HADOOP-15914. hadoop jar command has no help argument. Contributed by Adam Antal.

Signed-off-by: Wei-Chiu Chuang <weichiu@apache.org>
(cherry picked from commit 9f47a2e4a9845b84cc963708c7924b92df2964f6)

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

@@ -139,6 +139,10 @@ function hadoopcmd_case
       if [[ -n "${YARN_OPTS}" ]] || [[ -n "${YARN_CLIENT_OPTS}" ]]; then
         hadoop_error "WARNING: Use \"yarn jar\" to launch YARN applications."
       fi
+      if [[ -z $1 || $1 = "--help" ]]; then
+        echo "Usage: hadoop jar <jar> [mainClass] args..."
+        exit 0
+      fi
       HADOOP_CLASSNAME=org.apache.hadoop.util.RunJar
     ;;
     jnipath)

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

@@ -189,6 +189,11 @@ call :updatepath %HADOOP_BIN_PATH%
   ) else if defined YARN_CLIENT_OPTS (
     @echo WARNING: Use "yarn jar" to launch YARN applications.
   )
+  @rem if --help option is used, no need to call command
+  if [!hadoop-command-arguments[%1%]!]==["--help"] (
+    @echo Usage: hadoop jar <jar> [mainClass] args...
+    goto :eof
+  )
   set CLASS=org.apache.hadoop.util.RunJar
   goto :eof