Recurring jobs¶

Recurring jobs can be configured with systemd or cron. On managed Linux workstations you have the option to use systemd timers, which are described here. Cronjobs are a thing of the past and not suitable for modern multi-user systems.

Run a script every hour¶

Let's create a systemd timer that will run an existing executable script ~/bin/foo.sh every hour.

Create the service unit¶

systemctl --user edit --full --force foo.service

This opens the editor, paste the following or similar content:

[Unit]
Description=Run foo
After=network-online.target

[Service]
Type=oneshot
ExecStart=%h/bin/foo.sh

[Install]
WantedBy=multi-user.target

Notes: The placeholder %h will be expanded to your home directory path. You may also specify an absolute path.

You can test (start) the service unit using:

systemctl --user start foo.service
systemctl --user status foo.service

Create the timer unit¶

systemctl --user edit --full --force foo.timer

With the following content:

[Unit]
Description=Run foo hourly
After=network-online.target
ConditionHost=|<hostname>

[Timer]
OnCalendar=hourly

[Install]
WantedBy=timers.target

Replace <hostname> with the hostname of the computer. You may also specify ConditionHost multiple times to configure the timer on multiple hosts.

You can test or start the timer unit using:

systemctl --user start foo.timer
systemctl --user status foo.timer

Enable the timer unit to activate on boot¶

To automatically start the timer after reboot:

systemctl --user enable foo.timer
loginctl enable-linger

Note: You need to configure loginctl enable-linger on all computers where the timer should automatically start after a reboot. This will make sure the systemd user service manager will start for your user without you having to manually log in.

Listing or removing timers¶

Show active timers:

systemctl --user list-timers

Show all timers:

systemctl --user list-timers --all

Disable and stop timer:

systemctl --user stop foo.timer
systemctl --user disable foo.timer

Manual configuration and logs¶

Systemd user units are stored in your home directory in ~/.config/systemd/user and are available on all managed Linux workstations via NFS.

The timer and service configured above will look like this:

+rdatest@krum:~$ tree .config/systemd/
.config/systemd/
└── user
    ├── foo.service
    ├── foo.timer
    └── timers.target.wants
        └── foo.timer -> /home/rdatest/.config/systemd/user/foo.timer

Whenever you manually edit those files, you need to reload systemd:

systemctl --user daemon-reload

To inspect the log:

journalctl --user -f

Run a script immediately after boot¶

To automatically start a long running job once after the computer boots up create and configure systemd service and timer units as shown above.

But use the following timer section in the timer unit instead of OnCalendar:

[Timer]
OnBootSec=10

This will start the timer 10 seconds after boot.

Documentation¶

Please refer to the manpages man 5 systemd.timer and man 7 systemd.time for details.