NAME

       apropos - search the manual page names and descriptions

SYNOPSIS

       apropos  [-dalv?V]  [-e|-w|-r] [-s list] [-m system[,...]] [-M path] [-L locale] [-C file]
       keyword ...

DESCRIPTION

       Each manual page has a short  description  available  within  it.   apropos  searches  the
       descriptions for instances of keyword.

       keyword  is  usually  a  regular expression, as if (-r) was used, or may contain wildcards
       (-w), or match the exact keyword (-e).  Using these options, it may be necessary to  quote
       the keyword or escape (\) the special characters to stop the shell from interpreting them.

       The  standard  matching  rules  allow  matches  to  be made against the page name and word
       boundaries in the description.

       The database searched by apropos is updated by  the  mandb  program.   Depending  on  your
       installation, this may be run by a periodic cron job, or may need to be run manually after
       new manual pages have been installed.

OPTIONS

       -d, --debug
              Print debugging information.

       -v, --verbose
              Print verbose warning messages.

       -r, --regex
              Interpret each keyword as a regular expression.  This  is  the  default  behaviour.
              Each  keyword  will  be  matched  against  the  page  names  and  the  descriptions
              independently.  It can match any part of either.  The match is not limited to  word
              boundaries.

       -w, --wildcard
              Interpret each keyword as a pattern containing shell style wildcards.  Each keyword
              will be matched against the page names  and  the  descriptions  independently.   If
              --exact  is also used, a match will only be found if an expanded keyword matches an
              entire description or page name.  Otherwise the keyword is also allowed to match on
              word boundaries in the description.

       -e, --exact
              Each keyword will be exactly matched against the page names and the descriptions.

       -a, --and
              Only display items that match all the supplied keywords.  The default is to display
              items that match any keyword.

       -l, --long
              Do not trim output to the terminal width.  Normally, output will  be  truncated  to
              the terminal width to avoid ugly results from poorly-written NAME sections.

       -s list, --sections=list, --section=list
              Search only the given manual sections.  list is a colon- or comma-separated list of
              sections.  If an entry in list is a simple  section,  for  example  "3",  then  the
              displayed  list  of descriptions will include pages in sections "3", "3perl", "3x",
              and so on; while if an entry in list has an extension, for  example  "3perl",  then
              the list will only include pages in that exact part of the manual section.

       -m system[,...], --systems=system[,...]
              If  this  system  has  access to other operating systems' manual page descriptions,
              they  can  be  searched  using  this  option.   To  search  NewOS's   manual   page
              descriptions, use the option -m NewOS.

              The  system  specified  can  be  a  combination of comma-delimited operating system
              names.  To include a search of the native operating system's  whatis  descriptions,
              include  the system name man in the argument string.  This option will override the
              $SYSTEM environment variable.

       -M path, --manpath=path
              Specify an alternate set of colon-delimited manual page hierarchies to search.   By
              default,  apropos  uses  the  $MANPATH  environment variable, unless it is empty or
              unset, in which case it will determine an appropriate manpath based on  your  $PATH
              environment variable.  This option overrides the contents of $MANPATH.

       -L locale, --locale=locale
              apropos  will  normally  determine  your current locale by a call to the C function
              setlocale(3) which interrogates various environment variables,  possibly  including
              $LC_MESSAGES  and  $LANG.   To  temporarily override the determined value, use this
              option to supply a locale string directly to apropos.  Note that it will  not  take
              effect until the search for pages actually begins.  Output such as the help message
              will always be displayed in the initially determined locale.

       -C file, --config-file=file
              Use this user configuration file rather than the default of ~/.manpath.

       -?, --help
              Print a help message and exit.

       --usage
              Print a short usage message and exit.

       -V, --version
              Display version information.

EXIT STATUS

       0      Successful program execution.

       1      Usage, syntax or configuration file error.

       2      Operational error.

       16     Nothing was found that matched the criteria specified.

ENVIRONMENT

       SYSTEM If $SYSTEM is set, it will have the same effect as if it had been specified as  the
              argument to the -m option.

       MANPATH
              If  $MANPATH  is  set,  its value is interpreted as the colon-delimited manual page
              hierarchy search path to use.

              See the SEARCH PATH section of manpath(5) for the default behaviour and details  of
              how this environment variable is handled.

       MANWIDTH
              If  $MANWIDTH  is  set,  its  value  is  used as the terminal width (see the --long
              option).  If it is not set, the terminal width will be calculated using  the  value
              of  $COLUMNS,  and  ioctl(2)  if available, or falling back to 80 characters if all
              else fails.

       POSIXLY_CORRECT
              If $POSIXLY_CORRECT is set, even to a null value, the default apropos  search  will
              be as an extended regex (-r).  Nowadays, this is the default behaviour anyway.

FILES

       /usr/share/man/index.(bt|db|dir|pag)
              A traditional global index database cache.

       /var/cache/man/index.(bt|db|dir|pag)
              An FHS compliant global index database cache.

       /usr/share/man/.../whatis
              A traditional whatis text database.

SEE ALSO

       man(1), whatis(1), mandb(8)

AUTHOR

       Wilf. (G.Wilford@ee.surrey.ac.uk).
       Fabrizio Polacco (fpolacco@debian.org).
       Colin Watson (cjwatson@debian.org).

BUGS

       https://gitlab.com/cjwatson/man-db/-/issues
       https://savannah.nongnu.org/bugs/?group=man-db