First Bash script in Bash Scripting - Step-by-Step Execution

Concept Flow - First Bash script

Write script file

↓

Make script executable

↓

Run script in terminal

↓

See output printed

↓

Script ends

This flow shows how you write a bash script, make it runnable, execute it, and see the output.

Execution Sample

Bash Scripting

#!/bin/bash

echo "Hello, world!"

This script prints the text 'Hello, world!' to the terminal.

Execution Table

Step	Action	Command/Code	Output
1	Write script file	#!/bin/bash echo "Hello, world!"
2	Make script executable	chmod +x script.sh
3	Run script	./script.sh	Hello, world!
4	Script ends	Script finishes running

💡 Script finishes after printing the message.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
script file	none	created with code	executable permission set	executed and output shown	exists on disk

Key Moments - 3 Insights

Why do we need to add #!/bin/bash at the top?

The #!/bin/bash line tells the system to use the bash program to run the script, as shown in execution_table step 1.

What does chmod +x do?

chmod +x makes the script file executable, so the system allows running it, as seen in execution_table step 2.

Why do we run the script with ./script.sh?

Using ./ tells the system to run the script from the current folder, which is necessary unless the script is in a system path, as in execution_table step 3.

Visual Quiz - 3 Questions

Look at the execution table, what is printed when the script runs?

A Hello, world!

B Script finished

C Error message

D No output

💡 Hint

Check the Output column at Step 3 in the execution_table.

At which step do we make the script file executable?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the Action column in execution_table for 'Make script executable'.

If we forget to add #!/bin/bash, what might happen when running the script?

A The script runs normally

B The script deletes itself

C The system may not know how to run it

D The script outputs 'Hello, world!' twice

💡 Hint

Refer to key_moments about the purpose of #!/bin/bash.

Concept Snapshot

#!/bin/bash at top tells system to use bash
Write commands in script file (e.g., echo)
Make script executable with chmod +x
Run script with ./scriptname
Script prints output and ends

Full Transcript

This lesson shows how to create your first bash script. First, you write a file with the line #!/bin/bash at the top. This line tells the computer to use bash to run the script. Then you add commands like echo "Hello, world!" to print text. Next, you make the file executable using chmod +x. Finally, you run the script by typing ./script.sh in the terminal. The script runs and prints the message. This simple flow helps you start automating tasks with bash scripts.