diff --git a/src/cmake/check_failure.sh b/src/cmake/check_failure.sh
new file mode 100755
index 000000000..4870fba4a
--- /dev/null
+++ b/src/cmake/check_failure.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+# Auxiliary script that succeeds iff if the execution of input
+# arguments fail.
+if $*; then
+   echo "unexpected success"
+   exit 1
+fi
diff --git a/src/cmake/redirect.sh b/src/cmake/redirect.sh
new file mode 100755
index 000000000..1f61db999
--- /dev/null
+++ b/src/cmake/redirect.sh
@@ -0,0 +1,11 @@
+#!/bin/bash
+# Auxiliary script for redirecting input
+#   Given the arguments $1 ... $n-1 $n,
+#   it executes the command
+#        $1 ... $n-1 < $n
+# This is a hack to workaround a ctest limitation
+length=$(($#-1))
+array=${@:1:$length}
+shift `expr $# - 1`
+last=`echo $1`
+$array < $last
diff --git a/src/shell/CMakeLists.txt b/src/shell/CMakeLists.txt
index 033bba4d7..cb19253bd 100644
--- a/src/shell/CMakeLists.txt
+++ b/src/shell/CMakeLists.txt
@@ -4,7 +4,21 @@ add_executable(lean lean.cpp)
 add_dependencies(lean githash)
 target_link_libraries(lean ${EXTRA_LIBS})
 
-add_test(example1_stdin ${CMAKE_CURRENT_BINARY_DIR}/lean < "${LEAN_SOURCE_DIR}/../examples/lean/ex1.lean")
+add_test(example1_stdin1 ${LEAN_SOURCE_DIR}/cmake/redirect.sh ${CMAKE_CURRENT_BINARY_DIR}/lean "${LEAN_SOURCE_DIR}/../tests/lean/single.lean")
+add_test(example1_stdin2 ${LEAN_SOURCE_DIR}/cmake/redirect.sh ${CMAKE_CURRENT_BINARY_DIR}/lean "-l" "${LEAN_SOURCE_DIR}/../tests/lean/single.lean")
+add_test(example1_stdin3 ${LEAN_SOURCE_DIR}/cmake/redirect.sh ${CMAKE_CURRENT_BINARY_DIR}/lean "--lean" "${LEAN_SOURCE_DIR}/../tests/lean/single.lean")
+add_test(lean_help1 ${CMAKE_CURRENT_BINARY_DIR}/lean --help)
+add_test(lean_help2 ${CMAKE_CURRENT_BINARY_DIR}/lean --h)
+add_test(lean_version1 ${CMAKE_CURRENT_BINARY_DIR}/lean --version)
+add_test(lean_version2 ${CMAKE_CURRENT_BINARY_DIR}/lean --v)
+add_test(lean_ghash1 ${CMAKE_CURRENT_BINARY_DIR}/lean -g)
+add_test(lean_ghash2 ${CMAKE_CURRENT_BINARY_DIR}/lean --githash)
+add_test(lean_luahook1 ${CMAKE_CURRENT_BINARY_DIR}/lean --luahook=100 "${LEAN_SOURCE_DIR}/../tests/lua/big.lua")
+add_test(lean_luahook2 ${CMAKE_CURRENT_BINARY_DIR}/lean -c 100 "${LEAN_SOURCE_DIR}/../tests/lua/big.lua")
+add_test(lean_lua1 ${LEAN_SOURCE_DIR}/cmake/redirect.sh "${CMAKE_CURRENT_BINARY_DIR}/lean" "--lua" "${LEAN_SOURCE_DIR}/../tests/lua/single.lua")
+add_test(lean_lua2 ${LEAN_SOURCE_DIR}/cmake/redirect.sh "${CMAKE_CURRENT_BINARY_DIR}/lean" "-u" "${LEAN_SOURCE_DIR}/../tests/lua/single.lua")
+add_test(lean_unknown_option ${LEAN_SOURCE_DIR}/cmake/check_failure.sh "${CMAKE_CURRENT_BINARY_DIR}/lean" "-z")
+
 
 # LEAN EXAMPLES
 file(GLOB LEANEXAMPLES "${LEAN_SOURCE_DIR}/../examples/lean/*.lean")
diff --git a/src/shell/lean.cpp b/src/shell/lean.cpp
index 3df97c021..d11ba4ba7 100644
--- a/src/shell/lean.cpp
+++ b/src/shell/lean.cpp
@@ -15,9 +15,12 @@ Author: Leonardo de Moura
 #include "util/interrupt.h"
 #include "util/script_state.h"
 #include "kernel/printer.h"
+#include "library/io_state.h"
+#include "library/kernel_bindings.h"
 #include "frontends/lean/parser.h"
 #include "frontends/lean/frontend.h"
 #include "frontends/lua/register_modules.h"
+#include "shell/lua_repl.h"
 #include "version.h"
 #include "githash.h" // NOLINT
 
@@ -83,7 +86,7 @@ int main(int argc, char ** argv) {
     lean::register_modules();
     input_kind default_k = input_kind::Lean; // default
     while (true) {
-        int c = getopt_long(argc, argv, "gvhc:012", g_long_options, &optind);
+        int c = getopt_long(argc, argv, "lugvhc:012", g_long_options, &optind);
         if (c == -1)
             break; // end of command line
         switch (c) {
@@ -111,19 +114,27 @@ int main(int argc, char ** argv) {
             return 1;
         }
     }
-    frontend f;
-    script_state S;
     if (optind >= argc) {
         display_header(std::cout);
-        #if defined(LEAN_WINDOWS)
-        std::cout << "Type 'Exit.' to exit or 'Help.' for help."<< std::endl;
-        #else
-        std::cout << "Type Ctrl-D or 'Exit.' to exit or 'Help.' for help."<< std::endl;
-        #endif
-        shell sh(f, &S);
         signal(SIGINT, on_ctrl_c);
-        return sh();
+        if (default_k == input_kind::Lean) {
+            #if defined(LEAN_WINDOWS)
+            std::cout << "Type 'Exit.' to exit or 'Help.' for help."<< std::endl;
+            #else
+            std::cout << "Type Ctrl-D or 'Exit.' to exit or 'Help.' for help."<< std::endl;
+            #endif
+            frontend f;
+            script_state S;
+            shell sh(f, &S);
+            return sh() ? 0 : 1;
+        } else {
+            lean_assert(default_k == input_kind::Lua);
+            script_state S;
+            S.dostring(g_lua_repl);
+        }
     } else {
+        frontend f;
+        script_state S;
         bool ok = true;
         for (int i = optind; i < argc; i++) {
             char const * ext = get_file_extension(argv[i]);
diff --git a/src/shell/lua_repl.h b/src/shell/lua_repl.h
new file mode 100644
index 000000000..bae05c749
--- /dev/null
+++ b/src/shell/lua_repl.h
@@ -0,0 +1,41 @@
+/*
+Copyright (c) 2013 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+// Very simple read-eval-print for Lua
+static char const * g_lua_repl =
+    "local function trim(s)\n"
+    "   return s:gsub('^%s+', ''):gsub('%s+$', '')\n"
+    "end\n"
+    "local function show_results(...)\n"
+    "   if select('#', ...) > 1 then\n"
+    "      print(select(2, ...))\n"
+    "   end\n"
+    "end\n"
+    "print([[Type 'Exit' to exit.]])\n"
+    "repeat\n"
+    "    io.write'lean > '\n"
+    "    local s = io.read()\n"
+    "    if s == nil then print(""); break end\n"
+    "    if trim(s) == 'Exit' then break end\n"
+    "    local f, err = load(s, 'stdin')\n"
+    "    if err then\n"
+    "        f = load('return (' .. s .. ')', 'stdin')\n"
+    "    end\n"
+    "    if f then\n"
+    "        local ok, err = pcall(f)\n"
+    "        if not ok then\n"
+    "           if is_exception(err) then\n"
+    "               print(err:what())\n"
+    "           else\n"
+    "               print(err)\n"
+    "           end\n"
+    "        else\n"
+    "           if err then print(err) end\n"
+    "        end\n"
+    "    else\n"
+    "        print(err)\n"
+    "    end\n"
+    "until false\n";
diff --git a/tests/lean/single.lean b/tests/lean/single.lean
new file mode 100644
index 000000000..99b96f480
--- /dev/null
+++ b/tests/lean/single.lean
@@ -0,0 +1,6 @@
+Variables a b c : Int.
+Show a + b + c.
+Check a + b.
+Exit.
+(* the following line should be executed *)
+Check a + true.
diff --git a/tests/lean/single.lean.expected.out b/tests/lean/single.lean.expected.out
new file mode 100644
index 000000000..4839be9f7
--- /dev/null
+++ b/tests/lean/single.lean.expected.out
@@ -0,0 +1,7 @@
+  Set: pp::colors
+  Set: pp::unicode
+  Assumed: a
+  Assumed: b
+  Assumed: c
+a + b + c
+a + b : ℤ
diff --git a/tests/lua/single.lua b/tests/lua/single.lua
new file mode 100644
index 000000000..7f687f55d
--- /dev/null
+++ b/tests/lua/single.lua
@@ -0,0 +1,4 @@
+print("hello world")
+local env = environment()
+parse_lean_cmds([[ Variables a b : Int ]], env)
+print(parse_lean([[a + b + 10]], env))