A script which removes torrents from transmission when they are completed and stopped. Developed for Synology DiskStation as a cron job.

cleanup-transmission-list.sh

#!/bin/sh

# Called with the credentials for the rpc-username and rpc-password:
# ./cleanup-transmission-list.sh username password

# Exit early if user and pass is not passed as arguments
if [ "$1" == "" ] || [ "$2" == "" ]; then
	exit 0;
fi

# Variables
USER=$1 # Param 1 (RPC Username)
PASS=$2 # Param 2 (RPC Password)
TRANSMISSION="/usr/local/transmission/bin/transmission-remote --auth "$USER":"$PASS

# Get a list of all current torrents ids.
TORRENTS=`$TRANSMISSION --list | sed -e '1d;$d;s/^ *//' | cut -s -d " " -f 1 | sed "s/[^0-9]//"`
# Loop through all torrents and remove them if they are completely finished
for TORRENT_ID in $TORRENTS
do
	# Check if torrent is completed
	IS_COMPLETED=`$TRANSMISSION --torrent $TORRENT_ID --info | grep "Percent Done: 100%"`
	# Check if torrent is stopped
	IS_STOPPED=`$TRANSMISSION --torrent $TORRENT_ID --info | grep "State: Stopped\|Finished\|Idle"`

	if [ "$IS_COMPLETED" != "" ] && [ "$IS_STOPPED" != "" ]; then			
		$TRANSMISSION --torrent $TORRENT_ID --remove
	fi
done