7 unix commands

<html>
<head><title>Unix Command</title></head>
<body>
<form method=GET action="http://localhost/cgi-bin/7a.pl" >
<center><br><h1>ENTER UNIX COMMAND TO BE EXECUTED</h1>
<input type="text" name="msg">
<input type="submit" value="CLICKME">
</form>
</body>
</html>

7a.pl
#!/usr/bin/perl
use CGI':standard';
print "content-type:text/html";
$c=param('msg');
system($c);
exit(0);

7b.pl
#!/usr/bin/perl
print "content-type:text/html ";
$count_file="/var/www/cgi-bin/ru.txt";
if(open(FILE,'<'.$count_file))
{
        $no_accesses=<FILE>;
        close(FILE);
        if(open(FILE,'>'.$count_file))
        {
            $no_accesses++;
            print FILE $no_accesses;
            close(FILE);
            print "no. of visitors:",$no_accesses;
        }
        else
        {
            print "[can't write to data file]";
}
}
else
{
        print "[sorry]";
}
exit(0);