[Unit]
Description=Run snap-sync cleanup
Requires=run-media-user-usbdrive.mount
After=run-media-user-usbdrive.mount snap-sync.service

[Service]
Environment=TZ=UTC
Type=oneshot
ExecStart=/run/media/user/usbdrive/snapshots/scripts/clean-snap-sync-external.sh

[Install]
WantedBy=snap-sync.service