beep, flash - curses bell and screen flash routines
The beep and flash routines are used to alert the terminal user. The
routine beep sounds an audible alarm on the terminal, if possible; oth‐
erwise it flashes the screen (visible bell). The routine flash flashes
the screen, and if that is not possible, sounds the alert. If neither
alert is possible, nothing happens. Nearly all terminals have an audi‐
ble alert (bell or beep), but only some can flash the screen.
These routines return OK if they succeed in beeping or flashing, ERR
SVr4's beep and flash routines always returned OK, so it was not possi‐
ble to tell when the beep or flash failed.
These functions are defined in the XSI Curses standard, Issue 4. Like
SVr4, it specifies that they always return OK.