PHP 7.3 for Ubuntu and Debian is available from ondrej/php PPA repository. PHP 7.3 stable version has been released with many new features and bug fixes. Always get the latest news from PHP releases news.
Step 1: Add PHP 7.3 PPA
Add ondrej/php which has PHP 7.3 package and other required PHP extensions.
sudo add-apt-repository ppa:ondrej/php
sudo apt update
This PPA can be added to your system manually by copying the lines below and adding them to your system’s software sources.
Step 2: Install PHP 7.3
Once the PPA repository has been added, install php 7.3 on your Ubuntu 18.04 / Ubuntu 16.04 server.
sudo apt install php7.3
Step 3: Installing PHP 7.3 Extensions
Install PHP 7.3 extensions by using the syntax
sudo apt install php7.3-<entension-name>
Step 4: Restart Web server
You may need to restart your Web server after installation of PHP.
# Apache
sudo service apache2 restart
# Nginx
sudo service nginx restart
Enjoy using PHP 7.3 on Ubuntu 18.04 / Ubuntu 16.04 LTS.