Book Image

Mastering Bash

By : Giorgio Zarrelli
Book Image

Mastering Bash

By: Giorgio Zarrelli

Overview of this book

System administration is an everyday effort that involves a lot of tedious tasks, and devious pits. Knowing your environment is the key to unleashing the most powerful solution that will make your life easy as an administrator, and show you the path to new heights. Bash is your Swiss army knife to set up your working or home environment as you want, when you want. This book will enable you to customize your system step by step, making your own real, virtual, home out of it. The journey will take you swiftly through the basis of the shell programming in Bash to more interesting and challenging tasks. You will be introduced to one of the most famous open source monitoring systems—Nagios, and write complex programs with it in any languages. You’ll see how to perform checks on your sites and applications. Moving on, you’ll discover how to write your own daemons so you can create your services and take advantage of inter-process communication to let your scripts talk to each other. So, despite these being everyday tasks, you’ll have a lot of fun on the way. By the end of the book, you will have gained advanced knowledge of Bash that will help you automate routine tasks and manage your systems.
Table of Contents (15 chapters)

Job controls

So, we have the job ID, process ID, foreground, and background processes, but how do we control these jobs? We have a bunch of commands available, let's have a look at how to use them:

  • kill: We can pass the job ID to this command, which will send the SIGTERM signal to all the processes belonging to the job itself:
zarrelli:~$ sleep 100 &
[1] 9909
zarrelli:~$ kill %1
zarrelli:~$
[1]+ Terminated sleep 100

You can also pass to kill a specific signal to send to the process. For instance, kill -15 will nicely terminate a process with a SIGTERM signal, and if it refuses to die, kill -9 will send a SIGKILL, which will instantly terminate a process.
Which signals can we send to a process? Either
kill -l or cat /usr/include/asm-generic/signal.h will give us a list of all the signals supported.

  • killall: If we know what is the name of the process, the easiest way to...