Why doesn't this for loop work?

Solution 1:

The double quotes around the $(find ...) command make for see find's output as one single filename, which obviously is not what you want.

There are several ways to achieve what you want:

• Make find execute ffmpeg directly (no piping, no loops):

  find . -type f -name *.flac -exec bash -c '
     ffmpeg -i "$0" -c:a libmp3lame -q:a 2 "${0/%flac/mp3}"
  ' {} \;
  

• Use find ... -print0 | xargs -0 ... instead of for, which is specifically made for these purposes:

  find . -type f -name *.flac -print0 | xargs -0 -I {} bash -c '
      ffmpeg -i "$0" -c:a libmp3lame -q:a 2 "${0/%flac/mp3}"
  ' {}
  

• Change IFS to newline only, the use the same command as before, minus the double quotes:

  IFS=$'\n'
  for f in $(find . -type f -name *.flac); do
      ffmpeg -i "$f" -c:a libmp3lame -q:a 2 "${f/%flac/mp3}"
  done
  unset IFS
  

  The command unset IFS changes the IFS back to it's default value (not needed inside a shell script, unless it interferes with subsequent commands).

Solution 2:

Please read BashFAQ/020 - Greg's Wiki. To properly iterate over the output of find, here's a method that should cope with all sorts of strange characters in filenames (spaces, newlines, globbing, etc.)

while IFS= read -r -d '' file; do
   ffmpeg -i "$f" -c:a libmp3lame -q:a 2 "${f/%flac/mp3}"
done < <(find . -type f -name "*.flac" -print0)

Don't forget to quote "*.flac" to prevent expansion if there are files in the current directory ending with .flac.