In Unix, a process is a running program and the abstract object that creates the operating system to manage access to that program to System resources (memory, CPU, device I /O).
There can be multiple instances of the same program running simultaneously.
Each one is a different process.
Unix is a multiprocessing system for time-sharing.
The operating system that rotates the processor usage at short intervals between theprocesses defined in the system so that it creates the illusion that all advancesimultaneously.
A process consists of code, data and stack.Processes exist in a tree hierarchy(various children, a single parent).The system assigns a process ID(PID) only to start the process.The