HBASE-18094 Display the return value of the command append

Signed-off-by: tedyu <yuzhihong@gmail.com>

hbase-shell/src/main/ruby/hbase/table.rb

@@ -244,7 +244,12 @@ EOF
         set_op_ttl(append, ttl) if ttl
       end
       append.add(family, qualifier, value.to_s.to_java_bytes)
-      @table.append(append)
+      result = @table.append(append)
+      return nil if result.isEmpty
+
+      # Fetch cell value
+      cell = result.listCells[0]
+      org.apache.hadoop.hbase.util.Bytes::toStringBinary(cell.getValue)
     end
 
     #----------------------------------------------------------------------------------------------

hbase-shell/src/main/ruby/shell/commands/append.rb

@@ -41,7 +41,9 @@ EOF
 
       def append(table, row, column, value, args={})
         format_simple_command do
-        	table._append_internal(row, column, value, args)
+          if current_value = table._append_internal(row, column, value, args)
+            puts "CURRENT VALUE = #{current_value}"
+          end
         end
       end
     end

hbase-shell/src/test/ruby/hbase/table_test.rb

@@ -183,6 +183,7 @@ module Hbase
 
     define_test "append should work with value" do
       @test_table.append("123", 'x:cnt2', '123')
+      assert_equal("123123", @test_table._append_internal("123", 'x:cnt2', '123'))
     end
     #-------------------------------------------------------------------------------