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Operator Precedence: What Happens First

Operators have precedence. Some happen before others. Understand it.

Here's the thing: Precedence matters. Use parentheses when unsure. Make it clear.

Arithmetic Precedence​

result=$((2 + 3 * 4))            # 14, not 20
result=$(((2 + 3) * 4))          # 20

My take: Multiplication before addition. Use parentheses to clarify.

Logical Precedence​

if [ "$a" = "1" ] && [ "$b" = "2" ] || [ "$c" = "3" ]; then
    # Ambiguous
fi

if ([ "$a" = "1" ] && [ "$b" = "2" ]) || [ "$c" = "3" ]; then
    # Clear
fi

My take: Use parentheses. Make it clear.

Common Patterns​

Use Parentheses​

result=$(((a + b) * c))

Group Conditions​

if ([ "$x" = "1" ] && [ "$y" = "2" ]) || [ "$z" = "3" ]; then
    echo "Match"
fi

Common Mistakes (I've Made These)​

  1. Not using parentheses: Use them. Make it clear.

  2. Assuming order: Don't assume. Use parentheses.

  3. Complex expressions: Break them down. Simpler is better.

What's Next?​

Now that you understand precedence, you can write clearer expressions. Or review Operators to reinforce.

Personal note: Precedence confused me at first. Then I learned: use parentheses. Now I always use them. It's clearer. Do it.