Install php 5.6 and composer in ubuntu +18.04 (also WSL2)

install-php5.6-ubuntu.sh

# install php5.6
sudo apt install software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt update
sudo apt install php5.6
php --version

# install required php plugins
sudo apt install php5.6-curl php5.6-xml php5.6-mbstring

# install and setup composer
php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php composer-setup.php
php -r "unlink('composer-setup.php');"
sudo mv composer.phar /usr/local/bin/composer

# install deps
composer install

# run
php artisan key:generate
php artisan serve