When would `case` be better than `if-elif-else`?

That is an excellent question! While if-elif-else and case can often achieve the same result, case is generally considered better in the following scenarios:

1. Readability with Multiple Matches

When you are checking a single variable against many possible values (like a menu selection or command-line flags), case is much cleaner and easier to read.

• if-elif-else version:

  if [ "$choice" == "1" ]; then
      add
  elif [ "$choice" == "2" ]; then
      subtract
  elif [ "$choice" == "3" ]; then
      multiply
  else
      echo "Invalid"
  fi

• case version:

  case $choice in
      1) add ;;
      2) subtract ;;
      3) multiply ;;
      *) echo "Invalid" ;;
  esac

2. Pattern Matching (Wildcards)

case supports glob patterns (like *, ?, and []), making it very powerful for matching strings without using complex regular expressions.

case $filename in
    *.txt) echo "This is a text file" ;;
    *.jpg|*.png) echo "This is an image" ;;
    [0-9]*) echo "This file starts with a number" ;;
    *) echo "Unknown format" ;;
esac

3. Handling Multiple Conditions for one Action

In a case statement, you can use the pipe symbol | to mean "OR". This allows multiple patterns to trigger the same block of code without repeating your logic.

case $answer in
    [yY]|[yY][eE][sS])
        echo "You agreed!"
        ;;
    [nN]*)
        echo "You declined."
        ;;
esac

Summary: Use case when...

• You are evaluating one specific variable.
• You have many constant values to check against.
• You want to use simple pattern matching (like checking file extensions).
• You want to group multiple values together to trigger the same action.

Use if, however, when you need to compare different variables or perform complex math logic (like if [ $a -gt $b ] && [ $c -lt $d ]).