How to Set Up Systemd Timers

Prerequisites

Before setting up timers, make sure you have:

• SSH access to your VPS
• Root or sudo privileges

Step 1: Create a Service File (The Task to Run)

Connect to your VPS:

ssh hxroot@YOUR_SERVER_IP -p 22

sudo nano /etc/systemd/system/backup-task.service

Add:

[Unit]
Description=Daily Backup Service

[Service]
Type=oneshot
ExecStart=/usr/local/bin/backup.sh
User=root
StandardOutput=journal

Type=oneshot indicates the service runs once and exits.

Step 2: Create a Timer File (When to Run)

sudo nano /etc/systemd/system/backup-task.timer

Add:

[Unit]
Description=Run backup daily at 2:00 AM

[Timer]
OnCalendar=daily
Persistent=true

[Install]
WantedBy=timers.target

Step 3: Enable and Start the Timer

sudo systemctl daemon-reload
sudo systemctl enable backup-task.timer
sudo systemctl start backup-task.timer

Step 4: Verify Timer Status

sudo systemctl list-timers backup-task.timer

Example output:

NEXT                         LEFT       LAST                         PASSED    UNIT                ACTIVATES
Tue 2026-04-30 02:00:00 UTC  16h left   Mon 2026-04-29 02:00:00 UTC  10h ago   backup-task.timer   backup-task.service

Common OnCalendar Expressions

• hourly – Run every hour at minute 0
• daily – Run daily at 00:00:00
• weekly – Run weekly on Monday at 00:00:00
• monthly – Run on first day of month at 00:00:00
• *-*-* 02:00:00 – Every day at 2 AM
• Mon..Fri 09:00:00 – Weekdays at 9 AM
• Sun 03:00:00 – Sundays at 3 AM
• *-*-01 00:00:00 – First day of each month

Advanced Timer Options

[Timer]
OnBootSec=10min
OnUnitActiveSec=24h
RandomizedDelaySec=5min
AccuracySec=1h

• OnBootSec – Run after boot
• OnUnitActiveSec – Run time after last activation
• RandomizedDelaySec – Adds random delay to prevent thundering herd
• AccuracySec – Allowed scheduling inaccuracy (for efficiency)

Test Timer Without Waiting

sudo systemctl start backup-task.service

Manually runs the service to test.

Disable a Timer

sudo systemctl disable backup-task.timer
sudo systemctl stop backup-task.timer

View All Timers

systemctl list-timers --all

Check Timer Logs

journalctl -u backup-task.service