UNIX for Advanced & Expert Users

Is there any way I can create a virtual file that is a subsection of another file? Similar to the way partitions are subsections of the disk device, but configurable and with a normal file source.

File overlays? Some old OSes had them. They could create a different "view" of files. I bumped into finnix a while back, which will create a filesystem with overlays for a mounted cd
See http://www.finnix.org/Overlays


However I don't think it is precisely what you want. What you want sounds like at least a specialty filesystem, if not kernel changes... can you tinker with mmap, you can mmap individual pages of a file?

Try a google on unix filesystem overlays. or mmap file overlay

Yeah, the trick is, I want to be able to mount part of a file. mmap's not going to cut it, I can't mount a memory segment. Thanks, I'll look into file overlays.