1. The use strict pragma is a great tool, particularly if you are just learning. It catches a lot of silly errors. Similarly for use warnings. See Use strict warnings and diagnostics or die for a discussion why.

2. Rather than two-argument open w/ bareword filehandle, it's probably a better idea to use three-argument open with an indirect handles. See perlopentut for lots of gory detail. You should also check if the open actually succeeded with an or die clause. In this case, your opens might look like:

   open($Definedlist, '<', $name) or die "Open failed on $name: $!";     
   +    # opens the file and places the contents into Namelist
   
   open($BigNamelist, '<', $newName) or die "Open failed on $name: $!";  
   +  # opens the second file and places the contents into Newlist
   [download]

3. Your close statements are being run against non-existent filehandles. Using indirect filehandles with strict would have caught this error. Also, you don't usually need to close indirect filehandles since the close automatically when they go out of scope.

4. There is no Perl egrep built-in (function? method? sub? I'm never sure what to call things). There is a grep. This particular task is also a FAQ. See How can I tell whether a certain element is contained in a list or array?

You should probably pick up an into text to help you get started. You can't beat the price of Beginning Perl, though it's pretty out of date. See a whole list of books at http://learn.perl.org/books/. Anonymous Monk's suggestion of reading perlintro is also a good idea.

HTH.

Thank you very much for your wisdom i will indeed buy these books perl seems a very fun language

You basically have two possible strategies, choosing one or the other will depend one several factors, the main ones being the relative size of the the two lists and how well defined the names of the first list appear in the second one.

Suppose your list of names is very short and your document quite large. For example, the document is the King James Bible and the list of names has only four names : (God, David, Mary, Jesus). You will probably want to read each line of the document and use a regular expression to print out each line that matches the regex. Something like this:

# ...
while (<$INPUT>) {
     print $OUT if /God/ or /David/ or /Mary/ or /Jesus/;
     # could also be written: print $OUT if /God|David|Mary|Jesus/;
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The opposite case is when your name list is very large (say for example 10,000 words or more) and the document quite small. In this case, it is probably better to first load your name list into a hash, and then to read the document line by line, split each line into words and check if the word exists in the hash. Something like this (untested):

IN: while (<$INPUT>) {
     my @words = split /\b/, $_;
     foreach my $word (@words) {
          print $_ and next IN if exists $name_hash{$word};
     }
}
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Quite possibly you don't even care of speed, because it is so fast anyway, then chose the easiest algorithm (probably the first one).