While you can just download the PHP source and compile it yourself,
    using Debian's packaging system is the simplest and cleanest
    method of installing PHP. If you are not familiar with building
    software on Linux, this is the way to go.
   
    The first decision you need to make is whether you want to install
    Apache 1.3.x or Apache 2.x. The corresponding PHP packages are
    respectively named libapache-mod-php* and libapache2-mod-php*.
    The steps given below will use Apache 1.3.x.
    Please note that, as of this writing, there is no official
    Debian packages of PHP 5. Then the steps given below will install PHP 4.
   
    PHP is available in Debian as CGI or CLI flavour too, named respectively
    php4-cgi and php4-cli. If you need them, you'll just have to reproduce the
    following steps with the good package names.
    Another special package you'd want to install is php4-pear. It contains a
    minimal PEAR installation and the pear commandline
    utility.
   
    If you need more recent packages of PHP than the Debian's stable ones
    or if some PHP modules lacks the Debian official repository, perhaps
    you should take a look at http://www.apt-get.org/.
    One of the results found should be
    Dotdeb. This unofficial repository
    is maintained by Guillaume Plessis
    and contains Debian packages of the most recent versions of PHP 4 and PHP 5.
    To use it, just add the to following two lines to your
    /etc/apt/sources.lists and run apt-get
    update :
   
| Example 4-7. The two Dotdeb related lines | deb http://packages.dotdeb.org stable all
deb-src http://packages.dotdeb.org stable all | 
 | 
    The last thing to consider is whether your list of packages is up to date.
    If you have not updated it recently, you need to run apt-get update
    before anything else. This way, you will be using the most recent
    stable version of the Apache and PHP packages.
   
    Now that everything is in place, you can use the following example
    to install Apache and PHP:
   
| Example 4-8. Debian Install Example with Apache 1.3 | # apt-get install libapache-mod-php4 | 
 | 
    APT will automatically install the PHP 4 module for Apache 1.3, and all its
    dependencies and then activate it.  If you're not asked to restart Apache
    during the install process, you'll have to do it manually :
   
| Example 4-9. Stopping and starting Apache once PHP 4 is installed | # /etc/init.d/apache stop
# /etc/init.d/apache start | 
 | 
    In the last section, PHP was installed with only core modules.
    This may not be what you want and you will soon discover that you need
    more activated modules, like MySQL, cURL, GD, etc.
   
    When you compile PHP from source yourself, you need to activate modules
    via the configure command. With APT, you just have
    to install additional packages. They're all named 'php4-*' (or 'php5-*' if
    you installed PHP 5 from a third party repository).
   
| Example 4-10. Getting the list of PHP additional packages | 
    As you can see from the last output, there's a lot of PHP modules that
    you can install (excluding the php4-cgi, php4-cli or php4-pear special
    packages).
    Look at them closely and choose what you need. If you choose a module and
    you do not have the proper libraries, APT will automatically install all
    the dependencies for you.
   
    If you choose to add the MySQL, cURL and GD support to PHP the command
    will look something like this:
   
| Example 4-11. Install PHP with MySQL, cURL and GD | # apt-get install php4-mysql php4-curl php4-gd | 
 | 
    APT will automatically add the appropriate lines to your
    different php.ini (/etc/php4/apache/php.ini,
    /etc/php4/cgi/php.ini, etc).
   
| Example 4-12. These lines activate MySQL, cURL and GD into PHP | extension=mysql.so
extension=curl.so
extension=gd.so | 
 | 
    You'll only have to stop/start Apache as previously to activate the modules.