This book is a short guide, not a comprehensive reference. We
cover important, useful aspects of Linux so you can work pro‐
ductively. We do not, however, present every single command
and every last option (our apologies if your favorite was omit‐
ted), nor delve into detail about operating system internals.
Short, sweet, and essential—that’s our motto.
We focus on commands, those pesky little words you type on a
command line to tell a Linux system what to do. Here’s an
example command that counts lines of text in a file, myfle:
wc -l myfile
We’ll cover the most important Linux commands for the aver‐
age user, such as ls (list files), grep (search for text), mplayer
(play audio and video files), and df (measure free disk space).
We touch only briefly on graphical windowing environments
like GNOME and KDE, each of which could fill a Pocket Guide
by itself.
