To use php to execute an external command, you can use [man]exec[/man] or [man]passthru[/man] or even the backticks operator ( ... ).
You state "without attaching to it on php" ...
What do you mean? Are you asking how to launch the program without using php? If so, it would depend on your operating system. You could use a batch or shell script to launch it or even set the application as a service that runs in the background all of the time on start up.