OpenEuphoria

RE: system_exec()

• Posted by Al Getz <Xaxo at aol.com> Jul 13, 2003
• 467 views

jbrown105 at speedymail.org wrote:
> 
> 
> On Sun, Jul 13, 2003 at 06:07:17PM +0200, Juergen Luethje wrote:
> > 
> > 
> > Hello again Al, you wrote:
> > 
> > > Juergen Luethje wrote:
> > >>
> > >>
> > >> Hi Jim, you wrote:
> > >>
> > >>> On Fri, Jul 11, 2003 at 11:49:25PM +0200, Juergen Luethje wrote:
> > >>
> > >> <big snip>
> > >>
> > >>>> I'll try to summarize (S: run a child process  sychnronously,
> > >>>>                        A: run a child process asychnronously):
> > >> Should be "a/synchronously", of course.   -------^^^^^^^^^^^^^^
> > >>
> > >>>>
> > >>>>          |    Euphoria command
> > >>>>          |
> > >>>>          | system() | system_exec()
> > >>>> ---------+----------+--------------
> > >>>> DOS      |    S     |      S
> > >>>> ---------+----------+--------------
> > >>>> Windows  |    A     |      S
> > >>>> ---------+----------+--------------
> > >>>> Linux    |    S     |      S
> > >>>> ---------+----------+--------------
> > >>>> FreeBSD  |    S     |      S
> > >>>>
> > >>>>
> > >>>> Is this the bottom line?
> > >>>
> > >>> I thought that system() under Windows would be 'S' not 'A' ... but
> > >>> then again I probably wouldn't know...
> > >>
> > >> I only can say that under Windows 98, 'A' is correct for system().
> > >> I don't think it's likely, that other Windows versions behave different
> > >> regarding this point.
> > >> Interestingly -- provided this litte table is correct --, the 'A' for
> > >> Windows is the exception. The table is almost contrary to what I had
> > >> expected. 
> > >>
> > >> Anyway, the question of practical importance for me at the moment was
> > >> the behaviour of system_exec() under Windows, and that seems pretty
> > >> clear now.
> > >> Thanks again to all, who helped me.
> > >>
> > >> Best regards,
> > >>    Juergen
> > >
> > >
> > > Hello again,
> > >
> > > It looks to me that System() is synchronous.  If it werent
> > > my EuViewer wouldnt work correctly.
> > 
> > Hmm... I'd like to have a look at it, but I didn't find anything, when
> > I searched for "EuViewer" in the RDS archieve.
> 
> > 
> > > When i said it only worked with a '2' as second argument,
> > > it was actually a much older version of Euphoria.
> > > Apparently, either a 0 or a 2 works ok with the viewer (v2.4 tested).
> > > This means it's synchronous.  I didnt try '1' because i dont want
> > > a beep 
> > 
> > OK, then we'll only use 0 or 2 as second parameter for system(). 
> 
> 0, 1, and 2 all have the same effect ... they are all synchronous.
> 
> > 
> > Please try the following code on Windows:
> >    system("calc", 2)
> >    puts(1, "Hi there.")
> >    if getc(0) then end if
> > 
> > At least on Windows 98, the console window saying "Hi there!" pops up,
> > although the calculator is still running.
> > That's why I thought, that on Windows system() is asynchronous.
> 
> Thats a special property of Windows GUI programs. Not sure why M$
> choose to do it like that tho.
> 
> Doing system("kcalc &", 2) on a linux/freebsd system via exu would have
> system act async as well (since the '&' tells it to run in the 
> background
> instead of the foreground).
> 
> jbrown
> 
> > 
> > Best regards,
> >    Juergen
> > 
> > -- 
> >  /"\  ASCII ribbon campain  |    |\      _,,,---,,_
<snip>


Could be they didnt want programs hanging for no good reason.
Would be interesting to find out more about this though...
Could it be it only waits for programs that return a value?


Take care for now,
Al