IT 1100 : Introduction to Operating Systems

Chapter 10 Processes


Processes

Modern operating systems are usually multitasking, meaning that they create the illusion of doing more than one thing at once by rapidly switching from one executing program to another. The Linux kernel manages this through the use of processes. Processes are how Linux organizes the different programs waiting for their turn at the CPU.


Processes

init - Receives PID of 1. program that runs when Linux starts. init will launch several processes and call init scritps.

Many of these services are called daemons… or programs that run in the background without having any user inteface.

A process can launch another process - the new process is said to be a child process of the parent.


Processes

Each process is assigned an ID number so that the kernel can keep track of the process. (PID or Process ID). Init always get PID of 1. PIDs also have an associated UID.


Processes (Process Related Commands)


Process States

A process can be in one of several states:


Process key commands


ps options


Killing


shutdown options

System Shutdown and Restart commands

   shutdown -r time message 

Example: sudo shutdown -r +5 “Server will restart in 5 minutes. Please save your work.” Example: sudo shutdown -h now


shutdown options

Example: sudo halt Example: sudo reboot

Last Updated 03/05/2018