The only trick is letting perl know where the Vars() is coming from. As kwaping, showed, you can do that by using the CGI object. You can also import it, as the POD says with ":cgi-lib"

use CGI qw(header start_html Vars pre);
use Data::Dumper;

print
    header(),
    start_html();

my $ref = Vars();
print pre( Dumper( $ref ) );

# or just fully qualify it                                            
+                 
use CGI ":standard";

# ...                                                                 
+                 
my %params = CGI::Vars();

print pre( Dumper( \%params ) );

# or what the POD suggests
use CGI qw(:standard :cgi-lib);

print pre( Dumper( [ Vars() ] ) );
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Thanks. The Data::Dumper bits threw me at first, but since I don't have that module, I'll just ignore those lines.

I assume (dangerous, I know), that I can print the key value pairs with:

while (my ($variable_name, $variable_value ) = each %params) {
    print "Variable name = $variable_name/n Variable value = $variable
+_value\n\n";
}
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Yes?

UPDATE
my test/understanding code now looks like this:

#!/usr/bin/perl -wT
# tools.cgi

use strict;
use CGI qw(header start_html Vars pre);
use CGI::Carp qw(fatalsToBrowser);

print header();

print "These are the values submitted:\n\n";
my %params = Vars();

my $count = keys %params;
print $count; 

while (my ($variable_name, $variable_value ) = each %params) {
    print "Variable name = $variable_name/n Variable value = $variable
+_value\n\n";
}
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I tried
use CGI qw(:standard :cgi-lib); and
use CGI ":standard"; and both of those threw errors and wouldn't execute. But this third option will run, but gives an output of
These are the values submitted: 0
even though I know there are values. I passed and printed them successfully with

foreach $sri_variable( $cgi->param){
    print "$sri_variable:\n";
    foreach $variable_value( $cgi->param($sri_variable) ){
        print "  $variable_value\n";
    }
}
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Sounds like you're doing something weird in there; you should probably check your error logs or do the full use CGI::Carp qw(fatalsToBrowser warningsToBrowser);. All those examples should work fine.

Another thing you might consider is the Vars() idiom is a little strange today. There is no reason to avoid the param() function in favor of it. Your code above becomes (with a little HTML formatting help):

print '<ul>';
for my $sri_variable( param() ) {
    print '<li>', $sri_variable;
    print '<ul>';
    for my $variable_value( param($sri_variable) ){
        print li($variable_value);
    }
    print '</ul></li>';
}
print '</ul>';
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Make sure to use strict; use warnings; too. It looks like you're not. (update: fixed bad HTML nesting.)

I read something about using use CGI ':cgi-lib'; instead of use CGI qw(:standard) to be able to get the parameter list as a hash using Vars, but I don't understand that.

But in your code, you have:

use CGI qw(:standard :cgi);

Try changing it to:

use CGI ':cgi-lib';

Update: I should probably explain what this actually does... see use. Basically, arguments after the package name to 'use' are passed in as arguments to import ... items starting with a colon are calls to load specific sets of functions, as opposed to a single function name. You may want to also read up on Exporter, although CGI doesn't actually use it.

Thanks for the info on use. I had had use CGI ':cgi-lib'; in my code before I posed the question, but it wasn't working so I went back to the code I was used to.

#!/usr/bin/perl

# the usual suspects
use warnings;
use strict;

# CPAN modules
use CGI;

# create objects
my $cgi = CGI->new;

# read in form data
my %form_data = $cgi->Vars;

# output
print $form_data{'parameter_name_here'};
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Thanks, but isn't that in OO style? Maybe I'm really confused, but I was under the impression that OO used the -> while function-oriented (which I am trying to understand) does not.

Aside: I do not use strict; in my code because no matter what I've tried, I can't get anything to run with that in my scripts on the server set up I have. My unix admins tell me something is wrong with the perl install, but they don't know how to fix it... But I'm soon to get a new web server (woohoo, no more netscape server) with fresh installs of everything (woohoo, no more perl 5.004) so hopefully that will get fixed.