Using kid3-cli in a shell script

I have a mess of m4a files each of which contains a path to a caf file. I recently moved the caf files to a new HD and temporarily created a symlink to the old drive name. This allows the m4a files to find the caf files.

I would like to chenge the paths in the m4a files to the new drive. This only requires a simple change to one word -- /volumes/OldHD/etc. to /volumes/NewHD/etc. This requires changing the tag kid3 calls PPat. I can get kid3-cli sort of working in a shell script but I can't capture the output.

This works:

$kid <<! select "$f" get PPat !

where $kid is the location of kid3-cli and $f is the m4a file name, but it puts the output on the terminal.

Ideally I'd like to use something like this:

m=$kid <<! select "$f" get PPat !

but it doesn't work. I figured maybe I could get the output into a file and then read the file. I think this is supposed to work, according to the manual, but it doesn't.

$kid <<! select "$f" get PPat:'./foo' !

So, can anybody suggest a solution?

Imported from SourceForge, author: rbpeirce