[Tutor] systemd

[Dave Hill]

Hi,

I am nearly ready for the new season on the Heritage railway I volunteer 
on and I am putting the final touches to a revamped 'runaway train' 
attraction in the museum. The last act is to get the code to auto-start 
on power up, and I thought that I would use 'systemd'.

The code runs on a Raspberry Pi;

    via the GPIO: sensing an input, reed switch, and controlling three
    outputs; smoke machine, fan and vibrating floor.

    on activation a video is played, at 8 times real speed, which is
    viewed through a mock-up of a loco cab.

I can run a program using:

    [Unit]
    Description=TestVideo Service
    After=multi-user.target

    [Service]
    Type=idle

    User=pi
    ExecStart=/bin/bash /home/pi/Code/testVideo.sh

    Restart=no
    RestartSec=0

    [Install]
    WantedBy=multi-user.target

where 'testVideo.sh'

    ## Dave Hill, 28/02/2019

    # 2 = HDMI, 1 = headphones, 0 = Auto
    amixer cset numid=3 1

    python3 /home/pi/Code/TestVideo#6.py CLIP0026.MP4 20 DEBUG

    exit 0

as I want to control the audio output, in this case direct audio to the 
Raspberry Pi stereo output.

The program runs an infinite loop that can be exited by Cntrl-C

I would like to take advantage of the 'restart' functionality, but I 
still wish to have a method of exiting

    i.e. Restart=always

Is there a way in which I can have automatic restart but also have a way 
of exiting?

Thanks in advance,

Dave