3.7.1. beep - play a GRUB beep tune Usage

beep tempo [pitch1 duration1 [pitch2 duration2] ...] Synopsis

Tempo is an unsigned 32bit number. It’s followed by pairs of unsigned 16bit numbers for pitch and duration. The tempo is the base for all note durations. 60 gives a 1-second base, 120 gives a half-second base, etc. Pitches are Hz. Set pitch to 0 to produce a rest. When only tempo is given, a beep of duration 1 at bell frequency results. Options

-c cancel pending beeps
-w wait until beep is over