Depending on Linux distribution, Apache web server is normally set to run as the user nobody, www-data or apache. This among other is for security reason, as the default user normally doesn’t have shell login and is normally set to very limited permission.

If for some reason you need to run Apache as different user and group, the trick is to just change the User and Group directive in Apache configuration file, which normally is the /etc/apache2/httpd.conf as the following;

User nobody
Group nobody

To make the changes to take effect, the Apache webserver needs to be restarted first, normally with the following init script;

# /etc/init.d/apache2 restart