How Do I Switch Between PHP Versions on Ubuntu?

Introduction

Before we begin talking about how to switch between PHP Versions on Ubuntu, let's briefly understand – What is PHP Version?

Ubuntu provides support for a number of PHP versions for the creation of websites. To fix the flaws in earlier versions, PHP releases frequent upgrades. It's possible that a project made with one version of PHP won't function correctly with another. To get around this, the user has to switch between them in order to use the features of the particular version.

In this tutorial, you will switch between PHP Versions on Ubuntu. We will also address a few FAQs on how to switch between PHP Versions on Ubuntu.

Method 1: Switching Between PHP Versions Using a2 Scripts

You can enable or disable the particular modules using the "a2" apache module. This phenomenon makes it easier to disable a certain PHP version and subsequently enable the one you want. To do this, adhere to the instructions illustrated below:

Step 1: Check the Current PHP version

Let's display the most recent PHP version that the operating system supports. To achieve this, the command is executed as follows:

php -v

The most recent PHP release is 8.1.

Step 2: Disable the PHP Version

The next step is to disable the PHP module for version 8.x using the "a2dismod" command with sudo permission:

sudo a2dismod php8.1

The user must restart the apache2 service in order to activate the new configuration and disable the current PHP version 8.1.

Step 3: Enable the PHP Version

Ensure that your system has the PHP version you want to switch to is installed. We'll enable PHP 5.6 as an example for the system. To enable the PHP, which is version 5.6 in our case, use the "a2enmod" command:

sudo a2enmod php5.6

The PHP 5.6 module is now active.

Step 4: Set the New PHP to Default

Then, use the following command to make the PHP version (5.6 in this case) the default:

sudo update-alternatives --set php /usr/bin/php5.6

The default PHP version is now 5.6.

Step 5: Restart the Apache

To apply the modifications, lastly restart the apache services:

sudo systemctl restart apache2

There has been a restart of the apache service.

Verify the Change

In order to confirm that the previous procedures were successfully carried out, let's check the PHP version:

php -v

PHP has been downgraded to version 5.x.

Method 2: Determine the Symlink of php Command to Switch PHP Versions

The "update-alternatives" command provides the ability to update the default commands' symbolic links. This can be used to alter the php command's default orientation, enabling version switching. Below is a description of the two-step process:

Step 1: List and Change the PHP Version

If your operating system has numerous versions of PHP installed, you can switch between them by using the command below:

sudo update-alternatives --config php

When the following command is run, you will be prompted to enter the selection number of your choosing before pressing the enter key:

Step 2: Verify the Version

Let's check the PHP version and confirm it:

php -v

As specified in the aforementioned selection, PHP version has been changed to 5.6.

FAQs to Switch Between PHP Versions on Ubuntu

Conclusion

Use the "a2dismod" and "a2enmod" commands to enable and disable the various PHP versions, respectively, to switch between them. Set it as the default PHP module after that, and then restart the Apache services. The user can utilize this to downgrade or upgrade to the various PHP versions. Additionally, users can obtain the installed versions and designate one of them as the default by using the "sudo update-alternatives -config php" command. This tutorial has provided instructions on how to change between the various PHP versions on Ubuntu.