Re: ⎕FIO non Zero Return Code related to ⎕FX

[Hans-Peter Sorge]

Hello Jüregen,

I now have executed like code multiple times from a function.
Only for the last execution returns -10.
May be some race condition.

Thank You for the explanation.

Best Regards
Hans-Peter


Am 30.10.20 um 14:20 schrieb Dr. Jürgen Sauermann:
> Hi Hans-Peter,
>
> I have checked the ⎕FIO code and it looks correct to me.
>
> In your first example I get the result that you are expecting:
>
> *      Command←'echo "sad x asds" | sed "s/x/y/g"'**
> **      Handle←⎕FIO[24] Command**
> **      D←⎕FIO[6] Handle**
> **      ZN←⎕UCS D**
> **      ZN **
> **sad y asds**
> **
> ****
> **      ⎕FIO[25] Handle**
> **0*
>
> Having that said, consider this:
>
> The error code *-10* means *ECHILD*:
>
> *eedjsa@server68:~/projects/juergen/apl-1.8/src$ errno ECHILD**
> **ECHILD 10 No child processes**
> *
> According to *man pclose*:
>
>        If pclose() cannot obtain the child status, errno is set to 
> ECHILD.
>
> I suppose this is what happens here. For some reasons (beyond what GNU 
> APL can do)
> either your shell or your operating system is unable to determine the 
> exit status of your process
> (i.e. of the Command that you are executing). Maybe this is related to 
> using a pipe, but maybe not.
>
> Please keep in mind that the shell which popen() aka. ⎕FIO[24] uses 
> could be different
> different then the shell from the shell that has started apl. In my 
> case the shell that has
> started apl was *bash* while popen uses *sh*. For that reason I get a 
> syntax error with you
>  second example (*sh* does not know <<<) while you don't. That also 
> points to shell
> differences.
>
> A work-around for this problem might be to return an explicit exit 
> code from your command:
>
> *      Command←'echo "sad x asds" | sed "s/x/y/g" && exit 3'**
> **      ⎕UCS (⎕FIO[6] Handle←⎕FIO[24] Command) ◊ ⎕FIO[25] Handle**
> **sad y asds**
> **
> **768**
> *
> The *728* above is the exit code *3* shifted 8 bits. This is only to 
> demonstrate the shift,
> normally you would use 0 instead of 3.
>
> Hope this helps,
> Jürgen
>
>
> On 10/29/20 9:06 PM, Hans-Peter Sorge wrote:
> > Hi,
> >
> > the Command is being correctly executed, the return codes are -10
> >
> >       Command←'echo "sad x asds" | sed "s/x/y/g"'
> >       Handle←⎕FIO[24] Command
> >       D←⎕FIO[6] Handle
> >       ZN←⎕UCS D
> >       ZN
> > sad y asds
> >
> >       ⎕FIO[25] Handle
> > ¯10
> >
> >       Command←'sed "s/x/y/g" <<< "sad x asds"'
> >       Handle←⎕FIO[24] Command
> >        D←⎕FIO[6] Handle
> >       ZN←⎕UCS D
> >       ZN
> > sad y asds
> >
> >       ⎕FIO[25] Handle
> > ¯10
> >
> >
> > However starting a new apl session gives:
> >
> >       Command←'sed "s/x/y/g" <<< "sad x asds"'
> >       Handle←⎕FIO[24] Command
> >       D←⎕FIO[6] Handle
> >       ZN←⎕UCS D
> >       ⎕FIO[25] Handle
> > 0
> >
> >       'libedif2.so' ⎕FX 'E'
> > E
> >
> >       Command←'sed "s/x/y/g" <<< "sad x asds"'
> >       Handle←⎕FIO[24] Command
> >       D←⎕FIO[6] Handle
> >       ZN←⎕UCS D
> >       ⎕FIO[25] Handle
> > ¯10
> >
> > I have not checked other native functions.
> >
> > Regards
> > Hans-Peter