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(grub.info)Serial terminal

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Using GRUB via a serial line
****************************

   This chapter describes how to use the serial terminal support in
GRUB.

   If you have many computers or computers with no display/keyboard, it
would be very useful to control the computers with serial
communications. To connect a computer with another via a serial line,
you need to prepare a null-modem (cross) serial cable, and you may need
to have multiport serial boards, if your computer doesn't have extra
serial ports. In addition, a terminal emulator is also required, such as
minicom. Refer to a manual of your operating system, for more
information.

   As for GRUB, the instruction to set up a serial terminal is quite
simple. First of all, make sure that you haven't specified the option
`--disable-serial' to the configure script when you built your GRUB
images. If you get them in binary form, probably they have serial
terminal support already.

   Then, initialize your serial terminal after GRUB starts up. Here is
an example:

     grub> serial --unit=0 --speed=9600
     grub> terminal serial

   The command `serial' initializes the serial unit 0 with the speed
9600bps. The serial unit 0 is usually called `COM1', so, if you want to
use COM2, you must specify `--unit=1' instead. This command accepts
many other options, so please refer to Note: serial, for more details.

   The command `terminal' (Note: terminal) chooses which type of
terminal you want to use. In that case above, the terminal will be a
serial terminal, but you can also pass `console' to the command, like
`terminal serial console'. In this case, a terminal in which you press
any key will be selected as a GRUB terminal.

   However, note that GRUB assumes that your terminal emulator is
compatible with VT100 by default. This is true for most terminal
emulators nowadays, but you should pass the option `--dumb' to the
command, if your terminal emulator is not VT100-compatible or
implements few VT100 escape sequences. If you specify the option, then
GRUB provides you with an alternative menu interface, because the normal
menu requires several fancy features for your terminal.