• 1a. /l/ says if there is an 'l' in $_ return true. This means that if you type ' l ' ('l' with some spaces) it'll still match. It will also match on 'list', 'look' and 'isn't that a nice whale over there?'. Personally I'd have done:

  s/\s//;   # remove all whitespace from $_
  if($_ eq "l") { entry_list(); }
  elsif($_ eq "a") {  addentry();}   #etc
  [download]

  $_ is equivalent to your $option.
• 1b. &s can be left off subroutine calls if the call is unambiguously a subroutine call. In this case (calling the subroutine with a pair of parens) the parens make it unambiguous. Calling the subroutine without parens but with & means that the subroutine gets given the contents of @_ as it's argument list. This is discouraged because it often frightens people.

  So there are these ways to call a subroutine (ignoring object methods):

  subroutine;          # doesn't pass strict.
  &subroutine;         # passes @_ as argument list
  
  &subroutine();       # looks weird, passes arguments in ()
  subroutine();        # generally preferred method
  [download]

• 2. || does mean "or" but they are not equivalent in associativity. Look at "perldoc perlop" for more information.
• 3. | allows alternation in regular expressions (those things between the //s). So yes, it does allow you to specify more than one option in an or-like fashion.
• 4. Looks like it probably clears the screen/terminal. Have you tried using it?
• 5. Yep. I think debiandude had originally intended tmp to be an array. my $tmp; has essentially the same effect. Of you can use my $tmp = undef;.

Hope it helps

jarich