Unix - UNIX Process States Explained

In UNIX, a process is a program that is currently being executed by the system. Every process goes through different states during its lifetime. Understanding process states helps in monitoring system performance and managing running applications effectively.

Running State
A process is in the running state when it is actively using the CPU for execution. At any given moment, only a limited number of processes can be in this state because CPU time is shared among processes.

Sleeping State
A process enters the sleeping state when it is waiting for an event, such as user input or data from disk. Sleeping processes do not use CPU resources until the required event occurs.

Stopped State
A process is in the stopped state when its execution is paused intentionally. This can happen when a user sends a stop signal or when the process is being debugged. The process remains in memory but does not run.

Zombie State
A zombie process is a process that has finished execution but still has an entry in the process table. This happens because the parent process has not yet collected the exit status of the child process.

Process Creation
Processes in UNIX are usually created using a system call that creates a child process from a parent process. The child process may enter different states depending on how it is scheduled and executed.

Process Termination
A process terminates after completing its task or when it is forced to stop. Once terminated, system resources used by the process are released except for minimal information kept temporarily for the parent process.

State Identification
Process states can be identified using system commands that display the current status of processes. These states help administrators understand what the system is doing at a given time.

Where It Is Used
Process state knowledge is used in system monitoring, performance tuning, troubleshooting, and managing multi-tasking environments.