GITFOLDER="/srv/some/folder" ls-files --others --exclude-standard | tar czf ${GITFOLDER}-archives/uploads-$(date '+%Y%m%d%H%M').tar.gz -T -
Assuming your web app has a git checkout is in /srv/some/folder (i.e. there is a /srv/some/folder/.git), archive the user uploads to /srv/some/folder-archives with that one liner.
Use:
cd /srv/some/folder
# this one-liner
A fully complete script would:
$GITFOLDER exists$GITFOLDER has a .git directorytmp=$(mktemp)) file to log anything; if [ "$?" -ne 0 ] ; exit with status exit 1, otherwise delete the $tmp file and exit 0.