Upgrading To PHP 5.5

PHP 5.5 introduces several new features without (hopefully) deprecating any features you probably use, so upgrading should be a relatively painless procedure. Before we look at the exact steps to upgrade on Ubuntu Linux, let’s look at some of the new features in PHP 5.5.

What’s New In PHP 5.5

For a complete list of significant changes, check the PHP NEWS file in your release. Here’s what I think you’ll care about the most:

  • New functions which simplify password hashing. Lazy programmers who have missed out on the security benefits of password hashing no longer have any excuse to use plain text passwords. Here’s a simple example from the PHP documentation which illustrates how simple the new API is to use:
echo password_hash("rasmuslerdorf", PASSWORD_DEFAULT)."\n";

if (password_verify('rasmuslerdorf', $hash)) {
    echo 'Password is valid!';
} else {
    echo 'Invalid password.';
  • You can now use list() in foreach() to save a little bit of typing and, more importantly, simplify your code. Here’s an example from the PHP Wiki of how you can now write a simple loop:
$users = array(
    array('Foo', 'Bar'),
    array('Baz', 'Qux'),

foreach ($users as list($firstName, $lastName)) {
    echo "First name: $firstName, last name: $lastName. ";
  • empty() can now accept non-variable arguments, which can make your code more readable when you want to test a function which returns an array or other data.

Getting PHP 5.5 For Ubuntu

As I write this in July 2013, PHP 5.5 is not yet available for Ubuntu from an Ubuntu repository. I also can’t find a Personal Package Archive (PPA) which contains 5.5 and its dependencies, so the only way to get it for now is to build it yourself.

Building your own packages for a production server is a bad idea unless you have a paid team prepared to rebuild PHP every time a security update comes out. But compiling PHP 5.5 for a test box (or virtual machine) so you can prepare your code now for a later update is a good idea.

Note: if you’re installing on a new computer or virtual machine just for PHP 5.5, you may want to try Debian Unstable (Sid) or another Linux distribution which already includes PHP 5.5.

You want to start out by installing all of the packages you need to run your project, such as a webserver and database. You know what you need and you probably already have an install script, so I won’t tell you what to do.

Next you need a C compiler and some other core software building tools—the good old GNU toolchain. To get them on Ubuntu, simply type:

sudo apt-get install build-essential

PHP depends on various system software; you can install most of these dependencies automatically by running the following command which will install the build dependencies for the version of PHP 5 on your current version of Ubuntu (which will probably be PHP 5.3 or PHP 5.4):

sudo apt-get build-dep php5

Now you need to download the PHP 5.5 archive from PHP.net and untar it. PHP has lots of configuration options you can set—the options you will care about the most are what database backends to use. To see all of the available options, change directory (cd) into the PHP source code directory you untarred and run the following command:

./configure --help

Choose your options and then run configure:

./configure [your options]

Configure will tell you if you have any missing dependencies. If you use a recent version of Ubuntu and ran the build-dep command mentioned earlier, you should be ok. After configure completes successfully, build PHP 5.5 (which will take a few minutes) and install it:

sudo make install

If you discover you forgot an important option to configure—for example, you didn’t include the right DBI—simply re-run configure, make, and sudo make install.

Again, I recommend against using a home-built PHP on a production server, but using it on your workstation or test box will be just fine. (And, hopefully, Ubuntu will give us an official PHP 5.5 package to play with soon.)