In
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...
, is a command to search the
man page
A man page (short for manual page) is a form of software documentation usually found on a Unix or Unix-like operating system. Topics covered include computer programs (including library and system calls), formal standards and conventions, and e ...
files in
Unix
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, an ...
and
Unix-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
operating systems. Apropos takes its name from the French "
à propos
À, à ( a-grave) is a letter of the Catalan, Emilian-Romagnol, French, Galician, Italian, Maltese, Occitan, Portuguese, Sardinian, Scottish Gaelic, Vietnamese, and Welsh languages consisting of the letter A of the ISO basic Latin alpha ...
" (Latin "ad prōpositum") which means ''about''. It is particularly useful when searching for commands without knowing their exact names.
Behavior
Often a wrapper for the command, the apropos command is used to search the "name" sections of all manual pages for the string/s (called keyword/s) specified. The output is a list of all manual pages containing the search term in their name or description. This is often useful if one knows the action that is desired, but does not remember the exact command or page name. apropos search is case insensitive.
usually searches in a precompiled database that is shared with , a command for obtaining the brief description of a specific command whose exact name is already known.
Sample usage
The following example demonstrates the output of the command:
$ apropos mount
free (1) - Display amount of free and used memory in the system
mklost+found (8) - create a lost+found directory on a mounted Linux second extended file system
mount (8) - mount a file system
mountpoint (1) - see if a directory is a mountpoint
ntfsmount (8) - Read/Write userspace NTFS driver.
sleep (1) - delay for a specified amount of time
switch_root (8) - switch to another filesystem as the root of the mount tree.
umount (8) - unmount file systems
In this example, is used to search for the keyword "mount", and returns the indicated man pages that include the term "mount".
The following example demonstrates the output of the command with an regexp keyword (abc.n) and a regular keyword:
$ apropos abc.n xzless
XTestGrabControl (3) - XTest extension functions
xzless (1) - view xz or lzma compressed (text) files
In this example, is used to search for the keywords (with an regexp .) "abc.n" and xzless, and returns the indicated man pages that include the keywords.
Related utilities
is a command for obtaining the brief description of a specific command whose exact name is already known. It uses the same database as does. On systems with
mandoc
mandoc (historically called mdocml) is a utility used for formatting man pages in BSD Operating Systems (e.g. NetBSD), specifically those written in the ''mdoc'' and ''man'' macro languages. Unlike the groff and older troff and nroff tools tha ...
, it is a wrapper for (search by name only).
$ whatis whatis
whatis(1) - search the whatis database for complete words
is a command for indexing all on-disk manuals into a database that and can read from. It first appeared in the
2BSD of 1979, but has since been rewritten multiple times in different implementations of .
is a command that performs the same function in man-db.
The database is traditionally plain text, but man-db, the implementation found on many
Linux distributions, use a
Berkeley DB
Berkeley DB (BDB) is an unmaintained embedded database software library for key/value data, historically significant in open source software. Berkeley DB is written in C with API bindings for many other programming languages. BDB stores arbitr ...
instead.
The mandoc
mandoc (historically called mdocml) is a utility used for formatting man pages in BSD Operating Systems (e.g. NetBSD), specifically those written in the ''mdoc'' and ''man'' macro languages. Unlike the groff and older troff and nroff tools tha ...
implementation used on many BSD distributions likewise has its own innovations on the format.
See also
* Man page
A man page (short for manual page) is a form of software documentation usually found on a Unix or Unix-like operating system. Topics covered include computer programs (including library and system calls), formal standards and conventions, and e ...
* whatis
References
External links
*
*
*
at the LinuxQuestions.org wiki
{{Unix commands
Unix text processing utilities