GNU rm has exactly that built-in:

    $ rm -rf /
    rm: it is dangerous to operate recursively on ‘/’
    rm: use --no-preserve-root to override this failsafe

Go on, fire up a cheap VPS somewhere like DigitalOcean and run "rm -rf / --no-preserve-root". Maybe I am too easily amused but as a long-time Linux user on the desktop this is one of those things I always wanted to try. After it runs, you can't even shut down or run anything else, you just kill the SSH session.

How many daily-use scripts do you suppose intentionally run `rm -rf /`? Cost-benefit for common use seams clearly in favour of adding a failsafe.

It's a good thing you can fix the script by adding that flag into them.

I think this is kind of antithetical to the Unix philosophy.

If you add special exceptions for things like "rm -rf /" then you start to wonder, why not add exceptions for other dangerous things, like "find / -delete" and "rm -rf /usr".

In general, most of the basic Unix tools operate off of relatively simple first principles and don't contain exceptions for things like this.

When young I once had the opinion that such exceptions would be a good thing.

That is, until I installed some version of Red Hat that aliased rm to "rm -i", and extracted a few wrong tar files. Then I understood why the shell is that way, and why everybody just clicks "ok" on Windows dialog boxes without reading the alerts. Funny thing is that I lost some important files because I expected the prompt, but pressed "y" 19 times, instead of 18...

Nowadays I Just do backups.

First off, as someone already pointed out GNU rm does fail on `rm -rf /`. Secondly, that one is way more important than trying to protect `find / -delete` and `rm -rf /usr` because it's just way easier to mess up and have a stray slash in your command line.

Case in point, a unix novice coworker of mine came up to me once and said, I think I might have done something wrong. I'm trying to remove an empty directory and it's hanging. Turned out he created a directory in whatever linux workspace gui he was running at the time and accidentally added a space at the end. He didn't notice until he used terminal `ls` to look at it and then noticed it printed like this (with `ls -F`):

  somedir /

So he decided to rm it and start over. Can you guess what he typed?

For the record, GNU's Not Unix.

tarsnap forces you to type "No Tomorrow" when you try to delete all your backup. Something like that would be great.