PHP Command Line Interface (CLI).
# To parse and execute a php script:
php file
# To check syntax on (i.e. lint) a PHP script:
php -l file
# To run PHP interactively:
php -a
# To run PHP code (Notes: Don't use <? ?> tags; escape double quotes with backslash):
php -r "code"
# To start a PHP built-in web server in the current directory:
php -S host:port