Bash Scripting - Quoting and Expansion
Which of the following correctly uses arithmetic expansion to subtract 7 from 15 in bash?
Which of the following correctly uses arithmetic expansion to subtract 7 from 15 in bash?
easy🧠 Conceptual Q2 of 15
Step-by-Step Solution
Solution:
Step 1: Identify correct arithmetic syntax
Arithmetic expansion requires$(( expression ))syntax.Step 2: Check each option
result=$((15 - 7)) uses correct syntax. result=$(15 - 7) uses command substitution which treats it as a command, not math. result=$[15 - 7] uses deprecated syntax. result=15 - 7 assigns a string, not calculation.Final Answer:
result=$((15 - 7)) -> Option CQuick Check:
Correct syntax = result=$((15 - 7)) [OK]
Quick Trick: Always use $(( )) for math, not $() or plain assignment [OK]
Common Mistakes:
MISTAKES- Confusing $() with $(( ))
- Using deprecated $[] syntax
- Assigning math as string
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