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] 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 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.
-?, --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.
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, an 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).
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
