Installing PHP APC on GNU/Linux Centos 5

Complex PHP applications, such as Drupal, can gain a lot of performance benefits from running a PHP op-code cache/accelerators.

APC,
Alternate PHP Cache, is now the most maintained free/open source op-code cache, and is being used more and more as it emerges to be the
most stable.

The instructions here detail how to get APC running on a CentOS 5 server. The server happened to have Plesk on it as well, which initially made me hesitant to install APC "normally", since Plesk is so picky on what other software is installed on the server. However, it seems to have worked out well.

First, we need the pecl command so we can download and install APC from the repositories.

Do to so, we execute the following command:

yum install php-pear

But, this will not run on its own, we need the following package for the phpize command:

yum install php-devel

We also need the apxs command, which is installed via the following package:

yum install httpd-devel

Now we have all the software we need, so we install apc via the pecl command:

pecl install apc 

Once that finishes, we need to enable apc in Apache's configuration. the following command should do this for us.

echo "extension=apc.so" > /etc/php.d/apc.ini

Then we restart Apache:

/etc/init.d/httpd start

And we are all done. Watch for less execution time per page, and decreased memory usage per Apache process compared to what you had
before.