JACK Projects as System Services
In some applications, like headless or embedded systems, it can be helpful to autostart the jack server, followed by additional programs for sound processing. In this way, a system can boot into the desired configuration without additional user interaction.
There are several ways of achieving this. The following example uses systemd services for a user named student.
The JACK Service
The JACK service needs to be started before the
clients. It is a system service and needs just a few
entries. This is a minimal example - depending on the application and hardware settings,
the arguments after ExecStart=/usr/bin/jackd need to be adjusted.
[Unit] Description=Jack audio server [Install] WantedBy=multi-user.target [Service] Type=simple PrivateTmp=true Environment="JACK_NO_AUDIO_RESERVATION=1" ExecStart=/usr/bin/jackd -d alsa User=student
The above content needs to be placed in the following file (root privileges are required for doing that):
Afterwards, the service can be started and stopped via the command line:
In order to start the service on every boot, it needs to be enabled:
If desired, the service can also be deactivated:
The Client Service(s)
Once the JACK service is enabled,
client software can be started.
A second service is created, which
is executed after the JACK service.
This is ensured by the additional
entries in the [Unit] section.
The example service launches a Puredata
patch without GUI:
[Unit] Description=Synthesis Software After=jack.service Requires=jack.service [Install] WantedBy=multi-user.target [Service] Type=idle PrivateTmp=true ExecStartPre=/bin/sleep 1 ExecStart=/usr/bin/puredata -nogui -jack ~/PD/test.pd User=student
The above content needs to be placed in the following file:
The service can now be controlled with the above introduced
systemctl commands. When enabled, it starts on every boot
after the JACK server has been started: