Expect script to select options in GRUB menu

Question

Is it possible to select options in GRUB menu to select appropriate option to boot the device ?

I have a serial connection to the device and I am writing the expect script to send the DOWNARROW key to select the appropriate option in the GRUB menu at bootup. But for some reason it doesn't work out.

expect "GRUB loading."
#down arrow
send {^[\[B}

send "\r"
send "\r"

`^[\[B` is probably not what you want to send. Try `send \x1F` — Johannes Kuhn, Mar 03 '16 at 04:33
Atleast in Linux it is ^[\[B for down arrow. I even tried with \x1F and still i am facing the same issue — codingfreak, Mar 03 '16 at 05:02
Can you somehow see what bytes would be sent if you press the down key? — Johannes Kuhn, Mar 03 '16 at 05:10

score 1 · Answer 1 · answered Jun 21 '17 at 19:46

After trying multiple methods of issuing a 'down arrow' with expect, I managed to get this to work using grub2:

send \003N

This sends Ctl+N, which works as a secondary down arrow, seen and explained better here: https://unix.stackexchange.com/questions/137323/grub2-without-arrow-keys

score 0 · Answer 2 · answered Mar 03 '16 at 14:09

0

Since you are using braces, you don't need to escape the [

send -- {^[[B}  ;# where "^[" is entered with ctrl-V Esc

Or using double quotes, where the open bracket does need to be escaped, but it's easier to type the escape character.

send -- "\033\[B"

answered Mar 03 '16 at 14:09

glenn jackman

238,783
38
220
352

Even tried the above options ... and seems it is not working. Somehow in grub menu it is not selecting the second option – codingfreak Mar 04 '16 at 14:37
Try using `autoexpect` to record a manual session and see what gets produced. – glenn jackman Mar 04 '16 at 14:53
I tried autoexpect ... where it is using "send {^[\[B}" only – codingfreak Mar 09 '16 at 01:51

score 0 · Answer 3 · edited Dec 15 '22 at 06:50

0

send "\033\[B"

works for moving down the menu in grub (\033 is the ESC char)

so then for example

send "\033\[B\033\[B\r"

will move you down twice and then send a carriage return-- choose third option in menu

edited Dec 15 '22 at 06:50

logi-kal

7,107
6
31
43

answered Dec 08 '22 at 13:34

Marta Lewandowska

1

Expect script to select options in GRUB menu

3 Answers3