Waiting for output streams to have finished before exiting grunt.

lib/grunt.js

@@ -132,7 +132,8 @@ grunt.tasks = function(tasks, options, done) {
         done();
       } else {
         // Otherwise, explicitly exit.
-        process.exit(0);
+        var exitProcess = require('./util/exit');
+        exitProcess(0);
       }
     }
   });

lib/grunt/fail.js

@@ -11,6 +11,7 @@ var grunt = require('../grunt');
 
 // The module to be exported.
 var fail = module.exports = {};
+var exitProcess = require('../util/exit');
 
 // Error codes
 // 1. Generic error.
@@ -36,10 +37,10 @@ function writeln(e, mode) {
   grunt.log.writeln([tags[mode][0], msg.yellow, tags[mode][1]].join(' '));
 }
 
-// A fatal error occured. Abort immediately.
+// A fatal error occured. Abort immediately (as soon as stdout and stderr have received all their data).
 fail.fatal = function(e, errcode) {
   writeln(e, 'fatal');
-  process.exit(typeof errcode === 'number' ? errcode : 1);
+  exitProcess(typeof errcode === 'number' ? errcode : 1);
 };
 
 // Keep track of error and warning counts.
@@ -70,7 +71,7 @@ fail.warn = function(e, errcode) {
       }
       // Log and exit.
       grunt.log.writeln().fail('Aborted due to warnings.');
-      process.exit(typeof errcode === 'number' ? errcode : 2);
+      exitProcess(typeof errcode === 'number' ? errcode : 2);
     }
   }
 };

lib/grunt/help.js

@@ -65,5 +65,5 @@ grunt.log.writeln().writelns(
   '\n\n' +
   'For more information, see http://gruntjs.com/'
 );
-
-process.exit();
+var exitProcess = require('../util/exit');
+exitProcess();

lib/util/exit.js

@@ -0,0 +1,25 @@
+// Waits for the stream to have fully received its content.
+var waitForStreamEnd = function (stream, callback) {
+    // Writes an empty string to check the state of the buffer:
+    if (!stream.write("")) {
+        stream.once('drain', callback);
+    } else {
+        callback();
+    }
+};
+
+// Exits the process asynchronously, making sure the stdout and stderr streams have fully received their content.
+var exitProcess = function (exitCode) {
+    var ok = 0;
+    var increaseOk = function () {
+        ok++;
+        if (ok == 3) {
+            process.exit(exitCode);
+        }
+    };
+    waitForStreamEnd(process.stdout, increaseOk);
+    waitForStreamEnd(process.stderr, increaseOk);
+    process.nextTick(increaseOk);
+};
+
+module.exports = exitProcess;