Mac – Something Odd!

File system check exit code is 8.

I should have realised something was wrong when Lightroom previews were taking so long to generate. The disk holding my photo archive is corrupted, and macOS “First Aid” reports an exit code 8 when it does a file system check.

Luckily, the disk still mounts, and I have another disk where I can copy everything off, and multiple backups, but this is not a nice thing to wake up to.

On the other hand, there are hundreds of thousands of files there, and the file system check couldn’t tell me which ones were corrupted, and might need to be restored from Backblaze.

Don’t blindly follow AI instructions

I’m trying to share a Time Machine volume with another Macbook on my home network but it’s not working. I’ve tried Google, and read through a few Reddit threads, but I haven’t been able to get it to connect. So, I asked Perplexity for help.

It helpfully listed a number of things I could try, but then I saw tip number seven.

Clean up stale mount points: Sometimes, stale mount points can cause issues. You can try to remove them by running the following command in Terminal:

sudo rm -rf /Volumes/*

Then restart your Mac and attempt to mount the shares again.

When you look up advice online, don’t copy and paste any instructions into your computer without knowing what it does.

What does sudo rm -rf /Volumes/* do? It recursively deletes everything in your /Volumes folder. A little bit destructive.

I told it that was a dangerous command, and it went on to talk about using the mount command to list every mounted volume and then unmounting them with umount.

Me: Tip 7 is not helpful. That would delete all the data in /Volumes/

Perplexity: You’re absolutely right, and I sincerely apologize for that dangerous suggestion. Thank you for pointing out this critical error. You are correct that deleting the contents of /Volumes/ would be extremely harmful and could result in data loss. Let me provide a corrected and safer approach.

PS. Otherwise, Perplexity is great. I’ve had great success with it and other AI tools when developing software.

Pause Time Machine for large files?

Warning: this is potentially terrible advice as it disables your backup system temporarily, or until you remember to enable it again. It also deletes backups which might be needed if you need to restore a file that was modified during this period.

When downloading massive files like the 50GB tgz archives from Google Takeout on your Mac, you might consider temporarily pausing Time Machine backups. This can help avoid the creation of enormous snapshots that quickly consume your free space. It’s a bit perplexing, though—my Time Machine backup disk is always connected, so I’m unsure why snapshots are generated at all.

In theory, the operating system should delete or move those snapshots to your backup drive, but it seems to take its time. While most advice suggests leaving snapshots alone, some external tools can be finicky about free space. For example, Backblaze has complained when my internal drive space got too low.

To get an accurate picture of your available space, check the Storage Settings in System Settings. However, it can be disconcerting when the df -h command shows a much smaller figure. To quickly recover space, you can use Disk Utility’s “Show APFS Snapshots” feature to examine and delete any large backups.

Just remember to re-enable Time Machine as soon as you’ve moved those large files elsewhere. This approach does carry some risks: disabling your backup system leaves you vulnerable to data loss, and deleting backups may prevent you from restoring files modified during this period. Proceed with caution!

How to: a keyboard shortcut to lock your Mac

For many years, I was using a hot corner to lock the screen of my Mac, but I always wished there was the equivalent of Windows-L in Windows to do it.

I have no idea when this keyboard shortcut was added, but tapping the CTRL-CMD-Q shortcut will lock your Mac screen. Apparently, if you have a small magic keyboard, then CTRL-Shift-Eject will do the job too. This Stack Exchange Question shows the shortcut wasn’t available in 2015. Users had to resort to all sorts of tricks to lock their screen with the keyboard. An updated answer from 2019 reveals the shortcut, so I guess it’s at least four years old.

An apple on the side of the road — An apple on the ground. Like shortcuts, you never know what you’ll find.

Hot corners are great and all, but I’ve had so much trouble making sure the cursor stayed in the corner. I’d watch to make sure my mouse didn’t move, and the screen remained locked. Otherwise, I turn my back, I’m heading out the door and the screen lights up again!

Loads more keyboard shortcuts here if you’re interested in that sort of thing. That page may also explain why something strange happened on your computer while you were typing into the wrong window and changed a Finder setting, for instance.

Have fun getting locked.