Task Scheduling

Task scheduling runs commands later, repeatedly, or at boot.

Overview

• systemd timers are the native option on modern Linux systems
• cron is a simple, time-based scheduler that remains widely used

Reference

systemd timers

• A timer unit usually has a matching service unit
• OnBootSec runs once after boot
• OnUnitActiveSec repeats after the previous run
• Reload unit files with systemctl daemon-reload

[Unit]
Description=My Timer

[Timer]
OnBootSec=3min
OnUnitActiveSec=1hour

[Install]
WantedBy=timers.target

[Unit]
Description=My Service

[Service]
ExecStart=/full/path/to/my/script.sh

[Install]
WantedBy=multi-user.target

Cron

0 */6 * * * /path/to/update_software.sh
0 0 1 * * /path/to/scripts/run_scripts.sh
0 0 * * 0 /path/to/scripts/clean_database.sh
0 0 * * 7 /path/to/scripts/backup.sh

Mental Model

• Use timers when you want native systemd integration
• Use cron when you want compact recurring schedules
• Prefer the simplest scheduler that fits the job