Hello,
I'm using both Plex and Transmission and currently trying to trigger a script when Transmission is done downloading a torrent.
I changed these settings while transmission was stopped :
Your script is using programs that are not in its PATH, it doesn't find them.
You should either define PATH at the top of the script, or use the full path of the program(s).
BTW Plex doesn't need anything to work, as long as you have your (whole) configuration right (i.e. Transmission moves the finished download into Plex's library, and Plex has autoupdate set on that library -- but Plex has/had a bug where setting "run a partial scan when changes are detected" didn't work, and prevented the automatic update, the solution was to not set the partial scan, the automatic scan has always worked fine but it does need the intended optimization of the partial scan).