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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>.