diff --git a/tracker/rabit_hadoop.py b/tracker/rabit_hadoop.py
index 21e59115f..fbed6ad8f 100755
--- a/tracker/rabit_hadoop.py
+++ b/tracker/rabit_hadoop.py
@@ -17,16 +17,16 @@ hadoop_streaming_jar = None
 # code 
 hadoop_home = os.getenv('HADOOP_HOME')
 if hadoop_home != None:
-  if hadoop_binary == None:
-    hadoop_binary = hadoop_home + '/bin/hadoop'
-    assert os.path.exists(hadoop_binary), "HADDOP_HOME does not contain the hadoop binary"
-  if hadoop_streaming_jar == None:
-    hadoop_streaming_jar = hadoop_home + '/lib/hadoop-streaming.har'
-    assert os.path.exists(hadoop_streaming_jar), "HADDOP_HOME does not contain the haddop streaming jar"
+    if hadoop_binary == None:
+        hadoop_binary = hadoop_home + '/bin/hadoop'
+        assert os.path.exists(hadoop_binary), "HADDOP_HOME does not contain the hadoop binary"
+    if hadoop_streaming_jar == None:
+        hadoop_streaming_jar = hadoop_home + '/lib/hadoop-streaming.har'
+        assert os.path.exists(hadoop_streaming_jar), "HADDOP_HOME does not contain the haddop streaming jar"
 
 if hadoop_binary == None or hadoop_streaming_jar == None:
-  print 'Warning: Cannot auto-detect path to hadoop and streaming jar, need to set them via arguments -hs and -hb'
-  print '\tTo enable auto-detection, you can set enviroment variable HADOOP_HOME or modify rabit_hadoop.py line 14'
+    print 'Warning: Cannot auto-detect path to hadoop and streaming jar, need to set them via arguments -hs and -hb'
+    print '\tTo enable auto-detection, you can set enviroment variable HADOOP_HOME or modify rabit_hadoop.py line 14'
 
 parser = argparse.ArgumentParser(description='Rabit script to submit rabit jobs using Hadoop Streaming')
 parser.add_argument('-n', '--nslaves', required=True, type=int,
@@ -34,45 +34,47 @@ parser.add_argument('-n', '--nslaves', required=True, type=int,
 parser.add_argument('-v', '--verbose', default=0, choices=[0, 1], type=int,
                     help = 'print more messages into the console')
 parser.add_argument('-ac', '--auto_file_cache', default=1, choices=[0, 1], type=int,
-                    help = 'whether automatically cache the files in the command list to hadoop localfile')
+                    help = 'whether automatically cache the files in the command to hadoop localfile, this is on by defaultz')
 parser.add_argument('-i', '--input', required=True,
                     help = 'input path in HDFS')
 parser.add_argument('-o', '--output', required=True,
                     help = 'output path in HDFS')
 parser.add_argument('-f', '--files', nargs = '*',
-                    help = 'the cached file list in mapreduce')
+                    help = 'the cached file list in mapreduce,'\
+                        ' the submission script will automatically cache all the files which appears in command.'\
+                        ' you may need this option to cache additional files, or manually cache files when auto_file_cache is off')
 if hadoop_binary == None:
-  parser.add_argument('-hb', '--hadoop_binary', required = True,
-                      help="path-to-hadoop binary folder")  
+    parser.add_argument('-hb', '--hadoop_binary', required = True,
+                        help="path-to-hadoop binary folder")  
 else:
-  parser.add_argument('-hb', '--hadoop_binary', default = hadoop_binary, 
-                      help="path-to-hadoop binary folder")  
+    parser.add_argument('-hb', '--hadoop_binary', default = hadoop_binary, 
+                        help="path-to-hadoop binary folder")  
 
 if hadoop_streaming_jar == None:
-  parser.add_argument('-jar', '--hadoop_streaming_jar', required = True,
-                      help='path-to hadoop streamimg jar file')
+    parser.add_argument('-jar', '--hadoop_streaming_jar', required = True,
+                        help='path-to hadoop streamimg jar file')
 else:
-  parser.add_argument('-jar', '--hadoop_streaming_jar', default = hadoop_streaming_jar,
-                      help='path-to hadoop streamimg jar file')
+    parser.add_argument('-jar', '--hadoop_streaming_jar', default = hadoop_streaming_jar,
+                        help='path-to hadoop streamimg jar file')
 parser.add_argument('command', nargs='+',
                     help = 'command for rabit program')
 args = parser.parse_args()
 
 def hadoop_streaming(nslaves, slave_args):
-  cmd = '%s jar %s -D mapred.map.tasks=%d' % (args.hadoop_binary, args.hadoop_streaming_jar, nslaves)
-  cmd += ' -input %s -output %s' % (args.input, args.output)
-  cmd += ' -mapper \"%s\" -reducer \"/bin/cat\" ' % (' '.join(args.command + slave_args))
-  fset = set()
-  if args.auto_file_cache:
-    for f in args.command:
-      if os.path.exists(f):
-        fset.add(f)
-  for flst in args.files:
-    for f in flst.split('#'):
-      fset.add(f)
-  for f in fset:
-    cmd += ' -file %s' % f
-  print cmd
-  subprocess.check_call(cmd, shell = True)
+    cmd = '%s jar %s -D mapred.map.tasks=%d' % (args.hadoop_binary, args.hadoop_streaming_jar, nslaves)
+    cmd += ' -input %s -output %s' % (args.input, args.output)
+    cmd += ' -mapper \"%s\" -reducer \"/bin/cat\" ' % (' '.join(args.command + slave_args))
+    fset = set()
+    if args.auto_file_cache:
+        for f in args.command:
+            if os.path.exists(f):
+                fset.add(f)
+    for flst in args.files:
+        for f in flst.split('#'):
+            fset.add(f)
+    for f in fset:
+        cmd += ' -file %s' % f
+    print cmd
+    subprocess.check_call(cmd, shell = True)
 
 tracker.submit(args.nslaves, [], fun_submit = hadoop_streaming, verbose = args.verbose)