...
 # $addr is the actual subnet, e.g. "192.168.1.0"
 ...
 my $output = qx{nmap -sP ${addr}/24};
 my @nodes= $output =~ /(?<=\s)c\w+\b/g;

##</code><code>##

 ... 
 print header('text/html');
 print h1('Local Network: '. $addr . '/24');
 print map "$_ appears to be up<br />", @hosts
 ...

##</code><code>##

 ...
 my ($exe, $cmd) = ('/usr/bin/rsh', 'ps -fl r -u username');
 my $cnt = 0;

 for my $node ( sort @nodes ) {
   my @res = grep !(/$cmd/ || /STIME/), split /[\n\r]+/, qx{$exe $node $cmd};
   my $nproc = scalar @res;   # how many processes

   if( $nproc ) {
      print map
         "Do " . "some ". "formatting of " . "ps -fl output here!",
           @res
   }
  ...
  ++$cnt
  ...