minimal getty but bash script

getty.sh

#!/bin/sh
# minimal getty like script
# speed ignored. 
# bgetty 38400 tty1 /bin/login
if [ $# -lt 3 ] ; then
    echo "Usage: $0 [speed] [tty] [command]"
    exit 1
fi
exec >/dev/$2
exec </dev/$2
exec 2>/dev/$2
shift 2
while true ; do
    busybox setsid "$@"
done