Primary Unit

David Sparks posted this week about ejecting disks using AppleScript and Keyboard Maestro. I’m grateful to David for posting about this — it’s something I’ve needed for a while but hadn’t got around to doing. Currently I plug my laptop into several external drives when I’m sat at my desk, and have to eject them before taking it somewhere more relaxed.

But David’s script didn’t quite work for me in that a blunt eject the disks command to the Finder will attempt to eject all the disks that are considered “ejectable”. For me, this includes APFS snapshots that aren’t obviously visible in the user interface, where trying to eject them pops up a dialog referencing “Macintosh HD – Data@snap…”.

My alternative is to filter out any drives that contain “Macintosh HD” in their displayed name:

tell application "Finder"
    eject (every disk where "Macintosh HD" is not in its displayed name)
end tell

Note that it’s important to use the displayed name property as the APFS snapshots have UUIDs as their name property.

I’ve also stripped out David’s error handling, as I find that if there’s an error ejecting the disk it’s usually communicated by the Finder itself rather than via an error code visible to AppleScript.

This doesn’t tackle the problem of the Finder refusing to eject a drive containing opened files, even if those files are opened by (from the user’s perspective) unimportant background commands. I spent a chunk of the morning mulling this over (and looking at lsof’s inscrutable man page!), and think I might try to run the output of lsof -F through AWK to enable a prompt-to-terminate interface. This is particularly important for me as I keep my music and photo libraries on an external drive; the photo library in particular is often opened by background system tasks, I think as iCloud syncs across new photos from my phone.