=head1 NAME
-perlfaq9 - Networking ($Revision: 1.2 $, $Date: 2001/09/28 06:40:07 $)
+perlfaq9 - Networking ($Revision: 1.7 $, $Date: 2002/01/28 04:17:27 $)
=head1 DESCRIPTION
=head2 My CGI script runs from the command line but not the browser. (500 Server Error)
-If you can demonstrate that you've read the FAQs and that
+Several things could be wrong. You can go through the "Troubleshooting
+Perl CGI scripts" guide at
+
+ http://www.perl.org/troubleshooting_CGI.html
+
+If, after that, you can demonstrate that you've read the FAQs and that
your problem isn't something simple that can be easily answered, you'll
probably receive a courteous and useful reply to your question if you
post it on comp.infosystems.www.authoring.cgi (if it's something to do
If you want a more complete solution, see the 3-stage striphtml
program in
-http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/striphtml.gz
+http://www.cpan.org/authors/Tom_Christiansen/scripts/striphtml.gz
.
Here are some tricky cases that you should think about when picking
=head2 How do I extract URLs?
-A quick but imperfect approach is
+You can easily extract all sorts of URLs from HTML with
+C<HTML::SimpleLinkExtor> which handles anchors, images, objects,
+frames, and many other tags that can contain a URL. If you need
+anything more complex, you can create your own subclass of
+C<HTML::LinkExtor> or C<HTML::Parser>. You might even use
+C<HTML::SimpleLinkExtor> as an example for something specifically
+suited to your needs.
+
+Less complete solutions involving regular expressions can save
+you a lot of processing time if you know that the input is simple. One
+solution from Tom Christiansen runs 100 times faster than most
+module based approaches but only extracts URLs from anchors where the first
+attribute is HREF and there are no other attributes.
+
+ #!/usr/bin/perl -n00
+ # qxurl - tchrist@perl.com
+ print "$2\n" while m{
+ < \s*
+ A \s+ HREF \s* = \s* (["']) (.*?) \1
+ \s* >
+ }gsix;
- #!/usr/bin/perl -n00
- # qxurl - tchrist@perl.com
- print "$2\n" while m{
- < \s*
- A \s+ HREF \s* = \s* (["']) (.*?) \1
- \s* >
- }gsix;
-
-This version does not adjust relative URLs, understand alternate
-bases, deal with HTML comments, deal with HREF and NAME attributes
-in the same tag, understand extra qualifiers like TARGET, or accept
-URLs themselves as arguments. It also runs about 100x faster than a
-more "complete" solution using the LWP suite of modules, such as the
-http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/xurl.gz program.
=head2 How do I download a file from the user's machine? How do I open a file on another machine?
use CGI qw/:standard/;
- my $url = 'http://www.perl.com/CPAN/';
+ my $url = 'http://www.cpan.org/';
print redirect($url);
C</^[\w.-]+\@(?:[\w-]+\.)+\w+$/>. It's a very bad idea. However,
this also throws out many valid ones, and says nothing about
potential deliverability, so it is not suggested. Instead, see
-http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/ckaddr.gz,
+http://www.cpan.org/authors/Tom_Christiansen/scripts/ckaddr.gz,
which actually checks against the full RFC spec (except for nested
comments), looks for addresses you may not wish to accept mail to
(say, Bill Clinton or your postmaster), and then makes sure that the
The Mail::Internet module uses Net::SMTP which is less Unix-centric than
Mail::Mailer, but less reliable. Avoid raw SMTP commands. There
are many reasons to use a mail transport agent like sendmail. These
-include queueing, MX records, and security.
+include queuing, MX records, and security.
=head2 How do I use MIME to make an attachment to a mail message?
=head1 AUTHOR AND COPYRIGHT
-Copyright (c) 1997-1999 Tom Christiansen and Nathan Torkington.
+Copyright (c) 1997-2002 Tom Christiansen and Nathan Torkington.
All rights reserved.
This documentation is free; you can redistribute it and/or modify it