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Installing Apache 2 and PHP 5 on Debian
Lately a lot of folks on #Apache have requested help with installation of Apache 2[.2] and PHP 5 on Debian-based systems.
Even though this is a rather straightforward process, we have so far neglected to document it. This page provides that documentation.
Preparing your system
Before getting started, you should prepare your system, and before preparing your system, you should prepare yourself. You should know: What do you want to achieve? What technology is best to achieve that goal? What constraints are there?
Now that you know that you want to create a website, using Apache 2, PHP 5 and MySQL, that your knowledge is your only constraint, and that this wiki will help you learn more, you can start preparing your system by typing [either as root, or prefixed with sudo]:
apt-get update
This will download the latest lists of packages, to make sure you install the current versions of the software.
Installing the Software
Installing the required packages is as straightforward as installing any other package on Debian; the trick is knowing what packages you need:
apt-get install apache2-mpm-prefork libapache2-mod-php5
This should actually suffice. Debian's package mangement system should now automatically chose the missing packages which need to be installed. If you're running the latest version of Debian [as of this writing: Etch], you might want to also install the latest [and best] version of apache, by explicitly specifying apache2.2-common in the above install command.
If you also need MySQL, adding php5-mysql and mysql-server-5.0, should do the rest of the magic.
After that install is complete, visiting _http://localhost/_ in your browser should prove that you now have a running web server.
Configuring PHP
As Debian is trying to be extra-friendly, it splits a single package up into all possible and impossible modules. In Apache's case those modules are called libapache2-mod-something and their configuration files are saved in /etc/apache2/mods-available. To enable a module, you'd type something like:
a2enmod php5
Which will simply symlink /etc/apache2/mods-available/php5.conf and /etc/apache2/mods-available/php5.load to /etc/apache2/mods-enabled/.
If you had php4 installed you might get the following error when restarting apache:
Forcing reload of web server (apache2)...apache2: Syntax error on line 185 of /etc/apache2/apache2.conf: Syntax error on line 1 of /etc/apache2/mods-enabled/php4.load: Cannot load /usr/lib/apache2/modules/libphp4.so into server: /usr/lib/apache2/modules/libphp4.so: cannot open shared object file: No such file or directory failed!
To solve this disable the php4 module:
a2dismod php4
For debian Lenny (5.0) and lower
You're half done now. The last two things that need to be taken care of are to correct Debian's default PHP configuration for Apache. You can do this by editing /etc/apache2/mods-available/php5.conf:
Change: AddType application/x-httpd-php .php to: <FilesMatch \.php$> SetHandler application/x-httpd-php </FilesMatch> and save the changes.
And now you'll have to tell Apache to reload its configuration and thus enable PHP:
/etc/init.d/apache2 restart
That's it. You should now be able to run PHP scripts on your newly installed web server.
Stale Cached MimeType
A very frequent question on #apache is, "I've just installed PHP but my browser is offering to download my scripts". This could be because Debian's config puts "application/x-httpd-php php" in its mime.types file, but fortunately the fix is easy. Clear your browser's cache and restart the browser, and then try again.
Resources
DistrosDefaultLayout In order to become familiar with your new Debian-based Apache system you should read this. Also you may be surprised that the Debian folks not only make odd changes to the installation, but fortunately document them well. In /usr/share/doc/apache2/ You should find most of the documentation you need.