Creating Bash Scripts On Linux – Part 1

Eventually, as you advance with Linux Mint, you’ll want to start creating your own automated tasks and programs. These are essentially scripts, Bash Shell scripts to be exact, and they work in the same way as a DOS Batch file does, or any other programming language.

A Bash script is simply a series of commands that Mint will run through to complete a certain task. They can be simple or remarkably complex, it all depends on the situation.

Step 1

You’ll be working within the Terminal and with a text editor throughout the coming pages. There are alternatives to the text editor, which we’ll look at in a moment but for the sake of ease, we’ll be doing our examples in Xed. Before you begin, however, run through the customary update check: sudo apt-get update && sudo apt-get upgrade.

Step 2

There are several text editors we can use to create a Bash script: Xed, Vi, Nano, Vim, GNU Emacs and so on. In the end it all comes down to personal preference. Our use of Xed is purely due to making it easier to read the script in the screenshots you see below.

Step 3

To begin with, and before you start to write any scripts, you need to create a folder where you can put all our scripts into. Start with mkdir scripts, and enter the folder cd scripts/. This will be our working folder and from here you can create sub-folders if you want of each script you create.

Step 4

Windows users will be aware that in order for a batch file to work, as in be executed and follow the programming within it, it needs to have a .BAT file extension. Linux is an extension-less operating system but the convention is to give scripts a .sh extension.

Step 5

Let’s start with a simple script to output something to the Terminal. Enter xed helloworld.sh. This will launch Xed and create a file called helloworld.sh. In Xed, enter the following: #!/bin/bash, then on a new line: echo Hello World!.

Step 6

The #!/bin/bash line tells the system what Shell you’re going to be using, in this case Bash. The hash (#) denotes a comment line, one that is ignored by the system, the exclamation mark (!) means that the comment is bypassed and will force the script to execute the line as a command. This is also known as a Hash-Bang.

Step 7

You can save this file, clicking File > Save, and exit back to the Terminal. Entering ls, will reveal the script in the folder. To make any script executable, and able to run, you need to modify its permissions. Do this with chmod +x helloworld.sh. You need to do this with every script you create.

Step 8

When you enter ls again, you can see that the helloworld.sh script has now turned from being white to green, meaning that it’s now an executable file. To run the script, in other words make it do the things you’ve typed into it, enter:

./helloworld.sh.

Step 9

Although it’s not terribly exciting, the words ‘Hello World!’ should now be displayed in the Terminal. The echo command is responsible for outputting the words after it in the Terminal, as we move on you can make the echo command output to other sources.

Step 10

Think of echo as the old BASIC Print command. It displays either text, numbers or any variables that are stored in the system, such as the current system date.

Try this example:

 echo Hello World! Today is $(date +%A).

The $(date +%A) is calling the system variable that stores the current day of the week.

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