Index: src/java/org/apache/nutch/crawl/GeneratorJob.java
===================================================================
--- src/java/org/apache/nutch/crawl/GeneratorJob.java	(revision 1453679)
+++ src/java/org/apache/nutch/crawl/GeneratorJob.java	(working copy)
@@ -222,6 +222,12 @@
   }
 
   public int run(String[] args) throws Exception {
+    if (args.length == 0) {
+      System.out.println("Usage: GeneratorJob [-topN N] [-crawlId cid] [-noFilter] [-noNorm]");
+      System.out.println("Infos: All parameters using the default.");
+      System.out.println("Infos: GeneratorJob -topN Long.MAX_VALUE");
+    }
+
     long curTime = System.currentTimeMillis(), topN = Long.MAX_VALUE;
     boolean filter = true, norm = true;