[X-Unix] Finder FUBARs another 'move'

[TjL]

I'm so sick and tired of Finder.

It seems like every single time I try a long move process via Finder,
especially when dealing with external hard drives.

I usually end up coming back later and find some excuse about
permissions or whatnot.  Normally completely useless error messages.

I've got partially moved folders (normally part of the 'copy' part
works but it never gets to the delete part) that I want to
consolidate.

So I'm thinking of making a shell script that will:

1) compare two folders

2) move files from SOURCE to TARGET which don't exist on TARGET

3) compare files which exist on both.
3a) If identical, delete the copy from SOURCE.
3b) If not identical, move from SOURCE to TARGET


But then I thought "I wonder if I'm reinventing the wheel?"

Any ideas?  Where should I be looking?

TjL