NewRelic is an Application performance monitoring tool. To install it on CentOS LAMP server (PHP), run

cd /usr/local/src
wget http://download.newrelic.com/php_agent/release/newrelic-php5-4.15.0.74-linux.tar.gz
tar zxvf newrelic-php5-4.15.0.74-linux.tar.gz
cd newrelic-php5-4.15.0.74-linux
./newrelic-install install

You need need a NewRelic.com account before you can start monitoring your Application.

[root@cloud1 newrelic-php5-4.15.0.74-linux]# ./newrelic-install install

New Relic PHP Agent Installation (interactive mode)
===================================================


In order for the New Relic agent to function correctly it requires a license
key. Please enter that key now. If you do not have your license key handy you
can add it to your INI file(s) later. Please be aware that the license key you
specify here will be installed in the default INI files, and will be the key
used for any virtual host or directory / application that does not override
the key on a per-host or per-directory basis. This is only relevant if you run
a multi-tenant site. Please contact http://support.newrelic.com
if you run such a site and have any questions.

If you are upgrading from a previous version please leave this blank. Please
also note that the key you enter here will not replace any existing key in
your INI file(s). It applies only to newly created INI files or INI files that
have not been modified by this script before.

   Enter New Relic license key (or leave blank): MY_SECRET_KEY_HERE
Found a valid PHP in : /usr/bin
         PHP Version : 5.4.16
  Module API version : 20100525
    Module directory : /usr/lib64/php/modules
  Zend Thread Safety : no
   CLI ini directory : /etc/php.d
      Install Status : /etc/php.d/newrelic.ini created
      Install Status : OK

The agents need the New Relic proxy daemon to be installed and running. Without
this daemon no data will be transmitted to the New Relic web site. It is highly
recommended that you allow this script to install the daemon into the default
location, which is:

    /usr/bin/newrelic-daemon

If you do not have permission to install the daemon to this directory (you
need to be root to have permission) then please select no at the prompt
below. Also please note that as of version 3.0 of the New Relic PHP agent
this daemon does not need to be started automatically by the system. The
daemon is configured from, and started by, the agent. Please refer to the
New Relic for PHP documentation for details.

   Install daemon ([y]es, [n]o or x to e[x]it): y

New Relic is now installed on your system. Congratulations!

The last step before you will start seeing data in your account is to restart
your web server or servers, or whatever environment hosts the PHP you wish to
monitor. For example, you may need to restart Apache or nginx, or if you are
using php-fpm and FastCGI, you will need to restart php-fpm. If you installed
New Relic into multiple locations you may have multiple PHP hosts to restart.
If everything is working properly you should see the following two log files:

    /var/log/newrelic/newrelic-daemon.log
    /var/log/newrelic/php_agent.log

Now you should create a simple test php script that contains the line:

   <?php phpinfo(); ?>

and point your browser at the test script, and you should see the New Relic
extension and its settings. If you still do not see those log files or data in
your account please contact our support staff at http://support.newrelic.com
and be sure to include the following file in your bug report:

    /tmp/nrinstall-20141126-034838-4329.tar

Thank you for choosing New Relic!
[root@cloud1 newrelic-php5-4.15.0.74-linux]#