Book Image

Linux Command Line and Shell Scripting Techniques

By : Vedran Dakic, Jasmin Redzepagic
Book Image

Linux Command Line and Shell Scripting Techniques

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)

Parsing date and time data

Working with time-based data is often less than fun, especially when you're working with a lot of time-based content. But for our use cases, we often use date/time information for indexing; that is, to name our backup files and similar purposes. So, learning how to get information from the date command and putting that information into variables so that our code can be as modular as possible is very important. Let's create a shell script that we are going to be able to use in future scripts as a snippet of code for a lot of our shell scripts – at least bits and pieces of it.

Getting ready

We don't need any special utilities to be installed, just our Linux machine to be alive and ready for action.

How to do it…

We are going to go back to the basics and use the date command to extract all of the date and time pieces that we'll ever need:

  • Information about the current time in terms of hours, minutes, and...