Bash Scripting

A bash shell script is a file that holds a set of bash commands to be read and executed by Bash.

Bash files are commonly denoted with a .sh file extension for example:

Additionally the first line of a Bash script commonly contains a shebang. A shebang is a line that informs the operating system of the exact shell to use when executing the script. The shebang simply points to the absolute path of the shell.

For example: #!/bin/bash.


Any valid bash syntax can be run in a file without the .sh extension and without a shebang when the bash command is invoked. However, to run a file without explicitly invoking the bash command, the bash script file requires a shebang and must be executable.

Once these conditions are met the script can be invoked directly without the bash command.


The following examples are complete bash scripts that can be executed on any machine with the bash package.

Create new directory/new file script

The first example:

  1. navigates to a specific directory
  2. creates a new directory
  3. changes into the new directory
  4. creates a new file

Create a new file called and add the following contents:


## navgiate to /home/student/Desktop
cd /home/student/Desktop

## create new directory inside of /home/student/Desktop
mkdir new-directory

## navigate to  new-directory inside of /Desktop
cd new-directory

## create new file inside of new-directory
touch new-file

Execute the script by invoking the bash package and providing the path to the newly created script as the argument:


Upon creating and executing the script a new directory and file will be created in one fell swoop!

Look at the contents of the /home/student/Desktop and /home/student/Desktop/new-directory directories.

LaunchCode Employee Script

The first script was pretty basic. Let’s create a more complex script that combines multiple tools we’ve learned in this class. Let’s scrape, extract, and transform some data into a more usable state.

The LaunchCode website provides an about page, and on the page is a listing of all current LaunchCode employees.

It looks similar to the following image:

LC about page output

Say we want a script that will:

  1. make a request for the raw HTML
  2. extract the data we want with grep
  3. trim the data using sed
  4. write the output to a new file

The about page of the LaunchCode website is subject to change. To ensure the provided script will work we have provided the raw HTML as a part of this curriculum.

The file the script will be requesting is found at the link of the following attachment.

Practice File

By hovering over the file you can find the URL of this specific resource, in the bottom left corner of your web browser.


You can add that specific resource to the wget command inside of the following script! As I was creating this walkthrough the specific link for me was http://localhost:1313/bash-scripting/walkthrough/script/_index.files/about.html

Create a new file called and add the following code:

cd /home/student/Desktop

mkdir launchcode-roster

cd launchcode-roster


cat about.html | grep '<p style="line-height: 1.4;"><strong>.*</strong><br/>.*<br/>' | sed 's/^.*<strong>//g' | sed 's/<\/strong><br\/>/: /g' | sed 's/<br\/>.*$//g' > lc-employees.txt

cat lc-employees.txt | grep "^John\|Paul" > john-paul.txt

The url you provide for the wget command must be correct in order for this to work properly! Make sure you copy the correct url from the about.html file! The portion of the URL has likely changed!

Execute the newly created script:



bash output

Script Validation

Check to see if the script worked!


  • Navigate to your Desktop folder to view the newly created launchcode-roster directory.
  • cd into the launchcode-roster directory and list the contents.
  • cat out of the contents of the john-paul.txt

Check the contents of the lc-employees.txt file! Inside should be all of the employees of LaunchCode with their titles.


  • Bash scripting description
    • #!/bin/bash: shebang
  • Example Bash Scripts:
    • Script to change directories, create a new directory, add a file to new directory
    • Script to create a list of LaunchCode Employees and also separate John and Paul from the list!