man - an interface to the on-line reference manuals
[-adhu7V] [-m system[,...]] [-L
locale] [-p string] [-M
path] [-P pager] [-r
prompt] [-S list] [-e
page ...] ...
man -l [-7] [-tZT device] [-p string] [-P pager] [-r prompt] file ...
man -k [-M path] keyword ...
man -f [-M path] page ...
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 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.
A manual page consists of several parts.
They may be labelled NAME, SYNOPSIS, DESCRIPTION, OPTIONS, FILES, SEE ALSO, BUGS, and AUTHOR.
The following conventions apply to the SYNOPSIS section and can be used as a guide in other sections.
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.
Display the manual page for the item (program) ls.
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 alias | lpr -Pps
Format the manual page referenced by ’alias’, usually a shell manual page, 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. Print out any matches.
man -f smail
Lookup the manual pages referenced by smail and print out the short descriptions of any found.
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 it’s 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.
The manual pager utilities packaged as man_db make extensive use of index database caches. These caches contain information such as where each manual page can be found on the filesystem and what its whatis (short one line description of the man page) contains. One of man’s jobs is to ensure that the caches remain consistent. These database caches obviate the need for having to manually run software to update traditional whatis text databases, and also allow man to run faster than if it had to search the filesystem each time to find the appropriate manual page.
If man cannot find a mandb initiated index database for a particular manual page hierarchy, it will still search for the requested manual pages although file globbing will be necessary to search within that hierarchy. If whatis or apropos fails to find an index it will try to extract information from a traditional whatis database instead.
These utilities support compressed source nroff files having, by default, the extensions of .Z, .z and .gz. It is possible to deal with any compression extension, but this information must be known at compile time. Also, by default, any cat pages produced are compressed using gzip. Each ’global’ manual page hierarchy such as /usr/man or /usr/X11R6/man may have any directory as its cat page hierarchy. Traditionally the cat pages are stored under the same hierarchy as the man pages, but for reasons such as those specified in the Linux File System Standard (FSSTND), it may be better to store them elsewhere. For details on how to do this, please read manpath(5). For details on why to do this, read the standard.
International support is available with this package. Native language manual pages are accessible (if available on your system) via use of locale functions. To activate such support, it is necessary to set either $LC_MESSAGES, $LANG or another system dependent environment variable to your language locale, usually specified in the POSIX 1003.1 based format:
If the desired page is available in your locale, it will be displayed in lieu of the standard (usually American English) page.
Support for international message catalogues is also featured in this package and can be activated in the same way, again if available. If you find that the manual pages and message catalogues supplied with this package are not available in your native language and you would like to supply them, please contact the author who will be coordinating such activity.
For information regarding other features and extensions available with this manual pager, please read the documents supplied with the package.
man will search for the desired manual pages within the index database caches. If the ’lookup’ is unsuccessful, a cache consistency check is performed to ensure the databases accurately reflect the filesystem. It is not generally necessary to run mandb after the caches are initially created, unless a cache becomes corrupt.
Once a manual page has been located, a check is performed to find out if a relative preformatted ’cat’ file already exists and is newer than the nroff file. If it does and is, this preformatted file is (usually) decompressed and then displayed, via use of a pager. The pager can be specified in a number of ways or the default is used (see option -P for details). If no cat is found or is older than the nroff file, the nroff is filtered through various programs and is shown immediately.
If a cat file can be produced (a relative cat directory exists and has appropriate permissions), man will compress and store the cat file in the background.
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
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 as arguments.
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.
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.
-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.
This option is normally issued as the very first option and resets man’s behaviour to it’s default. It’s use is to reset those options that may have been set in $MANOPT. Any options that follow -D will have their usual effect.
-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.
-P pager, --pager=pager
Specify which output pager to use. By default, man uses less -s. This option overrides the $PAGER environment variable and is not used in conjunction with -f or -k.
-r prompt, --prompt=prompt
If a recent version of less is used as the pager, man will attempt to set it’s 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 it’s section name encompassed 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\\%..
It is broken into two lines here for the sake of readability only. For it’s 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.
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.
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, -T or -Z and may be useless for nroff other than GNU’s.
-S list, --sections=list
List is a colon separated list of ’order specific’ manual sections to search. This option overrides the $MANSECT environment variable.
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.
This option is not for general use and should only be used by the catman program.
Don’t actually display any manual pages, but do print lots of debugging information.
-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 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.
Equivalent to whatis. Display a short description from the manual page, if available. See whatis(1) for details.
Print a help message and exit.
Equivalent to apropos. Search the short manual page descriptions for keywords and display any matches. See apropos(1) for details.
-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.
-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.
The index database caches are updated ’on the fly’, that is, they do not require mandb to be run periodically to be kept consistent. If your chosen manual page is not located within the cache or the -a option is used, man will do a ’directory level’ consistency check to ensure that it’s caches are an accurate representation of the filesystem. To force an ’inode level’ consistency check prior to finding any manual pages, use option -u.
Use /usr/bin/groff -mandoc to format the manual page to stdout. This option is not required in conjunction with either -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-1.09) include dvi, latin1, X75 and X100.
groff will run troff and then use an appropriate post-processor to produce output suitable for the chosen device. If /usr/bin/groff -mandoc is groff, this option is passed to groff and will suppress the use of a post-processor. It implies -t.
-w, --where, --location
Don’t actually display the manual pages, but do print the location(s) of the files that would be formatted or displayed. If the file is a cat file, also show the location of its source nroff file.
Display version and author information.
Successful program execution.
Usage, syntax or configuration file error.
A child process returned a non-zero exit status.
At least one of the pages/files/keywords didn’t exist or wasn’t matched.
If $MANPATH is set, its value is used as the path to search for manual pages.
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.
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.
If $PAGER is set, its value is used as the name of the program used to display the manual page. By default, less -s is used.
If $SYSTEM is set, it will have the same effect as option -m string where string will be taken as $SYSTEM’s contents.
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.
Depending on system and implementation, either or both of $LANG and $LC_MESSAGES will be interrogated for the current message locale. man will display it’s messages in that locale (if available). See setlocale(3) for precise details.
man_db configuration file.
A global manual page hierarchy.
A traditional global index database cache.
An alternate or FSSTND compliant global index database cache.
Example of an optional per-hierarchy nroff based formatter script.
Example of an optional per-hierarchy [tg]roff based formatter script used with -t.
mandb(8), manpath(1), manpath(5), apropos(1), whatis(1), catman(8), less(1), nroff(1), troff(1), groff(1), zsoelim(1), setlocale(3), ascii(7), latin1(7), FSSTND.
1990, 1991 - Originally written by John W. Eaton (firstname.lastname@example.org).
Dec 23 1992: Rik Faith (email@example.com) applied bug fixes supplied by Willem Kasdorp (firstname.lastname@example.org).
April 30th, 1994 - July 12th, 1995: Wilf. (G.Wilford@ee.surrey.ac.uk) has been developing and maintaining this package with the help of a few dedicated people.