code: public void umask(String umask) throws SshException {
  		try {
  			this.umask = Integer.parseInt(umask, 8);
  		} catch (NumberFormatException ex) {
  			throw new SshException(
  					"umask must be 4 digit octal number e.g. 0022",
  					SshException.BAD_API_USAGE);
  		}
  	}
docs: Sets the umask for this client.<br>
  <blockquote>
  
  <pre>
  To give yourself full permissions for both files and directories and
  prevent the group and other users from having access:
  
  umask(&quot;077&quot;);
  
  This subtracts 077 from the system defaults for files and directories
  666 and 777. Giving a default access permissions for your files of
  600 (rw-------) and for directories of 700 (rwx------).
  
  To give all access permissions to the group and allow other users read
  and execute permission:
  
  umask(&quot;002&quot;);
  
  This subtracts 002 from the system defaults to give a default access permission
  for your files of 664 (rw-rw-r--) and for your directories of 775 (rwxrwxr-x).
  
  To give the group and other users all access except write access:
  
  umask(&quot;022&quot;);
  
  This subtracts 022 from the system defaults to give a default access permission
  for your files of 644 (rw-r--r--) and for your directories of 755 (rwxr-xr-x).
  </pre>
  
  </blockquote>
  
  @param umask
  @throws SshException