MANUAL PAGES(5) BSD File Formats Manual MANUAL PAGES(5)
manpages -- An introduction to manual pages
Manual pages (often shortened to "man pages") are a means of providing
documentation on the command line. Most manual pages describe low-level
programming interfaces, command-line tools, and file formats.
This manual page is intended to help you learn about manual pages, their
purpose, their style, and their overall layout so that you can better
take advantage of the content that they provide.
MANUAL PAGE STYLE
Because manual pages are written by software engineers from many differ-ent different
ent companies and organizations around the world, the format of these
manual pages varies somewhat from page to page, as does the style.
In general, however, manual pages are written to be as concise as possi-ble. possible.
ble. While this makes them a somewhat difficult place to start as a new
programmer, this is intentional. They are not intended to replace con-ceptual conceptual
ceptual documentation such as books on programming. They are intended
primarily to provide a quick reference for people who are already some-what somewhat
what familiar with the subject.
Some manual pages provide links to outside websites. You can often find
more thorough conceptual documentation, sample code, and other useful
information at these websites.
MANUAL PAGE SECTIONS
The manual is divided into sections. Each section covers a particular
subject area. The major manual page sections are:
1 General User Commands
2 System Calls
3 Library Routines (*)
4 Special Files and Sockets
5 File formats and Conventions
6 Games and Fun Stuff
7 Miscellaneous Documentation
8 System Administration
9 Kernel and Programming Style
(*) Excludes library routines that merely wrap system calls. Those rou-tines routines
tines are covered in section 2.
The majority of commonly used commands appear in sections 1 and 8 of the
manual, while most programming information is found in sections 2 and 3.
These subject areas may be further subdivided. For example, manual sec-tion section
tion 3 was originally intended to hold documentation in the standard C
library but has been expanded to include functions in other C language
libraries, such as section 3ssl (OpenSSL functions).
Section 3 has even been expanded to include other programming languages.
For example, section 3pm contains documentation for Perl modules).
It is common to have multiple manual pages with the same name but differ-ent different
ent section numbers. This usually occurs when a command shares a name
with a C function or system call that does something very similar. To
avoid any confusion, manual pages are commonly referred to in the form
name(number), in which the number is the section number.
MANUAL PAGE TOOLS
You can read manual pages in a number of ways. The most common way to
read manual pages is with the man(1) tool from the command line. For
example, typing "man man" displays the manual page for the man tool.
If there are multiple manual pages with the same name but different sec-tion section
tion numbers (for example, open(1) and open(2)), you can specify a sec-tion section
tion number when requesting the page. For example, the command "man 2
open" displays the manual page for the "open" system call from section 2
of the manual.
You can also read manual pages from within Xcode by choosing the "Open
man page..." option in the Help menu, or within your choice of web
browsers by going to <http://developer.apple.com/documentation/Dar-
In addition to searching for manual pages on the web, the manual page
architecture also provides two useful command-line tools for searching
the manual pages: whatis and apropos.
The whatis(1) command searches the manual page headings (command and
function names) for a word. If that word appears in its entirety, it
shows the matching name and abstract. For example, typing "whatis man"
returns results for man and man.conf. This is mostly of interest if you
want to read an abstract for a particular command.
The apropos(1) command is a much more user-friendly version of whatis.
It searches the same database, but searches the manual page abstracts as
well as the titles. Unlike the whatis command, apropos returns results
for partial word matches.
NOTE: Both apropos and whatis depend on a database to provide informa-tion. information.
tion. This database is updated periodically. On fresh installations,
however, it may not be present. If apropos and whatis are not working
correctly, you should run the following command as an admin user:
This will rebuild the database. Enter your admin password when prompted.
MANUAL PAGE STRUCTURE
Manual pages do not have a fixed structure. However, most manual pages
do follow certain conventions.
Manual pages typically begin with a NAME section, which contains the name
of a command or function and a short abstract.
Next, manual pages typically include a SYNOPSIS section, which describes
how to use the command or function. For functions, the syntax generally
contains the necessary include directives, followed by the function dec-larations declarations
larations themselves. For commands, the syntax is explained in MANUAL
After the SYNOPSIS section, you will generally find a DESCRIPTION sec-tion, section,
tion, followed by an OPTIONS section (which explains the flags from the
You may find sections such as ENVIRONMENT HISTORY, BUGS, CONFORMING TO,
AUTHOR, and COPYRIGHT.
Finally, most manual pages end with a section called SEE ALSO, which
includes the names and section numbers of related manual pages.
MANUAL PAGE SYNTAX
In manual page syntax, anything in a normal text font is required text.
Anything in a boldface font is a flag or a subcommand. Anything
underlined is a user-specified argument such as a filename.
Any argument surrounded by brackets is considered to be optional. For
example, [ filename ] would indicate an optional filename argument.
Flags, arguments, or subcommands separated by a vertical separator (|)
are mutually exclusive. For example, if -a turns on an option and -b
turns off the option, the syntax for this command might be -a | -b.
In some cases, you may even see entire groups of arguments wrapped with
brackets and separated by a vertical separator. This is one way of show-ing showing
ing that a command has more than one valid syntax. In other manual
pages, this is expressed by having multiple lines in the synopsis, each
of which begins with the command name. The separated format is more com-mon common
mon (and more readable), but is not always possible for commands with
particularly complex syntax.
Finally, the most important notational convention is the use of the
ellipsis (...). This indicates that additional arguments may be added at
this point. Depending on the author, you may see this written in one of
argument [ argument... ]
For more information on manual pages, see man(1), intro(1), intro(2),
intro(3), intro(5), intro(7), intro(8), intro(9), and the developer docu-mentation documentation
mentation website at <http://developer.apple.com/documentation/Dar-
Mac OS X April 26, 2007 Mac OS X