Comments on: Safer rm, more quickly

By: Juan

Juan — Tue, 09 Nov 2004 09:08:20 +0000

In the Book BSD Hacks (O’Reilly), Dru Lavigne explains a Hack for this making a Trash Directory and so solving this problem. I haven’t tried but seems to be interesting.

By: bern1;

bern1; — Thu, 07 Oct 2004 08:49:00 +0000

i did an rm accidently once:
i’ve been working for a long time and increased my speed of working as i wanted to go home.
…and a few seconds later, my /usr/local/etc directory was history.

the interesting part is:
the command was of course not:
rm -rf /usr/local/etc
(the -f is implied anyway on freebsd)

it was rather something like only:
rm -r etc
and i didn’t enter it myself, instead it was in my history after deleting a temporary etc directory somewhere else.

i quickly restored the directory from my last backup and didn’t think about it anymore…

but reading through your postings made me think about it once again:
in my opinion, any solution that is based on a confirmation has a reasonable weekness:

if you manage to accidently rm -rf /something, you will also manage to confirm your accident
and once you get used to a rm -r –f-even-more /something the whole mechanism is worth nothing.

my idea would be the following:

rm -rf /
> this is always stupid

rm -rf something
> operation not supported

rm -rf /absolute/path/to/something
> this is ok.

By: andre

andre — Thu, 07 Oct 2004 03:04:17 +0000

but then it would work only for rm… if i tried to remove a directory using, say, a ruby script, the srunlink flag would be ignored and the deletion would work.

By: mark

mark — Thu, 07 Oct 2004 00:53:57 +0000

File flag(s) are checked when rm stats a file, which it does prior to deletion. rm knows about the flag and about recursive deletion, so it can make the choice there- no kernel involvement required.

By: andre

andre — Wed, 06 Oct 2004 23:37:39 +0000

although i think this is a good idea, i believe it would not be easy to implement, since the kernel doesn’t know when a recursive deletion is going on (you delete each file in a directory with unlink() and then rmdir() the empty directory).

but maybe i’m completely wrong :)

By: Mark Miller

Mark Miller — Wed, 06 Oct 2004 19:11:02 +0000

The -I change seems like a good fix, but Matt missed one of the better developments that came out of that discussion: create a new file flag that forbids recursive deletion of a directory.

chflags srunlink /etc, for example, would stop any attempt to recursively remove /etc, and could be set/unset locally. I’d suggest that by default, the flag should be applied to /; smart admins can apply it to /etc, /usr/local/etc/, etc. as they see fit.