if i am running a C program using gcc compiler in linux, then where does the temporary variables are being stored. and how can we access them?

in short:
1) you use gcc to compile your code into an executable
2) you maybe use a shell to run your executable by a process that comprises a stack area
3) the temporary variables that were declared inside the functions of your code will be created and destroyed inside the process stack by the entry/exit code created at step 1.

cicorino is correct, please tell us what you are try to do/achieve

Every time you "run a program," a process is created ... which represents "an instance of a currently-running program." (That's what a 'process' is.)

Each process "owns" all of the memory that is assigned to it, which it basically uses for one of three purposes:

1. "The stack," which is where local variables live.
2. Global-variable storage, which is allocated once when the program starts and remains for the life of the program.
3. "The heap," which is where dynamically allocated storage blocks (should there be any) come from.

This is true for any modern operating system.

If a process wishes to share memory with any other process, it must allocate a "shared memory segment," which (by suitable operating-system magic...) will be made to appear within the virtual-memory space of each process at the same time. Otherwise, the read/write storage of each process is absolutely isolated from all others, even when the (virtual...) addresses are the same.

actually i have to build mpi library using which we can execute parallel programs in a cluster. whenever there is a failure of node its execution gets wasted, so to save this problem we store all that variables and from where the execution should start to some reliable source using some algorithm so that after failure we can extract those values and resume from where we got the failure.

You'll have to write your state information out to a hard drive that is accessible to the cluster. Then in the event of a failure, another node can read in the state information and resume from the state that the failed one last wrote prior to the failure.