I have a process that create directories and files inside a working directory, ex: /workingdir/file1 /workingdir/file2 /workingdir/dir1/file1 /workingdir/dir1/dir2/file1 /workingdir/dir1/file2 I need to avoid deletion/overwrites of created folders/files for that user, but allow subsequent folders/subfolders/files creation. I try permissions, gid, acl with no luck. What is the correct way to do that ? (i can use a cron job if needed)