the file after using it see Section 10 4 Chains of implicit rules on page 119 for more information With old make programs it was traditional practice to use this compiler feature to generate prerequisites on demand with a command like make depend That command would create a file depend containing all the automatically generated prerequisites then the makefile could use include to read them in see Section 3 3 Including other makefiles on page 20 In GNU make the feature of remaking makefiles makes this practice obsolete you need never tell make explicitly to regenerate the prerequisites because it always regenerates any makefile that is out of date See Section 3 5 How makefiles are remade on page 22 The practice we recommend for automatic prerequisite generation is to have one makefile corre
238. w do you write the cc command so that it operates on the right source file name You cannot write the name in the command because the name is different each time the implicit rule is applied What you do is use a special feature of make the automatic variables These variables have values computed afresh for each rule that is executed based on the target and prerequisites of the rule In this example you would use 6 for the object file name and for the source file name Here is a list of automatic variables sg The file name of the target of the rule If the target is an archive member then 54 is the name of the archive file In a pattern rule that has multiple targets see Section 10 5 1 Introduction to pattern rules on page 121 is the name of whichever target caused the rule s commands to be run lt gt The target member name when the target is archive member See Chapter 11 Updating Archive Files on page 133 For example if the target is foo a bar o then is bar o and 5015 5 is empty when the target is not an archive member lt The name of the first prerequisite If the target got its commands from an implicit rule this will be the first prerequisite added by the implicit rule see Section 10 Implicit Rules on page 111 5 The names of all the prerequisites that are newer than the target with spaces between them For prerequisites which are archive members only the member named
239. what commands just print would be used to make the targets up to date but dry run not actually execute them recon t Touch The activity is to mark the targets as up touch to date without actually changing them In other words make pretends to compile the targets but does not really change their contents q Question The activity is to find out silently question whether the targets are up to date already but execute no commands in either case In other words neither compilation nor output will occur W FILE What if Each w flag is followed by a file name what if FILE The given files modification times are recorded assume new FILE by make as being the present time although the new file FILE actual modification times remain the same You can use the w flag in conjunction with the n flag to see what would happen if you were to modify specific files With the n flag make prints the commands that it would normally execute but does not execute them With the t flag make ignores the commands in the rules and uses in effect the command t ouch for each target that needs to be remade The touch command is also printed unless s or SILENT is used For speed make does not actually invoke the program touch It does the work directly With the flag make prints nothing and executes no commands but the exit status code it returns is zero if and only if the targets to be considered are
240. with word E inclusive The legitimate values of S and E start from 1 If 5 is bigger than the number of words in TEXT the value is empty If E is bigger than the number of words in TEXT words up to the end of TEXT are returned If 5 is greater than make swaps them for you For example wordlist 2 3 foo bar baz returns bar baz words TEXT Returns the number of words in TEXT Thus the last word of TEXT is word S words TEXT TEXT firstword NAMES The argument NAMES is regarded as a series of names separated by whitespace The value is the first name in the series The rest of the names are ignored For example S firstword foo bar produces the result foo Although irstword TEXT is the same as word 1 TEXT the firstword function is retained for its simplicity 91 185 8 Functions to Transform Text ST9 gmake Reference Manual 8 4 92 185 wildcard PATTERN The argument PATTERN is a file name pattern typically containing wildcard characters as in shell file name patterns The result of wildcard is a space separated list of the names of existing files that match the pattern See Section 4 3 Using wildcard characters in file names on page 28 The foreach function The foreach function is very different from other functions It causes one piece of text to be used repeatedly each time with a different substitution performed on it It re
241. xample consider a directory containing several programs with a makefile that starts like this PHONY all all size nm ld ar as If you are working on the program size you might want to say make size so that only the files of that program are recompiled Another use of specifying a goal is to make files that are not normally made For example there may be a file of debugging output or a version of the program that is compiled specially for testing which has a rule in the makefile but is not a prerequisite of the default goal Another use of specifying a goal is to run the commands associated with a phony target see Section 4 5 Phony targets on page 36 for more information or empty target see Section 4 7 Empty target files to record events on page 39 Many makefiles contain a phony target named clean which deletes everything except source files Naturally this is done only if you request it explicitly with make clean Following is a list of typical phony and empty target names See Section ky ST9 gmake Reference Manual 3 11 clean mostlyclean distclean realclean clobber install print tar shar dist TAGS check test 9 How to Run Make 14 5 Standard targets for users on page 153 for a detailed list of all the standard target names which GNU software packages use Make all the top level targets the makefile knows about Delete all files that are normally created by running make Li
242. y You can use this function in a conditional to test for the presence of a specific substring in a given string Thus the two examples S findstring a a b c S findstring a b c 87 185 4 8 Functions to Transform Text ST9 gmake Reference Manual 88 185 produce the values a and the empty string respectively See Section 7 3 Conditionals that test flags on page 82 for a practical application of findstring filter PATTERN TEXT Returns all whitespace separated words in TEXT that do match any of the PATTERN words removing any words that do not match The patterns are written using just like the patterns used in the pat subst function above The ilter function can be used to separate out different types of strings such as file names in a variable For example Sources foo c bar c baz s ugh h foo 5 sources cc filter c s sources o foo says that foo depends of foo c bar c baz s and ugh h but only oo c bar c baz s should be specified in the command to the compiler filter out PATTERN TEXT Returns all whitespace separated words in TEXT that do not match any of the PATTERN Words removing the words that do match one or more This is the exact opposite of the filter function Removes all whitespace separated words in TEXT that do match the PATTERN words returning only the words that do not match This is the exact opposite of the filter function
243. y u gnu make make will print a line of the form make Entering directory u gnu make before doing anything else and a line of the form make Leaving directory u gnu make when processing is completed Normally you do not need to specify this option because make does it for you w is turned on automatically when you use the C option and in sub makes make r 5 9 gmake Reference Manual 5 Writing Commands in Rules 5 7 3 will not automatically turn on if you also use s which says to be silent or if you use no print directory to explicitly disable it Defining canned command sequences When the same sequence of commands is useful in making various targets you can define it as a canned sequence with the define directive and refer to the canned sequence from the rules for those targets The canned sequence is actually a variable so the name must not conflict with other variable names Here is an example of defining a canned sequence of commands define run yacc firstword mv y tab c 8 endef Here run yacc is the name of the variable being defined endef marks the end of the definition the lines in between are the commands The define directive does not expand variable references and function calls in the canned sequence the characters parentheses variable names and so on all become part of the value of the variable you are defining See Section 6 8 Defining variable
244. y allow you to redefine a variable using its own value or its value processed in some way by one of the expansion functions and to use the expansion functions much more efficiently see Section 8 Functions to Transform Text on page 85 You can also use them to introduce controlled leading whitespace into variable values Leading whitespace characters are discarded from your input before substitution of variable references and function calls this means you can include leading spaces in a variable value by protecting them with variable references like this nullstring space S nullstring end of the line Here the value of the variable space is precisely one space The comment end of the line is included here just for clarity Since trailing space characters are not stripped from variable values just a space at the end of the line would have the same effect but be rather hard to read If you put whitespace at the end of a variable value it is a good idea to put a comment like that at the end of the line to make your intent clear Conversely if you do want any whitespace characters at the end of your variable value you must remember not to put a random comment on the end of the line after some whitespace such as this dir foo bar directory to put the frobs in Here the value of the variable dir is foo bar with four trailing spaces which was probably not the intention Imagine something like 5 dir file
245. y from N s by running the assembler as The precise command is 5 5 5 ASFLAGS N s is made automatically from N S by running the C preprocessor cpp The precise command is CPP CPPFLAGS Linking a single object file N is made automatically from by running the linker usually called 1d via the C compiler The precise command used is CC LDFLAGS N o LOADLIBES LDLIBS This rule does the right thing for a simple program with only one source file It will also do the right thing if there are multiple object files presumably coming from various other source files one of which has a name matching that of the executable file Thus ye O20 when x c y c and z c all exist will execute GC x CC e y o O0 yao COE zc LO Wiz rm f x o rm y o rm f z o 4 5 9 gmake Reference Manual 10 Implicit Rules 10 2 9 10 2 10 10 2 11 10 2 12 4 In more complicated cases such as when there is no object whose name derives from the executable file name you must write an explicit command for linking Each kind of file automatically made into o object files will be automatically linked by using the compiler CC FC or PC the C compiler CC is used to assemble s files without the c option This could be done by using the o object files as intermediates but it is faster to do the compiling and li
246. y to do that because the prerequisites may not be remade properly if the target file actually does exist See Section 4 5 Phony targets on page 36 for a better way to do this 4 62 185 ST9 gmake Reference Manual 6 How to Use Variables 6 1 3 HOW USE VARIABLES A variable is a name defined in a makefile to represent a string of text called the variable s value These values are substituted by explicit request into targets prerequisites commands and other parts of the makefile In some other versions of make variables are called macros Variables and functions in all parts of a makefile are expanded when read except for the shell commands in rules the right hand sides of variable definitions using and the bodies of variable definitions using the define directive Variables can represent lists of file names options to pass to compilers programs to run directories to look in for source files directories to write output in or anything else you can imagine A variable name may be any sequence of characters not containing or leading or trailing whitespace However variable names containing characters other than letters numbers and underscores should be avoided as they may be given special meanings in the future and with some shells they cannot be passed through the environment to a sub make see Section 5 6 2 Communicating variables to a sub make on page 56 Variable names are case sensitiv

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