need help exec command

Hi Gurus, I am using PHP 4.1.1, Postgresql 7.2 and Perl 5.6.0 on Linux. I want to execute a perl script throgh a PHP, which will take backup of the database after submit button on the PHP is clicked. I am using exec command, but as PHP runs as "nobody" user, it does not have access to Postgres database. So it creates a file of 0 byte. Can anybody tell me how to change user for execution of a particular PHP, or is there any other alternative. Thanking you in anticipation. Regards Umesh. ***************************** Umesh A. Deshmukh. Manas Solutions Pvt. Ltd. umesh@manas-solutions.com http://www.manas-solutions.com Ph. : 91+020+4006358,4223991/92 *****************************