[Solved] In bash, what happens when you use the expression ${input:-default_value} inside a script? - Ans: It returns input if set and non-empty; otherwise, it returns default_value... | Bash Scripting

Bash Scripting - User Input

In bash, what happens when you use the expression ${input:-default_value} inside a script?

A

It returns <code>input</code> if set and non-empty; otherwise, it returns <code>default_value</code> without changing <code>input</code>.

BIt assigns <code>default_value</code> to <code>input</code> if <code>input</code> is unset or empty.

CIt always assigns <code>default_value</code> to <code>input</code> regardless of its current value.

DIt throws an error if <code>input</code> is unset.

Step-by-Step Solution

Solution:

Step 1: Understand the syntax
The expression ${var:-default} returns the value of var if it is set and non-empty.
Step 2: Behavior when var is unset or empty
If var is unset or empty, it returns default but does NOT assign it to var.
Final Answer:
It returns input if set and non-empty; otherwise, it returns default_value without changing input. -> Option A
Quick Check:
Test with unset input and echo ${input:-default_value} [OK]

Quick Trick: :- returns default without assignment [OK]

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In bash, what happens when you use the expression ${input:-default_value} inside a script?