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Would running (rm deliberately broken)

sudo r m -rf / 

Wipe out any USB-attached external hard drives being used for time machine backups?

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up vote 2 down vote accepted

It might do that much damage - but it isn't a good area for experimentation.

I have seen a machine crippled because someone executed 'rm -fr /' as root - although it was done slightly less directly than shown. Fortunately, it was a brand new machine with no users on it and backups made already. At least they knew the backups worked.

The answer is not completely simple. For a start, you can't remove the mount points of directories leading to them. However, anything underneath a mount point (such as your Time Machine backups) could be removed if the system keeps running long enough. Secondly, it is hard to review what's left over afterwards; there aren't any commands left to let you do much. You'd have to boot off a CD of some sort and then inspect the residue. Thirdly, MacOS X has some settings which prevent even root from modifying some things sometimes - until you've adjusted the extended attributes etc.

But it will do a lot of damage. And you are advised not to try it on a machine where you care about the data on any of the attached disks. Unmount and detach the disks first - at least.

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I was hoping that the command of doom would unmount the hard drives rather than delete the contents. Oh well... – Andrew Grimm Apr 11 '10 at 5:01

AFAIK when you specify -r with rm it works from the bottom of the hierarchy up, so that the contents of the drives would go before their mount point was deleted.

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