Download - Saving Your Ass(ets) with chroot
Saving Your Ass(ets) with chroot
Alan Bailward <[email protected]>April 15, 2004
For the Fraser Valley Linux Users Group
What is chroot?
Allows running of commands with an arbitrary root directory
Syntax: chroot NEWROOT [command]
Used to “jail” applications
Mostly used for security applications
i.e.: servers
Getting in Trouble
Easy to have Linux problems
Errors on install
Broken kernel
Broken lilo
Normally you’re out of luck, to a degree, or need to deal with accessing things from a BootCD
Getting Out of Trouble
The old way
The Old way
Get to your system
Floppy
BootCD
Fix it
Mess with lilo/lilo.conf
Compile kernel, hope it works
Getting Out of Trouble
The New Way
Using chroot
Lets you access your system as it was
Full access to accurate /proc and /dev
No funky pathing
Easy to jump in and out of
How To Use chroot 1
Boot with BootCD
mkdir /mnt/new
mount /dev/hda1 /mnt/new
mount /dev/hda2 /mnt/new/boot
mount /dev/hda3 /mnt/new/var
How To Use chroot 2
mount -o bind /proc /mnt/new/proc/
link the “real” /proc into your new file structure
mount -o bind /dev /mnt/new/dev/
ditto for /dev (only for devfs systems)
How To Use chroot 3
cp /etc/resolv.conf /mnt/new/etc/
need accurate network info
chroot /mnt/new /bin/bash
enter the system
env-update # gentoo only
update environment settings
How To Use chroot 4
You are now in a shell that is your old system
cd / puts you in your old / (really /mnt/new/)
Can run lilo, compile kernels, etc
To exit, type ‘exit’ to exit, then unmount disks and reboot
Live Demo
Questions?