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Learning Linux Shell Scripting

Chapter 2. Drilling Deep into Process Management, Job Control, and Automation

In the last chapter, we introduced ourselves to the Bash shell environment in Linux. You learned basic commands and wrote your first Shell script as well.

You also learned about process management and job control. This information will be very useful for system administrators in automation and solving many problems.

In this chapter, we will cover the following topics:

Monitoring processes with ps
Job management—working with fg, bg, jobs, and kill
Exploring at and crontab

Key benefits

Learn how to efficiently and effectively build shell scripts and develop advanced applications with this handy book

Develop high quality and efficient solutions by writing professional and real-world scripts, and debug scripts by checking and shell tracing

A step-by-step tutorial to automate routine tasks by developing scripts from a basic level to very advanced functionality

Description

Linux is the one of the most powerful and universally adopted OSes. Shell is a program that gives the user direct interaction with the operating system. Scripts are collections of commands that are stored in a file. The shell can read this file and act on the commands as if they were typed on the keyboard. Shell scripting is used to automate day-to-day administration, and for testing or product development tasks. This book covers Bash, GNU Bourne Again SHell, preparing you to work in the exciting world of Linux shell scripting. We start with an introduction to the Shell environment and explain basic commands used in Shell. Next we move on to check, kill, and control the execution of processes in Linux OS. Further, we teach you about the filter tools available in Linux and explain standard output and standard errors devices. Then we will ensure you understand Shell’s interpretation of commands and get a firmer grasp so you use them in practice. Next, you’ll experience some real-world essentials such as debugging and perform Shell arithmetic fluently. Then you’ll take a step ahead and learn new and advanced topics in Shell scripting, such as starting up a system and customizing a Linux system. Finally, you’ll get to understand the capabilities of scripting and learn about Grep, Stream Editor, and Awk.

What you will learn

Familiarize yourself with the various text filtering tools available in Linux

Combine the fundamental text and file processing commands to process data and automate repetitive tasks

Understand expressions and variables and how to use them practically

Automate decision-making and save a lot of time and effort of revisiting code

Get to grips with advanced functionality such as using traps and signals and using dialogs to develop screens

Start up a system and customize a Linux system

Take an in-depth look at regular expressions and pattern matching to understand the capabilities of scripting

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Instant access to your Digital eBook purchase

Download this book in EPUB and PDF formats

Access this title in our online reader with advanced features

DRM FREE - Read whenever, wherever and however you want

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Andras Pasztirak Feb 02, 2016

One of the better, more comprehensive guides on the topic of shell scripting I've ever seen. It goes through all the necessary basics and dwells into the more advanced topics but in a way that the pacing is great, easy to follow, not jarring. The chapters are built up logically for the most part, the one tiny gripe I'd have is that regular expressions are only brought up in the very last chapter, I feel they should be featured a lot earlier in the book as they are an integral part of scripts and command line work. Still, I don't think that's enough reason to deprive it of 5 stars.I'd highly recommend this ebook for either a complete beginner in shell scripting or someone who has experience in the field but is looking to refresh their memory, perhaps after not touching the shell after a long time.

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Laurent Jan 06, 2016

This book is well structured about shell scripting used to manage daily tasks on a Linux computer.Of course it is more for people likes terminal.A very good book to grow up your knowledge of this intimacy with the essential tools of shell.

Andrea Jan 31, 2016

For sure is not the only book about shell scripting (books on this topic have started since '70 years), but it's really good and with a step by step approach.You start learning some common Unix commands (included some Unix/Linux concepts), the job control, the text filtering features.With all this basis you start build some scripts using variables, flows, conditions.Several tricks are included and also several examples.Finally it's included also a part to build text based window interface with dialog.Considering that shell scripting is still used (also if languages like Perl, Ptyton, Ruby can totally replace them), this book is really useful for Linux/Unix system administrator and people that need to learn on how programming with shell script language.

CC Dec 03, 2017

I LOVE this book!!! Ganesh takes the time to explain and give examples on almost everything. Give it a read and you will not regret it. Thank you to Ganesh and all who have contributed to a totally AWESOME book! Please keep writing!!!

adnan baloch Jan 15, 2016

This book is borne out of the author's own experiences over the years solving day to day problems in his work. That should give anyone confidence that the examples in this book are as real-world as they can be. Veterans from the DOS days will fondly remember creating batch files to accomplish a myriad of tasks. If you are one of them and switched to an OS like Unix or Linux, this is the book to get. Everything from file permissions, process management, task scheduling, text processing to interactive shell scripting is covered here. Want to backup a folder in the middle of the night and want its status emailed to you? Check. Have a complex operation in mind involving loops, file handling, arrays, functions and message dialogs? The author arms you with the necessary information to achieve that. The final chapters take the readers through understanding the Linux startup process and customizing the system environment as well as using regular expressions for complex pattern matching. Apart from networking, this book is all you need to handle common Linux system admin duties.

Learning Linux Shell Scripting: Unleash the power of shell scripts to solve real-world problems by breaking through the practice of writing tedious code

What do you get with eBook?

Learning Linux Shell Scripting

Chapter 2. Drilling Deep into Process Management, Job Control, and Automation

Introducing process basics

Monitoring processes using ps

Process management

Process monitoring tools – top, iostat, and vmstat

Understanding "at"

Introducing process basics

Monitoring processes using ps

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