Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Overview of this book

The shell remains one of the most powerful tools on a computer system — yet a large number of users are unaware of how much one can accomplish with it. Using a combination of simple commands, we will see how to solve complex problems in day to day computer usage.Linux Shell Scripting Cookbook, Second Edition will take you through useful real-world recipes designed to make your daily life easy when working with the shell. The book shows the reader how to effectively use the shell to accomplish complex tasks with ease.The book discusses basics of using the shell, general commands and proceeds to show the reader how to use them to perform complex tasks with ease.Starting with the basics of the shell, we will learn simple commands with their usages allowing us to perform operations on files of different kind. The book then proceeds to explain text processing, web interaction and concludes with backups, monitoring and other sysadmin tasks.Linux Shell Scripting Cookbook, Second Edition serves as an excellent guide to solving day to day problems using the shell and few powerful commands together to create solutions.
Table of Contents (16 chapters)
Linux Shell Scripting Cookbook
About the Authors
About the Reviewers

Using sed to perform text replacement

sed stands for stream editor. It is a very essential tool for text processing, and a marvelous utility to play around with regular expressions. A well-known usage of the sed command is for text replacement. This recipe will cover most of the frequently-used sed techniques.

How to do it…

sed can be used to replace occurrences of a string with another string in a given text.

  1. It can be matched using regular expressions.

    $ sed 's/pattern/replace_string/' file


    $ cat file | sed 's/pattern/replace_string/'

    This command reads from stdin.


    If you use the vi editor, you will notice that the command to replace the text is very similar to the one discussed here.

  2. By default, sed only prints the substituted text. To save the changes along with the substitutions to the same file, use the -i option. Most of the users follow multiple redirections to save the file after making a replacement as follows:

    $ sed 's/text/replace/' file >newfile
    $ mv newfile file