sub kill_process
{
    print "Kill processes for the user? (y or n)?\n";
    my $ans = <>;

    while ($ans =~ /^Y/i)
    {
        print "Enter pid to kill:\n";
        my $pid = <>;
        chomp $pid;

        if (is_valid($pid))
        {
            `kill $pid`;
            print "Process $pid killed\n";
        }
        else
        {
            print "Process $pid is invalid\n";
        }

        print "Kill more processes for the user? (y or n)?\n";
        my $ans = <>;
    }
}