This is probably a long shot, look at the code below. In it, the $_ variables are apparently tripping over each other.

#!/usr/local/perl510/bin/perl
use strict;
use warnings;
use Data::Dumper;
use IPC::Open3;

my @plist = ( '/usr/bin/cat /etc/motd' );

sub ccmexec_nodie {
    my $command = $_[0];
      
    my ($mystdin,$mystdout,$mystderr);
    my $pid = open3($mystdin,$mystdout,$mystderr,$command);
   
    my $myresult = "";
    while(<$mystdout>){
        $myresult = "$myresult$_";
        }
   
    return $myresult;
    }

print 'Before: ', Dumper \@plist;
foreach  ( @plist ) {
    print Dumper ccmexec_nodie $_;
    }
print 'After:  ', Dumper \@plist;
[download]

and the output it generates:

Before: $VAR1 = [
          '/usr/bin/cat /etc/motd'
        ];
$VAR1 = 'Sun Microsystems Inc.  SunOS 5.10      Generic January 2005
';
After:  $VAR1 = [
          undef
        ];
[download]

Now, this does NOT duplicate your problem! But, maybe you are running into something similar? Or assigning values to aliases like @_ and the values it contains (the $_[$index] variables). Or modifying @plist from within a for/foreach loop? I get the sense you are tripping over something along those lines.

In that light, I would suggest you eliminate all use of default variables like $_, make sure you are always using a copy of a variable, etc. and see if that changes anything. Something like:

#!/usr/local/perl510/bin/perl
use strict;
use warnings;
use Data::Dumper;
use IPC::Open3;

my @plist = ( '/usr/bin/cat /etc/motd' );

sub ccmexec_nodie {
    my( $command )= @_;
      
    my ($mystdin,$mystdout,$mystderr);
    my $pid = open3($mystdin,$mystdout,$mystderr,$command);
   
    my $myresult = "";
    while(my $in=<$mystdout>){
        $myresult .= $in;
        }
   
    return $myresult;
    }

print 'Before: ', Dumper \@plist;
foreach my $cmd ( @plist ) {
    print Dumper ccmexec_nodie $cmd;
    }
print 'After:  ', Dumper \@plist;
[download]

Good luck!!

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