Linux Shell Scripting Essentials

Learn shell scripting to solve complex shell-related problems and to efficiently automate your day-to-day tasks About This Book Familiarize yourself with the terminal by learning about powerful shell features Automate tasks by writing shell scripts for repetitive work Packed with easy-to-follow, hands-on examples to help you write any type of shell script with confidence Who This Book Is For This book is aimed at administrators and those who have a basic knowledge of shell scripting and who want to learn how to get the most out of writing shell scripts. What You Will Learn Write effective shell scripts easily Perform search operations and manipulate large text data with a single shell command Modularize reusable shell scripts by creating shell libraries Redirect input, output, and errors of a command or script execution to other streams Debug code with different shell debugging techniques to make your scripts bug-free Manage processes, along with the environment variables needed to execute them properly Execute and embed other languages in your scripts Manage creation, deletion, and search operations in files In Detail Shell scripting is a quick method to prototype complex applications or problems. Shell scripts are a collection of commands to automate tasks, usually those for which the user has a repeated need, when working on Linux-based systems. Using simple commands or a combination of them in a shell can solve complex problems easily. This book starts with the basics, including essential commands that can be executed on Linux systems to perform tasks within a few nanoseconds. You'll learn to use outputs from commands and transform them to show the data you require. Discover how to write shell scripts easily, execute script files, debug, and handle errors. Next, you'll explore environment variables in shell programming and learn how to customize them and add a new environment. Finally, the book walks you through processes and how these interact with your shell scripts, along with how to use scripts to automate tasks and how to embed other languages and execute them. Style and approach This book is a pragmatic guide to writing efficient shell programs, complete with hands-on examples and tips.

Create and maintain powerful Bash scripts for automation and administration. Key FeaturesGet up and running with Linux shell scripting using real-world examplesLeverage command-line techniques and methodologies to automate common yet complex administration tasksA practical guide with exposure to scripting constructs and common scripting patternsBook Description Shell scripts allow us to program commands in chains and have the system execute them as a scripted event, just like batch files. This book will start with an overview of Linux and Bash shell scripting, and then quickly deep dive into helping you set up your local environment, before introducing you to tools that are used to write shell scripts. The next set of chapters will focus on helping you understand Linux under the hood and what Bash provides the user. Soon, you will have embarked on your journey along the command line. You will now begin writing actual scripts instead of commands, and will be introduced to practical applications for scripts. The final set of chapters will deep dive into the more advanced topics in shell scripting. These advanced topics will take you from simple scripts to reusable, valuable programs that exist in the real world. The final chapter will leave you with some handy tips and tricks and, as regards the most frequently used commands, a cheat sheet containing the most interesting flags and options will also be provided. After completing this book, you should feel confident about starting your own shell scripting projects, no matter how simple or complex the task previously seemed. We aim to teach you how to script and what to consider, to complement the clear-cut patterns that you can use in your daily scripting challenges. What you will learnUnderstand Linux and Bash basics as well as shell scripting fundamentalsLearn to write simple shell scripts that interact with Linux operating systemBuild, maintain, and deploy scripts in a Linux environmentLearn best practices for writing shell scriptsAvoid common pitfalls associated with Bash scriptingGain experience and the right toolset to write your own complex shell scriptsWho this book is for This book targets new and existing Linux system administrators, Windows system administrators or developers who are interested in automating administrative tasks. No prior shell scripting experience is needed but in case you do this book will make a pro quickly. Readers should have a basic understanding of the command line.

Unleash the power of shell scripts to solve real-world problems by breaking through the practice of writing tedious code About This Book 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 Who This Book Is For This book is ideal for those who are proficient at working with Linux and who want to learn about shell scripting to improve their efficiency and practical skills. By the end of this book, you will be able to confidently use your own shell scripts in the real world. 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 In Detail 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. Style and approach This practical book will go from the very basics of shell scripting to complex, customized automation. The idea behind this book is to be as practical as possible and give you the look and feel of what real-world scripting is like.

Master the complexities of Bash shell scripting and unlock the power of shell for your enterprise Key Features Identify high-level steps such as verifying user input Using the command line and conditional statements in creating/executing simple shell scripts Create and edit dynamic shell scripts to manage complex and repetitive tasks Leverage the command-line to bypass GUI and automate common tasks Book Description In this book, you’ll discover everything you need to know to master shell scripting and make informed choices about the elements you employ. Grab your favorite editor and start writing your best Bash scripts step by step. Get to grips with the fundamentals of creating and running a script in normal mode, and in debug mode. Learn about various conditional statements' code snippets, and realize the power of repetition and loops in your shell script. You will also learn to write complex shell scripts. This book will also deep dive into file system administration, directories, and system administration like networking, process management, user authentications, and package installation and regular expressions. Towards the end of the book, you will learn how to use Python as a BASH Scripting alternative. By the end of this book, you will know shell scripts at the snap of your fingers and will be able to automate and communicate with your system with keyboard expressions. What you will learn Make, execute, and debug your first Bash script Create interactive scripts that prompt for user input Foster menu structures for operators with little command-line experience Develop scripts that dynamically edit web configuration files to produce a new virtual host Write scripts that use AWK to search and reports on log files Draft effective scripts using functions as building blocks, reducing maintenance and build time Make informed choices by comparing different script languages such as Python with BASH Who this book is for If you are a Linux administrator or a system administrator and are interested in automating tasks in your daily lives, saving time and effort, this book is for you. Basic shell scripting and command-line experience will be required. Familiarity with the tasks you need to automate will be helpful.

A quick and straightforward approach to writing shell scripts to accomplish different types of tasks on a Linux system. About This Book Understand expressions and variables and how to use them practically Familiarize yourself with the various text filtering tools available in Linux A fast-paced and concise guide that gets you well versed with linux shell scripting. Who This Book Is For This book is for both GNU/Linux users who want to do amazing things with the shell and for advanced users looking for ways to make their lives with the shell more productive. What You Will Learn Get acquainted with the basics of a shell script to serve as a refresher for more advanced topics Learn different ways to create and run a script Discuss the passing and verification of parameters, along with the verification of other items. Understand the different forms of conditions and loops, and go over the sleep command in detail Learn about different ways to handle the reporting of return codes Create an interactive script by reading the keyboard and use subroutines and interrupts Create scripts to perform backups and go over the use of encryption tools and checksums Use wget and curl in scripts to get data directly from the Internet In Detail Linux Shell Scripting Bootcamp is all about learning the essentials of script creation, validating parameters, and checking for the existence of files and other items needed by the script. We will use scripts to explore iterative operations using loops and learn different types of loop statements, with their differences. Along with this, we will also create a numbered backup script for backup files. Further, you will get well-versed with how variables work on a Linux system and how they relate to scripts. You'll also learn how to create and call subroutines in a script and create interactive scripts. The most important archive commands, zip and tar, are also discussed for performing backups. Later, you will dive deeper by understanding the use of wget and curl scripts and the use of checksum and file encryption in further chapters. Finally, you will learn how to debug scripts and scripting best practices that will enable you to write a great code every time! By the end of the book, you will be able to write shell scripts that can dig data from the web and process it efficiently. Style and approach This book is all about fast and intensive learning. This means we don't waste time in helping readers get started. The new content is basically about filling in with highly-effective examples to build new things, solving problems in newer and unseen ways, and solving real-world examples.

Advance your understanding of the Linux command line with this invaluable resource Linux Command Line and Shell Scripting Bible, 4th Edition is the newest installment in the indispensable series known to Linux developers all over the world. Packed with concrete strategies and practical tips, the latest edition includes brand-new content covering: Understanding the Shell Writing Simple Script Utilities Producing Database, Web & Email Scripts Creating Fun Little Shell Scripts Written by accomplished Linux professionals Christine Bresnahan and Richard Blum, Linux Command Line and Shell Scripting Bible, 4th Edition teaches readers the fundamentals and advanced topics necessary for a comprehensive understanding of shell scripting in Linux. The book is filled with real-world examples and usable scripts, helping readers navigate the challenging Linux environment with ease and convenience. The book is perfect for anyone who uses Linux at home or in the office and will quickly find a place on every Linux enthusiast’s bookshelf.

Break through the practice of writing tedious code with shell scripts Key Features Learn to impeccably build shell scripts and develop advanced applications Create smart solutions by writing and debugging scripts A step-by-step tutorial to automate routine tasks by developing scripts Book Description Linux is the most powerful and universally adopted OS. 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 reads this file and acts on commands as if they were typed on the keyboard. Learning Linux Shell Scripting covers Bash, GNU Bourne Again Shell, preparing you to work in the exciting world of Linux shell scripting. CentOS is a popular rpm-based stable and secured Linux distribution. Therefore, we have used CentOS distribution instead of Ubuntu distribution. Linux Shell Scripting is independent of Linux distributions, but we have covered both types of distros. We start with an introduction to the Shell environment and basic commands used. Next, we explore process management in Linux OS, real-world essentials such as debugging and perform Shell arithmetic fluently. You'll then take a step ahead and learn new and advanced topics in Shell scripting, such as decision making, starting up a system, and customizing a Linux environment. You will also learn about grep, stream editor, and AWK, which are very powerful text filters and editors. Finally, you'll get to grips with taking backup, using other language scripts in Shell Scripts as well as automating database administration tasks for MySQL and Oracle. By the end of this book, you will be able to confidently use your own shell scripts in the real world. What you will learn Familiarize yourself with the various text filtering tools available in Linux 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, dialogs to develop screens & Database administration such as MySQL or Oracle Start up a system and customize a Linux system Taking backup of local or remote data or important files. Use existing other language scripts such as Python, Perl & Ruby in Shell Scripts Who this book is for Learning Linux Shell Scripting is ideal for those who are proficient at working with Linux and want to learn about shell scripting to improve their efficiency and practical skills.