debugger: error out without script

TODO:

debug> run script.js

lib/_debugger.js

@@ -6,6 +6,11 @@ var spawn = require('child_process').spawn;
 exports.port = 5858;
 
 exports.start = function() {
+  if (process.argv.length < 3) {
+    console.error("Usage: node debug script.js");
+    process.exit(1);
+  }
+
   var interface = new Interface();
   process.on('uncaughtException', function (e) {
     console.error("There was an internal error in Node's debugger. " +

src/node.cc

@@ -1832,12 +1832,10 @@ static void ParseDebugOpt(const char* arg) {
 
 static void PrintHelp() {
   printf("Usage: node [options] script.js [arguments] \n"
+         "       node debug script.js [arguments] \n"
+         "\n"
          "Options:\n"
          "  -v, --version        print node's version\n"
-         "  --debug[=port]       enable remote debugging via given TCP port\n"
-         "                       without stopping the execution\n"
-         "  --debug-brk[=port]   as above, but break in script.js and\n"
-         "                       wait for remote debugger to connect\n"
          "  --v8-options         print v8 command line options\n"
          "  --vars               print various compiled-in variables\n"
          "  --max-stack-size=val set max v8 stack size (bytes)\n"
@@ -1846,13 +1844,11 @@ static void PrintHelp() {
          "NODE_PATH              ':'-separated list of directories\n"
          "                       prefixed to the module search path,\n"
          "                       require.paths.\n"
-         "NODE_DEBUG             Print additional debugging output.\n"
          "NODE_MODULE_CONTEXTS   Set to 1 to load modules in their own\n"
          "                       global contexts.\n"
-         "NODE_DISABLE_COLORS  Set to 1 to disable colors in the REPL\n"
+         "NODE_DISABLE_COLORS    Set to 1 to disable colors in the REPL\n"
          "\n"
-         "Documentation can be found at http://nodejs.org/api.html"
-         " or with 'man node'\n");
+         "Documentation can be found at http://nodejs.org/\n");
 }
 
 // Parse node command line arguments.