1 .\" Copyright (c) 2002 Andries Brouwer <aeb@cwi.nl>
3 .\" %%%LICENSE_START(VERBATIM)
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25 .\" 2007-10-23 mtk Added intro paragraph about section, plus a paragraph
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28 .TH INTRO 1 2007-11-15 "Linux" "Linux User's Manual"
30 intro \- introduction to user commands
32 Section 1 of the manual describes user commands and tools,
33 for example, file manipulation tools, shells, compilers,
34 web browsers, file and image viewers and editors, and so on.
36 All commands yield a status value on termination.
37 This value can be tested (e.g., in most shells the variable
39 contains the status of the last executed command)
40 to see whether the command completed successfully.
41 A zero exit status is conventionally used to indicate success,
42 and a nonzero status means that the command was unsuccessful.
43 (Details of the exit status can be found in
45 A nonzero exit status can be in the range 1 to 255, and some commands
46 use different nonzero status values to indicate the reason why the
49 Linux is a flavor of UNIX, and as a first approximation
50 all user commands under UNIX work precisely the same under
51 Linux (and FreeBSD and lots of other UNIX-like systems).
53 Under Linux, there are GUIs (graphical user interfaces), where you
54 can point and click and drag, and hopefully get work done without
55 first reading lots of documentation.
56 The traditional UNIX environment
57 is a CLI (command line interface), where you type commands to
58 tell the computer what to do.
59 That is faster and more powerful,
60 but requires finding out what the commands are.
61 Below a bare minimum, to get started.
63 In order to start working, you probably first have to login,
64 that is, give your username and password.
71 (command interpreter) for you.
72 In case of a graphical login, you get a screen with menus or icons
73 and a mouse click will start a shell in a window.
77 One types commands to the
79 the command interpreter.
80 It is not built-in, but is just a program
81 and you can change your shell.
82 Everybody has her own favorite one.
83 The standard one is called
92 A session might go like
96 .BI "knuth login: " aeb
97 .BI "Password: " ********
99 Tue Aug 6 23:50:44 CEST 2002
113 drwxrwxr\-x 2 aeb 1024 Aug 6 23:51 bin
114 \-rw\-rw\-r\-\- 1 aeb 37 Aug 6 23:52 tel
118 .BI "% " "cp tel tel2"
121 drwxr\-xr\-x 2 aeb 1024 Aug 6 23:51 bin
122 \-rw\-r\-\-r\-\- 1 aeb 37 Aug 6 23:52 tel
123 \-rw\-r\-\-r\-\- 1 aeb 37 Aug 6 23:53 tel2
124 .BI "% " "mv tel tel1"
127 drwxr\-xr\-x 2 aeb 1024 Aug 6 23:51 bin
128 \-rw\-r\-\-r\-\- 1 aeb 37 Aug 6 23:52 tel1
129 \-rw\-r\-\-r\-\- 1 aeb 37 Aug 6 23:53 tel2
130 .BI "% " "diff tel1 tel2"
132 .BI "% " "grep maja tel2"
137 and here typing Control-D ended the session.
140 here was the command prompt\(emit is the shell's way of indicating
141 that it is ready for the next command.
142 The prompt can be customized
143 in lots of ways, and one might include stuff like username,
144 machine name, current directory, time, and so on.
145 An assignment PS1="What next, master? "
146 would change the prompt as indicated.
148 We see that there are commands
150 (that gives date and time), and
152 (that gives a calendar).
156 lists the contents of the current directory\(emit tells you what
160 option it gives a long listing,
161 that includes the owner and size and date of the file, and the
162 permissions people have for reading and/or changing the file.
163 For example, the file "tel" here is 37 bytes long, owned by aeb
164 and the owner can read and write it, others can only read it.
165 Owner and permissions can be changed by the commands
172 will show the contents of a file.
173 (The name is from "concatenate and print": all files given as
174 parameters are concatenated and sent to "standard output", here
175 the terminal screen.)
179 (from "copy") will copy a file.
180 On the other hand, the command
182 (from "move") only renames it.
186 lists the differences between two files.
187 Here there was no output because there were no differences.
191 (from "remove") deletes the file, and be careful! it is gone.
192 No wastepaper basket or anything.
197 (from "g/re/p") finds occurrences of a string in one or more files.
198 Here it finds Maja's telephone number.
199 .SS Pathnames and the current directory
200 Files live in a large tree, the file hierarchy.
203 describing the path from the root of the tree (which is called /)
205 For example, such a full pathname might be /home/aeb/tel.
206 Always using full pathnames would be inconvenient, and the name
207 of a file in the current directory may be abbreviated by giving
208 only the last component.
209 That is why "/home/aeb/tel" can be abbreviated
210 to "tel" when the current directory is "/home/aeb".
214 prints the current directory.
218 changes the current directory.
219 Try "cd /" and "pwd" and "cd" and "pwd".
223 makes a new directory.
227 removes a directory if it is empty, and complains otherwise.
231 (with a rather baroque syntax) will find files with given name
233 For example, "find . \-name tel" would find
234 the file "tel" starting in the present directory (which is called ".").
235 And "find / \-name tel" would do the same, but starting at the root
237 Large searches on a multi-GB disk will be time-consuming,
238 and it may be better to use
240 .SS Disks and filesystems
243 will attach the filesystem found on some disk (or floppy, or CDROM or so)
244 to the big filesystem hierarchy.
250 will tell you how much of your disk is still free.
252 On a UNIX system many user and system processes run simultaneously.
253 The one you are talking to runs in the
259 will show you which processes are active and what numbers these
263 allows you to get rid of them.
264 Without option this is a friendly
265 request: please go away.
266 And "kill \-9" followed by the number
267 of the process is an immediate kill.
268 Foreground processes can often be killed by typing Control-C.
269 .SS Getting information
270 There are thousands of commands, each with many options.
271 Traditionally commands are documented on
273 (like this one), so that the command "man kill" will document
274 the use of the command "kill" (and "man man" document the command "man").
277 sends the text through some
281 Hit the space bar to get the next page, hit q to quit.
283 In documentation it is customary to refer to man pages
284 by giving the name and section number, as in
286 Man pages are terse, and allow you to find quickly some forgotten
288 For newcomers an introductory text with more examples
289 and explanations is useful.
291 A lot of GNU/FSF software is provided with info files.
293 for an introduction on the use of the program "info".
295 Special topics are often treated in HOWTOs.
297 .I /usr/share/doc/howto/en
298 and use a browser if you find HTML files there.
300 .\" Actual examples? Separate section for each of cat, cp, ...?
301 .\" gzip, bzip2, tar, rpm
305 This page is part of release 3.79 of the Linux
308 A description of the project,
309 information about reporting bugs,
310 and the latest version of this page,
312 \%http://www.kernel.org/doc/man\-pages/.
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