Summary

The UNIX System gives you many commands that can be used singly or in combination to perform a wide variety of tasks, and to solve a wide range of problems. They can be thought of as software tools. This chapter has surveyed a number of the most useful tools in the UNIX System toolkit, including tools for finding patterns in files; working with compressed files, modifying structured files; comparing files; and performing numerical computations.

These tools can be used on the command line, as shown in many of these examples, or invoked from scripts. In fact, many of these tools are extremely useful when writing scripts to automate complex tasks. Shell scripting will be discussed in the next chapter. Two very powerful tools for scripting, awk and sed, are discussed in the chapter after that.

Table 19–7 summarizes the commands that were discussed in this chapter.

Table 19–7: Command Summary

Commands	Use	Commands	Use
grep fgrep egrep	Search for text in a file	cmp comm diff dircmp	Compare files or directories
pack compress gzip bzip2	Compress a file See section on compressing files for related commands, such as gunzip and zcat	od strings	View files with unusual characters
tar	Package/extract a set of files	tac	Print a file backward
wc	Count words or lines	pr font	Add simple formatting
nl	Add line numbers	tr	Translate certain characters
cut colrm	Get certain columns or fields	tee	Fork output to a file and to standard output
paste join	Combine files formatted with columns or fields	script	Record all text on the screen
sort	Sort lines	mail	Send mail
uniq	Remove duplicate lines	date	Display the date and time
patch	Update a file to a new version	touch	Update the date on a file
spell ispell	Check spelling	bc dc	Perform calculations