Master Linux Regular Expressions: Essential Metacharacters & Practical Examples

Regular expressions are character patterns used to match specific characters during a search.

In Linux, metacharacters are generally divided into two categories:

Shell metacharacters, parsed by the Linux shell.

Regular‑expression metacharacters, parsed by text‑processing tools such as vi, grep, sed, and awk.

Before using regular expressions with grep, set the --color option so that matched strings are highlighted.

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

File content excerpted from < >

Regular Expression Metacharacters

Special metacharacters

Extended regular expressions

Practical Examples

Match all lines that start with love

Match all lines that end with love

Match lines that start with l , have any two characters in the middle, and end 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 character 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 (preceding character repeated)

Match the character o repeated 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 multiple strings using alternation (OR)

Group filtering and matching

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