Use more semantic exit codes so we can detect HTTP errors.

utils/pub/pub.dart

Index: utils/pub/pub.dart
diff --git a/utils/pub/pub.dart b/utils/pub/pub.dart
index 1bd1a40e543f8c3239dc786368cd08bd603f5eac..92cc62af4bf7129a68ddf40b2d314670c6b7241a 100644
--- a/utils/pub/pub.dart
+++ b/utils/pub/pub.dart
@@ -17,6 +17,7 @@
 #import('command_update.dart');
 #import('command_version.dart');
 #import('entrypoint.dart');
+#import('exit_codes.dart', prefix: 'exit_codes');
 #import('git_source.dart');
 #import('hosted_source.dart');
 #import('package.dart');
@@ -96,7 +97,7 @@ main() {
   if (command == null) {
     printError('Unknown command "${globalOptions.rest[0]}".');
     printError('Run "pub help" to see available commands.');
-    exit(64); // See http://www.freebsd.org/cgi/man.cgi?query=sysexits.
+    exit(exit_codes.USAGE);
     return;
   }
 
@@ -176,7 +177,7 @@ class PubCommand {
      commandOptions = commandParser.parse(commandArgs);
     } on FormatException catch (e) {
       this.printUsage(description: e.message);
-      return;
+      exit(exit_codes.USAGE);
     }
 
     handleError(error, trace) {
@@ -195,9 +196,7 @@ class PubCommand {
         printError(trace);
       }
 
-      // TODO(nweiz): Use the more semantic error codes in
-      // http://www.freebsd.org/cgi/man.cgi?query=sysexits
-      exit(1);
+      exit(_exitCode(error));
     }
 
     var future = new Future.immediate(null);
@@ -258,4 +257,17 @@ class PubCommand {
       print(commandUsage);
     }
   }
+
+  /// Returns the appropriate exit code for [exception], falling back on 1 if no
+  /// appropriate exit code could be found.
+  int _exitCode(exception) {

[Bob Nystrom, 2012/09/19 18:27:42]

How about a nice verby name like _chooseExitCode?

[nweiz, 2012/09/19 18:33:56]

Done.

+    if (exception is HttpException || exception is HttpParserException ||
+        exception is SocketIOException || exception is PubHttpException) {
+      return exit_codes.UNAVAILABLE;
+    } else if (exception is FormatException) {
+      return exit_codes.DATA;
+    } else {
+      return 1;
+    }
+  }
 }