Format of flow control functions

"if-then"               if _expr_ then
                            _cmd(s)_
                        elif _expr_
                            _cmd(s)_
                        else
                            _cmd(s)_
                        fi

"case"                  case _word_ in
                            _pattern1_)   _cmd(s)_
                            _pattern2_)   _cmd(s)_
                            *)            break ;;
                        esac

"while"                 while _expr_ do
                            _cmd(s)_
                        done

"for"                   for _variable_ in _list_
                            _cmd(s)_
                        done

"until"                 until _expr_
                        do
                            _cmd(s)_
                        done