If this is the exact code you used on your server, then the error is because if ($url=~list$r=1) is not valid Perl code. Help for such stuff can be found in many a way :

• Have a look at /ver/log/httpd/errors.log or whatever your httpd logfiles are called
• use CGI::Carp
• Test your scripts outside of your browser; using CGI.pm greatly eases offline testing.