Book Image

Linux Shell Scripting Essentials

By : Sinny Kumari, Khem Raj
Book Image

Linux Shell Scripting Essentials

By: Sinny Kumari, Khem Raj

Overview of this book

Table of Contents (15 chapters)
Linux Shell Scripting Essentials
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Regular expressions


Regular expression (also known as regex or regexp) provides a way of specifying a pattern to be matched in a given big chunk of text data. It supports a set of characters to specify the pattern. It is widely used for a text search and string manipulation. A lot of shell commands provide an option to specify regex such as grep, sed, find, and so on.

The regular expression concept is also used in other programming languages such as C++, Python, Java, Perl, and so on. Libraries are available in different languages to support regular expression's features.

Regular expression metacharacters

The metacharacters used in regular expressions are explained in the following table:

Metacharacters

Description

* (Asterisk)

This matches zero or more occurrences of the previous character

+ (Plus)

This matches one or more occurrences of the previous character

?

This matches zero or one occurrence of the previous element

. (Dot)

This matches any one character

^

This matches the...