Date: Thu, 10 Jun 2010 09:45:44 +0200 From: Jonathan McKeown <j.mckeown@ru.ac.za> To: freebsd-questions@freebsd.org Subject: Re: why does ps |grep sometimes not return itself? Message-ID: <201006100945.44151.j.mckeown@ru.ac.za> In-Reply-To: <201006100330.14618.pieter@degoeje.nl> References: <AANLkTimdtot-1vlYofXo-dv3V7jyFW7VU0D6dq3vqBqV@mail.gmail.com> <4C0F4410.40900@infracaninophile.co.uk> <201006100330.14618.pieter@degoeje.nl>
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On Thursday 10 June 2010 03:30:14 Pieter de Goeje wrote: > On Wednesday 09 June 2010 09:34:40 Matthew Seaman wrote: > > On 09/06/2010 08:15:23, Eitan Adler wrote: > > > Why do I sometimes see the grep in ps's output and sometimes not see > > > it? > > > > When you run that pipeline the OS doesn't start both programs exactly > > simultaneously. [...] It's a race condition. > > I would like to add that you can avoid the issue entirely by using this > command: > % ps aux -p `pgrep sh` [output snipped due to bad wrapping] Or the old trick: ps | grep '[s]h' Jonathan
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