title: Trying to replicate IBM Mainframe SFTP upload with JSch ChannelSftp
body: <p>I am trying to use Jsch Sftp Channel to upload a file to an IBM Mainframe, and the directory has to be "//", where the mainframe will automatically route the file where it needs to go.</p>
  
  <p>In an sftp command session on the IBM mainframe, I can do this:</p>
  
  <pre><code>sftp myuser@1.2.3.4
  connecting to 1.2.3.4...
  myuser@1.2.3.4's password:
  sftp&gt; pwd
  Remote working directory: /users/home/myuser
  sftp&gt; cd //
  sftp&gt; pwd
  Remote working directory: //
  sftp&gt; put "#12345.abcdef.xxx.xxx"
  uploading #12345.abcdef.xxx.xxx to //#12345.abcdef.xxx.xxx
  #12345.abcdef.xxx.xxx               100%  403   0.4KB/s 00:00
  </code></pre>
  
  <p>So I created a JSch sftp session (version 0.1.5.1) to attempt the same upload, but it does not work:</p>
  
  <pre><code>JSch jsch = new JSch();
  Session session = jsch.getSession("myuser", "1.2.3.4");
  session.setPassword("mypass");
  session.connect();
  Channel channel = session.openChannel("sftp");
  channel.connect();
  
  ChannelSftp sftp = (ChannelSftp)channel;
  log.info(" user home pwd " + sftp.pwd());  //prints /users/home/myuser
  sftp.cd("//")
  log.info(" pwd after cd " + sftp.pwd()); //only prints /
  sftp.put(filename);   //get sftp error, no such file
  </code></pre>
  
  <p>So I cannot get to that // structure through the JSch library.  Is there a certain mode or flag that needs to be set for the sftp session to know it's on a mainframe?</p>
  
  <p>I have no issue at all doing a JSch sftp session to my /users/home/myuser directory, just can't get it to go to the // </p>