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 system libraries)
4
Special files (usually found in /dev)
5
File formats and conventions eg /etc/passwd
6
Games
7
Macro packages and conventions eg 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 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 -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
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, 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.
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 compile 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 Hierarchy 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:
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 coordinating 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 performed 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 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
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.
-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 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.
-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.
-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.
-P pager, --pager=pager
Specify which output pager to use.
By default,
man
uses
exec /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 surrounded by `(' and `)'.
The string used to produce the default could be expressed as
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.
-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
GNUnroff.
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.
Description
Octal
latin1
ascii
continuation hyphen
255
[char173]
-
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 sections 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
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.
-f, --whatis
Equivalent to
whatis.
Display a short description from the manual page, if available. See
whatis(1)
for details.
-h, --help
Print a help message and exit.
-k, --apropos
Equivalent to
apropos.
Search the short manual page descriptions for keywords and display any
matches.
See
apropos(1)
for details.
-msystem[,...],--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
-mNewOS.
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.
-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-1.09) include
dvi, latin1,
X75 and X100.
-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, --html
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
$BROWSER
environment variable, or by a compile-time default if that is unset (usually
lynx).
This option implies
-t,
and will only work with
GNUtroff.
-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.
-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.
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.
PAGER
If
$PAGER
is set, its value is used as the name of the program used to display
the manual page.
By default,
exec /usr/bin/pager -s
is used.
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 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 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 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 formatting 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 available).
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.
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 - 07 September 2001: Colin Watson <cjwatson@debian.org> is now
developing and maintaining man-db.