Copy restore-TTY functions from Scala script so binary distros don't need 'scala' installed

spark-shell

-#!/bin/sh
+#!/bin/bash --posix
 FWDIR="`dirname $0`"
-export SPARK_LAUNCH_WITH_SCALA=1
-exec $FWDIR/run spark.repl.Main "$@"
+
+# Copy restore-TTY-on-exit functions from Scala script so spark-shell exits properly even in
+# binary distribution of Spark where Scala is not installed
+exit_status=127
+saved_stty=""
+
+# restore stty settings (echo in particular)
+function restoreSttySettings() {
+  stty $saved_stty
+  saved_stty=""
+}
+
+function onExit() {
+  if [[ "$saved_stty" != "" ]]; then
+    restoreSttySettings
+  fi
+  exit $exit_status
+}
+
+# to reenable echo if we are interrupted before completing.
+trap onExit INT
+
+# save terminal settings
+saved_stty=$(stty -g 2>/dev/null)
+# clear on error so we don't later try to restore them
+if [[ ! $? ]]; then
+  saved_stty=""
+fi
+
+$FWDIR/run spark.repl.Main "$@"
+
+# record the exit status lest it be overwritten:
+# then reenable echo and propagate the code.
+exit_status=$?
+onExit