Php

install composer

php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php -r "if (hash_file('sha384', 'composer-setup.php') === '55ce33d7678c5a611085589f1f3ddf8b3c52d662cd01d4ba75c0ee0459970c2200a51f492d557530c71c15d8dba01eae') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
php composer-setup.php
php -r "unlink('composer-setup.php');"

sudo mv composer.phar /usr/local/bin/composer

Install

sudo apt-get install php -y
sudo apt-get install -y php-{bcmath,bz2,intl,gd,mbstring,mysql,zip} && sudo apt-get install libapache2-mod-php  -y

install 7.4 on mac

From: https://getgrav.org/blog/macos-catalina-apache-multiple-php-versions

From: https://gist.github.com/dtomasi/ab76d14338db82ec24a1fc137caff75b

 brew tap exolnet/homebrew-deprecated
 brew install php@7.4
 LoadModule php7_module /usr/local/opt/php@7.3/lib/httpd/modules/libphp7.so

 brew services start php@7.4
 lsof -Pni4 | grep LISTEN | grep php

 brew unlink php
 brew link php@7.4

install php 8 on ubuntu

With root access:

apt update && apt install -y wget gnupg2 lsb-release
wget https://packages.sury.org/php/apt.gpg && apt-key add apt.gpg
echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" | tee /etc/apt/sources.list.d/php.list
apt update && apt install -y php8.1
php -v # Outputs "PHP 8.1.3 ..."

Libraries

Composer

sudo apt install composer
composer install

phpunit

Update:

wget https://phar.phpunit.de/phpunit.phar
chmod +x phpunit.phar
which phpunit
sudo mv phpunit.phar /usr/local/bin/phpunit

Troubleshoot

Turn on logging

@ini_set( 'display_errors', getenv('display_errors') );
@ini_set( 'display_errors', 1 );

/var/www/html/wp-content/debug.log will have the file.