Ubuntu

I have created a thumbdrive with a bootable version of Ubuntu 10.04 LTS, it uses Grub legacy.

One of the issues I have is that everytime I boot a new system from the thumbdrive, it writes entries for the partitions in the fstab. Consequently, when I boot another system, the OS reads the fstab and tries to mount partitions that don't exist on the new system. I can simply manually edit the fstab before I shutdown the system, but want to automate this. I have looked at startup and shutdown scripts but they appear to be stopping and starting services. So my questions are:
Is a shutdown script the most appropriate way to re-write the fstab on shutdown?
If not, what is the most appropriate way and how should I implement it?

TIA

Stumpy

I may not be understanding your question. Why are you using the same fstab for a different system?

I'll try and explain. Machine A has 2 hard disks with a total of 4 partitions, I boot machine A with my thumbdrive, the O/S automatically writes an fstab reflecting the partitions on machine A. Machine B has one hard disk containing a single partition, I boot machine B with my thumbdrive, the O/S reads the fstab (that reflects the partitions on Machine A) and tries to mount 4 partitions, thus throwing up errors. I want to automatically re-write the fstab (containing just a single line for /proc) when I shutdown a system to prevent the behaviour described.