HADOOP-11543. Improve help message for hadoop/yarn command. Contributed by Brahma Reddy Battula.

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -852,6 +852,9 @@ Release 2.7.0 - UNRELEASED
     HADOOP-10062. race condition in MetricsSystemImpl#publishMetricsNow that 
     causes incorrect results. (Sangjin Lee via junping_du)
 
+    HADOOP-11543. Improve help message for hadoop/yarn command.
+    (Brahma Reddy Battula via ozawa)
+
 Release 2.6.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/bin/hadoop

@@ -17,8 +17,10 @@
 
 function hadoop_usage()
 {
-  echo "Usage: hadoop [--config confdir] [--loglevel loglevel] COMMAND"
-  echo "       where COMMAND is one of:"
+  echo "Usage: hadoop [--config confdir] [COMMAND | CLASSNAME]"
+  echo "  CLASSNAME            run the class named CLASSNAME"
+  echo " or"
+  echo "  where COMMAND is one of:"
   echo "  archive -archiveName NAME -p <parent path> <src>* <dest>"
   echo "                       create a Hadoop archive"
   echo "  checknative [-a|-h]  check native Hadoop and compression "
@@ -39,8 +41,6 @@ function hadoop_usage()
   echo "  key                  manage keys via the KeyProvider"
   echo "  trace                view and modify Hadoop tracing settings"
   echo "  version              print the version"
-  echo " or"
-  echo "  CLASSNAME            run the class named CLASSNAME"
   echo ""
   echo "Most commands print help when invoked w/o parameters."
 }

hadoop-yarn-project/hadoop-yarn/bin/yarn

@@ -17,9 +17,10 @@
 
 function hadoop_usage
 {
-  echo "Usage: yarn [--config confdir] [--daemon (start|stop|status)]"
-  echo "           [--loglevel loglevel] COMMAND"
-  echo "where COMMAND is one of:"
+  echo "Usage: yarn [--config confdir] [COMMAND | CLASSNAME]"
+  echo "  CLASSNAME                             run the class named CLASSNAME"
+  echo " or"
+  echo "  where COMMAND is one of:"
   echo "  application                           prints application(s) report/kill application"
   echo "  applicationattempt                    prints applicationattempt(s) report"
   echo "  classpath                             prints the class path needed to get the"
@@ -39,8 +40,7 @@ function hadoop_usage
   echo "  sharedcachemanager                    run the SharedCacheManager daemon"
   echo "  timelineserver                        run the timeline server"
   echo "  version                               print the version"
-  echo " or"
-  echo "  CLASSNAME                             run the class named CLASSNAME"
+  echo ""
   echo "Most commands print help when invoked w/o parameters."
 }