20 Essential Shell Functions to Supercharge Your Scripts

In shell scripts you can define various functions to perform different tasks. Below are 20 commonly used custom functions covering file operations, text processing, system monitoring, and more.

Check if a file exists

Check if a directory exists

Get file size

List all files in a directory

Check if a command exists

Get current date

Get current time

Calculate difference between two dates

Print colored text

Delay execution

Check if running as root

Get IP address

Generate a random string

Check if a port is open

Restart a service

Check service status

Get the most recently modified file

Count files in a directory

Empty a file's content

Send an email

Note that some functions may need adjustments for your environment; for example, the email function relies on the mail command and the service functions require systemctl on systemd‑based systems.