Master Linux Regular Expressions: Essential Metacharacters and Practical Examples

Regular expressions are character patterns used to match specific strings during search operations.

In Linux, metacharacters are divided into two categories:

Shell metacharacters, interpreted by the Linux shell.

Regex metacharacters, interpreted by tools such as vi, grep, sed, and awk.

Before using the examples, configure grep to highlight matches by adding the --color option.

Create a test file named re-file with the following content:

Regular Expression Metacharacters

Special Metacharacters

Extended Regular Expressions

Practical Exercises

Match all lines that start with love.

Match all lines that end with love.

Match lines starting with l, followed by any two characters, and ending with e.

Match zero or more blank lines followed by the string love.

Match love or Love.

Match any uppercase letter A-Z followed by ove.

Match any line containing characters not in the range A-Z (i.e., all lowercase characters).

Match the literal string love..

Match a space character.

Match any character.

Match the character o repeated 2 to 4 times.

Match the character o at least 2 times.

Match the character 0 at most 2 times.

Match the previous character one or more times.

Match zero or one occurrence of a character.

Match any of multiple strings (alternation).

Group filtering and matching.

Author: ansheng Source: https://blog.ansheng.me/article/examples-of-linux-regular-expressions