[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[Noel Chiappa]

    > From: Josh Good

    > Would the command "cd /tmp ; rm -rf .*" be able to kill a V6 ... system?

Looking at the vanilla 'rm' source for V6, it cannot/does not delete
directories; one has to use the special 'rmdir' command for that. But,
somewhat to my surprise, it does support both the '-r' and '-f' flags, which I
thought were later. (Although not as 'stacked' flags, so you'd have to say
'rm -r -f'.)

So, assuming one did that, _and_ (important caveat!) _performed that command
as root_, it probably would empty out the entire directory tree. (I checked,
and "cd /tmp ; echo .*" evaluates to ". .." on V6.

	Noel

[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[Josh Good]

On 2017 Apr 24, 18:06, Noel Chiappa wrote:
>     > From: Josh Good
> 
>     > Would the command "cd /tmp ; rm -rf .*" be able to kill a V6 ... system?
> 
> So, assuming one did that, _and_ (important caveat!) _performed that command
> as root_, it probably would empty out the entire directory tree. (I checked,
> and "cd /tmp ; echo .*" evaluates to ". .." on V6.

Yeah, but does "rm" in V6 has a built-in "brake" to not process "." nor
"..", no matter what ("-f")?

-- 
Josh Good

[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[Kurt H Maier]

On Tue, Apr 25, 2017 at 12:18:41AM +0200, Josh Good wrote:
> On 2017 Apr 24, 18:06, Noel Chiappa wrote:
> >     > From: Josh Good
> > 
> >     > Would the command "cd /tmp ; rm -rf .*" be able to kill a V6 ... system?
> > 
> > So, assuming one did that, _and_ (important caveat!) _performed that command
> > as root_, it probably would empty out the entire directory tree. (I checked,
> > and "cd /tmp ; echo .*" evaluates to ". .." on V6.
> 
> Yeah, but does "rm" in V6 has a built-in "brake" to not process "." nor
> "..", no matter what ("-f")?
> 
> -- 
> Josh Good
> 

rm in V6 outsources globbing to /etc/glob, which appears to report
no-match if the first character is .
       
https://github.com/dspinellis/unix-history-repo/blob/Research-V6-Snapshot-Development/usr/source/s1/glob.c#L151
       
khm

[TUHS] was turmoil, moving to rm -rf /

[Larry McVoy]

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

[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[Ron Natalie]

> rm in V6 outsources globbing to /etc/glob, which appears to report
> no-match if the first character is .

Actually, it's the shell that calls glob.   Glob then invokes the command
(in this case rm).

Anyhow, that doesn't do what you think it does.    It ignores directory
entries that begin with '.' if the search string doesn't begin with ..

".*"  will indeed match ".."

Of course, the calamity depends on whether you have /tmp on it's own
filesystem.   V6 didn't go .. off the top of the filesystem, the root ..
just linked back to the inode 1 (the root itself).

[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[Kurt H Maier]

On Mon, Apr 24, 2017 at 08:06:28PM -0400, Ron Natalie wrote:
> 
> 
> > rm in V6 outsources globbing to /etc/glob, which appears to report
> > no-match if the first character is .
> 
> Actually, it's the shell that calls glob.   Glob then invokes the command
> (in this case rm).
> 
> Anyhow, that doesn't do what you think it does.    It ignores directory
> entries that begin with '.' if the search string doesn't begin with ..
> 
> ".*"  will indeed match ".."
> 
> Of course, the calamity depends on whether you have /tmp on it's own
> filesystem.   V6 didn't go .. off the top of the filesystem, the root ..
> just linked back to the inode 1 (the root itself).
> 
> 

Thanks for correcting my hasty conclusions.  /usr/source/s2/rm.c has an
execl call in the rm() function, but I didn't dig further into the
calling mechanism.  

V7's /usr/src/cmd/rm.c definitely explicitly has a check for '..' and 
an error message dedicated to the task.  

So I think we can conclude that unix got this protection sometime
between V6 and V7 -- in other words, sometime in the late 1970s. 

And systemd is now catching up.  "Those who do not study unix" etc

khm

[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[ron minnich]

On Mon, Apr 24, 2017 at 5:18 PM Kurt H Maier <khm at sciops.net> wrote:

>
>
> And systemd is now catching up.  "Those who do not study unix" etc
>
>

not catching up, as I read the discussion it is marked as "working as
intended".
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[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[Kurt H Maier]

On Tue, Apr 25, 2017 at 12:22:44AM +0000, ron minnich wrote:
> On Mon, Apr 24, 2017 at 5:18 PM Kurt H Maier <khm at sciops.net> wrote:
> 
> >
> >
> > And systemd is now catching up.  "Those who do not study unix" etc
> >
> >
> 
> not catching up, as I read the discussion it is marked as "working as
> intended".


They committed a patch to fix it.  The project maintainer declared it a
non-problem ex post facto and met with some derision... but by that
point they at least had a safeguard in place.

khm

[TUHS] There is turmoil in Linux-land - When did rm first avoid going upwards?

[ron minnich]

On Mon, Apr 24, 2017 at 5:24 PM Kurt H Maier <khm at sciops.net> wrote:

>
>
>
> They committed a patch to fix it.  The project maintainer declared it a
> non-problem ex post facto and met with some derision... but by that
> point they at least had a safeguard in place.
>
> khm
>

ah, good to know.
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[TUHS] was turmoil, moving to rm -rf /

[Dan Cross]

Am I the only one who mentally says, "f*ck recursively" whenever I type,
"rm -fr" ? (f*ck being fsck, of course.)

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
>
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[TUHS] was turmoil, moving to rm -rf /

[Clem Cole]

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
>
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[TUHS] was turmoil, moving to rm -rf /

[Larry McVoy]

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 

[TUHS] was turmoil, moving to rm -rf /

[Álvaro Jurado]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 3396 bytes --]

I did it during my IBM days years ago. It was an AIX 4.2, I broke almost a
half of /usr and /bin /etc... ashamed :-(

Álvaro

2017-04-25 16:08 GMT+02:00 Larry McVoy <lm at mcvoy.com>:

> 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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[TUHS] was turmoil, moving to rm -rf /

[Clem Cole]

Problem was /etc has been burned too...  so the mknod command is off the
table.


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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[TUHS] was turmoil, moving to rm -rf /

[Corey Lindsly]

> 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.

It was in a situation similar to this that I learned the blessed 
usefulness of echo * as a crude substitute for /bin/ls 

--corey

[TUHS] was turmoil, moving to rm -rf /

[arnold]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 3671 bytes --]

I too, on a 4.1 BSD or 4.2 BSD vax 780 at Ga Tech.  I forget who helped
me put things back together.  IIRC I had blown away "only" /dev, so it
wasn't quite so bad.

But yes, it's something you only do once.  :-)

Arnold

Álvaro Jurado <elbingmiss at gmail.com> wrote:

> I did it during my IBM days years ago. It was an AIX 4.2, I broke almost a
> half of /usr and /bin /etc... ashamed :-(
>
> Álvaro
>
> 2017-04-25 16:08 GMT+02:00 Larry McVoy <lm at mcvoy.com>:
>
> > 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
> >

[TUHS] was turmoil, moving to rm -rf /

[Álvaro Jurado]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 4225 bytes --]

My mstake was forgetting that "su -" is not "su". So I thought I was on the
right dir and...

Álvaro

2017-04-25 16:29 GMT+02:00 <arnold at skeeve.com>:

> I too, on a 4.1 BSD or 4.2 BSD vax 780 at Ga Tech.  I forget who helped
> me put things back together.  IIRC I had blown away "only" /dev, so it
> wasn't quite so bad.
>
> But yes, it's something you only do once.  :-)
>
> Arnold
>
> Álvaro Jurado <elbingmiss at gmail.com> wrote:
>
> > I did it during my IBM days years ago. It was an AIX 4.2, I broke almost
> a
> > half of /usr and /bin /etc... ashamed :-(
> >
> > Álvaro
> >
> > 2017-04-25 16:08 GMT+02:00 Larry McVoy <lm at mcvoy.com>:
> >
> > > 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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[TUHS] was turmoil, moving to rm -rf /

[Dan Cross]

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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[TUHS] was turmoil, moving to rm -rf /

[Pete Turnbull]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 316 bytes --]

On 25/04/2017 15:31, Álvaro Jurado wrote:
> My mstake was forgetting that "su -" is not "su". So I thought I was on
> the right dir and...

Not for quite the same reason, but on all my machines I've taken to 
creating a home directory for root that isn't / for the last couple of 
decades.

-- 
Pete
Pete Turnbull

[TUHS] was turmoil, moving to rm -rf /

[Bakul Shah]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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I once had to rebuild the root directory using ROM based disk IO and memory peek and poke commands!  At this late date I don’t recall many details but at least the root block was trashed during some last minute testing. Unlikely it was “rm -rf / something” as that would’ve done far more damage.

The situation was this:
1. We had *one* working hardware system[1].
2. At that time we only had working floppy controller and driver[2].
3. Our devel system was a VAX running 4.1BSD. no support for the floppy drive so everything had to be downloaded over a 9600 serial link.
4. The backup floppy either didn’t exist or wasn’t readable.
5. We had custom stuff that was done for a show and not backed up anywhere.

Luckily, due to earlier debugging sessions I knew what the file system layout was — this was on a version 7 system, with 16 byte dir entries, 2 bytes inode #, followed by and 14 byte name. IIRC inode 0 was not used, inode 1 was used as a temp during fsck based recovery and inode 2 was for the real root. So I read in the root inode, found the disk address of its data block, read it in, using fixed up “.” and “..” and “/bin” entries — usually inode #3 was bin, wrote it back to the floppy and rebooted. I think the unix image was in /bin. On reboot fsck worked and reconnected all the lost directories, which were easy to figure out and rename.

The back story is that this happened on a Saturday just before the Fall Comdex 1981, where we were going to show our system for the first time and we had to take a working system to Las Vegas by Sunday[3]. We were able to fly out on time and the Comdex show was a success, with thousands of leads generated.

In terms of lessons, I don’t know what we learned. I guess it pays to be intimately familiar with the system as we were in an extreme bootstrap situation with very little working reliably. Seems often startups end up doing acrobatics without a net!

— bakul

[1]  Two actually, but the second was a wire wrapped prototype. This was at an early Unix workstation startup; our main app was “word processing”.

[2] Later we hooked up a Western Digital ST506 controller via parallel port and I was very happy when my disk driver could do 25 KB/s! No DMA so had to do programmed IO.

[3] Rob Warnock (whom some of you may know from his SGI days) was our very hands-on CTO, and he was/is great at debugging/problem solving. I don’t know why they waited for me rather than call Rob. a) I was a junior engineer as that my first job with C & Unix  (6 months at that time) and b) I had already worked about 80+ hours that week and gone home to sleep at 9AM on Saturday. May be Rob was smart enough to not answer his phone!

> On Apr 25, 2017, at 8:28 AM, Dan Cross <crossd at gmail.com> wrote:
> 
> On Tue, Apr 25, 2017 at 10:18 AM, Clem Cole <clemc at ccc.com <mailto: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 <mailto: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 <mailto: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 <http://mcvoy.com/lm/masscomp-restore.pdf>
> > >
> > > Complete with all the typos.
> > >
> > > --lm
> > >
> 
> --
> ---
> Larry McVoy                  lm at mcvoy.com <http://mcvoy.com/>             http://www.mcvoy.com/lm <http://www.mcvoy.com/lm>
> 
> 

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[TUHS] was turmoil, moving to rm -rf /

[Steve Johnson]

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The worst "nuke the file system" experience I had was on the GE
mainframe.  Think big room, punched cards, etc.  And an operators'
console that typed on paper...

When you booted the system, the first message that came up said:

    INIT?

If you said 'y', it wiped out the file system.

After a very heated users' group meeting, they agreed to change the
message to

DO YOU WANT TO WIPE OUT THE FILE SYSTEM?

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[TUHS] was turmoil, moving to rm -rf /

[Ron Natalie]

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Exec 8 (the Univac Operating Systm) used to make you type the word “CATASTROPHIC” to proceed past a certain point in reiniting the system.

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[TUHS] was turmoil, moving to rm -rf /

[Toby Thain]

On 2017-04-27 7:44 PM, Steve Johnson wrote:
> The worst "nuke the file system" experience I had was on the GE
> mainframe.  Think big room, punched cards, etc.  And an operators'
> console that typed on paper...
>
> When you booted the system, the first message that came up said:
>
>     INIT?
>
> If you said 'y', it wiped out the file system.
>
> After a very heated users' group meeting, they agreed to change the
> message to
>
> DO YOU WANT TO WIPE OUT THE FILE SYSTEM?


Good to know UX has always been terrible :-)

--T

[TUHS] was turmoil, moving to rm -rf /

[arnold]

Toby Thain <toby at telegraphics.com.au> wrote:

> On 2017-04-27 7:44 PM, Steve Johnson wrote:
> > The worst "nuke the file system" experience I had was on the GE
> > mainframe.  Think big room, punched cards, etc.  And an operators'
> > console that typed on paper...
> >
> > When you booted the system, the first message that came up said:
> >
> >     INIT?
> >
> > If you said 'y', it wiped out the file system.
> >
> > After a very heated users' group meeting, they agreed to change the
> > message to
> >
> > DO YOU WANT TO WIPE OUT THE FILE SYSTEM?
>
>
> Good to know UX has always been terrible :-)
>
> --T

Well golly gee whiz, the guy who wrote it knew what it was
going to do ...  ( :-)

Arnold

[TUHS] was turmoil, moving to rm -rf /

[John Floren]

On 2017-04-27, Ron Natalie <ron at ronnatalie.com> wrote:
> This is a multipart message in MIME format.
>
> ------=_NextPart_000_0154_01D2BF90.27157840
> Content-Type: text/plain;
> 	charset="UTF-8"
> Content-Transfer-Encoding: quoted-printable
>
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>
>
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> ------=_NextPart_000_0154_01D2BF90.27157840--
>

Ron, can you and others who are posting via email please take care to
send text-only emails? It's utterly unreadable to anyone using a newsreader
or plain old 'mail'. http://i.imgur.com/EJS5Okd.png

sorry for going off-topic...

john

[TUHS] was turmoil, moving to rm -rf /

[David]

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Many years ago I was at Burroughs and they wanted to do Unix (4.1c) on a new machine. Fine. We all started on the project porting from a Vax. So far so good. Then a new PM came in and said that intel was the future and we needed to use their machines for the host of the port. And an intel rep brought in their little x86 box running some version of Unix (Xenix?, I didn’t go anywhere near the thing). My boss, who was running the Unix port project did the following:
Every Friday evening he would log into the intel box as root and run “/bin/rm -rf /“ from the console. Then turn off the console and walk away.
Monday morning found the box dead and the intel rep would be called to come and ‘fix’ his box.
This went on for about 4 weeks, and finally my boss asked the intel rep what was wrong with his machine.
The rep replied that this was ‘normal’ for the hardware/software and we would just have to “get used to it”.
The PM removed the intel box a couple of days later.

	David

> On Apr 25, 2017, at 7:19 AM, tuhs-request at minnie.tuhs.org wrote:
> 
> From: Larry McVoy <lm at mcvoy.com>
> To: Clem Cole <clemc at ccc.com>
> Cc: Larry McVoy <lm at mcvoy.com>, TUHS main list <tuhs at minnie.tuhs.org>
> Subject: Re: [TUHS] was turmoil, moving to rm -rf /
> Message-ID: <20170425140853.GD24499 at mcvoy.com>
> Content-Type: text/plain; charset=us-ascii
> 
> 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 :)