MAPREDUCE-2682. Add "mapred classpath" command to print classpath for MR applications. Contributed by vinodkv.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1145889 13f79535-47bb-0310-9956-ffa450edef68

mapreduce/CHANGES.txt

@@ -13,6 +13,9 @@ Trunk (unreleased changes)
 
   NEW FEATURES
 
+    MAPREDUCE-2682. Add "mapred classpath" command to print classpath
+    for MR applications. (vinodkv via acmurthy) 
+
     MAPREDUCE-2107. [Gridmix] Total heap usage emulation in Gridmix.
     (Amar Kamat and Ravi Gummadi via amarrk)
 

mapreduce/bin/mapred

@@ -34,6 +34,8 @@ function print_usage(){
   echo "  pipes                run a Pipes job"
   echo "  job                  manipulate MapReduce jobs"
   echo "  queue                get information regarding JobQueues"
+  echo "  classpath            prints the class path needed for running"
+  echo "                       mapreduce subcommands"
   echo "  groups               get the groups which users belong to"
   echo ""
   echo "Most commands print help when invoked w/o parameters."
@@ -66,6 +68,8 @@ elif [ "$COMMAND" = "pipes" ] ; then
 elif [ "$COMMAND" = "sampler" ] ; then
   CLASS=org.apache.hadoop.mapred.lib.InputSampler
   HADOOP_OPTS="$HADOOP_OPTS $HADOOP_CLIENT_OPTS"
+elif [ "$COMMAND" = "classpath" ] ; then
+  echo -n 
 elif [ "$COMMAND" = "groups" ] ; then
   CLASS=org.apache.hadoop.mapred.tools.GetGroups
   HADOOP_OPTS="$HADOOP_OPTS $HADOOP_CLIENT_OPTS"
@@ -105,5 +109,11 @@ done
 if $cygwin; then
   CLASSPATH=`cygpath -p -w "$CLASSPATH"`
 fi
+
+if [ "$COMMAND" = "classpath" ] ; then
+  echo $CLASSPATH
+  exit
+fi
+
 export CLASSPATH
 exec "$JAVA" $JAVA_HEAP_MAX $HADOOP_OPTS $CLASS "$@"