$ENV{FOO} = 'foo';

##</code><code>##

use strict;
use warnings;

open RD, '<', 'foo.bat' or die $!;
while(<RD>) {
  if($_ =~ /set\s/i) {
    my @v = split /=/, $_;
    my $n = (split /\s/, $v[0])[-1];
    $ENV{$n} = $v[1];
    print "\$ENV{$n} : $ENV{$n}\n";
  }
}

my @progname_output = `progname l`;