I made some changes but continue to get the same output, 'ERROR'. I know my code was kinda messy and i tried to clean it up by closing all the filehandles before reopening them and a few other changes. Heres what I have:

# Create a list of all possible IP addresses within subnet
open(ALLIP, ">allip.list") || die "Unable to create file: allip.list\n
+";
for ($i=0; $i<=20; $i++) {
        print ALLIP "$ip_subnet.$i\n";
}
close(ALLIP);
open(ALLIP, "allip.list") || die "Unable to open file: allip.list\n";
open(PINGALLIP, ">pingallip.list") || die "Unable to open file: pingal
+lip.list";
while (<ALLIP>) {
        system("ping $_ >pingallip.list") && "Unable to create file: p
+ingallip.l
ist";
chomp; }
close(ALLIP);
close(PINGALLIP);
open(OUTPUT, ">output.list");
open(PINGALLIP, "pingallip.list") || die "Unable to open file: pingall
+ip.list";
my $line = 0;
while (<PINGALLIP>) {
chomp;
        if ($_ =~ m/is alive/) {
                $line++;
                last;
        }

}
close(PINGALLIP);
        if ($line) {
                print OUTPUT "$_\n";
        } else {
                print "ERROR\n";
        }
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Any more help would be greatly appreciated. ~_^

~Zuinc