i have trouble with my server that is running ubuntu (debian) linux and apache 2.2/php 5.2

because this is mainly an effective server, display_errors is switched OFF within the php.ini

for development reasons, i wish to enable these error confirming stuff for several domain names. however when i set

php_flag display_errors on

within the .htaccess file from the test-domain, it really wont work :( so i must set display_errors within the php.ini which affects ALL websites around the server... just how can is placed this in your area for just one domain?

You can't provide PHP directives within an .htaccess file unless of course PHP runs as Apache module. Would be that the situation? If that's the case, first make certain the file is really being read. A fast test you should do is to create a syntax error purposely within the .htaccess file: your website should return a 500 error message. If you're running PHP as CGI, you most likely possess a custom php.ini file somewhere for every user.

Finally, you are able to enable error confirming inside a per-application basis. Just add this code on the top:

<?php

ini_set('display_errors', 1);
error_reporting(E_ALL);

?>

Is [cde] enabled inside your vhost? Whether it's set to 'None', then Apache will absolutely ignore .htaccess files.