Each console window has an associated "foreground process"; output produced by the foreground process is shown in that console window. Starting a new process while one is already running in the foreground will terminate the existing process.

The %kill built-in can also be used to terminate the currently running foreground process. Clicking the Stop button in the console window has the same effect.

A process can be started in the "background" by adding "&" to the end of its command line. After a process is started in the background, it continues running until it exits. Output is not shown in the console window, and starting other processes has no effect on already-running background processes.

Pressing Control-Z detaches the foreground process. The process continues running in the background, and no longer shows output in the console.