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

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

@@ -178,6 +178,9 @@ Release 2.7.0 - UNRELEASED
     HADOOP-11463 Replace method-local TransferManager object with
     S3AFileSystem#transfers. (Ted Yu via stevel)
 
+    HADOOP-11543. Improve help message for hadoop/yarn command.
+    (Brahma Reddy Battula via ozawa)
+
   OPTIMIZATIONS
 
     HADOOP-11323. WritableComparator#compare keeps reference to byte array.

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

@@ -32,8 +32,10 @@ HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-$DEFAULT_LIBEXEC_DIR}
 . $HADOOP_LIBEXEC_DIR/hadoop-config.sh
 
 function print_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 "  fs                   run a generic filesystem user client"
   echo "  version              print the version"
   echo "  jar <jar>            run a jar file"
@@ -47,8 +49,6 @@ function print_usage(){
   echo "                       Hadoop jar and the required libraries"
   echo "  daemonlog            get/set the log level for each daemon"
   echo "  trace                view and modify Hadoop tracing settings"
-  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

@@ -65,8 +65,10 @@ HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-$DEFAULT_LIBEXEC_DIR}
 . $HADOOP_LIBEXEC_DIR/yarn-config.sh
 
 function print_usage(){
-  echo "Usage: yarn [--config confdir] [--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 "  resourcemanager -format-state-store   deletes the RMStateStore"
   echo "  resourcemanager                       run the ResourceManager"
   echo "  nodemanager                           run a nodemanager on each slave"
@@ -89,8 +91,7 @@ function print_usage(){
   echo "                                        required libraries"
   echo "  daemonlog                             get/set the log level for each"
   echo "                                        daemon"
-  echo " or"
-  echo "  CLASSNAME                             run the class named CLASSNAME"
+  echo ""
   echo "Most commands print help when invoked w/o parameters."
 }