Running Linux, Third Edition

Manual Pages

The most empowering information you can get is how to conduct your own research. Following this precept, we’ll now tell you about the online help system that comes built in to Unix systems. It is called manual pages, or man pages for short.

Actually, manual pages are not quite the boon they ought to be. This is because they are short and take a lot of Unix background for granted. Each one focuses on a particular command and rarely helps you decide why you should use that command. Still, they are critical. Commands can vary slightly on different Unix systems, and the manual pages are the most reliable way to find out what your system does. The Linux Documentation Project deserves a lot of credit for the incredible number of hours they have put into creating manual pages. To find out about a command, enter a command like:

$ man ls

Manual pages are divided into different sections depending on what they are for. User commands are in section 1, Unix system calls in section 2, and so on. The sections that will interest you most are 1, 5 (file formats), and 8 (system administration commands). When you view man pages online, the section numbers are conceptual; you can optionally specify them when searching for a command:

$ man 1 ls

But if you consult a hard-copy manual, you’ll find it divided into actual sections according to the numbering scheme. Sometimes an entry in two different sections can have the same name. (For instance, chmod is both a command and a system call.) ...