HBASE-21283 Add new shell command 'rit' for listing regions in transition

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

@@ -1063,6 +1063,12 @@ module Hbase
         Pattern.compile(snapshotNameRegex)).to_a
     end
 
+    #----------------------------------------------------------------------------------------------
+    # Returns the ClusterStatus of the cluster
+    def getClusterStatus
+      @admin.getClusterStatus
+    end
+
     #----------------------------------------------------------------------------------------------
     # Returns a list of regionservers
     def getRegionServers

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

@@ -361,6 +361,7 @@ Shell.load_command_group(
     clear_block_cache
     stop_master
     stop_regionserver
+    rit
   ],
   # TODO: remove older hlog_roll command
   aliases: {

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

@@ -0,0 +1,40 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+module Shell
+  module Commands
+    # List all regions in transition
+    class Rit < Command
+      def help
+        <<-EOF
+List all regions in transition.
+Examples:
+  hbase> rit
+        EOF
+      end
+
+      def command
+        rit = admin.getClusterStatus.getRegionStatesInTransition
+        rit.each do |v|
+          formatter.row([v.toDescriptiveString])
+        end
+        formatter.footer(rit.size)
+      end
+    end
+  end
+end