Enter cbreak mode.
flag
If false, the effect is the same as calling nocbreak().
In cbreak mode (sometimes called "rare" mode) normal tty line buffering
is turned off and characters are available to be read one by one.
However, unlike raw mode, special characters (interrupt, quit, suspend,
and flow control) retain their effects on the tty driver and calling
program. Calling first raw() then cbreak() leaves the terminal in
cbreak mode.