Interview › Scripting (Bash, Groovy)
How do you do arithmetic in Bash? [Basic]
Answer
Bash arithmetic is normally done with $((expression)) for expansion or ((expression)) for evaluation and condition checks. It supports integer arithmetic, increments, comparisons, and common operators.
Technical explanation
Bash arithmetic is integer-based, not floating point; use awk, bc, or Python when decimals are required.
Variables inside arithmetic contexts do not need a leading dollar sign, although using one is often accepted.
(( expression )) returns exit status 0 when the expression is nonzero and 1 when it is zero.
Hands-on example
replicas=2
replicas=$((replicas + 1))
echo "replicas=$replicas"
if (( replicas >= 3 )); then
echo "enough capacity"
fi
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