There should be absolutely no difference between

$ENV{'PLATFORM'}="abcdef";
[download]

and

$variable="PLATFORM";
$ENV{$variable}="abcdef";
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I'm noticing a lot of ugly style in your code, a lot of unnecessary code, but nothing that should stop it from working. The following works for me.

use strict;
 
if (@ARGV){
    print $ENV{PLATFORM}, $/;
    exit;
}
 
while(<DATA>){
    chomp;
    my ($variable, $value) = split '=';
    $ENV{$variable}=$value;
}
 
system("perl", $0, "test");
 
__DATA__
PLATFORM=abcdef
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In particular, you don't need to use "$variable", just $variable. You don't need to seek to the begining of a file handle you just opened. You don't need to chomp the components if you already chomped the variable they were split from. But none of that should really cause problems. Are you sure that your code is actually being run? That is, you've got the assignment to %ENV inside an if on your open. Do you have an else telling you if the open failed? Could you add code to print out $variable and $value when you're setting them to make sure they really have what you expect?