James G. Sack (jim) wrote:
Ralph Shumaker wrote:
Gabriel Sechan wrote:
From: Ralph Shumaker <[EMAIL PROTECTED]>
Stewart Stremler wrote:
begin quoting Lan Barnes as of Fri, Apr 06, 2007 at 04:19:02PM -0700:
[snip]
I was taught that command in my first or second Unix class, long
before I
was allowed near a keyboard.The instructor said write this down and
memorize it so you never do it by accident.
When you type "rm -rf", you should sit back, and put your hands in your
lap for a second. Think of it as a zen moment.
Why would anyone actually *want* to use that command? (Serious
question.)
The -r? I frequently want to delete an entire directory. The -f?
Because sometimes files are marked read only. Examples on a daily
basis- tarballs and SCM systems frequently leave read only files on
your hard drive.
Granted, but given the potential for destruction from that command, one
would think that the command invoked with those switches would caution
the human when invoked on "/" or even a first level directory before
poceeding.
At least one would think that --preserve-root would be on by default.
Further, one would think that this switch would also protect first level
directories at least.
Oh well, I guess it would be best to take SS's practice of mounting
certain volumes read only. That would have prevented the largest part
of the problem in the story in the link. If /etc and all the essential
binaries were in a volume mounted read only, they could have saved
themselves a lot of headaches. Had the Vax assembly programmer *not*
been there, ... , or the emacs had *not* been open, ... , or any of the
other happy coinky-dinks, a read only system of the base OS (and device
drivers) would have been a godsend.
Another practical recommendation:
Never include _any_ paths in a rm -rf command
That is, if you want to get rid of a tree at /path/to/somedir
Always cd to the direct parent .. cd /path/to
Run the command with the bare dir name .. rm -rf somedir
The idea: if you _never have any slash_ in the command then you can't
accidentally get a disaster such as could happen with inadvertent
spaces, such as
rm -rf / path/to/somedir .. would operate on '/' OOPS
Chilling! Brrrr!
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