I have a folder full of .wav audio files.

Some are stereo, most are mono splits.

The mono split pairs are all named foo bar track.L.wav and foo bar track.R.wav

I can use the command line tool sox to combine a mono pair into 1 stereo track like this:

sox -M track1.L.wav track1.R.wav track1.Stereo.wav

where the first 2 files are the mono pairs, and the third is the output stereo file.

This is great, but I'd like to have a script that will automatically find all the mono pairs and combine them into stereo files.

I.e., I need it to find all files which have the same name except for the .L. and .R. before the extension, and run sox on them, outputting to a new file with the same name without the L/R suffix.

For example, if my folder contains these files:

track1.L.wav
track2.L.wav
track3.L.wav
track4.L.wav
track1.R.wav
track2.R.wav
track3.R.wav
track4.R.wav
track6.wav
track7.wav

I need to run these commands:

sox -M track1.L.wav track1.R.wav track1.Stereo.wav
sox -M track2.L.wav track2.R.wav track2.Stereo.wav
sox -M track3.L.wav track3.R.wav track3.Stereo.wav
sox -M track4.L.wav track4.R.wav track4.Stereo.wav

Here's where I am so far:

for file in ./*.L.wav;
do 
    file2=`echo $file | sed 's_\(.*\).L.wav_\1.R.wav_'`;
    out=`echo $file | sed 's_\(.*\).L.wav_\1.STEREO.wav_'`;
    echo $file - $file2 - $out;
done

That works, but when I replace the echo line with

sox -M $file $file2 $out;

it doesn't work; spaces in the filenames cause it to fail.