Skip to content

Instantly share code, notes, and snippets.

Created September 23, 2014 09:18
Show Gist options
  • Save srijan/383a8d7af6860de6f9de to your computer and use it in GitHub Desktop.
Save srijan/383a8d7af6860de6f9de to your computer and use it in GitHub Desktop.
# Copyright 2008 Nicholas A. Schembri State College PA USA
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see
# <>.
# Thank you Voyage Linux for the idea, Great job on release 0.5
# Tested with 8.04.1
# tested with 9.10
# tested with debian live 6.0.1
# ****************************************************************************************
# Change log
# 2008.08.01 Added debugging comments in "drop to a shell" section. grub option aufs=tmpfs-debug will stop the init script.
# reviewed *********** fix fstab on tmpfs ******************
# rootaufs failed when system was booted with /dev/xxx and fstab had uuid= info.
# BlaYO pointed out the best and simplest solution was to use grep -v. Grep replaces a sed one liner.
# Add the comment block to fstab
# 2009.12.07 Corrected issue caused by Apparmor.
# Name changed to __rootaufs.
# 2011.08.19 Changed if condition to avoid issue (sh: bad number) when $aufsdebug is not set.
# Now checks exists apparmor before delete.
# 2011.08.20 For work correctly with Debian Live 6.0.1 ( two lines must be removed from rc.local modification part:
# 'mount -f /ro'
# 'echo aufs-tmpfs /rw tmpfs rw 0 0 >>/etc/mtab'
case $1 in
exit 0
export aufs
for x in $(cat /proc/cmdline); do
case $x in
case $aufs in
if [ "$aufs" != "tmpfs" ]; then
#not set in boot loader
#I'm not loved. good bye
exit 0
# This is a simple overview of the steps needed to use aufs on the root file system and see the /rw and /ro branches.
# initramfs init-botton script
# move the root file system to aufs/unionfs readonly /ro
# root is mounted on ${rootmnt}
# create tmpfs on /rw
# create a aufs using /ro and /rw
# put some files on the tmpfs to fix mtab and fstab
# move aufs to rootmnt to finish the init process.
# No changes to the root file system are made by this script.
# Why!
# This will allow you to use a usb flash drive and control what is written to the drive.
# no need to rebuild the squashfs file just to add a program.
# boot to single user mode. The system works the way you expect. boot aufs=tmpfs and no changes are written to the flash.
# run ubuntu on an eeePC .
# Install
# Install ubuntu 8.04 Hardy. Hardy has aufs installed by default
# apt-get update
# apt-get dist-upgrade
# apt-get install aufs-tools
# echo aufs >> /etc/initramfs-tools/modules
# put this file in /etc/initramfs-tools/scripts/init-bottom/rootaufs
# chmod 0755 rootaufs
# # clean up menu.lst
# update-grub
# update-initramfs -u
# vi /boot/grub/menu.lst
# add aufs=tmpfs to the default entry.
# do not add this line to single user mode.
# boot to single user mode in order to install software.
# note: if your home account is on the root file system, your files are in ram and not saved.
echo " root-aufs: Setting up aufs on ${rootmnt} as root file system "
modprobe -q -b aufs
if [ $? -ne 0 ]; then
echo root-aufs error: Failed to load aufs.ko
exit 0
#make the mount points on the init root file system
mkdir /aufs
mkdir /rw
mkdir /ro
# mount the temp file system and move real root out of the way
mount -t tmpfs aufs-tmpfs /rw
mount --move ${rootmnt} /ro
if [ $? -ne 0 ]; then
echo root-aufs error: ${rootmnt} failed to move to /ro
exit 0
mount -t aufs -o dirs=/rw:/ro=ro aufs /aufs
if [ $? -ne 0 ]; then
echo root-aufs error: Failed to mount /aufs files system
exit 0
#test for mount points on aufs file system
[ -d /aufs/ro ] || mkdir /aufs/ro
[ -d /aufs/rw ] || mkdir /aufs/rw
# the real root file system is hidden on /ro of the init file system. move it to /ro
mount --move /ro /aufs/ro
if [ $? -ne 0 ]; then
echo root-aufs error: Failed to move /ro /aufs/ro
exit 0
# tmpfs file system is hidden on /rw
mount --move /rw /aufs/rw
if [ $? -ne 0 ]; then
echo root-aufs error: Failed to move /rw /aufs/rw
exit 0
#*********** fix fstab on tmpfs ******************
# test for /dev/sdx
# this is not on the real file system. This is created on the tmpfs each time the system boots.
# The init process will try to mount the root filesystem listed in fstab. / and swap must be removed.
# the root file system must be mounted on /ro not on /
if [ "0$aufsdebug" -eq 1 ]; then
echo " root-aufs debug: Remove the root file system and swap from fstab "
echo " resume $resume "
echo ' BlaYO pointed out that grep can be used to quickly remove '
echo ' the root file system from fstab. '
echo ' Thank you BlaYO for the debug info.'
# old code
# I'm sure that sed can do this in one step but I want to correct on the rootname not matching the root in fstab.
#cat /aufs/ro/etc/fstab|sed -e s/$ROOTNAME/\#$ROOTNAME/ -e s/$resume/\#$resume/ >/aufs/etc/fstab
#Add the comment block to fstab
cat <<EOF >/aufs/etc/fstab
# RootAufs has mounted the root file system in ram
# This fstab is in ram and the real fstab can be found /ro/etc/fstab
# the root file system ' / ' has been removed.
# All Swap files have been removed.
#remove root and swap from fstab
cat /aufs/ro/etc/fstab|grep -v ' / ' | grep -v swap >>/aufs/etc/fstab
if [ $? -ne 0 ]; then
echo root-aufs error: Failed to create /aufs/etc/fstab
#exit 0
# add the read only file system to fstab
#ROOTTYPE=$(/lib/udev/vol_id -t ${ROOT})
ROOTTYPE=$(cat /proc/mounts|grep ${ROOT}|cut -d' ' -f3)
ROOTOPTIONS=$(cat /proc/mounts|grep ${ROOT}|cut -d' ' -f4)
echo ${ROOT} /ro $ROOTTYPE $ROOTOPTIONS 0 0 >>/aufs/etc/fstab
# S22mount on debian systems is not mounting /ro correctly after boot
# add to rc.local to correct what you see from df
#replace last case of exit with #exit
cat /aufs/ro/etc/rc.local|sed 's/\(.*\)exit/\1\#exit/' >/aufs/etc/rc.local
echo mount -f /ro >>/aufs/etc/rc.local
# add back the root file system. mtab seems to be created by one of the init proceses.
echo "echo aufs / aufs rw,xino=/rw/.aufs.xino,br:/rw=rw:/ro=ro 0 0 >>/etc/mtab" >>/aufs/etc/rc.local
echo "echo aufs-tmpfs /rw tmpfs rw 0 0 >>/etc/mtab" >>/aufs/etc/rc.local
echo exit 0 >>/aufs/etc/rc.local
# Copyright 2008 Joaquín I. Bogado García
#fix para apparmor, se desactiva y listo ( From the lethe project. )
[ -e /scripts/init-bottom/_apparmor ] && rm /scripts/init-bottom/_apparmor
[ -e /aufs/etc/init.d/apparmor ] && rm /aufs/etc/init.d/apparmor
#build remountrw
echo \#!/bin/sh >/aufs/bin/remountrw
echo mount -o remount,rw ${ROOT} >>/aufs/bin/remountrw
chmod 0700 /aufs/bin/remountrw
#build remountro
echo \#!/bin/sh >/aufs/bin/remountro
echo mount -o remount,ro ${ROOT} >>/aufs/bin/remountro
chmod 0700 /aufs/bin/remountro
# This should drop to a shell. (rewrite)
if [ "0$aufsdebug" -eq 1 ]; then
echo " root-aufs debug: mount --move /aufs ${rootmnt} "
echo ' root-aufs debug: init will stop here. '
exit 0
mount --move /aufs ${rootmnt}
exit 0
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment