man

MAN(1)                         Manual pager utils                         MAN(1)



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)
       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, CONFORMING TO, 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/man_db.conf.  By
       default it is as follows:

              1 1p n l 8 3 3p 0 0p 2 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".  See the “Warnings” node in info groff for a
              list of available warning names.

   Main modes of operation
       -f, --whatis
              Equivalent to whatis.  Display a short description from the manual
              page, if available.  See whatis(1) for details.

       -k, --apropos
              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.  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.  When
              this option is not used, and man fails to find the page required,
              before displaying the error message, it attempts to act as if this
              option was supplied, using the name as a filename and looking for
              an exact match.

       -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 system's 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 less,
              falling back to cat if less 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      255      ‐        -
              hyphen
              bullet (middle    267      •        o
              dot)
              acute accent      264      ´        '
              multiplication    327      ×        x
              sign

              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 (provided with Groff-1.17) include dvi, latin1, 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.

       MANROFFOPT
              Every time man invokes the formatter (nroff, troff, or groff), it
              adds the contents of $MANROFFOPT to the formatter's command line.

       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 1p n l 8 3 3p 0 0p 2
              5 4 9 6 7", unless overridden by the SECTION directive in
              /etc/man_db.conf.

       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, less is used, falling back to cat if
              less 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.

       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/man_db.conf
              man-db configuration file.

       /usr/share/man
              A global manual page hierarchy.

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://savannah.nongnu.org/bugs/?group=man-db



2.9.4                              2021-02-08                             MAN(1)