1 Add --include option (opposite of --exclude).
3 Look into sdiff improvement here:
4 http://www.pkix.net/~chuck/sdiff2.diff
6 Propagate stderr from subprocess so that diff3 does
7 a better job of explaining _why_:
8 > $ diff3 /bin/sh /bin/false /bin/mv
9 > diff3: subsidiary program 'diff' failed (exit status 2)