for /F "delims=" %i IN ('dir /s /b *.flac') DO @flac -t "%i" 2>> flactest.txt
Above will test all flac files in a directory and all subdirectories and save the test output to the "flactest.txt" file
find "ERROR" "flactest.txt" > flacerrors.txt
Above will scan the flactest.txt file and present an errors file