use strict;

my %logHash;
my $ctr=0;
my $diff=0;
sub compare{
    my($log, $olog) = @_;
    open(XR, "$log")||die;
        while(<XR>){
            $logHash{$_}=1;
        }
    close(XR);
    
    open(OXR, "$olog")||die;
        while(<OXR>){
        $diff=1 unless defined($logHash{$_});
            }
    close(OXR);
return $diff;
}

system('latex test.tex');
system ("copy test.log test-old.log");
system('latex test.tex');

while(compare("test.log","test-old.log")){
        system ("copy test.log test-old.log");
        system('latex test.tex');
}