Exit codes ($?) in Bash Scripting - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the special variable $? represent in bash scripting?

$? holds the exit code of the last command run. It tells if the command succeeded (0) or failed (non-zero).

beginner

What exit code usually means success in bash scripts?

An exit code of 0 means the command succeeded without errors.

beginner

How can you check the exit code of a command immediately after running it?

Right after running a command, type echo $? to see its exit code.

intermediate

Why is it important to check exit codes in scripts?

Checking exit codes helps scripts know if a command worked or failed, so they can act accordingly.

beginner

What does a non-zero exit code indicate?

A non-zero exit code means the command failed or had an error.

What does echo $? show in bash?

A Exit code of the last command

B The last command's output

C The current directory

D The process ID

$? stores the exit code of the last command run.

Which exit code means success?

A 0

B Any non-zero number

C 255

D 1

Exit code 0 means the command succeeded.

If a command fails, what is the usual exit code?

A 0

B 1 or other non-zero

C 100

D No exit code

Non-zero exit codes indicate failure or errors.

When should you check $? in a script?

A At the end of the script only

B Before running any command

C Right after running a command

D Only if the script crashes

You check $? immediately after a command to know its result.

What is a common use of exit codes in scripts?

A To open a new terminal window

B To change file permissions

C To print text on screen

D To decide next steps based on success or failure

Scripts use exit codes to decide what to do next.

Explain what $? means and how you use it in a bash script.

Think about how you know if a command worked or not.

Describe why checking exit codes is important when writing bash scripts.

Imagine your script needs to stop or try something else if a command fails.