[http://www.gnu.org—The website of the GNU project, which contains](http://www.gnu.org—The website of the GNU project, which contains)
manuals and downloads for lots of command-line software
Linux in a Nutshell by Stephen Figgins, Arnold Robbins, Ellen
Siever, and Robert Love—A dictionary of Linux commands that
includes a wide selection of Linux commands and explanations of what
they do
[http://www.linuxcommand.org—A “one-stop command-line shop” that](http://www.linuxcommand.org—A “one-stop command-line shop” that)
contains a wealth of useful information about the console
The Art of UNIX Programming by Eric Raymond—Focuses on the
philosophy behind UNIX and manages to mix in much about the
command line