tcp_watch_user(-Old, +On_or_Off)

Not available under Windows.

This causes tcp_select/[1,2] (see ipc-tcp-trm-select1) to return the atom user_input whenever input is available on stdin.

Unless stdin is unbuffered, the atom user_input will only be returned after a newline is received.

tcp_watch_user/2 raises a domain error if either of its arguments do not unify with either of the atoms on or off.