Replace pieces in long text

Hi, I have a system written in PHP, where users can manage their own template-file. I'm using ETS (http://ets.sourceforge.net) to parse the templates. And I want to have a ETS-var added to the template every time a user modifies his template. {/main} must be replaced with {disclaimer}{/main} and then saved. This is what i've done so far, but it won't work :( $content = str_replace("\{disclaimer\}\{/main\}", "\{/main\}", $content); $content = str_replace("\{/main\}", "\{disclaimer\}\{/main\}", $content); Could anybody help? Thanks, Thijs