#!/usr/local/bin/perl
use CGI ':standard'; 

print "Content-type: text/html\n\n"; 

open (FILE,"writeline.cgi");
open (TEMP,">external_file.txt.tmp");

my $i = 0;

while (<FILE>)
{ 
    if ($i == 13){ 
     
        $_ = "\$pageFile=\"webpage.html\";\n" if ($i == 13);
    } 

    print TEMP $_; 

} continue { 
    $i++; 
}

close FILE;
close TEMP;

unlink ("write.cgi"); 
rename ("external_file.txt.tmp","writeline.cgi");