You need to convert the non-HTML (the url) into HTML *before* inserting it into the document.

use HTML::Entities qw( encode_entities );

my $url = 'http://www.somedomain.com/index.cgi?page=home&var=1&no=2&so
+=forth&so=on';

my $h_url = encode_entities($url);
print(qq{...<a href="$h_url">...</a>...};
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Using Template-Toolkit, you'd use something like

...<a href="[% url | html %]">...</a>...
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