Re: Interesting race condition...

Bill Davidsen
2004-07-27T20:38:07Z

Rob Landley wrote:
> On Friday 23 July 2004 05:01, P. Benie wrote:
>
>>On Fri, 23 Jul 2004, Rob Landley wrote:
>>
>>>I just saw a funky thing. Here's the cut and past from the xterm...
>>>
>>>[root@(none) root]# ps ax | grep hack
>>> 9964 pts/1 R 0:00 grep hack HOSTNAME= SHELL=/bin/bash TERM=xterm
>>>HISTSIZE=1000 USER=root
>>>LS_COLORS=no=00:fi=00:di=00;34:ln=00;36:pi=40;33:so=00;35:bd=40;33;01:cd=
>>>40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=00;32:*.cmd=00;32:*.exe=00;32:*.
>>>com=00;32:*.btm=00;32:*.bat=00;32:*.sh=00;32:*.csh=00;32:*.tar=00;31:*.tgz
>>>= [root@(none) root]# ps ax | grep hack
>>> 9966 pts/1 S 0:00 grep hack
>>>
>>>Seems like some kind of race condition, dunno if it's in Fedore Core 1's
>>>ps or the 2.6.7 kernel or what...
>>
>>The race is in the shell's pipeline - the processes don't start at exactly
>>the same time, and sometimes ps has completed before the shell has
>>started grep. This is the expected behaviour.
>
>
> It's expected behavior for PS to show a process's environment variables as
> part of its command line?

When piped. For instance
ps eaxf
does not, while
ps eaxf | cat
does, at least on my systems. I tried on RHEL AS3.0 thru a four year old
version of Slackware, all did the same thing.

--
-bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me