RE: a nice way to reboot :-)

From: Van Maren, Kevin <kevin.vanmaren_at_unisys.com>
Date: 2003-07-24 23:53:27
I think we've beaten this to death: yes, it is an annoying bug, and
deserves to be fixed.

Just to clarify: I think you want to use tar with --exclude=/proc or -l;
tar doesn't have an -xdev option (that is for find, used with cpio).
I've also used --exclude-from=/nodump where /nodump lists the
directories to skip: /tmp, /proc, /dev, etc.  I actually started
doing that because my IA64 Linux system rebooted when using tar to
backup (several filesystems at once) to tape :-(
Also note that those are GNU tar extension, and are not available
on SysV (but then, I've never seen a SVR4 machine reboot reading /proc).

Andreas, I don't think your analogy is even close: tar is documented
create an archive; shutdown is documented to reboot the system:
what Bruno was saying is that running tar (even on /proc) is no more
expected to reboot the system than doing an "ls" on /proc.
The UnitedLinux man page for tar makes no indication that root can
reboot the system with it...  Even worse, this behavior does not
occur on other Linux/BSD systems, so people don't have a "reasonable
expectation" for it to kill the system, especially when "properly"
invoked.  (Now, trying to extract an old /proc from a tarfile is
different -- I'll believe that attempting to replace /proc could
reasonably be expected to cause problems, but not reading /proc).

Kevin

-----Original Message-----
From: Andreas Schwab [mailto:schwab@suse.de]
Sent: Thursday, July 24, 2003 6:52 AM
To: Bruno Cornec
Cc: Matthew Wilcox; ia64-list; giovanni_pala@hp.com
Subject: Re: a nice way to reboot :-)


Bruno Cornec <Bruno.Cornec@hp.com> writes:

|> I just wonder if this could be used as a DOS from outside the system. In
|> which case, it would be a Bad Thing (tm :-)
|> 
|> > root can crash
|> > the system any way they want.  
|> 
|> Yes, that's true. But it just more surprising when you think you just
|> pass a normal command ;-)

If you are already root then shutdown -h is just as effective.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg
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"And now for something completely different."
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Received on Thu Jul 24 09:57:32 2003

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