First thing: your post is unreadable. Try putting <code></code> tags around the route summary text. The other thing: post your solution to this and let us review it. It's not fair if we're doing all the work :)

You can match the desired text in many different ways as long as they're unique for the data lines you want matched. A simple regexp can match these active lines:

while (defined(my $line = <STDIN>)) {
    if ($line =~ /^inet\((\d+) active/) {
        print $line;
    }
}
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Output:

inet.0: 498154 destinations, 3436699 routes (498150 active, 0 holddown
+, 5 hidden)
inet.3: 10103 destinations, 10107 routes (10103 active, 0 holddown, 0 
+hidden)
inet6.0: 25299 destinations, 115803 routes (25299 active, 0 holddown, 
+0 hidden)
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