Switching PHP versions on Ubuntu
Different tasks may require running multiple versions of PHP.
You may need to switch PHP versions by running two sites on the same server or testing older versions of code using outdated methods.
We can switch PHP versions on Ubuntu using the command line with just a few commands.
This article explains the complete process of switching PHP versions on Ubuntu.
How to switch PHP versions on Ubuntu
First, let's check the version of PHP installed on our system. Open Ubuntu bash and insert the following command:
$ php -v
The output will show the version of PHP used on our system.
Output:
PHP 7.4.3 (cli) (built: Nov 25 2021 23:16:22) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
with Zend OPcache v7.4.3, Copyright (c), by Zend Technologies
The output shows that only PHP 7.4.3 is installed on our system. Install another version of PHP first and then try to switch.
Insert the following command to install PHP 5.6:
#add php repository; this repository might not install earlier or later versions of PHP.
$ sudo add-apt-repository -y ppa:ondrej/php
#update sudo
$ sudo apt update
#install php 5.6
$ sudo apt install php5.6
The output of each command should not retrieve errors. Otherwise, PHP 5.6 will not be installed.
If you check the PHP version again, the output is still the same.
To switch PHP version from 7.4.3 to 5.6, insert the following command in bash.
To disable PHP 7.4.3:
$ sudo a2dismod php7.4
Output:
Module php7.4 already disabled
If the output is different than above, you may need to install apache mod and run the above command to disable PHP 7.4. Run this command to install apache mod.
$ sudo apt-get install libapache2-mod-php7.4
After disabling PHP 7.4, run the following command to enable PHP 5.6:
$ sudo a2enmod php5.6
Output:
Considering dependency mpm_prefork for php5.6:
Considering conflict mpm_event for mpm_prefork:
Considering conflict mpm_worker for mpm_prefork:
Module mpm_prefork already enabled
Considering conflict php5 for php5.6:
Module php5.6 already enabled
You may need to restart apache between running these commands.
$ sudo service apache2 restart
PHP switches from 7.4 to 5.6. If you need to set PHP 5.6 as the default version, use the following command.
#This command will directly set PHP 5.6 as default. Manual Switching
$ sudo update-alternatives --set php /usr/bin/php5.6
#This command will give you the option to select a default PHP version. Interactive Switching
$ sudo update-alternatives --config php
Output:
There are 3 choices for the alternative php (providing /usr/bin/php).
Selection Path Priority Status
------------------------------------------------------------
0 /usr/bin/php7.4 74 auto mode
* 1 /usr/bin/php5.6 56 manual mode
2 /usr/bin/php7.0 70 manual mode
3 /usr/bin/php7.4 74 manual mode
Press <enter> to keep the current choice[*], or type selection number:
You can select any version by simply entering the corresponding number. The selected version will be set as default.
You may also need to set other PHP extensions as default. For example:
$ sudo update-alternatives --config phar
The command will also give you phara list of versions and you can choose the default as above. It will help if you restart apache after you are done setting the defaults.
$ sudo service apache2 restart
To switch back to PHP 7.4, you have to run these commands in reverse.
$ sudo a2dismod php5.6
$ sudo a2enmod php7.4
$ sudo service apache2 restart
The output will show that PHP 5.6 is disabled and 7.4 is enabled. Restart apache if needed.
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