man man

written on Wednesday, July 10, 2013

People learn things in all kinds of different ways. For me, nothing beats just using something in a real world application. But there is a lot to be said for randomly poring through the reference material. If you have Linux installed then you have ready access to the the world's most arcane and obtuse reference. Unix man pages!

:~$ apropos . | wc -l

You can use the apropos command to search these manual pages and their descriptions. Or you can use "." to match all of them, and pipe them to wc -l which tells you how many lines of output it gave. On my system there are 7015.

In the interest of brute force learning I am making an attempt to read them all over the next year. That is about 20 a day. Manageable.

On Linux, man pages are divided into 9 different sections. Described below. This table is lifted from man man, natch.

  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 eg /etc/passwd
  6. Games
  7. Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7)
  8. System administration commands (usually only for root)
  9. Kernel routines [Non standard]
You can limit your search to sections by passing -s to apropos. The entry counts for each section on my system are:
:~$ apropos -s 1 . | wc -l
:~$ apropos -s 2 . | wc -l
:~$ apropos -s 3 . | wc -l
:~$ apropos -s 4 . | wc -l
:~$ apropos -s 5 . | wc -l
:~$ apropos -s 6 . | wc -l
:~$ apropos -s 7 . | wc -l
:~$ apropos -s 8 . | wc -l
:~$ apropos -s 9 . | wc -l
.: nothing appropriate.

As you can see the bulk of the entries are for library calls, and shell commands. Since my main goal is to gain a deeper understanding of Linux I think I'm going to start with section 2.

:~$ apropos -s 2 . | less

Will give you a list of my next 21 days worth of reading material. Wish me luck.

This entry was tagged learning and linux