I also needed a date-modified mode for rsync, so I don't think you missed something there.

I was downloading ISO files into various subdirectories of /home/me/isos and wanted to rsync occasionally, but didn't want to waste time on dirs I already had done.

I wrote a script that "touch"ed a file when it exited, to set the date it was last run. I don't have the code handy, but it went like:

$f = `find /home/me/isos -type f -iname '*iso' `;
@imlist = split(/\n/,$f);
$touchtime = -M ".touch_sem";
for $image (@imlist) {
  if ($touchtime <= -M "$image") { #rsync }
}
`touch .touch_sem `;
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