How to chroot Ubuntu using Live CD

to fix GRUB rescue prompt
by Black God june 2010
(adapted with my example)
Recently I messed up GRUB boot loader in my laptop installed with Ubuntu which resulted in grub rescue prompt. So I had to boot Ubuntu Live CD to get it fixed. Thought of blogging it, may be useful for some one.
This fix involves two steps. First one is to chroot into Ubuntu installation partition. Second one is to install the grub MBR (Master Boot Record). I am using Ubuntu Lucid 10.04 and Live CD also of same.
Step-1: Boot your machine with Ubuntu Live CD and select  
Trying Ubuntu without installation option when it is prompted (Live CD mode)
Step-2: Be patient till you get complete desktop ready.
Step-3: Ubuntu main menu - Places - Home Folder
Look for other partitions listed on left hand side pane.
Mount one by one and identify your Ubuntu root partition. When you are in your root partition, press Ctrl+L to view the complete mount path. Press Ctrl+C to copy this path. This path is normally /media/xx..xx kind of long path, where xx..xx denotes your hard disk partition unique id.

If you know your Ubuntu root partition you can replace the above GUI step-3 with simple mount command like this (Applications - Accessories - Terminal) [or Ctrl + Alt + T]:
$ sudo mount /dev/sda7 /mnt/myroot 
sudo mount /dev/sda2 /mnt/myroot/boot
sudo mount /dev/sda8 /mnt/myroot/home

[where sda7 is your root partition (and if separated)
sda2 your boot partition and sda8 your home partition]

Forget the special case above (Not mounted partitions at myroot) and let’s say you have mounted root partition at /media/xx..xx.
Step-4: Run the terminal through Applications - Accessories - Terminal.
Step-5: Run the following commands to export the pseudo file system of Live CD to your would be root file system soon.

$ sudo mount ‐‐bind /dev /media/xx..xx/dev
$ sudo mount ‐‐bind /proc /media/xx..xx/proc
$ sudo mount ‐‐bind /sys /media/xx..xx/sys

Step-6: Changing the root file system of live system to your hard disk installed root file system.

$ sudo chroot /media/xx..xx

Step-7: Installing GRUB Boot record in Master Boot record of your hard disk. My hard disk is sda. Replace your hard disk device node in the following command.

$ sudo grub-install /dev/sda

Step-8: Reboot the Live Ubuntu. Eject the CD.
Now you should get boot menu for your Ubuntu installation back. Enjoy the Ubuntu!
Note: How to get it done without Live CD which includes GRUB2 rescue prompt
Related content:
How to fix GRUB rescue prompt without Live CD? (For GRUB2)
How to safely remove ubuntu in dual boot installation
Ubuntu 6.06 installation on Legacy PC (low RAM)
HOWTO: /dev file system in chroot-ed environment
Boot CDROM through GRUB
==========================11.04 - How to chroot Ubuntu
What is the recommended way to use chroot from Ubuntu 11.04 with Ubuntu 11.10?
Linked (but probably separate) is "Is there anything special that I need to do in order to get Xorg working?"
Reason I ask is because I'd like to test a few GTK3 programs without losing my current (stable) Ubuntu, or having to get my data synced.
Answer

Could you please tell us why exactly you are doing this? 

You can chroot, but all that will do is change your root to 11.10. init/kernel/kernel modules will still have run from 11.04, so you won't really be running 11.10. This could be useful if you're trying to install grub or something from 11.10, but otherwise it's just silly.

/span>
In order to chroot to do things like.. configure/install grub, do the following-

#first, mount new install to /mnt/oneiric
mount -t proc proc /mnt/oneiric/proc
mount -t sysfs sys /mnt/oneiric/sys
mount -o bind /dev /mnt/oneiric/dev
chroot /mnt/oneiric /bin/bash

I wouldn't try to start full gnome this way.
The only reason you should really be doing this is if you can't boot into the linux installation for some reason, but still need to run a few things from it. You can't just chroot over and change the distro you're running. 

========================

Source
Question
I'm setting up a large software RAID array using MDADM, and don't want to waste a drive bay on a system disk. Unfortunately, the server I'm working with has trouble booting from a USB drive, so I'm attempting a workaround.

I want to create a LiveCD with Knoppix or some other suitable distribution, then use the USB drive as a mountable storage device to keep all my admin scripts etc on. I plan on running several services including:

Samba SSH SFTP Subversion (SVNServe)

I'm used to running a headless Fedora server, and that would be ideal, but I'll take what I can get. Can anyone suggest a good approach for this problem? Specifically - an appropriate distribution to use, how to configure the LiveCD, and how to get it to automatically mount and run certain scripts on the USB drive?

Answer 

Use grml, a bootable live system (Live-CD) based on Debian. Grml includes a collection of GNU/Linux software especially for system administrators and users of texttools. Grml provides automatic hardware detection. You can use Grml (for example) as a rescue system, for analyzing systems/networks or as a working environment. It is not necessary to install anything to a harddisk; you don't even need a harddisk to run it. Due to on-the-fly decompression Grml includes about 2.1 GB of software and documentation on the CD. 

Grml provides more than 2500 software packages. Excluding library stuff, more than 1700 packages remain. We don't ship KDE and OpenOffice, but more than 800 packages which for example Knoppix does not provide. You'll get sysadmin's favourite tools, security- and network-related software, data recovery- and forensic-tools, many editors, shells, and of course many texttools. Choose between different flavours (grml, grml-medium and grml-small) and a x86 and a amd64 version depending on your needs.

Grml provides several scripts and utils which make life easier. The default interactive shell is Zsh and is configured with a very powerful setup, including a nifty completion mechanism. grml-x is a wrapper for configuring and using the X window system. grml2usb is a tool for installing grml ISO(s) on a usb device for booting. grml-crypt is a program that provides an easy wrapper arround cryptsetup, mkfs, losetup and mount. grml-live is a build framework based on FAI (Fully Automatic Installation) for generating a grml and Debian based Linux Live system (CD/ISO). grml-tips provides useful tips and tricks for daily life on the command line. grml-vpn is a program to establish encrypted communication channels in a network, and so on...

(Debian based Linux Live-CD, check out grml.org):

• provides support for SW-RAID (mdadm) and LVM out of the box
• boot with 'grml ssh=passw0rd' -> a ssh server will be automatically started for remote access using the specified 'passw0rd' for user 'grml'
• if a device with label GRMLCFG is present (e.g. your USB drive) it will be automatically mounted and for automating tasks you can use a simple script named 'grml.sh' on it (which will be automatically executed if it's present)
• the tool grml-terminalserver provides easy setup of booting via network/PXE (if booting via CD/USB/... isn't an option for whatever reason)
• bootoption 'bootfrom=/dev/...' allows you to even mix booting from CD with USB :)

UBCD4Win 3.6

Source
Requires a valid Windows XP or 2003 license
Where To Download
www.ubcd4win.com/downloads.htm
How To Burn
www.ubcd4win.com/burn.htm
UBCD4Win Forums
www.ubcd4win.com/forum/
But here's a quick reference
Download and Build and then Burn the UBCD4Win to CD
Boot from the UBCD4Win newly created bootable disc
Plug in a USB Flash Drive, or empty CD / DVD (if requiring to backup your data)
There are a number of Programs from the UBCD4Win Start menu, see pics h e r e
Or use UBCD4Win's "My Computer" and back up data to your external USB drive
(Source) Features:
· Explorer as Shell (by Hilander999 & Joshua)
· Hashcheck received some updates to help speed it up
· BTS Drivers now have compatible LAN, WLAN, and graphics drivers.
· Mass Storage, LAN, and WLAN drivers are included in UBCD4Win, only
· Mass Storage & LAN are enabled
· VC++ 2008 Runtime, Avira 9 requires this
· New quot;cleanup toolsquot; section, noted as CT in added software
· New quot;dynamicquot; plugin for Kaspersky, handles versions 7 and 8.
· Compatible with XP and Vista 32/64 

UBCD4WIN 3.6.0 Windows 7 release notes

New Release
# Feature- Explorer as Shell (by Hilander999 & Joshua)
# Feature- Hashcheck received some updates to help speed it up
# Feature- BTS Drivers now have compatible LAN, WLAN, and graphics drivers. Mass Storage, LAN, and WLAN drivers are included in UBCD4Win, only Mass Storage & LAN are enabled
# Feature- VC++ 2008 Runtime, Avira 9 requires this
# Feature- New quot;cleanup toolsquot; section, noted as CT in added software
# Feature- New quot;dynamicquot; plugin for Kaspersky, handles versions 7 and 8. Compatible with XP and Vista 32/64
# Added- CT: ATF Cleaner
# Added- Autorun Eater
# Added- CT: AVG Remover
# Added- CT: ComboFix
# Added- Easeus Partition Master HE 3.0.2
# Added- Commercial: Easeus Partition Master Pro MulitBoot plugin
# Added- Commercial: Kaspersky Internet Security
# Added- MalwareBytes AntiMalware
# Added- NetCat (it's back!!)
# Added- CT: Norton Removal Tool
# Added- CT: SDFix
# Added- Vipre
# Updated- All Anti-Spyware and Anti-Virus definitions updated 4/19/09
# Updated- 7-zip 4.65
[ UBCD4WIN release history ]

BUT note the following caveats:

1. You need to build this disk before you need it! (i.e. before your system crashes)
2. The UBCD4Win build process steps are fairly straight-forward but may require considerable processing time to complete (depending on your system might run for 30-45+ minutes)
3. AND NOTE: I've found the process runs smoothly and without any problem if you start with a Microsoft install CD. But if you only have an OEM install CD (e.g. one from HP or Dell) the build will often fail
   • Another way to easily identify an OEM install disk is to look at the folders on your install CD. Open your installation CD with Explorer. If you see an OEM folder listed, it's an OEM install disk (and you may have problems building UBCD4Win). Otherwise, it should be a breeze!
4. I have not yet tried building UBCD4Win using an already installed system (vs. using an installation CD) but will report on it when i finally try that method as well

UBCD4Win

Source
Full Version 3.60 is: 269MB
Patch available for current version? NO
3.60 MD5 Hash: f83c81b5197f01dfd8ca00764474f453
3.50 MD5 Hash: caa4a227660a59e7a8cfedbcb0445426
The project is now ONE download, no need to download the Builder, our project files, and drivers. All needed files are included in ONE download, well unless I make mistakes.....then patches will be released. However, additional tools and options are available for download. Some are listed below but soon our UBCD4WinDownloads.com domain will home all of the additional tools and more.

BackTrack Linux

Netstumbler is out!
BackTrack Linux - Penetration Testing Distribution
Back|Track LiveCD Blog

Download the ISO of the Linux liveCD, burn it or use in a startable USB flash memory and try running it on your laptop and see if your usb wireless adapter works with these killer applications.
You can be able to crack your own router with a very strong WEP key after capturing about 50,000 IPV4 packets. 
It is possible to crack a weak WEP key on a router in less than 3 minutes

Helix3 (Pro)

Source

As expected, e-fense is moving to a commercial business model with their Helix3 Pro and no free support or user's forum will be available to Helix users from 2 February 2009.
To get access to Helix support and forum e-fense is introducing the membership for $19.95 a month or $239 a year. It is not very clear at this stage; whether Helix3 Pro will be available for free download to non-members.

30 January 2009
Helix3 Pro will not be free!
Helix3 Enterprise

e-fense Inc. announces new management team
Helix3 vs Helix3 Pro
2 May 2009
E-fense decided to keep a free version of Helix3 alive
It can be downloaded here.
Helix is a ubuntu based linux distro that aims to help your work on Computer Forensic , Incident Response and Electronic Discovery. It almost has everything you need for your live forensic! By using Helix live cd , you can still boot into customized linux environment , that includes customized linux kernels, excellent hardware detection and many applications dedicated to Incident Response and Forensics !

helix3 live cd screenshot

Here’s the excerpt from their official site :

Helix has been modified very carefully to NOT touch the host computer in any way and it is forensically sound. Helix wil not auto mount swap space, or auto mount any attached devices. Helix also has a special live side for Incident Response and Forensics.

Helix focuses on Incident Response & Forensics tools. It is meant to be used by individuals who have a sound understanding of Incident Response and Forensic techniques.

Download Helix3 : http://www.e-fense.com/helix/Download.html
http://mirrors.cmich.edu/helix/Helix2008R1.iso
http://nebula.indocisc.co.id/~za/iso/ 

TestDisk Livecd

TestDisk on Live rescue CDs

Parted Magic

Parted Magic info and revision
Downloads--> torrent, LiveCD, liveUSB, PXE, otro vínculo
Distribution
HOWTO: Integrate Gparted into UBCD
por si falta algo...
DOS en USB

GnuPartEd

GnuParted Live CD
Educastur.es
sourceforge1 es diferente a sourceforge2
GPARTED-CLONEZILLA LiveCD

LiveUSB

Since 0.3.4-x version, GParted LiveUSB can be created from the iso LiveCD.
So there is no need to download another file !

To use the LiveUSB,

-either download this file in the directory where you have downloaded the iso file,
untar it (tar -xjf set_usb.sh.tar.bz2), become root and run it (sh set_usb.sh),

-either follow these simple instuctions (before 0.3.4-3):

(1) Create a fat16 partition on the usb stick and make sure it's flagged "boot".

(2) Copy from the livecd all the files from isolinux and syslinux directories
and gparted.dat file too, to the usb key.

(3) UMOUNT the usb stick and execute this command:
syslinux -s /dev/sda1
(imagine sda1 is the partition of your usb key ; but it could be something else such as sdb1.

You may find a complete description of the steps to follow at the forum !

-either follow these simple instuctions (since 0.3.4-3):

The second step is a bit different since there is no more isolinux directory !
You need to copy gparted.dat, and both gparted and gparted.igz files from boot/ directory,
and also all the files in syslinux directory, to your usb-key.

Browse releases of the old LiveUSB version here