Question

A systems administrator is writing a Bash maintenance script that accepts a single argument ($1) representing an action: 'start', 'stop', or 'restart'. Any other value should print an error and exit with status 1. The administrator wants the cleanest, most readable construct that matches the argument against these fixed string patterns. Which snippet correctly implements this behavior?

Accepted Answer

case "$1" in
  start) echo "starting" ;;
  stop) echo "stopping" ;;
  restart) echo "restarting" ;;
  *) echo "invalid"; exit 1 ;;
esac

Answer

case $1 in
  start) echo "starting"
  stop) echo "stopping"
  restart) echo "restarting"
  *) echo "invalid"; exit 1
done

Answer

switch ("$1") {
  case start: echo "starting"; break;
  case stop: echo "stopping"; break;
  default: echo "invalid"; exit 1;
}

Answer

if [ "$1" = start | stop | restart ]; then
  echo "$1"
else
  echo "invalid"; exit 1
fi