openwrt/target/linux/x86/base-files/lib/preinit/89_move_config

#!/bin/sh
# Copyright (C) 2012 OpenWrt.org

move_config() {
	local rootfsdev
	local rootfstype
	
	rootfstype="$(awk 'BEGIN { RS=" "; FS="="; } ($1 == "rootfstype") { print $2 }' < /proc/cmdline)"
	case "$rootfstype" in
		squashfs|jffs2)
			rootfsdev="$(awk 'BEGIN { RS=" "; FS="="; } ($1 == "block2mtd.block2mtd") { print substr($2,1,index($2, ",")-1) }' < /proc/cmdline)";;
		ext4)
			rootfsdev="$(awk 'BEGIN { RS=" "; FS="="; } ($1 == "root") { print $2 }' < /proc/cmdline)";;
	esac

	mount -t ext4 -o rw,noatime "${rootfsdev%[0-9]}1" /mnt
	mv -f /mnt/sysupgrade.tgz /
	umount /mnt
}

boot_hook_add preinit_main move_config