after many years, I learned that usually shell scripts are only good for the most basic of uses. here is a similar program in Go that doesn't require any hacks:

    package main
    import "os"
    
    func main() {
       var x int
       switch len(os.Args) {
       case 1: goto start
       default:
          switch os.Args[1] {
          case "foo": goto foo
          case "mid": goto mid
          }
       }
       start:
       x = 100
       goto foo
    
       mid:
       x = 101
       println("This is not printed!")
    
       foo:
       if x == 0 { x = 10 }
       println("x is", x)
    }