Linux® Command Line and Shell Scripting Bible, Second Edition

Appendix B

Quick Guide to sed and gawk

In This Appendix

• The basics for using sed
• What you need to know about gawk

If you do any type of data handling in your shell scripts, most likely you'll need to use either the sed or gawk programs (and sometimes both). This appendix provides a quick reference for sed and gawk commands that come in handy when working with data in your shell scripts.

The sed Editor

The sed editor can manipulate data in a data stream based on commands you either enter into the command line or store in a command text file. It reads one line of data at a time from the input and matches that data with the supplied editor commands, changes data in the stream as specified in the commands, and then outputs the new data to STDOUT.

Starting the sed Editor

The format for using the sed command is:

 sed options script file

The options parameters allow you to customize the behavior of the sed command and include the options shown in Table B.1.

Table B.1 The sed Command Options

Option	Description
-e script	Add commands specified in script to the commands run while processing the input.
-f file	Add the commands specified in the file file to the commands run while processing the input.
-n	Don't produce output for each command, but wait for the print command.

The script parameter specifies a single command to apply against the stream data. If more than one command is required, you must use either the -e option to specify them in the command line or the -f option ...