How do I change '|' to '-' in HTML page title?
I would have used existing $head_title_array variable like this:

&lt;title&gt;&lt;?php print $head_title_array['name'] . ' - ' . $head_title_array['title']; ?&gt;&lt;/title&gt;


Reference: html.tpl.php

You can also do this with the Metatag module.