linux

Introduction

Signals are a notification mechanism among processes, they can be either termination or warning signals, that allow process coordination and monitoring

Objectives

• Explain what signals are and how they are used
• Know the different signals and types of signals available in Linux
• Use kill, killall and pkill to send signals from the command line

What signals are

They are a inter process communication (IPC) mechanism used to notify process about asynchronous events (or exceptions).

Introduction

A process is the embodiment of a running application which may or may not consist of multiple threads. Processes have both attributes and well-delineated permissions. They must be in one of a number of enumerated states, the most common of which are running or sleeping. It is important to know when a process is running in user mode with limited privilege, or in kernel mode with enhanced priviledges, including more direct access to hardware. There are a number of different ways to create child processes and to set and modify their priorities.