LINUX: Easy Linux For Beginners, Your Step-By-Step Guide to Learning The Linux Operating System and Command Line (2015)

vi Command	What it does
o	Type this in command mode to insert a new line and enter text
i	Type I to insert succeeding character to the left side of the cursor
u	Undo changes
ESC	To quit insert mode
:wq!	To save your changes and quit

Table 12: Sample vi keys

Have you chosen a text editor? Let’s now proceed to trying a simple script.

Simple Scripting

A script is a program that can be interpreted by a shell or a compiled program. We call them shell scripts in Linux because most scripts are run in bash or in any other shell (ksh, csh, bash).

Scripts are useful in automating and simplifying administrative tasks, log monitoring of the system, and data processing. To begin scripting, open a text file with vi or a text editor of your choice.

The first line in the file indicates which shell should be used to interpret the script.

#!/bin/sh

This indicates that the bourne shell should be used to interpret the script.

Let’s do a simple script. Enter the following lines of script. Save the file as simplescript.sh. Ensure that the file permission for the user is set to 744 so you can run the script.

#!/bin/sh

echo "My name is: $1"

echo I’m using Linux distro: $2

echo Today is: $3

Run the script along with 3 arguments:

./simplescript.sh Steve Fedora Tuesday

The output should be like this:

My name is: Steve

I’m using Linux distro: Fedora

Today is: Tuesday

Here’s an example of how you can use it in maintaining your computer’s performance. If you have already used 80% of your disk space, it might be good to check which files are the biggest in your computer.

Write a new script with the command below:

find / -type f -atime +30 -size +1000k -exec ls -l {} \; > /tmp/filecleanup

This shell script will generate a new file called fileCleanup containing a list of old and big files. As an administrator, the next step is to contact the file owners to give them a notice before deleting these files.

As you might have observed, you can combine different Linux commands with variables, conditional expressions, loops and functions to create your scripts.

At this point, I highly encourage you to proceed in learning advanced Linux where you will learn about more sophisticated and more powerful awk and sed utilities. These two are especially handy when dealing with data.

Here is a quick recap of what we covered in case you need a refresher on a certain step:

1. You now have an understanding of what Linux is.

2. You now know how Linux compares to other operating systems.

3. You are now familiar with the different Linux distributions and how they differ from each other.

4. You learnt how to prepare for a Linux installation and now have an idea how Linux is installed.

5. You now know the different Linux desktops and their corresponding look and feel.

6. You now have an insight on how a Linux filesystem looks like.

7. You can now navigate in a Linux filesystem.

8. You learnt the basic administration tasks in Linux.

9. You can now create users and restrict access in Linux as part of securing your system.

10. You now have an idea of how scripting works in Linux.

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