APROPOS(1) | General Commands Manual | APROPOS(1)

# NAME

`apropos`, `whatis` — search manual page databases

# SYNOPSIS

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

# DESCRIPTION

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 extended regular expression matching 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:

`-a`
  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 less(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.
`-f`
  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.
`-k`
  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’).
term
  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 case-sensitive extended regular expression.
`-i` term
  If term is a regular expression, it is evaluated case-insensitively. Has no effect on substring terms.

Results are sorted first according to the section number in ascending numerical order, then by 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

In general, macro keys are supposed to yield complete results without expecting the user to consider actual macro usage. For example, results include:

`Fa`
  function arguments appearing on `Fn` lines
`Fn`
  function names marked up with `Fo` macros
`In`
  include file names marked up with `Fd` macros
`Vt`
  types appearing as function return types and
  types appearing in function arguments in the SYNOPSIS

# ENVIRONMENT

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

# FILES

mandoc.db
  name of the makewhatis(8) keyword database
/etc/man.conf
  default man(1) configuration file

# EXIT STATUS

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

# EXAMPLES

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 case-sensitive regular expression:

`$ apropos '~set.?[ug]id'`

Search for all manual pages in a given section:

`$ apropos -s 9 .`

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` 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)$` `-a sec~^`section`$`

# SEE ALSO

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

# STANDARDS

The `apropos` utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification of man(1) `-k`.

All options, the `whatis` command, support for logical operators, macro keys, substring matching, sorting of results, the environment variables `MANPAGER` and `MANPATH`, the database format, and the configuration file are extensions to that specification.

# HISTORY

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.

# AUTHORS

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>.

October 1, 2020 | Debian