Add a "pub global run" command.

sdk/lib/_internal/pub/lib/src/command/global_run.dart

Index: sdk/lib/_internal/pub/lib/src/command/global_run.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command/global_run.dart b/sdk/lib/_internal/pub/lib/src/command/global_run.dart
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index 0000000000000000000000000000000000000000..bdffb93990544c3f812d8c2ca974f5448c108b8f
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+++ b/sdk/lib/_internal/pub/lib/src/command/global_run.dart
@@ -0,0 +1,49 @@
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library pub.command.global_run;
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:barback/barback.dart';
+import 'package:path/path.dart' as path;
+import 'package:stack_trace/stack_trace.dart';
+
+import '../barback/asset_environment.dart';
+import '../command.dart';
+import '../entrypoint.dart';
+import '../executable.dart';
+import '../exit_codes.dart' as exit_codes;
+import '../io.dart';
+import '../log.dart' as log;
+import '../utils.dart';
+
+/// Handles the `global run` pub command.
+class GlobalRunCommand extends PubCommand {
+  bool get requiresEntrypoint => false;
+  bool get takesArguments => true;
+  bool get allowTrailingOptions => false;
+  String get description =>
+      "Run an executable from a globally activated package.";
+  String get usage => "pub global run <package> <executable> [args...]";
+
+  Future onRun() {
+    if (commandOptions.rest.isEmpty) {

[nweiz, 2014/07/02 00:12:02]

I had assumed that "pub global run" would use the same global executable names
that would be added to PATH.

[Bob Nystrom, 2014/07/02 18:00:52]

I wanted something simpler and more explicit for this. Since the stuff on your
PATH is in a different namespace (i.e. set of other named things the user may be
referring to) than the things you can pass to "pub global run", I think it makes
sense to have different strategies there.

We can discuss this more if you'd like.

[nweiz, 2014/07/02 19:57:50]

I think this behavior is fine, it just took me by surprise a bit.

+      usageError("Must specify a package and executable to run.");
+    }
+
+    if (commandOptions.rest.length == 1) {
+      usageError("Must specify an executable to run.");
+    }
+
+    var package = commandOptions.rest[0];
+    var executable = commandOptions.rest[1];
+    var args = commandOptions.rest.skip(2);
+
+    return globals.find(package).then((entrypoint) {
+      return runExecutable(entrypoint, package, executable, args);
+    }).then(flushThenExit);
+  }
+}