What is crontab and what is it used for?

Crontab is a utility in Unix-like systems for scheduling the execution of tasks (scripts, commands) according to a timetable. It allows automatic execution of commands at specified times, for example, daily at midnight or every Friday at 15:00.

The crontab file contains a list of tasks with specified times and commands. An example entry in crontab:

# Run the backup.sh script every day at 2:30 AM
30 2 * * * /home/user/backup.sh

It is used for automating routine tasks: backups, data updates, report sending, etc.