apropos(1) - man - phpman

Che Dong

⚡ TLDR: apropos (tldr-pages)

Search the manual pages for names and descriptions.

Search for a keyword using a `regex`
apropos {{regex}}
Search without restricting the output to the terminal width (long output)
apropos {{-l|--long}} {{regex}}
Search for pages that match all the `regex` given
apropos {{regex_1}} {{-a|--and}} {{regex_2}} {{-a|--and}} {{regex_3}}

APROPOS(1) Manual pager utils APROPOS(1)

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] key‐
word ...

DESCRIPTION
Each manual page has a short description available within it. apropos searches the descrip‐
tions 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 key‐
word 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 bound‐
aries in the description.

The database searched by apropos is updated by the mandb program. Depending on your instal‐
lation, this may be run by a periodic cron job, or may need to be run manually after new man‐
ual 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 de‐
scription or page name. Otherwise the keyword is also allowed to match on word bound‐
aries 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 dis‐
played 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 envi‐
ronment variable.

-M path, --manpath=path
Specify an alternate set of colon-delimited manual page hierarchies to search. By de‐
fault, 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 setlo‐‐
cale(3) which interrogates various environment variables, possibly including $LC_MES‐‐
SAGES 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 ar‐
gument to the -m option.

MANPATH
If $MANPATH is set, its value is interpreted as the colon-delimited manual page hier‐
archy 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.