Create symlinks in time machine backup?

Question

I have a time machine backup /Volumes/MyTimeMachine/Backups.backupdb/MyMachine. Exactly as Apple creates a Latest symlink pointing toward the latest snapshot, I would like to create symlinks toward other snapshots. But I get permission denied when I do, in terminal,

% cd /Volumes/MyTimeMachine/Backups.backupdb/MyMachine
% ln -s 2018-06-11-xxxx my_link

where 2018-06-11-xxxx would be one of the snapshot. I even get permission denied with sudo!! Is there something wrong with my Time Machine disk or is that normal on MacOS High Sierra?

Answer 1

There are access control lists in addition to the typical permissions that lock you out of the time machine destination and prevent this. You might succeed in disabling that when Time Machine isn't looking, but when it starts up, it will likely notice you messed with the files it wrote and mark that destination as read only and never back up again to that destination.

You'd then need to retire it to a shelf or erase the drive and let Time Machine exert total control over a blank folder and start over with backups.

That being said, you can do this by maintaining your folder where you create the links outside the /Backups.backupdb folder (my best suggestion) or changing ACL and removing the restrictions Apple puts there.

Here are a couple related articles on the chmod to mess with the ACL lists - you might need a general article as well if you've not listed / modified / added / removed ACL on macOS - that's quite an article in and of itself that I'll leave for another question to answer.

• How to remove my local Backupdb.backupsdb?
• How do I change the ownership of files backed up with Time Machine
• Time Machine and the dreaded negative sign (this is what happens when Time Machine detects a modification of permissions or content - the prohibitory sign and the "you need to start over" message)
• Can't chmod or chown a file in TimeMachine backup directory
• Moving Time Machine backup between two local disks results in full backup instead of incremental (pain experienced even trying to move the whole folder "intact")