How to get script to 'always launch' on device connect?

Question

I'm trying to run a script when a device is connected. My udev and systemd files are loaded and triggered, but will only launch the script a single time. If I disconnect and reconnect the device, the script no longer launches. I have found that reloading systemctl at the end of my script will fix this issue (this method only works for 'user' systemd services). In previous version of Ubuntu, I was able to simply use udev with systemd, and it worked every time. It also didn't matter if I used either 'user' or 'system' service files. They both worked, which also allowed me to run commands as root.

I don't believe my script is the issue, as a simple file launch or notify-send command will only work after reloading systemctl (or if I reboot).

How can I use systemd where I don't have to constantly reload systemctl for it to work? Also if possible, how can I regain the systemd/system usage so I can run scripts as root?

Edit: I am using the desktop version of Ubuntu 20.04.

I have used the command systemctl status and it showed that I had a failed service (wasn't my custom service file). I disabled the service and reloaded. No more failed services, but my original problem persists.

Answer 1

Answer by OP, removed from the question:

Fixed: I added ENV{SYSTEMD_USER_WANTS}+="myfile.service" into my udev file, and it appears to have fixed the issue. Thanks bac0n for the suggestion.

Also, thanks to everyone else who volunteered their time.

My udev entry:

ACTION=="add", ATTRS{product}=="DTK-2100", ATTRS{idProduct}=="00cc", ATTRS{idVendor}=="056a", TAG+="systemd"

my systemd entry:

[Service]
Type=forking
Restart=no
ExecStart=/home/anon/xsetwacom.sh

[Install]
WantedBy=default.target
WantedBy=sys-devices-pci0000:00-0000:00:1a.2-usb5-5\x2d1-5\x2d1:1.0.device