-open my $fh, "-|", "varnishncsa -F '%{%s}t %U %q tffb=%{Varnish:time_firstbyte}x' -q 'ReqURL ~ \"^/analysis.pl\"'"
+my $url = $ARGV[0] // "/analysis.pl"; # Technically an URL regex, not an URL.
+my $port = $ARGV[1] // 5000;
+
+open my $fh, "-|", "varnishncsa -F '%{%s}t %U %q tffb=%{Varnish:time_firstbyte}x' -q 'ReqURL ~ \"^$url\"'"