Seite drucken - system() - return value always -1

Titel: system() - return value always -1
Beitrag von: Bob B am 04 Dezember 2016, 15:52:59

Snippet from my .pm :

        @cmd = ("sudo", "/opt/energenie/RobBoilerControl.py", "ch", "on"); #MUST use sudo - no other method works reliably to access /dev/mem
        $retVal = system(@cmd);
        Log 3, "retVal = $retVal";
        #system(@cmd) == 0 or Log 3, "system @cmd failed: " ; # test fails - system always returns -1 ?
        #or die "system @cmd failed: $?";

system(@cmd) works fine but always returns -1 instead of 0. (I have since seen reference to this behaviour in fhem forum somewhere but have lost it now.)
I want that return value! The script's output end's up in the log very nicely and I don't want to rewrite it so as to run it with backticks but that's all I can think of right now.
Any thoughts please?

Titel: Antw:system() - return value always -1
Beitrag von: rudolfkoenig am 05 Dezember 2016, 13:15:38

I get -1 if perl cannot execute the program.
I tried it with test.x:

Code Auswählen

#!/bin/sh
echo hallo
exit 7

and

Code Auswählen

perl -e 'my @a = ("test.x"); my $v = system(@a); printf "%04x\n",$v'
which returns

Zitathallo
0700

Titel: Antw:system() - return value always -1
Beitrag von: Bob B am 05 Dezember 2016, 17:24:57

Thanks Rudolf.

Running perl directly is no problem; I get exactly the same behaviour with system() as you do - with correct status returns.

Running system() inside fhem (99_RobBoilerControl.pm in my case) it always returns -1 even though the associated python script succeeds.

I'm too much of a noob in fhem and perl to guess what is going wrong.

Bob

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FHEM => English Corner => Thema gestartet von: Bob B am 04 Dezember 2016, 15:52:59