Upgrade a USB-stick contained system

[Lowell Gilbert]

Steve Bertrand <steve at ibctech.ca> writes:

> I run numerous systems (mostly networking gear) from 2GB USB thumb
> sticks. These systems do not have hard disks.
>
> To update one of these systems, I'd generally copy the thumb drive
> filesystem to a hard disk in another PC, upgrade it, and then transfer
> the necessary data back to the USB drive. I'd like to change this approach.
>
> What I'd like to do, is boot the USB drive in another machine that has a
> hard drive, and mount any necessary directories for the duration of the
> upgrade into the USB drive (such as /usr/src, /usr/ports etc) from the
> hard drive. When I'm done, the cruft stays on the physical hard disk,
> while the upgraded system on the USB drive is physically replaced back
> into the original system.
>
> This is purely a disk-space issue on the USB disk. What I want to know,
> is *exactly* what _working_ directories/filesystems are required to
> build a new system... working directories that can be dissolved with no
> repercussions by using umount.

For the base system, /usr/src and /usr/obj.
For ports, /usr/ports.

They can be mounted in other places and pointed at with variables, but
there's no reason not to use the standard places for this application.

-- 
Lowell Gilbert, embedded/networking software engineer, Boston area
		http://be-well.ilk.org/~lowell/