Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Overview of this book

The shell remains one of the most powerful tools on a computer system — yet a large number of users are unaware of how much one can accomplish with it. Using a combination of simple commands, we will see how to solve complex problems in day to day computer usage.Linux Shell Scripting Cookbook, Second Edition will take you through useful real-world recipes designed to make your daily life easy when working with the shell. The book shows the reader how to effectively use the shell to accomplish complex tasks with ease.The book discusses basics of using the shell, general commands and proceeds to show the reader how to use them to perform complex tasks with ease.Starting with the basics of the shell, we will learn simple commands with their usages allowing us to perform operations on files of different kind. The book then proceeds to explain text processing, web interaction and concludes with backups, monitoring and other sysadmin tasks.Linux Shell Scripting Cookbook, Second Edition serves as an excellent guide to solving day to day problems using the shell and few powerful commands together to create solutions.
Table of Contents (16 chapters)
Linux Shell Scripting Cookbook
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Killing processes and send or respond to signals


Termination of processes is an important task we always come across, including the need to terminate all the instances of a program. The command line provides several options for terminating programs. An important concept regarding processes in Unix-like environments is that of signals . Signals are an inter-process communication mechanism used to interrupt a running process to perform some action. Termination of a program is also performed by using the same technique. This recipe is an introduction to signals and their usage.

Getting ready

Signals are an inter-process mechanism available in Linux. We can interrupt a process using a specific signal, which is associated with an integer value. When a process receives a signal, it responds by executing a signal handler. It is possible to send and receive signals and respond according to the signals in shell scripts as well. KILL is a signal used to terminate a process. The events such as Ctrl ...