I usually just take an array of "required" field names and loop through it and any that are blank get added to a scalar that contains an HTML list, like so:

use CGI;

my $q = new CGI;

my $missed;
my @required = qw(name address phone email);
for (@required) {
    $missed .= "<li>$_</li>\n" if $q->param($_) eq "";
}
do {
    print "Content-type: text/html\n\n";
    print qq~
You forgot to fill in the following required fields:
<ul>$missed</ul>
~;
} if $missed;
[download]

(Use this link until vroom finishes fixing the other link syntax)

Now, I think you probably do not want to use a redirect. Send the form back, with the fields populated with what the user did enter. A co-worker of mine likes to put some kind of arrow graphic next to each field requiring the user's attention. You could also give empty fields a boldface label or use some other device to draw attention to the empty fields. If you don't detest javascript, you could even pop up a dialog telling the user what just happened, with instructions on how to fix it.

Good luck...

Russ
Brainbench 'Most Valuable Professional' for Perl

use CGI;
$q = new CGI;

if ($q->param('foo')) {
    #do stuff if has stuff in field
}else {
   print $q->redirect('http://www.foo.bar');
}
[download]

if ($q->param('foo')) {
    #do stuff if has stuff in field
}else {
   my $bar = $q->param('bar'); #should test this too.
   print $q->header;
   print "foo was empty please try again";
   print "your html stuff here again";
   #this next line keeps the info already provided.
   print "<input type=text name=bar value=$bar>";

}
[download]

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