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Cygwin User's Guide

1. If no option is given change USER s password If no user name is given operate on current user System operations must not be mixed with user operations Don t specify a USER when triggering a system operation passwd changes passwords for user accounts A normal user may only change the password for their own account but administrators may change passwords on any account passwd also changes account information such as password expiry dates and intervals For password changes the user is first prompted for their old password if one is present This password is then encrypted and compared against the stored password The user has only one chance to enter the correct password The administrators are permitted to bypass this step so that forgotten passwords may be changed The user is then prompted for a replacement password passwd will prompt twice for this replacement and compare the second entry against the first Both entries are required to match in order for the password to be changed After the password has been entered password aging information is checked to see if the user is permitted to change their password at this time If not passwd refuses to change the password and exits To get current password status information use the s option Administrators can use passwd to perform several account maintenance functions users may perform some of these functions on their own accounts Accounts may be locked with the 1 f
2. HQ 54 37 9 pass Wd css och A tn Bese dest ashes tup be Se A eB Ae NRI 57 SIE I 59 3 1 regtool zn RR ogee a PN ee Ro ee ee ea 59 3 7 125 SCA E E t eee e heeds Ne deett cs 61 BAS ESS pis Ah net eae ete ata Sea eA ee eed hu de 63 BTA SACS E 66 SPAS 5umount sca Sek BR Ra SR a 67 3 8 Using Cygwin effectively with Windows ss 67 3 8 T Pathnamesz o non bee EE 68 3 82 Console BFOBrAIS oe et De REPE RR reete nee Te nud 68 3 8 3 Cygwin and Windows Networking ss 69 3 8 4 Th cyg tils package eee eret e d tte eti neces 69 3 8 5 Creating shortcuts with cygutils ss 69 3 8 6 Printing With Cygutils seo e Ree ere t qe e esee b ies 70 4 Programming with Cygwin e eeeeeeee eerte eese eerta tatnen sensn tn sata stata stata setae tasse tainen sensn stata ana 71 4 1 Using GCC with Cygwin iii nee 71 4 1 1 Console Mode Applications sentis hentai ed rete een 71 4 1 2 GUI Mode Applications ss eene nennen nennen renes enne 71 4 2 Debugging Cys Win Programs eie rrt pete nete e ecrire tn 73 4 3 Building and Using DLLs sise 74 43 1 Buildmg DEUS iss 5 iine pa eed et Qr ORDEI 75 4 3 2 Linking Against DLE mete eite ep tec Rte bita fine 76 4 4 Defining Windows Resources siennes 77 List of Examples 2 T fete passwd cede nup USD Ne Ia retin Ree e Ee 20 2 2 JetcI gyOUD c LEE ee ot esi Pe pe
3. Usage strace exe OPTIONS p pid Trace system calls and signals b buffer size SIZE set size of output file buffer d no delta don t display the delta t microsecond timestamp E trace children trace child processes toggle default true h help output usage information and exit m mask MASK set message filter mask n crack error numbers output descriptive text instead of error numbers for Windows errors o output FILENAME set output file to FILENAME p pid n attach to executing program with cygwin pid n Sy flush period PERIOD flush buffered strace output every PERIOD secs t timestamp use an absolute hh mm ss timestamp insted of the default microsecond timestamp Implies d T toggle toggle tracing in a process already being traced Requires p pid v version output version information and exit W new window spawn program under test in a new window MASK can be any combination of the following mnemonics and or hex values Ox is optional Combine masks with or like so mask wm system malloc 0x00800 Mnemonic Hex Corresponding Def Description all 0x00001 _STRACE ALL All strace messages flush 0x00002 _STRACE_FLUSH Flush output buffer after each messag inherit 0x00004 STRACE INHERIT Children inherit mask from parent uhoh 0x00008 _STRACE_UH
4. Nr include lt windows h gt char glpszText 1024 RESULT CALLBACK WndProc HWND UINT WPARAM LPARAM int APIENTRY WinMain HINSTANCE hInstance HINSTANCE hPrevInstance LPSTR lpCmdLine int nCmdShow sprintf glpszText Hello World nGetCommandLine s n WinMain lpCmdLine s n lpCmdLine GetCommandLine WNDCLASSEX wcex cbSiz style sizeof wcex CS_HREDRAW CS_VREDRAW lpfnWndProc WndProc wcex cbClsExtra 0 cbWndExtra 0 wcex Wcex wcex Wcex wcex hInstance hInstance LoadIcon NULL IDI APPLICATION LoadCursor NULL IDC_ARROW HBRUSH COLOR_WINDOW 1 NULL HEL wcex hlcon wcex hCursor wcex hbrBackground wcex lpszMenuName Wcex lpszClassName Os NULL wcex hIconSm if RegisterClassEx amp wcex return FALSE HWND hWnd hWnd CreateWindow HELLO Hello WS OVERLAPPEDWINDOW CW USEDEFAULT CW USEDEFAULT CW USEDEFAULT CW USEDEFAULT NULL NULL if hWnd hInstance 72 NULL Chapter 4 Programming with Cygwin return FALSE ShowWindow hWnd nCmdShow Updat eWindow hWnd MSG msg while GetMessage amp msg NULL 0 0 TranslateMessage amp msg DispatchMessage amp msg return msg wParam LRESULT CALLBACK WndProc HWND hWnd UINT message WPA
5. e cleanup threads num Number of threads started to perform cleanup tasks Default is 2 Configuration file option kern srv cleanup threads r request threads num Number of threads started to serve application requests Default is 10 The c and r options can be used to play with Cygserver s performance under heavy load conditions or on slow machines Configuration file option kern srv request threads d debug Log debug messages to stderr These will clutter your stderr output with a lot of information typically only useful to developers e stderr Force logging to stderr This is the default if stderr is connected to a tty Otherwise the default is logging to the system log By using the e E y Y options or the appropriate settings in the configuration file you can explicitely set the logging output as you like even to both stderr and syslog Configuration file option kern log stderr 42 Chapter 3 Using Cygwin E no stderr Don t log to stderr Configuration file option kern log stderr y Syslog Force logging to the system log This is the default if stderr is not connected to a tty e g redirected to a file Note that on 9x Me systems the syslog is faked by a file C CYGWIN_SYSLOG TXT Configuration file option kern log syslog Y no syslog Don t log to syslog Configuration file option kern log syslog Ly log level lt level gt Set the ver
6. A device name may be a UNC path server_name printer_name a reserved DOS device name prn 1pt 1 or a local port name that is mapped to a printer share Note that forward slashes may be used in a UNC path server name printer name which is helpful when using Ipr from a shell that uses the backslash as an escape character Ipr sends raw data to the printer no formatting is done Many but not all printers accept plain text as input If your printer supports PostScript packages such as a2ps and enscript can prepare text files for printing The ghostscript package also provides some translation from PostScript to various native printer languages Additionally a native Windows application for printing PostScript gsprint is available from the Ghostscript website http www cs wisc edu ghost 70 Chapter 4 Programming with Cygwin 4 1 Using GCC with Cygwin 4 1 1 Console Mode Applications Use gcc to compile just like under UNIX Refer to the GCC User s Guide for information on standard usage and options Here s a simple example Example 4 1 Building Hello World with GCC C gt gcc hello c o hello exe C gt hello exe Hello World C gt 4 1 2 GUI Mode Applications Cygwin allows you to build programs with full access to the standard Windows 32 bit API including the GUI functions as defined in any Microsoft or off the shelf publication However the process of building those applications is slightly
7. dev conout Windows CONOUTS dev clipboard the Windows clipboard currently text only and dev windows the Windows message queue Windows NT W2K XP additionally support raw devices like floppies disks partitions and tapes These are accessed from Cygwin applications using POSIX device names which are supported in two different ways Up to Cygwin 1 3 3 the only way to access those devices was to mount the Win32 device names to a POSIX device name but this usage is discouraged since Cygwin 1 3 4 and only kept for backward compatibility Beginning with Cygwin 1 3 4 raw devices are accessible by Cygwin processes using fixed POSIX device names These fixed POSIX device names are generated using a direct conversion from the POSIX namespace to the internal NT namespace E g the first harddisk is the NT internal device device harddiskO partitionO or the first partition on the third harddisk is device harddisk2 partition 1 The first floppy in the system is device floppy0 the first CD ROM is device cdrom0 and the first tape drive is device tape0 The new fixed POSIX names are mapped to NT internal devices as follows dev st0 device tape0 rewind dev nst0 device tape0 no rewind dev st1 device tapel dev fd0 device floppy0 dev fdl device floppyl dev scd0 device cdrom0 dev scdi device cdroml dev sr0 device cdromO 36 Chapter 3 Using Cygwin dev srl device cdroml dev sda device harddisk0 partiti
8. multi string set type to REG MULTI SZ s string set type to REG SZ Options for set and unset Actions K lt c gt key separator lt c gt set key separator to c instead of Other Options h help output usage information and exit q quiet no error output just nonzero return if KEY VALUE missing V verbos verbose output including VALUE contents when applicable V version output version information and exit KEY is in the format host NprefixNKEYNKEYNVALUE where host is optional remote host in eit root HKCR H config HKCC user HKCU machine HKLM users HKU er hostname or hostname format and prefix is any of EY CLASSES ROOT local only EY CURRENT CONFIG local only EY CURRENT USER local only EY LOCAL MACHINE EY USERS n K HK HK HK HK You can use forward slash as a separator instead of backslash in that case backslash is treated as escape character Example regtool exe get user software Microsoft Clock iFormat The regtool program allows shell scripts to access and modify the Windows registry Note that modifying the Windows registry is dangerous and carelessness here can result in an unusable system Be careful The v option means verbose For most commands this causes additional or lengthier messages to be printed Conversely the q option supresses er
9. Aucun in French etc in domains it is named Domain Users Unfortunately the group None is never shown in the user admin tool outside of domains This is very confusing but this seems to have no negative consequences To work correctly ntsec depends on the files etc passwd and etc group In Cygwin release 1 0 the names and the IDs must correspond to the appropriate NT IDs The IDs used in Cygwin are the RID of the NT SID as mentioned earlier A SID of e g the user corinna on my NT workstation S 1 5 21 165875785 1005667432 441284377 1000 Note the last number It s the RID 1000 Cygwin s UID Unfortunately workstations and servers outside of domains are not able to set primary groups In these cases where there is no correlation of users to primary groups NT returns 513 None as primary group regardless of the membership to existing local groups When using mkpasswd l g on such systems you have to change the primary group by hand if None as primary group is not what you want and I m sure it s not what you want 19 Chapter 2 Setting Up Cygwin Look at the following examples which were parts of my files before storing SIDs in etc passwd and etc group had been introduced See next chapter for details With the exception of my personal user entry all entries are well known entries Example 2 1 etc passwd everyone 0 0 system 18 18 administrator 500 544 home root b
10. Chapter 2 Setting Up Cygwin seteuid own uid Ccygwin set impersonation token user2 token seteuid user2 uid seteuid own uid Ccygwin set impersonation token userl token seteuid userl uid eto 2 4 8 Switching User Context Since Cygwin release 1 3 3 applications that are members of the Administrators group and have the Create a token object Replace a process level token and Increase Quota user rights can switch user context without giving a password by just calling the usual setuid seteuid setgid and setegid functions On NT and Windows 2000 the SYSTEM user has these privileges and can run services such as sshd However on Windows 2003 SYSTEM lacks the Create a token object right so it is necessary to create a special user with all the necessary rights as well as Logon as a service to run such services For security reasons this user should be denied the rights to logon interactively or over the network AII this is done by configuration scripts such as ssh host config An important restriction of this method is that a process started without a password cannot access network shares which require authentication This also applies to subprocesses which switched user context without a password Therefore when using ssh or rsh without a password it is typically not possible to access network drives 2 4 9 Special values of user and group ids If the current user is not present in et c passwd that user
11. I suboptions memflags CHARACTERISTICS num 79 Chapter 4 Programming with Cygwin LANGUAG VERSION num num AN DA num memflags are MOVEABLE FIXED PURE IMPURE PRELOAD LOADONCALL DISCARDABLE 60
12. netwrk svc S 1 5 20 20 none 1 5 21 1844237615 436374069 1060284298 513 513 bckup_op S 1 5 32 551 551 guests S 1 5 32 546 546 pwrusers S 1 5 32 547 547 replicator S 1 5 32 552 552 users 1 5 32 545 545 If you want to do similar changes to your files please do that only if you re feeling comfortably with the concepts Otherwise don t be surprised if some stuff doesn t work anymore If you screwed up things revert to files created by mkpasswd and mkgroup Especially don t change the UID or the name of user SYSTEM Even if that works mostly some Cygwin applications running as local service under that account could suddenly start behaving strangely 2 4 5 The mapping leak Now its time to point out the leak in the NT permissions The official documentation explains in short the following access allow ACEs are accumulated regarding to the group membership of the caller 22 Chapter 2 Setting Up Cygwin The order of ACEs is important The system reads them in sequence until either any needed right is denied or all needed rights are granted Later ACEs are then not taken into account All access denied ACEs _should_ precede any access allowed ACE Note that the last rule is a preference not a law NT will correctly deal with the ACL regardless of the sequence order The second rule is not modified to get the ACEs in the preferred order Unfortunately the security tab of the NT4 explorer is completely un
13. signal masks and other similar process specific information The DLL is implemented using the Win32 API which allows it to run on all Win32 hosts Because processes run under the standard Win32 subsystem they can access both the UNIX compatibility calls provided by Cygwin as well as any of the Win32 API calls This gives the programmer complete flexibility in designing the structure of their program in terms of the APIs used For example they could write a Win32 specific GUI using Win32 API calls on top of a UNIX back end that uses Cygwin Early on in the development process we made the important design decision that it would not be necessary to strictly adhere to existing UNIX standards like POSIX 1 if it was not possible or if it would significantly diminish the usability of the tools on the Win32 platform In many cases an environment variable can be set to override the default behavior and force standards compliance 1 6 2 Supporting both Windows NT and 9x While Windows 95 and Windows 98 are similar enough to each other that we can safely ignore the distinction when implementing Cygwin Windows NT is an extremely different operating system For this reason whenever the DLL is loaded the library checks which operating system is active so that it can act accordingly In some cases the Win32 API is only different for historical reasons In this situation the same basic functionality is available under Windows 9x and NT but the method u
14. 3 2 4 Binary or text occa E aO Sa RR DER TUO gm RP 34 3 2 5 Programming ss teo ie Des nt te et rere np eie 34 3 3 File p rmi ssion S i e at ia He cac e Ide Pbi ien A etes 35 3 44 Special filenames 5 i eee RPROW ORI reote PIU ei p ge iita 35 3 4 1 DOSdev1688 eats eb tei i e aie laa 35 3 42 POSIX devices iie cen eie eme denter eee 35 SAB The eXe extensIOD revien eoe ec o e Eee NO E a Mort Ero Eee ced 37 3 4 4 The proc filesystem smith int OO e ee eee 38 3 45 The pathnames eR RUE RUE RE RR nee eed 38 3 5 The CYGWIN environment variable sis 39 3 6 CY BSELVER 5c citta eo Hei e ea EE IHRE A Ee ate ir iio irent 41 3 6 1 What 1s Cygserver is teen dee nt OH RO RR RO Ole 41 3 6 2 Cygserver command line options ss 41 3 6 3 How to start Cy SS rver sce eese deeem ene ete vede 44 3 6 4 How to use the Cygserver Services 44 3 6 5 The Cygserver configuration file nennen ene 45 3 7 Cy Ss win Utilities rd eR REO SERE EUR E QU be d 45 Bef ls Cy Che CK ties note un pH endete eis 46 3272 Cygpath ice HUS e Nees a edie ies ee tei alee 47 3 7 3 dumper oa epe e oO UHR P De DO D i 49 3 34 getfacl ui ebat ebetui ui de EE 49 3775 kall z ias cost eoo des ree desta em 50 3 7 6 mkPproup inc etre e se eee en IRI Stee a ERR 52 877 1 mkpasswd ito seen e PUDE I et bee 53 3 78 AMOUNE sto ees eee
15. Files are considered to be executable if the filename ends with bat com or exe or if its content starts with Consequently chmod can only affect the w mode it silently ignores actions involving the other modes This means that Is l needs to open and read files It can thus be relatively slow Under NT file permissions default to the same behavior as Windows 9x but there is optional functionality in Cygwin that can make file systems behave more like on UNIX systems This is turned on by adding the ntea option to the CYGWIN environment variable When the ntea feature is activated Cygwin will start with basic permissions as determined above but can store POSIX file permissions in NT Extended Attributes This feature works quite well on NTFS partitions because the attributes can be stored sensibly inside the normal NTFS filesystem structure However on a FAT partition NT stores extended attributes in a flat file at the root of the partition called EA DATA SF This file can grow to extremely large sizes if you have a large number of files on the partition in question slowing the system to a crawl In addition the EA DATA SF file can only be deleted outside of Windows because of its in use status For these reasons the use of NT Extended Attributes is off by default in Cygwin Finally note that specifying ntea in CYGWIN has no effect under Windows 9x Under NT the test w filename is only true if filename is writable
16. Usage ps aefls u UID Report process status 2aj all show processes of all users veryon show processes of all users f fudd show process uids ppids h help output usage information and exit l long show process uids ppids pgids winpids S summary show process summary u user list processes owned by UID V version output version information and exit W windows show windows as well as cygwin processes With no options ps outputs the long format by default The ps program gives the status of all the Cygwin processes running on the system ps process status Due to the limitations of simulating a POSIX environment under Windows there is little information to give The PID column is the process ID you need to give to the kill command The PPID is the parent process ID and PGID is the process group ID The WINPID column is the process ID displayed by NT s Task Manager program The TTY column gives which pseudo terminal a process is running on or a for services The UID column shows which user owns each process STIME is the time the process was started and COMMAND gives the name of the program running Listings may also have a status flag in column zero s means stopped or suspended in other words in the background 1 means waiting for input or interactive foreground and o means waiting to output By default ps will only show processes owned by the current user With either the
17. a Cygwin process first starts Set it to point to your home directory before launching bash The TERM environment variable specifies your terminal type It is automatically set to cygwin if you have not set it to something else The LD_LIBRARY_PATH environment variable is used by the Cygwin function dlopen as a list of directories to search for dll files to load This environment variable is converted from Windows format to UNIX format when a Cygwin process first starts Most Cygwin applications do not make use of the dlopen call and do not need this variable 2 3 Changing Cygwin s Maximum Memory By default no Cygwin program can allocate more than 384 MB of memory program data You should not need to change this default in most circumstances However if you need to use more real or virtual memory in your machine you may add an entry in the either the HKEY LOCAL MACHINE to change the limit for all users or HKEY CURRENT USER for just the current user section of the registry Add the DWORD value heap chunk in mb and set it to the desired memory limit in decimal MB It is preferred to do this in Cygwin using the regtool program included in the Cygwin package For more information about regtool or the other Cygwin utilities see Section 3 7 or use each the help option of each util You should always be careful when using regtool since damaging your system registry can result in an unusable system This exa
18. across the board e g chmod w filename 3 4 Special filenames 3 4 1 DOS devices Windows filenames invalid under Windows are also invalid under Cygwin This means that base filenames such as AUX COM1 LPT1 or PRN to name a few cannot be used in a regular Cygwin Windows or POSIX path even with an extension prn txt However the special names can be used as filename extensions ile aux You can use the special names as you would under DOS for example you can print on your default printer with the command cat filename PRN make sure to end with a Form Feed 35 Chapter 3 Using Cygwin 3 4 2 POSIX devices There is no need to create a POSIX dev directory as Cygwin automatically simulates it internally These devices cannot be seen with the command Is dev although commands such as Is dev tty work fine If you want to be able to see all devices in dev you can use Igor Pechtchanski s create devices sh http cygwin com ml cygwin 2004 03 txt00028 txt script Cygwin supports the following devices commonly found on POSIX systems dev dsp dev null dev zero dev console dev tty dev ttym dev ttyX dev ttySX dev pipe dev port dev ptmx dev mem dev random and dev urandom Some other POSIX devices such as dev kmem are planned for development Cygwin also has several Windows specific devices dev comx the serial ports starting with com1 which is the same as tt yS0 dev conin Windows CONINS
19. domain account d domain print global group information from current domain if no domains specified o id offset offset change the default offset 10000 added to gids in domain accounts S no sids don t print SIDs in pwd field this affects ntsec u users print user list in gr mem field g group groupname only return information for the specified group n h help print this message v version print version information and exit One of l or d must be given on NT W2K The mkgroup program can be used to help configure your Windows system to be more UNIX like by creating an initial etc group Its use is essential on the NT series Windows NT 2000 and XP to include Windows security information It can also be used on the Win9x series Windows 95 98 and Me to create a file with the correct format To initially set up your machine if you are a local user you d do something like this Example 3 6 Setting up the groups file for local accounts mkdir etc mkgroup 1 gt etc group Note that this information is static If you change the group information in your system you ll need to regenerate the group file for it to have the new information The d and 1 options allow you to specify where the information comes from the local machine or the domain default or given or both With the a option the program contacts the Domain Controller which my be unreachable or have restricted access An entry f
20. either forward or back slashes as the directory delimiter Paths coming into the DLL are translated from Win32 to POSIX as needed As a result the library believes that the file system is a POSIX compliant one translating paths back to Win32 paths whenever it calls a Win32 API function UNC pathnames starting with two slashes are supported The layout of this POSIX view of the Windows file system space is stored in the Windows registry While the slash directory points to the system partition by default this is easy to change with the Cygwin mount utility In addition to selecting the slash partition it allows mounting arbitrary Win32 paths into the POSIX file system space Many people use the utility to mount each drive letter under the slash partition e g C to c D to d etc The library exports several Cygwin specific functions that can be used by external programs to convert a path or path list from Win32 to POSIX or vice versa Shell scripts and Makefiles cannot call these functions directly Instead they can do the same path translations by executing the cygpath utility program that we provide with Cygwin Win32 file systems are case preserving but case insensitive Cygwin does not currently support case Chapter 1 Cygwin Overview distinction because in practice few UNIX programs actually rely on it While we could mangle file names to support case distinction this would add unnecessary overhead to the library and m
21. etit suu ee e edite Mn mi Een 20 2 3 Jetc passwd en notes DM eH Ai 21 pr Siero Re 21 2 5 fetc passwd ee bed IR oe AAG Se EA a SAG SA Rein 22 2 6 Jete group cic osi ttt RE tiU eH Bee uned ne dees Uto tpi or rene es 22 3 1 Displaying the current set of mount points ener eerte nennen enne ene 31 3 2 Using pathname ss 23 eoe ete etm e ted de e Nb te ett edens 38 3 3 Example cygcheck usage eene nennen nenne S EE enr entente enn ennen rene 46 3 4 Example cygpatlhi usii eenen rS Les PR eleme it e re est eei ds 48 3 5 Using the kill command Renee A tees 51 3 6 Setting up the groups file for local accounts ss 52 3 7 Setting up the passwd file for local accounts ss 53 3 8 Using an alternate home root oic gc e ne E Ree e i ERO Ete Eu ds 54 3 9 Displaying the current set of mount points eene entren enne ene 55 3 10 Adding MOUNE points trot de rte tee ed te e t tede eti neces 55 3 11 Changing the default prefix ss 56 4 1 Building Hello World with GO eiit Ge eerte bte Rnb ten nt 71 4 2 Compiling with g eee etse eere ecrire tdt ree tenete ig scape ente e Re 74 posl dup 74 4 4 Debugging with command line arguments ss 74 vi Chapter 1 Cygwin Overview 1 1 What is it Cygwin is a Linux like environment for Windows It consists of a DLL cygwin1 d11 which acts as an emulation layer providing su
22. exist once in the user table and once in the global system wide table Attempts to replace the mount will fail with a busy error The force flag causes the old mount to be silently replaced with the new one It will also silence warnings about the non existence of directories at the Win32 path location 55 Chapter 3 Using Cygwin The b flag is used to instruct Cygwin to treat binary and text files in the same manner by default Binary mode mounts are marked as binmode in the Flags column of mount output By default mounts are in text mode textmode in the Flags column Normally files ending in certain extensions exe com bat cmd are assumed to be executable Files whose first two characters begin with are also considered to be executable The x flag is used to instruct Cygwin that the mounted file is executable If the x flag is used with a directory then all files in the directory are executable This option allows other files to be marked as executable and avoids the overhead of opening each file to check for a The x option is very similar to x but also prevents Cygwin from setting up commands and environment variables for a normal Windows program adding another small performance gain The opposite of these flags is the E flag which means that no files should be marked as executable Note that there is currently a hard coded limit of 30 mount points The m option causes the mount utility to
23. is waiting on and blocks on another mutex This is the signal for the parent to copy its stack and heap into the child after which it releases the mutex the child is waiting on and returns from the fork call Finally the child wakes from blocking on the last mutex recreates any memory mapped areas passed to it via the shared area and returns from fork itself While we have some ideas as to how to speed up our fork implementation by reducing the number of context switches between the parent and child process fork will almost certainly always be inefficient under Win32 Fortunately in most circumstances the spawn family of calls provided by Cygwin can be substituted for a fork exec pair with only a little effort These calls map cleanly on top of the Win32 API As a result they are much more efficient Changing the compiler s driver program to call spawn instead of fork was a trivial change and increased compilation speeds by twenty to thirty percent in our tests However spawn and exec present their own set of difficulties Because there is no way to do an actual exec under Win32 Cygwin has to invent its own Process IDs PIDs As a result when a process performs multiple exec calls there will be multiple Windows PIDs associated with a single Cygwin PID In some cases stubs of each of these Win32 processes may linger waiting for their exec d Cygwin process to exit 1 6 8 Signals When a Cygwin process starts the library starts a secondary
24. of these regtool tries to guess the type based on the value you give If it looks like a number it s a DWORD If it starts with a percent it s an expanding string If you give multiple values it s a multi string Else it s a regular string The unset action removes a value from a key By default the last V or is assumed to be the separator between the key and the value You can use the K option to provide an alternate key value separator character 3 7 12 setfacl Usage setfacl r f ACL FILE s acl entries FILE setfacl r d acl entries m acl entries FILE Modify file and directory access control lists ACLs d delet delete one or more specified ACL entries f file set ACL entries for FILE to ACL entries read from a ACL FILE m modify modify one or more specified ACL entries ary replac replace mask entry with maximum permissions needed for the file group class s substitute substitute specified ACL entries for the ACL of FILE h help output usage information and exit Vv version output version information and exit At least one of d Ly NE S must be specified For each file given as parameter setfacl will either replace its complete ACL s or it will add modify or delete ACL entries For more information on Cygwin and Windows ACLs see see Section 2 4 in the Cygwin User s Guide Acl entries are one or more comma separat
25. programs The usual purpose is to end a running program from some other window when C won t work but you can also send program specified signals such as SIGUSRI to trigger actions within the program like enabling debugging or re opening log files Each program defines the signals they understand You may need to specify the full path to use kill from within some shells including bash the default Cygwin shell This is because bash defines a kill builtin function see the bash man page under BUILTIN COMMANDS for more information To make sure you are using the Cygwin version try bin kill version 50 Chapter 3 Using Cygwin which should give the Cygwin kill version number and copyright information Unless you specific the f option the pid values used by kill are the Cygwin pids not the Windows pids To get a list of running programs and their Cygwin pids use the Cygwin ps program ps W will display all windows pids The kill l option prints the name of the given signal or a list of all signal names if no signal is given To send a specific signal use the signN option either with a signal number or a signal name minus the SIG part like these examples Example 3 5 Using the kill command kill 123 kill 1 123 kill HUP 123 kill f 123 Here is a list of available signals their numbers and some commentary on them from the file sys signal h which should be considered the official source of this
26. s user id is set to a special value of 400 The user name for the current user will always be shown correctly If another user or a Windows group treated as a user is not present in etc passwd the user id of that user will have a special value of 1 which would be shown by Is as 65535 The user name shown in this case will be 22222 If the current user is not present in etc passwa that user s login group id is set to a special value of 401 If another user is not present in etc passwad that user s login group id is set to a special value of If the user is present in et c passwd but that user s group is not in etc group and is not the login group of that user the group id is set to a special value of 1 The name of this group id 1 will be shown as 22222 2 In releases of Cygwin before 1 3 20 the group id 401 had a group name None 27 Chapter 2 Setting Up Cygwin Since Cygwin release 1 3 20 the group id 401 is shown as mkpasswd indicating the command that should be run to alleviate the situation Also since Cygwin release 1 3 20 if the current user is present in etc passwd but that user s login group is not present in etc group the group name will be shown as mkgroup again indicating the appropriate command To summarize If the current user doesn t show up in etc passwd it s group will be named mkpasswd Otherwise if the login group of the current user isn t in etc group it will be
27. they are installed The cache must not be the same folder as the Cygwin root Within the cache a separate directory is created for each Cygwin mirror which allows setup exe to use multiple mirrors and custom packages After installing Cygwin the cache is no longer necessary but you may want to retain the packages as backups for installing Cygwin to another system or in case you need to reinstall a package 2 1 4 Connection Method The Direct Connection method of downloading will directly download the packages while the IE5 method will leverage your IES cache for performance If your organisation uses a proxy server or auto configuration scripts the IE5 method also uses these settings If you have a proxy server you can manually type it into the Use Proxy section Unfortunately setup exe does not currently support password authorization for proxy servers 2 1 5 Choosing Mirrors Since there is no way of knowing from where you will be downloading Cygwin you need to choose at least one mirror site Cygwin mirrors are geographically distributed around the world check the list at http cygwin com mirrors html to find one near you You can select multiple mirrors by holding down 11 Chapter 2 Setting Up Cygwin CTRL and clicking on each one If you have the URL of an unlisted mirror for example if your organization has an internal Cygwin mirror you can add it 2 1 6 Choosing Packages For each selected mirror site setup exe dow
28. things For example the first part of the report reports the amount of time spent in each function like this 64 Chapter 3 Using Cygwin Each sample counts as 0 01 seconds cumulative self self total time seconds seconds calls ms call ms call name 10 02 231 22 72 43 46 1574 57 1574 57 strcspn 7 95 288 70 57 48 130 442 15 442 15 strncasematch The seconds columns are really CPU opcodes 1 100 second per opcode So 231 22 above means 23 122 opcodes The ms call values are 10x too big 1574 57 means 157 457 opcodes per call Similar adjustments need to be made for the self and children columns in the second part of the report OK so now we ve got a huge report that took a long time to generate and we ve identified a spot we want to work on optimizing Let s say it s the time function We can use SSP to selectively profile this function by using OutputDebugString to control SSP from within the program Here s a sample program include lt windows h gt main time_t t OutputDebugString ssp on time amp t OutputDebugString ssp off Then add the d option to ssp to default to disabling profiling The program will run at full speed until the first OutputDebugString then step until the second You can then use gprof as usual to see the performance profile for just that portion of the program s execution There are many options to ssp Since step profiling makes your program run about 1 000 time
29. thread for use in signal handling This Chapter 1 Cygwin Overview thread waits for Windows events used to pass signals to the process When a process notices it has a signal it scans its signal bitmask and handles the signal in the appropriate fashion Several complications in the implementation arise from the fact that the signal handler operates in the same address space as the executing program The immediate consequence is that Cygwin system functions are interruptible unless special care is taken to avoid this We go to some lengths to prevent the sig send function that sends signals from being interrupted In the case of a process sending a signal to another process we place a mutex around sig send such that sig send will not be interrupted until it has completely finished sending the signal In the case of a process sending itself a signal we use a separate semaphore event pair instead of the mutex sig send starts by resetting the event and incrementing the semaphore that flags the signal handler to process the signal After the signal is processed the signal handler signals the event that it is done This process keeps intraprocess signals synchronous as required by POSIX Most standard UNIX signals are provided Job control works as expected in shells that support it 1 6 9 Sockets Socket related calls in Cygwin simply call the functions by the same name in Winsock Microsoft s implementation of Berkeley sockets Only a few
30. to support the system file attribute Many do not do so by default the Unix Samba server does not by default for example 3 2 Text and Binary modes 3 2 1 The Issue On a UNIX system when an application reads from a file it gets exactly what s in the file on disk and the converse is true for writing The situation is different in the DOS Windows world where a file can be opened in one of two modes binary or text In the binary mode the system behaves exactly as in UNIX However on writing in text mode a NL Wn J is transformed into the sequence CR V M NL This can wreak havoc with the seek fseek calls since the number of bytes actually in the file may differ from that seen by the application The mode can be specified explicitly as explained in the Programming section below In an ideal DOS Windows world all programs using lines as records such as bash make sed would open files and change the mode of their standard input and output as text All other programs such as cat cmp tr would use binary mode In practice with Cygwin programs that deal explicitly with object files specify binary mode this is the case of od which is helpful to diagnose CR problems Most other programs such as cat cmp tr use the default mode 3 2 2 The default Cygwin behavior The Cygwin system gives us some flexibility in deciding how files are to be opened when the mode is not specified explicitly The rules are evolving this
31. you a warning most everything will work properly when you refer to the mount point explicitly Some strange effects can occur however For example if your current working directory is dir say and dir mtpt is a mount point then mtpt will not show up in an Is or echo command and find will not find mtpt 3 7 9 passwd Usage passwd OPTION USER Change USER s password or password attributes User operations L L0ck lock USER s account u unlock unlock USER s account SC cannot chang USER can t change password C can chang USER can change password e never expires USER s password never expires E expires USER s password expires according to system s password aging rule p pwd not required no password required for USER P pwd required password is required for USER System operations i inactive NUM set NUM of days before inactive accounts are disabled inactive accounts are those with expired passwords n minage DAYS set system minimum password age to DAYS days x maxage DAYS Set system maximum password age to DAYS days L length LEN set system minimum password length to LEN 57 Chapter 3 Using Cygwin Other options S status display password status for USER locked expired etc plus global system password settings h help output usage information and exit v version output version information and exit
32. AC ANGUAG ERSION TYLE number number QA FE trol O3STATE params U U UT ED HE Qwurrracdcrta Q o LE FOO NOT FOO 12 name RISTICS number number number OCHECKBOX params IT params Q KBOX params BOBOX params CONTROL name CONTROL name CTE DEF XT params EDI ITEXT params GRO UPBOX params HED ICO ICO ICO IT params N name id N name id N name id IED LIS IT params TBOX params IE PUS PUS RAD XT params HBOX params HBUTTON params ORADIOBUTTON params id class id class PUSHBUTTON params name weight italic Chapter 4 Programming with Cygwin style x y w h exstyle data style x y w h exstyle helpid X y data style exstyle data style xstyle helpid data XY B r Xi VW Ar IOBUTTON params RTE XT params SCROLLBAR params STATE3 params USERBUTTON string id x y w h par n n n da id ams ame id x y w h data ame id x y w h style style exstyle exstyle data ame id x y w h style xstyl ta is optional BEG string number FONT memflags filename memflags defaults to MOVEAB id LAN E DISCARDABLI ICON memflags filename memflags defaults to MOVEAB GUAGE num num id MENU optio
33. Cygwin User s Guide Cygwin User s Guide Copyright 1998 1999 2000 2001 2002 2003 Red Hat Inc Table of Contents nnL 1 IT What s it Anei ane gui is ee ni a Donne ip e BP pes 1 1 2 Quick Start Guide for those more experienced with Windows 1 1 3 Quick Start Guide for those more experienced with UNIX 2 1 4 Are the Cygwinit ols free SOFtWAate aote tiene rediere cd d eee e eee 2 1 5 A brief history of the Cygwin project ses 3 1 6 Highlights of Cygwin Functionality ss 3 1 6 T Introduction eoe ei eei ee 3 1 6 2 Supporting both Windows NT and 9x ss 4 1 6 3 Permissions and Security ss 4 1 6 4 File ACCESS ee en ooh e re tei bete das ne ne et tis AU 5 1 6 5 Text Mode vs Binary Mode ss 6 L626 ANSEG Library se Me enr reet PEOR Pete t P ex ESS 6 1 6 7 Process Creation uites GS ehh RARE TR RAT MIE LA 7 Ia 7 16 9 Sockets ence edu eue TER ees 8 1 60 10 Sel CD s so et t editt e tite t dp dou pia den hs 8 2 Setting Up ebrii 10 2 1 Internet Setup lines RSR Rs enr M omoi ier edits 10 2 1 1 Download Source sn eed eei e ce t EE ee a bine cete ei 10 2 1 2 Selecting an Install Directory cnni i het perrita 11 2 1 3 Local Package Directory uoce teet cette erret rendered 11 2 1 4 Connection Method oie genie eene Dun ioter eerte 11 2 1 5 Choosing Mirrors i ecc oec eret ete oo Oc e oi i in nt 11 2 1 6 Choosing Packages een
34. Directory Unfortunately setup exe does not yet support unattended installs Though this provides some basic mirroring functionality if you are managing a wide Cygwin installation to keep up to date we recommend using a mirroring tool such as wget A helpful user on the 10 Chapter 2 Setting Up Cygwin Cygwin mailing list created a simple demonstration script to accomplish this search the list for mkcygwget for ideas 2 1 2 Selecting an Install Directory The Root Directory for Cygwin default C Ncygwin will become within your Cygwin installation You must have write access to the parent directory and any ACLs on the parent directory will determine access to installed files The Install For options of All Users or Just Me should always be left on the default A11 Users unless you do not have write access to HKEY LOCAL MACHINE in the registry or the All Users Start Menu This is true even if you are the only user planning to use Cygwin on the machine Selecting Just Me will cause problems for programs such as crond and sshd If you do not have the necessary permissions but still want to use these programs consult the Cygwin mailing list archives about others experiences The Default Text File Type should be left on Unix that is n unless you have a very good reason to switch it to DOS that is Nx n 2 1 3 Local Package Directory The Local Package Directory is the cache where setup exe stores the packages before
35. I to access the file system their access can be restricted as it is intended This includes not only POSIX paths but Win32 paths containing drive letter and or backslashes and CIFS paths server share or server share as well 1 6 5 Text Mode vs Binary Mode Interoperability with other Win32 programs such as text editors was critical to the success of the port of the development tools Most Red Hat customers upgrading from the older DOS hosted toolchains expected the new Win32 hosted ones to continue to work with their old development sources Unfortunately UNIX and Win32 use different end of line terminators in text files Consequently carriage return newlines have to be translated on the fly by Cygwin into a single newline when reading in text mode This solution addresses the compatibility requirement at the expense of violating the POSIX standard that states that text and binary mode will be identical Consequently processes that attempt to Iseek through text files can no longer rely on the number of bytes read as an accurate indicator of position in the file For this reason the CYGWIN environment variable can be set to override this behavior 1 6 6 ANSI C Library We chose to include Red Hat s own existing ANSI C library newlib as part of the library rather than Chapter 1 Cygwin Overview write all of the lib C and math calls from scratch Newlib is a BSD derived ANSI C library previously only used by cross compilers for
36. OH Unusual or weird phenomenon syscall 0x00010 STRACE SYSCALL System calls startup 0x00020 STRACE STARTUP argc envp printout at startup debug 0x00040 STRACE DEBUG Info to help debugging paranoid 0x00080 STRACE PARANOID Paranoid info termios 0x00100 STRACE TERMIOS Info for debugging termios stuff select 0x00200 STRACE SELECT Info on ugly select internals 66 Chapter 3 Using Cygwin wm 0x00400 sigp 0x00800 minimal 0x01000 exitdump 0x04000 system 0x08000 RACE WM Trace Windows msgs enable strace wm RACE SIGP Trace signal and process handling RACE MINIMAL Very minimal strace output RACE EXITDUMP Dump strace cache on exit Pade e NNNNNNN UM RACE SYSTEM Serious error goes to console and log nomutex 0x10000 STRACE NOMUTEX Don t use mutex for synchronization malloc 0x20000 STRACE MALLOC Trace malloc calls thread 0x40000 STRACE THREAD hread locking calls The strace program executes a program and optionally the children of the program reporting any Cygwin DLL output from the program s to stdout or to a file with the o option With the w option you can start an strace session in a new window for example strace o tracing output w sh c while true do echo tracing done amp This is particularly useful for strace sessions that take a long time to complete Note that strace is a standalone W
37. RAM wParam LPARAM lParam PAINTSTRUCT ps HDC hdc switch message case WM_PAINT hdc BeginPaint hWnd amp ps RECT rt GetClientRect hWnd amp rt DrawText hdc glpszText strlen glpszText amp rt DT TOP DT LEFT EndPaint hWnd amp ps break case WM_DESTROY PostQuitMessage 0 break default return DefWindowProc hWnd message wParam lParam return 0 4 2 Debugging Cygwin Programs When your program doesn t work right it usually has a bug in it meaning there s something wrong with the program itself that is causing unexpected results or crashes Diagnosing these bugs and fixing them is made easy by special tools called debuggers In the case of Cygwin the debugger is GDB which stands for GNU DeBugger This tool lets you run your program in a controlled environment where you can investigate the state of your program while it is running or after it crashes Crashing programs sometimes create core files In Cygwin these are regular text files that cannot be used directly by GDB 73 Chapter 4 Programming with Cygwin Before you can debug your program you need to prepare your program for debugging What you need to do is add g to all the other flags you use when compiling your sources to objects Example 4 2 Compiling with g gcc g O2 c myapp c gcc g myapp c o myapp What this does is add extra information to the objects they get much bigg
38. X shell The compiler tools are the standard GNU compilers most people will have previously used under UNIX only ported to the Windows host Programmers wishing to port UNIX software to Windows NT or 9x will find that the Cygwin library provides an easy way to port many UNIX packages with only minimal source code changes 1 4 Are the Cygwin tools free software Yes Parts are GNU http www gnu org software gcc gas Id etc parts are covered by the standard X11 license http www x org Downloads terms html some of it is public domain some of it was written by Red Hat and placed under the GNU General Public License http www gnu org licenses gpl html GPL None of it is shareware You don t have to pay anyone to use it but you should be sure to read the copyright section of the FAQ for more information on how the GNU GPL may affect your use of these tools If you intend to port a proprietary application using the Cygwin library you may want the Cygwin proprietary use license For more information about the proprietary use license please go to http www redhat com software tools cy gwin http www redhat com software tools cygwin Customers of the native Win32 GNUPro should feel Chapter 1 Cygwin Overview free to submit bug reports and ask questions through the normal channels All other questions should be sent to the project mailing list lt cygwin cygwin com gt 1 5 A brief history of the Cygwin project Note A more c
39. a or e option all user s processes and system processes are listed There are historical UNIX reasons for the synonomous options which are functionally identical The f option outputs a full listing with usernames for UIDs The 1 option is the default display mode showing a long listing with all the above columns The other display option is s which outputs a shorter listing of just PID TTY STIME and COMMAND The u option allows you to show only processes owned by a specific user The w option causes ps show non Cygwin Windows processes as well as Cygwin processes The WINPID is also the PID and they can be killed with the Cygwin kill command s f option 3 7 11 regtool Usage regtool ex OPTION add check get list remove unset KEY View or edit the Win32 registry Actions add KEYNSUBKEY add new SUBKEY 59 Chapter 3 Using Cygwin check KEY exit 0 if KEY exists 1 if not get KEYNVALUE prints VALUE to stdout list KEY list SUBKEYs and VALUEs remove KEY remove KEY set KEYNVALUE data set VALUE unset KEY VALUE removes VALUE from KEY Options for list Action k keys print only KEYs i LSet print only VALUEs p postfix like ls p appends postfix to KEY names Options for set Action e expand string set type to REG EXPAND SZ i integer Set type to REG DWORD m
40. able to deal with access denied ACEs while the explorer of W2K rearranges the order of the ACEs before you can read them Thank God the sort order remains unchanged if one presses the Cancel button You still ask Where is the leak NT ACLs are unable to reflect each possible combination of POSIX permissions Example IW I XIW Ist try UserAllow 110 GroupAllow 101 OthersAllow 110 Hmm because of the accumulation of allow rights the user may execute because the group may execute 2st try UserDeny 001 GroupAllow 101 OthersAllow 110 Now the user may read and write but not execute Better No Unfortunately the group may write now because others may write 3rd try UserDeny 001 GroupDeny 010 GroupAllow 001 OthersAllow 110 Now the group may not write as intended but unfortunately the user may not write anymore either How should this problem be solved According to the official rules a UserAllow has to follow the GroupDeny but it s easy to see that this can never be solved that way 23 Chapter 2 Setting Up Cygwin The only chance UserDeny 001 UserAllow 010 GroupDeny 010 GroupAllow 001 OthersAllow 110 Again This works for both NT4 and W2K Only the GUIs aren t able to deal with that order 2 4 6 The ACL API For dealing with ACLs Cygwin now has the ACL API as it s implemented in newer versions of Solaris The new data structure for a single ACL entry ACE in NT terminology is defined i
41. ads a Windows resource file rc and converts it to a res or coff file The syntax and semantics of the input file are the same as for any other resource compiler so please refer to any publication describing the Windows resource format for details Also the windres program itself is fully documented in the Binutils manual Here s an example of using it in a project myapp exe myapp o myapp res gcc mwindows myapp o myapp res o Q myapp res myapp rc resource h windres lt O coff o Q What follows is a quick reference to the syntax windres supports id ACCELERATORS suboptions BEG TACH L2 QN 12 65 12 65 12 VIRTKEY ASCII NOINVERT SHIFT CONTROL ALT 65 12 VIRTKEY ASCII NOINVERT SHIFT CONTROL ALT 12 is an acc id END SHIFT CONTROL ALT require VIRTKEY id BITMAP memflags filename memflags defaults to MOVEABLE id CURSOR memflags filename memflags defaults to MOVEABLE DISCARDABL Ld id DIALOG memflags exstyle x y width height styles BEG controls END id DIALOGEX memflags exstyle x y width height styles BEG controls END id DIALOGEX memflags exstyle x y width height helpid styles BEG controls END memflags defaults to MOVEABLE xstyle may be EXSTYLE number styles CAPTION string 77 CLASS id STY EXS on FONT number FONT number ENU id HAR
42. ake it more difficult for non Cygwin applications to access those files Symbolic links are emulated by files containing a magic cookie followed by the path to which the link points They are marked with the System attribute so that only files with that attribute have to be read to determine whether or not the file is a symbolic link Hard links are fully supported under Windows NT on NTFS file systems On a FAT file system the call falls back to simply copying the file a strategy that works in many cases The inode number for a file is calculated by hashing its full Win32 path The inode number generated by the stat call always matches the one returned in d ino of the dirent structure It is worth noting that the number produced by this method is not guaranteed to be unique However we have not found this to be a significant problem because of the low probability of generating a duplicate inode number Chroot is supported since release 1 1 3 Note that chroot isn t supported native by Windows This implies some restrictions First of all the chroot call isn t a privileged call Each user may call it Second the chroot environment isn t safe against native windows processes If you want to support a chroot environment as for example by allowing an anonymous ftp with restricted access you ll have to care that only native Cygwin applications are accessible inside of the chroot environment Since that applications are only using the Cygwin POSIX AP
43. al Cygwin environment installed by simply clicking the Next button at each page The only exception to this is choosing a Cygwin mirror which you can choose by experimenting with those listed at http cygwin com mirrors html http cygwin com mirrors html For more details about each of page of the setup exe installation read on below Please note that this guide assumes that you have a basic understanding of Unix or a Unix like OS If you are new to Unix you will also want to make use of other resources http www google com search q new to unix 2 1 1 Download Source Cygwin uses packages to manage installing various software When the default Install from Internet option is chosen setup exe creates a local directory to store the packages before actually installing the contents Download from Internet performs only the first part storing the packages locally while Install from Local Directory performs only the second installing the contents of the packages The Download from Internet option is mainly for creating a base Cygwin package tree on one computer for installation on several machines with Install from Local Directory copy the entire local package tree to another machine with the directory tree intact For example you might create a C cache directory and place setup exe in it Run setup exe to Install from Internet or Download from Internet then copy the whole C cache to each machine and instead choose Install from Local
44. and exit W windir output Windows directory and exit The cygpath program is a utility that converts Windows native filenames to Cygwin POSIX style pathnames and vice versa It can be used when a Cygwin program needs to pass a file name to a native Windows program or expects to get a file name from a native Windows program Alternatively cygpath can output information about the location of important system directories in either format The u and w options indicate whether you want a conversion to UNIX POSIX format u or to Windows format w Use the a to get DOS style 8 3 file and path names The m option will output Windows style format but with forward slashes instead of backslashes This option is especially useful in shell scripts which use backslashes as an escape character In combination with the w option you can use the 1 and s options to use normal long or DOS style short form The a option is identical to w and s together Caveat The 1 option does not work if the check case parameter of CYGWIN is set to strict since Cygwin is not able to match any Windows short path in this mode The p option means that you want to convert a path style string rather than a single filename For example the PATH environment variable is semicolon delimited in Windows but colon delimited in UNIX By giving p you are instructing cygpath to convert between these formats The i option supresses the print out of the usage me
45. ariable using Windows command line interpreter syntax e g set CYGWIN server 44 Chapter 3 Using Cygwin If you don t set CYGWIN in the system environment but you re running other Cygwin services these services need to get that CYGWIN value by setting the environment using the appropriate cygrunsrv option e when installing the service Example installing a service foo cygrunsrv I foo p usr sbin foo e CYGWIN server 3 6 5 The Cygserver configuration file Cygserver has many options which allow to customize the server to your needs Customization is accomplished by editing the configuration file which is by default etc cygserver conf This file is read only once on startup of Cygserver There s no option to re read the file on runtime by say sending a signal to Cygserver The configuration file determines how Cygserver operates There are options which set the number of threads running in parallel options for setting how and what to log and options to set various maximum values for the IPC services The default configuration file delivered with Cygserver is installed to etc defaults etc The lusr bin cygserver config script copies it to etc giving you the option to overwrite an already existing file or to leave it alone Therefore the etc file is safe to be changed by you since it will not be overwritten by a later update installation The default configuration file contains many comments which describe
46. bosity level of the logging output Valid values are between 1 and 7 The default level is 6 which is relatively chatty If you set it to 1 you will get only messages which are printed under severe conditions which will result in stopping Cygserver itself Configuration file option kern log level m no sharedmem Don t start XSI IPC Shared Memory support If you don t need XSI IPC Shared Memory support you can switch it off here Configuration file option kern srv sharedmem q no msgqueues Don t start XSI IPC Message Queues Configuration file option kern srv msgqueues S no semaphores Don t start XSI IPC Semaphores Configuration file option kern srv semaphores eo S 8hutdown Shutdown a running daemon and exit Other methods are sending a SIGHUP to the Cygserver PID or if running as service under NT calling net stop cygserver or cygrunsrv E cygserver h help Output usage information and exit V version 43 Chapter 3 Using Cygwin Output version information and exit 3 6 3 How to start Cygserver Before you run Cygserver for the first time you should run the usr bin cygserver config script once It creates the default configuration file and upon request installs Cygserver as service when running under NT The script only performs a default install with no further options given to Cygserver when running as service Due to the wide configurability by changing the
47. bstantial POSIX http www pasc org POSIX Portable Operating System Interface system call functionality and a collection of tools which provide a Linux look and feel The Cygwin DLL works with all x86 versions of Windows since Windows 95 The API follows the Single Unix Specification http www opengroup org onlinepubs 009695399 nfindex html as much as possible and then Linux practice Two other major differences between Cygwin and Linux are the C library new1ib instead of glibc and default bin sh which is ash on Cygwin but bash on most Linux distributions With Cygwin installed users have access to many standard UNIX utilities They can be used from one of the provided shells such as bash or from the Windows Command Prompt Additionally programmers may write Win32 console or GUI applications that make use of the standard Microsoft Win32 API and or the Cygwin API As a result it is possible to easily port many significant UNIX programs without the need for extensive changes to the source code This includes configuring and building most of the available GNU software including the development tools included with the Cygwin distribution 1 2 Quick Start Guide for those more experienced with Windows If you are new to the world of UNIX you may find it difficult to understand at first This guide is not meant to be comprehensive so we recommend that you use the many available Internet resources to become acquainted with UNIX basics sea
48. changes were needed to match the expected UNIX semantics one of the most troublesome differences was that Winsock must be initialized before the first socket function is called As a result Cygwin has to perform this initialization when appropriate In order to support sockets across fork calls child processes initialize Winsock if any inherited file descriptor is a socket Unfortunately implicitly loading DLLs at process startup is usually a slow affair Because many processes do not use sockets Cygwin explicitly loads the Winsock DLL the first time it calls the Winsock initialization routine This single change sped up GNU configure times by thirty percent 1 6 10 Select The UNIX select function is another call that does not map cleanly on top of the Win32 API Much to our dismay we discovered that the Win32 select in Winsock only worked on socket handles Our implementation allows select to function normally when given different types of file descriptors sockets pipes handles and a custom dev windows Windows messages pseudo device Upon entry into the select function the first operation is to sort the file descriptors into the different types There are then two cases to consider The simple case is when at least one file descriptor is a type that is always known to be ready such as a disk file In that case select returns immediately as soon as it has polled each of the other types to see if they are ready The more complex case i
49. configuration file that s typically not necessary On Windows 9x Me just start Cygserver in any console window It s advisable to redirect stderr to a file of choice e g var log cygserver log and to use the e and Y options or the set the appropriate settings in the configuration file see below On Windows NT 2000 XP or 2003 you should always run Cygserver as a service under LocalSystem account This is the way it is installed for you by the usr bin cygserver config script 3 6 4 How to use the Cygserver services The Cygserver services are used by Cygwin applications only if you set the environment variable CYGWIN to contain the string server You must do this before starting the application Typically you don t need any other option so it s ok to set CYGWIN just to server It is not necessary to set the CYGWIN environment variable prior to starting the Cygserver process itself but it won t hurt to do so The easiest way is to set the environment variable CYGWIN to the values you want in the Windows system environment and to reboot the machine This is advisable since it allows you to set the variable once and then forget about it It also ensures that services as well as desktop applications have the same setting If you don t want that for whatever reason you can set the variable in the cygwin bat file which is used in the net distribution to start a Cygwin bash from the desktop In that file you can set the CYGWIN v
50. d packag find installed packages containing files not with cl dy list packag list the contents of installed packages not with cf h help give help about the info not with cfl V version output version information and exit The cygcheck program is a diagnostic utility for dealing with Cygwin programs If you are familiar with dpkg or rpm cygcheck is similar in many ways The major difference is that setup exe handles installing and uninstalling packages see Section 2 1 for more information The c option checks the version and status of installed Cygwin packages If you specify one or more package names cygcheck will limit its output to those packages or with no arguments it lists all packages A package will be marked Incomplete if files originally installed are no longer present The best thing to do in that situation is reinstall the package with setup exe To see which files are missing use the v option If you do not need to know the status of each package and want cygcheck to run faster add the 4d option and cygcheck will only output the name and version for each package If you list one or more programs on the command line cygcheck will diagnose the runtime environment of that program or programs providing the names of DLL files on which the program depends If you specify the s option cygcheck will give general system information If you list one or more programs on the command line and specify s cygcheck will r
51. different as you ll be using the GNU tools instead of the Microsoft tools For the most part your sources won t need to change at all However you should remove all __ export attributes from functions and replace them like this int foo int attribute dllexport int foo int i The Makefile is similar to any other UNIX like Makefile and like any other Cygwin makefile The only difference is that you use gcc mwindows to link your program into a GUI application instead of a command line application Here s an example myapp exe myapp o myapp res gcc mwindows myapp o myapp res o Q myapp res myapp rc resource h windres lt O coff o Q 71 Chapter 4 Programming with Cygwin Note the use of windres to compile the Windows resources into a COFF format res file That will include all the bitmaps icons and other resources you need into one handy object file Normally if you omitted the O coff it would create a Windows res format file but we can only link COFF objects So we tell windres to produce a COFF object but for compatibility with the many examples that assume your linker can handle Windows resource files directly we maintain the res naming convention For more information on windres consult the Binutils manual The following is a simple GUI mode Hello World program to help get you started hellogui c gui hello world x build gcc mwindows hellogui c o hellogui exe
52. dows NT W2K This is described in the ntsec section Under Windows 9x the situation is considerably different Since a security model is not provided Cygwin fakes file ownership by making all files look like they are owned by a default user and group id As under NT file permissions can still be determined by examining their read write execute status Rather than return an unimplemented error under Windows 9x the chown call succeeds immediately without actually performing any action whatsoever This is appropriate since essentially all users jointly own the files when no concept of file ownership exists It is important that we discuss the implications of our kernel using shared memory areas to store information about Cygwin processes Because these areas are not yet protected in any way in principle a malicious user could modify them to cause unexpected behavior in Cygwin processes While this is not a new problem under Windows 9x because of the lack of operating system security it does constitute a security hole under Windows NT This is because one user could affect the Cygwin programs run by another user by changing the shared memory information in ways that they could not in a more typical WinNT program For this reason it is not appropriate to use Cygwin in high security applications In practice this will not be a major problem for most uses of the library 1 6 4 File Access Cygwin supports both Win32 and POSIX style paths using
53. drawing characters The first setting called ansi is the default This character set contains various forms of latin characters used in European languages The name originates from the ANSI Latinl ISO 8859 1 standard used in Windows 1 0 though the character sets have since diverged from any standard The second setting selects an older DOS based character set containing various line drawing and special characters It is called oem since it was originally encoded in the firmware of IBM PCs by original equipment manufacturers OEMs If you find that some characters especially non US or graphical ones do not display correctly in Cygwin you can use this option to select an appropriate codepage 39 Chapter 3 Using Cygwin no envcache If set environment variable conversions between Win32 and POSIX are cached Note that this is may cause problems if the mount table changes as the cache is not invalidated and may contain values that depend on the previous mount table contents Defaults to set no export if set the final values of these settings are re exported to the environment as CYGWIN again Defaults to off error start Win32filepath if set runs Win32filepath when cygwin encounters a fatal error which is useful for debugging Win32filepath is usually set to the path to gdb or dumper for example C cygwin bin gdb exe There is no default set forkchunk 32768 causes fork to copy memory some number of bytes at a t
54. e During the download and installation setup exe show progress bars for the current task and total remaining disk space 2 1 8 Icons You may choose to install shortcuts on the Desktop and or Start Menu to start a bash shell If you prefer to use a different shell or the native Windows version of rxvt you can use these shortcuts as a guide to creating your own 2 1 9 Post Install Scripts Last of all setup exe will run any post install scripts to finish correctly setting up installed packages Since each script is run separately several windows may pop up If you are interested in what is being done see the Cygwin Package Contributor s Guide at http cygwin com setup html When the last post install script is completed setup exe will display a box announcing the completion A few packages such as the OpenSSH server require some manual site specific configuration Relevant documentation can be found in the usr doc Cygwin or usr share doc Cygwin directory 2 1 10 Troubleshooting Unfortunately the complex setup process means that odd problems can occur If you re having trouble downloading packages it may be network congestion so try a different mirror and or a different protocol i e HTTP instead of FTP If you notice something is not working after running setup you can check the setup exe log file at var 1og setup log full Make a backup of this file before running setup exe again and follow the steps for Reporting Problem
55. e ed re erret 12 2 1 7 Download and Installation Progress 12 2A BA ICONS sisi ecoute eee Oe See edet 13 21 9 Post Install Scripts srs i tret a e aee ite e ense tecti 13 2 1 10 Troubleshootimng entente torte dede Rete titine 13 2 2 Environment Variables eee egt E eet teneri etr a E TE 13 2 3 Changing Cygwin s Maximum Memory ss 14 2 4 NT security and usage Of nt sec sise 15 2 41 NT Secunty oen een en ner ee nt ni ann en tete teint iit 16 2 42 Process privileges RR ane OUR E UU RUOTE 18 2 4 3 File permissions out ene eee pim en tet et pires 18 244 NT SIDS an Cy SWIM seis iet Rd tide e eR e Eo Ete ee etel e etes 20 2 4 5 The mapping leak ss nid ertt Pei E Teei 22 24 6 The ACE ABL in b degit ne E 24 2 4 7 New setuid concept ie eto et gr RU MIRROR E HE tre ERR eI 24 2 4 8 Switching User Contexte nt nine oto eren RE re io E etae 27 2 4 9 Special values of user and group ids ss 27 2 5 Customizing bash oce ten EP Arena RI Ee ep Urt br ee IR pd 28 iii 3 BS TAR CILE 30 3 1 Mapping path names sister 30 33 1 Introduction te i et i e e ette cs 30 3 1 2 The Cygwin Mount Table ener enne nennen nene 30 3 1 3 Additional Path related Information ss 31 3 2 Text and Binary modes ses 32 3 22 T TheJssue o mins oe Duet o mede inm ot td tt beste E 32 3 2 2 The default Cygwin behavior sise 32 8 2 3 Example note OH UP P PO ORO E ERRORES 33
56. e stepping by default use OutputDebugString ssp off to disable stepping h help output usage information and exit Bb a Ld enable dll profiling A chart of relative DLL usage is produced after the run S sub threads trace sub threads too Dangerous if you have race conditions t trace eip trace every EIP value to a file TRACE SSP This gets big fast v verbose output verbose messages about debug events V version output version information and exit Example ssp 0x401000 0x403000 hello exe SSP The Single Step Profiler Original Author DJ Delorie 63 Chapter 3 Using Cygwin The SSP is a program that uses the Win32 debug API to run a program one ASM instruction at a time It records the location of each instruction used how many times that instruction is used and all function calls The results are saved in a format that is usable by the profiling program gprof although gprof will claim the values are seconds they really are instruction counts More on that later Because the SSP was originally designed to profile the cygwin DLL it does not automatically select a block of code to report statistics on You must specify the range of memory addresses to keep track of manually but it s not hard to figure out what to specify Use the objdump program to determine the bounds of the target s text section Let s say we re profiling cygwinl dll Make sure you ve built it with debug symbols else gprof won t r
57. e system from a UNIX machine or moving files back and forth to a UNIX machine you may want to access the files in binary mode The text files found there will normally be in UNIX NL format and you would want any files put there by Cygwin programs to be stored in a format understood by UNIX Be sure to remove CRs from all Makefiles and shell scripts and make sure that you only edit the files with DOS Windows editors that can cope with and preserve NL terminated lines Note that you can decide this on a disk by disk basis for example mounting local disks in text mode and network disks in binary mode You can also partition a disk for example by mounting c in text mode and c home in binary mode 3 2 5 Programming In the open function call binary mode can be specified with the flag 0 BINARY and text mode with O TEXT These symbols are defined in cnt1 h In the open function call binary mode can be specified by adding a b to the mode string Text mode is specified by adding a t to the mode string 34 Chapter 3 Using Cygwin The mode of a file can be changed by the call setmode d mode where d is a file descriptor an integer and mode is O BINARY or O TEXT The function returns O BINARY or O TEXT depending on the mode before the call and EOF on error 3 3 File permissions On Windows 9x systems files are always readable and Cygwin uses the native read only mode to determine if they are writable
58. ed ACL entries from the following list 61 Chapter 3 Using Cygwin u ser perm u ser uid perm g roup perm g roup gid perm m ask perm o ther perm Default entries are like the above with the additional default identifier For example d efault u ser uid perm perm is either a 3 char permissions string in the form rwx with the character for no permission or it is the octal representation of the permissions a value from 0 equivalent to to 7 rwx uid is a user name or a numerical uid gid is a group name or a numerical gid The following options are supported d Delete one or more specified entries from the file s ACL The owner group and others entries must not be deleted Acl entries to be deleted should be specified without permissions as in the following list u ser uid g roup gid d efault u ser uid d efault g roup gid d efault m ask d efault o ther f Take the Acl entries from ACL FILE one per line Whitespace characters are ignored and the character may be used to start a comment The special filename indicates reading from stdin Note that you can use this with getfacl and setfacl to copy ACLs from one file to another getfacl source file setfacl f target fil Required entries are one user entry for the owner of the file one group entry for the group of the file and one other entry If additional user and group entries are given a mask entry for the fi
59. eld to pw gecos which contains the NT user name including it s domain So you are able to login as each domain user The syntax is easy Just add an entry of the form U ntdomain ntusername to the pw gecos field Note that the SID must still remain the last field in pw gecos the king 1 1 Elvis Presley U STILLHERENelvis S 1 5 21 1234 5678 9012 1000 bin sh 21 Fora Chapter 2 Setting Up Cygwin local user just drop the domain the king 1 1 Elvis Presley U elvis S 1 5 21 1234 5678 9012 1000 bin sh In either case the password of the user is taken from the NT user database NOT from the passwd file Asin the previous chapter I give my personal etc passwd and etc group as examples Please note that I ve changed these files heavily There s no need to change them that way it s just for testing purposes and for fun Example 2 5 etc passwd root SYST 0 0 Administrators group S 1 5 32 544 EM 18 18 8 1 5 18 home system bin bash admin 500 513 S 1 5 21 1844237615 436374069 1060284298 500 home Administrator bin bash corinna 100 0 Corinna Vinschen S 1 5 21 1844237615 436374069 1060284298 1003 home corinn Gues t 501 546 S 1 5 21 1844237615 436374069 1060284298 501 home Guest bin bash Example 2 6 etc group root 1 5 32 544 0 local S 1 2 0 2 network S 1 5 2 3 interactive S 1 5 4 4 authenticatedusers 1 5 11 5 SYSTEM S 1 5 18 18 local svorso 1 5 T9719
60. embedded systems development The reuse of existing free implementations of such things as the glob regexp and getopt libraries saved us considerable effort In addition Cygwin uses Doug Lea s free malloc implementation that successfully balances speed and compactness The library accesses the malloc calls via an exported function pointer This makes it possible for a Cygwin process to provide its own malloc if it so desires 1 6 7 Process Creation The fork call in Cygwin is particularly interesting because it does not map well on top of the Win32 API This makes it very difficult to implement correctly Currently the Cygwin fork is a non copy on write implementation similar to what was present in early flavors of UNIX The first thing that happens when a parent process forks a child process is that the parent initializes a space in the Cygwin process table for the child It then creates a suspended child process using the Win32 CreateProcess call Next the parent process calls setjmp to save its own context and sets a pointer to this in a Cygwin shared memory area shared among all Cygwin tasks It then fills in the child s data and bss sections by copying from its own address space into the suspended child s address space After the child s address space is initialized the child is run while the parent waits on a mutex The child discovers it has been forked and longjumps using the saved jump buffer The child then sets the mutex the parent
61. eport on both The f option helps you to track down which package a file came from and 1 lists all files in a package For example to find out about usr bin less and its package Example 3 3 Example cygcheck usage cygcheck exe f usr bin less less 381 1 cygcheck exe 1 less usr bin less exe usr bin lessecho exe usr bin lesskey exe 46 Chapter 3 Using Cygwin usr man manl less 1 usr man manl lesskey 1 The h option prints additional helpful messages in the report at the beginning of each section It also adds table column headings While this is useful information it also adds some to the size of the report so if you want a compact report or if you know what everything is already just leave this out The v option causes the output to be more verbose What this means is that additional information will be reported which is usually not interesting such as the internal version numbers of DLLs additional information about recursive DLL usage and if a file in one directory in the PATH also occurs in other directories on the PATH The r option causes cygcheck to search your registry for information that is relevent to Cygwin programs These registry entries are the ones that have Cygwin in the name If you are paranoid about privacy you may remove information from this report but please keep in mind that doing so makes it harder to diagnose your problems The cygcheck program should be used to send informatio
62. er too that tell the debugger about line numbers variable names and other useful things These extra symbols and debugging information give your program enough information about the original sources so that the debugger can make debugging much easier for you In Windows versions of GNUPro GDB comes with a full featured graphical interface In Cygwin Net distributions GDB is only available as a command line tool To invoke GDB simply type gdb myapp exe at the command prompt It will display some text telling you about itself then gdb will appear to prompt you to enter commands Whenever you see this prompt it means that gdb is waiting for you to type in a command like run or help Oh type help to get help on the commands you can type in or read the GDB User s Manual for a complete description of GDB and how to use it If your program crashes and you re trying to figure out why it crashed the best thing to do is type run and let your program run After it crashes you can type where to find out where it crashed or info locals to see the values of all the local variables There s also a print that lets you look at individual variables or what pointers point to If your program is doing something unexpected you can use the break command to tell gdb to stop your program when it gets to a specific function or line number Example 4 3 break in gdb gdb break my function gdb break 47 Now when you type run your program will st
63. everything needed to understand the settings comment at the start of the file describes the syntax rules for the file The default options are shown in the file but are commented out It is generally a good idea to uncomment only options which you intend to change from the default values Since reading the options file on Cygserver startup doesn t take much time it s also considered good practice to keep all other comments in the file This keeps you from searching for clues in other sources 3 7 Cygwin Utilities Cygwin comes with a number of command line utilities that are used to manage the UNIX emulation portion of the Cygwin environment While many of these reflect their UNIX counterparts each was written specifically for Cygwin You may use the long or short option names interchangeably for 45 Chapter 3 Using Cygwin example help and h function identically All of the Cygwin command line utilities support the help and version options 3 7 1 cygcheck Usage cygcheck OPTIONS PROGRAM Check system information or PROGRAM library dependencies n check setup check packages installed via setup exe d dump only no integrity checking of package contents requires c S sysinfo system information not with k v verbose verbose output indented for cfls or programs r registry registry search requires s k keycheck perform a keyboard check session not with scfl f fin
64. f utilities such as ftp and telnet If you are having problems using one of these programs see if the alternate one works as expected There are a variety of other programs available for specific situations If your system does not have an always on network connection you may be interested in rasdial exe or alternatives for Windows 95 98 and ME for automating dialup connections Users who frequently change their network configuration can script these changes with netsh exe Windows 2000 and XP For proxy users the open source NTLM Authorization Proxy Server http apserver sourceforge net or the no charge Hummingbird SOCKS Proxy http www hummingbird com products nc socks index html may allow you to use Cygwin network programs in your environment 3 8 4 The cygutils package The optional cygutils package contains miscellaneous tools that are small enough to not require their own package It is not included in a default Cygwin install select it from the Utils category in setup exe Several of the cygutils tools are useful for interacting with Windows One of the hassles of Unix Windows interoperability is the different line endings on text files As mentioned in Section 3 2 Unix tools such as tr can convert between CRLF and LF endings but cygutils provides several dedicated programs conv d2u dos2unix u2d and unix2dos Use the ne1p switch for usage information 69 Chapter 3 Using Cygwin 3 8 5 Creating shortcuts with cyg
65. g it into cygwin s Just In Time debugging facility by adding error start x NVpathNtoNdumper exe to the CYGWIN environment variable Please note that x path to dumper exe is Windows style and not cygwin path If error_start is set this way then dumper will be started whenever some program encounters a fatal error dumper can be also be started from the command line to create a core dump of any running process Unfortunately because of a Windows API limitation when a core dump is created and dumper exits the target process is terminated too To save space in the core dump dumper doesn t write those portions of target process memory space that are loaded from executable and dll files and are unchangeable such as program code and debug info Instead dumper saves paths to files which contain that data When a core dump is loaded into gdb it uses these paths to load appropriate files That means that if you create a core dump on one machine and try to debug it on another you ll need to place identical copies of the executable and dlls in the same directories as on the machine where the core dump was created 3 7 4 getfacl Usage getfacl adn FILE FILE2 Display file and directory access control lists ACLs a all display the filename the owner the group and the ACL of the file O EE display the filename the owner the group and the default ACL of the directory if it exists h help output u
66. ggedOnUser to change user context of the current process or in CreateProcessAsUser to change user context of a spawned child process An important restriction is that the application using LogonUser must have special permissions Act as part of the operating system Replace process level token Increase quotas Note that administrators do not have all these user rights set by default Two new Cygwin calls are introduced to support porting setuid applications with a minimum of effort You only give Cygwin the right access token and then you can call seteuid or setuid as usual in POSIX applications The call to sexec is not needed anymore Porting a setuid application is illustrated by a short example First include all needed cygwin stuff ifdef _ CYGWIN include windows h include sys cygwin h Use the following define to determine the Windows version define is winnt GetVersion 0x80000000 endif struct passwd user pwd entry getpwnam username char cleartext password getpass Password ifdef CYGWIN Patch the typical password test if is winnt HANDLE token Try to get the access token from NT token cygwin logon user user pwd entry cleartext password if token INVALID HANDLE VALUE error exit Inform Cygwin about the new impersonation token Cygwin is able now to switch to that user context by setuid or seteuid calls Cygwi
67. h to the backend of the console device Another traditional Unix input output method ptys pseudo terminals are supported by Cygwin but not entirely by Windows The basic problem is that a Cygwin pty is a pipe and some Windows applications do not like having their input or output redirected to pipes To help deal with these issues Cygwin supports customizable levels of Windows verses Unix compatibility behavior To be most compatible with Windows programs use a DOS prompt running only the occasional Cygwin command or script Next would be to run bash with the default DOS box To make Cygwin more Unix compatible in this case set CYGWIN tty see Section 3 5 Alternatively the optional rxvt package provides a native Windows version of the popular X11 terminal emulator it is not necessary to set CYGWIN tty with rxvt Using rxvt exe provides the most Unix like environment but expect some compatibility problems with Windows programs 3 8 3 Cygwin and Windows Networking Many popular Cygwin packages such as ncftp lynx and wget require a network connection Since Cygwin relies on Windows for connectivity if one of these tools is not working as expected you may need to troubleshoot using Windows tools The first test is to see if you can reach the URL s host with ping exe one of the few utilities included with every Windows version since Windows 95 If you chose to install the inetutils package you may have both Windows and Cygwin versions o
68. hapter 3 Using Cygwin This chapter explains some key differences between the Cygwin environment and traditional UNIX systems It assumes a working knowledge of standard UNIX commands 3 1 Mapping path names 3 1 1 Introduction Cygwin supports both Win32 and POSIX style paths where directory delimiters may be either forward or back slashes UNC pathnames starting with two slashes and a network name are also supported POSIX operating systems such as Linux do not have the concept of drive letters Instead all absolute paths begin with a slash instead of a drive letter such as c and all file systems appear as subdirectories for example you might buy a new disk and make it be the disk2 directory Because many programs written to run on UNIX systems assume the existance of a single unified POSIX file system structure Cygwin maintains a special internal POSIX view of the Win32 file system that allows these programs to successfully run under Windows Cygwin uses this mapping to translate from POSIX to Win32 paths as necessary 3 1 2 The Cygwin Mount Table The mount utility program is used to to map Win32 drives and network shares into Cygwin s internal POSIX directory tree This is a similar concept to the typical UNIX mount program For those people coming from a Windows background the mount utility is very similar to the old DOS join in that it makes your drive letters appear as subdirectories somewhere else The mapping i
69. ime in the above example 32768 bytes 32Kb at a time The default is to copy as many bytes as possible which is preferable in most cases but may slow some older systems down no glob ignorecase if set command line arguments containing UNIX style file wildcard characters brackets question mark asterisk escaped with V are expanded into lists of files that match those wildcards This is applicable only to programs running from a DOS command line prompt Default is set This option also accepts an optional no ignorecase modifer If supplied wildcard matching is case insensitive The default is noignorecase no ntea if set use NT Extended Attributes to store UNIX like inode information This option only operates under Windows NT Defaults to not set Only FAT and NTFS support Extended Attributes not FAT32 so it s of no use there Furthermore on NTFS partitions ntsec which provides real permissions overrides ntea which only provides faked permissions So setting ntea only makes sense if you either have FAT partitions or if you switch off ntsec explicitely Warning This may create additional arge files on FAT partitions no ntsec if set use the NT security model to set UNIX like permissions on files and processes The file permissions can only be set on NTFS partitions FAT FAT32 don t support the NT file security Defaults to set For more information read the documentation in Section 2 4 no smbntsec if set
70. in bash guest 501 546 administrators 544 544 home root corinna 1000 547 Corinna Vinschen home corinna bin tcsh Example 2 2 etc group everyone 0 system 18 none 513 administrators 544 users 545 guests 546 powerusers 547 As you can see I changed my primary group membership from 513 None to 547 powerusers So all files I created inside of Cygwin were now owned by the powerusers group instead of None This is the way I liked it Groups may be mentioned in the passwd file too This has two advantages Because NT assigns them to files as owners a Is l is often more readable Moreover it s possible to assigned them to files as owners with Cygwin s chown The group system is the aforementioned synonym for the operating system itself and is normally the owner of processes that are started through service manager The same is true for files that are created by processes which are started through service manager 2 4 4 NT SIDs in Cygwin In Cygwin release 1 1 a new technique of using the etc passwd and etc group was introduced Both files may now contain SIDs of users and groups They are saved in the last field of pw gecos in etc passwd and in the gr passwd field in etc group This has the following advantages ntsec works better in domain environments 20 Chapter 2 Setting Up Cygwin Accounts users and groups may get another name in Cygwin than their NT account name The na
71. in bin directory comes first in your PATH 3 8 1 Pathnames Windows programs do not understand POSIX pathnames so any arguments that reference the filesystem must be in Windows or DOS format or translated Cygwin provides the cygpath utility for converting between Windows and POSIX paths A complete description of its options and examples of its usage are in Section 3 7 2 including a shell script for starting Windows Explorer in any directory The same format works for most Windows programs for example notepad exe cygpath aw Desktop Phone Numbers txt A few programs require a Windows style semicolon delimited path list which cygpath can translate from a POSIX path with the p option For example a Java compilation from bash might look like this javac cp cygpath pw SCLASSPATH hello java Since using quoting and subshells is somewhat awkward it is often preferable to use cygpath in shell scripts 3 8 2 Console Programs Another issue is receiving output from or giving input to the console based Windows programs Unfortunately interacting with Windows console applications is not a simple matter of using a translation utility Windows console applications and designed to run under command com or cmd exe and some do not deal gracefully with other situations Cygwin can receive console input only if it is also 68 Chapter 3 Using Cygwin running in a console DOS box since Windows does not provide any way to attac
72. indows program and so does not rely on the Cygwin DLL itself you can verify this with cygcheck As a result it does not understand POSIX pathnames or symlinks This program is mainly useful for debugging the Cygwin DLL itself 3 7 15 umount Usage umount exe OPTION lt posixpath gt Unmount filesystems A remove all mounts remove all mounts c remove cygdrive prefix remove cygdrive prefix h help output usage information and exit s system remove system mount default S remove system mounts remove all system mounts u user remove user mount U remove user mounts remove all user mounts v version output version information and exit The umount program removes mounts from the mount table If you specify a POSIX path that corresponds to a current mount point umount will remove it from the system registry area Administrator priviledges are required The u flag may be used to specify removing the mount from the user specific registry area instead The umount utility may also be used to remove all mounts of a particular type With the extended options it is possible to remove all mounts 2 all cygdrive automatically mounted mounts c all mounts in the current user s registry area U or all mounts in the system wide registry area S with Administrator privileges See Section 3 7 8 for more information on the mount table 67 Chapter 3 Using Cygwin 3 8 Using Cygwin effectively with Wind
73. information SIGHUP SIGINT SIGQUIT SIGILL SIGTRAP SIGABRT SIGE SIGFPE SIGKILL SIGBUS SIGSEGV SIGSYS SIGPIPE SIGALR SIGTER SIGURG SIGSTOP SIGTSTP SIGCONT SIGCHLD SIGTTIN SIGTTOU SIGPOLL SIGXCPU SIGXFSZ SIGVTALRM SIGPROF SIGWINCH I AO 01 amp C hr 000 120 C1 NN FP D NS ND NN NN N Nu FP WBN n Lo 21 28 hangup interrupt quit illegal instruction not reset when caught trace trap not reset when caught used by abort EMT instruction floating point exception kill cannot be caught or ignored bus error Segmentation violation bad argument to system call write on a pipe with no one to read it alarm clock software termination signal from kill urgent condition on IO channel sendable stop signal not from tty stop signal from tty continue a stopped process to parent on child stop or exit to readers pgrp upon background tty read like TTIN for output if tp t local amp LTOSTOP System V name for SIGIO exceeded CPU time limit xceeded file size limit virtual time alarm profiling time alarm window changed 51 Chapter 3 Using Cygwin SIGLOST 29 resource lost eg record lock lost SIGUSR1 30 user defined signal 1 SIGUSR2 31 user defined signal 2 3 7 6 mkgroup Usage mkgroup OPTION domain Prints etc group file to stdout Options 1 local print local group information c current print current group if a
74. lag and unlocked with the u flag Similarly c disables a user s ability to change passwords and c allows a user to change passwords For password expiry the e option disables expiration while the E option causes the password to expire according to the system s normal aging rules Use p to disable the password requirement for a user or P to require a password Administrators can also use passwd to change system wide password expiry and length requirements with the i n x and L options The i option is used to disable an account after the password has been expired for a number of days After a user account has had an expired password for NUM days the user may no longer sign on to the account The n option is used to set the minimum number of days before a password may be changed The user will not be permitted to change the password until MINDAYS days have elapsed The x option is used to set the maximum number of days a password remains valid After MAXDAYS days the password is required to be changed Allowed values for the above options are 0 to 999 The L option sets the minimum length of allowed passwords for users who don t belong to the administrators group to LEN characters Allowed values for the minimum password length are 0 to 14 In any of the above cases a value of 0 means no restrictions 58 Chapter 3 Using Cygwin Limitations Users may not be able to change their password on some systems 3 7 10 ps
75. ld show that it is a SID The next number is a version number which is always 1 The next number is the so called top level authority that identifies the source that issued the SID While each system in a NT network has it s own SID the situation is modified in NT domains The SID of the domain controller is the base SID for each domain user If an NT user has one account as domain user and another account on his local machine these accounts are under any circumstances DIFFERENT regardless of the usage of the same user name and password SID of a domain bar S 1 5 21 186985262 1144665072 740312968 SID of a user johndoe in the domain bar S 1 5 21 186985262 1144665072 740312968 1207 The last part of the SID the so called relative identifier RID is by default used as UID and or GID under Cygwin As the name and the above example implies this id is unique only relative to one system or domain 16 Chapter 2 Setting Up Cygwin Note that it s possible that a user has the same RID on two different systems The resulting SIDs are nevertheless different so the SIDs are representing different users in an NT network There is a big difference between UNIX IDs and NT SIDs the existence of the so called well known groups For example UNIX has no GID for the group of all users NT has an SID for them called Everyone in the English versions The SIDs of well known groups are not unique across a
76. le group class of the file and no duplicate user or group entries with the same uid gid If it is a directory one default user entry for the owner of the file one default group entry for the group of the file one default mask entry for the file group class and one default other entry 62 Chapter 3 Using Cygwin m Add or modify one or more specified ACL entries Acl entries is a comma separated list of entries from the same list as above r Causes the permissions specified in the mask entry to be ignored and replaced by the maximum permissions needed for the file group class s Like but substitute the file s ACL with Acl entries specified in a comma separated list on the command line While the d and m options may be used in the same command the f and s options may be used only exclusively Directories may contain default ACL entries Files created in a directory that contains default ACL entries will have permissions according to the combination of the current umask the explicit permissions requested and the default ACL entries Limitations Under Cygwin the default ACL entries are not taken into account currently 3 7 13 ssp Usage ssp options low pc high pc command Single step profile COMMAND e console trac trac very EIP value to the console Lots slower d disable disable single stepping by default use OutputDebugString ssp on to enable stepping e enable nable singl
77. me in etc passwd or etc group is transparently used by Cygwin applications e g chown chmod Is root 500 513 home root bin sh instead of adminstrator 500 513 home root bin sh Caution If you like to use the account as login account via telnet etc you have to remain the name unchanged or you have to use the special version of login which is part of the standard Cygwin distribution since 1 1 Cygwin UIDs and GIDs are now not necessarily the RID part of the NT SID root 0 513 8 1 5 21 54355234 56236534 345635656 500 home root bin sh instead of root 500 513 home root bin sh As in U X systems UIDs and GIDs numbering scheme now don t influence each other So it s possible to have same Id s for a user and a group Example 2 3 etc passwd root 0 0 1 5 21 54355234 56236534 345635656 500 home root bin sh Example 2 4 etc group root S 1 5 32 544 0 The tools mkpasswd and mkgroup create the needed entries by default If you don t want that you can use the options s or no sids I suggest not to do this since ntsec works better when having the SIDs available Please note that the pw gecos field in etc passwd is defined as a comma separated list The SID has to be the last field As aforementioned you are able to use Cygwin account names different from the NT account names If you want to login through telnet or something else you have to use the special login You may then add another fi
78. mple sets memory limit to 1024 MB regtool i set HKLM Software Cygnus Solutions Cygwin heap chunk in mb 1024 regtool v list HKLM Software Cygnus Solutions Cygwin Exit all running Cygwin processes and restart them Memory can be allocated up to the size of the system swap space minus any the size of any running processes The system swap should be at least as large as the physically installed RAM and can be modified under the System category of the Control Panel Here is a small program written by DJ Delorie that tests the memory allocation limit on your system 14 Chapter 2 Setting Up Cygwin main unsigned int bit 0x40000000 sum 0 char x while bit gt 4096 x malloc bit if x sum bit bit gt gt 1 printf 08x bytes 1fMb n sum sum 1024 0 1024 0 return 0 You can compile this program using gcc max memory c o max memory exe Run the program and it will output the maximum amount of allocatable memory 2 4 NT security and usage of ntsec The setting of UNIX like object permissions is controlled by the CYGWIN environment variable setting no ntsec which is set to nt sec by default The design goal of nt sec is to get a more UNIX like permission structure based upon the security features of Windows NT To describe the changes I will first give a short overview in Section 2 4 1 Process privileges discusses the changes in ntsec related to privileges on processes File permissions
79. n NT network but their meanings are unmistakable Examples of well known groups everyone S l 1 0 creator owner Sa1l 3 0 batch process via at SHl 5 3 authenticated users S l 5 T1 system 1 5 18 The last important group of SIDs are the predefined groups This groups are used mainly on systems outside of domains to simplify the administration of user permissions The corresponding SIDs are not unique across the network so they are interpreted only locally administrators 1 5 32 544 users 1 5 32 545 guests 1 5 32 546 Now how are permissions given to objects A process may assign an SD to the object The SD of an object consists of three parts the SID of the owner the SID of the group alist of SIDs with their permissions called access control list ACL UNIX is able to create three different permissions the permissions for the owner for the group and for the world In contrast the ACL has a potentially infinite number of members Every member is a so called access control element ACE An ACE contains three parts thetype of the ACE permissions described with a DWORD the SID for which the above mentioned permissions are set The two important types of ACEs are the access allowed ACE and the access denied ACE The ntsec functionality only used access allowed ACEs up to Cygwin version 1 1 0 Later versions also use access denied ACEs to reflect the UNIX permissions a
80. n about your system for troubleshooting when requested When asked to run this command save the output so that you can email it for example C cygwin gt cygcheck s v r h gt cygcheck output txt 3 7 2 cygpath Usage cygpath d m u w t TYPE f FILE OPTION NAME cygpath c HANDLE cygpath ADHPSW Convert Unix and Windows format paths or output system path information Ga Output type options d dos print DOS short form of NAMEs C PROGRA 1 m mixed like windows but with regular slashes C WINNT M mode report on mode of file currently binmode or textmode u unix default print Unix form of NAMEs cygdrive c winnt W windows print Windows form of NAMEs C WINNT t type TYPE print TYPE form dos mixed unix or windows Path conversion options a absolute output absolute path l1 long name print Windows long form of NAMEs with w m only p path NAME is a PATH list i e bin usr bin S short nam print DOS short form of NAMEs with w m only System information A allusers use All Users instead of current user for D P D desktop output Desktop directory and exit H homeroot output Profiles directory home root and exit 47 Chapter 3 Using Cygwin P smprograms output Start Menu Programs directory and exit S sysdir output system directory
81. n set impersonation token token 25 Chapter 2 Setting Up Cygwin else endif CYGWIN Use standard method for W9X as well hashed_password crypt cleartext_password salt if user pwd entry strcmp hashed password user pwd entry pw password error exit Everything else remains the same setegid user pwd entry pw gid seteuid user pwd entry pw uid execl bin sh The new Cygwin call to retrieve an access token is defined as follows finclude lt windows h gt finclude sys cygwin h HANDLE cygwin logon user struct passwd pw const char cleartext password You can call that function as often as you want for different user logons and remember the access tokens for further calls to the second function finclude lt windows h gt include lt sys cygwin h gt void T cygwin_set_impersonation_token HANDLE hToken is the call to inform Cygwin about the user context to which further calls to setuid seteuid should switch to While you always need the correct access token to do a setuid seteuid to another user s context you are always able to use setuid seteuid to return to your own user context by giving your own uid as parameter If you have remembered several access tokens from calls to cygwin logon user you can switch to different user contexts by observing the following order Ccygwin set impersonation token userl token seteuid userl uid 26
82. n sys ac1 h as typedef struct acl int a type entry type uid t a id UID GID mode t a perm permissions aclent t The a perm member of the aclent t type contains only the bits for read write and execute as in the file mode If e g read permission is granted all read bits S IRUSR S IRGRP S IROTH are set CLASS OBJ or MASK ACL entries are not fully implemented yet The new API calls are acl 2 facl 2 aclcheck 3 aclsort 3 acltomode 3 aclfrommode 3 acltopbits 3 aclfrompbits 3 acltotext 3 aclfromtext 3 Like in Solaris Cygwin has two new commands for working with ACLs on the command line getfacl and setfacl Online man pages for the aforementioned commands and API calls can be found on http docs sun com 2 4 7 New setuid concept UNIX applications which have to switch the user context are using the setuid and seteuid calls which are not part of the Windows API Nevertheless these calls are supported under Windows NT W2K since 24 Chapter 2 Setting Up Cygwin Cygwin release 1 1 3 Because of the nature of NT security an application which needs the ability has to be patched though NT uses so called access tokens to identify a user and it s permissions To switch the user context the application has to request such an access token This is typically done by calling the NT API function LogonUser The access token is returned and either used in ImpersonateLo
83. named mkgroup will be shown as 27722772 Note that since the special user and group names are just indicators nothing prevents you from actually having a user named mkpasswd in etc passwd or a group named mkgroup in etc group If you do that however be aware of the possible confusion 2 5 Customizing bash To set bash up so that cut and paste work properly click on the Properties button of the window then on the Misc tab Make sure that Quick Edit is checked and Fast Pasting isn t These settings will be remembered next time you run bash from that shortcut Similarly you can set the working directory inside the Program tab The entry HOME is valid Your home directory should contain three initialization files that control the behavior of bash They are profile bashrc and inputrc These initialization files will only be read if HOME is defined before starting bash profile other names are also valid see the bash man page contains bash commands It is executed when bash is started as login shell e g from the command bash login This is a useful place to define and export environment variables and bash functions that will be used by bash and the programs invoked by bash It is a good place to redefine PATH if needed We recommend adding a to the end of PATH to also search the current working directory contrary to DOS the local directory is not searched by default Also to avoid delay
84. nges may result in an unstable or broken system The Cygwin proc is not as complete as the one in Linux but it provides significant capabilities The procps package contains several utilities that use it 3 4 5 The pathnames To circumvent the limitations on shell line length in the native Windows command shells Cygwin programs expand their arguments starting with in a special way If a file pathname exists the argument pathname expands recursively to the content of pathname Double quotes can be used inside the file to delimit strings containing blank space Embedded double quotes must be repeated In the following example compare the behaviors of the bash built in echo and of the program bin echo 38 Chapter 3 Using Cygwin Example 3 2 Using pathname bash echo This is a long line gt mylist bash echo mylist mylist c gt c cygwin bin echo mylist This is a long line 3 5 The CYGWIN environment variable The CYGWIN environment variable is used to configure many global settings for the Cygwin runtime system It contains the options listed below separated by blank characters Many options can be turned off by prefixing with no no binmode if set non disk e g pipe and COM ports file opens default to binary mode no CRLF translation instead of text mode Defaults to set binary mode By default devices are opened in binary mode so this option has little effect on normal cygwin operatio
85. nloads a small text file called setup bz2 that contains a list of packages available from that site along with some basic information about each package which setup exe parses and uses to create the chooser window For details about the format of this file see the setup exe homepage http sources redhat com cygwin apps setup html The chooser is the most complex part of setup exe Packages are grouped into categories and one package may belong to multiple categories assigned by the volunteer package maintainer Each package can be found under any of those categories in the heirarchial chooser view By default setup exe will install only the packages in the Base category and their dependencies resulting in a minimal Cygwin installation However this will not include many commonly used tools such as gee which you will find in the Devel category Since setup exe automatically selects dependencies be careful not to unselect any required packages In particular everything in the Base category is required You can change setup exe s view style which is helpful if you know the name of a package you want to install but not which category it is in Click on the view button and it will rotate between Category the default Full all packages and Partial only packages to be upgraded If you are familiar with Unix you will probably want to at least glance through the Fu11 listing for your favorite tools Once you have an existing Cygwin installati
86. ns It does affect two things however For non NTFS filesystems this option will control the line endings for standard output input error for redirection from the Windows command shell It will also affect the default translation mode of a pipe although most shells set the pipe to binary by default check case level THIS OPTION IS DEPRECATED Don t use it unless you know what you re doing and don t see any way around it And even then this option is error prone slows down Cygwin and not well maintained This option controls the behavior of Cygwin when a user tries to open or create a file using a case different from the case of the path as saved on the disk 1eve1 is one of relaxed adjust and strict relaxed which is the default behaviour simply ignores case That s the default for native Windows applications as well adjust behaves mostly invisible The POSIX input path is internally adjusted in case so that the resulting DOS path uses the correct case throughout You can see the result when changing the directory using a wrong case and calling bin pwd afterwards e Strict results in a error message if the case isn t correct Trying to open a file Foo while a file 00 exists results in a no such file or directory error Trying to create a file BAR while a file Bar exists results in a Filename exists with different case error codepage ansiloem Windows console applications can use different character sets codepages for
87. ns B E DISCARDABLI EG items E helpid data string number etc data 78 Chapter 4 Programming with Cygwin items string id flags EPARATOR P string flags BEG menuitems END o d ZEHTAAMNNH v SS K d MENUEX suboptions BEG items END F string string xd T string id type state POPUP string BEG items END POPUP string id BEG items END POPUP string id type BEG items END POPUP string id type state helpid BEG items END Z oZ Z eoe z t UHHH NN id MESSAGETABLE memflags filename memflags defaults to MOVEABLE id RCDATA suboptions BEG string number string number etc END STRINGTABLE suboptions BEG strings END strings id string id string User data id id suboptions BEG string number string number etc END id VERSIONINFO stuffs BEG verblocks END stuffs FILEVERSION num num num num PRODUCTVERSION num num num num FILEFLAGSMASK num FILEOS num FILETYPE num FILESUBTYPE num verblocks BLOCK StringFileInfo BEG BLOCK BEG vervals END END BLOCK VarFileInfo BEG BLOCK BEG vertrans END END vervals VALUE foo bar vertrans VALUE num num
88. nt is a system wide mount point that is visible to all users running Cygwin programs whereas the d mount is only visible to the current user The mount utility is also the mechanism for adding new mounts to the mount table The following example demonstrates how to mount the directory pollux home joe data to data Example 3 10 Adding mount points c cygwin gt ls data ls data No such file or directory c cygwin gt mount pollux home joe data data mount warning data does not exist c cygwin gt mount pollux home joe data on data type sytem binmode c cygwin bin on usr bin type system binmode c cygwin lib on usr lib type system binmode c cygwin on type system binmode c on c type user binmode noumount d on d type user binmode noumount Note that mount was invoked from the Windows command shell in the previous example In many Unix shells including bash it is legal and convenient to use the forward in Win32 pathnames since the is the shell s escape character The s flag to mount is used to add a mount in the system wide mount table used by all Cygwin users on the system instead of the user specific one System wide mounts are displayed by mount as being of the system type as is the case for the partition in the last example Under Windows NT only those users with Administrator priviledges are permitted to modify the system wide mount table Note that a given POSIX path may only
89. nvolves waiting for socket or pipe file descriptors to be ready This is accomplished by the main thread suspending itself Chapter 1 Cygwin Overview after starting one thread for each type of file descriptor present Each thread polls the file descriptors of its respective type with the appropriate Win32 API call As soon as a thread identifies a ready descriptor that thread signals the main thread to wake up This case is now the same as the first one since we know at least one descriptor is ready So select returns after polling all of the file descriptors one last time Chapter 2 Setting Up Cygwin 2 1 Internet Setup To install the Cygwin net release go to http cygwin com and click on Install Cygwin Now http cygwin com setup exe This will download a GUI installer called setup exe which can be run to download a complete cygwin installation via the internet Follow the instructions on each screen to install Cygwin The setup exe installer is designed to be easy for new users to understand while remaining flexible for the experienced The volunteer development team is constantly working on setup exe before requesting a new feature check the wishlist in the CVS README http sources redhat com cgi bin cvsweb cgi setup README cvsroot cygwin apps amp rev 2 It may already be present in the CVS version Since the default value for each option is the logical choice for most installations you can get a working minim
90. ols were previously only built natively so we had to modify their configure scripts to be compatible with cross compilation Other than the configuration changes very few source level changes had to be made Running bash with the development tools and user tools in place Windows 9x and NT look like a flavor of UNIX from the perspective of the GNU configure mechanism Self hosting was achieved as of the beta 17 1 release in October 1996 The entire Cygwin toolset was available as a monolithic install In April 2000 the project announced a New Cygwin Net Release http www cygwin com ml cygwin 2000 04 msg00269 html which provided the native Win32 program setup exe to install and upgrade each package separately Since then the Cygwin DLL and setup exe have seen continuous development 1 6 Highlights of Cygwin Functionality 1 6 1 Introduction When a binary linked against the library is executed the Cygwin DLL is loaded into the application s text segment Because we are trying to emulate a UNIX kernel which needs access to all processes Chapter 1 Cygwin Overview running under it the first Cygwin DLL to run creates shared memory areas that other processes using separate instances of the DLL can access This is used to keep track of open file descriptors and assist fork and exec among other purposes In addition to the shared memory regions every process also has a per process structure that contains information such as process id user id
91. omplete historical look Cygwin is Geoffrey J Noer s 1998 paper Cygwin32 A Free Win32 Porting Layer for UNIX Applications which can be found at the 2nd USENIX Windows NT Symposium Online Proceedings http www usenix org publications library proceedings usenix nt98 technical html Cygwin began development in 1995 at Cygnus Solutions now part of Red Hat Software The first thing done was to enhance the development tools gcc gdb gas etc so that they could generate and interpret Win32 native object files The next task was to port the tools to Win NT 9x We could have done this by rewriting large portions of the source to work within the context of the Win32 API But this would have meant spending a huge amount of time on each and every tool Instead we took a substantially different approach by writing a shared library the Cygwin DLL that adds the necessary UNIX like functionality missing from the Win32 API ork spawn signals select sockets etc We call this new interface the Cygwin API Once written it was possible to build working Win32 tools using UNIX hosted cross compilers linking against this library From this point we pursued the goal of producing native tools capable of rebuilding themselves under Windows 9x and NT this is often called self hosting Since neither OS ships with standard UNIX user tools fileutils textutils bash etc we had to get the GNU equivalents working with the Cygwin API Most of these to
92. on the setup exe chooser is also used to manage your Cygwin installation Information on installed packages is kept in the et c setup directory of your Cygwin installation if setup exe cannot find this directory it will act just like you had no Cygwin installation If setup exe finds a newer version of an installed package available it will automatically mark it to be upgraded To Uninstall Reinstall or get the Source for an existing package click on Keep to toggle it Also to avoid the need to reboot after upgrading make sure to close all Cygwin windows and stop all Cygwin processes before setup exe begins to install the upgraded package The final feature of the setup exe chooser is for Previous and Experimental packages By default the chooser shows only the current version of each package though mirrors have at least one previous version and occasionally there is a testing or beta version of a package available To see these package click on the Prev or Exp radio button Be warned however that the next time you run setup exe it will try to replace old or experimental versions with the current stable version 2 1 7 Download and Installation Progress First setup exe will download all selected packages to the local directory chosen earlier Before installing setup exe performs a checksum on each package If the local directory is a slow medium such 12 Chapter 2 Setting Up Cygwin as a network drive this can take a long tim
93. on0O whole disk dev sdal device harddisk0O partitionl first partition dev sdal5 device harddisk0 partition15 fifteenth partition dev sdb NdeviceMharddisklNpartitionO dev sdb1 device harddiskl partitionl up to dev sdl device harddisk11 partition0 dev sdll device harddisk11 partitionl dev sd115 device harddiskl1 partition15 if you don t like these device names feel free to create symbolic links as they are created on Linux systems for convenience In s dev scd0 dev cdrom in s dev nst0 dev tape Warning Note that you can t use the mount table to map from fixed device name to your own device name or to map from internal NT device name to your own device name Also using symbolic links to map from the internal NT device name to your own device name will not do what you want The following three examples will not work as expected mount f b dev nst0 dev tape DOES NOT WORK mount f b device tape0 dev tape DOES NOT WORK ln s device tape0 dev tape 4 DOES NOT WORK 3 4 3 The exe extension Executable program filenames end with exe but the exe need not be included in the command so that traditional UNIX names can be used However for programs that end in bat and com you cannot omit the extension As a side effect the Is filename gives information about filename exe if filename exe exists and filename does not In the same situation the function call stat ilename gives inf
94. only return information for the specified user h help displays this message v version version information and exit One of 1 d or g must be given on NT W2K The mkpasswd program can be used to help configure your Windows system to be more UNIX like by creating an initial etc passwd from your system information Its use is essential on the NT series Windows NT 2000 and XP to include Windows security information but the actual passwords are determined by Windows not by the content of etc passwd On the Win9x series Windows 95 98 and Me the password field must be replaced by the output of crypt your password if remote access is desired To initially set up your machine if you are a local user you d do something like this Example 3 7 Setting up the passwd file for local accounts mkdir etc mkpasswd 1 etc passwd Note that this information is static If you change the user information in your system you ll need to regenerate the passwd file for it to have the new information The a and 1 options allow you to specify where the information comes from the local machine or the domain default or given or both With the a option the program contacts the Domain Controller which my be unreachable or have restricted access An entry for the current domain user can then be created by using the option c together with 1 but c has no effect when used with a The o option 53 Chapter 3 Using Cygwin allow
95. op at that breakpoint and you can use the other gdb commands to look at the state of your program at that point modify variables and step through your program s statements one at a time Note that you may specify additional arguments to the run command to provide command line arguments to your program These two cases are the same as far as your program is concerned Example 4 4 Debugging with command line arguments myprog t foo queue 47 gdb myprog gdb run t foo queue 47 74 Chapter 4 Programming with Cygwin 4 3 Building and Using DLLs DLLs are Dynamic Link Libraries which means that they re linked into your program at run time instead of build time There are three parts to a DLL the exports the code and data the import library The code and data are the parts you write functions variables etc All these are merged together like if you were building one big object files and put into the dll They are not put into your exe at all The exports contains a list of functions and variables that the dll makes available to other programs Think of this as the list of global symbols the rest being hidden Normally you d create this list by hand with a text editor but it s possible to do it automatically from the list of functions in your code The dlltool program creates the exports section of the dll from your text file of exported symbols The import library is a regular UNIX like a library bu
96. or the current domain user can then be created by using the option c together with 1 but c has no effect when used with a The o option allows for special cases such as multiple domains where the GIDs might match otherwise The s option omits the NT Security Identifier SID For more information on SIDs see Section 2 4 in the Cygwin User s Guide The u option causes mkgroup to enumerate the users for each group placing the 22 Chapter 3 Using Cygwin group members in the gr mem last field Note that this can greatly increase the time for mkgroup to run in a large domain Having gr mem fields is helpful when a domain user logs in remotely while the local machine is disconnected from the Domain Controller The g option only prints the information for one group 3 7 7 mkpasswd Usage mkpasswd OPTION domain Prints etc passwd file to stdout Options 1 1ocal print local user accounts c current print current account if a domain account d domain print domain accounts from current domain if no domains specified Oo id offset offset change the default offset 10000 added to uids in domain accounts g local groups print local group information too if no domains specified m no mount don t use mount points for home dir s no sids don t print SIDs in GCOS field this affects ntsec p path to home path use specified path and not user account home dir or home u username usernam
97. ormation 37 Chapter 3 Using Cygwin about filename exe The two files can be distinguished by examining their inodes as demonstrated below C gt ls a a exe b exe C gt ls i a a exe 445885548 a 435996602 a exe C gt ls i b b exe 432961010 b 432961010 b exe If a shell script myprog and a program myprog exe coexist in a directory the program has precedence and is selected for execution of myprog The gcc compiler produces an executable named ilename exe when asked to produce ilename This allows many makefiles written for UNIX systems to work well under Cygwin Unfortunately the install and strip commands do distinguish between ilename and filename exe They fail when working on a non existing filename even if filename exe exists thus breaking some makefiles This problem can be solved by writing install and strip shell scripts to provide the extension exe when needed 3 4 4 The proc filesystem Cygwin like Linux and other similar operating systems supports the proc virtual filesystem The files in this directory are representations of various aspects of your system for example the command cat proc cpuinfo displays information such as what model and speed processor you have One unique aspect of the Cygwin proc filesystem is proc registry which displays the Windows registry with each KEY as a directory and each VALUE as a file As anytime you deal with the Windows registry use caution since cha
98. oup and Everyone 18 Chapter 2 Setting Up Cygwin The complete settings of UNIX like permissions can be found in the file security cc The two functions get nt attribute and set nt attribute are the main code The reading and writing of the SDs is done by the functions tread sd and write sd write sd uses the function BackupRead instead of the simpler function SetFileSecurity because the latter is unable to set owners different from the caller If you are creating a file foo outside of Cygwin you will see something like the following on Is In If your login is member of the administrators group rwxrwxrwx 1 544 513 foo if not rwxrwxrwx 1 1000 513 foo Note the user and group IDs 544 is the UID of the administrators group This is a feature P of WinNT If you are a member of the administrators group every file that you create is owned by the administrators group instead of by you The second example shows the UID of the first user that has been created with NT s the user administration tool The users and groups are sequentially numbered starting with 1000 Users and groups are using the same numbering scheme so a user and a group don t share the same ID In both examples the GID 513 is of special interest This GID is a well known group with different naming in local systems and domains Outside of domains the group is named None Kein in German
99. output a series of commands that could recreate both user and system mount points You can save this output as a backup when experimenting with the mount table It also makes moving your settings to a different machine much easier The o option is the method via which various options about the mount point may be recorded The following options are available note that most of the options are duplicates of other mount flags user mount lives user specific mount system mount lives in system table default binary files default to binary mode default text files default to CRLF text mode lin ndings exec files below mount point are all executabl notexec files below mount point are not executabl cygexec files below mount point are all cygwin executables nosuid no suid files are allowed currently unimplemented managed directory is managed by cygwin Mixed case and special characters in filenames are allowed 3 7 8 2 Cygdrive mount points Whenever Cygwin cannot use any of the existing mounts to convert from a particular Win32 path to a POSIX one Cygwin will instead convert to a POSIX path using a default mount point cygdrive For example if Cygwin accesses z foo and the z drive is not currently in the mount table then z V will be accessible as cygdrive z The mount utility can be used to change this default automount prefix through the use of the change cygdrive prefix option In the foll
100. owing example we will set the automount prefix to Example 3 11 Changing the default prefix c cygwin gt mount change cygdrive prefix 56 Chapter 3 Using Cygwin Note that the cygdrive prefix can be set both per user and system wide and that as with all mounts a user specific mount takes precedence over the system wide setting The mount utility creates system wide mounts by default if you do not specify a type Use the s or u flag to indicate a system or user mount respectively You can always see the user and system cygdrive prefixes with the p option Using the b flag with change cygdrive prefix makes all new automounted filesystems default to binary mode file accesses 3 7 8 3 Limitations Limitations there is a hard coded limit of 30 mount points Also although you can mount to pathnames that do not start with there is no way to make use of such mount points Normally the POSIX mount point in Cygwin is an existing empty directory as in standard UNIX If this is the case or if there is a place holder for the mount point such as a file a symbolic link pointing anywhere or a non empty directory you will get the expected behavior Files present in a mount point directory before the mount become invisible to Cygwin programs It is sometimes desirable to mount to a non existent directory for example to avoid cluttering the root directory with names such as a b c pointing to disks Although mount will give
101. ows Cygwin is not a full operating system and so must rely on Windows for accomplishing some tasks For example Cygwin provides a POSIX view of the Windows filesystem but does not provide filesystem drivers of its own Therefore part of using Cygwin effectively is learning to use Windows effectively Many Windows utilities provide a good way to interact with Cygwin s predominately command line environment For example ipconfig exe provides information about network configuration and net exe views and configures network file and printer resources Most of these tools support the switch to display usage information Unfortunately no standard set of tools included with all versions of Windows exists If you are unfamiliar with the tools available on your system here is a general guide Windows 95 98 and ME have very limited command line configuration tools Windows NT 4 0 has much better coverage which Windows 2000 and XP expanded Microsoft also provides free downloads for Windows NT 4 0 the Resource Kit Support Tools Windows 2000 the Resource Kit Tools and XP the Windows Support Tools Additionally many independent sites such as download com http download com com simtel net http simtel net and sysinternals com http sysinternals com provide command line utilities A few Windows tools such as find exe and sort exe may conflict with the Cygwin versions make sure that you use the full path usr bin find or that your Cygw
102. provided All tools may be used from the Microsoft command prompt with full support for normal Windows pathnames 1 3 Quick Start Guide for those more experienced with UNIX If you are an experienced UNIX user who misses a powerful command line environment you will enjoy Cygwin Note that there are some workarounds that cause Cygwin to behave differently than most UNIX like operating systems these are described in more detail in Section 3 8 Any time you want to update or install a Cygwin package use the graphical setup exe program By default setup exe only installs a minimal set of packages so look around and choose your favorite utilities on the package selection screen You may also search for specfic tools on the Cygwin website s Setup Package Search http cygwin com packages For more information about what each option in setup exe means see Section 2 1 Another option is to install everything by clicking on the Default field next to the A11 category However be advised that this will download and install several hundreds of megabytes of software to your computer The best plan is probably to click on individual categories and install either entire categories or packages from the categories themselves After installation you can find Cygwin specific documentation in the usr share doc Cygwin directory Developers coming from a UNIX background will find a set of utilities they are already comfortable using including a working UNI
103. rch for UNIX basics or UNIX tutorial To install a basic Cygwin environment run the setup exe program and click Next at each page The default settings are correct for most users If you want to know more about what each option means see Section 2 1 Use setup exe any time you want to update or install a Cygwin package If you are installing Cygwin for a specific purpose use it to install the tools that you need For example if you want to compile C programs you need the gcc g package and probably a text editor like nano When running setup exe clicking on categories and packages in the package installation screen will provide you with the ability to control what is installed or updated Another option is to install everything by clicking on the Default field next to the A11 category However be advised that this will download and install several hundreds of megabytes of software to your computer The best plan is probably to click on individual categories and install either entire categories or packages from the categories themselves After installation you can find Cygwin specific documentation in the usr share doc Cygwin directory Chapter 1 Cygwin Overview Developers coming from a Windows background will find a set of tools capable of writing console or GUI executables that rely on the Microsoft Win32 API The dlltool utility may be used to write Windows Dynamically Linked Libraries DLLs The resource compiler windres is also
104. ror messages so you can use the exit status of the program to detect if a key exists or not for example You must provide regtool with an action following options if any Currently the action must be add set check get list remove set Or unset 60 Chapter 3 Using Cygwin The add action adds a new key The check action checks to see if a key exists the exit code of the program is zero if it does nonzero if it does not The get action gets the value of a value of a key and prints it and nothing else to stdout Note if the value doesn t exist an error message is printed and the program returns a non zero exit code If you give q it doesn t print the message but does return the non zero exit code The list action lists the subkeys and values belonging to the given key With list the k option instructs regtool to print only KEYs and the 1 option to print only VALUEs The p option postfixes a to each KEY but leave VALUEs with no postfix The remove action removes a key Note that you may need to remove everything in the key before you may remove it but don t rely on this stopping you from accidentally removing too much The set action sets a value within a key e means it s an expanding string REG EXPAND SZ that contains embedded environment variables i means the value is an integer REG DWORD m means it s a multi string REG MULTI SZ s means the value is a string REG SZ If you don t specify one
105. rst parameter to the function call CreateSemaphore is an SA Without ntsec this SA assigns default security to the semaphore There is a simple disadvantage Only the owner of the process may send signals to it Or in other words if the owner of the process is not a member of the administrators group no administrator may kill the process This is especially annoying if processes are started via service manager Ntsec now assigns an SA to the process control semaphore that has each permission set for the user of the process for the administrators group and for system which is a synonym for the operating system itself The creation of this SA is done by the function sec_user that can be found in shared cc Each member of the administrators group is now allowed to send signals to any process created in Cygwin regardless of the process owner Moreover each process now has the appropriate security settings when it is started via CreateProcess You will find this in function spawn_guts in module spawn cc The security settings for starting a process in another user context have to add the SID of the new user too In the case of the CreateProcess AsUser call sec user creates an SA with an additional entry for the sid of the new user 2 4 3 File permissions If ntsec is turned on file permissions are set as in UNIX An SD is assigned to the file containing the owner and group and ACEs for the owner the gr
106. s Wl enable auto import Wl whole archive old_libs Wl no whole archive S dependency_libs The name of your library is module prefixed with cyg for the DLL and 1i for the import library Cygwin DLLs use the cyg prefix to differentiate them from native Windows MinGW DLLs see the MinGW website http mingw org for more details 01d libs are all your object files bundled together in static libs or single object files and the dependency libs are import libs you need to link against e g 1png lz L usr local special lmyspeciallib 4 3 2 Linking Against DLLs If you have an existing DLL already you need to build a Cygwin compatible import library If you have the source to compile the DLL see Section 4 3 1 for details on having gcc build one for you If you do not have the source or a supplied working import library you can get most of the way by creating a def file with these commands you might need to do this in bash for the quoting to work correctly echo EXPORTS gt foo def nm foo dll grep T sed s T gt gt foo def Note that this will only work if the DLL is not stripped Otherwise you will get an error message No symbols in foo dll Once you have the def file you can create an import library from it like this 76 Chapter 4 Programming with Cygwin dlltool def foo def dllname foo dll output lib foo a 4 4 Defining Windows Resources windres re
107. s for special cases such as multiple domains where the UIDs might match otherwise The g option creates a local user that corresponds to each local group This is because NT assigns groups file ownership The m option bypasses the current mount table so that for example two users who have a Windows home directory of H could mount them differently The s option omits the NT Security Identifier SID For more information on SIDs see Section 2 4 in the Cygwin User s Guide The p option causes mkpasswd to use the specified prefix instead of the account home dir or home For example this command Example 3 8 Using an alternate home root mkpasswd 1 p cygpath H etc passwd would put local users home directories in the Windows Profiles directory On Win9x machines the u option creates an entry for the specified user On the NT series it restricts the output to that user greatly reducing the amount of time it takes in a large domain 3 7 8 mount Usage mount OPTION lt win32path gt lt posixpath gt Display information about mounted filesystems or mount a filesystem b binary default text files ar quivalent to binary files newline Mn c change cygdrive prefix change the cygdrive path prefix to lt posixpath gt f force force mount don t warn about missing mount point directories h help output usage information and exit m mount commands write mount commands to replicate u
108. s slower than normal it s best to understand all the options so that you can narrow down the parts of your program you need to single step v verbose This prints messages about threads starting and stopping OutputDebugsString calls DLLs loading etc t and c tracing With t every step s address is written to the file trace ssp This can be used to help debug functions since it can trace multiple threads Clever use of scripts can match addresses with disassembled opcodes if needed Warning creates huge files very quickly c prints each address to the console useful for debugging key chunks of assembler Use addr21ine C f s foo ex lt trace ssp gt lines ssp and then perl cvttrace to convert to symbolic traces s subthreads Usually you only need to trace the main thread but sometimes you need to trace all threads so this enables that It s also needed when you want to profile a function that only a subthread 65 Chapter 3 Using Cygwin calls However using OutputDebugString automatically enables profiling on the thread that called it not the main thread 1 dll profiling Generates a pretty table of how much time was spent in each dll the program used No sense optimizing a function in your program if most of the time is spent in the DLL I usually use the v s and 1 options ssp v s 1 d 0x61001000 0x61080000 hello exe 3 7 14 strace Usage strace exe OPTIONS lt command line gt
109. s stored in the current user s Cygwin mount table in the Windows registry so that the information will be retrieved next time the user logs in Because it is sometimes desirable to have system wide as well as user specific mounts there is also a system wide mount table that all Cygwin users inherit The system wide table may only be modified by a user with the appropriate privileges Administrator privileges in Windows NT The current user s table is located under HKEY CURRENT USER Software Cygnus Solutions Cygwin mounts v lt version gt where version is the latest registry version associated with the Cygwin library this version is not the same as the release number The system wide table is located under the same subkeys under HRKEY LOCAL SYSTEM The user mount table takes precedence over the system wide table if a path is mounted in both This includes the setting of the cygdrive prefix 30 Chapter 3 Using Cygwin The mount command can set the POSIX root to any directory in the Windows file system In absence of such a mount Cygwin maps to the root of the current Windows working directory for example H or computer share Normally Cygwin s setup exe creates the initial mount point for the POSIX root Whenever Cygwin generates a Win32 path from a POSIX one it uses the longest matching prefix in the mount table Thus if C is mounted as c and also as then Cygwin would translate C oo bar to c oo bar This tran
110. s well as possible The possible permissions on objects are more detailed than in UNIX For example the permission to delete an object is different from the write permission With the aforementioned method NT is able to grant or revoke permissions to objects in a far more specific way But what about cygwin In a POSIX environment it would be fine to have the security 17 Chapter 2 Setting Up Cygwin behavior of a POSIX system The NT security model is MOSTLY able to reproduce the POSIX model The ntsec method tries to do this in cygwin You ask Mostly Why mostly Because there s a leak in the NT model I will describe that in detail in chapter 5 Creating explicit object security is not that easy so you will often see only two simple variations in use default permissions computed by the operating system each permission to everyone For parameters to functions that create or open securable objects another data structure is used the security attributes SA This structure contains an SD and a flag that specifies whether the returned handle to the object is inherited to child processes or not This property is not important for ntsec so in this document the difference between SDs and SAs is ignored 2 4 2 Process privileges Any process started under control of Cygwin has a semaphore attached to it that is used for signaling purposes The creation of this semaphore can be found in sigproc cc function getsem The fi
111. s with Cygwin http cygwin com problems html 2 2 Environment Variables Before starting bash you may set some environment variables A bat file is provided where the most important ones are set before bash in launched This is the safest way to launch bash initially The bat file is installed in the root directory that you specified during setup and pointed to in the Start Menu under the Cygwin option You can edit it this file your liking The CYGWIN variable is used to configure many global settings for the Cygwin runtime system Initially you can leave CYGWIN unset or set it to tty e g to support job control with Z etc using a syntax like this in the DOS shell before launching bash C gt set CYGWIN tty notitle glob 13 Chapter 2 Setting Up Cygwin The PATH environment variable is used by Cygwin applications as a list of directories to search for executable files to run This environment variable is converted from Windows format e g C WinNTNsystem32 C WinNT to UNIX format e g WinNT system32 WinNT when a Cygwin process first starts Set it so that it contains at least the x cygwin bin directory where x cygwin is the root of your cygwin installation if you wish to use cygwin tools outside of bash The HOME environment variable is used by many programs to determine the location of your home directory and we recommend that it be defined This environment variable is also converted from Windows format when
112. s you should either unset MAILCHECK or define MAILPATH to point to your existing mail inbox bashrcis similar to profile butis executed each time an interactive bash shell is launched It serves to define elements that are not inherited through the environment such as aliases If you do not use login shells you may want to put the contents of profile as discussed above in this file instead 28 Chapter 2 Setting Up Cygwin shopt s nocaseglob will allow bash to glob filenames in a case insensitive manner Note that bashrc is not called automatically for login shells You can source it from profile inputrc controls how programs using the readline library including bash behave It is loaded automatically For full details see the Function and Variable Index section of the GNU readline manual Consider the following settings f Ignore case while completing set completion ignore case on Make Bash 8bit clean set meta flag on set convert meta off set output meta on The first command makes filename completion case insensitive which can be convenient in a Windows environment The next three commands allow bash to display 8 bit characters useful for languages with accented characters Note that tools that do not use readline for display such as less and ls require additional settings which could be put in your bashrc alias less bin less r alias ls bin ls F color tty show control chars 29 C
113. sage information and exit n noname display user and group IDs instead of names v version output version information and exit 49 Chapter 3 Using Cygwin When multiple files are specified on the command line a blank line separates the ACLs for each file For each argument that is a regular file special file or directory getfacl displays the owner the group and the ACL For directories getfacl displays additionally the default ACL With no options specified getfacl displays the filename the owner the group and both the ACL and the default ACL if it exists For more information on Cygwin and Windows ACLs see see Section 2 4 in the Cygwin User s Guide The format for ACL output is as follows file filename owner name or uid group name or uid user perm user name or uid perm group perm group name or gid perm mask perm other perm default user perm default user name or uid perm default group perm default group name or gid perm default mask perm default other perm 3 7 5 kill Usage kill f signal s signal pidl pid2 kill 1 signal Send signals to processes f force force using win32 interface if necessary lye Srst print a list of signal names S signal send signal use kill list for a list h help output usage information and exit v version output version information and exit The kill program allows you to send arbitrary signals to other Cygwin
114. section gives the design goals a If the filename is specified as a POSIX path and it appears to reside on a file system that is mounted i e if its pathname starts with a directory displayed by mount then the default is specified by the mount flag If the file is a symbolic link the mode of the target file system applies 32 Chapter 3 Using Cygwin b If the file is specified via a MS DOS pathname i e it contains a backslash or a colon the default is binary c Pipes and non file devices are opened in binary mode except if the CYGWIN environment variable contains nobinmode Warning In b20 1 of 12 98 a file will be opened in binary mode if any of the following conditions hold 1 binary mode is specified in the open call 2 the filename is a MS DOS filename 3 the file resides on a binary mounted partition 4 CYGWIN contains binmode 5 the file is not a disk file d When redirecting the Cygwin shells uses rules a e For these shells the relevant value of CYGWIN is that at the time the shell was launched and not that at the time the program is executed Non Cygwin shells always pipe and redirect with binary mode With non Cygwin shells the commands cat filename program and program filename are not equivalent when ilename is on a text mounted partition 3 2 3 Example To illustrate the various rules we provide scripts to delete CRs from files by using the tr program which can only write to standard ou
115. sed to gain this functionality differs A trivial example in our implementation of uname the library examines the sysinfo dwProcessorType structure member to figure out the processor type under Windows 9x This field is not supported in NT which has its own operating system specific structure member called sysinfo wProcessorLevel Other differences between NT and 9x are much more fundamental in nature The best example is that only NT provides a security model 1 6 3 Permissions and Security Windows NT includes a sophisticated security model based on Access Control Lists ACLs Cygwin maps Win32 file ownership and permissions to the more standard older UNIX model by default Cygwin version 1 1 introduces support for ACLs according to the system calls used on newer versions of Solaris This ability is used when the ntsec feature is switched on which is described in another chapter The chmod call maps UNIX style permissions back to the Win32 equivalents Because many programs Chapter 1 Cygwin Overview expect to be able to find the etc passwd and etc group files we provide utilities that can be used to construct them from the user and group information provided by the operating system Under Windows NT the administrator is permitted to chown files There is no mechanism to support the setuid concept or API call since Cygwin version 1 1 2 With version 1 1 3 Cygwin introduces a mechanism for setting real and effective UIDs under Win
116. ser and system mount points and cygdrive prefixes o options X X Specify mount options p show cygdrive prefix show user and or system cygdrive path prefix s system default add system wide mount point t text text files get r n line endings u user add user only mount point v version output version information and exit X executable treat all files under mount point as executables E no executabl treat all files under mount point as non executables X cygwin executable treat all files under mount point as cygwin executables The mount program is used to map your drives and shares onto Cygwin s simulated POSIX directory tree much like as is done by mount commands on typical UNIX systems Please see Section 3 1 2 for more information on the concepts behind the Cygwin POSIX file system and strategies for using mounts To remove mounts use umount 54 Chapter 3 Using Cygwin 3 7 8 1 Using mount If you just type mount with no parameters it will display the current mount table for you Example 3 9 Displaying the current set of mount points cygwin gt mount cygwin bin on usr bin type system binmode cygwin lib on usr lib type system binmode cygwin on type system binmode on c type user binmode noumount CO Qj cQ 0 Qs 0 on d type user binmode noumount In this example c cygwin is the POSIX root and D drive is mapped to d Note that in this case the root mou
117. service It provides Cygwin applications with services which require security arbitration or which need to persist while no other cygwin application is running The implemented services so far are Control slave tty pty handle dispersal from tty owner to other processes without compromising the owner processes security XSIIPC Message Queues XSIIPC Semaphores XSI IPC Shared Memory 4l Chapter 3 Using Cygwin 3 6 2 Cygserver command line options Options to Cygserver take the normal UNIX style X or longoption form Nearly all options have a counterpart in the configuration file see below so setting them on the command line isn t really necessary Command line options override settings from the Cygserver configuration file The one character options are prepended by a single dash the long variants are prepended with two dashes Arguments to options are marked in angle brackets below These are not part of the actual syntax but are used only to denote the arguments Note that all arguments are required Cygserver has no options with optional arguments The recognized options are f config file file Use file as configuration file instead of the default configuration line The default configuration file is letc cygserver conf typically The help and version options will print the default configuration pathname This option has no counterpart in the configuration file for obvious reasons
118. set Cygwin handles file permissions so that the parent directories permissions are checked as it s default on POSIX systems If not set only the file s own permissions are taken into account This is the default on Windows and called bypass traverse checking Default was traverse in version 1 5 13 and 1 5 14 Beginning with 1 5 15 traverse checking is disabled again since it s not correctly implemented by Microsoft and it s behaviour is getting worse with each new OS version Unprivileged terminal server sessions are practically impossible with traverse checking switched on So use at your own risk noJtty if set Cygwin enables extra support i e termios for UNIX like ttys in the Windows console It is not compatible with some Windows programs Defaults to not set in which case the tty is opened in text mode Note that this has been changed such that D works as expected instead of Z and is settable via stty This option must be specified before starting a Cygwin shell and it cannot be changed in the shell It should not be set when using other terminals i e rxvt or xterm no winsymlinks if set Cygwin creates symlinks as Windows shortcuts with a special header and the R O attribute set If not set Cygwin creates symlinks as plain files with a magic number a path and the system attribute set Defaults to set 3 6 Cygserver 3 6 1 What is Cygserver Cygserver is a program which is designed to run as a background
119. shows the basics of UNIX like setting of file permissions NT SIDs in Cygwin talks about using SIDs in etc passwd and etc group The mapping leak illustrates the permission mapping leak of Windows NT The ACL API describes in short the ACL API since release 1 1 New setuid concept describes the new support of a setuid concept introduced with release 1 1 3 Switching User Context gives the basics of using the SYSTEM user to switch user context 15 Chapter 2 Setting Up Cygwin Special values of user and group ids explains the way Cygwin shows users and groups that are not in etc passwd or etc group 2 4 1 NT security The NT security allows a process to allow or deny access of different kind to objects Objects are files processes threads semaphores etc The main data structure of NT security is the security descriptor SD structure It explains the permissions that are granted or denied to an object and contains information that is related to so called security identifiers SID A SID is a unique identifier for users groups and domains SIDs are comparable to UNIX UIDs and GIDs but are more complicated because they are unique across networks Example SID of a system foo 1 5 21 165875785 1005667432 441284377 SID of a user johndoe of the system foo 1 5 21 165875785 1005667432 441284377 1023 The above example shows the convention for printing SIDs The leading S shou
120. slation is normally only used when trying to derive the POSIX equivalent current directory Otherwise the handling of MS DOS filenames bypasses the mount table Invoking mount without any arguments displays Cygwin s current set of mount points In the following example the C drive is the POSIX root and D drive is mapped to d Note that in this case the root mount is a system wide mount point that is visible to all users running Cygwin programs whereas the d mount is only visible to the current user Example 3 1 Displaying the current set of mount points gt mount cygwin bin on usr bin type system binmode cygwin lib on usr lib type system binmode cygwin on type system binmode Nsrc on usr src type system binmode on cygdrive c type user binmode noumount D Q D th FH Hh Q on cygdrive e type user binmode noumount You can also use the mount command to add new mount points and the umount to delete them See Section 3 7 8 and Section 3 7 15 for more information on how to use these utilities to set up your Cygwin POSIX file system Whenever Cygwin cannot use any of the existing mounts to convert from a particular Win32 path to a POSIX one Cygwin will automatically default to an imaginary mount point under the default POSIX path cygdrive For example if Cygwin accesses Z foo and the Z drive is not currently in the mount table then z would be automatically converted to cygdrive z The default prefi
121. ssage if no filename argument was given It can be used in make file rules converting variables that may be omitted to a proper format Note that cygpath output may contain spaces C Program Files so should be enclosed in quotes Example 3 4 Example cygpath usage bin sh if fij e j then XPATH else XPATH cygpath w S 1 ET explorer XPATH amp The capital options D H P S and w output directories used by Windows that are not the same on all systems for example s might output C WINNT S YSTEM32 or C WINDOWS SYSTEM The H shows the Windows profiles directory that can be used as root of home The A option forces use of the All Users directories instead of the current user for the D and P options On Win9x systems with 48 Chapter 3 Using Cygwin only a single user A has no effect D and AD would have the same output By default the output is in UNIX POSIX format use the w or d options to get other formats 3 7 3 dumper Usage dumper OPTION FILENAME WIN32PID Dump core from WIN32PID to FILENAME core d verbos be verbose while dumping h help output help information and exit q quiet be quiet while dumping default v version output version information and exit The dumper utility can be used to create a core dump of running Windows process This core dump can be later loaded to gdb and analyzed One common way to use dumper is to plu
122. t it only contains the tiny bit of information needed to tell the OS how your program interacts with imports the dll This information is linked into your exe This is also generated by d11too1 4 3 1 Building DLLs This page gives only a few simple examples of gcc s DLL building capabilities To begin an exploration of the many additional options see the gcc documentation and website currently at http gcc gnu org Let s go through a simple example of how to build a dll For this example we ll use a single file myprog c for the program myprog exe and a single file myd11 c for the contents of the dll mydll dll Fortunately with the latest gcc and binutils the process for building a dll is now pretty simple Say you want to build this minimal function in mydll c include lt stdio h gt int hello printf Hello World n First compile mydll c to object code gcc c mydll c 75 Chapter 4 Programming with Cygwin Then tell gcc that it is building a shared library gcc shared o mydll dll mydll o That s it To finish up the example you can now link to the dll with a simple program int main hello Then link to your dll with a command like gcc o myprog myprog ca L lmydll However if you are building a dll as an export library you will probably want to use the complete syntax gcc shared o cyg module dll W1 out implib lib module dll a Wl xport all symbol
123. tput The script bin sh Remove r from the file given as argument tr ad AP Sp SUS ocr will not work on a text mounted systems because the V will be reintroduced on writing However scripts such as bin sh Remove r from the file given as argument tr d Nr gzip gunzip gt I nocr and the bat file 33 Chapter 3 Using Cygwin REM Remove r from the file given as argument echo off tr d r lt 1 gt 1 nocr work fine In the first case assuming the pipes are binary we rely on gunzip to set its output to binary mode possibly overriding the mode used by the shell In the second case we rely on the DOS shell to redirect in binary mode 3 2 4 Binary or text UNIX programs that have been written for maximum portability will know the difference between text and binary files and act appropriately under Cygwin For those programs the text mode default is a good choice Programs included in official Cygwin distributions should work well in the default mode Text mode makes it much easier to mix files between Cygwin and Windows programs since Windows programs will usually use the CRLF format Unfortunately you may still have some problems with text mode First some of the utilities included with Cygwin do not yet specify binary mode when they should Second you will introduce CRs in text files you write which can cause problems when moving them back to a UNIX system If you are mounting a remote fil
124. un and run objdump like this objdump h cygwinl dll It will print a report like this cygwinl dll file format pei i386 Sections Idx Name Size VMA LMA File off Algn 0 text 0007ea00 61001000 61001000 00000400 2 2 CONTENTS ALLOC LOAD READONLY CODE DATA 1 data 00008000 61080000 61080000 0007ee00 2 2 CONTENTS ALLOC LOAD DATA The only information we re concerned with are the VMA of the text section and the VMA of the section after it sections are usually contiguous you can also add the Size to the VMA to get the end address In this case the VMA is 0x61001000 and the ending address is either 0x61080000 start of data method or 0x0x6107fa00 VM A Size method There are two basic ways to use SSP either profiling a whole program or selectively profiling parts of the program To profile a whole program just run ssp without options By default it will step the whole program Here s a simple example using the numbers above ssp 0x61001000 0x61080000 hello exe This will step the whole program It will take at least 8 minutes on a PII 300 yes really When it s done it will create a file called gmon out You can turn this data file into a readable report with gprof gprof b cygwinl dll The b means skip the help pages You can omit this until you re familiar with the report layout The gprof documentation explains a lot about this report but ssp changes a few
125. use ntsec on remote drives as well default is nosmbntesc When setting smbntsec there s a chance that you get problems with Samba shares so you should use this option with care One reason for a non working ntsec on remote drives could be insufficient permissions of the users The requires user rights are somewhat dangerous SeRestorePrivilege so it s not always an option to grant that rights to users However this shouldn t be a problem in NT domain environments no reset com if set serial ports are reset to 9600 8 N 1 with no flow control when used This is done at open time and when handles are inherited Defaults to set no server if set allows client applications to use the Cygserver facilities This option must be enabled explicitely on the client side otherwise your applications won t be able to use the XSI IPC 40 Chapter 3 Using Cygwin function calls nsgget semget shmget and friends successfully These function calls will return with ENOSYS Bad system call no strip title if set strips the directory part off the window title if any Default is not set no title if set the title bar reflects the name of the program currently running Default is not set Note that under Win9x the title bar is always enabled and it is stripped by default but this is because of the way Win9x works In order not to strip specify title ortitle nostrip title noJtraverse This option only affects NT systems If
126. utils Another problem area is between Unix style links which link one file to another and Microsoft Ink files which provide a shortcut to a file They seem similar at first glance but in reality are fairly different By default Cygwin uses a mechanism that creates symbolic links that are compatible with standard Microsoft Ink files However they do not include much of the information that is available in a standard Microsoft shortcut such as the working directory an icon etc The cygutils package includes a mkshortcut utility for creating standard Microsoft Ink files If Cygwin handled these native shortcuts like any other symlink you could not archive Microsoft Ink files into tar archives and keep all the information in them After unpacking these shortcuts would have lost all the extra information and would be no different than standard Cygwin symlinks Therefore these two types of links are treated differently Unfortunately this means that the usual Unix way of creating and using symlinks does not work with Windows shortcuts 3 8 6 Printing with cygutils There are several options for printing from Cygwin including the Ipr found in cygutils not to be confused with the native Windows Ipr exe The easiest way to use cygutils Ipr is to specify a default device name in the PRINTER environment variable You may also specify a device on the command line with the d or P options which will override the environment variable setting
127. x of cygdrive may be changed see the Section 3 7 8 for more information It is possible to assign some special attributes to each mount point Automatically mounted partitions are displayed as auto mounts Mounts can also be marked as either textmode or binmode whether text files are read in the same manner as binary files by default or not see Section 3 2 for more information on text and binary modes 3 1 3 Additional Path related Information The cygpath program provides the ability to translate between Win32 and POSIX pathnames in shell scripts See Section 3 7 2 for the details 3l Chapter 3 Using Cygwin The HOME PATH and LD LIBRARY PATH environment variables are automatically converted from Win32 format to POSIX format e g from c cygwin bin to bin if there was a mount from that Win32 path to that POSIX path when a Cygwin process first starts Symbolic links can also be used to map Win32 pathnames to POSIX For example the command In s pollux home joe data data would have about the same effect as creating a mount point from pollux home joe data to data using mount except that symbolic links cannot set the default file access mode Other differences are that the mapping is distributed throughout the file system and proceeds by iteratively walking the directory tree instead of matching the longest prefix in a kernel table Note that symbolic links will only work on network drives that are properly configured

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