Text Processing

Manipulating text files can be a time-consuming process if done manually. The commands in Table A.5 are commonly used to manipulate the contents of text files. These commands normally work by outputting the data to standard out (otherwise known as the screen), so to capture these changes, you normally redirect the output to another text file using the greater-than sign (>). For example:

 sort /etc/passwd > /tmp/users.txt 

Table A.5. Commands Commonly Used to Process Text Files

COMMAND	GENERAL USAGE	DESCRIPTION
expand	expand FILE	Converts tab characters to spaces in the specified file.
joe	joe FILE	Text-editing utility.
nl	nl FILE	Assigns line numbers and displays the specified file.
pr	pr [OPTIONS] FILE	Formats a text file for printing.
sort	sort FILE	Alphabetically sorts and displays the specified file.
unexpand	unexpand FILE	Converts spaces to tab characters in the specified file.
uniq	uniq FILE	Displays all unique lines in the specified file.
vi	vi FILE	Text-editing utility. Use vimtutor for an introduction to this utility.
wc	wc [OPTIONS] FILE	Returns the number of lines, words, and characters in the specified file.