Creating Custom Man Pages

Man pages have been the primary source for UN*x documentation for a long time. Whenever I create a script that's going to be around for a while, I create documentation in the form of a section 1 man page. This stops my cell phone from ringing on the weekends when the junior sysadmins are looking for my notes.

Some people I know tend to shy away from writing man pages because they believe it's too difficult to learn how to correctly format man pages using troff or groff. Lucky for me, there's a much easier way to get the job done.

Marc Vertes (mvertes@free.fr) has written an excellent GNU AWK script called txt2man, which can run on almost any UN*X-like system, and can convert a flat ASCII text file to the correct man page format. txt2man (currently version 1.5.5-1) is distributed by the Fedora Project and is available from the EPEL Repository. The authors home page is http://mvertes.free.fr/txt2man/.

Once you've downloaded and installed the correct txt2man package for your system, you can get down to the business of creating a man page. First, get your information together into a single ASCII text file. You will still have to apply a specific formatting to your file, but nothing as complicated as troff/groff.

At the command line, type txt2man -h to view the built-in documentation, which will describe what to add to your file so that it gets correctly formatted later. The best example of how to format your text is actually the displayed help itself.

Using the command:

$ txt2man -h 2>&1 | txt2man -T 

will display the built-in help and pipe it through txt2man to produce a formatted man page and preview it with the default pager. The same command, without the "-T" option, will display the troff/groff formatted output itself. If we redirect the output of the command to a file:

$ txt2man -h 2>&1 | txt2man > txt2man.1

and use gzip to compress the resulting file:

$ gzip txt2man.1

we can view the file as a regular man page:

$ man ./txt2man.1.gz

Notice I specified section 1 for my man page. By default, man will look for System Administration commands in section 8 and General Commands in section 1.

Now, all we need to do is copy our new man page to the appropriate directory for our system, as specified in the $MANPATH environment variable, or maybe in /etc/man.conf, depending on your UN*X/Linux distribution. On my RHEL5 systems, I keep my user generated man pages in /usr/local/man:

$ cp ./txt2man.1.gz /usr/local/man

Finally, I update the whatis database with:

# /usr/sbin/makewhatis

and now my man page is available to all users.