Almost all substantial UNIX and Unix-like operating systems have extensive documentation known as man pages (short for "manual pages"). The Unix command used to display them is
man. Each page is a self-contained document. The
man command is analogous to the
help command in the command shells of DOS, OS/2 and Microsoft Windows.
Pages are traditionally referred to using the notation "name(section)"; for example, . The same page name may appear in more than one section of the manual, this can occur when the names of system calls, user commands, or macro packages conflict. Two examples are and , or and . The syntax for accessing the non-default manual section varies between different man implementations. On Linux and *BSD, for example, the syntax for reading is
man 3 printf
manhave enjoyed much popularity, with the possible exception of the GNU project's "
info" system, an early and simple hypertext system.
However, the format of a single page for each application, the lack of classification within the sections and the relatively unsophisticated formatting facilities have motivated the development of alternative documentation systems, such as the previously mentioned
Most Unix GUI applications (particularly those built using the GNOME and KDE development environments) now provide end-user documentation in HTML and include embedded HTML viewers such as
yelp for reading the help within the application.
Usually the man pages are written in English. Translations into other languages can be also available on the system.
The default format of the man pages is troff, with either the macro package man (appearance oriented) or on some systems mdoc (semantic oriented). This makes it possible to typeset a man page to PostScript, PDF and various other formats for viewing or printing.
|3||C library functions|
|4||Special files (usually devices, those found in /dev) and drivers|
|5||File formats and conventions|
|6||Games and screensavers|
|8||System administration commands and daemons|
Unix System V uses a similar numbering scheme, except section 4 is file formats, section 5 is miscellany and section 7 is special files.
On some systems some of the following sections are available:
|0||C library header files|
|x||The X Window System|
The sections are further subdivided by means of a suffix letter, such that section 3C is for C library calls, 3M is for the math library, and so on. A consequence of this is that section 8 (system administration commands) is sometimes relegated to the 1M subsection of the main commands section. Some subsection suffixes have a general meaning across sections:
|x||X Window System documentation|
Some versions of man cache the formatted versions of the last several pages viewed.
To see options you can use with command man, enter the command man man.
Other sections may be present, but these are not well standardized across man pages. Common examples include: OPTIONS, EXIT STATUS, ENVIRONMENT, KNOWN BUGS, FILES, AUTHOR, REPORTING BUGS, HISTORY and COPYRIGHT.