Automatic start by using systemd

The shell script for startup of the control application (/usr/local/bin/aquarium_control_startup) has the following content:

echo 0 > /var/local/aquarium-ctrl.pid

touch /dev/mqueue/aquarium_control.6UXp

chmod o+rwx /dev/mqueue/aquarium_control.6UXp

/usr/local/bin/aquarium_control > /dev/null&

It resets any PID in the lock file from previously instances which were potentially not shut down correctly (for example, in case of power failure). It creates the message queue file which is not a file on the hard drive and sets permission accordingly. Finally, it starts the control application in the background.

The content of systemd unit file /lib/systemd/system/aquarium_control.service as following:

[Unit]

Description=Aquarium Control Application

After=multi-user.target


[Service]

Type=forking

ExecStart=bash /usr/local/bin/aquarium_control_startup


[Install]

WantedBy=multi-user.target

Upon creation/modification of the unit file, one must run the command sudo systemctl daemon-reload in order to activate the changes.

For starting the control application manually via systemd, one can use the command sudo systemctl start aquarium_control_startup.sh.

Creating message queues for operation or test of aquarium_control

sudo touch /dev/mqueue/aquarium_control.5UXp

sudo chmod o+rwx /dev/mqueue/aquarium_control.5UXp

sudo touch /dev/mqueue/aquarium_control.4UXp

sudo chmod o+rwx /dev/mqueue/aquarium_control.4UXp

sudo touch /dev/mqueue/aquarium_control.6UXp

sudo chmod o+rwx /dev/mqueue/aquarium_control.6UXp

sudo touch /dev/mqueue/aquarium_control.7UXp

sudo chmod o+rwx /dev/mqueue/aquarium_control.7UXp

sudo touch /dev/mqueue/aquarium_control.8UXp

sudo chmod o+rwx /dev/mqueue/aquarium_control.8UXp

sudo touch /dev/mqueue/aquarium_control.9UXp

sudo chmod o+rwx /dev/mqueue/aquarium_control.9UXp

Only one of the message queues is required for operating the control application. The other message queues are use for parallel SW unit testing.

initialize lock file with zero as PID

sudo echo 0 > /var/local/aquarium-ctrl.pid

The lock file has to be initialised to zero upon restart of the server. A missing or empty lock file is interpreted by the control application that something has gone wrong and startup will be aborted. In case of uncontrolled shutdown (e.g. power failure), the PID of the last operation may still be in the lock file, hence a reset to zero is required for this case.

start the application to run in the background

/usr/local/bin/aquarium_control > /dev/null&