grub: sleep

 
 16.3.71 sleep
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  -- Command: sleep [--verbose] [--interruptible] count
      Sleep for COUNT seconds.  If option '--interruptible' is given,
      allow pressing <ESC>, <F4> or holding down <SHIFT> to interrupt
      sleep.  With '--verbose' show countdown of remaining seconds.  Exit
      code is set to 0 if timeout expired and to 1 if timeout was
      interrupted using any of the mentioned keys.