apropos, whatis — search manual page databases

       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                                      APROPOS(1)

       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.

       -Cfile
               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.

       -Mpath
               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.

       -mpath
               Prepend  the  colon-separated  paths  to  the list of paths searched for makewhatis(8) databases.
               Invalid paths, or paths without manual databases, are ignored.

       -Ooutkey
               Show the values associated with the key outkey instead of the manual descriptions.

       -Sarch
               Restrict the  search  to  pages  for  the  specified  machine(1)  architecture.   arch  is  case-
               insensitive.  By default, pages for all architectures are shown.

       -ssection
               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-aexpr2
               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.

       -iterm
               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-ssecname

       If an architecture is specified in the output, use

             $man-ssec-SarchnameMacroKeys
       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

       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.

       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-s9.

       Search for manuals in the library section mentioning both the "optind" and the "optarg" variables:

             $apropos-s3Va=optind-aVa=optarg

       Do exactly the same as calling whatis with the argument "ssh":

             $apropos---i'Nm~[[:<:]]ssh[[:>:]]'

       The following two invocations are equivalent:

             $apropos-Sarch-ssectionexpression$apropos\(expression\)-aarch~^(arch|any)$-asec~^section$

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

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

       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.

       apropos, whatis — search manual page databases

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

       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.

apropos [-afk] [-Cfile] [-Mpath] [-mpath] [-Ooutkey] [-Sarch] [-ssection] expression...