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Protecting Rm
A.P. Lawrence
Contributing Writer
2006-06-29
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It was once very fashionable in Linux distros to alias rm to "rm -i". I don't see that as often as I used to, which surprises me: it can only mean that everyone else hates that as much as I do.
Seriously: how often do you screw up and remove something you shouldn't have? Sure, it happens: misplaced wildcards or a slip of the finger can do it. More than once I've meant to do something like "rm *.bak" and accidentally put a space after the "*". This stuff happens, but it happens so infrequently that it's not worth putting up with "rm -i" the rest of the time.
And when I do screw up, how bad can the damage be if I'm not running as root?
If you do happen to be root, the damage can be horrible. I have to admit that yes, I have (once) accidentally typed "rm -r /". Worse, I did it during a training session on a live system. The results were dramatic and embarrassing. Fortunately I saved most of it by immediately pulling the power plug, so little had a chance to commit from cache, but I still had a bit of restoring to do. That was a bad day.
I think that while "rm -i" is annoying, a new "-ii" (intelligent interactive) could be less so. In my version, "rm -ii" would be silent and immediately obedient when asked to remove one file. With more than one, the first thing it would do is get an approximate count - to save time it wouldn't look very far, but might instead say "You are matching more than 20 files". Perhaps both of these limits should be user configurable: "rm -ii 1:20" is clumsy. but as it would probably ordinarily be used as an alias, that's unimportant. The most important part is the simple addition of a "c" answer, which would stop asking for confirmation and just remove the remaining files. You could give that at any time, of course. That "ii" could save you from disaster without being quite so annoying.
Somebody had the thought that not even root should be able to remove the earth it stands on. See "rm -rf /" protection at "Meddling in the Affairs of Wizards" for the interesting story of how they got that by the standards committee.
*Originally published at APLawrence.com
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About the Author:
A.P. Lawrence provides SCO Unix and Linux consulting services http://www.pcunix.com
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