timer unit
also: systemd timer, .timer unit
A systemd unit file that defines a scheduled task or timer, specifying when and how often a service or script should run, similar to cron jobs but with more flexibility and integration with the init system.
A timer unit is a systemd configuration file (with a .timer extension) that schedules the execution of another unit—typically a .service unit—at specified times or intervals. Timer units replace or complement traditional cron jobs with better integration into the systemd ecosystem.
Timer units support both calendar-based scheduling (like "daily at 3 AM") and monotonic timers (like "5 minutes after boot" or "every 1 hour"). They are more flexible than cron and provide features such as automatic service restart on failure, detailed logging through journald, and easy enable/disable management.
Example: A timer unit backup.timer might be paired with backup.service and configured to run a backup script every night. You enable it with systemctl enable backup.timer and check its status with systemctl list-timers.