[CentOS] how does the bootup screen move the cursor around?

Frank Cox theatre at sasktel.net
Sat Mar 20 05:18:10 UTC 2010

While rebooting my computer after installing the new kernel a few
minutes ago, I got to wondering about how the initial bootup screen
(after grub, before rhgb) is constructed.

The "Loading kernel blah blah blah" lines start at the top of the screen
and proceed to scroll down as one would expect.

But "kernel alive" shows up at the bottom of the screen and then more
write-up is printed above it.

My question is, how does that happen?  Does it write its own esc codes
directly to the screen?  If so, how does it know what terminal we're
using and, therefore, what esc codes to send?

Further into the boot sequence something like ncurses could do the heavy
lifting, but I don't think we're that far along yet.
MELVILLE THEATRE ~ Melville Sask ~ http://www.melvilletheatre.com

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