keyp
KEYP
KEY?
predicate, outputs TRUE if there are characters waiting to be
read from the read stream. If the read stream is a file, this
is equivalent to NOT EOFP. If the read stream is the terminal,
then echoing is turned off and the terminal is set to CBREAK
(character at a time instead of line at a time) mode. It
remains in this mode until some line-mode reading is requested
(e.g., READLIST). The Unix operating system forgets about any
pending characters when it switches modes, so the first KEYP
invocation will always output FALSE.