case Statements

Pattern matching

case compares a string against patterns. Each arm ends with ;;.

case "$1" in
  start) echo "starting" ;;
  stop)  echo "stopping" ;;
  *)     echo "usage: $0 start|stop" >&2; exit 2 ;;
esac

Multiple patterns

Separate alternatives with |.

case "$ext" in
  jpg|jpeg|png) echo "image" ;;
  md|txt)       echo "text" ;;
esac

Glob-style patterns

* and ? work in case patterns. Quote variables you expand as the word being matched.

Good for CLIs

Subcommands and option dispatch stay readable with case.