Classnotes | UNIX02 | RecentChanges | Preferences chroot is one of those staggeringly versatile commands under UNIX that almost no one uses fully. chroot runs a command or interactive shell from a special root directory. What does this mean?
Well, perhaps I should give an example. Let's say you have a directory tree under UNIX like the following:
And that under /target, you have a complete installation of standard UNIX files. You could use chroot to place yourself into the directory tree under /target and you would not see the other files on the system. In other words, by issuing this command:
# chroot /target
Your directory tree starting with root would look like this:
and you would be inside /target, but without the option to leave target.
Why is something like this useful? There's actually many reasons, but a few worth mentionning are:
Application install or setup from a rescue CD (this is what we will be doing next)
Limitting users or specific applications with respect to what they can do on a system (this will be covered in UNIX03, but by way of a preview, imagine limitting a ftp daemon such that no one who compromises that daemon can harm anything on your system).
Operating system install (this is employed in the standard Gentoo Linux installation).