Select Code to Download

   defined       #same as defined($_)
   print         #same as print STDOUT $_
   /\sjackson$/  #same as $_ =~ /\sjackson$/

  @only_defined = grep { defined($_) } @somearray;
  %hash_defined = map { $_ => 1 } @only_defined;
...
  #and since $_ is the default argument, you can also write
  @only_defined = grep { defined } @somearray;
  @only_begins_with_a = grep { /^a/ } @somearray;

  while (<STDIN>) {
    chomp              # same as chomp $_
    if (/^#/) {....}   # same as if ($_ =~ /^#/) { ....}
  }

#Note this code still won't work - see sherm's explanation below.
...
     if($name =~ "jackson")
     print $name . "\n";     #sic - should be { print $name . "\n" }
 }

  while (my $line = <STDIN>) {
    chomp $line;
    if ($line =~ /^#/) {....}
  }