Book Image

Linux Shell Scripting Essentials

By : Sinny Kumari, Khem Raj
Book Image

Linux Shell Scripting Essentials

By: Sinny Kumari, Khem Raj

Overview of this book

Table of Contents (15 chapters)
Linux Shell Scripting Essentials
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Signals


A signal is a software interrupt to notify processes that an external event has occurred. In a normal execution, processes keeps running as expected. Now, for some reason, a user may want to cancel a running process. When the process is started from a terminal, it will terminate when we hit the Ctrl + c keys or run the kill command.

When we press Ctrl + c keys while process is running in a terminal, a signal SIGINT is generated and sent to the process running in foreground. Also, when the kill command is called on process, the SIGKILL signal is generated and the process is terminated.

Available signals

Among all available signals, we will discuss the frequently used signals here:

Signal name

Value

Default Action

Description

SIGHUP

1

Term

This signal is used to Hangup or death of controlling process

SIGINT

2

Term

This signal is used to interrupt from keyboard like ctrl + c, ctrl + z

SIGQUIT

3

Core

This signal is used to quit from keyboard

SIGILL

4

Core

It is used to...