Section 4.1. Introduction

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4.1. Introduction

In this chapter, I introduce about thirty useful utilities. Rather than describe them in alphabetical order, I've grouped them into fairly logical sets, as shown in Figure 4-1.

Figure 4-1. Advanced Linux/GNU utilities.

Section	Utilities
Filtering files	egrep, fgrep, grep, uniq
Sorting files	sort
Comparing files	cmp, diff
Archiving files	tar, cpio
Searching for files	find
Scheduling commands	at, crontab
Programmable text processing	gawk, perl
Hard and soft links	ln
Switching users	su
Transforming files	gzip, gunzip, sed, tr, ul, zcat
Looking at raw file contents	od
Mounting file systems	mount, umount
Identifying shells	whoami
Timing execution of a command	time

The remainder of this chapter goes through each group in turn, describing the utilities using worked examples.