rsync a directory tree with optional overlay tree

Question

I maintain a directory structure containing dirs and files that I regularly push to ~50 hosts, which are divided into 3 groups that have slightly different needs - minor mods in a couple of files.

So ideally I would have 4 directories:

/path/to/sync/common/   <- common files
/path/to/sync/group1/   <- group1 specific only
/path/to/sync/group2/   <- group2 specific only
/path/to/sync/group3/   <- group3 specific only

Then I'd run an rsync like

rsync -av --overlay /path/to/sync/groupN /path/to/sync/common remotehost:

Thinking in terms of a list of files to be transferred, I would like:

• anything present in common/ added to the file list; then
• anything present in groupN/ added to the list, clobbering anything already there

I realise I could populate the list myself and use --files-from=<LIST> but I would rather have rsync work it out if possible. I can't think of a simple way to populate the list myself that isn't clunky (second prize for pointing one out!)

Answer 1

I've figured out a way to do this that will work, by merging the trees locally first.

TEMPDIR=$(mktemp -d)
cp -r /path/to/sync/common/* $TEMPDIR
cp -r -f /path/to/sync/groupN/* $TEMPDIR
rsync -av $TEMPDIR/* remotehost:
rm -r $TEMPDIR

I'd still prefer to do it with rsync though, to say on local cp'ing.