How to install and configure APC Cache on a RedHat/CentOS server?

APC cache is a PHP caching solution which stands for Alternative PHP Cache. It serves PHP pages from a cache thus helping to reduce server load. APC is an open source software and is updated from time to time.
The following are the steps to install APC cache on a CentOS server OR even on a cPanel and Plesk server. All these commands are executed via SSH as a ‘root’ user.
1) Firstly, goto a temporary directory

# cd /usr/local/src

2) Download the latest APC version

# wget http://pecl.php.net/get/APC-3.1.6.tgz

3) Unpack the version and change to the APC directory

# tar -zxf APC-3.1.6.tgz
# cd APC-*

4) Create configuration files

# phpize

5) Search for the “php-config” file since you need to configure APC with it

# which php-config

6) Now, configure APC

./configure --enable-apc --enable-apc-mmap --with-apxs \
--with-php-config=/usr/local/bin/php-config

7) Create the installation files and install APC

# make
# make install

Now that the APC cache is installed on your server, the final step is to activate the APC extension in the php.ini file. Locate the working php.ini file and edit it

# php -i | grep php.ini

Search for “extension_dir” and place the following code under it:

extension="apc.so"
apc.enabled=1
apc.shm_segments=1
apc.shm_size=256
apc.ttl=3600
apc.user_ttl=7200
apc.num_files_hint=1024
apc.mmap_file_mask=/tmp/apc.XXx
apc.enable_cli=1

Save the file and restart the Apache web server. You can tweak the APC settings by editing the above file but make sure you restart the Apache service for the new changes to take affect.
That’s it. To check if APC is activated, execute

# php -i | grep apc

Note: once APC is installed, make sure the ‘apc.so’ file is created under the directory specified at the “extension_dir” in php.ini. If not, look for the exact path of the file and create a symlink under it.