HADOOP-12374. Updated expunge command description.

(WeiWei Yang via eyang)

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

@@ -307,6 +307,9 @@ Release 2.8.0 - UNRELEASED
 
   BUG FIXES
 
+    HADOOP-12374. Updated expunge command description.
+    (WeiWei Yang via eyang)
+
     HADOOP-12352. Delay in checkpointing Trash can leave trash for 2 intervals
     before deleting (Casey Brotherton via harsh)
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/Delete.java

@@ -215,11 +215,14 @@ class Delete {
     }
   }
 
-  /** empty the trash */
+  // delete files from the trash that are older
+  // than the retention threshold.
   static class Expunge extends FsCommand {
     public static final String NAME = "expunge";
     public static final String USAGE = "";
-    public static final String DESCRIPTION = "Empty the Trash";
+    public static final String DESCRIPTION =
+        "Delete files from the trash that are older " +
+            "than the retention threshold";
 
     // TODO: should probably allow path arguments for the filesystems
     @Override

hadoop-common-project/hadoop-common/src/site/markdown/FileSystemShell.md

@@ -271,7 +271,7 @@ expunge
 
 Usage: `hadoop fs -expunge`
 
-Empty the Trash. Refer to the [HDFS Architecture Guide](../hadoop-hdfs/HdfsDesign.html) for more information on the Trash feature.
+If trash is enabled when a file is deleted, HDFS instead moves the deleted file to a trash directory. This command causes HDFS to permanently delete files from the trash that are older than the retention threshold. Refer to the [File Deletes and Undeletes Guide](../hadoop-hdfs/HdfsDesign.html#File_Deletes_and_Undeletes) in Space Reclamation section for more information on the Trash feature.
 
 find
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