Diff'ing between MS-DOS (FAT32) and Mac OS Extended (Journaled) Volumes
When I ran the command
diff -qr dirA dirB | sort > diffs.txt
I received a lot of notifications that the "._filename.extension" were different on the one volume but not the other. What had happened is that that volume is formatted as MS-DOS (FAT32) and the other is as Mac OS Extended (Journaled).
When I grep'ed through the diffs.txt file, I used the two flags as suggested above but this time removing any of those files that had the ._ in them
grep -v -e '._' diffs.txt
or
grep -v -e ': .' diffs.txt // since the format was "full_path: filename"
... that showed me the real differences between the directories.
Thanks!