I'm presently using PHP 5.3.8 and I am unable to can get on with php.ini.

I absolutely must let the PHP directive "short_open_tag" to Onto it because I make use of a great Content management systems that utilizes just the <? ?>.

I attempted make it possible for it with my Apache .htaccess (php_value short_open_tag 1), but adding this will cause Apache to continually problem 500 errors.

N.B. My server works together with PHP in CGI mode.

You need to have the ability to use...

ini_set('short_open_tag', '1');

Based on the documentation (PHP_INI_ALL).

Hopefully this excellent Content management systems includes a front controller where one can replace the very first <? with <?php, after which use ini_set().

If PHP is running like a CGI, then you definitely cannot make use of a .htaccess file to create PHP flags, this only works if PHP is definitely an Apache module.

You should use ini_set to create this flag from the PHP script, but this will not assist you to since ini_set only affects the presently running PHP process and does not persist.

Your only option might be to request your host enable short tags in php.ini, or edit each PHP file to exchange