apropos(1) - search the manual page names and descriptions
-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  system's  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.
-h, --help
       Print a help message and exit.
-V, --version
       Display version information.