Helper script for deluge. hardlinks completed torrents into another folder (and unrars it, if appropriate)

torrent-complete.sh

#!/bin/bash

# Helper script for the Deluge torrent client
# Intended to be run at torrent completion, using the 'torrent complete' event in the 'Execute' plugin.
#
# The basic idea is to hardlink the files that deluge has just finished downloading to a second directory.
# This allows you to configure deluge to automatically pause or delete torrents when they reach a given seed ratio,
# while also keeping a copy around for other reasons. For example, SyncThing could be used to propagate new downloads
# to a remote machine to be processed further. When processing has finished, and the file is deleted/moved out of the
# Syncthing folder, the remote Syncthing will propagate a deletion back to the original Synchting (on the machine
# running deluge).
#
# The end result is that the lifetime of files involved both in deluge's seeding process and the 'forward to somewhere
# else' process (e.g. via Syncthing) are decoupled, and can safely execute in parallel without needing to be aware of
# what the other is doing. And yet the net result is that the files will still be cleaned up automagically when both
# have finished their respective tasks.
#
# Paul Chambers, Copyright (c) 2019.
#
# Made available under the Creative Commons 'BY' license
# https://creativecommons.org/licenses/by/4.0/
#

# set -x

torrentId=$1
torrentName=$2
torrentPath=$3

# echo "$torrentId $torrentName $torrentPath" >> /tmp/torrent-complete.log

srcDir="/home/user/files/downloads/seeding"
destDir="/home/user/files/downloads/complete"

label="${torrentPath#$srcDir}"

# note that srcPath may be a file, not necessarily a directory.
# Which means the same is true for destPath.
srcPath="${torrentPath}/${torrentName}"
destPath="${destDir}${label}/${torrentName}"

# echo "hardlink ${srcPath} to ${destPath}" >> /tmp/torrent-complete.log

if [ -d "${srcPath}" ]
then
    # srcPath is a directory, so make sure destPath exists and is a directory,
    # then recursively link the *contents* of the srcPath directory into destPath
    mkdir -p "${destPath}"
    cp -r "${srcPath}/"* "${destPath}"
else
    # srcPath is a file, so just link it
    cp "${srcPath}" "${destPath}"
fi

#
# if there are .rar files, unpack them
# usually there is only one, but nothing prevents more than one..
#

for rarFile in `find "${destPath}" -name "*.rar"`
do
    # echo "unrar ${rarFile}" >> /tmp/torrent-complete.log
    # if the unrar completes without error, unlink the .rar file and its companions.
    # the originals will live on in srcDir and continue to be seeded.
    cd "$(dirname ${rarFile})" \
    && unrar e -inul -o+ "${rarFile}" \
    && find . -type f \( -regex '.*\.r[0-9][0-9]' -o -name '*.rar' \) -delete
done

# could unpack other archives here too, but it's preferable to decompress
# any already-compressed archives at the remote machine, not here.