LINUX
COMMANDS
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Command-line help
To many the online help in Linux offered by the info and
man pages will appear terse and cryptic. That's because
they act more as a quick reference, than a full tutorial.
--help
The --help option displays a fairly brief list
of a command or program's options for many commands or programs,
e.g.:
ls --help
$ info
The info command will give you help with many
of the commands and programs in Linux.
info
Display the main menu.
Info keys
To select a menu option, move the cursor with the cursor
keys, and press Enter to select an option.
Key |
Description |
Enter |
select menu option, indicated by a preceding asterix
(*) |
u |
up a node (i.e. opposite of Enter) |
q |
quit |
info ls
Display the main info page for the ls command.
info bash
Display the main info page for the bash shell.
$ man - manual
Man (manual) pages, unlike info pages, display everything
on one page, making them handy to quickly find a command
option.
man ls
Display the ls man page.
Key |
Description |
Down cursor |
Down a line. |
Up cursor |
Up a line. |
Space |
Down a screen. |
b |
Back a screen. |
q |
Quit. |
The man database
The title and brief description of each man page is stored
in a simple database with the one-line format:
title (section) -
description
The sections are as follows:
Section |
Topic |
1 |
Utilities and shell commands. |
2 |
System calls. |
3 |
Library calls. |
4 |
Device and other special files. |
5 |
File formats. |
6 |
Games. |
7 |
Macro packages. |
8 |
System administration commands. |
9 |
Kernel routines. |
man 1 -K process
Search all of each section 1 man page (utilities and shell
commands) for the string, 'process', and for each match,
prompt to view.
$ whatis
whatis ls
Display a brief description of the ls command.
Note:
whatis works by searching the man database for
the complete word 'ls' in the title section, and
displays the results.
$ apropos
apropos file
Display a list of man pages concerning files.
Note:
apropos works by searching the man database for
the string 'file' in the title, section, and description
sections, and displays the results.
$ which
which cat
Displays any aliases a program (in this case cat)
has, followed by where the program is located (by searching
your PATH for executable files).
$ whereis
whereis cat
Displays where a program is located, followed by where its
man page is located.
/usr/doc and /usr/share/doc
When software is installed, documentation other than man
and info pages is stored in either the /usr/doc
and /usr/share/doc directories. This you can browse
from the command-line with the text-only Internet browser,
Lynx.
lynx /usr/share/doc
Browse the documentation in the /usr/share/doc
directory.
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