help2man

`help2man` Reference Manual

Overview of help2man
How to Run help2man
--help Recommendations
Including Additional Text in the Output
Using help2man With make
Producing Native Language Manual Pages
- Changing the Location of Message Catalogs
Example help2man Output
Reporting Bugs or Suggestions
Obtaining help2man

`help2man`

help2man produces simple manual pages from the ‘--help’ and ‘--version’ output of other commands.

Overview of `help2man`

help2man is a tool for automatically generating simple manual pages from program output.

Although manual pages are optional for GNU programs other projects, such as Debian require them (see Man Pages in GNU Coding Standards)

This program is intended to provide an easy way for software authors to include a manual page in their distribution without having to maintain that document.

Given a program which produces reasonably standard ‘--help’ and ‘--version’ outputs, help2man can re-arrange that output into something which resembles a manual page.

How to Run `help2man`

The format for running the help2man program is:

help2man [option]… executable

help2man supports the following options:

‘-n string’

‘--name=string’

Use string as the description for the ‘NAME’ paragraph of the manual page.

By default (for want of anything better) this paragraph contains ‘manual page for program version’.

This option overrides an include file ‘[name]’ section (see Including text).

‘-s section’

‘--section section’

Use section as the section for the man page. The default section is 1.

‘-m manual’

‘--manual=manual’

Set the name of the manual section to section, used as a centred heading for the manual page. By default ‘User Commands’ is used for pages in section 1, ‘Games’ for section 6 and ‘System Administration Utilities’ for sections 8 and 1M.

‘-S source’

‘--source=source’

The program source is used as a page footer, and often contains the name of the organisation or a suite of which the program is part. By default the value is the package name and version.

‘-L locale’

‘--locale=locale’

Select output locale (default ‘C’). Both the program and help2man must support the given locale (see Localised man pages).

‘-i file’

‘--include=file’

Include material from file (see Including text).

‘-I file’

‘--opt-include=file’

A variant of ‘--include’ for use in Makefile pattern rules which does not require file to exist.

‘-o file’

‘--output=file’

Send output to file rather than stdout.

‘-p text’

‘--info-page=text’

Name of Texinfo manual.

‘-N’

‘--no-info’

Suppress inclusion of a ‘SEE ALSO’ paragraph directing the reader to the Texinfo documentation.

‘-l’

‘--libtool’

Drop lt- prefix from instances of the program name in the synopsis (libtool creates wrapper scripts in the build directory which invoke foo as .libs/lt-foo).

‘--help’

‘--version’

Show help or version information.

By default help2man passes the standard ‘--help’ and ‘--version’ options to the executable although alternatives may be specified using:

‘-h option’
‘--help-option=option’: Help option string.
‘-v option’
‘--version-option=option’: Version option string.
‘--version-string=string’: Version string.
‘--no-discard-stderr’: Include stderr when parsing option output.

`--help` Recommendations

Here are some recommendations for what to include in your --help output. Including these gives help2man the best chance at generating a respectable man page, as well as benefitting users directly.

See Command-Line Interfaces in GNU Coding Standards and Man Pages in GNU Coding Standards, for the official GNU standards relating to --help and man pages.

A synopsis of how to invoke the program. If different usages of the program have different invocations, then list them all. For example (edited for brevity):
```
Usage: cp [OPTION]... SOURCE DEST
  or:  cp [OPTION]... SOURCE... DIRECTORY
…
```
Use argv[0] for the program name in these synopses, just as it is, with no directory stripping. This is in contrast to the canonical (constant) name of the program which is used in --version.
A very brief explanation of what the program does, including default and/or typical behaviour. For example, here is cp’s:
```
Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.
```
A list of options, indented to column 2. If the program supports one-character options, put those first, then the equivalent long option (if any). If the option takes an argument, include that too, giving it a meaningful name. Align the descriptions in a convenient column, if desired. Note that to be correctly recognised by help2man the description must be separated from the options by at least two spaces and descriptions continued on subsequent lines must start at the same column.
Here again is an (edited) excerpt from cp, showing a short option with an equivalent long option, a long option only, and a short option only:
```
  -a, --archive                same as -dpR
      --backup[=CONTROL]       make a backup of each ...
  -b                           like --backup but ...
```
For programs that take many options, it may be desirable to split the option list into sections such as ‘Global’, ‘Output control’, or whatever makes sense in the particular case. It is usually best to alphabetise (by short option name first, then long) within each section, or the entire list if there are no sections.
Any useful additional information about program behaviour, such as influential environment variables, further explanation of options, etc. For example, cp discusses VERSION_CONTROL and sparse files.
A few examples of typical usage, at your discretion. One good example is usually worth a thousand words of description, so this is highly recommended.
In closing, a line stating how to email bug reports. Typically, mailing-address will be ‘bug-program@gnu.org’; please use this form for GNU programs whenever possible. It’s also good to mention the home page of the program, other mailing lists, etc.

The argp and popt programming interfaces let you specify option descriptions for --help in the same structure as the rest of the option definition; you may wish to consider using these routines for option parsing instead of getopt.

By default help2man has some heuristics for identifying manual page sections: a line consisting of ‘Options:’ for example will cause the following text to appear in the OPTIONS section, and a line beginning with ‘Copyright’ will appear in the COPYRIGHT section. Outside of these heuristics, a line consisting of ‘*Words*’ will start a new section, and ‘Words:’ a new sub-section.

Including Additional Text in the Output

Additional static text may be included in the generated manual page by using the ‘--include’ and ‘--opt-include’ options (see Invoking help2man). While these files can be named anything, for consistency we suggest to use the extension .h2m for help2man include files.

The format for files included with these option is simple:

[section]
text

/pattern/
text

Blocks of verbatim *roff text are inserted into the output either at the start of the given ‘[section]’ (case insensitive), or after a paragraph matching ‘/pattern/’.

Patterns use the Perl regular expression syntax and may be followed by the ‘i’, ‘s’ or ‘m’ modifiers (see perlre(1) in The perlre(1) manual page)

Lines before the first section or pattern which begin with ‘-’ are processed as options. Anything else is silently ignored and may be used for comments, RCS keywords and the like.

The section output order (for those included) is:

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
other
ENVIRONMENT
FILES
EXAMPLES
AUTHOR
REPORTING BUGS
COPYRIGHT
SEE ALSO

Any ‘[name]’ or ‘[synopsis]’ sections appearing in the include file will replace what would have automatically been produced (although you can still override the former with ‘--name’ if required).

Other sections are prepended to the automatically produced output for the standard sections given above, or included at other (above) in the order they were encountered in the include file.

Placement of the text within the section may be explicitly requested by using the syntax ‘[<section]’, ‘[=section]’ or ‘[>section]’ to place the additional text before, in place of, or after the default output respectively.

Using `help2man` With `make`

A suggested use of help2man in Makefiles is to have the manual page depend not on the binary, but on the source file(s) in which the ‘--help’ and ‘--version’ output are defined.

This usage allows a manual page to be generated by the maintainer and included in the distribution without requiring the end-user to have help2man installed.

An example rule for the program prog could be:

prog.1: $(srcdir)/main.c
        -$(HELP2MAN) --output=$@ --name='an example program' ./prog

The value of HELP2MAN may be set in configure.in using either of:

AM_MISSING_PROG(HELP2MAN, help2man)

for automake, or something like:

AC_PATH_PROG(HELP2MAN, help2man, false // No help2man //)

for autoconf alone.

Producing Native Language Manual Pages

Manual pages may be produced for any locale supported by both the program and help2man with the ‘--locale’ (‘-L’) option.

help2man -L fr_FR@euro -o cp.fr.1 cp

See http://translationproject.org/domain/help2man.html for the languages currently supported by help2man, and see Reports for how to submit other translations.

Changing the Location of Message Catalogs

When creating localised manual pages from a program’s build directory it is probable that the translations installed in the standard location will not be (if installed at all) correct for the version of the program being built.

A preloadable library is provided with help2man which will intercept bindtextdomain calls configuring the location of message catalogs for the domain given by $TEXTDOMAIN and override the location to the path given by $LOCALEDIR.

So for example:

mkdir -p tmp/fr/LC_MESSAGES
cp po/fr.gmo tmp/fr/LC_MESSAGES/prog.mo
LD_PRELOAD="/usr/lib/help2man/bindtextdomain.so" \
  LOCALEDIR=tmp \
  TEXTDOMAIN=prog \
  help2man -L fr_FR@euro -i prog.fr.h2m -o prog.fr.1 prog
rm -rf tmp

will cause prog to load the message catalog from ‘tmp’ rather than ‘/usr/share/locale’.

Notes:

The generalisation of ‘fr_FR@euro’ to ‘fr’ in the example above is done by gettext, if a more specific match were available it would also have been re-mapped.
This preload has only been tested against eglibc 2.11.2 and gettext 0.18.1.1 on a GNU/Linux system; let me know if it does (or doesn’t) work for you (see Reports).

Example `help2man` Output

Given a hypothetical program foo which produces the following output:

$ foo --version
GNU foo 1.1

Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Written by A. Programmer.
$ foo --help
GNU `foo' does nothing interesting except serve as an example for
`help2man'.

Usage: foo [OPTION]...

Options:
  -a, --option      an option
  -b, --another-option[=VALUE]
                    another option

      --help        display this help and exit
      --version     output version information and exit

Examples:
  foo               do nothing
  foo --option      the same thing, giving `--option'

Report bugs to <bug-gnu-utils@gnu.org>.

help2man will produce nroff input for a manual page which will be formatted something like this:

FOO(1)                         User Commands                        FOO(1)


NAME
       foo - manual page for foo 1.1

SYNOPSIS
       foo [OPTION]...

DESCRIPTION
       GNU  `foo'  does nothing interesting except serve as an example for
       `help2man'.

OPTIONS
       -a, --option
              an option

       -b, --another-option[=VALUE]
              another option

       --help display this help and exit

       --version
              output version information and exit

EXAMPLES
       foo    do nothing

       foo --option
              the same thing, giving `--option'

AUTHOR
       Written by A. Programmer.

REPORTING BUGS
       Report bugs to <bug-gnu-utils@gnu.org>.

COPYRIGHT
       Copyright © 2011 Free Software Foundation, Inc.
       This is free software;  see  the  source  for  copying  conditions.
       There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
       PARTICULAR PURPOSE.

SEE ALSO
       The full documentation for foo is maintained as a  Texinfo  manual.
       If  the  info and foo programs are properly installed at your site,
       the command

              info foo

       should give you access to the complete manual.


foo 1.1                          May 2011                           FOO(1)

Reporting Bugs or Suggestions

If you find problems or have suggestions about this program or manual, please report them to bug-help2man@gnu.org.

Note to translators: Translations are handled though the Translation Project see http://translationproject.org/html/translators.html for details.

Obtaining `help2man`

The latest version of this distribution is available online from GNU mirrors:

http://ftpmirror.gnu.org/help2man/

If automatic redirection fails, the list of mirrors is at:

http://www.gnu.org/order/ftp.html

Or if need be you can use the main GNU ftp server:

http://ftp.gnu.org/gnu/help2man/

help2man Reference Manual

Table of Contents

Overview of help2man

How to Run help2man

--help Recommendations