New file.

test/hello.sh

+#!/bin/sh
+echo hello, world
+exit 0

test/tool.sh

+#!/bin/sh
+n=-n
+e=
+while :
+do
+  echo $n "prompt: $e"
+  read cmd args
+  if test "$cmd" = echo
+  then
+      echo You wrote: $args
+  elif test "$cmd" = stderr
+  then
+      echo You wrote: $args >&2
+  elif test "$cmd" = bye
+  then
+      echo Exiting
+      exit 0
+  else
+      echo unknown command: $cmd
+      exit 1
+  fi
+done