Re^4: Best way to kill a child process

in reply to Re^3: Best way to kill a child process
in thread Best way to kill a child process

We both agree on the main issue here: ...

I think we also do agree on the potential side issues related to portability :)

Just for the record: a quick peek into the sources turned up this (in util.c):

#if defined(SA_NOCLDWAIT) && !defined(BSDish) /* See [perl #18849] */
    if (signo == SIGCHLD && handler == (Sighandler_t) SIG_IGN)
        act.sa_flags |= SA_NOCLDWAIT;
#endif
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and the referenced #18849 is an interesting read. Essentially, the issue seems to revolve around if and how the sigaction() flag SA_NOCLDWAIT is implemented, i.e. its interactions with the varieties of the wait calls (wait(), wait4(), waitpid() ). And - as I read it - the upshot of it is that if SA_NOCLDWAIT could lead to problems, it isn't needed anyway — which is why the current implemention "mostly" works...

Anyhow, I've used $SIG{CHLD} = 'IGNORE' on quite a few versions and brands of Unix-ish systems (AIX, HP-UX, IRIX, Linux, Solaris) and haven't had any issues with it yet (which is not to say there might not be potential problems on some other platform, of course).

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