Only 1 console
edit /etc/inittab
1:2345:respawn:/bin/bash
(this way only work for 1 console, 2 or more consoles not work)
Multi-consoles (reference from KNOPPIX)
edit /etc/inittab
1:12345:respawn:/bin/bash -login >/dev/tty1 2>&1 </dev/tty1
2:2345:respawn:/bin/bash -login >/dev/tty2 2>&1 </dev/tty2
3:2345:respawn:/bin/bash -login >/dev/tty3 2>&1 </dev/tty3
.
.
.