Rename music files with bad filenames (e.g. invalid encoding) with a "track description file" containing good filenames.

rename-tracks.sh

#!/bin/bash

# Usage:
# cat <file> | sh rename-tracks.sh
# Each line in <file> should be "<trackNo>.<trackName>"
# There must be an empty line at the end of file.

# Detect file extension.
if [ $(ls -1 *.mp3 2>/dev/null | wc -l) != 0 ]; then
  fileExt="mp3"
elif [ $(ls -1 *.flac 2>/dev/null | wc -l) != 0 ]; then
  fileExt="flac"
elif [ $(ls -1 *.wav 2>/dev/null | wc -l) != 0 ]; then
  fileExt="wav"
else
  fileExt="unknown"
fi

echo "Detected $fileExt"

# Rename files.
while IFS= read -r line
do
  trackNo="$(echo "$line" | cut -d. -f 1 -s)"
  trackName="$(echo "$line" | cut -d. -f 2- -s)"

  # Skip invalid trackNo and trackName.
  [ -z "$trackNo" ] && continue
  [ -z "$trackName" ] && continue

  mvSrc="$trackNo*"
  mvDest="$trackNo.$trackName.$fileExt"

  # Rename only when dest doesn't exist.
  if [ ! -f "$mvDest" ]; then
    echo "Rename $mvSrc to $mvDest"
    mv $mvSrc "$mvDest"
  fi
done