grub: Menu interface
14.2 The simple menu interface
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The menu interface is quite easy to use. Its commands are both
reasonably intuitive and described on screen.
Basically, the menu interface provides a list of "boot entries" to
the user to choose from. Use the arrow keys to select the entry of
choice, then press <RET> to run it. An optional timeout is available to
boot the default entry (the first one if not set), which is aborted by
pressing any key.
Commands are available to enter a bare command-line by pressing <c>
(which operates exactly like the non-config-file version of GRUB, but
allows one to return to the menu if desired by pressing <ESC>) or to
edit any of the "boot entries" by pressing <e>.
If you protect the menu interface with a password (⇒Security),
all you can do is choose an entry by pressing <RET>, or press <p> to
enter the password.