wget https://phar.phpunit.de/phpunit.phar        # download the archive file
chmod +x phpunit.phar                            # make it executable
sudo mv phpunit.phar /usr/local/bin/phpunit      # move it to /usr/local/bin
phpunit --version                                # show installed version number

# If you have composer installed system wide
composer global require phpunit/phpunit  # set PHPUnit as a global dependency
phpunit --version                        # show installed version number

# If you have the .phar file of composer
php composer.phar global require phpunit/phpunit  # set PHPUnit as a global dependency
phpunit --version                                 # show installed version number

# If you have composer installed system wide
composer require phpunit/phpunit  # set PHPUnit as a local dependency
./vendor/bin/phpunit --version    # show installed version number

# If you have the .phar file of composer
php composer.phar require phpunit/phpunit  # set PHPUnit as a local dependency
./vendor/bin/phpunit --version             # show installed version number