Provided by: man-db_2.12.1-3_amd64 
NAME
man - an interface to the system reference manuals
SYNOPSIS
man [man options] [[section] page ...] ...
man -k [apropos options] regexp ...
man -K [man options] [section] term ...
man -f [whatis options] page ...
man -l [man options] file ...
man -w|-W [man options] page ...
DESCRIPTION
man is the system's manual pager. Each page argument given to man is normally the name of a program,
utility or function. The manual page associated with each of these arguments is then found and
displayed. A section, if provided, will direct man to look only in that section of the manual. The
default action is to search in all of the available sections following a pre-defined order (see
DEFAULTS), and to show only the first page found, even if page exists in several sections.
The table below shows the section numbers of the manual followed by the types of pages they contain.
1 Executable programs or shell commands
2 System calls (functions provided by the kernel)
3 Library calls (functions within program libraries)
4 Special files (usually found in /dev)
5 File formats and conventions, e.g. /etc/passwd
6 Games
7 Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7), man-pages(7)
8 System administration commands (usually only for root)
9 Kernel routines [Non standard]
A manual page consists of several sections.
Conventional section names include NAME, SYNOPSIS, CONFIGURATION, DESCRIPTION, OPTIONS, EXIT STATUS,
RETURN VALUE, ERRORS, ENVIRONMENT, FILES, VERSIONS, STANDARDS, NOTES, BUGS, EXAMPLE, AUTHORS, and
SEE ALSO.
The following conventions apply to the SYNOPSIS section and can be used as a guide in other sections.
bold text type exactly as shown.
italic text replace with appropriate argument.
[-abc] any or all arguments within [ ] are optional.
-a|-b options delimited by | cannot be used together.
argument ... argument is repeatable.
[expression] ... entire expression within [ ] is repeatable.
Exact rendering may vary depending on the output device. For instance, man will usually not be able to
render italics when running in a terminal, and will typically use underlined or coloured text instead.
The command or function illustration is a pattern that should match all possible invocations. In some
cases it is advisable to illustrate several exclusive invocations as is shown in the SYNOPSIS section of
this manual page.
EXAMPLES
man ls
Display the manual page for the item (program) ls.
man man.7
Display the manual page for macro package man from section 7. (This is an alternative spelling of
"man 7 man".)
man 'man(7)'
Display the manual page for macro package man from section 7. (This is another alternative spelling
of "man 7 man". It may be more convenient when copying and pasting cross-references to manual pages.
Note that the parentheses must normally be quoted to protect them from the shell.)
man -a intro
Display, in succession, all of the available intro manual pages contained within the manual. It is
possible to quit between successive displays or skip any of them.
man -t bash | lpr -Pps
Format the manual page for bash into the default troff or groff format and pipe it to the printer
named ps. The default output for groff is usually PostScript. man --help should advise as to which
processor is bound to the -t option.
man -l -Tdvi ./foo.1x.gz > ./foo.1x.dvi
This command will decompress and format the nroff source manual page ./foo.1x.gz into a device
independent (dvi) file. The redirection is necessary as the -T flag causes output to be directed to
stdout with no pager. The output could be viewed with a program such as xdvi or further processed
into PostScript using a program such as dvips.
man -k printf
Search the short descriptions and manual page names for the keyword printf as regular expression.
Print out any matches. Equivalent to apropos printf.
man -f smail
Lookup the manual pages referenced by smail and print out the short descriptions of any found.
Equivalent to whatis smail.
OVERVIEW
Many options are available to man in order to give as much flexibility as possible to the user. Changes
can be made to the search path, section order, output processor, and other behaviours and operations
detailed below.
If set, various environment variables are interrogated to determine the operation of man. It is possible
to set the "catch-all" variable $MANOPT to any string in command line format, with the exception that any
spaces used as part of an option's argument must be escaped (preceded by a backslash). man will parse
$MANOPT prior to parsing its own command line. Those options requiring an argument will be overridden by
the same options found on the command line. To reset all of the options set in $MANOPT, -D can be
specified as the initial command line option. This will allow man to "forget" about the options
specified in $MANOPT, although they must still have been valid.
Manual pages are normally stored in nroff(1) format under a directory such as /usr/share/man. In some
installations, there may also be preformatted cat pages to improve performance. See manpath(5) for
details of where these files are stored.
This package supports manual pages in multiple languages, controlled by your locale. If your system did
not set this up for you automatically, then you may need to set $LC_MESSAGES, $LANG, or another system-
dependent environment variable to indicate your preferred locale, usually specified in the POSIX format:
<language>[_<territory>[.<character-set>[,<version>]]]
If the desired page is available in your locale, it will be displayed in lieu of the standard (usually
American English) page.
If you find that the translations supplied with this package are not available in your native language
and you would like to supply them, please contact the maintainer who will be coordinating such activity.
Individual manual pages are normally written and maintained by the maintainers of the program, function,
or other topic that they document, and are not included with this package. If you find that a manual
page is missing or inadequate, please report that to the maintainers of the package in question.
For information regarding other features and extensions available with this manual pager, please read the
documents supplied with the package.
DEFAULTS
The order of sections to search may be overridden by the environment variable $MANSECT or by the SECTION
directive in /etc/manpath.config. By default it is as follows:
1 n l 8 3 0 2 3type 3posix 3pm 3perl 3am 5 4 9 6 7
The formatted manual page is displayed using a pager. This can be specified in a number of ways, or else
will fall back to a default (see option -P for details).
The filters are deciphered by a number of means. Firstly, the command line option -p or the environment
variable $MANROFFSEQ is interrogated. If -p was not used and the environment variable was not set, the
initial line of the nroff file is parsed for a preprocessor string. To contain a valid preprocessor
string, the first line must resemble
'\" <string>
where string can be any combination of letters described by option -p below.
If none of the above methods provide any filter information, a default set is used.
A formatting pipeline is formed from the filters and the primary formatter (nroff or [tg]roff with -t)
and executed. Alternatively, if an executable program mandb_nfmt (or mandb_tfmt with -t) exists in the
man tree root, it is executed instead. It gets passed the manual source file, the preprocessor string,
and optionally the device specified with -T or -E as arguments.
OPTIONS
Non-argument options that are duplicated either on the command line, in $MANOPT, or both, are not
harmful. For options that require an argument, each duplication will override the previous argument
value.
General options
-C file, --config-file=file
Use this user configuration file rather than the default of ~/.manpath.
-d, --debug
Print debugging information.
-D, --default
This option is normally issued as the very first option and resets man's behaviour to its default.
Its use is to reset those options that may have been set in $MANOPT. Any options that follow -D
will have their usual effect.
--warnings[=warnings]
Enable warnings from groff. This may be used to perform sanity checks on the source text of
manual pages. warnings is a comma-separated list of warning names; if it is not supplied, the
default is "mac". To disable a groff warning, prefix it with "!": for example,
--warnings=mac,!break enables warnings in the "mac" category and disables warnings in the "break"
category. See the “Warnings” node in info groff for a list of available warning names.
Main modes of operation
-f, --whatis
Approximately equivalent to whatis. Display a short description from the manual page, if
available. See whatis(1) for details.
-k, --apropos
Approximately equivalent to apropos. Search the short manual page descriptions for keywords and
display any matches. See apropos(1) for details.
-K, --global-apropos
Search for text in all manual pages. This is a brute-force search, and is likely to take some
time; if you can, you should specify a section to reduce the number of pages that need to be
searched. Search terms may be simple strings (the default), or regular expressions if the --regex
option is used.
Note that this searches the sources of the manual pages, not the rendered text, and so may include
false positives due to things like comments in source files, or false negatives due to things like
hyphens being written as "\-" in source files. Searching the rendered text would be much slower.
-l, --local-file
Activate "local" mode. Format and display local manual files instead of searching through the
system's manual collection. Each manual page argument will be interpreted as an nroff source file
in the correct format. No cat file is produced. If '-' is listed as one of the arguments, input
will be taken from stdin.
If this option is not used, then man will also fall back to interpreting manual page arguments as
local file names if the argument contains a "/" character, since that is a good indication that
the argument refers to a path on the file system.
-w, --where, --path, --location
Don't actually display the manual page, but do print the location of the source nroff file that
would be formatted. If the -a option is also used, then print the locations of all source files
that match the search criteria.
-W, --where-cat, --location-cat
Don't actually display the manual page, but do print the location of the preformatted cat file
that would be displayed. If the -a option is also used, then print the locations of all
preformatted cat files that match the search criteria.
If -w and -W are both used, then print both source file and cat file separated by a space. If all
of -w, -W, and -a are used, then do this for each possible match.
-c, --catman
This option is not for general use and should only be used by the catman program.
-R encoding, --recode=encoding
Instead of formatting the manual page in the usual way, output its source converted to the
specified encoding. If you already know the encoding of the source file, you can also use
manconv(1) directly. However, this option allows you to convert several manual pages to a single
encoding without having to explicitly state the encoding of each, provided that they were already
installed in a structure similar to a manual page hierarchy.
Consider using man-recode(1) instead for converting multiple manual pages, since it has an
interface designed for bulk conversion and so can be much faster.
Finding manual pages
-L locale, --locale=locale
man 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
man. 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.
-m system[,...], --systems=system[,...]
If this system has access to other operating systems' manual pages, they can be accessed using
this option. To search for a manual page from NewOS's manual page collection, 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 manual pages, include the system name man in the argument
string. This option will override the $SYSTEM environment variable.
-M path, --manpath=path
Specify an alternate manpath to use. By default, man uses manpath derived code to determine the
path to search. This option overrides the $MANPATH environment variable and causes option -m to
be ignored.
A path specified as a manpath must be the root of a manual page hierarchy structured into sections
as described in the man-db manual (under "The manual page system"). To view manual pages outside
such hierarchies, see the -l option.
-S list, -s list, --sections=list
The given list is a colon- or comma-separated list of sections, used to determine which manual
sections to search and in what order. This option overrides the $MANSECT environment variable.
(The -s spelling is for compatibility with System V.)
-e sub-extension, --extension=sub-extension
Some systems incorporate large packages of manual pages, such as those that accompany the Tcl
package, into the main manual page hierarchy. To get around the problem of having two manual
pages with the same name such as exit(3), the Tcl pages were usually all assigned to section l.
As this is unfortunate, it is now possible to put the pages in the correct section, and to assign
a specific "extension" to them, in this case, exit(3tcl). Under normal operation, man will
display exit(3) in preference to exit(3tcl). To negotiate this situation and to avoid having to
know which section the page you require resides in, it is now possible to give man a sub-extension
string indicating which package the page must belong to. Using the above example, supplying the
option -e tcl to man will restrict the search to pages having an extension of *tcl.
-i, --ignore-case
Ignore case when searching for manual pages. This is the default.
-I, --match-case
Search for manual pages case-sensitively.
--regex
Show all pages with any part of either their names or their descriptions matching each page
argument as a regular expression, as with apropos(1). Since there is usually no reasonable way to
pick a "best" page when searching for a regular expression, this option implies -a.
--wildcard
Show all pages with any part of either their names or their descriptions matching each page
argument using shell-style wildcards, as with apropos(1) --wildcard. The page argument must match
the entire name or description, or match on word boundaries in the description. Since there is
usually no reasonable way to pick a "best" page when searching for a wildcard, this option implies
-a.
--names-only
If the --regex or --wildcard option is used, match only page names, not page descriptions, as with
whatis(1). Otherwise, no effect.
-a, --all
By default, man will exit after displaying the most suitable manual page it finds. Using this
option forces man to display all the manual pages with names that match the search criteria.
-u, --update
This option causes man to update its database caches of installed manual pages. This is only
needed in rare situations, and it is normally better to run mandb(8) instead.
--no-subpages
By default, man will try to interpret pairs of manual page names given on the command line as
equivalent to a single manual page name containing a hyphen or an underscore. This supports the
common pattern of programs that implement a number of subcommands, allowing them to provide manual
pages for each that can be accessed using similar syntax as would be used to invoke the
subcommands themselves. For example:
$ man -aw git diff
/usr/share/man/man1/git-diff.1.gz
To disable this behaviour, use the --no-subpages option.
$ man -aw --no-subpages git diff
/usr/share/man/man1/git.1.gz
/usr/share/man/man3/Git.3pm.gz
/usr/share/man/man1/diff.1.gz
Controlling formatted output
-P pager, --pager=pager
Specify which output pager to use. By default, man uses pager, falling back to cat if pager is
not found or is not executable. This option overrides the $MANPAGER environment variable, which
in turn overrides the $PAGER environment variable. It is not used in conjunction with -f or -k.
The value may be a simple command name or a command with arguments, and may use shell quoting
(backslashes, single quotes, or double quotes). It may not use pipes to connect multiple
commands; if you need that, use a wrapper script, which may take the file to display either as an
argument or on standard input.
-r prompt, --prompt=prompt
If a recent version of less is used as the pager, man will attempt to set its prompt and some
sensible options. The default prompt looks like
Manual page name(sec) line x
where name denotes the manual page name, sec denotes the section it was found under and x the
current line number. This is achieved by using the $LESS environment variable.
Supplying -r with a string will override this default. The string may contain the text $MAN_PN
which will be expanded to the name of the current manual page and its section name surrounded by
"(" and ")". The string used to produce the default could be expressed as
\ Manual\ page\ \$MAN_PN\ ?ltline\ %lt?L/%L.:
byte\ %bB?s/%s..?\ (END):?pB\ %pB\\%..
(press h for help or q to quit)
It is broken into three lines here for the sake of readability only. For its meaning see the
less(1) manual page. The prompt string is first evaluated by the shell. All double quotes, back-
quotes and backslashes in the prompt must be escaped by a preceding backslash. The prompt string
may end in an escaped $ which may be followed by further options for less. By default man sets
the -ix8 options.
The $MANLESS environment variable described below may be used to set a default prompt string if
none is supplied on the command line.
-7, --ascii
When viewing a pure ascii(7) manual page on a 7 bit terminal or terminal emulator, some characters
may not display correctly when using the latin1(7) device description with GNU nroff. This option
allows pure ascii manual pages to be displayed in ascii with the latin1 device. It will not
translate any latin1 text. The following table shows the translations performed: some parts of it
may only be displayed properly when using GNU nroff's latin1(7) device.
Description Octal latin1 ascii
─────────────────────────────────────────────
continuation hyphen 255 ‐ -
bullet (middle dot) 267 • o
acute accent 264 ´ '
multiplication sign 327 × x
If the latin1 column displays correctly, your terminal may be set up for latin1 characters and
this option is not necessary. If the latin1 and ascii columns are identical, you are reading this
page using this option or man did not format this page using the latin1 device description. If
the latin1 column is missing or corrupt, you may need to view manual pages with this option.
This option is ignored when using options -t, -H, -T, or -Z and may be useless for nroff other
than GNU's.
-E encoding, --encoding=encoding
Generate output for a character encoding other than the default. For backward compatibility,
encoding may be an nroff device such as ascii, latin1, or utf8 as well as a true character
encoding such as UTF-8.
--no-hyphenation, --nh
Normally, nroff will automatically hyphenate text at line breaks even in words that do not contain
hyphens, if it is necessary to do so to lay out words on a line without excessive spacing. This
option disables automatic hyphenation, so words will only be hyphenated if they already contain
hyphens.
If you are writing a manual page and simply want to prevent nroff from hyphenating a word at an
inappropriate point, do not use this option, but consult the nroff documentation instead; for
instance, you can put "\%" inside a word to indicate that it may be hyphenated at that point, or
put "\%" at the start of a word to prevent it from being hyphenated.
--no-justification, --nj
Normally, nroff will automatically justify text to both margins. This option disables full
justification, leaving justified only to the left margin, sometimes called "ragged-right" text.
If you are writing a manual page and simply want to prevent nroff from justifying certain
paragraphs, do not use this option, but consult the nroff documentation instead; for instance, you
can use the ".na", ".nf", ".fi", and ".ad" requests to temporarily disable adjusting and filling.
-p string, --preprocessor=string
Specify the sequence of preprocessors to run before nroff or troff/groff. Not all installations
will have a full set of preprocessors. Some of the preprocessors and the letters used to
designate them are: eqn (e), grap (g), pic (p), tbl (t), vgrind (v), refer (r). This option
overrides the $MANROFFSEQ environment variable. zsoelim is always run as the very first
preprocessor.
-t, --troff
Use groff -mandoc to format the manual page to stdout. This option is not required in conjunction
with -H, -T, or -Z.
-T[device], --troff-device[=device]
This option is used to change groff (or possibly troff's) output to be suitable for a device other
than the default. It implies -t. Examples (as of groff 1.23.0) include dvi, latin1, pdf, ps,
utf8, X75 and X100.
-H[browser], --html[=browser]
This option will cause groff to produce HTML output, and will display that output in a web
browser. The choice of browser is determined by the optional browser argument if one is provided,
by the $BROWSER environment variable, or by a compile-time default if that is unset (usually
lynx). This option implies -t, and will only work with GNU troff.
-X[dpi], --gxditview[=dpi]
This option displays the output of groff in a graphical window using the gxditview program. The
dpi (dots per inch) may be 75, 75-12, 100, or 100-12, defaulting to 75; the -12 variants use a
12-point base font. This option implies -T with the X75, X75-12, X100, or X100-12 device
respectively.
-Z, --ditroff
groff will run troff and then use an appropriate post-processor to produce output suitable for the
chosen device. If groff -mandoc is groff, this option is passed to groff and will suppress the
use of a post-processor. It implies -t.
Getting help
-?, --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.
3 A child process returned a non-zero exit status.
16 At least one of the pages/files/keywords didn't exist or wasn't matched.
ENVIRONMENT
MANPATH
If $MANPATH is set, its value is used as the path to search for manual pages.
See the SEARCH PATH section of manpath(5) for the default behaviour and details of how this
environment variable is handled.
MANROFFOPT
Every time man invokes the formatter (nroff, troff, or groff), it adds the contents of $MANROFFOPT
to the formatter's command line.
For example, MANROFFOPT=-P-i tells the formatter to use italic text (which is only supported by
some terminals) rather than underlined text.
MANROFFSEQ
If $MANROFFSEQ is set, its value is used to determine the set of preprocessors to pass each manual
page through. The default preprocessor list is system dependent.
MANSECT
If $MANSECT is set, its value is a colon-delimited list of sections and it is used to determine
which manual sections to search and in what order. The default is "1 n l 8 3 0 2 3type 3posix 3pm
3perl 3am 5 4 9 6 7", unless overridden by the SECTION directive in /etc/manpath.config.
MANPAGER, PAGER
If $MANPAGER or $PAGER is set ($MANPAGER is used in preference), its value is used as the name of
the program used to display the manual page. By default, pager is used, falling back to cat if
pager is not found or is not executable.
The value may be a simple command name or a command with arguments, and may use shell quoting
(backslashes, single quotes, or double quotes). It may not use pipes to connect multiple
commands; if you need that, use a wrapper script, which may take the file to display either as an
argument or on standard input.
MANLESS
If $MANLESS is set, its value will be used as the default prompt string for the less pager, as if
it had been passed using the -r option (so any occurrences of the text $MAN_PN will be expanded in
the same way). For example, if you want to set the prompt string unconditionally to “my prompt
string”, set $MANLESS to ‘-Psmy prompt string’. Using the -r option overrides this environment
variable.
BROWSER
If $BROWSER is set, its value is a colon-delimited list of commands, each of which in turn is used
to try to start a web browser for man --html. In each command, %s is replaced by a filename
containing the HTML output from groff, %% is replaced by a single percent sign (%), and %c is
replaced by a colon (:).
SYSTEM If $SYSTEM is set, it will have the same effect as if it had been specified as the argument to the
-m option.
MANOPT If $MANOPT is set, it will be parsed prior to man's command line and is expected to be in a
similar format. As all of the other man specific environment variables can be expressed as
command line options, and are thus candidates for being included in $MANOPT it is expected that
they will become obsolete. N.B. All spaces that should be interpreted as part of an option's
argument must be escaped.
MANWIDTH
If $MANWIDTH is set, its value is used as the line length for which manual pages should be
formatted. If it is not set, manual pages will be formatted with a line length appropriate to the
current terminal (using the value of $COLUMNS, and ioctl(2) if available, or falling back to 80
characters if neither is available). Cat pages will only be saved when the default formatting can
be used, that is when the terminal line length is between 66 and 80 characters.
MAN_KEEP_FORMATTING
Normally, when output is not being directed to a terminal (such as to a file or a pipe),
formatting characters are discarded to make it easier to read the result without special tools.
However, if $MAN_KEEP_FORMATTING is set to any non-empty value, these formatting characters are
retained. This may be useful for wrappers around man that can interpret formatting characters.
MAN_KEEP_STDERR
Normally, when output is being directed to a terminal (usually to a pager), any error output from
the command used to produce formatted versions of manual pages is discarded to avoid interfering
with the pager's display. Programs such as groff often produce relatively minor error messages
about typographical problems such as poor alignment, which are unsightly and generally confusing
when displayed along with the manual page. However, some users want to see them anyway, so, if
$MAN_KEEP_STDERR is set to any non-empty value, error output will be displayed as usual.
MAN_DISABLE_SECCOMP
On Linux, man normally confines subprocesses that handle untrusted data using a seccomp(2)
sandbox. This makes it safer to run complex parsing code over arbitrary manual pages. If this
goes wrong for some reason unrelated to the content of the page being displayed, you can set
$MAN_DISABLE_SECCOMP to any non-empty value to disable the sandbox.
PIPELINE_DEBUG
If the $PIPELINE_DEBUG environment variable is set to "1", then man will print debugging messages
to standard error describing each subprocess it runs.
LANG, LC_MESSAGES
Depending on system and implementation, either or both of $LANG and $LC_MESSAGES will be
interrogated for the current message locale. man will display its messages in that locale (if
available). See setlocale(3) for precise details.
FILES
/etc/manpath.config
man-db configuration file.
/usr/share/man
A global manual page hierarchy.
STANDARDS
POSIX.1-2001, POSIX.1-2008, POSIX.1-2017.
SEE ALSO
apropos(1), groff(1), less(1), manpath(1), nroff(1), troff(1), whatis(1), zsoelim(1), manpath(5), man(7),
catman(8), mandb(8)
Documentation for some packages may be available in other formats, such as info(1) or HTML.
HISTORY
1990, 1991 – Originally written by John W. Eaton (jwe@che.utexas.edu).
Dec 23 1992: Rik Faith (faith@cs.unc.edu) applied bug fixes supplied by Willem Kasdorp
(wkasdo@nikhefk.nikef.nl).
30th April 1994 – 23rd February 2000: Wilf. (G.Wilford@ee.surrey.ac.uk) has been developing and
maintaining this package with the help of a few dedicated people.
30th October 1996 – 30th March 2001: Fabrizio Polacco <fpolacco@debian.org> maintained and enhanced this
package for the Debian project, with the help of all the community.
31st March 2001 – present day: Colin Watson <cjwatson@debian.org> is now developing and maintaining man-
db.
BUGS
https://gitlab.com/man-db/man-db/-/issues
https://savannah.nongnu.org/bugs/?group=man-db