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Re: Strange behaviour on 'read' from a pipe
From: |
Lluís Batlle i Rossell |
Subject: |
Re: Strange behaviour on 'read' from a pipe |
Date: |
Sun, 1 Apr 2012 10:52:30 +0200 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
On Sat, Mar 31, 2012 at 09:16:20PM -0400, Chet Ramey wrote:
> On 3/31/12 9:19 AM, Lluís Batlle i Rossell wrote:
> > Hello,
> >
> > I have this script, that I've found to never write "DONE" in my systems,
> > with
> > bash 4.0, 4.1, 4.2.. until 4.2-p20, my last test.
> >
> > However, in irc some people told me it prints DONE for them. If I run the
> > script with
> > bash under 'strace -f', it also prints DONE.
>
> It looks like a simple race condition. I suspect that the scheduler
> arranges things so that the child process ends up exiting between the
> open and the read, but I don't have any real evidence to back it up.
> (Like you, my Mac OS X system prints `DONE'.)
>
> You might want to try using exec to open the FIFO in the parent process
> rather than trying to open it on each read.
Yes, I know I can work around it, but I meant that the race of the parent
getting SIGCHLD in the read call did not bring any useful outcome.
For me, useful outcomes could be:
- read nothing, and unblock with error
- keep on reading the same fd
But it does not do any of those.
Thank you,
Lluís.
- Re: Strange behaviour on 'read' from a pipe,
Lluís Batlle i Rossell <=
- Re: Strange behaviour on 'read' from a pipe, Andreas Schwab, 2012/04/01
- Re: Strange behaviour on 'read' from a pipe, Lluís Batlle i Rossell, 2012/04/01
- Re: Strange behaviour on 'read' from a pipe, Chet Ramey, 2012/04/01
- Re: Strange behaviour on 'read' from a pipe, Lluís Batlle i Rossell, 2012/04/01
- Re: Strange behaviour on 'read' from a pipe, Chet Ramey, 2012/04/01
- Re: Strange behaviour on 'read' from a pipe, Lluís Batlle i Rossell, 2012/04/02
- Re: Strange behaviour on 'read' from a pipe, Lluís Batlle i Rossell, 2012/04/02
- Re: Strange behaviour on 'read' from a pipe, Lluís Batlle i Rossell, 2012/04/02
- Re: Strange behaviour on 'read' from a pipe, Greg Wooledge, 2012/04/02
- Re: Strange behaviour on 'read' from a pipe, Lluís Batlle i Rossell, 2012/04/02