open( RTR, "$rtrlist" ) || die "Can't open $rtrlist file";
...
open( LOG, ">$workingdir/RESULT.TXT" )|| die "Can't open $workingdir/RESULT.TXT file";
...
$rtr = `$snmpget .1.3.6.1.4.1.9.2.1.3.0 $snmpro[0] $rtr` or print "hostname failed: $!\n";
...
	$rtr = `$snmpget .1.3.6.1.4.1.9.2.1.3.0 $snmpro[1] $rtr` or print "Host not responding to $snmpro[1]\n";

##</code><code>##

printf "  Router\t\t Location\t\t\tContact\t\t  Serial\n";
printf LOG "  Router\t\t; Location\t\t\t;Contact\t\t  ;Serial\n";

##</code><code>##

foreach (<RTR>) {
    chomp( $rtr = "$_" );