Chown and the risk of corrupting the backup disk

Question

I am about to modify the file ownership recursively in a filesystem that uses ACLs. Because it is my backup disk, I thought I'd solicit comments on the script before I run it.

#!/bin/bash
# Replace Foobar, Bob, and Brand.
PREFIX="/Volumes/Foobar-Time-Machine/Backups.backupdb/Bob’s MacBook"
SUFFIX="/Brand/Users/"
USER="bob"

for dir in "${PREFIX}"/*/
do
    chmod -R -a "group:everyone deny chown" "${PREFIX}${dir}${SUFFIX}${USER}"
    chown -R $USER "${PREFIX}${dir}${SUFFIX}${USER}"
    chmod -R =a# 1 "group:everyone deny add_file,delete,add_subdirectory,delete_child,writeattr,writeextattr,chown" "${PREFIX}${dir}${SUFFIX}${USER}"
done

Do you spot a disaster waiting to happen? The first chmod is meant to remove minimal ACL and the second is meant to restore it. Can the script be made safer? Needless to say, the script would be run as sudo.

Answer 1

I would use find with '-print0' and xargs... ACL are cryptic, better not to use them.