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)

Using text commands to merge file content

Let's start with something simple – which is merging file content. Of course, we are only discussing text content here as merging binary files would be pointless. Our goal is to learn how to use two commands – paste and cat – to do simple things, such as concatenation and merging line by line. Let's start!

Getting ready

We just need one Ubuntu and one CentOS machine for this recipe. Here, we are going to use cli1 and cli2 to master these commands.

How to do it…

Starting with the simplest command for this chapter – cat – let's see some examples of what it does. If we type in a command such as cat filename.txt – if a file named filename.txt exists – we are going to get the content of that file on display. Let's check an example of this:

Figure 8.1 – Using the cat command on a text file

So, we used the cat command to show the...