Comment # 5 on bug 1210121 from Kilian Hanich

Well, normally you can provide a shell with a script to execute by putting the
path to it as the first parameter.

I did this in my normal setup since I move the script in ExecStartPre to /tmp
and execute it from there so it can delete itself after it's done and you can't
execute something from /tmp directly because some other subsystem (I didn't
bother to investigate which one) blocks it. I also can't just execute the
script from /usr/local/sbin and then delete it directly since this causes it to
error out.