Custom exit codes (exit N) in Bash Scripting - Step-by-Step Execution

Concept Flow - Custom exit codes (exit N)

Start Script

↓

Run commands

↓

Call exit N

↓

Script stops

↓

Return exit code N to OS

The script runs commands, then stops immediately when exit N is called, returning N as the exit code to the operating system.

Execution Sample

Bash Scripting

echo "Hello"
exit 3
echo "Bye"

Prints 'Hello', then exits with code 3, so 'Bye' is never printed.

Execution Table

Step	Command	Action	Output	Exit Code	Next Step
1	echo "Hello"	Print message	Hello	0	Continue
2	exit 3	Exit script with code 3		3	Stop
3	echo "Bye"	Skipped because script exited			No

💡 Script stops at step 2 due to exit 3, so step 3 is not executed.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
Exit Code	N/A	0	3	3

Key Moments - 2 Insights

Why does the script stop after 'exit 3' and not print 'Bye'?

Because 'exit 3' immediately stops the script and returns code 3, so commands after it are not run (see execution_table step 2 and 3).

What does the number after 'exit' mean?

It is the exit code returned to the operating system, showing success (0) or error (non-zero). Here, '3' is a custom code (see variable_tracker).

Visual Quiz - 3 Questions

Look at the execution table, what is the exit code after step 1?

A 0

B 3

C 1

D None

💡 Hint

Check the 'Exit Code' column at step 1 in the execution_table.

At which step does the script stop running commands?

A Step 1

B Step 2

C Step 3

D It never stops

💡 Hint

Look at the 'Next Step' column in execution_table where it says 'Stop'.

If we change 'exit 3' to 'exit 0', what changes in the exit code?

A Exit code becomes 1

B Exit code becomes 3

C Exit code becomes 0

D No exit code

💡 Hint

Refer to variable_tracker and understand exit code meaning.

Concept Snapshot

Use 'exit N' in bash to stop a script and return a custom exit code N.
Exit code 0 means success; non-zero means error or special status.
Commands after 'exit' do not run.
Useful for signaling script result to other programs or scripts.

Full Transcript

This example shows a bash script that prints 'Hello', then uses 'exit 3' to stop immediately with exit code 3. The command after exit is skipped. The exit code is a number returned to the operating system to indicate success or failure. Zero means success, any other number is a custom error or status code. This helps other scripts or programs know what happened. The execution table traces each step, showing output and exit code changes. The variable tracker shows how the exit code changes from start to finish. Key moments clarify why the script stops and what the exit code means. The quiz tests understanding of exit codes and script flow.