How to install php 7.4 on Ubuntu 18.04

Add PHP PPA Repository

apt -y install software-properties-common

add-apt-repository ppa:ondrej/php

Output:

root@vps:~# add-apt-repository ppa:ondrej/php
 Co-installable PHP versions: PHP 5.6, PHP 7.x and most requested extensions are included. Only Supported Versions of PHP (http://php.net/supported-versions.php) for Supported Ubuntu Releases (https://wiki.ubuntu.com/Releases) are provided. Don't ask for end-of-life PHP versions or Ubuntu release, they won't be provided.

Debian oldstable and stable packages are provided as well: https://deb.sury.org/#debian-dpa

You can get more information about the packages at https://deb.sury.org

BUGS&FEATURES: This PPA now has a issue tracker:
https://deb.sury.org/#bug-reporting  

Updating the system

apt-get update

Install PHP 7.4 on Ubuntu

apt -y install php7.4

Output:

root@vps:~# apt -y install php7.4
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  amd64-microcode intel-microcode iucode-tool
Use 'apt autoremove' to remove them.
The following additional packages will be installed:
  apache2 apache2-bin apache2-data apache2-utils libapache2-mod-php7.4 libapr1
  libaprutil1 libaprutil1-dbd-sqlite3 libaprutil1-ldap liblua5.2-0
  libpcre2-8-0 libsodium23 php-common php7.4-cli php7.4-common php7.4-json
  php7.4-opcache php7.4-readline ssl-cert

Once you have installed PHP, check the PHP version.

php -v

Output:

root@vps:~# php -v
PHP 7.4.6 (cli) (built: May 14 2020 10:02:44) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
with Zend OPcache v7.4.6, Copyright (c), by Zend Technologies