This article presents nFS, a portable library for emulating a file system within a file. This library has nothing to do with Linux's "NFS".

The library is compatible with MSVS/Win32, gcc/Linux and gcc/Solaris. It is written in C. However, because of its clean OOP-like structure, it is easily portable to C++.

Strictly speaking, for performance reasons, the external representation of the file system is made of two files, as described below; however, these two files always go together, and the library manipulates both at the same time. So, conceptually, the term "within a file" still applies to some extent.