1.9 KiB
Systemd Timers
Gen Z's crontab
Generally there are 3 pieces to a timer
- The script being run
- The systemd service defining which script to run
- The systemd timer triggering the service
Tools
systemd-analyze calendar can be very handy at verifying timestamps
systemd-analyze calendar *-*-* *:10,20:10
Time is in the format:
DayOfWeek Year-Month-Day Hour:Minute:Second
Fri *-*-* 00/1:00:00 # Every hour on fridays
*-*-* 2:15,45:0/3 # At 2am, fire it on ever third second at 15 and 45mins
To find suitable targets for things like Wants and After, see
systemd.special(7). If you want to check the current status of your targets,
use:
systemctl list-units --type target --state active
systemctl status network-online.target
Placing files
Scripts should be put in /usr/local/bin if they can be run by anyone or
/usr/local/sbin if they should only be run by root
Define a xxx.service file in /etc/systemd/system. Set the timer as one of
its Wants. network.target may be more appropriate in some cases. Do not add
an [Install] section, as your timer already handles that
[Unit]
Description = Sends current ip address to uni servers
Wants = broadcast_ip.timer
Wants = network.target
After = network.target
[Service]
Type = oneshot
ExecStart = /usr/local/bin/broadcast_ip.sh
Now you'll need a timer file. It's easiest to make it have the same name as the
service file and put it in the same /etc/systemd/system
[Unit]
Description = Sends current ip address to uni servers
[Timer]
Unit = broadcast_ip.service
OnCalendar = *-*-* *:15,45:00
[Install]
WantedBy = timers.target
To make sure your unit doesn't always fire on boot, remove the [Install] from
the service and don't put a Requires line in the timer