Bash Scripting

 Bash is a command-line interpreter or Unix Shell and it is widely used in GNU/Linux Operating System.  It is written by Brian Jhan Fox. It is used as a default login shell for most Linux distributions. Scripting is used to automate the execution of the tasks so that humans do not need to perform them individually. Bash scripting is a great way to automate different types of tasks in a system. Developers can avoid doing repetitive tasks using bash scripting. 

Bash scripting supports variables, conditional statements, and loops just like programming languages. Below are some of the applications of Bash Scripts – 

Applications of Bash Scripts:

• Manipulating files
• Executing routine tasks like Backup operation
• Automation

The advantages of using Bash Scripts are given below –

Advantages of Bash Scripts:

• It is simple.
• It helps to avoid doing repetitive tasks
• Easy to use
• Frequently performed tasks can be automated
• A sequence of commands can be run as a single command.

The disadvantages of the Bash Scripts are given below – 

Disadvantages of Bash Scripts:

• Any mistake while writing can be costly.
• A new process launched for almost every shell command executed
• Slow execution speed 
• Compatibility problems between different platforms

How to Write Bash Scripts?

To write a Bash Script we will follow the steps –

• First, we will create a file with the .sh extension.
• Next, we will write down the bash scripts within it
• After that, we will provide execution permission to it.

To create and write a file with the .sh extension we can use gedit text editor. The command for it will be –

gedit scriptname.sh

The first line of our script file will be –

#!/bin/bash

This will tell, the system to use Bash for execution. Then we can write our own scripts.

Let’s write down just a simple script that will print some lines in the terminal. The code for it will be –

#!/bin/bash         

echo "Hello, GeeksforGeeks"

Now we will save the file and provide the execution permission to it. To do so use the following command –

chmod +x scriptname.sh

Next to execute the following script we will use the following command –

./scriptname.sh

Here is the terminal shell pictorial depiction after executing the above commands as follows:  

 

Here the script file name is gfg.sh.

Now we can also write more complicated commands using Bash Scripts. Here is an example below in which we are using a condition statement –

Example Script:

#!/bin/bash         
Age=17
if [ "$Age" -ge 18 ]; then
    echo "You can vote"
else
    echo "You cannot vote"    
fi

Output:

You cannot vote

Here is the terminal shell pictorial depiction after executing the above script as follows:  

 

In the above way, we can execute multiple Bash commands all at once.

Now Let’s look into the other important concepts here :

Some Concepts

Decision Making

String and Numeric Comparison

Define Bash Variables and Types

Tutorials