How to install PHP 5.6 on Lubuntu 17.10

Lubuntu 17.10 artful aardvark comes with php version 7.1 in the repository, but if you want to have the old php 5.6 back, probably because you are working on a project which works well on php 5.6 but not working very well on php 7.1, then installing php 5.6 is make sense.

If you already install php 7.1 on lubuntu, you don't need to uninstall it, the php 5.6 will automatically replace the php 7.1, even more great you can switch back and forth between the two, which i will show later in this tutorial.

How to install PHP 5.6 on Lubuntu 17.10

• open command line/terminal on lubuntu
• add ppa repository ondrej/php

sudo add-apt-repository ppa:ondrej/php

• run update command

sudo apt-get update

• install php 5.6

sudo apt-get install php5.6

• check the php version it should be 5.6

php -v

• done!

You probably need to install some of the most important php modules such as mbstring, curl, gd, mcrypt, xml and so on. If you previously install those on php 7.1 you need to install it again for php 5.6, error message from your php application can show which php module that you need to install.

List of modules for php 5.6

php5.6-bcmath     
php5.6-dba        
php5.6-imap       
php5.6-mcrypt     
php5.6-pspell     
php5.6-sybase
php5.6-bz2        
php5.6-dev        
php5.6-interbase  
php5.6-mysql      
php5.6-readline   
php5.6-tidy
php5.6-cgi        
php5.6-enchant    
php5.6-intl       
php5.6-odbc       
php5.6-recode     
php5.6-xml
php5.6-cli        
php5.6-fpm        
php5.6-json       
php5.6-opcache    
php5.6-snmp       
php5.6-xmlrpc
php5.6-common     
php5.6-gd         
php5.6-ldap       
php5.6-pgsql      
php5.6-soap       
php5.6-xsl
php5.6-curl       
php5.6-gmp        
php5.6-mbstring   
php5.6-phpdbg     
php5.6-sqlite3    
php5.6-zip

How to switch back from php 5.6 to php 7.1
The great thing is you can go back to php 7.1 easily, without uninstalling anything, but first you need to understand that there are two level where php works, first on the web server level and second on the command line level.

web server level

sudo a2dismod php5.6

sudo a2enmod php7.1

sudo service apache2 restart

command line level

sudo update-alternatives --set php /usr/bin/php7.1

sudo update-alternatives --set phar /usr/bin/phar7.1

sudo update-alternatives --set phar.phar /usr/bin/phar.phar7.1