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<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V2.0//EN" "http://forrest.apache.org/dtd/document-v20.dtd">
<document>
	<header>
		<title>File System Shell Guide</title>
	</header>
	<body>
		<section>
			<title>Overview</title>
			<p>
      The File System (FS) shell includes various shell-like commands that directly
      interact with the Hadoop Distributed File System (HDFS) as well as other file systems that Hadoop supports,  
      such as Local FS, HFTP FS, S3 FS, and others. The FS shell is invoked by: </p>

    <source>bin/hdfs dfs &lt;args&gt;</source>
    
      <p>
      All FS shell commands take path URIs as arguments. The URI
      format is <em>scheme://autority/path</em>. For HDFS the scheme
      is <em>hdfs</em>, and for the Local FS the scheme
      is <em>file</em>. The scheme and authority are optional. If not
      specified, the default scheme specified in the configuration is
      used. An HDFS file or directory such as <em>/parent/child</em>
      can be specified as <em>hdfs://namenodehost/parent/child</em> or
      simply as <em>/parent/child</em> (given that your configuration
      is set to point to <em>hdfs://namenodehost</em>). 
      </p>
     <p>
      Most of the commands in FS shell behave like corresponding Unix
      commands. Differences are described with each of the
      commands. Error information is sent to <em>stderr</em> and the
      output is sent to <em>stdout</em>.
  </p>
  
  
<!-- CAT --> 
		<section>
			<title> cat </title>
			<p>
				<code>Usage: hdfs dfs -cat URI [URI &#x2026;]</code>
			</p>
			<p>
		   Copies source paths to <em>stdout</em>. 
		   </p>
			<p>Example:</p>
			<ul>
				<li>
					<code> hdfs dfs -cat hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2 
		   </code>
				</li>
				<li>
					<code>hdfs dfs -cat file:///file3 /user/hadoop/file4 </code>
				</li>
			</ul>
			<p>Exit Code:<br/>
		   <code> Returns 0 on success and -1 on error. </code></p>
		</section>
		
		
<!-- CHGRP --> 
		<section>
			<title> chgrp </title>
			<p>
				<code>Usage: hdfs dfs -chgrp [-R] GROUP URI [URI &#x2026;]</code>
			</p>
			<p>
	    Change group association of files. With <code>-R</code>, make the change recursively through the directory structure. 
	    The user must be the owner of files, or else a super-user. 
	    Additional information is in the <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_permissions_guide.html">HDFS Permissions Guide</a>.
	    </p>
		</section>
		<section>
			<title> chmod </title>
			<p>
				<code>Usage: hdfs dfs -chmod [-R] &lt;MODE[,MODE]... | OCTALMODE&gt; URI [URI &#x2026;]</code>
			</p>
			<p>
	    Change the permissions of files. With <code>-R</code>, make the change recursively through the directory structure. 
	    The user must be the owner of the file, or else a super-user. 
	    Additional information is in the <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_permissions_guide.html">HDFS Permissions Guide</a>.
	    </p>
		</section>
		
		
<!-- CHOWN --> 		
		<section>
			<title> chown </title>
			<p>
				<code>Usage: hdfs dfs -chown [-R] [OWNER][:[GROUP]] URI [URI ]</code>
			</p>
			<p>
	    Change the owner of files. With <code>-R</code>, make the change recursively through the directory structure. 
	    The user must be a super-user. 
	    Additional information is in the <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_permissions_guide.html">HDFS Permissions Guide</a>.
	    </p>
		</section>
		
		
<!-- COPYFROMLOCAL --> 		
		<section>
			<title>copyFromLocal</title>
			<p>
				<code>Usage: hdfs dfs -copyFromLocal &lt;localsrc&gt; URI</code>
			</p>
			<p>Similar to <a href="#put"><strong>put</strong></a> command, except that the source is restricted to a local file reference. </p>
		</section>
		
		
<!-- COPYTOLOCAL -->
		<section>
			<title> copyToLocal</title>
			<p>
				<code>Usage: hdfs dfs -copyToLocal [-ignorecrc] [-crc] URI &lt;localdst&gt;</code>
			</p>
			<p> Similar to <a href="#get"><strong>get</strong></a> command, except that the destination is restricted to a local file reference.</p>
		</section>
		
<!-- COUNT -->		
		<section>
			<title> count </title>
			<p>
				<code>Usage: hdfs dfs -count [-q]  &lt;paths&gt;</code>
			</p>
			<p>
				Count the number of directories, files and bytes under the paths that match the specified file pattern. <br/><br/>
				The output columns with <code>-count </code> are:<br/><br/>
				<code>DIR_COUNT, FILE_COUNT, CONTENT_SIZE FILE_NAME</code> <br/><br/>
				The output columns with <code>-count -q</code> are:<br/><br/>
				<code>QUOTA, REMAINING_QUATA, SPACE_QUOTA, REMAINING_SPACE_QUOTA, 
				DIR_COUNT, FILE_COUNT, CONTENT_SIZE, FILE_NAME</code>
		   </p>
			<p>Example:</p>
			<ul>
				<li>
					<code> hdfs dfs -count hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2 
		   </code>
				</li>
				<li>
					<code> hdfs dfs -count -q hdfs://nn1.example.com/file1
		   </code>
				</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code> Returns 0 on success and -1 on error.</code>
			</p>
		</section>
		
		
<!-- CP -->		
		<section>
			<title> cp </title>
			<p>
				<code>Usage: hdfs dfs -cp URI [URI &#x2026;] &lt;dest&gt;</code>
			</p>
			<p>
	    Copy files from source to destination. This command allows multiple sources as well in which case the destination must be a directory.
	    <br/>
	    Example:</p>
			<ul>
				<li>
					<code> hdfs dfs -cp /user/hadoop/file1 /user/hadoop/file2</code>
				</li>
				<li>
					<code> hdfs dfs -cp /user/hadoop/file1 /user/hadoop/file2 /user/hadoop/dir </code>
				</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code> Returns 0 on success and -1 on error.</code>
			</p>
		</section>
		
<!-- DU -->
		<section>
			<title>du</title>
			<p>
				<code>Usage: hdfs dfs -du [-s] [-h] URI [URI &#x2026;]</code>
			</p>
			<p>
	     Displays sizes of files and directories contained in the given directory or the length of a file in case its just a file.</p>
             <p>Options:</p>
             <ul>
             <li>The <code>-s</code> option will result in an aggregate summary of file lengths being displayed, rather than the individual files.</li>
             <li>The <code>-h</code> option will format file sizes in a &quot;human-readable&quot; fashion (e.g 64.0m instead of 67108864)</li>
             </ul>
             <p>
	     Example:<br/><code>hdfs dfs -du /user/hadoop/dir1 /user/hadoop/file1 hdfs://nn.example.com/user/hadoop/dir1</code><br/>
	     Exit Code:<br/><code> Returns 0 on success and -1 on error. </code><br/></p>
		</section>
		
<!-- DUS -->		
		<section>
			<title> dus </title>
			<p>
				<code>Usage: hdfs dfs -dus &lt;args&gt;</code>
			</p>
			<p>
	    Displays a summary of file lengths. This is an alternate form of <code>hdfs dfs -du -s</code>.
	   </p>
		</section>
		
		
<!-- EXPUNGE -->		
		<section>
			<title> expunge </title>
			<p>
				<code>Usage: hdfs dfs -expunge</code>
			</p>
			<p>Empty the Trash. Refer to the <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_design.html">HDFS Architecture Guide</a>
			 for more information on the Trash feature.</p>
		</section>


<!-- GET -->			
		<section>
			<title> get </title>
			<p>
				<code>Usage: hdfs dfs -get [-ignorecrc] [-crc] &lt;src&gt; &lt;localdst&gt;</code>
				<br/>
			</p>
			<p>
	   Copy files to the local file system. Files that fail the CRC check may be copied with the  
	   <code>-ignorecrc</code> option. Files and CRCs may be copied using the 
	   <code>-crc</code> option.
	  </p>
			<p>Example:</p>
			<ul>
				<li>
					<code> hdfs dfs -get /user/hadoop/file localfile </code>
				</li>
				<li>
					<code> hdfs dfs -get hdfs://nn.example.com/user/hadoop/file localfile</code>
				</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code> Returns 0 on success and -1 on error. </code>
			</p>
		</section>
		
		
<!-- GETMERGE -->			
		<section>
			<title> getmerge </title>
			<p>
				<code>Usage: hdfs dfs -getmerge [-nl] &lt;src&gt; &lt;localdst&gt;</code>
			</p>
			<p>
	  Takes a source directory and a destination file as input and concatenates files in src into the destination local file. 
	  Optionally <code>-nl</code> flag can be set to enable adding a newline character at the end of each file during merge.
	  </p>
		</section>
		
		
<!-- LS -->		
       <section>
           <title>ls</title>
           <p>
               <code>Usage: hdfs dfs -ls [-d] [-h] [-R] &lt;args&gt;</code>
           </p>
           <p>For a file returns stat on the file with the following format:</p>
           <p>
               <code>permissions number_of_replicas userid  groupid  filesize modification_date modification_time filename</code>
           </p>
           <p>For a directory it returns list of its direct children as in unix.A directory is listed as:</p>
           <p>
               <code>permissions userid groupid modification_date modification_time dirname</code>
           </p>
           <p>Options:</p>
             <ul>
               <li><code>-d</code>  Directories are listed as plain files</li>
               <li><code>-h</code>  Format file sizes in a &quot;human-readable&quot; fashion (e.g 64.0m instead of 67108864)</li>
               <li><code>-R</code>  Recursively list subdirectories encountered</li>
             </ul>
           <p>Example:</p>
           <p>
               <code>hdfs dfs -ls /user/hadoop/file1 </code>
           </p>
           <p>Exit Code:</p>
           <p>
               <code>Returns 0 on success and -1 on error.</code>
           </p>
       </section>
       
       
<!-- LSR -->       
		<section>
			<title>lsr</title>
			<p><code>Usage: hdfs dfs -lsr &lt;args&gt;</code><br/>
	      Recursive version of <code>ls</code>. Similar to Unix <code>ls -R</code>.
	      </p>
		</section>
		
		
<!-- MKDIR -->  
		<section>
			<title> mkdir </title>
			<p>
				<code>Usage: hdfs dfs -mkdir &lt;paths&gt;</code>
				<br/>
			</p>
			<p>
	   Takes path uri's as argument and creates directories. The behavior is much like unix mkdir -p creating parent directories along the path.
	  </p>
			<p>Example:</p>
			<ul>
				<li>
					<code>hdfs dfs -mkdir /user/hadoop/dir1 /user/hadoop/dir2 </code>
				</li>
				<li>
					<code>hdfs dfs -mkdir hdfs://nn1.example.com/user/hadoop/dir hdfs://nn2.example.com/user/hadoop/dir
	  </code>
				</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code>Returns 0 on success and -1 on error.</code>
			</p>
		</section>
		
		
<!-- MOVEFROMLOCAL -->  
		<section>
			<title> moveFromLocal </title>
			<p>
				<code>Usage: dfs -moveFromLocal &lt;localsrc&gt; &lt;dst&gt;</code>
			</p>
			<p>Similar to <a href="#put"><strong>put</strong></a> command, except that the source <code>localsrc</code> is deleted after it's copied. </p>
		</section>
		
		
<!-- MOVETOLOCAL -->  
		<section>
			<title> moveToLocal</title>
			<p>
				<code>Usage: hdfs dfs -moveToLocal [-crc] &lt;src&gt; &lt;dst&gt;</code>
			</p>
			<p>Displays a "Not implemented yet" message.</p>
		</section>
		
		
<!-- MV -->  
		<section>
			<title> mv </title>
			<p>
				<code>Usage: hdfs dfs -mv URI [URI &#x2026;] &lt;dest&gt;</code>
			</p>
			<p>
	    Moves files from source to destination. This command allows multiple sources as well in which case the destination needs to be a directory. 
	    Moving files across file systems is not permitted.
	    <br/>
	    Example:
	    </p>
			<ul>
				<li>
					<code> hdfs dfs -mv /user/hadoop/file1 /user/hadoop/file2</code>
				</li>
				<li>
					<code> hdfs dfs -mv hdfs://nn.example.com/file1 hdfs://nn.example.com/file2 hdfs://nn.example.com/file3 hdfs://nn.example.com/dir1</code>
				</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code> Returns 0 on success and -1 on error.</code>
			</p>
		</section>
		
		
<!-- PUT --> 
		<section>
			<title> put </title>
			<p>
				<code>Usage: hdfs dfs -put &lt;localsrc&gt; ... &lt;dst&gt;</code>
			</p>
			<p>Copy single src, or multiple srcs from local file system to the destination file system. 
			Also reads input from stdin and writes to destination file system.<br/>
	   </p>
			<ul>
				<li>
					<code> hdfs dfs -put localfile /user/hadoop/hadoopfile</code>
				</li>
				<li>
					<code> hdfs dfs -put localfile1 localfile2 /user/hadoop/hadoopdir</code>
				</li>
				<li>
					<code> hdfs dfs -put localfile hdfs://nn.example.com/hadoop/hadoopfile</code>
				</li>
				<li><code>hdfs dfs -put - hdfs://nn.example.com/hadoop/hadoopfile</code><br/>Reads the input from stdin.</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code> Returns 0 on success and -1 on error. </code>
			</p>
		</section>
		
		
<!-- RM --> 
		<section>
			<title> rm </title>
			<p>
				<code>Usage: hdfs dfs -rm [-skipTrash] URI [URI &#x2026;] </code>
			</p>
			<p>
	   Delete files specified as args. Only deletes non empty directory and files. If the <code>-skipTrash</code> option
	   is specified, the trash, if enabled, will be bypassed and the specified file(s) deleted immediately.  	This can be
		   useful when it is necessary to delete files from an over-quota directory.
	   Refer to rmr for recursive deletes.<br/>
	   Example:
	   </p>
			<ul>
				<li>
					<code> hdfs dfs -rm hdfs://nn.example.com/file /user/hadoop/emptydir </code>
				</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code> Returns 0 on success and -1 on error.</code>
			</p>
		</section>
		
		
<!-- RMR --> 
		<section>
			<title> rmr </title>
			<p>
				<code>Usage: hdfs dfs -rmr [-skipTrash] URI [URI &#x2026;]</code>
			</p>
			<p>Recursive version of delete. If the <code>-skipTrash</code> option
		   is specified, the trash, if enabled, will be bypassed and the specified file(s) deleted immediately. This can be
		   useful when it is necessary to delete files from an over-quota directory.<br/>
	   Example:
	   </p>
			<ul>
				<li>
					<code> hdfs dfs -rmr /user/hadoop/dir </code>
				</li>
				<li>
					<code> hdfs dfs -rmr hdfs://nn.example.com/user/hadoop/dir </code>
				</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code> Returns 0 on success and -1 on error. </code>
			</p>
		</section>
		
		
<!-- SETREP --> 
		<section>
			<title> setrep </title>
			<p>
				<code>Usage: hdfs dfs -setrep [-R] &lt;path&gt;</code>
			</p>
			<p>
	   Changes the replication factor of a file. -R option is for recursively increasing the replication factor of files within a directory.
	  </p>
			<p>Example:</p>
			<ul>
				<li>
					<code> hdfs dfs -setrep -w 3 -R /user/hadoop/dir1 </code>
				</li>
			</ul>
			<p>Exit Code:</p>
			<p>
				<code>Returns 0 on success and -1 on error. </code>
			</p>
		</section>
		
		
<!-- STAT --> 
		<section>
			<title> stat </title>
			<p>
				<code>Usage: hdfs dfs -stat [format] URI [URI &#x2026;]</code>
			</p>
			<p>Print statistics about the file/directory matching the given URI pattern in the specified format.</p>
			<p>Format accepts:</p>
			  <ul>
			    <li>filesize in blocks (%b)</li>
			    <li>filename (%n)</li>
		      <li>block size (%o)</li>
		      <li>replication (%r)</li>
		      <li>modification date, formatted as Y-M-D H:M:S (%y)</li>
		      <li>modification date, in epoch seconds (%Y)</li>
        </ul>
			<p>Example:</p>
			<ul>
        <li>
          <code> hdfs dfs -stat path </code>
        </li>
				<li>
					<code> hdfs dfs -stat %y path </code>
				</li>
        <li>
          <code> hdfs dfs -stat '%b %r' path </code>
        </li>
			</ul>
			<p>Exit Code:<br/>
	   <code> Returns 0 on success and -1 on error.</code></p>
		</section>
		
		
<!-- TAIL--> 
		<section>
			<title> tail </title>
			<p>
				<code>Usage: hdfs dfs -tail [-f] URI </code>
			</p>
			<p>
	   Displays last kilobyte of the file to stdout. -f option can be used as in Unix.
	   </p>
			<p>Example:</p>
			<ul>
				<li>
					<code> hdfs dfs -tail pathname </code>
				</li>
			</ul>
			<p>Exit Code: <br/>
	   <code> Returns 0 on success and -1 on error.</code></p>
		</section>
		
		
<!-- TEST --> 
		<section>
			<title> test </title>
			<p>
				<code>Usage: hdfs dfs -test -[ezd] URI</code>
			</p>
			<p>
	   Options: <br/>
	   -e check to see if the file exists. Return 0 if true. <br/>
	   -z check to see if the file is zero length. Return 0 if true. <br/>
	   -d check to see if the path is directory. Return 0 if true. <br/></p>
			<p>Example:</p>
			<ul>
				<li>
					<code> hdfs dfs -test -e filename </code>
				</li>
			</ul>
		</section>
		
		
<!-- TEXT --> 
		<section>
			<title> text </title>
			<p>
				<code>Usage: hdfs dfs -text &lt;src&gt;</code>
				<br/>
			</p>
			<p>
	   Takes a source file and outputs the file in text format. The allowed formats are zip and TextRecordInputStream.
	  </p>
		</section>
		
		
<!-- TOUCHZ --> 
		<section>
			<title> touchz </title>
			<p>
				<code>Usage: hdfs dfs -touchz URI [URI &#x2026;]</code>
				<br/>
			</p>
			<p>
	   Create a file of zero length.
	   </p>
			<p>Example:</p>
			<ul>
				<li>
					<code> hadoop -touchz pathname </code>
				</li>
			</ul>
			<p>Exit Code:<br/>
	   <code> Returns 0 on success and -1 on error.</code></p>
		</section>
        </section>
	</body>
</document>
