How to get return values of a forked process

[Ian]

On Jun 21, 1:54 pm, Ian Kelly <ian.g.ke... at gmail.com> wrote:
> On Tue, Jun 21, 2011 at 12:26 PM, Ian <ian.l... at rocketmail.com> wrote:
> > myForkedScript has code like this:
> > if fail:
> >    os._exit(1)
> > else:
> >    os._exit(os.EX_OK)
>
> > Is using os._exit() the correct way to get a return value back to the
> > main process?
>
> sys.exit() is the preferred way.
>
> > I thought the value 'n', passed in os._exit(n) would be the value I
> > get returned.  In the case of a failure, I get 256 returned rather
> > than 1.
>
> According to the docs, on Unix:
>
> """
> Wait for completion of a child process, and return a tuple containing
> its pid and exit status indication: a 16-bit number, whose low byte is
> the signal number that killed the process, and whose high byte is the
> exit status (if the signal number is zero); the high bit of the low
> byte is set if a core file was produced.
> """
>
> And on Windows:
>
> """
> Wait for completion of a process given by process handle pid, and
> return a tuple containing pid, and its exit status shifted left by 8
> bits (shifting makes cross-platform use of the function easier).
> """
>
> (256 >> 8) == 1
>
> However, I would advise using the subprocess module for this instead
> of the os module (which is just low-level wrappers around system
> calls).

Where did you find the Unix docs you pasted in?  I didn't find it in
the man pages.  Thank you.  Based on what you say, I will change my
os._exit() to sys.exit().