Anonymous Monk,

=~ says: matches regex
!~ says: does not match regex

See perldoc perlop for more info. Either of the following should work:

print "yahoo!\n" if grep /^#/ , @lines;
# or
for ( @lines ) {
    if ( /^#/ ) {
        print "yahoo!\n";
        last;
    }
}
[download]

The latter stopping on first match.

Cheers - LR