1 .\" Copyright (c) 2002 Andries Brouwer <aeb@cwi.nl>
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23 .\" 2007-10-23 mtk Added intro paragraph about section, plus a paragraph
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26 .TH INTRO 1 2007-11-15 "Linux" "Linux User's Manual"
28 intro \- Introduction to user commands
30 Section 1 of the manual describes user commands and tools,
31 for example, file manipulation tools, shells, compilers,
32 web browsers, file and image viewers and editors, and so on.
34 All commands yield a status value on termination.
35 This value can be tested (e.g., in most shells the variable
37 contains the status of the last executed command)
38 to see whether the command completed successfully.
39 A zero exit status is conventionally used to indicate success,
40 and a nonzero status means that the command was unsuccessful.
41 (Details of the exit status can be found in
43 A nonzero exit status can be in the range 1 to 255, and some commands
44 use different nonzero status values to indicate the reason why the
47 Linux is a flavor of UNIX, and as a first approximation
48 all user commands under UNIX work precisely the same under
49 Linux (and FreeBSD and lots of other UNIX-like systems).
51 Under Linux there are GUIs (graphical user interfaces), where you
52 can point and click and drag, and hopefully get work done without
53 first reading lots of documentation.
54 The traditional UNIX environment
55 is a CLI (command line interface), where you type commands to
56 tell the computer what to do.
57 That is faster and more powerful,
58 but requires finding out what the commands are.
59 Below a bare minimum, to get started.
61 In order to start working, you probably first have to login,
62 that is, give your username and password.
69 (command interpreter) for you.
70 In case of a graphical login, you get a screen with menus or icons
71 and a mouse click will start a shell in a window.
75 One types commands to the
77 the command interpreter.
78 It is not built-in, but is just a program
79 and you can change your shell.
80 Everybody has her own favorite one.
81 The standard one is called
90 A session might go like
94 .BI "knuth login: " aeb
95 .BI "Password: " ********
97 Tue Aug 6 23:50:44 CEST 2002
111 drwxrwxr\-x 2 aeb 1024 Aug 6 23:51 bin
112 \-rw\-rw\-r\-\- 1 aeb 37 Aug 6 23:52 tel
116 .BI "% " "cp tel tel2"
119 drwxr\-xr\-x 2 aeb 1024 Aug 6 23:51 bin
120 \-rw\-r\-\-r\-\- 1 aeb 37 Aug 6 23:52 tel
121 \-rw\-r\-\-r\-\- 1 aeb 37 Aug 6 23:53 tel2
122 .BI "% " "mv tel tel1"
125 drwxr\-xr\-x 2 aeb 1024 Aug 6 23:51 bin
126 \-rw\-r\-\-r\-\- 1 aeb 37 Aug 6 23:52 tel1
127 \-rw\-r\-\-r\-\- 1 aeb 37 Aug 6 23:53 tel2
128 .BI "% " "diff tel1 tel2"
130 .BI "% " "grep maja tel2"
135 and here typing Control-D ended the session.
138 here was the command prompt\(emit is the shell's way of indicating
139 that it is ready for the next command.
140 The prompt can be customized
141 in lots of ways, and one might include stuff like username,
142 machine name, current directory, time, etc.
143 An assignment PS1="What next, master? "
144 would change the prompt as indicated.
146 We see that there are commands
148 (that gives date and time), and
150 (that gives a calendar).
154 lists the contents of the current directory\(emit tells you what
158 option it gives a long listing,
159 that includes the owner and size and date of the file, and the
160 permissions people have for reading and/or changing the file.
161 For example, the file "tel" here is 37 bytes long, owned by aeb
162 and the owner can read and write it, others can only read it.
163 Owner and permissions can be changed by the commands
170 will show the contents of a file.
171 (The name is from "concatenate and print": all files given as
172 parameters are concatenated and sent to "standard output", here
173 the terminal screen.)
177 (from "copy") will copy a file.
178 On the other hand, the command
180 (from "move") only renames it.
184 lists the differences between two files.
185 Here there was no output because there were no differences.
189 (from "remove") deletes the file, and be careful! it is gone.
190 No wastepaper basket or anything.
195 (from "g/re/p") finds occurrences of a string in one or more files.
196 Here it finds Maja's telephone number.
197 .SS "Pathnames and the current directory"
198 Files live in a large tree, the file hierarchy.
201 describing the path from the root of the tree (which is called /)
203 For example, such a full pathname might be /home/aeb/tel.
204 Always using full pathnames would be inconvenient, and the name
205 of a file in the current directory may be abbreviated by only giving
207 That is why "/home/aeb/tel" can be abbreviated
208 to "tel" when the current directory is "/home/aeb".
212 prints the current directory.
216 changes the current directory.
217 Try "cd /" and "pwd" and "cd" and "pwd".
221 makes a new directory.
225 removes a directory if it is empty, and complains otherwise.
229 (with a rather baroque syntax) will find files with given name
231 For example, "find . \-name tel" would find
232 the file "tel" starting in the present directory (which is called ".").
233 And "find / \-name tel" would do the same, but starting at the root
235 Large searches on a multi-GB disk will be time-consuming,
236 and it may be better to use
238 .SS "Disks and Filesystems"
241 will attach the file system found on some disk (or floppy, or CDROM or so)
242 to the big file system hierarchy.
248 will tell you how much of your disk is still free.
250 On a UNIX system many user and system processes run simultaneously.
251 The one you are talking to runs in the
257 will show you which processes are active and what numbers these
261 allows you to get rid of them.
262 Without option this is a friendly
263 request: please go away.
264 And "kill \-9" followed by the number
265 of the process is an immediate kill.
266 Foreground processes can often be killed by typing Control-C.
267 .SS "Getting information"
268 There are thousands of commands, each with many options.
269 Traditionally commands are documented on
271 (like this one), so that the command "man kill" will document
272 the use of the command "kill" (and "man man" document the command "man").
275 sends the text through some
279 Hit the space bar to get the next page, hit q to quit.
281 In documentation it is customary to refer to man pages
282 by giving the name and section number, as in
284 Man pages are terse, and allow you to find quickly some forgotten
286 For newcomers an introductory text with more examples
287 and explanations is useful.
289 A lot of GNU/FSF software is provided with info files.
291 for an introduction on the use of the program "info".
293 Special topics are often treated in HOWTOs.
295 .I /usr/share/doc/howto/en
296 and use a browser if you find HTML files there.
298 .\" Actual examples? Separate section for each of cat, cp, ...?
299 .\" gzip, bzip2, tar, rpm
projects / thirdparty / man-pages.git / blob