Unison

A quest for cross-platform (linux,win32) bidrectional remote syncronization found itself mired in cygwin+rsync, with no light at the end of the tunnel. I was having seemingly-random inexplicable hangs of rsync. (Which is -vvvvv showed nothing, and it hung instead of exit()ing, after finishing everything else correctly.) And rsync still didn’t do bidirectional sync, I’d need to run it twice, one in each direction.

A quick google for “bidirectional rsync” turned up Unison, which promises to do all these things and more!