//man(1) / 憋错料

man(1) man(1)

NAME

man - format and display the on-line manual pages

SYNOPSIS

man [-acdfFhkKtwW] [--path] [-m system] [-p string] [-C config_file]

[-M pathlist] [-P pager] [-B browser] [-H htmlpager] [-S section_list]

[section] name ...

DESCRIPTION

man formats and displays the on-line manual pages. If you specify sec-

tion, man only looks in that section of the manual. name is normally

the name of the manual page, which is typically the name of a command,

function, or file. However, if name contains a slash (/) then man

interprets it as a file specification, so that you can do man ./foo.5

or even man /cd/foo/bar.1.gz.

See below for a description of where man looks for the manual page

files.

OPTIONS

-C config_file

Specify（指定） the configuration file to use; the default is

/etc/man.config. (See man.config(5).)

-M path

Specify the list of directories to search for man pages. Sepa-

rate the directories with colons（冒号）. An empty list is the same as

not specifying -M at all. See SEARCH PATH FOR MANUAL PAGES.

-P pager

Specify which pager to use. This option overrides the MANPAGER

environment variable, which in turn overrides the PAGER vari-

able. By default, man uses /usr/bin/less -is.

-B Specify which browser to use on HTML files. This option over-

rides the BROWSER environment variable. By default, man uses

/usr/bin/less-is,

-H Specify a command that renders HTML files as text. This option

overrides the HTMLPAGER environment variable. By default, man

uses /bin/cat,

-S section_list

List is a colon separated list of manual sections to search.

This option overrides the MANSECT environment variable.

-a By default, man will exit after displaying the first manual page

it finds. Using this option forces man to display all the man-

ual pages that match name, not just the first.

-c Reformat the source man page, even when an up-to-date cat page

exists. This can be meaningful if the cat page was formatted

for a screen with a different number of columns, or if the pre-

formatted page is corrupted.

-d Don’t actually display the man pages, but do print gobs of

debugging information.

-D Both display and print debugging info.

-f Equivalent to whatis.

-F or --preformat

Format only - do not display.

-h Print a help message and exit.

-k Equivalent to apropos.

-K Search for the specified string in *all* man pages. Warning:

this is probably very slow! It helps to specify a section.

(Just to give a rough idea, on my machine this takes about a

minute per 500 man pages.)

-m system

Specify an alternate set of man pages to search based on the

system name given.

-p string

Specify the sequence of preprocessors to run before nroff or

troff. Not all installations will have a full set of preproces-

sors. Some of the preprocessors and the letters used to desig-

nate them are: eqn (e), grap (g), pic (p), tbl (t), vgrind (v),

refer (r). This option overrides the MANROFFSEQ environment

variable.

-t Use /usr/bin/groff -Tps -mandoc to format the manual page, pass-

ing the output to stdout. The default output format of

/usr/bin/groff -Tps -mandoc is Postscript, refer to the manual

page of /usr/bin/groff -Tps -mandoc for ways to pick an alter-

nate format.

Depending on the selected format and the availability of printing

devices, the output may need to be passed through some filter or

another before being printed.

-w or --path

Don’t actually display the man pages, but do print the loca-

tion(s) of the files that would be formatted or displayed. If no

argument is given: display (on stdout) the list of directories

that is searched by man for man pages. If manpath is a link to

man, then "manpath" is equivalent to "man --path".

-W Like -w, but print file names one per line, without additional

information. This is useful in shell commands like man -aW man

| xargs ls -l

CAT PAGES

Man will try to save the formatted man pages, in order to save format-

ting time the next time these pages are needed. Traditionally, format-

ted versions of pages in DIR/manX are saved in DIR/catX, but other map-

pings from man dir to cat dir can be specified in /etc/man.config. No

cat pages are saved when the required cat directory does not exist. No

cat pages are saved when they are formatted for a line length different

from 80. No cat pages are saved when man.config contains the line

NOCACHE.

It is possible to make man suid to a user man. Then, if a cat directory

has owner man and mode 0755 (only writable by man), and the cat files

have owner man and mode 0644 or 0444 (only writable by man, or not

writable at all), no ordinary user can change the cat pages or put

other files in the cat directory. If man is not made suid, then a cat

directory should have mode 0777 if all users should be able to leave

cat pages there.

The option -c forces reformatting a page, even if a recent cat page

exists.

HTML PAGES

Man will find HTML pages if they live in directories named as expected

to be ".html", thus a valid name for an HTML version of the ls(1) man

page would be /usr/share/man/htmlman1/ls.1.html.

SEARCH PATH FOR MANUAL PAGES

man uses a sophisticated method of finding manual page files, based on

the invocation options and environment variables, the /etc/man.config

configuration file, and some built in conventions and heuristics.

First of all, when the name argument to man contains a slash (/), man

assumes it is a file specification itself, and there is no searching

involved.

But in the normal case where name doesn’t contain a slash, man searches

a variety of directories for a file that could be a manual page for the

topic named.

If you specify the -M pathlist option, pathlist is a colon-separated

list of the directories that man searches.

If you don’t specify -M but set the MANPATH environment variable, the

value of that variable is the list of the directories that man

searches.

If you don’t specify an explicit path list with -M or MANPATH, man

develops its own path list based on the contents of the configuration

file /etc/man.config. The MANPATH statements in the configuration file

identify particular directories to include in the search path.

Furthermore, the MANPATH_MAP statements add to the search path depend-

ing on your command search path (i.e. your PATH environment variable).

For each directory that may be in the command search path, a MAN-

PATH_MAP statement specifies a directory that should be added to the

search path for manual page files. man looks at the PATH variable and

adds the corresponding directories to the manual page file search path.

Thus, with the proper use of MANPATH_MAP, when you issue the command

man xyz, you get a manual page for the program that would run if you

issued the command xyz.

In addition, for each directory in the command search path (we’ll call

it a "command directory") for which you do not have a MANPATH_MAP

statement, man automatically looks for a manual page directory "nearby"

namely as a subdirectory in the command directory itself or in the par-

ent directory of the command directory.

You can disable the automatic "nearby" searches by including a NOAU-

TOPATH statement in /etc/man.config.

In each directory in the search path as described above, man searches

for a file named topic.section, with an optional suffix on the section

number and possibly a compression suffix. If it doesn’t find such a

file, it then looks in any subdirectories named manN or catN where N is

the manual section number. If the file is in a catN subdirectory, man

assumes it is a formatted manual page file (cat page). Otherwise, man

assumes it is unformatted. In either case, if the filename has a known

compression suffix (like .gz), man assumes it is gzipped.

If you want to see where (or if) man would find the manual page for a

particular topic, use the --path (-w) option.

ENVIRONMENT

MANPATH

If MANPATH is set, man uses it as the path to search for manual

page files. It overrides the configuration file and the auto-

matic search path, but is overridden by the -M invocation

option. See SEARCH PATH FOR MANUAL PAGES.

MANPL If MANPL is set, its value is used as the display page length.

Otherwise, the entire man page will occupy one (long) page.

MANROFFSEQ

If MANROFFSEQ is set, its value is used to determine the set of

preprocessors run before running nroff or troff. By default,

pages are passed through the tbl preprocessor before nroff.

MANSECT

If MANSECT is set, its value is used to determine which manual

sections to search.

MANWIDTH

If MANWIDTH is set, its value is used as the width manpages

should be displayed. Otherwise the pages may be displayed over

the whole width of your screen.

MANPAGER

If MANPAGER is set, its value is used as the name of the program

to use to display the man page. If not, then PAGER is used. If

that has no value either, /usr/bin/less -is is used.

BROWSER

The name of a browser to use for displaying HTML manual pages.

If it is not set, /usr/bin/less -is is used.

HTMLPAGER

The command to use for rendering HTML manual pages as text. If

it is not set, /bin/cat is used.

LANG If LANG is set, its value defines the name of the subdirectory

where man first looks for man pages. Thus, the command ‘LANG=dk

man 1 foo’ will cause man to look for the foo man page in

.../dk/man1/foo.1, and if it cannot find such a file, then in

.../man1/foo.1, where ... is a directory on the search path.

NLSPATH, LC_MESSAGES, LANG

The environment variables NLSPATH and LC_MESSAGES (or LANG when

the latter does not exist) play a role in locating the message

catalog. (But the English messages are compiled in, and for

English no catalog is required.) Note that programs like col(1)

called by man also use e.g. LC_CTYPE.

PATH PATH helps determine the search path for manual page files. See

SEARCH PATH FOR MANUAL PAGES.

SYSTEM SYSTEM is used to get the default alternate system name (for use

with the -m option).

BUGS

The -t option only works if a troff-like program is installed.

If you see blinking \255 or <AD> instead of hyphens, put ‘LESS-

CHARSET=latin1’ in your environment.

TIPS

If you add the line

(global-set-key [(f1)] (lambda () (interactive) (manual-entry

(current-word))))

to your .emacs file, then hitting F1 will give you the man page for the

library call at the current cursor position.

To get a plain text version of a man page, without backspaces and

underscores, try

# man foo | col -b > foo.mantxt