A Sonarr post processing script to turn copied torrent imports into symlinks, strongly encourage hard link setup instead.

sonarr_symlink_torrent.sh

#!/bin/bash
sonarr_label="tv"

# Make sure we're working on torrents.
if ! [[ "${sonarr_episodefile_sourcepath}" =~ torrent ]]; then
  echo "[Torrent Symlink] Path ${sonarr_episodefile_sourcepath} does not contain \"torrent\", exiting."
  exit
fi

# If the source file doesn't exist, error out.
if ! [[ -f "${sonarr_episodefile_sourcepath}" ]]; then
  echo "[Torrent Symlink] File ${sonarr_episodefile_sourcepath} does not exist, exiting."
  exit 1
fi

# If it isn't a single file, it might be a packed release which should be skipped.
base_dir=$( basename "${sonarr_episodefile_sourcefolder}" )
if [[ "${base_dir}" != "${sonarr_label}" ]] && find "${sonarr_episodefile_sourcefolder}" -iregex '.*\.r[0-9a][0-9r]$' | grep -Eq '.*'; then
  echo "[Torrent Symlink] Found rar or r00 files, skipping symlink creation."
  exit
fi

# Make sure the copy is done by comparing source and destination file sizes.
orig_file_size=$(stat -c%s "${sonarr_episodefile_sourcepath}")
dest_file_size=$(stat -c%s "${sonarr_episodefile_path}")

# Make the actual symlink.
if [[ ${dest_file_size} == "${orig_file_size}" ]]; then
  echo -n "[Torrent Symlink] Switching ${sonarr_episodefile_sourcepath} to symlink pointed at ${sonarr_episodefile_path}... "
  if rm "${sonarr_episodefile_sourcepath}" && ln -s "${sonarr_episodefile_path}" "${sonarr_episodefile_sourcepath}"; then
    echo "done."
  else
    echo "failed."
  fi
else
  echo "[Torrent Symlink] Size of ${sonarr_episodefile_sourcepath} and ${sonarr_episodefile_path} differ, skipping."
fi

If I knew python, I'd have done it in python. Why don't you have a go at it?