Book Image

Learn Linux Quickly

By : Ahmed AlKabary
Book Image

Learn Linux Quickly

By: Ahmed AlKabary

Overview of this book

Linux is one of the most sought-after skills in the IT industry, with jobs involving Linux being increasingly in demand. Linux is by far the most popular operating system deployed in both public and private clouds; it is the processing power behind the majority of IoT and embedded devices. Do you use a mobile device that runs on Android? Even Android is a Linux distribution. This Linux book is a practical guide that lets you explore the power of the Linux command-line interface. Starting with the history of Linux, you'll quickly progress to the Linux filesystem hierarchy and learn a variety of basic Linux commands. You'll then understand how to make use of the extensive Linux documentation and help tools. The book shows you how to manage users and groups and takes you through the process of installing and managing software on Linux systems. As you advance, you'll discover how you can interact with Linux processes and troubleshoot network problems before learning the art of writing bash scripts and automating administrative tasks with Cron jobs. In addition to this, you'll get to create your own Linux commands and analyze various disk management techniques. By the end of this book, you'll have gained the Linux skills required to become an efficient Linux system administrator and be able to manage and work productively on Linux systems.
Table of Contents (24 chapters)

Bash script functions

When your scripts get bigger and bigger, things can get very messy. To overcome this problem, you can use bash functions. The idea behind functions is that you can reuse parts of your scripts, which in turn produces better organized and readable scripts.

The general syntax of a bash function is as follows:

function_name () {
<commands>
}

Let's create a function named hello that prints out the line "Hello World". We will put the hello function in a new script named fun1.sh:

elliot@ubuntu-linux:~$ cat fun1.sh 
#!/bin/bash

hello () {
echo "Hello World"
}

hello # Call the function hello()
hello # Call the function hello()
hello # Call the function hello()

Now make the script executable and run it:

elliot@ubuntu-linux:~$ chmod a+x fun1.sh 
elliot@ubuntu-linux:~$ ./fun1.sh
Hello World
Hello World
Hello World

The script outputs the line "Hello World" three times to the terminal. Notice that we called (used) the function hello...