man [OPTION...] [[SECTION] PAGE ...] ...
!subtitle:功能
查看系统手册。
!subtitle:类型
Bash 内置命令。
man也是 coreutils 的一个可执行文件；为了保持 POSIX 标准的兼容性，确保在其他 shell（比如一些极简的或古老的 shell）或者某些特定环境下，命令依然可用。
!subtitle:参数
OPTION 选项：
-C file, --config-file=file - 使用用户配置的文件，而不是默认的 ~/.manpath
-d, --debug - 打印调试信息
-D, --default - 将命令的行为重置为默认值，通常用作第一个选项
--warnings[=warnings] - 开启 groff 警告
SECTION 章节：
可执行程序和 SHELL 命令
系统调用（内核提高的函数）
库函数
特殊文件
文件格式约定（例如 /etc/passwd）
游戏
杂项
系统管理员命令
内核例程（非标准）
PAGE 页面 - 具体要查看的文档，可以是命令名、函数名等。
MANPATH - 指定 man 文档的搜索路径
MANROFFOPT - man 格式化时，内容添加到格式化命令行中
MANROFFSEQ - 指定预处理器
MANSECT - 指定章节的搜索顺序，以冒号分隔的章节列表
MANPAGER, PAGER - 用作手册页显示的程序名
MANLESS - 用作 less 分页器的提示字符串
BROWSER - man --html 时尝试启动的 Web 浏览器列表，以冒号分隔
SYSTEM - 要查看的系统（可以查看其它系统的手册）
MANWIDTH - 输出的宽度
MAN_KEEP_FORMATTING - 输出到非终端设备时（例如文件），保持格式化
MAN_KEEP_STDERR - 输出到非终端设备时（例如文件），保留错误
MAN_DISABLE_SECCOMP - 禁用安全沙盒；设为任何非空值
PIPELINE_DEBUG - 在标准错误中打印调试信息；设为 1
LANG, LC_MESSAGES - 语言
$ man chmod # 查看 chmod 的文档，默认查看第一个有效的章节
CHMOD(1) User Commands CHMOD(1)
NAME
chmod - change file mode bits
SYNOPSIS
chmod [OPTION]... MODE[,MODE]... FILE...
chmod [OPTION]... OCTAL-MODE FILE...
chmod [OPTION]... --reference=RFILE FILE...
...
$ man 2 chmod # 查看 第 2 章节（系统调用）的 chmod 的文档
chmod(2) System Calls Manual chmod(2)
NAME
chmod, fchmod, fchmodat - change permissions of a file
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <sys/stat.h>
int chmod(const char *pathname, mode_t mode);
int fchmod(int fd, mode_t mode);
#include <fcntl.h> /* Definition of AT_* constants */
#include <sys/stat.h>
int fchmodat(int dirfd, const char *pathname, mode_t mode, int flags);
...
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), man-pages(7)
8 System administration commands (usually only for root)
9 Kernel routines [Non standard]
A manual page consists of several sections.
Conventional section names include NAME, SYNOPSIS, CONFIGURATION, DE‐
SCRIPTION, OPTIONS, EXIT STATUS, RETURN VALUE, ERRORS, ENVIRONMENT,
FILES, VERSIONS, STANDARDS, NOTES, BUGS, EXAMPLE, AUTHORS, and
SEE ALSO.
The following conventions apply to the SYNOPSIS section and can be used
as a guide in other sections.
bold text type exactly as shown.
italic text replace with appropriate argument.
[-abc] any or all arguments within [ ] are optional.
-a|-b options delimited by | cannot be used together.
argument ... argument is repeatable.
[expression] ... entire expression within [ ] is repeatable.
Exact rendering may vary depending on the output device. For instance,
man will usually not be able to render italics when running in a termi‐
nal, 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 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 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 pro‐
tect 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 suc‐
cessive 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 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 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, sec‐
tion order, output processor, and other behaviours and operations de‐
tailed 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 op‐
tions 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 pre‐
formatted 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-depen‐
dent 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 docu‐
ment, and are not included with this package. If you find that a man‐
ual page is missing or inadequate, please report that to the maintain‐
ers of the package in question.
For information regarding other features and extensions available with
this manual pager, please read the documents supplied with the package.
DEFAULTS
The order of sections to search may be overridden by the environment
variable $MANSECT or by the SECTION directive in /etc/manpath.config.
By default it is as follows:
1 n l 8 3 0 2 3type 3posix 3pm 3perl 3am 5 4 9 6 7
The formatted manual page is displayed using a pager. This can be
specified in a number of ways, or else will fall back to a default (see
option -P for details).
The filters are deciphered by a number of means. Firstly, the command
line option -p or the environment variable $MANROFFSEQ is interrogated.
If -p was not used and the environment variable was not set, the 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.
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 re‐
sets 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 de‐
fault is "mac". To disable a groff warning, prefix it with "!":
for example, --warnings=mac,!break enables warnings in the "mac"
category and disables warnings in the "break" category. See the
“Warnings” node in info groff for a list of available warning
names.
Main modes of operation
-f, --whatis
Approximately equivalent to whatis. Display a short description
from the manual page, if available. See whatis(1) for details.
-k, --apropos
Approximately equivalent to apropos. Search the short manual
page descriptions for keywords and display any matches. See
apropos(1) for details.
-K, --global-apropos
Search for text in all manual pages. This is a brute-force
search, and is likely to take some time; if you can, you should
specify a section to reduce the number of pages that need to be
searched. Search terms may be simple strings (the default), or
regular expressions if the --regex option is used.
Note that this searches the sources of the manual pages, not the
rendered text, and so may include false positives due to things
like comments in source files, or false negatives due to things
like hyphens being written as "\-" in source files. Searching
the rendered text would be much slower.
-l, --local-file
Activate "local" mode. Format and display local manual files
instead of searching through the system's manual collection.
Each manual page argument will be interpreted as an nroff source
file in the correct format. No cat file is produced. If '-' is
listed as one of the arguments, input will be taken from stdin.
If this option is not used, then man will also fall back to in‐
terpreting manual page arguments as local file names if the ar‐
gument contains a "/" character, since that is a good indication
that the argument refers to a path on the file system.
-w, --where, --path, --location
Don't actually display the manual page, but do print the loca‐
tion 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 loca‐
tion of the preformatted cat file that would be displayed. If
the -a option is also used, then print the locations of all pre‐
formatted 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 man‐
conv(1) directly. However, this option allows you to convert
several manual pages to a single encoding without having to ex‐
plicitly state the encoding of each, provided that they were al‐
ready installed in a structure similar to a manual page hierar‐
chy.
Consider using man-recode(1) instead for converting multiple
manual pages, since it has an interface designed for bulk con‐
version 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 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.
-m system[,...], --systems=system[,...]
If this system has access to other operating systems' manual
pages, they can be accessed using this option. To search for a
manual page from NewOS's manual page collection, use the option
-m NewOS.
The system specified can be a combination of comma delimited op‐
erating system names. To include a search of the native operat‐
ing system's manual pages, include the system name man in the
argument string. This option will override the $SYSTEM environ‐
ment variable.
-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.
-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, sup‐
plying 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 de‐
fault.
-I, --match-case
Search for manual pages case-sensitively.
--regex
Show all pages with any part of either their names or their de‐
scriptions 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 de‐
scriptions matching each page argument using shell-style wild‐
cards, as with apropos(1) --wildcard. The page argument must
match the entire name or description, or match on word bound‐
aries 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 in‐
stalled 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 subcom‐
mands, allowing them to provide manual pages for each that can
be accessed using similar syntax as would be used to invoke the
subcommands themselves. For example:
$ man -aw git diff
/usr/share/man/man1/git-diff.1.gz
To disable this behaviour, use the --no-subpages option.
$ man -aw --no-subpages git diff
/usr/share/man/man1/git.1.gz
/usr/share/man/man3/Git.3pm.gz
/usr/share/man/man1/diff.1.gz
Controlling formatted output
-P pager, --pager=pager
Specify which output pager to use. By default, man uses pager,
falling back to cat if pager is not found or is not executable.
This option overrides the $MANPAGER environment variable, which
in turn overrides the $PAGER environment variable. It is not
used in conjunction with -f or -k.
The value may be a simple command name or a command with argu‐
ments, and may use shell quoting (backslashes, single quotes, or
double quotes). It may not use pipes to connect multiple com‐
mands; 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 at‐
tempt 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\\%..
(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 hy‐ 255 ‐ -
phen
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 us‐
ing 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 op‐
tion, but consult the nroff documentation instead; for instance,
you can use the ".na", ".nf", ".fi", and ".ad" requests to tem‐
porarily 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 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 pre‐
processor.
-t, --troff
Use groff -mandoc to format the manual page to stdout. This op‐
tion 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 de‐
fault 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 sup‐
press the use of a post-processor. It implies -t.
Getting help
-?, --help
Print a help message and exit.
--usage
Print a short usage message and exit.
-V, --version
Display version information.
EXIT STATUS
0 Successful program execution.
1 Usage, syntax or configuration file error.
2 Operational error.
3 A child process returned a non-zero exit status.
16 At least one of the pages/files/keywords didn't exist or wasn't
matched.
ENVIRONMENT
MANPATH
If $MANPATH is set, its value is used as the path to search for
manual pages.
See the SEARCH PATH section of manpath(5) for the default behav‐
iour and details of how this environment variable is handled.
MANROFFOPT
Every time man invokes the formatter (nroff, troff, or groff),
it adds the contents of $MANROFFOPT to the formatter's command
line.
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. The default is "1 n l 8 3 0 2 3type
3posix 3pm 3perl 3am 5 4 9 6 7", unless overridden by the SEC‐
TION directive in /etc/manpath.config.
MANPAGER, PAGER
If $MANPAGER or $PAGER is set ($MANPAGER is used in preference),
its value is used as the name of the program used to display the
manual page. By default, pager is used, falling back to cat if
pager is not found or is not executable.
The value may be a simple command name or a command with argu‐
ments, and may use shell quoting (backslashes, single quotes, or
double quotes). It may not use pipes to connect multiple com‐
mands; 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 envi‐
ronment variable.
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 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 ar‐
gument 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 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 for‐
matting 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. How‐
ever, 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 charac‐
ters.
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 inter‐
fering 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 gener‐
ally confusing when displayed along with the manual page. How‐
ever, some users want to see them anyway, so, if
$MAN_KEEP_STDERR is set to any non-empty value, error output
will be displayed as usual.
MAN_DISABLE_SECCOMP
On Linux, man normally confines subprocesses that handle un‐
trusted data using a seccomp(2) sandbox. This makes it safer to
run complex parsing code over arbitrary manual pages. If this
goes wrong for some reason unrelated to the content of the page
being displayed, you can set $MAN_DISABLE_SECCOMP to any non-
empty value to disable the sandbox.
PIPELINE_DEBUG
If the $PIPELINE_DEBUG environment variable is set to "1", then
man will print debugging messages to standard error describing
each subprocess it runs.
LANG, LC_MESSAGES
Depending on system and implementation, either or both of $LANG
and $LC_MESSAGES will be interrogated for the current message
locale. man will display its messages in that locale (if avail‐
able). See setlocale(3) for precise details.
FILES
/etc/manpath.config
man-db configuration file.
/usr/share/man
A global manual page hierarchy.
STANDARDS
POSIX.1-2001, POSIX.1-2008, POSIX.1-2017.
SEE ALSO
apropos(1), groff(1), less(1), manpath(1), nroff(1), troff(1),
whatis(1), zsoelim(1), manpath(5), man(7), catman(8), mandb(8)
Documentation for some packages may be available in other formats, such
as info(1) or HTML.
HISTORY
1990, 1991 – Originally written by John W. Eaton ([email protected]).
Dec 23 1992: Rik Faith ([email protected]) applied bug fixes supplied by
Willem Kasdorp ([email protected]).
30th April 1994 – 23rd February 2000: Wilf. ([email protected])
has been developing and maintaining this package with the help of a few
dedicated people.
30th October 1996 – 30th March 2001: Fabrizio Polacco <fpolacco@de‐
bian.org> maintained and enhanced this package for the Debian project,
with the help of all the community.
31st March 2001 – present day: Colin Watson <[email protected]> is
now developing and maintaining man-db.
BUGS
https://gitlab.com/man-db/man-db/-/issues
https://savannah.nongnu.org/bugs/?group=man-db
2.12.0 2023-09-23 MAN(1)