Unix Admin Horror Story Summary (1992)

Re:Unix Admin Horror Story Summary (1992) by geocrasher on Tuesday December 21, 2021 @05:15PM (#29642772)

This one made me LOL:

   My mistake on SunOS (with OpenWindows) was to try and clean up all the
   '.*' directories in /tmp. Obviously "rm -rf /tmp/*" missed these, so I
   was very careful and made sure I was in /tmp and then executed
   "rm -rf ./.*".

   I will never do this again. If I am in any doubt as to how a wildcard
   will expand I will echo it first.

I read this, and just had to go try it because I couldn't picture it in my brain. Here it is:

   $ echo ./.*
   ./. ./..

So if you're in /tmp/ and do 'rm -rf ./.*', it's

  rm -rf ./. ./..

and ./.. is .. which from tmp is /. Thankfully we have protections against this now. Back then, not so much.

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Re:Unix Admin Horror Story Summary (1992) by simonblack on Tuesday December 21, 2021 @07:27PM (#29643939)

As a brand-new UNIX user around 1991 and coming from MSDOS, I was used to being 'God' on my machine so I thought it would be a good idea to login always as 'root'. I couldn't understand why long-time users of UNIX knew that to be a very bad idea, and always advised against it.

Like the SunOS person, I had lots of dot-directories in /tmp. So I duplicated his actions almost perfectly.

Also like he did, I was wondering why an 'instantaneous' action was taking so long. I had to do a complete re-installation.

Ever since then, I've always logged in as a 'normal user'. My reign as 'God' in a UNIX environment lasted about 2-3 weeks in total.

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Re:Unix Admin Horror Story Summary (1992) by yjftsjthsd-h on Tuesday December 21, 2021 @06:21PM (#29643345)

Huh, what do you know. I thought modern rm only protected against deleting / by absolute path, but it looks like it'll protect you from deleting your parent regardless:

    $ docker run --rm -ti debian:11  # sandbox the danger...
    root@c70dde9f38a3:/# cd /tmp
    root@c70dde9f38a3:/tmp# rm -rf ./.
    rm: refusing to remove '.' or '..' directory: skipping './.'
    root@c70dde9f38a3:/tmp# mkdir -p /tmp/1/2/3/4/5
    root@c70dde9f38a3:/tmp# cd /tmp/1/2/3/4/5
    root@c70dde9f38a3:/tmp/1/2/3/4/5# rm -rf ./.
    rm: refusing to remove '.' or '..' directory: skipping './.'

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Re:Unix Admin Horror Story Summary (1992) by tomlx on Wednesday December 22, 2021 @12:23AM (#29645868)

Interestingly

  $ bash -c 'cd /var/empty; echo .*'
  . ..

but

  $ ksh -c 'cd /var/empty; echo .*'
  .*

Seems some ksh dev got bitten and restricted this ...

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Re:Unix Admin Horror Story Summary (1992) by lsh123 on Tuesday December 21, 2021 @10:18PM (#29645226)

Actually this is exactly what Oracle installer did in 93-94 after a jr sysadmin tried to install it from /tmp.

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