Provided by:
man-db_2.4.4-3_i386 
NAME
man - an interface to the on-line reference manuals
SYNOPSIS
man [-c|-w|-tZ] [-H[browser]] [-T[device]] [-X[dpi]] [-adhu7V] [-i|-I]
[-m system[,...]] [-L locale] [-p string] [-C file] [-M path] [-P
pager] [-r prompt] [-S list] [-e extension] [[section] page ...] ...
man -l [-7] [-tZ] [-H[browser]] [-T[device]] [-X[dpi]] [-p string] [-P
pager] [-r prompt] file ...
man -k [apropos options] regexp ...
man -f [whatis 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 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 eg /etc/passwd
6 Games
7 Miscellaneous (including macro packages and conven‐
tions), 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 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.
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.
The command or function illustration is a pattern that should match all
possible invocations. In some cases it is advisable to illustrate sev‐
eral 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 -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 man‐
ual 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 redi‐
rection 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 -r printf.
man -f smail
Lookup the manual pages referenced by smail and print out the short
descriptions of any found. Equivalent to whatis -r 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, sec‐
tion 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 (pre‐
ceded 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.
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, and allow man to
run faster than if it had to search the filesystem each time to find
the appropriate manual page. If requested using the -u option, man
will ensure that the caches remain consistent, which can obviate the
need to manually run software to update traditional whatis text
databases.
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 com‐
pile time. Also, by default, any cat pages produced are compressed
using gzip. Each ‘global’ manual page hierarchy such as /usr/share/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 File Hierar
chy Standard (FHS), 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:
<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.
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 maintainer who will be coordi‐
nating such activity.
For information regarding other features and extensions available with
this manual pager, please read the documents supplied with the package.
DEFAULTS
man will search for the desired manual pages within the index database
caches. If the -u option is given, a cache consistency check is per‐
formed to ensure the databases accurately reflect the filesystem. If
this option is always given, it is not generally necessary to run mandb
after the caches are initially created, unless a cache becomes corrupt.
However, the cache consistency check can be slow on systems with many
manual pages installed, so it is not performed by default, and system
administrators may wish to run mandb every week or so to keep the
database caches fresh. To forestall problems caused by outdated
caches, man will fall back to file globbing if a cache lookup fails,
just as it would if no cache was present.
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 else will fall back to a 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 ini‐
tial 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 for‐
matter (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 argu‐
ment, each duplication will override the previous argument value.
-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.
-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 tem‐
porarily override the determined value, use this option to sup‐
ply 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.
-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.
-C file, --config-file=file
Use this user configuration file rather than the default of
~/.manpath.
-M path, --manpath=path
Specify an alternate manpath to use. By default, man uses man
path 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.
-P pager, --pager=pager
Specify which output pager to use. By default, man uses
/usr/bin/pager -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 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 sur‐
rounded 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 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.
If you want to override man’s prompt string processing com‐
pletely, use the $MANLESS environment variable described below.
-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.
-S list, --sections=list
List is a colon-separated list of ‘order specific’ manual sec‐
tions to search. This option overrides the $MANSECT environment
variable.
-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.
-c, --catman
This option is not for general use and should only be used by
the catman program.
-d, --debug
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 sub-extension string indicating which
package the page must belong to. Using the above example, sup‐
plying the option -e tcl to man will restrict the search to
pages having an extension of *tcl.
-f, --whatis
Equivalent to whatis. Display a short description from the man‐
ual page, if available. See whatis(1) for details.
-h, --help
Print a help message and exit.
-i, --ignore-case
Ignore case when searching for manual pages. This is the
default.
-I, --match-case
Search for manual pages case-sensitively.
-k, --apropos
Equivalent to apropos. Search the short manual page descrip‐
tions 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 oper‐
ating system’s manual pages, include the system name man in the
argument string. This option will override the $SYSTEM environ‐
ment 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 pre‐
processors. 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 environ‐
ment variable. zsoelim is always run as the very first prepro‐
cessor.
-u, --update
This option causes man to perform an ‘inode level’ consistency
check on its database caches to ensure that they are an accurate
representation of the filesystem. It will only have a useful
effect if man is installed with the setuid bit set.
-t, --troff
Use /usr/bin/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.
-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
/usr/bin/groff -mandoc is groff, this option is passed to groff
and will suppress the use of a post-processor. It implies -t.
-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.
-E device, --encoding=device
Generate output for a character encoding other than the default.
Due to the way nroff is currently designed, the argument to this
function must be an nroff device such as ascii, latin1, or utf8.
-w, --where, --location
Don’t actually display the manual pages, but do print the loca‐
tion(s) of the source nroff files that would be formatted.
-W, --where-cat, --location-cat
Don’t actually display the manual pages, but do print the loca‐
tion(s) of the cat files that would be displayed. If -w and -W
are both specified, print both separated by a space.
-V, --version
Display version information.
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.
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 sec‐
tions and it is used to determine which manual sections to
search and in what order.
PAGER If $PAGER is set, its value is used as the name of the program
used to display the manual page. By default, /usr/bin/pager -s
is used.
MANLESS
If $MANLESS is set, man will not perform any of its usual pro‐
cessing to set up a prompt string for the less pager. Instead,
the value of $MANLESS will be copied verbatim into $LESS. For
example, if you want to set the prompt string unconditionally to
“my prompt string”, set $MANLESS to ‘-Psmy prompt string’.
BROWSER
If $BROWSER is set, its value is a colon-delimited list of com‐
mands, 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 option -m
string where string will be taken as $SYSTEM’s contents.
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 argu‐
ment 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, man‐
ual pages will be formatted with a line length appropriate to
the current terminal (using an ioctl(2) if available, the value
of $COLUMNS, or falling back to 80 characters if neither is
available). Cat pages will only be saved when the default for‐
matting can be used, that is when the terminal line length is
between 66 and 80 characters.
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 avail‐
able). See setlocale(3) for precise details.
FILES
/etc/manpath.config
man-db configuration file.
/usr/share/man
A global manual page hierarchy.
/usr/share/man/index.(bt|db|dir|pag)
A traditional global index database cache.
/var/cache/man/index.(bt|db|dir|pag)
An alternate or FHS compliant global index database cache.
mandb(8), manpath(1), manpath(5), apropos(1), whatis(1), catman(8),
less(1), nroff(1), troff(1), groff(1), zsoelim(1), setlocale(3),
man(7), ascii(7), latin1(7), the man-db package manual, FSSTND.
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 <fpo‐
lacco@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.