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Re: Commands failing silently?

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Dan Bongert Re: [CentOS] Commands failing silently?
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William L. Maltby wrote:
> On Mon, 2008-03-24 at 16:19 -0500, Dan Bongert wrote:
>> mouss wrote:
>>> Dan Bongert wrote:
>>>> Hello all:
>>>>
>>>> <snip>
>
>
>> Though 'ls' was just an example -- just about any program will fail. The 'w'
>> command will fail too:
>>
>> thoth(118) /tmp> w
>> 16:06:51 up 5:34, 1 user, load average: 0.94, 1.46, 2.04
>> USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
>> dbongert pts/0 copland.ssc.wisc 14:16 0.00s 0.22s 0.05s w
>>
>> thoth(119) /tmp> w
>> 16:06:52 up 5:34, 1 user, load average: 0.94, 1.46, 2.04
>> USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
>> dbongert pts/0 copland.ssc.wisc 14:16 0.00s 0.22s 0.05s w
>>
>> thoth(120) /tmp> w
>>
>> thoth(121) /tmp> w
>>
>
> Hmmm... Sure it's failing? Maybe just the output is going somewhere
> else? After the command runs, what does "echo $?" show? Does it even
> work? Echo is a bash internal command, so I would expect it to never
> fail.

Ok, it's definitely getting an error from somewhere:

thoth(3) /tmp> ls

thoth(4) /tmp> echo $?
141

Although:

thoth(31) ~> top


thoth(32) ~> echo $?


> What is your output device? A serial terminal? If so, could be simple
> flow control issues. In fact, any serial connection (even a PC emulating
> a terminal) could suffer from flow control problems. And they would tend
> to be erratic in nature.

I'm usually sshing into the machine, but I've also experienced the problem
on the console.

> If you are on a normal console, try running the commands similart to
> this (trying to determine if *something* else is receiving output or
> not)
>
>     <your command> &> /dev/tty
>
> if this works reliably, maybe that's a starting point.

Nope, that fails intermittently as well.

> There's a couple kernel guys who frequent this list. Maybe one of them
> will have a clue as to what could go wrong. Corrupted libraries and
> whatnot.
>
> You might try that rpm -V command earlier against all packages (add a
> "a" IIRC). Maybe some library accessed by the coreutils, but which is
> not itself part of coreutils, is corrupt.

Hmm....when I do a 'rpm -Va', I get lots of "at least one of file's
dependencies has changed since prelinking" errors. Even if I run prelink
manually, and then do a 'rpm -Va' immediately afterwards.
--
Dan Bongert                     [email protected: dbo...@wisc.edu]

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Thread : Commands failing silently?
1)
Dan Bongert Hello all: I have a couple CentOS 4 servers (all up-to-date) that are having strange command...
2)
Bill Campbell There is a very good chance that the machine has been cracked, and the system's /bin/ls routine...
3)
Dan Bongert Everything seems OK there: thoth(96) /tmp> sudo rpm -V coreutils procps util-linux Funnily enough,...
4)
Peter l Jakobi That's funny. Or due to the output of strace changing timing & stress. Try redirecting the strace...
5)
mouss where is /tmp mounted? is this an external disk (usb, ...)? is it an nfs mount?
6)
Dan Bongert It's a local disk: thoth(97) /tmp> df -h . Filesystem Size Used Avail Use% Mounted on /dev/md4 16G...
7)
William L. Maltby Hmmm... Sure it's failing? Maybe just the output is going somewhere else? After the command runs,...
8)
Dan Bongert Ok, it's definitely getting an error from somewhere: thoth(3) /tmp> ls thoth(4) /tmp> echo $?...
9)
William L. Maltby "~>" ? Got me on that one. Ditto. Although I should mention that unless you "man bash" and find the...
10)
Filipe Brandenburger Hi, 141 is SIGPIPE. If the process is killed by a signal, the return code will be 128+signal...
11)
mouss maybe check your PATH. try $ /bin/ls ...
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