Difference between revisions of "Man page"

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{{Lowercase title}}
 
[[Category:System administration]]
 
[[Category:System administration]]
[[ar:Man Page]]
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[[ar:Man page]]
[[ko:Man Page]]
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[[es:Man page]]
[[ru:Man Page]]
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[[ja:Man ページ]]
[[zh-CN:Man Page]]
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[[ko:Man page]]
{{Article summary start|Summary}}
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[[ru:Man page]]
{{Article summary text|Information on man pages, along with recommendations on how to improve their usage}}
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[[zh-cn:Man page]]
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'''man pages'''—abbreviation for "manual pages"—are the extensive documentation that comes preinstalled with almost all substantial UNIX-like operating systems, including Arch Linux. The command used to display them is {{Ic|man}}.
{{Article summary heading|Related}}
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{{Article summary wiki|}}
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-->
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{{Article summary end}}
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{{DISPLAYTITLE:man pages}}
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'''man pages''' (abbreviation for "manual pages") are the extensive documentation that comes preinstalled with almost all substantial UNIX-like operating systems, including Arch Linux. The command used to display them is {{Ic|man}}.
+
  
 
In spite of their scope, man pages are designed to be self-contained documents, consequentially limiting themselves to referring to other man pages when discussing related subjects. This is in sharp contrast with the hyperlink-aware info files, GNU's attempt at replacing the traditional man page format.
 
In spite of their scope, man pages are designed to be self-contained documents, consequentially limiting themselves to referring to other man pages when discussing related subjects. This is in sharp contrast with the hyperlink-aware info files, GNU's attempt at replacing the traditional man page format.
  
==Accessing Man Pages==
+
[[Core utilities#less|less]] is the default pager used with ''man''.
 +
 
 +
== Accessing man pages ==
 
To read a man page, simply enter:
 
To read a man page, simply enter:
  
 
  $ man ''page_name''
 
  $ man ''page_name''
  
Manuals are sorted into several sections:
+
Manuals are sorted into several sections. For a full listing see the section entitled "Sections of the manual pages" in {{ic|man man-pages}}.
# General commands
+
# System calls (functions provided by the kernel)
+
# Library calls (C library functions)
+
# Special files (usually found in /dev) and drivers
+
# File formats and conventions
+
# Games
+
# Miscellaneous (including conventions)
+
# System administration commands (usually requiring root privileges) and daemons
+
  
 
Man pages are usually referred to by their name, followed by their section number in parentheses. Often there are multiple man pages of the same name, such as man(1) and man(7). In this case, give man the section number followed by the name of the man page, for example:
 
Man pages are usually referred to by their name, followed by their section number in parentheses. Often there are multiple man pages of the same name, such as man(1) and man(7). In this case, give man the section number followed by the name of the man page, for example:
Line 37: Line 26:
 
to read the man page on {{Ic|/etc/passwd}}, rather than the {{Ic|passwd}} utility.
 
to read the man page on {{Ic|/etc/passwd}}, rather than the {{Ic|passwd}} utility.
  
Very brief descriptions of programs can be read out of man pages without displaying the whole page using the {{Ic|whatis}} command. For example, for a brief description of ls, type:
+
One-line descriptions of man pages can be displayed using the {{Ic|whatis}} command. For example, for a brief description of the man page sections about {{ic|ls}}, type:
 
+
{{hc|$ whatis ls|ls (1p)              - list directory contents
$ whatis ls
+
ls (1)              - list directory contents}}
 
+
and {{Ic|whatis}} will output "list directory contents."
+
  
==Format==
+
== Format ==
Man pages all follow a fairly standard format, which helps in navigating them. Some sections which are often present include:
+
Man pages all follow a fairly standard format, which helps in navigating them. See the section entitled "Sections within a manual page" in {{ic|man man-pages}}.
* NAME - The name of the command and a one-line statement of its purpose.
+
* SYNOPSIS - A list of the options and arguments a command takes or the parameters the function takes and its header file.
+
* DESCRIPTION - A more in depth description of a command or function's purpose and workings.
+
* EXAMPLES - Common examples, usually ranging from the simple to the relatively complex.
+
* OPTIONS - Descriptions of each of the options a command takes and what they do.
+
* EXIT STATUS - The meanings of different exit codes.
+
* FILES - Files related to a command or function.
+
* BUGS - Problems with the command or function that are pending repair. Also known as KNOWN BUGS.
+
* SEE ALSO - A list of related commands or functions.
+
* AUTHOR, HISTORY, COPYRIGHT, LICENSE, WARRANTY - Information about the program, its past, its terms of use, and its creator.
+
  
==Searching manuals==
+
== Searching manuals ==
Whilst the {{Ic|man}} utility allows users to display man pages, a problem arises when one knows not the exact name of the desired manual page in the first place! Fortunately, the {{Ic|-k}} or {{Ic|--apropos}} options can be used to search the manual page descriptions for instances of a given keyword.
+
Even though the {{Ic|man}} utility allows users to display man pages, and search their contents via ''less'', a problem arises when one knows not the exact name of the desired manual page in the first place! Fortunately, the {{Ic|-k}} or {{Ic|--apropos}} options can be used to search the manual page descriptions for instances of a given keyword.
  
 
The research feature is provided by a dedicated cache. By default you may not have any cache built and all your searches will give you the ''nothing appropriate'' result. You can generate the cache or update it by running
 
The research feature is provided by a dedicated cache. By default you may not have any cache built and all your searches will give you the ''nothing appropriate'' result. You can generate the cache or update it by running
Line 81: Line 58:
 
  $ man -K password
 
  $ man -K password
  
==Colored man pages==
+
== Colored man pages ==
Color-enabled man pages allow for a clearer presentation and easier digestion of the content.
+
There are two prevalent methods for achieving colored man pages: using {{Ic|less}}, or opting for {{Ic|most}}.
+
  
===Using {{ic|less}} (Recommended) ===
+
See [[Color output in console#man]].
:<small>''Source: [http://linuxtidbits.wordpress.com/2009/03/23/less-colors-for-man-pages/ Less Colors For Man Pages | Linux Tidbits]''</small>
+
This method has the advantage that {{Ic|less}} has a bigger feature set than {{Ic|most}}, and is the default for viewing man pages.
+
  
Add the following to a shell configuration file. For [[Bash]] it would be:
+
== Dynamic page width ==
{{hc|~/.bashrc|
+
 
 +
{{Accuracy|How is this dynamic? If you later resize the terminal window, the line breaks will still become wrong.}}
 +
 
 +
The man page width is controlled by the {{Ic|MANWIDTH}} environment variable.
 +
 
 +
If the number of columns in the terminal is too small (e.g. the window width is narrow), the line breaks will be wrong. This can be very disturbing for reading. You can fix this by setting the MANWIDTH on {{Ic|man}} invocation. With {{Ic|Bash}}, that would be:
 +
 
 +
{{Hc|~/.bashrc|
 
<nowiki>man() {
 
<nowiki>man() {
     env LESS_TERMCAP_mb=$'\E[01;31m' \
+
     local width=$(tput cols)
     LESS_TERMCAP_md=$'\E[01;38;5;74m' \
+
     [ $width -gt $MANWIDTH ] && width=$MANWIDTH
    LESS_TERMCAP_me=$'\E[0m' \
+
     env MANWIDTH=$width \
    LESS_TERMCAP_se=$'\E[0m' \
+
    LESS_TERMCAP_so=$'\E[38;5;246m' \
+
     LESS_TERMCAP_ue=$'\E[0m' \
+
    LESS_TERMCAP_us=$'\E[04;38;5;146m' \
+
 
     man "$@"
 
     man "$@"
 
}
 
}
 
</nowiki>}}
 
</nowiki>}}
  
To customize the colors, see [[Wikipedia:ANSI escape code]] for reference.
+
Feel free to combine this function with the [[#Colored man pages|color settings]].
 
+
===Using {{ic|most}} (Not recommended)===
+
The basic function of 'most' is similar to {{Ic|less}} and {{Ic|more}}, but it has a smaller feature set. Configuring most to use colors is easier than using less, but additional configuration is necessary to make most behave like less.
+
Install {{Pkg|most}} using [[pacman]]:
+
# pacman -S most
+
 
+
Edit {{ic|/etc/man_db.conf}}, uncomment the pager definition and change it to:
+
DEFINE    pager    most -s
+
Test the new setup by typing:
+
$ man whatever_man_page
+
 
+
Modifying the color values requires editing {{ic|~/.mostrc}} (creating the file if it is not present) or editing {{ic|/etc/most.conf}} for system-wide changes. Example {{ic|~/.mostrc}}:
+
% Color settings
+
color normal lightgray black
+
color status yellow blue
+
color underline yellow black
+
color overstrike brightblue black
+
Another example showing keybindings similar to {{Ic|less}} (jump to line is set to 'J'):
+
% less-like keybindings
+
unsetkey "^K"
+
unsetkey "g"
+
unsetkey "G"
+
unsetkey ":"
+
+
setkey next_file ":n"
+
setkey find_file ":e"
+
setkey next_file ":p"
+
setkey toggle_options ":o"
+
setkey toggle_case ":c"
+
setkey delete_file ":d"
+
setkey exit ":q"
+
+
setkey bob "g"
+
setkey eob "G"
+
setkey down "e"
+
setkey down "E"
+
setkey down "j"
+
setkey down "^N"
+
setkey up "y"
+
setkey up "^Y"
+
setkey up "k"
+
setkey up "^P"
+
setkey up "^K"
+
setkey page_down "f"
+
setkey page_down "^F"
+
setkey page_up "b"
+
setkey page_up "^B"
+
setkey other_window "z"
+
setkey other_window "w"
+
setkey search_backward "?"
+
setkey bob "p"
+
setkey goto_mark "'"
+
setkey find_file "E"
+
setkey edit "v"
+
 
+
=== Colored man pages on xterm or rxvt-unicode ===
+
 
+
:<small>''Source: [http://pub.ligatura.org/fs/xfree86/xresources/xterm XFree resources file for XTerm program]''</small>{{linkrot|2013|09|10}}
+
 
+
A quick way to add color to manual pages viewed on {{Pkg|xterm}}/{{Ic|uxterm}} or {{Pkg|rxvt-unicode}} is to modify {{ic|~/.Xresources}}.
+
 
+
==== xterm ====
+
*VT100.colorBDMode:    true
+
*VT100.colorBD:        red
+
*VT100.colorULMode:    true
+
*VT100.colorUL:        cyan
+
 
+
which ''replaces'' the decorations with the colors.  Also add:
+
 
+
*VT100.veryBoldColors: 6
+
 
+
if you want colors and decorations (bold or underline) ''at the same time''.  See {{ic|man xterm}} for a description of the {{ic|veryBoldColors}} resource.
+
 
+
==== rxvt-unicode ====
+
URxvt.colorIT:      #87af5f
+
URxvt.colorBD:      #d7d7d7
+
URxvt.colorUL:      #87afd7
+
 
+
Run:
+
$ xrdb -load ~/.Xresources
+
 
+
Launch a new {{Ic|xterm/uxterm}} or {{Ic|rxvt-unicode}} and you should see colorful man pages.
+
This combination puts colors to '''bold''' and <u>underlined</u> words in {{Ic|xterm/uxterm}} or to '''bold''', <u>underlined</u>, and ''italicized'' text in {{Ic|rxvt-unicode}}. You can play with different combinations of these attributes (see the [http://pub.ligatura.org/fs/xfree86/xresources/xterm sources]{{linkrot|2013|09|10}} of this item).
+
  
 
== Reading local man pages ==
 
== Reading local man pages ==
Instead of the standard interface, using browsers such as lynx and [[Firefox]] to view man pages allows users to reap info pages' main benefit: hyperlinked text.
+
Instead of the standard interface, using browsers such as {{Pkg|lynx}} and [[Firefox]] to view man pages allows users to reap info pages' main benefit of hyperlinked text. Alternatives include the following:
  
[[KDE]] users can read man pages in Konqueror using:
+
* [[KDE]] users can read man pages in Konqueror using {{ic|man:<name>}}.
man:<name>
+
* {{pkg|xorg-xman}} provides a categorized look at man pages in [[X]].
From the [[Official Repositories]] come two other possibilities:
+
* The [[GNOME]] Help Browser {{pkg|yelp}} can be used via {{ic|yelp man:<name>}}.
  
1. {{pkg|xorg-xman}} provides a categorized look at man pages in [[X]].
+
=== Converting to browser-readable HTML ===
 +
==== mdocml ====
 +
Install {{AUR|mdocml}} from [[AUR]]. To convert a page, for example {{ic|free(1)}}:
 +
$ gunzip -c /usr/share/man/man1/free.1.gz | mandoc -Thtml -Ostyle=style.css 1> free.html
  
2. The [[GNOME]] Help Browser {{pkg|yelp}} is a more neat way but has some dependencies.
+
Now open the file called {{ic|free.html}} in your favourite browser.
  
=== Converting to browser-readable HTML ===
+
==== man2html ====
 
First, install {{Pkg|man2html}} from the official repositories.
 
First, install {{Pkg|man2html}} from the official repositories.
  
Line 208: Line 104:
 
  $ man free | man2html -bare > ~/free.txt
 
  $ man free | man2html -bare > ~/free.txt
  
 +
==== man -H ====
 
The GNU implementation of man in the Arch repositories also has the ability to do this on its own:
 
The GNU implementation of man in the Arch repositories also has the ability to do this on its own:
 
  $ man -H free
 
  $ man -H free
  
This will read your {{ic|BROWSER}} environment variable to determine the browser. You can override this by passing the binary to the {{ic|-H}} option.
+
This will read your {{ic|BROWSER}} [[environment variable]] to determine the browser. You can override this by passing the binary to the {{ic|-H}} option.
 +
 
 +
==== roffit ====
 +
First install {{AUR|roffit}}{{Broken package link|{{aur-mirror|roffit}}}} from [[AUR]].
 +
 
 +
To convert a man page:
 +
 
 +
$ gunzip -c /usr/share/man/man1/free.1.gz | roffit > free.html
  
 
=== Converting to PDF ===
 
=== Converting to PDF ===
Line 218: Line 122:
 
Caveats: Fonts are generally limited to Times at hardcoded sizes. There are no hyperlinks. Some man pages were specifically designed for terminal viewing, and won't look right in PS or PDF form.
 
Caveats: Fonts are generally limited to Times at hardcoded sizes. There are no hyperlinks. Some man pages were specifically designed for terminal viewing, and won't look right in PS or PDF form.
  
The following perl script converts man pages to PDFs, caches the PDFs in the {{ic|$HOME/.manpdf/}} directory, and calls a PDF viewer, specifically [https://www.archlinux.org/packages/community/x86_64/mupdf/ mupdf].
+
The following perl script converts man pages to PDFs, caches the PDFs in the {{ic|$HOME/.manpdf/}} directory, and calls a PDF viewer, specifically {{Pkg|mupdf}}.
  
 
{{hc|Usage: manpdf [<section>] <manpage>|<nowiki>
 
{{hc|Usage: manpdf [<section>] <manpage>|<nowiki>
Line 269: Line 173:
 
*[http://www.unix.com/man-page/OpenSolaris/1/man/ ''The UNIX and Linux Forums Man Page Repository'']
 
*[http://www.unix.com/man-page/OpenSolaris/1/man/ ''The UNIX and Linux Forums Man Page Repository'']
 
*[http://manpages.ubuntu.com/ ''Ubuntu Manpage Repository'']
 
*[http://manpages.ubuntu.com/ ''Ubuntu Manpage Repository'']
 +
 +
{{Warning|Some distributions provide patched or outdated man pages that differ from those provided by Arch. Exercise caution when using online man pages.}}
  
 
==Noteworthy manpages==
 
==Noteworthy manpages==
Line 301: Line 207:
 
* pacman.conf(5)
 
* pacman.conf(5)
  
==See also==
+
== See also ==
  
* [[General Recommendations]] - General Recommendations for Arch
+
* [http://wiki.gentoo.org/wiki/Man_page man page - Gentoo wiki article]
 +
* [http://unix.stackexchange.com/a/147 Setting colors for less] and [http://unix.stackexchange.com/a/6357 solving related problems] (threads on StackExchange)
 +
* [https://linuxtidbits.wordpress.com/2013/08/21/wtfm-write-the-fine-manual-with-pod2man-text-converter/ Write The Fine Manual with pod2man]

Latest revision as of 15:09, 11 August 2016

man pages—abbreviation for "manual pages"—are the extensive documentation that comes preinstalled with almost all substantial UNIX-like operating systems, including Arch Linux. The command used to display them is man.

In spite of their scope, man pages are designed to be self-contained documents, consequentially limiting themselves to referring to other man pages when discussing related subjects. This is in sharp contrast with the hyperlink-aware info files, GNU's attempt at replacing the traditional man page format.

less is the default pager used with man.

Accessing man pages

To read a man page, simply enter:

$ man page_name

Manuals are sorted into several sections. For a full listing see the section entitled "Sections of the manual pages" in man man-pages.

Man pages are usually referred to by their name, followed by their section number in parentheses. Often there are multiple man pages of the same name, such as man(1) and man(7). In this case, give man the section number followed by the name of the man page, for example:

$ man 5 passwd

to read the man page on /etc/passwd, rather than the passwd utility.

One-line descriptions of man pages can be displayed using the whatis command. For example, for a brief description of the man page sections about ls, type:

$ whatis ls
ls (1p)              - list directory contents
ls (1)               - list directory contents

Format

Man pages all follow a fairly standard format, which helps in navigating them. See the section entitled "Sections within a manual page" in man man-pages.

Searching manuals

Even though the man utility allows users to display man pages, and search their contents via less, a problem arises when one knows not the exact name of the desired manual page in the first place! Fortunately, the -k or --apropos options can be used to search the manual page descriptions for instances of a given keyword.

The research feature is provided by a dedicated cache. By default you may not have any cache built and all your searches will give you the nothing appropriate result. You can generate the cache or update it by running

# mandb

You should run it everytime a new manpage is installed.

Now you can begin your search. For example, to search for man pages related to "password":

$ man -k password

or:

$ man --apropos password

This is equivalent to calling the apropos command:

$ apropos password

The given keyword is interpreted as a regular expression by default.

If you want to do a more in-depth search by matching the keywords found in the whole articles, you can use the -K option:

$ man -K password

Colored man pages

See Color output in console#man.

Dynamic page width

Tango-inaccurate.pngThe factual accuracy of this article or section is disputed.Tango-inaccurate.png

Reason: How is this dynamic? If you later resize the terminal window, the line breaks will still become wrong. (Discuss in Talk:Man page#)

The man page width is controlled by the MANWIDTH environment variable.

If the number of columns in the terminal is too small (e.g. the window width is narrow), the line breaks will be wrong. This can be very disturbing for reading. You can fix this by setting the MANWIDTH on man invocation. With Bash, that would be:

~/.bashrc
man() {
    local width=$(tput cols)
    [ $width -gt $MANWIDTH ] && width=$MANWIDTH
    env MANWIDTH=$width \
    man "$@"
}

Feel free to combine this function with the color settings.

Reading local man pages

Instead of the standard interface, using browsers such as lynx and Firefox to view man pages allows users to reap info pages' main benefit of hyperlinked text. Alternatives include the following:

  • KDE users can read man pages in Konqueror using man:<name>.
  • xorg-xman provides a categorized look at man pages in X.
  • The GNOME Help Browser yelp can be used via yelp man:<name>.

Converting to browser-readable HTML

mdocml

Install mdocmlAUR from AUR. To convert a page, for example free(1):

$ gunzip -c /usr/share/man/man1/free.1.gz | mandoc -Thtml -Ostyle=style.css 1> free.html

Now open the file called free.html in your favourite browser.

man2html

First, install man2html from the official repositories.

Now, convert a man page:

$ man free | man2html -compress -cgiurl man$section/$title.$section$subsection.html > ~/man/free.html

Another use for man2html is exporting to raw, printer-friendly text:

$ man free | man2html -bare > ~/free.txt

man -H

The GNU implementation of man in the Arch repositories also has the ability to do this on its own:

$ man -H free

This will read your BROWSER environment variable to determine the browser. You can override this by passing the binary to the -H option.

roffit

First install roffitAUR[broken link: archived in aur-mirror] from AUR.

To convert a man page:

$ gunzip -c /usr/share/man/man1/free.1.gz | roffit > free.html

Converting to PDF

man pages have always been printable: they are written in troff, which is fundamentally a typesetting language. If you have ghostscript installed, converting a man page to PDF is actually very easy: man -t <manpage> | ps2pdf - <pdf>. This google image search should give you an idea of what the result looks like; it may not be to everybody's liking.

Caveats: Fonts are generally limited to Times at hardcoded sizes. There are no hyperlinks. Some man pages were specifically designed for terminal viewing, and won't look right in PS or PDF form.

The following perl script converts man pages to PDFs, caches the PDFs in the $HOME/.manpdf/ directory, and calls a PDF viewer, specifically mupdf.

Usage: manpdf [<section>] <manpage>
#!/usr/bin/perl
use File::stat;

$pdfdir = $ENV{"HOME"}."/.manpdf";
-d $pdfdir || mkdir $pdfdir || die "can't create $pdfdir";
$manpage = $ARGV[0];
chop($manpath = `man -w $manpage`);
die if $?;

$maninfo = stat($manpath) or die;
$manpath =~ s@.*/man./(.*)(\.(gz|bz2))?$@$1@;
$pdfpath = "$pdfdir/$manpath.pdf";
$pdftime = 0;
if (-f $pdfpath) {
    $pdfinfo = stat($pdfpath) or die;
    $pdftime = $pdfinfo->mtime;
}
if (!-f $pdfpath || $maninfo->mtime > $pdftime) {
    system "man -t $manpage | ps2pdf -dPDFSETTINGS=/screen - $pdfpath";
}
die if !-f $pdfpath;
if (!fork) {
    open(STDOUT, "/dev/null");
    open(STDERR, "/dev/null");
    exec "mupdf", "-r", "96", $pdfpath;
    #exec "acroread", $pdfpath;
}

Online Man Pages

There are several online databases of man pages, including:

Warning: Some distributions provide patched or outdated man pages that differ from those provided by Arch. Exercise caution when using online man pages.

Noteworthy manpages

Here follows a non-exhaustive list of noteworthy pages that might help you understand a lot of things more in-depth. Some of them might serve as a good reference (like the ascii table).

  • ascii(7)
  • boot(7)
  • charsets(7)
  • chmod(1)
  • credentials(7)
  • fstab(5)
  • hier(7)
  • systemd(1)
  • locale(1P)(5)(7)
  • printf(3)
  • proc(5)
  • regex(7)
  • signal(7)
  • term(5)(7)
  • termcap(5)
  • terminfo(5)
  • utf-8(7)

More generally, have a look at category 7 pages:

$ man -s 7 -k ".*" 

Arch Linux specific pages:

  • archlinux(7)
  • mkinitcpio(8)
  • pacman(8)
  • pacman-key(8)
  • pacman.conf(5)

See also