How to activate Serial Console on Debian Squeeze

July 6, 2011,  Christian Kildau,  5 Comments

Activating a Serial Console starting at the bootloader all the way up to a tty login requires just a few steps, but it took me some time to figure out all the knobs. Here’s how to do it with Debian Squeeze:

To have configruation changes persistent in Debian, you may not edit /boot/grub/grub.cfg directly, but need to edit/add the appropiate lines in /etc/defaults/grub:

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GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=ttyS0,9600n8" GRUB_TERMINAL=console GRUB_SERIAL_COMMAND="serial --speed=9600 --unit=0 --word=8 --parity=no --stop=1"

Now run update-grub and you’ll get the Bootloader and all Kernel and Init messages on your serial console the next time you boot.

To get a login promt on serial you need to modify /etc/inittab to:

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1:2345:respawn:/sbin/getty 38400 tty1 2:23:respawn:/sbin/getty 38400 tty2 3:23:respawn:/sbin/getty 38400 tty3 4:23:respawn:/sbin/getty 38400 tty4 5:23:respawn:/sbin/getty 38400 tty5 6:23:respawn:/sbin/getty 38400 tty6 # Serial console s0:2345:respawn:/sbin/getty -L 9600 ttyS0 vt102

That’s it. run init q to reload init and activate serial login, or simply reboot.