Apache can't install both PHP4 and PHP5 as a module at the same time, to make it parallel to install,
There is only one installation as a CGI and the other is installed as a Module. Generally I put PHP4
As a module installation, PHP5 is installed as CGI.
Because now my PHP code is mostly the legacy code of PHP4. In this way, we are the same
You can use PHP5 when you experimentally use it, and don't waste PHP4. The code has an upgrade process, waiting for our PHP4 code
After most rewritten as a PHP5 OO code, in exchange, install the php5 as a module, PHP4
Installed as a CGI.
However, CGI is not as efficient as the module installed as a module, and there are some restrictions.
For example, it is not possible to directly use the security of Apache's HTTP basic authentication.
(Apache's Http Basic Authentication Mechanism)
