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Subject: Re: vfork always fail problem
References: <AANLkTik_jo0N1YtUTFLzsqAsv5OkkyjCG9epeMq55bWk AT mail DOT gmail DOT com>
Date: Fri, 14 May 2010 09:38:40 +0200
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From: "Matthias Andree" <matthias DOT andree AT gmx DOT de>
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Am 14.05.2010, 06:29 Uhr, schrieb Huang Bambo:

> [Bambo AT bambo-notebook 4.4.4]$ cat tvfork.c
> #include <sys/types.h>
> #include <unistd.h>
> #include <stdio.h>
>
> int main(void)
> {
>         pid_t pid = vfork();
>         if ( pid > 0 )
>         {
>                 printf("I'm chield.\n");
>                 _exit(0);
>         }
>         else if ( pid == 0 )
>         {
>                 printf("I'm parent");
>         }

You've got these swapped. pid == 0 means child, > 0 means parent (so that  
it directly has the PID of its child and can later call waitpid()).

You later wrote you've issues with the path; does the same happen if you  
use "fork" rather than "vfork"?  vfork()ed child processes must not do  
anything but modify a variable of type pid_t, call _exit() or exec*().

-- 
Matthias Andree

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