Manual Page Search Parameters

APROPOS(1) General Commands Manual APROPOS(1)


apropos, whatissearch manual page databases


apropos [-afk] [-C file] [-M path] [-m path] [-O outkey] [-S arch] [-s section] expression ...


The apropos and whatis utilities query manual page databases generated by makewhatis(8), evaluating expression for each file in each database. By default, they display the names, section numbers, and description lines of all matching manuals.
By default, apropos searches for makewhatis(8) databases in the default paths stipulated by man(1) and uses case-insensitive substring matching (the = operator) over manual names and descriptions (the Nm and Nd macro keys). Multiple terms imply pairwise -o.
whatis is a synonym for apropos -f.
The options are as follows:
Instead of showing only the title lines, show the complete manual pages, just like man(1) -a would. If the standard output is a terminal device and -c is not specified, use more(1) to paginate them. In -a mode, the options -IKOTW described in the mandoc(1) manual are also available.
-C file
Specify an alternative configuration file in man.conf(5) format.
Search for all words in expression in manual page names only. The search is case insensitive and matches whole words only. In this mode, macro keys, comparison operators, and logical operators are not available.
Support the full expression syntax. It is the default for apropos.
-M path
Use the colon-separated path instead of the default list of paths searched for makewhatis(8) databases. Invalid paths, or paths without manual databases, are ignored.
-m path
Prepend the colon-separated paths to the list of paths searched for makewhatis(8) databases. Invalid paths, or paths without manual databases, are ignored.
-O outkey
Show the values associated with the key outkey instead of the manual descriptions.
-S arch
Restrict the search to pages for the specified machine(1) architecture. arch is case insensitive. By default, pages for all architectures are shown.
-s section
Restrict the search to the specified section of the manual. By default, pages from all sections are shown. See man(1) for a listing of sections.
The options -chlw are also supported and are documented in man(1). The options -fkl are mutually exclusive and override each other.
An expression consists of search terms joined by logical operators -a (and) and -o (or). The -a operator has precedence over -o and both are evaluated left-to-right.
( expr )
True if the subexpression expr is true.
expr1 -a expr2
True if both expr1 and expr2 are true (logical ‘and’).
expr1 [-o] expr2
True if expr1 and/or expr2 evaluate to true (logical ‘or’).
True if term is satisfied. This has syntax [[key[,key...]](=|~)]val, where key is an mdoc(7) macro to query and val is its value. See Macro Keys for a list of available keys. Operator = evaluates a substring, while ~ evaluates a regular expression.
-i term
If term is a regular expression, it is evaluated case-insensitively. Has no effect on substring terms.
Results are sorted according to the following criteria:
  1. The manpath directory tree the page is found in, according to the order specified with -M, -m, the MANPATH environment variable, the man.conf(5) configuration file, or the default documented in man.conf(5).
  2. The section number in ascending numerical order.
  3. The page name in ascending ascii(7) alphabetical order, case-insensitive.
Each output line is formatted as
name[, name...](sec) - description
Where “name” is the manual's name, “sec” is the manual section, and “description” is the manual's short description. If an architecture is specified for the manual, it is displayed as
name(sec/arch) - description
Resulting manuals may be accessed as
$ man -s sec name
If an architecture is specified in the output, use
$ man -s sec -S arch name

Macro Keys

Queries evaluate over a subset of mdoc(7) macros indexed by makewhatis(8). In addition to the macro keys listed below, the special key any may be used to match any available macro key.
Names and description:
Nm manual name
Nd one-line manual description
arch machine architecture (case-insensitive)
sec manual section number
Sections and cross references:
Sh section header (excluding standard sections)
Ss subsection header
Xr cross reference to another manual page
Rs bibliographic reference
Semantic markup for command line utilities:
Fl command line options (flags)
Cm command modifier
Ar command argument
Ic internal or interactive command
Ev environmental variable
Pa file system path
Semantic markup for function libraries:
Lb function library name
In include file
Ft function return type
Fn function name
Fa function argument type and name
Vt variable type
Va variable name
Dv defined variable or preprocessor constant
Er error constant
Ev environmental variable
Various semantic markup:
An author name
Lk hyperlink
Mt “mailto” hyperlink
Cd kernel configuration declaration
Ms mathematical symbol
Tn tradename
Physical markup:
Em italic font or underline
Sy boldface font
Li typewriter font
Text production:
St reference to a standards document
At AT&T UNIX version reference
Bx BSD version reference
Bsx BSD/OS version reference
Nx NetBSD version reference
Fx FreeBSD version reference
Ox OpenBSD version reference
Dx DragonFly version reference


Any non-empty value of the environment variable MANPAGER is used instead of the standard pagination program, more(1); see man(1) for details. Only used if -a or -l is specified.
A colon-separated list of directories to search for manual pages; see man(1) for details. Overridden by -M, ignored if -l is specified.
Specifies the pagination program to use when MANPAGER is not defined. If neither PAGER nor MANPAGER is defined, more(1) -s is used. Only used if -a or -l is specified.


name of the makewhatis(8) keyword database
default man(1) configuration file


The apropos utility exits 0 on success, and >0 if an error occurs.


Search for “.cf” as a substring of manual names and descriptions:
$ apropos .cf
Include matches for “.cnf” and “.conf” as well:
$ apropos .cf .cnf .conf
Search in names and descriptions using a regular expression:
$ apropos '~set.?[ug]id'
Search for manuals in the library section mentioning both the “optind” and the “optarg” variables:
$ apropos -s 3 Va=optind -a Va=optarg
Do exactly the same as calling whatis(1) with the argument “ssh”:
$ apropos -- -i 'Nm~[[:<:]]ssh[[:>:]]'
The following two invocations are equivalent:
$ apropos -S arch -s section expression
$ apropos \( expression \) -a arch~^(arch|any)$ -a sec~^section$


man(1), re_format(7), makewhatis(8)


Part of the functionality of whatis was already provided by the former manwhere utility in 1BSD. The apropos and whatis utilities first appeared in 2BSD. They were rewritten from scratch for OpenBSD 5.6.
The -M option and the MANPATH variable first appeared in 4.3BSD; -m in 4.3BSD-Reno; -C in 4.4BSD-Lite1; and -S and -s in OpenBSD 4.5 for apropos and in OpenBSD 5.6 for whatis. The options -acfhIKklOTWw appeared in OpenBSD 5.7.


Bill Joy wrote manwhere in 1977 and the original BSD apropos and whatis in February 1979. The current version was written by Kristaps Dzonsons <kristaps@bsd.lv> and Ingo Schwarze <schwarze@openbsd.org>.
March 27, 2017 OpenBSD-6.1