Hi
If u create a shared memory using c in UNIX.
Where the memory will be created...
RAM or Hard disk...
In wikipedia :One process will create an area in RAM which other processes can access.
can u justify the above answer...
then what about swap portion and virtual memory.
If any good document u can refer me….

For the most part, Memory = RAM.

Swap storage is used only by the OS as temporary storage for memory segments which it deems to be dormant in some sense. This is part of the virtual memory system, and is not accessible by userland applications.

Normally, memory owned by one process is protected by the OS from access by other processes. Using a couple of different APIs, the OS can create, and otherwise manage, segments of memory which it will allow multiple processes to locate and access. Shared memory is one component of the general category of Interprocess Communication, IPC. A Google search for Interprocess Communication should lead to numerous educational documents.

--- rod.