Interview › Scripting (Bash, Groovy)
How do you write a while loop and an until loop? [Basic]
Answer
A while loop runs while a condition succeeds; an until loop runs until a condition succeeds. while is more common, and until is useful for waiting for a desired state.
Technical explanation
Both loops evaluate command exit status, not boolean keywords in the abstract.
Use sleep in polling loops to avoid busy-waiting.
Add timeout or retry limits in production scripts so loops cannot hang forever.
Hands-on example
count=1
while (( count <= 3 )); do
echo "count=$count"
((count++))
done
until curl -fsS http://localhost:8080/health >/dev/null; do
echo "waiting for service"
sleep 2
done
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