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>.

Debian				October 1, 2020				Debian