Crucial Exams

CompTIA Linux+ XK0-006 (V8) Practice Question

A junior administrator created the following health-check script:

#!/usr/bin/env bash
while nc -z localhost 443; do   # line 2
  echo "Waiting for HTTPS service…"
  sleep 10
done
echo "Service is ready."

The intention is to keep retrying every 10 seconds while the port is closed and exit the loop as soon as the port becomes reachable. In practice, the script does the opposite-it loops when the service is already up and stops when the service is down.

Without replacing the while keyword with until, which single change on line 2 correctly fulfills the requirement?

  • until nc -z localhost 443; do

  • while nc -z localhost 443 || sleep 10; do

  • while ! nc -z localhost 443; do

  • while nc -z localhost 443 >/dev/null 2>&1; [ $? -ne 0 ]; do
CompTIA Linux+ XK0-006 (V8)
Automation, Orchestration, and Scripting
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