From: crossd@gmail.com (Dan Cross)
Subject: [TUHS] was turmoil, moving to rm -rf /
Date: Tue, 25 Apr 2017 11:28:21 -0400 [thread overview]
Message-ID: <CAEoi9W7_caF5y0ofR8xNU-y5aH2vLzEoC-xJZVDbHbwyHWj8jA@mail.gmail.com> (raw)
In-Reply-To: <CAC20D2OZknn5R=0HJm8C26hwWwboekEQMK_YHV73iVby_WVTkw@mail.gmail.com>
On Tue, Apr 25, 2017 at 10:18 AM, Clem Cole <clemc at ccc.com> wrote:
> Problem was /etc has been burned too... so the mknod command is off the
> table.
>
Either boot into standalone media like some kind of miniroot (that
hopefully has a copy of mknod) or look for some kind of shell builtin?
E.g., if the shell provides some mechanism to make a raw system call, you
can do it. E.g., an escape hatch to syscall() or indir(). If a copy of
`mkdir` survived, then on older systems where directory creation was done
by calling mknod(), one might be able to modify `mkdir` enough to create
device file for a tape device to launch a restore off of. I thought some
systems came with a syscall(1) utility, but it does't seem to be current
anymore and I can't find any references to it so perhaps I'm misremembering.
I once messed up a NeXT machine by "mv"'ing the system shared libraries to
an unexpected path. Oops. I had to boot off the CD to fix it, but that's
child's play compared to some of the esoterica you guys are talking about.
- Dan C.
On Tue, Apr 25, 2017 at 10:08 AM, Larry McVoy <lm at mcvoy.com> wrote:
>
>> Whoever was the genuis that put mknod in /etc has my gratitude.
>> We had other working Masscomp boxen but after I screwed up that
>> badly nobody would let me near them until I fixed mine :)
>>
>> And you have to share who it was, I admitted I did it, I think
>> it's just a thing many people do..... Once :)
>>
>> On Tue, Apr 25, 2017 at 10:02:26AM -0400, Clem Cole wrote:
>> > Larry,
>> >
>> > I had to laugh when I read that because what you don't know is it was
>> part
>> > of my old Unix wizards test which was left over from a the day when one
>> of
>> > our hackers (whom I think you would later get to know so I'll not name
>> him)
>> > accidentally typed: rm -rf . as root from his / on his workstation.
>> >
>> > Because /bin/rmdir had been lost, he started getting errors when rmdir
>> was
>> > forked. So he hit ^C, but he had already lost: /bin, /dev, /etc,
>> /lib,
>> > most of /usr. He was a developer in the networking group so he was
>> working
>> > on network code which we could not trust would not panic (in fact we
>> > disconnected the node from the ethernet immediately just in case).
>> But we
>> > did have pretty much everything in /usr/bin/[s-z]* -- that is we think
>> it
>> > was deleting files in /usr/bin when he stopped it.
>> >
>> > We obviously had another working Masscomp box just like it. And of
>> course
>> > the shell was working on the machine that was in trouble. We recovered
>> > the system as it was. Hint the key item is you have to start by
>> putting
>> > /dev back together and the solution to that problem has had been
>> discussed
>> > on this list.
>> >
>> > Clem
>> >
>> > On Mon, Apr 24, 2017 at 7:59 PM, Larry McVoy <lm at mcvoy.com> wrote:
>> >
>> > > This is gonna seem like I'm tooting my own horn, and I am a little,
>> but
>> > > here's an rm -rf / story.
>> > >
>> > > Clem will be amused because I was a junior or senior in college and a
>> sys
>> > > admin for a Masscomp with a 40MB disk with 20 users. And I did some
>> > > version
>> > > of rm -rf /, realized part way through that I screwed up, and killed
>> it.
>> > > But /bin and /dev were gone so putting things back together was hard.
>> > >
>> > > But I did it and wrote up this little note for the people who came
>> after
>> > > me, if I was stupid enough to do this someone else would, was my
>> thinking.
>> > > You can get a sense of how scared I was in it if you read it
>> carefully.
>> > > It was a very long night.
>> > >
>> > > For an undergrad, I think it's not bad? Maybe? I dunno, I look at
>> how
>> > > much I needed to have understood to get the system back up, that's a
>> lot
>> > > of reading, playing, experience. Love that Geophysics department,
>> they
>> > > pushed me.
>> > >
>> > > And it was during my (brief) foray into the *roff -me macros (I went
>> > > -ms and never looked back). Roff source on request to anyone who is
>> > > twisted enough to want it.
>> > >
>> > > http://mcvoy.com/lm/masscomp-restore.pdf
>> > >
>> > > Complete with all the typos.
>> > >
>> > > --lm
>> > >
>>
>> --
>> ---
>> Larry McVoy lm at mcvoy.com
>> http://www.mcvoy.com/lm
>>
>
>
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next prev parent reply other threads:[~2017-04-25 15:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-24 22:06 [TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards? Noel Chiappa
2017-04-24 22:18 ` Josh Good
2017-04-24 23:23 ` Kurt H Maier
2017-04-24 23:59 ` [TUHS] was turmoil, moving to rm -rf / Larry McVoy
2017-04-25 0:44 ` Dan Cross
2017-04-25 14:02 ` Clem Cole
2017-04-25 14:08 ` Larry McVoy
2017-04-25 14:12 ` Álvaro Jurado
2017-04-25 14:29 ` arnold
2017-04-25 14:31 ` Álvaro Jurado
2017-04-25 16:28 ` Pete Turnbull
2017-04-27 23:44 ` Steve Johnson
2017-04-27 23:54 ` Ron Natalie
2017-04-28 3:04 ` Toby Thain
2017-04-28 5:19 ` arnold
[not found] ` <mailman.198.1493337336.3780.tuhs@minnie.tuhs.org>
2017-04-28 14:48 ` John Floren
2017-04-25 14:18 ` Clem Cole
2017-04-25 15:28 ` Dan Cross [this message]
2017-04-25 17:56 ` Bakul Shah
2017-04-25 14:19 ` Corey Lindsly
2017-04-25 0:06 ` [TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards? Ron Natalie
2017-04-25 0:18 ` Kurt H Maier
2017-04-25 0:22 ` ron minnich
2017-04-25 0:24 ` Kurt H Maier
2017-04-25 0:26 ` ron minnich
[not found] <mailman.805.1493129956.3779.tuhs@minnie.tuhs.org>
2017-04-25 15:17 ` [TUHS] was turmoil, moving to rm -rf / David
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