Home

Excerpts from “The Linux Users` Guide”

1. Once it s returned to the foreground the y s will start coming again as fast as before You do not need to worry that while you had it suspended it was storing up more y s to send to the screen when a program is suspended the whole program doesn t run until you bring it back to life Now type ctrl c to kill it for good once you ve seen enough Let s pick apart that message we got from the shell 1 Stopped yes The number in brackets is the job number of this job and will be used when we need to refer to it specifically Naturally since job control is all about running multiple processes we need some way to tell one from another The following it tells us that this is the current job that is the one most recently moved from the foreground to the background If you were to type fg you would put the job with the in the foreground again More on that later when we discuss running multiple jobs at once The word Stopped means that the job is stopped The job isn t dead but it isn t running right now LINUX has saved it in a special suspended state ready to jump back into the action should anyone request it Finally the yes is the name of the process that has been stopped Before we go on let s kill this job and start it again in a different way The command is named kill and can be used in the following way home larry kill 1 1 Stopped yes home larry That message a
2. Tm going to list a few more commands now along with the ones you ve learned already and you can practice them however you like Pd suggest becoming familiar with them before going any further cC Move forward one character Move backward one character Go to next line Go to previous line Go to beginning of line Go to end of line Go to next page screenful of text Redraw the screen with current line in center Delete this character practice this one Delete text from here to end of line x C s Save the buffer in its corresponding file ee PG Gara Oo FAarPdoOPpPUB OM Backspace Delete preceding character the one you just typed 4 2 Getting Started Quickly in X Tf all you re interesting in is editing a few files quickly an X user doesn t have to go much further beyond the menus at the top of the screen fers Files Tools Edit Search Help These menus are not available in text mode When you first start Emacs there will be four menus at the top of the screen Buffers File Edit and Help To use a menu simply move the mouse pointer over the name like File click and hold down on the left button Then move the pointer to the action you want and release the mouse button If you change your mind move the mouse pointer away from the menu and release the button The Buffers menu lists the different files you ve been editing in this incarnation of Emacs The File menu shows a bunch of commands for l
3. e1 as in c mode el However to make Lisp code run faster Emacs allows it to be byte compiled and these files of compiled Lisp code end in elc instead of el The exception to this is your emacs file which does not need the el extension because Emacs knows to search for it on startup To load a file of Lisp code interactively use the command M x load file It will prompt you for the name of the file To load Lisp files from inside other Lisp files do this load c mode force Emacs to load the stuff in c mode el or elc Emacs will first add the elc extension to the filename and try to find it somewhere in the load path If it fails it tries it with the el extension failing that it uses the literal string as passed to load You can byte compile a file with the command M x byte compile file but if you modify the file often it s probably not worth it You should never byte compile your emacs though nor even give it a el extension After your emacs has been loaded Emacs searches for a file named default e1 to load Usually it s located in a directory in load path called site lisp or local elisp or something see the example load path I gave a while ago People who maintain Emacs on multi user systems use default el to make changes that will affect everyone s Emacs since everybody s Emacs loads it after heir personal emacs Default e1 should not be byte compiled either since it tends to be mod
4. fg the primary foreground color xterm fg yellow bg the primary background color xterm bg blue e The number of the server running on that machine Since any one machine could have multiple X servers running on it unlikely for most LINUX machines but possible each must have a unique number e The screen number X supports a particular server controlling more than one screen at a time You can imagine that someone wants a lot of screen space so they have two monitors sitting next to each other Since they don t want two X servers running on one machine for performance reasons they let one X server control both screens These three things are put together like so machine server number screen number For instance on mousehouse all my applications have the display set to 0 0 which means the first screen of the first server on the local display However if I am using a remote computer the display might be set to mousehouse 0 0 By default the display is taken from the environment variable see Section named DISPLAY and can be overridden with a command line option see Figure 2 2 To see how DISPLAY is set try the command echo DISPLAY 2 6 Common Features While X is a graphical user interface it is a very uneven graphical user interface It s impossible to say how any component of the system is going to work because every component can easily be reconfigured changed and even replaced This means it
5. s hard to say exactly how to use various parts of the interface We ve already encountered one cause of this the different window managers and how configurable each window manager is Another cause of this uneven interface is the fact that X applications are built using things called widget sets Included with the standard X distribution are Athena widgets developed at MIT These are commonly used in free applications They have the disadvantage that they are not particularly good looking and are somewhat harder to use than other widgets The other popular widget set is called Motif Motif is a commercial widget set similar to the user interface used in Microsoft Windows Many commercial applications use Motif widgets as well as some free applications The popular World Wide Web Browser netscape uses Motif Let s try to go through some of the more usually things you ll encounter 2 6 1 Buttons Buttons are generally the easiest thing to use A button is invoked by positioning the mouse cursor over it and clicking pressing and immediately releasing the mouse button the left button Athena and Motif buttons are functionally the same although they have cosmetic differences 2 6 2 Menu Bars A menu bar is a collection of commands accessible using the mouse For instance emacs s menu bar is shown in Figure 2 3 Each word is a category heading of commands File deals with commands 20 Chapter 2 The X Window System Fig
6. The Unix Shell 1 3 2 The Current Directory and cd pwd Using directories would be cumbersome if you had to type the full path each time you wanted to access a directory Instead Unix shells have a feature called the current or present or working directory Your setup most likely displays your directory in your prompt home larry If it doesn t try the command pwd for present working directory Sometimes the prompt will display the machine name This is only really useful in a networked environment with lots of different machines mousehouse gt pwd home larry mousehouse gt cd directory As you can see pwd tells you your current directory a very simple command Most commands act by default on the current directory For instance 1s without any parameters displays the contents of the current directory We can change our current directory using cd For instance try home larry cd home home 1s F larry sam shutdown steve user1 homett If you omit the optional parameter directory you re returned to your home or original directory Otherwise cd will change you to the specified directory For instance home cd home larry cd cd home homett cd usr usr cd local bin usr local bin As you can see cd allows you to give either absolute or relative pathnames An absolute path starts with and specifies all the directories before the one you wanted A relative p
7. Emacs sala a ara a A 43 dle Finding Qui More Cora e ar a a a A 46 CONTENTS Chapter 1 The Unix Shell Making files is easy under the UNIX operating system Therefore users tend to create numerous files using large amounts of file space It has been said that the only standard thing about all UNIX systems is the message of the day telling users to clean up their files System V 2 administrator s guide 1 1 Unix Commands When you first log into a Unix system you are presented with something that looks like the following home larry That something is called a prompt As its name would suggest it is prompting you to enter a command Every Unix command is a sequence of letters numbers and characters There are no spaces however Some valid Unix commands are mail cat and CMU_is_Number 5 Some characters aren t allowed we ll go into that later Unix is also case sensitive This means that cat and Cat are different commands The prompt is displayed by a special program called the shell Shells accept commands and run those commands They can also be programmed in their own language and programs written in that language are called shell scripts There are two major types of shells in Unix Bourne shells and C shells Bourne shells are named after their inventor Steven Bourne Steven Bourne wrote the original Unix shell sh and most shells since then end in the letters sh to indicate they are extentions on the original
8. There s about one full page of information about cat Try running man now Don t expect to understand the manpage given Manpages usually assume quite a bit of Unix knowledge knowledge hat you might not have yet When you ve read the page there s probably a little black block at the bottom of your screen similar to more or Line 1 This is the more prompt and you ll learn to love it Instead of just letting the text scroll away man stops at the end of each page waiting for you o decide what to do now If you just want to go on press Space and you ll advance a page If you want to exit quit the manual page you are reading just press q You ll be back at the shell prompt and it ll be waiting for you to enter a new command There s also a keyword function in man For example say you re interested in any commands hat deal with Postscript the printer control language from Adobe Type man k ps or man k Postscript you ll get a listing of all commands system calls and other documented parts of Unix hat have the word ps or Postscript in their name or short description This can be very useful when you re looking for a tool to do something but you don t know it s name or if it even exists 1 3 Storing Information Filters are very useful once you are an experienced user but they have one small problem How do you store the information Surely you aren t
9. change how the mouse cursor looks when it is moved over them that is probably the method used to resize windows Another method used is to create a resizing button on the titlebar In Figure 2 3 a small button is visible on the right of each titlebar To resize windows the mouse is moved onto the resize button and the left mouse button is held down You can then move the mouse outside the borders of the window to resize it The button is released when the desired size has been reached 2 4 7 Maximization Most window managers support maximization In twm for instance you can maximize the height the width or both dimensions of a window This is called zooming in twm s language although I prefer the term maximization Different applications respond differently to changes in their window size For instance xterm won t make the font bigger but will give you a larger workspace Unfortunately it is extremely non standard on how to maximize windows 18 Chapter 2 The X Window System 2 4 8 Menus Another purpose for window managers is for them to provide menus for the user to quickly accomplish tasks that are done over and over For instance I might make a menu choice that automatically launches Emacs or an additional xterm for me That way I don t need to type in an xterm an especially good thing if there aren t any running xterms that I need to type in to start a new program In general different menus can be ac
10. could have typed M x fundamental mode to make it so All mode names have a command called lt modename gt mode which puts the current buffer into that mode Then to find out more information about that major mode I typed C h m which gets you help on the current major mode of the buffer you re in There s a slightly more useful mode called text mode which has the special commands M S for center paragraph and M s which invokes center line M S by the way means exactly what you think it does hold down both the Meta and the Shift key and press S Don t just take my word for this go make a new buffer put it into text mode and type C h m You may not understand everything Emacs tells you when you do that but you should be able to get some useful information out of it Here is an introduction to some of the more commonly used modes If you use them make sure that you type C h m sometime in each one to find out more about each mode 7To make matters worse there are Major Modes and Minor Modes but you don t need to know about that right now SRichard Stallman also sometimes referred to as rms because that s his login name 4 11 Programming Modes 41 4 11 Programming Modes 4 11 1 C Mode If you use Emacs for programming in the C language you can get it to do all the indentation or you automatically Files whose names end in c or h are auto
11. has no effect Clicking the left button above the current position scrolls upward Similarly clicking below the current position scrolls downward Clicking and holding the left button on the current position allows one to move the bar at will Releasing the left button positions the window Clicking the middle button anywhere on the bar will immediately jump to that location similar to the behavior of the Athena middle button However instead of starting to display the data at the position clicked that position is taken to be the midpoint of the data to be displayed 22 Chapter 2 The X Window System Chapter 3 Working with Unix A UNIX saleslady Lenore Enjoys work but she likes the beach more She found a good way To combine work and play She sells C shells by the seashore Unix is a powerful system for those who know how to harness its power In this chapter PI try to describe various ways to use Unix s shell bash more efficently 3 1 Wildcards In the previous chapter you learned about the file maintence commands cp mv and rm Occasionally you want to deal with more than one file at once in fact you might want to deal with many files at once For instance you might want to copy all the files beginning with data into a directory called backup You could do this by either running many cp commands or you could list every file on one command line Both of these methods would take a long time however and yo
12. idea There are many implementations of his shell and all those specific shell programs are called Bourne shells Another class of shells C shells originally implemented by Bill Joy are also common Traditionally Bourne shells have been used for shell scripts and compatibility with the original sh while C shells have been used for interactive use C shells have had the advantages of having better interactive features but somewhat harder programming features LINUX comes with a Bourne shell called bash written by the Free Software Foundation bash stands for Bourne Again Shell one of the many bad puns in Unix It is an advanced Bourne shell it contains the standard programming features found in all Bourne shells with many interactive features commonly found in C shells bash is the default shell to use running LINUX When you first login the prompt is displayed by bash and you are running your first Unix program the bash shell As long as you are logged in the bash shell will constantly be running 1Case sensitivity is a very personal thing Some operating systems such as OS 2 or Windows NT are case preserving but not case sensitive In practice Unix rarely uses the different cases It is unusual to have a situation where cat and Cat are different commands 4 Chapter 1 The Unix Shell 1 1 1 A Typical Unix Command The first command to know is cat To use it type cat and then return home la
13. make the right edge of the window fifty pixels from the right edge of the screen It s generally impossible to start the window off the screen although a window can be moved off the screen The main exception is when the window is very large e The vertical distance from either the top or the bottom A positive vertical distance is measured from the top of the screen a negative vertical distance is measured from the bottom of the screen All four components get put together into a geometry string that looks like 503x73 78 0 That translates into a window 503 pixels long 73 pixels high put near the top right hand corner of the screen Another way of stating it is hsizexvsize hplace vplace 2 5 2 Display Every X application has a display that it is associated with The display is the name of the screen that the X server controls A display consists of three components e The machine name that the server is running on At stand alone LINUx installations the server is always running on the same system as the clients In such cases the machine name can be omitted 4One fun program to try is called xfishtank It places a small aquarium in the background for you 2 6 Common Features 19 Figure 2 2 Standard options for X programs Name Followed by Example geometry geometry of the window xterm geometry 80x24 0 90 display display you want the program to appear xterm display lionsden 0 0
14. of clicking or typing in xclock s window will affect it that s all it does Or is it In fact there are various different options you can give to the program to have it act in different ways For instance xclock digital will create a digital clock xclock update 1 will create a second hand that moves every second while update 5 will create a second hand that moves every 5 seconds For more information on xclock s options consult its manpage man xclock If you re going to try running a few of your own xclocks you should probably read Section 3 4 Multitasking to learn how to run them in addition to your current programs If you run an xclock in the foreground the usual way of running a program and want to get out of it type ctrl c There are several acceptable ways to refer to The X Window System A common though incorrect way of referring to X is X Windows 2 4 Window Managers 15 Figure 2 1 An annotated example of a standard X screen In this example the user is running twm The standard clock has been replaced by a transparent clock called oclock icon manager peering E a s iada na A ma anas Te IL rara de ml een Ll A E pS ca do a a ic ee a root menu Tiin m er e re mei es eri 2 3 2 XTerm The window with a prompt in it something that probably looks like home larry is being con trolled by a program called xterm xterm is a deceptively complicated program
15. or the paste buffer There s another way to do cutting and pasting whenever you use C k to kill to the end of a line the killed text is saved in the kill ring If you kill more than one line in a row they are all saved in the kill ring together so that the next yank will paste in all the lines at once Because of this feature it is often faster to use repeated C k s to kill some text than it is to explicitly set mark and 4Occasionally even one C g isn t enough to persuade Emacs that you really wanted to interrupt what you re doing Just keep at it and Emacs will usually return to a saner mode 5On some terminals C SPC doesn t work For these machines you must use C 38 Chapter 4 Editing files with Emacs point and use C w However either way will work It s really a matter of personal preference how you do it 4 7 Searching and Replacing There are several ways to search for text in Emacs Many of them are rather complex and not worth going into here The easiest and most entertaining way is to use isearch Isearch stands for incremental search Suppose you want to search for the string gadfly in the following buffer I was growing afraid that we would run out of gasoline when my passenger exclaime Gadzooks There s a gadfly in here You would move to the beginning of the buffer or at least to some point that you know is before the first occurence of the goal wor
16. redirecting standard output it is also possible to redirect standard input Instead of a program reading from your keyboard it will read from a file Since input redirection is related to output redirection it seems natural to make the special character for input redirection be lt It too is used after the command you wish to run This is generally useful if you have a data file and a command that expects input from standard input Most commands also let you specify a file to operate on so lt isn t used as much in day to day operations as other techniques 3For impatient readers the command you might want to try is more However there s still a bit more to talk about before we get there 3 4 Multitasking 27 3 3 4 The Pipe Many Unix commands produce a large amount of information For instance it is not uncommon for a command like 1s usr bin to produce more output than you can see on your screen In order for you to be able to see all of the information that a command like 1s usr bin it s necessary to use another Unix command called more more will pause once every screenful of information For instance more lt etc rc will display the file etc rc just like cat etc rc would except that more will let you read it more also allows the command more etc rc and that s the normal way of invoking it However that doesn t help the problem that 1s usr bin displays more information than you can see more lt 1s usr bin w
17. sequence invokes it then use C h w for where is and type in the name of the function Or if you want to know what a function does in detail use C h f which prompts for a function name Remember since Emacs does completion on function names you don t really have to be sure what a function is called to ask for help on it If you think you can guess the word it might start SWe call C q a key even though it is produced by holding down Control and pressing q because it is a single ASCII character 40 Chapter 4 Editing files with Emacs with type that and hit Tab to see if it completes to anything If not back up and try something else The same goes for file names even if you can t remember quite what you named some file that you haven t accessed for three months you can guess and use completion to find out if you re right Get used to using completion as means of asking questions not just as a way of saving keystrokes There are other characters you can type after C h and each one gets you help in a different way The ones you will use most often are C h k C h w and C h f Once you are more familiar with Emacs another one to try is C h a which prompts you for a string and then tells you about all the Un functions who have that string as part of their name the a means for apropos or about Another source of information is the Info documentation r
18. shell command just lists information about the jobs currently running or sus pending Sometimes it also tells you about ones that have just exited or been terminated ctrl c This is the generic interrupt character Usually if you type it while a program is running in the foreground it will kill the program sometimes it takes a few tries However not all programs will respond to this method of termination ctrl z This key combination usually causes a program to suspend although a few programs ignore it Once suspended the job can be run in the background or killed 3 4 2 The Theory of Job Control It is important to understand that job control is done by the shell There is no program on the system called fg rather fg bg amp jobs and kill are all shell builtins actually sometimes ki11 is an independent program but the bash shell used by Linux has it built in This is a logical way to do it since each user wants their own job control space and each user already has their own shell it is easiest to just have the shell keep track of the user s jobs Therefore each user s job numbers are meaningful only to that user my job number 1 and your job number 1 are probably two totally different processes In fact if you are logged in more than once each of your shells will have unique job control data so you as a user might have two different jobs with the same number running in two different shells The way to
19. still leaving us the prompt for interactive work The command to do that is bg home larry bg 1 yes gt dev null 4 home larry Now you ll have to trust me on this one after you typed bg yes gt dev null began to run again but this time in the background In fact if you do things at the prompt like 1s and stuff you might notice that your machine has been slowed down a little bit endlessly generating and discarding a steady stream of y s does take some work after all Other than that however there are no effects You can do anything you want at the prompt and yes will happily continue to sending its output into the black hole There are now two different ways you can kill it with the kill command you just learned or by putting the job in the foreground again and hitting it with an interrupt ctrl c Let s try the second way just to understand the relationship between fg and bg a little better home larry fg yes gt dev null now it s in the foreground again Imagine that I hit ctrl c to terminate it home larry There it s gone Now start up a few jobs running in simultaneously like this home larrytt yes gt dev null amp 1 1024 home larry yes sort gt dev null 2 1026 home larry yes uniq gt dev null and here type ctrl z to suspend it please 3 Stopped yes uniq gt dev null home larry The first thing you might notice about those commands
20. tell for sure is to use the Process ID numbers PID s These are system wide each process has its own unique PID number Two different users can refer to a process by its PID and know that they are talking about the same process assuming that they are logged into the same machine Let s take a look at one more command to understand what PIDs are The ps command will list all running processes including your shell Try it out It also has a few options the most important of which to many people are a u and x The a option will list processes belonging to any user not just your own The x switch will list processes that don t have a terminal associated with them Finally the u switch will give additionally information about the process that is frequently useful 6This only makes sense for certain system programs that don t have to talk to users through a keyboard 32 Chapter 3 Working with Unix To really get an idea of what your system is doing put them all together ps aux You can then see the process that uses the more memory by looking at the MEM column and the most CPU by looking at the CPU column The TIME column lists the total amount of CPU time used Another quick note about PIDs kill in addition to taking options of the form job will take options of raw PIDs So put a yes gt dev null in the background run ps and look for yes Then type kill PID If you start to program in C on your Linux sys
21. the program you tell it to run This raises an interesting question what happens if there are no files that meet the wildcard specification Try echo rc fr og and bash passes the wildcard specification verbatim to the program Other shells like tcsh will instead of just passing the wildcard verbatim will reply No match Here s the same command run under tcsh mousehouse gt echo rc fr og echo No match mousehouse gt The last question you might want to know is what if I wanted to have data echoed back at me instead of the list of file names Well under both bash and tcsh just include the string in quotes home larry report echo data mousehouse gt echo data data OR data home larry report mousehouse gt 3 1 2 The Question Mark In addition to the asterix the shell also interprets a question mark as a special character A question mark will match one and only one character For instance 1s etc will display all two letter files in the the etc directory 3 2 Time Saving with bash 3 2 1 Command Line Editing Occasionally you ve typed a long command to bash and before you hit return notice that there was a spelling mistake early in the line You could just delete all the way back and retype everything you need to but that takes much too much effort Instead you can use the arrow keys to move back there delete the bad character or two and type the correct information There are many special keys to help
22. was installed on your system common locations are usr lib emacs lisp usr lib emacs 19 19 lisp etc The 19 19 is the version number of Emacs and might be different on your system You don t need to poke around your filesystem looking for the lisp library because Emacs has the information stored internally in a variable called load path To find out the value of this variable it is necessary to evaluate it that is to have Emacs s lisp interpreter get its value There is a special mode for evaluating Lisp expressions in Emacs called lisp interaction mode Usually there is a buffer called scratch that is already in this mode If you can t find one create a new buffer of any name and type M x lisp interaction mode inside it Now you have a workspace for interacting with the Emacs Lisp interpreter Type this load path and then press C j at the end of it In lisp interaction mode C j is bound to eval print last sexp An sexp is an s expression which means a balanced group of parentheses including none Well that s simplifying it a little but you ll get a feel for what they are as you work with Emacs Lisp Anyway evaluating load path should get you something like this load path C j usr lib emacs site lisp vm 5 35 home kfogel elithp usr lib emacs site lisp usr lib emacs 19 19 lisp It won t look the same on every system of course since it is dependant on how Emacs was install
23. 044 4 ita Oa ee eG ee Ss 23 What s This On my Screen are bed oe ea eee bo eda och od DOM SOE A A BPG SIE oR ee ak F DBZ AM E Geers see Stead a Stee Me es ee tS ies Se A Bee ote ee eee a 2 4 Window Managers 2 4 oo fea enh doe o Pte ee a ae a Whe eee 2 4 1 When New Windows are Created o o o e 24 2 CEOCUS sont Pie Hal eat ee area e eis rape Gee E Bain E Stange Ge a 2 43 Moving Windows i sic get he ale et dey tales do teil aise epee 2 44 Depth 2 sonata be ete AR A BS a Bhs ZAS Teonizations 28 2 a Gam ao Pye Be A AS 2 46 2 Resizing a a deep A A ee Te ig Se eh ae Se he A ZAT Maximizar 2 cc A aoe OS ek dog 248 Menus iss tn da 868 ea Ge a Ons ns PSS Ata A Saye BS g DOS RAGGTID ULES rl AA a eh et tee Ee Bal Bt he 2L Geometry co gy E E pera dt ba had 4d thank Shed ob ve ele gta Meg 25022 Display RA SR AAA earns Bia i ek ee OE oe os 2 6 Common Features cid amp A dee eo Pee RE ESHA RY Ed a DG Whe BUCCONSS otic it og Beane E AA A MM NI 2 6 2 Menu Barts e dir A Ga es A ee ee a A Se en ede 26 3 Scroll Bargin se if fice cs Gel S28 ea Gu Wak Ohare BUA Gell Opa RDM eek So a iii CONTENTS 1 3 Working with Unix 23 34 Wildcards Fon se 20a A y ER A a 23 BL What Really Happens a si a eee ee ee EA A 23 3 1 2 The Question Mark 2 ani ss A el oe 24 3 2 Time Savine with Dago ei eto es Re o po RAE dede de 24 321 Command Line Editing sac 05 4 cs aa ase AA AA
24. 1 3 3 Terminated yes uniq gt dev null home larry jobs 1 Terminated yes gt dev null home larry You should see various messages about termination of jobs nothing dies quietly it seems Fig ure 3 1 on the facing page shows a quick summary of what you should know for job control 3 4 Multitasking 31 Figure 3 1 A summary of commands and keys used in job control fg job This is a shell command that returns a job to the foreground To find out which one this is by default type jobs and look for the one with the Parameters Optional job number The default is the process identified with amp When an amp is added to the end of the command line it tells the command to run in the background automatically This process is then subject to all the usual methods of job control detailed here bg job This is a shell command that causes a suspended job to run in the background To find out which one this is by default type jobs and look for the one with the Parameters Optional job number The default is the process identified with ki11 job PID This is a shell command that causes a background job either suspended or running to terminate You should always specify the job number or PID and if you are using job numbers remember to precede them with a Parameters Either the job number preceded by or PID no is necessary More than one process or job can be specified on one line jobs This
25. 24 3 2 2 Command and File Completion o o e e 25 3 3 The Standard Input and The Standard Output o o 25 3 3 1 Unix Concepts ranei A A A ER 25 3 3 2 ir A II 26 3 3 3 Input Redirection e oa da foe ss Ok ey cas A dd A 26 Genk RUE PIDs o T o u Ged ee rape bg a BE Sik Ob Bree aS 27 3 4 Multitasking lt 2 2 202 a 8 al Ok Pe ot es 27 Sad Usine dob Control a4 ds he sg A SAA A A ee ES 27 3 4 2 The Theory of Job Control 5 4 bo eee ee e ta red di 31 3 5 Virtual Consoles Being in Many Places at Once 2 0 32 4 Editing files with Emacs 33 Bol Whats Emas ua A lo Sede tag a Aad 33 4 2 Getting Started Quickly in 4 era u a Se eli BO a grele ey gy Gal Bes 35 4 3 Editing Many Files at Once 24 455 se ee Sw a a nS 35 44 Ending an Editing Session 64 3 4 06 AAA a ee A A A 36 4 5 The Meta Key gt cuide ca Bl pub td A a ias 37 46 Cutting Pasting Killing and Yanking 220 02 44 04 na tasas ds 37 amp T Searching and Hepla cite se Gap ahh ok Sagas We la SOE El Bu Ss 38 4 8 What s Really Going On Here o o ooo e e e 38 aD Asking Emacs Tor Help ga A AY A E A A A 39 4 10 Specializing Buffers Modes o eo e e e 40 4 11 Programming Modes ito apa a a 41 ALE Mods 0 e te a Sarat Wid Wg a ERA 41 LLL Scheme Modern EA ESA AA aa PA ER 41 AMAS MA Made te EA A EAS sie HE e AA 42 4 12 Being Even More Efficient oaoa 42 4 03 Customize
26. At first glance it doesn t seem to do much but it actually has to do a lot of work xterm emulates a terminal so that regular text mode Unix applications work correctly It also maintains a buffer of information so that you can refer back to old commands To see how to use this look at Section 2 6 3 For much of this book we re going to be learning about the Unix command line and you ll find that inside your xterm window In order to type into xterm you usually have to move your mouse cursor possibly shaped like an X or an arrow into the xterm window However this behavior is dependent on the window manager One way of starting more programs under X is through an xterm Since X programs are standard Unix programs they can be run from normal command prompts such as xterms Since running a long term program from a xterm would tie up the xterm as long as the program was running people normally start X programs in the background For more information about this see Section 3 4 2 4 Window Managers On LINUX there are two different window managers that are commonly used One of them called twm is short for Tab Window Manager It is larger than the other window manager usually used 16 Chapter 2 The X Window System fvwm fvwm stands for F Virtual Window Manager the author neglected to tie down exactly what the f stood for Both twm and fvwm are highly configurable which means I can t tell you exactly wh
27. Excerpts from The LINUX Users Guide Introductory Course on Scientific Programming International Master of Science Programme in Scientific Computing This is an excerpt from the LINUX Users Guide written by Larry Greenfield It covers basic Unix commands and is intended for the beginning Unix user The full guide can be downloaded from the home page of The Linux Documentation Project http metalab unc edu LDP UNIX is a trademark of X Open MS DOS and Microsoft Windows are trademarks of Microsoft Corporation OS 2 and Operating System 2 are trademarks of IBM X Window System is a trademark of X Consortium Inc Motif is a trademark of the Open Software Foundation LINUX is not a trademark and has no connection to UNIX Unix System Labratories or to X Or Please bring all unacknowledged trademarks to the attention of the author Copyright c Larry Greenfield 427 Harrison Avenue Highland Park NJ 08904 leg andrew cmu edu Permission is granted to make and distribute verbatim copes of this manual provided the copyri notice and this permission notice are preserved on all copies Permission is granted to copy and distribute modified versions of this manual under the conditions verbatim copying provided also that the sections that reprint The GNU General Public Licen The GNU Library General Public License and other clearly marked sections held under sepe copyright are reproduced under the conditions given withi
28. a time they always keep their short name This leads to an interesting question What if I type cp frog passwd toad where frog and passwd exist and toad isn t a directory Try it and see 1 4 2 Pruning Back with rm rm i filel file2 fileN Now that we ve learned how to create millions of files with cp and believe me you ll find new ways to create more files soon it may be useful to learn how to delete them Actually it s very simple the command you re looking for is rm and it works just like you d expect any file that s a parameter to rm gets deleted For example home larry ls F frog passwd passwd_version home larry rm frog toad passwd rm toad No such file or directory home larry ls F passwd_version home larry SLOW 12 Chapter 1 The Unix Shell As you can see rm is extremely unfriendly Not only does it not ask you for confirmation but it will also delete things even if the whole command line wasn t correct This could actually be dangerous Consider the difference between these two commands home larry ls F toad frog home larry ls F frog toad home larry rm frog toad home larry and this home larry rm frog toad rm frog is a directory home larry ls F frog home larry As you can see the difference of one character made a world of difference in the outcome of the command It is vital that you check your command lines before hitting re
29. ace of course You should see the message Mark set appear in the minibuffer The mark has now been set at that place There will be no special highlighting indicating that fact but you know where you put it and that s all that matters What about point Well it turns out that you ve been setting point every time you move the cursor because point just refers to your current location in the buffer In formal terms point is the spot where text would be inserted if you were to type something By setting the mark and then moving to the end of the block of text you have actually defined a block of text This block is known as the region The region always means the area between mark and point Merely defining the region does not make it available for pasting You have to tell Emacs to copy it in order to be able to paste it To copy the region make sure that mark and point are set correctly and type M w It has now been recorded by Emacs In order to paste it somewhere else just go there and type C y This is known as yanking the text into the buffer If you want to actually move the text of the region to somewhere else type C w instead of M w This will kill the region all the text inside it will disappear In fact it has been saved in the same way as if you had used M w You can yank it back out with C y as always The place Emacs saves all this text is known as the kill ring Some editors call it the clipboard
30. al Public License see the accompanying COPYING file for more details INSTALLING the kernel Emacs README Fundamental Top the cursor automatically moves to the next line C b for backward has the opposite behavior And while we re at it C n and C p take you to the next and previous lines respectively Using the control keys is usually the quickest way of moving around when you re editing The goal of Emacs is to keep your hands over the alpha numeric keys of the keyboard where most of your work gets done However if you want to the arrow keys should also work In fact when you re using X you should be able to position the mouse pointer and click with the left button to move the cursor where you want However this is very slow you have to move your hand all the way to your mouse Most people who use Emacs primarily use the keyboard for getting around Use C p and C b to get all the way back to the upper left corner Now keep C b held a little longer You should hear an annoying bell sound and see the message Beginning of buffer appear in the minibuffer At this point you might wonder But what is a buffer When Emacs works on a file it doesn t actually work on the file itself Instead it copies the contents of the file into a special Emacs work area called a buffer where you can modify it to your heart s content When you are done working you tell Emacs to save the buffer in other words to
31. at keys do what in your particular setup To learn about twm s configuration look at Section fvwm s configuration is covered in Sec tion 2 4 1 When New Windows are Created There are three possible things a window manager will do when a new window is created It is possible to configure a window manager so that an outline of the new window is shown and you are allowed to position it on your screen That is called manual placement If you are presented with the outline of a window simply use the mouse to place it where you wish it to appear and click the left mouse button It is also possible that the window manager will place the new window somewhere on the screen by itself This is known as random placement Finally sometimes an application will ask for a specific spot on the screen or the window manager will be configured to display certain applications on the same place of the screen all the time For instance I specify that I want xclock to always appear in the upper right hand corner of the screen 2 4 2 Focus The window manager controls some important things The first thing you ll be interested in is focus The focus of the server is which window will get what you type into the keyboard Usually in X the focus is determined by the position of the mouse cursor If the mouse cursor is in one xterm s window that xterm will get your keypresses This is different from many other windowing systems such as Microsoft Win
32. ath is in relation to your current directory In the above example when I was in usr I made a relative move to local bin local is a directory under usr and bin is a directory under local cd home was also a relative directory change There are two directories used only for relative pathnames and The directory refers to the current directory and is the parent directory These are shortcut directories They exist in every directory but don t really fit the folder in a folder concept Even the root directory has a parent directory it s its own parent The file chapter 1 would be the file called chapter 1 in the current directory Occasion ally you need to put the for some commands to work although this is rare In most cases chapter 1 and chapter 1 will be identical The directory is most useful in backing up o 6You ll see all the terms in this book present working directory current directory or working directory I prefer current directory although at times the other forms will be used for stylistic purposes 1 3 Storing Information 9 usr local bin cd usr local 1s F archives bin emacs etc ka9q 1ib tcl usr local ls F src cweb linux xmris usr local In this example I changed to the parent directory using cd and I listed the directory usr src from usr local using src Note that if I was i
33. ation Alternatively if you want to try to interpret the window manager s configuration file see Section for twm or Section for fvwm 2You can have more then one copy of xterm running at the same time 3Many PCs have only two button mice If this is the case for you you should be able to emulate a middle button by using the left and right buttons simultaneously 2 4 Window Managers 17 2 4 4 Depth Since windows are allowed to overlap in X there is a concept of depth Even though the windows and the screen are both two dimensional one window can be in front of another partially or completely obscuring the rear window There are several operations that deal with depth e Raising the window or bringing a window to the front This is usually accomplished by clicking on a window s title bar with one of the buttons Depending on how the window manager is configured it could be any one of the buttons It is also possible that more then one button will do the job e Lowering the window or pushing the window to the back This can generally be accomplished by a different click in the title bar It is also possible to configure some window managers so that one click will bring the window foward if there is anything over it while that same click will lower it when it is in the front e Cycling through windows is another operation many window managers allow This brings each window to the front in an orderly cycle 2 4 5 Icon
34. bout it being stopped again is misleading To find out whether it s still alive that is either running or frozen in a suspended state type jobs home larry jobs 1 Terminated yes home larry There you have it the job has been terminated It s possible that the jobs command showed nothing at all which just means that there are no jobs running in the background If you just killed a job and typing jobs shows nothing then you know the kill was successful Usually it will tell you the job was terminated Now start yes running again like this home larry yes gt dev null If you read the section about input and output redirection you know that this is sending the output of yes into the special file dev null dev null is a black hole that eats any output sent to it you can imagine that stream of y s coming out the back of your computer and drilling a hole in the wall if that makes you happy After typing this you will not get your prompt back but you will not see that column of y s either Although output is being sent into dev null the job is still running in the foreground As usual you can suspend it by hitting ctrl z Do that now to get the prompt back home larry yes gt dev null yes is running and we just typed ctrl z 1 Stopped yes gt dev null home larry 3 4 Multitasking 29 Hmm is there any way to get it to actually run in the background while
35. by using the Info documentation reader C h i but you may find it easier to deal with treeware than with the online versions Also their prices are quite reasonable and the money goes to a good cause quality free software At some point you should type C h C c to read the copyright conditions for Emacs It s more interesting than you might think and will help clarify the concept of free software If you think the term free software just means that the program doesn t cost anything please do read that copyright as soon as you have time
36. cat listing home larry The exact output of the command 1s usr bin appeared in the contents of listing All well and good although it didn t solve the original problem However cat does do some interesting things when it s output is redirected What does the command cat listing gt newfile do Normally the gt newfile says take all the output of the command and put it in newfile The output of the command cat listing is the file listing So we ve invented a new and not so efficient method of copying files How about the command cat gt fox cat by itself reads in each line typed at the terminal standard input and prints it right back out standard output until it reads Ctrl d In this case standard output has been redirected into the file fox Now cat is serving as a rudimentary editor home larry cat gt fox The quick brown fox jumps over the lazy dog press Ctrl d We ve now created the file fox that contains the sentence The quick brown fox jumps over the lazy dog One last use of the versitile cat command is to concatenate files together cat will print out every file it was given as a parameter one after another So the command cat listing fox will print out the directory listing of usr bin and then it will print out our silly sentence Thus the command cat listing fox gt listandfox will create a new file containing the contents of both listing and fox 3 3 3 Input Redirection Like
37. cessed by clicking on the root window which is an immovable window behind all the other ones By default it is colored gray but could look like anything To try to see a menu click and hold down a button on the desktop A menu should pop up To make a selection move without releasing the mouse button the cursor over one of the items any then release the mouse button 2 5 X Attributes There are many programs that take advantage of X Some programs like emacs can be run either as a text mode program or as a program that creates its own X window However most X programs can only be run under X 2 5 1 Geometry There are a few things common to all programs running under X In X the concept of geometry is where and how large a window is A window s geometry has four components e The horizontal size usually measured in pixels A pixel is the smallest unit that can be colored Many X setups on Intel PCs have 1024 pixels horizontally and 768 pixels vertically Some applications like xterm and emacs measure their size in terms of number of characters they can fit in the window For instance eighty characters across e The vertical size also usually measured in pixels It s possible for it to be measured in char acters e The horizontal distance from one of the sides of the screen For instance 35 would mean make the left edge of the window thirty five pixels from the left edge of the screen On the other hand 50 would mean
38. ch as your shell bash reads your commands from standard input It is also possible for a program to write to standard error since it is very easy to make standard output point somewhere besides your terminal Standard error stderr is almost always connected to a terminal so an actual human will read the message In this section we re going to examine three ways of fiddling with the standard input and output input redirection output redirection and pipes 2cp etc passwd this is a long file 26 Chapter 3 Working with Unix 3 3 2 Output Redirection A very important feature of Unix is the ability to redirect output This allows you instead of viewing the results of a command to save it in a file or send it directly to a printer For instance to redirect the output of the command 1s usr bin we place a gt sign at the end of the line and say what file we want the output to be put in home larry 1s home larry ls F usr bin gt listing home larry 1s listing home larry As you can see instead of writing the names of all the files the command created a totally new file in your home directory Let s try to take a look at this file using the command cat If you think back you ll remember cat was a fairly useless command that copied what you typed the standard input to the terminal the standard output cat can also print a file to the standard output if you list the file as a parameter to cat home larry
39. cmuscheme Run an inferior Scheme the way I like it t The function autoload takes the name of a function quoted with for reasons having to do with how Lisp works and tells Emacs that this function is defined in a certain file The file is the second argument a string without the el or elc extension indicating the name of the file to search for in the load path The remaining arguments are optional but necessary in this case the third argument is a documentation string for the function so that if you call describe function on it you get some useful information The fourth argument tells Emacs that this autoloadable function can be called interactively that is by using M x This is very important in this case because one should be able to type M x run scheme to start a scheme process running under Emacs Now that run scheme has been defined as an autoloadable function what happens when I type M x run scheme Emacs looks at the function run scheme sees that it s set to be autoloaded and loads the file named by the autoload in this case cmuscheme The byte compiled file cmuscheme elc exists so Emacs will load that That file must define the function run scheme or there will be an autoload error Luckily it does define run scheme so everything goes smoothly and I get my preferred Scheme interface An autoload is a like a promise to Emacs that when the time comes it can find the specified fu
40. code a shell script or something else and to display general files such as configuration files When necessary for clarity s sake these examples or figures will be enclosed in thin boxes 1 The Unix Shell IL Unik Commands sg oa a aa NN Key Represents a key to press You will often see it in this form Press return to 1 1 A Typical Unix Command continue 1 27 Helping Yourself O a AE Y A e Re A AN ee EY o A diamond in the margin like a black diamond on a ski hill marks danger or 1 3 Storing Information ooo caution Read paragraphs marked this way carefully 3 1 Looking at Directories With 1s o ooo e 3 2 The Current Directory and cd sc 668 oras oa a ea 3 3 Creating and Removing Directories o o e e 14 Moving Informations 2 2 0 0 200 A Oe ae etek te ee ee This X in the margin indicates special instructions for users of the X Window Ar sep Bike Monk s e sard da ad Sue ed a POL ale Deon E dao es System eo Pruning Back with tie b i ele got ae on Re eae wed 4 3 A Forklift Can Be Very Handy i eye eh a a 2 The X Window System 2 1 Starting and Stopping the X Window System o o e This indicates a paragraph that contains special information that should be read ZIMIO id at es A A A a da eas carefully DO e nto Mee hays lt 8 ved fe i hi 8 Marina dee lakawec Berean le 2 2 What is The X Window System 665 i
41. d gadfly and type C s That puts you in isearch mode Now start typing the word you are searching for gadfly But as soon as you type the g you see that Emacs has jumped you to the first occurence of g in the buffer If the above quote is the entire contents of the buffer then that would be the first g of the word growing Now type the a of gadfly and Emacs leaps over to gasoline which contains the first occurence of a ga The d gets you to gadzooks and finally f gets you to gadfly without your having had to type the entire word What you are doing in an isearch is defining a string to search for Each time you add a character to the end of the string the number of matches is reduced until eventually you have entered enough to define the string uniquely Once you have found the match you are looking for you can exi the search with Return or any of the normal movement commands If you think the string you re looking for is behind you in the buffer then you should use C r which does an isearch backwards If you encounter a match but it s not the one you were looking for then hit C s again while still in the search This will move you forward to the next complete match each time you hit it I there is no next match it will say that the search failed but if you press C s again at that point the search will wrap around from the beginning of the buffer The rev
42. d Scheme are just some Generally it knows how to indent them in intuitive ways 4 11 3 Mail Mode You can also edit and send mail in Emacs To enter a mail buffer type C x m You need to fill in the To and Subject fields and then use C n to get down below the separator line into the body of the message which is empty when you first start out Don t change or delete the separator line or else Emacs will not be able to send your mail it uses that line to distinguish the mail s headers which tell it where to send the mail from the actual contents of the message You can type whatever you want below the separator line When you are ready to send the message just type C c C c and Emacs will send it and then make the mail buffer go away 4 12 Being Even More Efficient Experienced Emacs users are fanatical about efficiency In fact they will often end up wasting a lot of time searching for ways to be more efficient While I don t want that to happen to you there are some easy things you can do to become a better Emacs user Sometimes experienced users make novices feel silly for not knowing all these tricks for some reason people become religious about using Emacs correctly Pd condemn that sort of elitism more if I weren t about to be guilty of it myself Here we go When you re moving around use the fastest means available You know that C f is forward char can you guess that M f is forward word C b is backward char G
43. dows OS 2 or the Macintosh where you must click the mouse in a window before that window gets focus Usually under X if your mouse cursor wanders from a window focus will be lost and you ll no longer be able to type there Note however that it is possible to configure both twm and fvwm so that you must click on or in a window to gain focus and click somewhere else to lose it identical to the behavior of Microsoft Windows Either discover how your window manager is configured by trial and error or consult local documentation 2 4 3 Moving Windows Another very configurable thing in X is how to move windows around In my personal configuration of twm there are three different ways of moving windows around The most obvious method is to move the mouse cursor onto the title bar and drag the window around the screen Unfortunately this may be done with any of the left right or middle buttons To drag move the cursor above the title bar and hold down on the button while moving the mouse Most likely your configuration is set to move windows using the left mouse buttons Another way of moving windows may be holding down a key while dragging the mouse For instance in my configuration if I hold down the Alt key move the cursor above a window I can drag the window around using the left mouse button Again you may be able to understand how the window manager is configured by trial and error or by seeing local document
44. eader Info is too complex a subject to go into here but if you are interested in exploring it on your own type C h i and read the paragraph at the top of the screen It will tell you how get more help 4 10 Specializing Buffers Modes Emacs buffers have modes associated with them The reason for this is that your needs when writing a mail message are very different from your needs when say writing a program Rather than try to come up with an editor that would meet every single need all the time which would be impossible the designer of Emacs chose to have Emacs behave differently depending on what you are doing in each individual buffer Thus buffers have modes each one designed for some specific activity The main features that distinguish one mode from another are the keybindings but there can be other differences as well The most basic mode is fundamental mode which doesn t really have any special commands at all In fact here s what Emacs has to say about Fundamental Mode Fundamental Mode Major mode not specialized for anything in particular Other major modes are defined by comparison with this one I got that information like this I typed C x b which is switch to buffer and entered foo when it prompted me for a buffer name to switch to Since there was previously no buffer named foo Emacs created one and switched me to it It was in fundamental mode by default but it it hadn t been I
45. ed The above example comes from my 386 PC running Linux As the above indicates load path is a list of strings Each string names a directory that might contain Emacs Lisp files When Emacs needs to load a file of Lisp code it goes looking for it in each of these directories in order If a directory is named but does not actually exist on the filesystem Emacs just ignores it When Emacs starts up it automatically tries to load the file emacs in your home directory Therefore if you want to make personal customizations to Emacs you should put them in emacs The most common customizations are keybindings so here s how to do them global set key C cl goto line global set key is a function of two arguments the key to be bound and the function to bind it to The word global means that this keybinding will be in effect in all major modes there is another function local set key that binds a key in a single buffer Above I have bound C c 1 to the function goto line The key is described using a string The special syntax C lt char gt Sometimes unofficially called Elisp 44 Chapter 4 Editing files with Emacs means the Control key held down while the key lt char gt is pressed Likewise M lt char gt indicates the Meta key All very well but how did I know that the function s name was goto line I may know that I want to bind C c 1 to some function that prompts for a line n
46. entry should be Exit Window Manager or Exit X or some entry con taining the word Exit Try to find that entry there could be more than one menu try different mouse buttons and choose it The other method would be for a special xterm to control X If this is the case there is probably a window labeled login or system xterm To exit from X move the mouse cursor into that window and type exit If X was automatically started when you logged in one of these methods should log you out Simply login again to return If you started X manually these methods should return you to the text mode prompt If you wish to logout type logout at this prompt 13 14 Chapter 2 The X Window System 2 2 What is The X Window System The X Window System is a distributed graphical method of working developed primarily at the Massachusetts Institute of Technology It has since been passed to a consortium of vendors aptly named The X Consortium and is being maintained by them The X Window System hereafter abbreviated as X 1 has new versions every few years called releases As of this writing the latest revision is X11R6 or release six The eleven in X11 is officially he version number but there hasn t been a new version in many years and one is not currently planned There are two terms when dealing with X that you should be familiar The client is a X program For instance xterm is the client that d
47. er Combinations that use the Control key with a letter are generally bound to unctions that do other things like moving you around For example C v is bound to a function called scroll up which scrolls the buffer up by one screenful meaning that your position in the buffer moves down of course If you ever actually wanted to insert a Control character into the buffer then how would you do it After all the Control characters are ASCII characters although rarely used and you might want hem in a file There is a way to prevent Control characters from being interpreted as commands by Emacs The key C q is bound to a special function named quoted insert All quoted insert does is read the next key and insert it literally into the buffer without trying to interpret it as a command This is how you can put Control characters into your files using Emacs Naturally the way to insert a C q is to press C q twice Emacs also has many functions that are not bound to any key For example if you re typing a long message you don t want to have to hit return at the end of every line You can have Emacs do it for you you can have Emacs do anything for you the command to do so is called auto fill mode but it s not bound to any keys by default In order to invoke this command you would type M x auto fill mode M x is the key used to call functions by name You could even use it to call functions like next line and previous line but that
48. erse holds true for C r it wraps around the end of the buffer Try bringing up a buffer of plain English text and doing and isearch for the string the Firs you d type in as much as you wanted then use repeated C s s to go to all instances of it Notice that it will match words like them as well since that also contains the substring the To search O E nly for the you d have to do add a space to the end of your search string You can add new haracters to the string at any point in the search even after you ve hit C s repeatedly to find the w next matches You can also use Backspace or Delete to remove characters from the search string at any point in the search and hitting Return exits the search leaving you at the last match Emacs also allows you to replace all instances of a string with some new string this is known as query replace To invoke it type query replace and hit Return Completion is done on the command name so once you have typed query re you can just hit Tab to finish it Say you wish to replace all instances of gadfly with housefly At the Query replace prompt type gadfly and hit Return Then you will be prompted again and you should enter housefly Emacs will then step through the buffer stopping at every instance of the word
49. expected to type everything in each time you are going to use the program Of course not Unix provides files and directories A directory is like a folder it contains pieces of paper or files A large folder can even hold other folders directories can be inside directories In Unix the collection of directories and files is called the file system Initially the file system consists of one directory called the root directory Inside this directory there are more directories and inside those directories are files and yet more directories Each file and each directory has a name It has both a short name which can be the same as another file or directory somewhere else on the system and a long name which is unique A short name for a file could be joe while it s full name would be home larry joe The full name is usually called the path The path can be decode into a sequence of directories For example here is how home larry joe is read 4 man will also display information on a system call a subroutine a file format and more In the original version of Unix it showed the exact same information the printed documentation would For now you re probably only interested in getting help on commands 5There may or may not be a limit to how deep the file system can go I ve never reached it one can easily have directories 10 levels deep 6 Chapter 1 The Unix Shell Figure 1 1 A typical abridged Unix di
50. f file It is a control character that tells Unix programs that you or another program is done entering data When cat sees you aren t typing anything else it terminates For a similar idea try the program sort As its name indicates it is a sorting program If you type a couple of lines then press Ctrl d it will output those lines in a sorted order These types of programs are called filters because they take in text filter it and output the text slightly differently Both cat and sort are unusual filters cat is unusual because it reads in text and performs no changes on it sort is unusual because it reads in lines and doesn t output anything until after it s seen the EOF character Many filters run on a line by line basis they will read in a line perform some computations and output a different line 2The u indicates that the user typed a space 3Hold down the key labeled Ctrl and press d then let go of both al 1 2 Helping Yourself 1 2 Helping Yourself The man command displays reference pages for the command you specify For example home larry man cat cat 1 cat 1 NAME cat Concatenates or displays files SYNOPSIS cat benstuvAET number number nonblank squeeze blank show nonprintingl show ends show tabs show a11 help version file DESCRIPTION This manual page documents the GNU version of cat
51. filling or auto wrapping has gotten screwed up use M q which is fill paragraph in common text modes This will adjust the paragraph you re in as if it had been wrapped line by line but without your having to go mess around with it by hand M q will work from inside the paragraph or from its very beginning or end 4 13 Customizing Emacs 43 Sometimes it s helpful to use C x u undo which will try to undo the last change s you made Emacs will guess at how much to undo usually it guesses very intelligently Calling it repeatedly will undo more and more until Emacs can no longer remember what changes were made 4 13 Customizing Emacs Emacs is so big and so complex that it actually has its own programming language I m not kidding to really customize Emacs to suit your needs you have to write programs in this language It s called Emacs Lisp and it s a dialect of Lisp so if you have previous experience in Lisp it will seem quite friendly If not don t worry I m not going to go into a great deal of depth because it s definitely best learned by doing To really learn about programming Emacs you should consult the Info pages on Emacs Lisp and read a lot of Emacs Lisp source code Most of Emacs s functionality is defined in files of Emacs Lisp code Most of these files are distributed with Emacs and collectively are known as the Emacs Lisp library This li brary s location depends on how Emacs
52. g 35 make C programs indent the way I like them to setq c indent level 2 The first expression causes searches including isearch to be case insensitive that is the search will match upper or lower case versions of a character even though the search string contains only the lower case version The second expression sets the default indentation for C language statements to be a little smaller than it is normally this is just a personal preference I find that it makes C code more readable The comment character in Lisp is inside a literal string like so Emacs ignores anything following one unless it appears 4 13 Customizing Emacs 45 35 these two lines are ignored by the Lisp interpreter but the 33 s expression following them will be evaluated in full setq some literal string An awkward pause for no purpose It s a good idea to comment your changes to Lisp files because six months later you will have no memory of what you were thinking when you modified them If the comment appears on a line by itself precede it with two semicolons This aids Emacs in indenting Lisp files correctly You can find out about internal Emacs variables the same ways you find out about functions Use C h v describe variable to make a completion list or use C h C a apropos Apropos differs from C h a command apropos in that it shows functions and variables instead of just functions The default extension for Emacs Lisp files is
53. g yes gt dev null amp 3 Stopped yes uniq gt dev null home larry The means that job number 1 is second in line to be put in the foreground if you just type fg without giving it any parameters The means the specified job is first in line a fg without parameters will bring job number 3 to the foreground However you can get to it by naming it if you wish home larry fg 1 yes gt dev null now type ctrl z to suspend it 1 Stopped yes gt dev null home larry Having changed to job number 1 and then suspending it has also changed the priorities of all your jobs You can see this with the jobs command home larry jobs 1 Stopped yes gt dev null 3 Stopped yes uniq gt dev null home larry Now they are both stopped because both were suspended with ctrl z and number 1 is next in line to come to the foreground by default This is because you put it in the foreground manually and then suspended it The always refers to the most recent job that was suspended from the foreground You can start it running again home larry bg 1 yes gt dev null amp home larry jobs 1 Running yes gt dev null 3 Stopped yes uniq gt dev null home larry Notice that now it is running and the other job has moved back up in line and has the Now let s kill them all so your system isn t permanently slowed by processes doing nothing home larry kill
54. gadfly and asking if you want to replace it Just hit y or n at each instance for Yes or No until it finishes If this doesn t make sense as you read it then try it out 4 8 What s Really Going On Here Actually all these keybindings you have been learning are shortcuts to Emacs functions For exam ple C p is a short way of telling Emacs to execute the internal function previous line However 4 9 Asking Emacs for Help 39 all these internal functions can be called by name using M x If you forgot that previous line is bound to C p you could just type M x previous line Return and it would move you up one line Try this now to understand how M x previous line and C p are really the same thing The designer of Emacs started from the ground up first defining a whole lot of internal functions and then giving keybindings to the most commonly used ones Sometimes it s easier just to call a function explicitly with M x than to remember what key it s bound to The function query replace for example is bound to M in some versions of Emacs But who can remember such an odd keybinding Unless you use query replace extremely often it s easier just to call it with M x Most of the keys you type are letters meant to be inserted into the text of the buffer So each of those keys is bound to the function self insert command which does nothing but insert that letter into the buff
55. h than just searching a completion list in my opinion but you may find that you feel differently Try both methods and see what you think There is always the possibility that Emacs does not have any predefined function to do what you re looking for In this situation you have to write the function yourself I m not going to talk about how to do that you should look at the Emacs Lisp library for examples of function definitions and read the Info pages on Emacs Lisp If you happen to know a local Emacs guru ask her how to do it Defining your own Emacs functions is not a big deal to give you an idea I have written 131 of them in the last year or so It takes a little practice but the learning curve is not steep at all Another thing people often do in their emacs is set certain variables to preferred values For example put this in your emacs and then start up a new Emacs setq inhibit startup message t Emacs checks the value of the variable inhibit startup message to decide whether or not to display certain information about version and lack of warranty when it starts up The Lisp expression above uses the command setq to set that variable to the value t which is a special Lisp value that means true The opposite of t is nil which is the designated false value in Emacs Lisp Here are two things that are in my emacs that you might find useful setq case fold search nil gives case insensitivity in searchin
56. ified airly often If a person s emacs contains any errors Emacs will not attempt to load default el but instead will just stop flashing a message saying Error in init file or something If you see his message there s probably something wrong with your emacs There is one more kind of expression that often goes in a emacs The Emacs Lisp library sometimes offers multiple packages for doing the same thing in different ways This means that you have to specify which one you want to use or you ll get the default package which is not always the best one for all purposes One area in which this happens is Emacs s Scheme interaction features There are two different Scheme interfaces distributed with Emacs in version 19 at least xscheme and cmuscheme prompt gt ls usr lib emacs 19 19 lisp scheme usr 1ib emacs 19 19 lisp cmuscheme el usr lib emacs 19 19 1isp cmuscheme elc usr lib emacs 19 19 1isp scheme el usr 1ib emacs 19 19 lisp scheme elc usr lib emacs 19 19 1isp xscheme el usr lib emacs 19 19 1isp xscheme elc I happen to like the interface offered by cmuscheme much better than that offered by xscheme but the one Emacs will use by default is xscheme How can I cause Emacs to act in accordance with my preference I put this in my emacs 353 notice how the expression can be broken across two lines Lisp 35 ignores whitespace generally 46 Chapter 4 Editing files with Emacs autoload run scheme
57. ing about standards is that there are so many of them to choose from Andrew S Tanenbaum This chapter only applies to those using the X Window System If you encounter a screen with multiply windows colors or a cursor that is only movable with your mouse you are using X If your screen consists of white characters on a black background you are not currently using X If you want to start it up take a look at Section 2 1 2 1 Starting and Stopping the X Window System 2 1 1 Starting X Even if X doesn t start automatically when you login it is possible to start it from the regular text mode shell prompt There are two possible commands that will start X either startx or xinit Try startx first If the shell complains that no such command is found try using xinit and see if X starts If neither command works you may not have X installed on your system consult local documentation for your distribution Tf the command runs but you are eventually returned to the black screen with the shell prompt X is installed but not configured Consult the documentation that came with your distribution on how to setup X 2 1 2 Exiting X Depending on how X is configured there are two possible ways you might have to exit X The first is if your window manager controls whether or not X is running If it does yow ll have to exit X using a menu see Section 2 4 8 on page 18 To display a menu click a button on the background The important menu
58. is the trailing amp at the end of the first two Putting an amp after a command tells the shell to start in running in the background right from the very beginning It s just a way to avoid having to start the program type ctrl z and then type bg So we started those two commands running in the background The third is suspended and inactive at the moment You may notice that the machine has become slower now as the two running ones require some amount of CPU time Each one told you it s job number The first two also showed you their process identification numbers or PID s immediately following the job number The PID s are normally not something you need to know but occasionally come in handy Let s kill the second one since I think it s making your machine slow You could just type kill 2 but that would be too easy Instead do this home larry fg 2 yes sort gt dev null type ctrl c to kill it home larry As this demonstrates fg takes parameters beginning with as well In fact you could just have typed this 30 Chapter 3 Working with Unix home larry 2 yes sort gt dev null type ctrl c to kill it home larry This works because the shell automatically interprets a job number as a request to put that job in the foreground It can tell job numbers from other numbers by the preceding Now type jobs to see which jobs are left running home larry jobs 1 Runnin
59. isplayed text If the text displayed is all there is the entire scroll bar is dark If the middle half of the text is displayed the middle half of the scroll bar is darkened A vertical scroll bar may be to the left or right of the text and a horizontal one may be above or below depending the application 2 6 Common Features 21 2 6 3 1 Athena scroll bars Athena scroll bars operate differently from scroll bars in other windowing systems Each of the three buttons of the mouse operate differently To scroll upwards that is display material above what is currently visible you can click the rightmost mouse button anywhere in the scroll bar To scroll downwards click the left mouse button anywhere in the scroll bar You can also jump to a particular location in the displayed material by clicking the middle mouse button anywhere in the scroll bar This causes the window to display material starting at that point in the document 2 6 3 2 Motif scroll bars A Motif scroll bar acts much more like a Microsoft Windows or Macintosh scroll bar An example of one is on the right in Figure 2 4 Notice that in addition to the bar it has arrows above and below it These are used for fine tuning clicking either the left or middle buttons on them will scroll a small amount such as one line the right button does nothing The behavior of clicking inside the scroll bar is widely different for Motif scroll bars than Athena scroll bars The right button
60. isplays your shell when you log on The server is a program hat provides services to the client program For instance the server draws the window for xterm and communicates with the user Since the client and the server are two separate programs it is possible to run the client and the server on two physically separate machines In addition to supplying a standard method of doing graphics you can run a program on a remote machine across the country if you like and have it display on the workstation right in front of you A third term you should be familiar with is the window manager The window manager is a special client that tells the server where to position various windows and provides a way for the user to move these windows around The server by itself does nothing for the user It is merely there to provide a buffer between the user and the client 2 3 What s This on my Screen When you first start X several programs are started First the server is started Then several clients are usually started Unfortunately this is not standardized across various distributions It is likely that among these clients are a window manager either fvwm or twm a prompt xterm and a clock xclock 2 3 1 XClock xclock digital analog update seconds hands color Tl explain the simpliest one first xclock functions exactly as you d expect it would It ticks off the seconds minutes and hours in a small window No amounts
61. it s becoming more and more common so Ill cover it too Much of what is true for Scheme mode is true for Lisp mode as well if you prefer to write in Lisp Well to make matters painful Emacs comes with two different Scheme modes because people couldn t decide how they wanted it to work The one I m describing is called cmuscheme and later on in the section on customizing Emacs I ll talk about how there can be two different Scheme modes and what to do about it For now don t worry about it if things in your Emacs don t quite match up to what I say here A customizable editor means an unpredictable editor and there s no way around that You can run an interactive Scheme process in Emacs with the command M x run scheme This creates a buffer named scheme which has the usual Scheme prompt in it You can type in Scheme expressions at the prompt hit Return and Scheme will evaluate them and display the answer Thus in order to interact with the Scheme process you could just type all your function definitions and applications in at the prompt Chances are you have previously written Scheme source code in a file somewhere and it would be easier to do your work in that file and send the definitions over to the Scheme process buffer as necessary Tf that source file ends in ss or scm it will automatically be brought up in Scheme mode when you find it with C x C f If for some reason it doesn t come u
62. ization There are several other operations that can obscure windows or hide them completely First is the idea of iconization Depending on the window manager this can be done in many different ways In twm many people configure an icon manager This is a special window that contains a list of all the other windows on the screen If you click on a name depending on the setup it could be with any of the buttons the window disappears it is iconified The window is still active but you can t see it Another click in the icon manager restores the window to the screen This is quite useful For instance you could have remote xterms to many different computers that you occasionally use However since you rarely use all of them at a given time you can keep most of the xterm windows iconified while you work with a small subset The only problem with this is it becomes easy to lose windows This causes you to create new windows that duplicate the functionality of iconified windows Other window managers might create actual icons across the bottom of the screen or might just leave icons on the root window 2 4 6 Resizing There are several different methods to resize windows under X Again it is dependent on your window manager and exactly how your window manager is configured The method many Microsoft Windows users are familiar with is to click on and drag the border of a window If your window manager creates large borders that
63. l if you were to guess that there is a command called insert file you d be right To check your educated guess type C h f At the prompt in the minibuffer enter the name of a function that you want help on Since you know that there is completion on function names and you can guess that the command you are looking for begins with insert you type insert and hit Tab This shows you all the function names that begin with insert and insert file is one of them So you complete the function name and read about how it works and then use M x insert file If you re wondering whether it s also bound to a key you type C h w insert file Return and find out The more you know about Emacs s help facilities the more easily you can ask Emacs questions about itself The ability to do so combined with a spirit of exploration and a willingness to learn new ways of doing things can end up saving you a lot of keystrokes 10By the way cmuscheme was the interface I was talking about earlier in the section on working with Scheme so if you want to use any of the stuff from that tutorial you need to make sure that you run cmuscheme 4 14 Finding Out More 47 To order a copy of the Emacs user s manual and or the Emacs Lisp Programming manual write to Free Software Foundation 675 Mass Ave Cambridge MA 02139 USA Both of these manuals are distributed electronically with Emacs in a form readable
64. like this M x then you ve found it To get rid o he prompt and go back to your Emacs buffer type C g If you didn t get a prompt then there is still one solution You can use the Escape key as a Meta key But instead of holding it down while you type the next letter you have to tap it and release it quickly and then type the letter This method will work whether or not you have a rea Meta key so it s the safest way to go Try tapping Escape and then typing x now You should get that tiny prompt again Just use C g to make it go away C g is the general way in Emacs to quit out of something you don t mean to be in It usually beeps annoyingly at you to let you know hat you have interrupted something but that s fine since that s what you intended to do if you yped C g 4 The notation M x is analogous to C x substitute any character for x If you have found a real Meta key use that otherwise just use the Escape key I will simply write M x and you ll have o use your own Meta key 4 6 Cutting Pasting Killing and Yanking Emacs like any good editor allows you to cut and paste blocks of text In order to do this you need a way to define the start and end of the block In Emacs you do this by setting two locations in the buffer known as mark and point To set the mark go to the place you want your block to begin and type C SPC SPC means Sp
65. ls type C h C p Ignore it for now we won t be making much use of the minibuffer for a while Before you actually change any of the text in the file you need to learn how to move around The cursor should be at the beginning of the file in the upper left corner of the screen To move forward type C f that is hold down the Control key while you press f for forward It will move you forward a character at a time and if you hold both keys down your system s automatic key repeat should take effect in a half second or so Notice how when you get to the end of the line lFor instance cp usr src linux README README 33 34 Chapter 4 Editing files with Emacs Figure 4 1 Emacs was just started with emacs README Linux kernel release 1 0 These are the release notes for linux version 1 0 Read them carefully as they tell you what this is all about explain how to install the kernel and what to do if something goes wrong WHAT IS LINUX Linux is a Unix clone for 386 486 based PCs written from scratch by Linus Torvalds with assistance from a loosely knit team of hackers across the Net It aims towards POSIX compliance It has all the features you would expect in a modern fully fledged Unix including true multitasking virtual memory shared libraries demand loading shared copy on write executables proper memory management and TCP IP networking It is distributed under the GNU Gener
66. matically brought up in c mode This means that certain special editing commands useful for writing C programs are available In C mode Tab is bound to c indent command This means that hitting the Tab key does not actually insert a tab character Instead if you hit Tab anywhere on a line Emacs automatically indents that line correctly for its location in the program This implies that Emacs knows something about C syntax which it does although nothing about semantics it cannot insure hat your program has no errors In order to do this it assumes that the previous lines are indented correctly That means that if he preceding line is missing a parenthesis semicolon curly brace or whatever Emacs will indent he current line in a funny way When you see it do that you will know to look for a punctuation mistake on the line above You can use this feature to check that you have punctuated your programs correctly instead of reading through the entire program looking for problems just start indenting lines from the top down with Tab and when something indents oddly check the lines just before it In other words let Emacs do the work for you 4 11 2 Scheme Mode This is a major mode that won t do you any good unless you have a compiler or an interpreter for the Scheme programming language on your system Having one is not as normal as having say a C compiler but
67. n home larry typing 1s F src wouldn t do me any good The directory is an alias for your home directory usr local ls F usr local You can see at a glance that there isn t anything in your home directory will become more useful as we learn more about how to manipulate files 1 3 3 Creating and Removing Directories mkdir directory1 directory2 directoryNl Creating your own directories is extremely simple under Unix and can be a useful organizational tool To create a new directory use the command mkdir Of course mkdir stands for make directory Let s do a small example to see how this works home larry ls F home larry mkdir report 1993 home larry ls F report 1993 home larry cd report 1993 home larry report 1993 mkdir can take more than one parameter interpreting each parameter as another directory to create You can specify either the full pathname or a relative pathname report 1993 in the above example is a relative pathname home larry report 1993 mkdir home larry report 1993 chap1 report 1993 chap2 home larry report 1993 ls F chap1 chap2 home larry report 1993 rmdir directory1 directory2 directoryN The opposite of mkdir is rmdir remove directory rmdir works exactly like mkdir An example of rmdir is home larry report 1993 rmdir chapi chap3 rmdir chap3 No such file or directory home larry report 1993 ls F chap2 home larry re
68. n them and provided that the en resulting derived work is distributed under the terms of a permission notice identical to this on Permission is granted to copy and distribute translations of this manual into another language un the conditions for modified versions The GNU General Public License and The GNU Libr General Public License may be included in a translation approved by the Free Software Foundat instead of in the original English At your option you may distribute verbatim and modified versions of this document under terms of the GNU General Public License excepting the clearly marked sections held under sepe copyright Exceptions to these rules may be granted for various purposes Write to Larry Greenfielc the above address or email leg andrew cmu edu and ask It is requested but not required t you notify the author whenever commercially or large scale printing this document Royalties donations are accepted and will encourage further editions These are some of the typographical conventions used in this book Bold Used to mark new concepts WARNINGS and keywords in a language italics Used for emphasis in text slanted Used to mark meta variables in the text especially in representations of the command line For example 1s 1 foo where foo would stand for a filename Content S such as bin cp Typewriter Used to represent screen interaction Also used for code examples whether it is C
69. nction in the file you tell it to look in In return you get some control over what gets loaded Also autoloads help cut down on Emacs s size in memory by not loading certain features until they are asked for Many commands are not really defined as functions when Emacs starts up Rather they are simply set to autoload from a certain file If you never invoke the command it never gets loaded This space saving is actually vital to the functioning of Emacs if it loaded every available file in the Lisp library Emacs would take twenty minutes just to start up and once it was done it might occupy most of the available memory on your machine Don t worry you don t have to set all these autoloads in your emacs they were taken care of when Emacs was built 4 14 Finding Out More I have not told you everything there is to know about Emacs In fact I don t think I have even told you 1 of what there is to know about Emacs While you know enough to get by there are still lots of time saving tricks and conveniences that you ought to find out about The best way to do this is to wait until you find yourself needing something and then look for a function that does it The importance of being comfortable with Emacs s online help facilities cannot be emphasized enough For example suppose you want to be able to insert the contents of some file into a buffer that is already working on a different file so that the buffer contains both of them Wel
70. o be learned here First you should learn what 1s does Try a few other directories that are shown in Figure 1 1 and see what they contain Naturally some will be empty and some will have many many files in them I suggest you try 1s both with and without the F option For example 1s usr local looks like home larry ls usr local archives bin emacs etc ka9q lib tcl home larry The second lesson is more general Many Unix commands are like 1s They have options which are generally one character after a dash and they have parameters Unlike 1s some commands require certain parameters and or options To show what commands generally look like we ll use the following form 1s aRF directory Tll generally use command templates like that before I introduce any command from now on The first word is the command in this case 1s Following the command are all the parameters Optional parameters are contained in brackets P and Meta variables are slanted they re words that take the place of actual parameters For example above you see directory which should be replaced by the name of a real directory Options are a special case They re enclosed by brackets but you can take any one of them without using all of them For instance with just the three options given for 1s you have eight different ways of running the command with or without each of the options Contrast 1s R with ls F 8 Chapter 1
71. oading and saving files many of them will be described ater The Edit menu displays some commands for editing one buffer and the Help menu should hopefully give on line documentation You ll notice keyboard equivalents are listed next to the choices in the menu Since in the long run they ll be quicker you might want to learn them Also for better or for worse most of Emacs s unctionality is only available through the keyboard you might want to read the rest of this chapter 4 3 Editing Many Files at Once Emacs can work on more than one file at a time In fact the only limit on how many buffers your Emacs can contain is the actual amount of memory available on the machine The command to bring a new file into an Emacs buffer is C x C f When you type it you will be prompted for a filename in the minibuffer Find file The syntax here is the same one used to specify files from the shell prompt slashes represent subdirectories means your home directory You also get filename completion meaning that if 36 Chapter 4 Editing files with Emacs you ve typed enough of a filename at the prompt to identify the file uniquely you can just hit Tab to complete it or to show possible completions if there are more than one Space also has a role in filename completion in the minibuffer similar to Tab but Pll let you experiment to find out how the two differ Once y
72. on t work input redirection only works with files not commands You could do this home larry 1s usr bin gt temp 1s home larry more temp 1s home larry rm temp 1s However Unix supplies a much cleaner way of doing that You can just use the command 1s usr bin more The character indicates a pipe Like a water pipe a Unix pipe controls flow Instead of water we re controlling the flow of information A useful tool with pipes are programs called filters A filter is a program that reads the standard input changes it in some way and outputs to standard output more is a filter it reads the data that it gets from standard input and displays it to standard output one screen at a time letting you read the file more isn t a great filter because its output isn t suitable for sending to another program Other filters include the programs cat sort head and tail For instance if you wanted to read only the first ten lines of the output from 1s you could use 1s usr bin head 3 4 Multitasking 3 4 1 Using Job Control Job control refers to the ability to put processes another word for programs essentially in the background and bring them to the foreground again That is to say you want to be able to make something run while you go and do other things but have it be there again when you want to tell it something or stop it In Unix the main tool for job control is the shell it will keep track of jobs for you if y
73. ou have the full filename in the minibuffer hit Return and Emacs will bring up a buffer displaying that file In Emacs this process is known as finding a file Go ahead and find some other unimportant text file now and bring it into Emacs do this from our origina buffer some_file txt Now you have a new buffer I ll pretend it s called another_file txt since I can t see your mode line Your original buffer seems to have disappeared youw re probably wondering where it went It s still inside Emacs and you can switch back to it with C x b When you type this you will see tha the minibuffer prompts you for a buffer to switch to and it names a default The default is the buffer you d get if you just hit Return at the prompt without typing a buffer name The defaul buffer to switch to is always the one most recently left so that when you are doing a lot of work between two buffers C x b always defaults to the other buffer which saves you from having to type the buffer name Even if the default buffer is the one you want however you should try typing in its name anyway Notice that you get the same sort of completion you got when finding a file hitting Tab completes as much of a buffer name as it can and so on Whenever you are being prompted for something in the minibuffer it s a good idea to see if Emacs is doing completion Taking advantage of completion whenever it s offe
74. ou learn how to speak its language The two most important words in that language are fg for foreground and bg for background To find out how they work use the command yes at a prompt home larry yes This will have the startling effect of running a long column of y s down the left hand side of your screen faster than you can follow To get them to stop you d normally type ctrl c to kill it but instead you should type ctrl z this time It appears to have stopped but there will be a message before your prompt looking more or less like this 1 Stopped yes 4more is named because that s the prompt it originally displayed more In many versions of LINUX the more command is identical to a more advanced command that does all that more can do and more Proving that computer programmers make bad comedians they named this new program less 5There are good reasons for this strange command to exist Occasional commands ask for confirmation a answer to a question The yes command allows a programmer to automate the response to these questions yes 28 Chapter 3 Working with Unix It means that the process yes has been suspended in the background You can get it running again by typing fg at the prompt which will put it into the foreground again If you wish you can do other things first while it s suspended Try a few 1s s or something before you put it back in the foreground
75. p in Scheme mode you can do it by hand with M x scheme mode This scheme mode is not the same thing as the buffer running he Scheme process rather the source code buffer s being in scheme mode means that it has special commands for communicating with the process buffer If you put yourself inside a function definition in the Scheme source code buffer and type C c C e then that definition will be sent to the process buffer exactly as if you had typed it in yourself C c M e sends the definition and then brings you to the process buffer to do some interactive work C c C 1 loads a file of Scheme code this one works from either the process buffer or the source code buffer And like other programming language modes hitting Tab anywhere on a line of code correctly indents that line 42 Chapter 4 Editing files with Emacs If you re at the prompt in the process buffer you can use M p and M n to move through your previous commands also known as the input history So if you are debugging the function rotate and have already applied it to arguments in the process buffer like so gt rotate a b c d e then you can get that command back by typing M p at the prompt later on There should be no need to retype long expressions at the Scheme prompt get in the habit of using the input history and you ll save a lot of time Emacs knows about quite a few programming languages C C Lisp an
76. port 1993 cd home larry rmdir report 1993 rmdir report 1993 Directory not empty home larry 10 Chapter 1 The Unix Shell As you can see rmdir will refuse to remove a non existant directory as well as a directory that has anything in it Remember report 1993 has a subdirectory chap2 in it There is one more interesting thing to think about rmdir what happens if you try to remove your current directory Let s find out home larry cd report 1993 home larry report 1993 ls F chap2 home larry report 1993 rmdir chap2 home larry report 1993 rmdir rmdir Operation not permitted home larry report 1993 Another situation you might want to consider is what happens if you try to remove the parent of your current directory This turns out not to be a problem since the parent of your current directory isn t empty so it can t be removed 1 4 Moving Information All of these fancy directories are very nice but they really don t help unless you have some place to store you data The Unix Gods saw this problem and they fixed it by giving the users files We will learn more about creating and editing files in the next few chapters The primary commands for manipulating files under Unix are cp mv and rm They stand for copy move and remove respectively 1 4 1 cp Like a Monk cp i source destination cp i filel file2 fileN destination directory cp is a very useful utility under Uni
77. r them in the obvious ways If you think that you might be returning to Emacs later don t use C x C c at all use C z which will suspend Emacs You can return to it with the shell command fg later This is more efficient than stopping and starting Emacs multiple times especially if you have edit the same files again later Under X hitting C z will merely iconize the window See the section on iconization in Chapter 2 This gives you two ways of iconizing Emacs the normal way your window manager offers and C z Remember when you iconize a simply fg won t bring the window back you ll have to use your window manager 3If you are not the root user on the machine you shouldn t be able to hurt the system anyway but be careful just the same 4 5 The Meta Key 37 4 5 The Meta Key You ve already learned about one modifier key in Emacs the Control key There is a second one called the Meta key which is used almost as frequently However not all keyboards have their Meta key in the same place and some don t have one at all The first thing you need to do is find where your Meta key is located Chances are your keyboard s Alt keys are also Meta keys if you are using an IBM PC or other another keyboard that has an Alt key The way to test this is to hold down a key that you think might be a Meta key and type x I you see a little prompt appear in the minibuffer
78. re aren t any files Thus the lack of output was 1s s way of saying it didn t find any files But I just said there could be 8000 or more files lying around where are they You ve run into the concept of a current directory You can see in your prompt that your current directory is home larry where you don t have any files If you want a list of files of a more active directory try the root directory home larry 1s bin etc install mnt root user var dev home lib proc tmp usr vmlinux home larry In the above command 1s the directory is a parameter The first word of the command is the command name and anything after it is a parameter Parameters generally modify what the program is acting on for 1s the parameters say what directory you want a list for Some commands have special parameters called options or switches To see this try home larry 1s F bin etc install mnt root user var dev home lib proc tmp usr vmlinux home larry The F is an option An option is a special kind of parameter that starts with a dash and modifies how the program runs but not what the program runs on For 1s F is an option that lets you see which ones are directories which ones are special files which are programs and which are normal files Anything with a slash is a directory We ll talk more about 1s s features later It s a surprisingly complex program Now there are two lessons t
79. rectory tree bin m dev pete home larry L sam lib _ proc tmp usr X11R6 H bin emacs etc g include H include H lib local bin H emacs H etc lib man H spool SIC linux tmp home larry joe The initial slash indicates the root directory This signifies the directory called home It is inside the root directory This is the directory larry which is inside home joe is inside larry A path could refer to either a directory or a filename so joe could be either All the items before the short name must be directories An easy way of visualizing this is a tree diagram To see a diagram of a typical LINUX system look at Figure 1 1 Please note that this diagram isn t complete a full LINUX system has over 8000 files and shows only some of the standard directories Thus there may be some directories in that diagram that aren t on your system and your system almost certainly has directories not listed there 1 3 1 Looking at Directories with 1s Now that you know that files and directories exist there must be some way of manipulating them Indeed there is The command 1s is one of the more important ones It lists files If you try ls as a command you ll see home larry 1s 1 3 Storing Information 7 home larry That s right you ll see nothing Unix is intensionally terse it gives you nothing not even no files if the
80. red will save you a lot of typing Emacs usually does completion when you are choosing one item out of some predefined list Everything you learned about moving around and editing text in the first buffer applies to the new one Go ahead and change some text in the new buffer but don t save it i e don t type C x C s Let s assume that you want to discard your changes without saving them in the file The command for that is C x k which kills the buffer Type it now First you will be asked which buffer to kill but the default is the current buffer and that s almost always the one you want to kill so just hit Return Then you will be asked if you really want to kill the buffer Emacs always checks before killing a buffer that has unsaved changes in it Just type yes and hit Return if you want to kill it Go ahead and practice loading in files modifying them saving them and killing their buffers Make sure you don t modify any important system files in a way that will cause trouble of course but do try to have at least five buffers open at once so you can get the hang of switching between them 4 4 Ending an Editing Session When you are done with your work in Emacs make sure that all buffers are saved that should be saved and exit Emacs with C x C c Sometimes C x C c will ask you a question or two in the minibuffer before it lets you leave don t be alarmed just answe
81. rry cat If you now have a cursor on a line by itself you ve done the correct thing There are several variances you could have typed some would work some wouldn t e If you misspelled cat you would have seen nome larry ct ct command not found home larry Thus the shell informs you that it couldn t find a program named ct and gives you another prompt to work with Remember Unix is case sensitive CAT is a misspelling e You could have also placed whitespace before the command like this home larry uuuuucat This produces the correct result and runs the cat program e You might also press return on a line by itself Go right ahead it does absolutely nothing I assume you are now in cat Hopefully you re wondering what it is doing No it is not a game cat is a useful utility that won t seem useful at first Type anything and hit return What you should have seen is home larry cat Help I m stuck in a Linux program Help I m stuck in a Linux program The slanted text indicates what I typed to cat What cat seems to do is echo the text right back at yourself This is useful at times but isn t right now So let s get out of this program and move onto commands that have more obvious benefits To end many Unix commands type Ctrl d 3 Ctrl d is the end of file character or EOF for short Alternatively it stands for end of text depending on what book you read Pll refer to it as an end o
82. sh will find usr bin emacs since that s the only file that begins usr bin ema on my system However if I type usr bin 1d and hit Tab bash beeps at me That s because three files usr bin 1d usr bin 1dd and usr bin 1d86 all start with usr bin 1d on my system If you try a completion and bash beeps you can immediately hit Tab again to get a list of all the files your start matches so far That way if you aren t sure of the exact spelling of your file you can start it and scan a much smaller list of files 3 3 The Standard Input and The Standard Output Let s try to tackle a simple problem getting a listing of the usr bin directory If all we do is 1s usr bin some of the files scroll off the top of the screen How can we see all of the files 3 3 1 Unix Concepts The Unix operating system makes it very easy for programs to use the terminal When a program writes something to your screen it is using something called standard output Standard output abbreviated as stdout is how the program writes things to a user The name for what you tell a program is standard input stdin It s possible for a program to communicate with the user without using standard input or output but most of the commands I cover in this book use stdin and stdout For example the 1s command prints the list of the directories to standard output which is normally connected to your terminal An interactive command su
83. sswd home larry passwd and home larry frog The contents of these three files are the same even if the names aren t cp can copy files between directories if the first parameter is a file and the second parameter is a directory In this case the short name of the file stays the same It can copy a file and change it s name if both parameters are file names Here is one danger of cp If I typed cp etc passwd etc group cp would normally create a new file with the contents identical to passwd and name it group However if etc group already existed cp would destroy the old file without giving you a chance to save it It won t even print out a message reminding you that you re destroying a file by copying over it Let s look at another example of cp home larry ls F frog passwd home larry mkdir passwd_version home larry cp frog passwd passwd_version home larry ls F frog passwd passwd_version home larry ls F passwd_version frog passwd home larry How did I just use cp Evidentally cp can take more than two parameters This is the second line in the command template What the above command did is copied all the files listed frog and passwd and placed them in the passwd version directory In fact cp can take any number of parameters and interprets the first n 1 parameters to be files to copy and the nt parameter as what directory to copy them too You cannot rename files when you copy more than one at
84. tem you will soon learn that the shell s job control is just an interactive version of the function calls fork and execl This is too complex to go into here but may be helpful to remember later on when you are programming and want to run multiple processes from a single program 3 5 Virtual Consoles Being in Many Places at Once Linux supports virtual consoles These are a way of making your single machine seem like multiple terminals all connected to one Linux kernel Thankfully using virtual consoles is one of the simplest things about Linux there are hot keys for switching among the consoles quickly To try it log in to your Linux system hold down the left Alt key and press F2 that is the function key number 2 You should find yourself at another login prompt Don t panic you are now on virtual console VC number 2 Log in here and do some things a few 1s s or whatever to confirm that this is a real login shell Now you can return to VC number 1 by holding down the left Alt and pressing F1 Or you can move on to a third VC in the obvious way Alt F3 Linux systems generally come with four VC s enabled by default You can increase this all the way to eight this should be covered in The Linux System Adminstrator s Guide It involves editing a file in etc or two However four should be enough for most people Once you get used
85. to them VC s will probably become an indispensable tool for getting many things done at once For example I typically run Emacs on VC 1 and do most of my work there while having a communications program up on VC 3 so I can be downloading or uploading files by modem while I work or running jobs on remote machines and keep a shell up on VC 2 just in case I want to run something else without tying up VC 1 7In general it s easier to just kill the job number instead of using PIDs 8Make sure you are doing this from text consoles if you are running X windows or some other graphical application it probably won t work although rumor has it that X Windows will soon allow virtual console switching under Linux Chapter 4 Editing files with Emacs FUNNY SOMETHING OR OTHER 4 1 What s Emacs In order to get anything done on a computer you need a way to put text into files and a way to change text that s already in files An editor is a program for doing this Emacs is one of the most popular editors around partly because it s very easy for a complete beginner to get actual work done with it The classic Unix editor vi is covered in Appendix To learn emacs you need to find a file of plain text letters numbers and the like copy it to your home directory we don t want to modify the actual file if it contains important information and invoke Emacs on the file home larry emacs README Of course if
86. turn 1 4 3 A Forklift Can Be Very Handy mv i old name new name mv j i filel file2 fileN new directory Finally the other file command you should be aware of is mv mv looks a lot like cp except that it deletes the original file after copying it It s a lot like using cp and rm together Let s take a look at what we can do home larry cp etc passwd home larry ls F passwd home larry mv passwd frog home larry ls F frog home larry mkdir report home larry mv frog report home larry ls F report home larry ls F report frog home larry As you can see mv will rename a file if the second parameter is a file If the second parameter is a directory mv will move the file to the new directory keeping it s shortname the same You should be very careful with mv it doesn t check to see if the file already exists and will remove any old file in its way For instance if I had a file named frog already in my directory report the command mv frog report would delete the file report frog and replace it with frog In fact there is one way to make rm cp and mv ask you before deleting files All three of these commands accept the i option which makes them query the user before removing any file If you use an alias you can make the shell do rm i automatically when you type rm You ll learn more about this later in Section on page Chapter 2 The X Window System The nice th
87. u have a large chance of making an error A better way of doing that task is to type home larry report ls F 1993 1 1994 1 data1 data5 1993 2 data new data2 home larry report mkdir backup home larry report cp data backup home larry report ls F backup data new datal data2 data5 home larry report As you can see the asterix told cp to take all of the files beginning with data and copy them to backup Can you guess what cp d w backup would have done 3 1 1 What Really Happens Good question Actually there are a couple of special characters intercepted by the shell bash The character x an asterix says replace this word with all the files that will fit this specification So the command cp data backup like the one above gets changed to cp data new datal data2 data5 backup before it gets run To illustrate this let me introduce a new command echo echo is an extremely simple command it echoes back or prints out any parameters Thus 23 24 Chapter 3 Working with Unix home larry echo Hello Hello home larry echo How are you How are you home larry cd report home larry reporttt ls F 1993 1 1994 1 data1 data5 1993 2 data new data2 home larry report echo 199 1993 1 1993 2 1994 1 home larry report echo 4 1994 1 home larry report echo 2 1993 2 data2 home larry report As you can see the shell expands the wildcard and passes all of the files to
88. uess what M b does That s not all though you can move forward a sentence at a time with M e as long as you write your sentences so that there are always two spaces following the final period otherwise Emacs can t tell where one sentence ends and the next one begins M a is backward sentence If you find yourself using repeated C f s to get to the end of the line be ashamed and make sure that you use C e instead and C a to go to the beginning of the line If you use many C n s to move down screenfuls of text be very ashamed and use C v forever after If you are using repeated C p s to move up screenfuls be embarrassed to show your face and use M v instead If you are nearing the end of a line and you realize that there s a mispelling or a word left out somewhere earlier in the line don t use Backspace or Delete to get back to that spot That would require retyping whole portions of perfectly good text Instead use combinations of M b C b and C f to move to the precise location of the error fix it and then use C e to move to the end of the line again When you have to type in a filename don t ever type in the whole name Just type in enough of it to identify it uniquely and let Emacs s completion finish the job by hitting Tab or Space Why waste keystrokes when you can waste CPU cycles instead If you are typing some kind of plain text and somehow your auto
89. umber and then moves the cursor to that line but how did I find out that function s name This is where Emacs s online help facilities come in Once you have decided what kind of function you are looking for you can use Emacs to track down its exact name Here s one quick and dirty way to do it since Emacs gives completion on function names just type C h f which is describe function remember and then hit Tab without typing anything This asks Emacs to do completion on the empty string in other words the completion will match every single function It may take a moment to build the completion list since Emacs has so many internal functions but it will display as much of it as fits on the screen when it s ready At that point hit C g to quit out of describe function There will be a buffer called Completionsa which contains the completion list you just generated Switch to that buffer Now you can use C s isearch to search for likely functions For example it s a safe assumption that a function which prompts for a line number and then goes to that line will contain the string line in its name Therefore just start searching for the string line and you ll find what you re looking for eventu ally If you want another method you can use C h a command apropos to show all functions whose names match the given string The output of command apropos is a little harder to sort throug
90. ure 2 3 emacs will change its menu bar depending on the type of file you re working on Here is one possible menu bar Buffers Files Tools Edit Search Help Figure 2 4 An Athena type scroll bar is visible on the left of this xterm window Next to it a Motif type scroll bar is visible on the netscape window En su E Es El si Krik pag re 1 haiie that bring up new files and save files By convention this is also the category that contains the command to exit the program To access a command move the mouse cursor over a particular category such as File and press and hold down the left mouse button This will display a variety of commands To select one of the commands move the mouse cursor over that command and release the left mouse button Some menu bars let you click on a category if this is the case clicking on the category will display the menu until you click on either a command another menu or outside the menu bar indicating that you are not interested in running a particular command 2 6 3 Scroll Bars A scroll bar is a method to allow people to display only part of a document while the rest is off the screen For instance the xterm window is currently displaying the bottom third of the text available in Figure 2 4 It s easy to see what part of the available text is current being displayed the darkened part of the scroll bar is relative to both the position and the amount of d
91. would be very inefficient since they are already bound to C n and C p By the way if you look at your mode line after invoking auto fill mode you will notice that the word Fill has been added to the right side As long as it s there Emacs will fill wrap text automatically You can turn it off by typing M x auto fill mode again it s a toggle command The inconvenience of typing long function names in the minibuffer is lessened because Emacs does completion on function names the same way it does on file names Therefore you should rarely find yourself typing in the whole function name letter by letter If you re not sure whether or not you can use completion just hit Tab It can t hurt the worst thing that will happen is that you ll just get a tab character and if you re lucky it ll turn out that you can use completion 4 9 Asking Emacs for Help Emacs has extensive help facilities so extensive in fact that we can only touch on them here The most basic help features are accessed by typing C h and then a single letter For example C h k gets help on a key it prompts you to type a key then tells you what that key does C h t brings up a short Emacs tutorial Most importantly C h C h C h gets you help on help to tell you what s available once you have typed C h the first time If you know the name of an Emacs function save buffer for example but can t remember what key
92. write the buffer s contents into the corresponding file Until you do this the file remains unchanged and the buffer s contents exist only inside of Emacs With that in mind prepare to insert your first character into the buffer Until now everything we have done has been non destructive so this is a big moment You can choose any character you like but if you want to do this in style I suggest using a nice solid capital X As you type it take a look at the beginning of the mode line at the bottom of the screen When you change the buffer so that its contents are no longer the same as those of the file on disk Emacs displays two asterisks at the beginning of the mode line to let you know that the buffer has been modified k Emacs some_file txt Fundamental Top These two asterisks are displayed as soon as you modify the buffer and remain visible until you save the buffer You can save the buffer multiple times during an editing session the command to do so is just C x C s hold down Control and hit x and s while it s down okay so you 2In case you hadn t noticed yet many of Emacs s movement commands consist of combining Control with a single mnemonic letter 4 2 Getting Started Quickly in X 35 probably already figured that out It s deliberately easy to type because saving your buffers is something best done early and often
93. x and extremely powerful It enables one person to copy more information in a second than a fourteenth century monk could do in a year Be careful with cp if you don t have a lot of disk space No one wants to see a Disk full message when working on important files cp can also overwrite existing files without warning I ll talk more about that danger later We ll first talk about the first line in the command template The first parameter to cp is the file to copy the second is where to copy it You can copy to either a different filename or a different directory Let s try some examples home larrytt ls F etc passwd etc passwd home larry cp etc passwd home larry ls F passwd home larry cp passwd frog home larry ls F frog passwd home larry Tcp has two lines in its template because the meaning of the second parameter can be different depending on the number of parameters 1 4 Moving Information 11 The first cp command I ran took the file etc passwd which contains the names of all the users on the Unix system and their encrypted passwords and copied it to my home directory cp doesn t delete the source file so I didn t do anything that could harm the system So two copies of etc passwd exist on my system now both named passwd but one is in the directory etc and one is in home larry Then I created a third copy of etc passwd when I typed cp passwd frog the three copies are now etc pa
94. you decided to copy etc rc etc inittab or any other file substitute that file name for README For instance if you cp etc rc rc then emacs rc Invoking Emacs can have different effects depending on where where you do it From a plain console displaying only text characters Emacs will just take over the whole console If you invoke it from X Emacs will actually bring up its own window I will assume that you are doing it from a text console but everything carries over logically into the X Windows version just substitute the word window in the places I ve written screen Also remeber that you have to move the mouse pointer into Emacs s window to type in it Your screen or window if you re using X should now resemble Figure 4 1 Most of the screen contains your text document but the last two lines are especially interesting if you re trying to learn Emacs The second to last line the one with the long string of dashes is called the mode line In my mode line you see Top It might be All instead and there may be other minor differ ences Many people have the current time displayed in the mode line The line immediately below the mode line is called the minibuffer or sometimes the echo area Emacs uses the minibuffer to flash messages at you and occasionally uses it to read input from you when necessary In fact right now Emacs is telling you For information about the GNU Project and its goa
95. you edit your command line most of them similar to the commands used in GNU Emacs For instance C t flips two adjacent characters You ll be able to find most of the commands in the chapter on Emacs Chapter 4 1 C t means hold down the key labeled Ctrl then press the t key Then release the Ctrl key 3 3 The Standard Input and The Standard Output 25 3 2 2 Command and File Completion Another feature of bash is automatic completion of your command lines For instance let s look at the following example of a typical cp command home larry ls F this is a long file home larry cp this is a long file shorter home larry ls F shorter this is a long file home larry It s a big pain to have to type every letter of this is a long file whenever you try to access it So create this is a long file by copying etc passwd to it Now we re going to do the above cp command very quickly and with a smaller chance of mistyping Instead of typing the whole filename type cp th and press and release the Tab Like magic the rest of the filename shows up on the command line and you can type in shorter Unfortunately bash cannot read your thoughts and you ll have to type all of shorter When you type Tab bash looks at what you ve typed and looks for a file that starts like that For instance if I type usr bin ema and then hit Tab ba

Excerpts from “The Linux Users` Guide”

Contents

Download Pdf Manuals

Related Search

Related Contents

Excerpts from &ldquo;The Linux Users` Guide&rdquo;

Contents

Download Pdf Manuals

Related Search

Related Contents

Excerpts from “The Linux Users` Guide”