(So you can paste/write code in the console.)
To make it parse a file and output to the console:
php -f file.php
Parse a file and output to another file:
php -f file.php > results.html
Do you need something else?
To run only a small part, one line or like, you can use:
php -r '$x = "Hello World"; echo "$x\n";'
If you are running Linux then do
man php at the console.
If you need/want to run PHP through fpm (FastCGI Process Manager), use cli fcgi:
SCRIPT_NAME="file.php" SCRIP_FILENAME="file.php" REQUEST_METHOD="GET" cgi-fcgi -bind -connect "/var/run/php-fpm/php-fpm.sock"
Where /var/run/php-fpm/php-fpm.sock is your php-fpm socket file.