Messages in this thread | | | Date | Sun, 22 Nov 1998 15:50:38 -0500 (EST) | From | Ion Badulescu <> | Subject | RE: Possible bug in wait4(), 2.1.126-129 ? |
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On Sun, 22 Nov 1998, Greaves Tristan TM wrote:
> [cut lots of stuff] > > I missed the original posting here - could someone please tell me what > the actual symptons are, as I suspect I know what may be causing the > problem.
Basically, a perl script running another command using the backticks syntax (`foo`), from cron (this is important for some reason), ends up receiving ECHILD for the child's exit status.
Simplest test case:
#!/usr/bin/perl `cmp -s /bin/ls /bin/ls`; die "$!" if ($? != 0);
If I run this from cron (as root, haven't tried it yet as myself), I get a mail saying:
No child processes at <script filename> line 3.
In terms of system calls, it goes like this:
pipe() fork() [parent pid] read from pipe(... [child pid] do something [child pid] exit(0) [parent pid] read from pipe() resumed wait4(child pid) = -ECHILD
I can reproduce this at will. Yet, it's a "theoretically impossible" situation.
Ion
-- It is better to keep your mouth shut and be thought a fool, than to open it and remove all doubt.
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