Hi, I have a file called disk.dat that has a whole Linux filesystem on it and I'd like to know how to extract it so that I can edit that filesystem. I'd then like to know how to once again create that .dat again.

This is what the file is actually reported as:
> # file disk.dat
disk.dat: Linux rev 1.0 ext2 filesystem data
Any chance I can open that thing up on my non ext2 filesystem (I think I have reiserfs on here) and make changes, then compact that all back into an ext2 .dat file?