I have several thousand files to test before/after synchronization, and I want to be very sure they're identical.

I can't come up with anything more efficient than the attached.

@jpmens shouldn't rsync's --checksum provide this functionality?

@jpmens what does "identical" mean exactly? Right now you only check that "all files in the first set have the same checksum in the second set". Not metadata (timestamps), permissions, or the presence of additional files in the second set. If that's sufficient, I think you're good.

@jpmens you could use fpart and gnu parallel, but yes.

@eliasp it does; I'm just in paranoid mode and want an additional point of view.

@zhenech good catch, but indeed permissions and additional files are ok here. I just want to ensure content of existing is equal

@isotopp fpart was new to me, thanks. A bit much now, but good to know.

@jpmens https://blog.koehntopp.info/2019/11/11/filling-disk-space-fast.html

It is useful to get fluent with it, because fpart + parallel = easy parallel action in shell with many files.

@jpmens @zhenech what if the second set has more files ?

@letoams it doesn't.

@zhenech

@jpmens if it’s on *BSD or macOS mtree(8) can do that