Nice. One suggestion:

# change:
print $buffer[0] if /$pat/;

# to:
print $buffer[0] if /\Q$pat\E/o;
[download]

The \Q and \E presume that $pat is just a string, not a regex. So you would want to escape any special characters (like '.' or '+' ) and the o tells Perl that $pat isn't going to change in the loop, so it won't keep recompiling the pattern.