Process is a program in execution.

1. Program: usually binary program, which is placed in the storage medium (such as hard disk, optical disc, magnetic tape, etc.) and exists in the form of physical file;


2. Process: after the program is triggered, the permissions and attributes of the executor and the data required by the program code will be loaded into the memory. The operating system gives these memory units an identification code (PID). It can be said that a process is a running program.

 

As a process executes, it changes state

new:  The process is being created

running:  Instructions are being executed

waiting:  The process is waiting for some event to occur

ready:  The process is waiting to be assigned to a process

terminated:  The process has finished execution

 

Because the whole process can be clearly summarized into five states.

 

Information associated with each process

Process state

Program counter

CPU registers

CPU scheduling information

Memory-management information

Accounting information

I/O status information