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
Print debugging information.
Print verbose warning messages.
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
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
Each keyword will be exactly matched against the page names
and the descriptions.
Only display items that match all the supplied keywords. The
default is to display items that match any keyword.
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 -mNewOS.
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=localeapropos 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
Print a help message and exit.
Print a short usage message and exit.
Display version information.
SYSTEM If $SYSTEM is set, it will have the same effect as if it had
been specified as the argument to the -m option.
If $MANPATH is set, its value is interpreted as the colon-
delimited manual page hierarchy search path to use.
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, an ioctl(2) if
available, or falling back to 80 characters if all else fails.
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.
A traditional global index database cache.
An FHS compliant global index database cache.
A traditional whatis text database.
This page is part of the man-db (manual pager suite) project.
Information about the project can be found at
⟨http://www.nongnu.org/man-db/⟩. If you have a bug report for this
manual page, send it to firstname.lastname@example.org. This page was
obtained from the project's upstream Git repository
⟨http://git.savannah.gnu.org/r/man-db.git⟩ on 2016-08-07. If you dis‐
cover any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
2.7.5 2015-11-06 APROPOS(1)