Goals for this Hour

In this hour, you learn

• All about the ls command

• About special ls command flags

• How to create files with touch

• How to check disk space usage with du

• How to check available disk space with df

• How to shrink big files with compress

Your first hours focused on some of the basic UNIX commands, particularly those for interacting with the system to accomplish common tasks. In this hour, you expand that knowledge by analyzing characteristics of the system you're using, and you learn a raft of commands that let you create your own UNIX workspace. You also learn more about the UNIX file system and how UNIX interprets command lines. In addition to the cd and pwd commands that you learned in the preceding hour, you learn how to use ls to wander in the file system and see what files are kept where.

Unlike in the Windows and Macintosh operating systems, information about the UNIX system is often difficult to obtain. In this hour, you learn easy ways to ascertain how much disk space you're using, with the du command. You also learn how to interpret the oft-confusing output of the df command, which enables you to see instantly how much total disk space is available on your UNIX system.

This hour concludes with a discussion of the compress command, which enables you to shrink the size of any file or set of files.