Introduction

The commands in this section deal with the compression, storage, and extraction of system files. Typically, you'll want to compress and store at the same time no need to take up 200M of storage space when 100M will do.

One of the biggest differences between a professional systems administrator and some incompetent who knows a few commands is that the systems administrator has a good backup strategy.

A full backup saves every file within some specified set. An incremental backup backs up only those files that have been changed since the previous backup. The idea behind making incremental backups is that the bulk of the files on the system never change, so it's unnecessarily expensive in terms of time and disk space to keep copying them over and over. The downside is that when you're mixing full and incremental backups, it's more complicated to restore the system to its original state after a disaster.

Of the compression utilities listed here, the two most popular are probably compress and gzip. Compress (.Z file extension) used to go out with all UNIX distributions, so you see it around a lot. Gzip (.gz file extension) is more efficient and happens to have fewer license restrictions, so it's probably the best choice for day-to-day work.