Can I use rsync to capture diffs from multiple systems against a baseline? -

i've got event coming have many students using laptops work. of systems duplicated baseline image. i'm trying capture data has been changed/modified on systems during event. first thought put timestamp file in baseline image , use 'find --newer timestampfile' generate list of files have changed since baseline created , up. occurred me rsync might able using --backup , --backup-dir options. it's perfect, except 1 thing. also, work based on checksums rather timestamp.

in testing set test filesystems on local disk simulate actions. if run like:

rsync -cavhp --fake-super --backup --backup-dir=/backup/host1-backup host1-fs baseline-fs

it works fine , difference baseline first host directory, subsequent host directories don't work correctly. it's if using checkpoint set first sync.

is there way tell rsync not update in baseline directory can rsync changes multiple target hosts against base?

thanks, -d

some more time rsync , i've figured out solution here, figured i'd share. --compare-dest option trick.

first, create baseline comparison:

rsync -ave "ssh -i ~/.ssh/id_rsa" /local/path user@backuphost:/path/to/baseline

then, on each host want capture changes from:

rsync -ave "ssh -i ~/.ssh/id_rsa" --compare-dest=/path/to/baseline /local/path user@backuphost:/path/to/differential/backup

it's important note path passed --compare-dest path on remote host. have omit user@backuphost there.

-d