Detecting serial console in a shell script

[Alastair M. <mck...@co...>]

Hello Console experts!

I am looking for a good technique for detecting whether /dev/console is
a serial console; one that works on current 2.2/2.4 kernels and will
remain working in the new framework.

Currently there is a bug against using
tty | grep ttyS=20
as unreliable, as at this point during boot in user space, we're running
on /dev/console whether screen or console is in use.

Can anyone name a better solution? one solution is to write a program
to use ioctl(TIOCGSERIAL) (setserial can't be guaranteed to be there).

Thanks,
Alastair McKinstry
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