Compare 2 folders and write the differences to a file (without opening a window).
Compare 2 folders and write the results to this pathname. The file is always created even if there are no changes to report.
When diffing folders to a file, DiffMerge sets the exit status to:
0: IDENTICAL - the 2 folders are identical.
1: DIFFERENT - there are changes to report.
2: FILE-ERROR - there were filesystem errors that prevented the folders from being compared.
3: SYNTAX-ERROR - there were syntax errors with the command line arguments.