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man – Display A Program's Manual Page
Most executable programs intended for command line use provide a formal piece of doc- umentation called a manual or man page. A special paging program called man is used to view them. It is used like this:
man program
man program
where “program” is the name of the command to view.
Man pages vary somewhat in format but generally contain a title, a synopsis of the com - mand's syntax, a description of the command's purpose, and a listing and description of each of the command's options. Man pages, however, do not usually include examples, and are intended as a reference, not a tutorial. As an example, let's try viewing the man page for the ls command:
[me@linuxbox ~]$ man ls
[me@linuxbox ~]$ man ls
On most Linux systems, man uses less to display the manual page, so all of the familiar
less commands work while displaying the page.
The “manual” that man displays is broken into sections and not only covers user com- mands but also system administration commands, programming interfaces, file formats and more. The table below describes the layout of the manual:
Table 5-1: Man Page Organization
Section Contents
Section Contents
1 User commands
2 Programming interfaces for kernel system calls
3 Programming interfaces to the C library
4 Special files such as device nodes and drivers
5 File formats
6 Games and amusements such as screen savers
7 Miscellaneous
8 System administration commands
Sometimes we need to look in a specific section of the manual to find what we are look- ing for. This is particularly true if we are looking for a file format that is also the name of a command. Without specifying a section number, we will always get the first instance of a match, probably in section 1. To specify a section number, we use man like this:
man section search_term
man section search_term
For example:
[me@linuxbox ~]$ man 5 passwd
[me@linuxbox ~]$ man 5 passwd
This will display the man page describing the file format of the /etc/passwd file.