cdist/hacking/v3-busybox/init

#!/bin/sh

#Create all the symlinks to /bin/busybox
/bin/busybox --install -s

#Mount things needed by this script
mount -t proc proc /proc
mount -t sysfs sysfs /sys

#Disable kernel messages from popping onto the screen
echo 0 > /proc/sys/kernel/printk


#Create device nodes
mknod /dev/null c 1 3
mknod /dev/tty c 5 0
mdev -s

#Function for parsing command line options with "=" in them
# get_opt("init=/sbin/init") will return "/sbin/init"
get_opt() {
    echo "$@" | cut -d "=" -f 2
}

#Defaults
init="/sbin/init"
root="/dev/hda1"

#Process command line options
for i in $(cat /proc/cmdline); do
    case $i in
        root\=*)
            root=$(get_opt $i)
            ;;
        init\=*)
            init=$(get_opt $i)
            ;;
    esac
done


exec sh

# Skipping the rest

#Mount the root device
mount "${root}" /newroot

#Check if $init exists and is executable
if [[ -x "/newroot/${init}" ]] ; then
    #Unmount all other mounts so that the ram used by
    #the initramfs can be cleared after switch_root
    umount /sys /proc
    
    #Switch to the new root and execute init
    exec switch_root /newroot "${init}"
fi

#This will only be run if the exec above failed
echo "Failed to switch_root, dropping to a shell"
exec sh