#/usr/bin/perl -pi.bak
$count++ if s/^go/\//;

END { print STDERR "There were $count lines starting with 'go' in the file\n"; }

##</code><code>##

open FILE, "< $file" or die "Can't open input file: $!\n";
open OUT, "> '$file.new'" or die "Can't open output file: $!\n";
while (<FILE>) { 
    $count++ if s/^go/\//;
    print OUT;
}
close OUT;
close FILE;
print STDERR "There were $count lines starting with 'go' in the file\n";
rename $file, "$file.bak";  # make backup copy
rename "$file.new", $file;  # overwrite original file