Instead of letting Time Machine run automatically I use a shell script and the tmutil startbackup command to trigger backups, which gives me a much greater degree of flexibility. Specifically it lets me perform hourly backups to a local drive during my normal hours, with a separate network backup at night (since it tends to be a lot slower).

Unfortunately, I've discovered today that if the network drive is filling up enough that old backups need to be deleted, then the dialogue informing me of this will prevent the backup from proceeding until I hit okay, but since it occurs after I normally leave my computer my machine just ends up staying awake all night waiting for me to do something about it.

What I'd like to do is suppress this dialogue for my overnight backup, but leave it them enabled/re-enable it for my hourly backups. Is there a way I could do this? There doesn't appear to be any capability in tmutil itself. Is there a defaults option I could change perhaps?

  • Have you looked into AppleScript? You can run it through the command line. – At0mic Sep 18 '16 at 23:04
  • @IronCraftMan Can Applescript suppress these dialogues? – Haravikk Sep 19 '16 at 10:39
  • You are talking about the dialog that appears because of the “Notify after old backups are deleted” option in the Time Machine preferences? Are you sure that dialog prevents the backup from proceeding? I always thought the dialog didn’t appear until after the new backup has already been made. See my answer on how to temporarily turn off the option through defaults if you still need to do that though. – Rinzwind Oct 1 '16 at 9:15
  • Buy a bigger drive ;) – CousinCocaine Oct 1 '16 at 19:35
  • @Rinzwind apologies for replying so late; to clarify, yes the backup does complete, however tmutil continues to block until the dialogue is dismissed, meaning it will prevent further actions from starting if they are waiting for tmutil to finish. My problem is specifically that I'm using tmutil to trigger backup, then wish to do other stuff once it's done, but it can be greatly delayed if the dialogue pops up. – Haravikk May 8 '17 at 11:55

I don’t know whether you can suppress the dialog through tmutil directly.

The alternative, as you suggested, is to temporarily turn off the “Notify after old backups are deleted” option of the Time Machine options preferences through defaults:

sudo defaults write /Library/Preferences/com.apple.TimeMachine.plist AlwaysShowDeletedBackupsWarning 0

Use “1” instead of “0” to turn the option back on.

(I should perhaps specify that this answer applies to El Capitan, I don’t know about Sierra, though I assume this hasn’t changed.)

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Try read this article Control Time Machine command line`and this for delete Old Backups

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  • Can you give a summary of your findings? If your links die the answer is of no use to anyone here. Thx! – CousinCocaine Oct 1 '16 at 19:35

The defaults command to adjust the Time Machine backup interval is as follows, it belongs on a single line:

sudo defaults write /System/Library/LaunchDaemons/com.apple.backupd-auto StartInterval -int 14400

The last number is the time interval in seconds, making hours grouped by 3600 second segments. If you wanted to wait 4 hours between backups, the number would be 14400, and so on. The default setting is one hour, or 3600 seconds, which can be restored with:

sudo defaults write /System/Library/LaunchDaemons/com.apple.backupd-auto StartInterval -int 3600

Hit return and the default backup schedule will be restored again.

There is also a free program you can use to schedule times outside or terminal. http://www.klieme.com/TimeMachineScheduler.html

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