How to Write a Shell Script Using Bash Shell in Ubuntu

Last Updated: June 1, 2022 Tested

Have you ever wanted to automate operations in your operating system? Have you ever wanted to write a program that could create a file and copy that file to a specific directory? Have you ever thought about doing these tasks using the BASH Shell in Ubuntu? If so, then this is the article for you!

1

Open a Terminal window.

Launch the Terminal. You can launch the terminal by opening the dash and searching for it by name. You could also open it using the keyboard shortcut Ctrl+Alt+T.

2

Create a file with your text editor.

Launch the vi or vim editor and create a new script. Vim is a free and popular text editor that uses the command line interface. To create a script called ListDir.sh:
- Type vim ListDir.sh and hit ↵ Enter.
- Once inside the Editor, type "I" or "i." This will allow you to insert/start typing your shell script.

3

Begin your script.

Type the following code: #!/bin/bash. This is known as a Shebang line.

4

Type the code.

Type the code as shown in the figure. The first line (echo "Welcome") prints the line "Welcome" into the terminal. echo is used to return the given text and a new line. The second line (ls) lists the contents of the directory. ls is short for list. The final line (another echo statement) returns the text This completes the list of directories.

5

Save and exit your editor.

Exit vim. Type Esc, then :, and then + wq to save and quit. This will write the changes to the file and bring you back to the terminal. Save the file as ListDir.sh

6

Make the script executable.

Change the permissions. Enter the following command: chmod +x ListDir.sh. chmod is a command used in Unix like operating systems to change the access permissions to a file.

7

Run your shell script.

Run the script from the command line. Type ./ListDir.sh to run this script. You should get the list of directories and the message as shown in the above image.

Community Q&A

Question

After typing in "sudo apt install", "(sudo) password for jenneta" appears. What do I do?

Living Concrete

Top Answerer

It is prompting you for the password to your account. Type in your password and then press Enter.
Question

How do I learn shell scripting?

Aryaa Vashisth

Community Answer

Install Python shell scripting and watch tutorials of how to script on Python.
Question

How? I would like to stop the "file already exists" function at the OS level and instead rename the file on the disk before writing whatever to the original file name specified.

Nithik Ramesh

Community Answer

You may have a file of the exact same name and that is why it shows up. Try using another name for your shell script "vim " Or if you want to rename an existing file, do "mv " without the quotes and the angular brackets.

Warnings

For starters, place your shell scripts in your home directory as you begin your shell script journey. Once comfortable, place them in your required directory system.

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Ensure that the files you create, do not reside in any system directories of the / = root file system.

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