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Linux Command Line and Shell Scripting Techniques

Linux Command Line and Shell Scripting Techniques

By : Vedran Dakic, Jasmin Redzepagic
4.4 (5)
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Linux Command Line and Shell Scripting Techniques

Linux Command Line and Shell Scripting Techniques

4.4 (5)
By: Vedran Dakic, Jasmin Redzepagic

Overview of this book

Linux Command Line and Shell Scripting Techniques begins by taking you through the basics of the shell and command-line utilities. You’ll start by exploring shell commands for file, directory, service, package, and process management. Next, you’ll learn about networking - network, firewall and DNS client configuration, ssh, scp, rsync, and vsftpd, as well as some network troubleshooting tools. You’ll also focus on using the command line to find and manipulate text content, via commands such as cut, egrep, and sed. As you progress, you'll learn how to use shell scripting. You’ll understand the basics - input and output, along with various programming concepts such as loops, variables, arguments, functions, and arrays. Later, you’ll learn about shell script interaction and troubleshooting, before covering a wide range of examples of complete shell scripts, varying from network and firewall configuration, through to backup and concepts for creating live environments. This includes examples of performing scripted virtual machine installation and administration, LAMP (Linux, Apache, MySQL, PHP) stack provisioning and bulk user creation for testing environments. By the end of this Linux book, you’ll have gained the knowledge and confidence you need to use shell and command-line scripts.
Table of Contents (19 chapters)
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Working with returns from a function

We mentioned that it is possible to use global variables to pass values to the functions inside a script and to get results back. This is the worst possible way to do it. If we need to pass some value to a function, using arguments is the way it should be done. The problem that we still have is how to get the results back when the function finishes. We are going to solve that in this recipe.

Getting ready

If nothing else, bash is logical and consistent in the syntax it uses. The reason we are mentioning this is that when functions return a value, they use the exact same mechanism that scripts use when returning a variable—the return command. Using this command, it is possible for a function to return a value when called, but the value can be in the range of numbers between 0 and 255. There is also a possibility to set a global variable just to return a function value—for example, if we need to return a string—but try...

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