PHP-GD installed but not activated in RedHat 5.5 Enterprise

When I do the same grep of my config files, I get one line you didn't:

/etc/apache2/mods-enabled/dir.conf:3:          DirectoryIndex index.html index.cgi index.pl index.php index.xhtml index.htm

Make sure this line in /etc/php5/apache2/php.ini is set this way:

; Enable the PHP scripting language engine under Apache.
engine = On

If you change it, restart Apache:

sudo apache2ctl restart

You can compile and install manually only the mcrypt extension. This is what I did in my CentOS 5.6 VPS:

First install some required packages:

yum install php53-devel libmcrypt-devel gcc gcc-c++

Then download the php 5.3.6 source code from php.net and unpack it:

wget http://mx2.php.net/get/php-5.3.6.tar.bz2/from/us3.php.net/mirror
tar xvjf php-5.3.6.tar.bz2

(Please note that the download link will change with every subsequent PHP release.)

Go to the directory with the mcrypt extension source code and compile:

cd php-5.3.6/ext/mcrypt/
phpize
aclocal
./configure
make

Then install:

make install

Create the configuration file for PHP /etc/php.d/mcrypt.ini containing:

extension=mcrypt.so

Restart apache:

/etc/init.d/httpd restart

Create a file with phpinfo just to check if the extension was loaded:

<?php
phpinfo();
?>