A team want to implement a crude file dump backup solution to be used by multiple hosts. They have a remote user on the backup server backupusr that they can SSH/SCP with, with SSH keys setup.The directory hierarchy on the backup server is:  -/data/  -backups/    -host1/    -host2/    -host3/    ...I would like the backup user to be able to write files into a host directory but not delete files once they are written.Is there any way of doing this without using xattrs to set to immutable?I can't get either setgid or a default ACL/mask working because once a file is copied in it is owned by backupusr which can always delete its files.So I'm probably looking at a way to change owner and then I could use the stickybit.Any suggestions?
scp file to remote server prevent delete
permissions;acl;chown;setgid;sticky bit