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

[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