code: public void changePermissions(SftpFile file, int permissions)
  			throws SftpStatusException, SshException {
  		SftpFileAttributes attrs = new SftpFileAttributes(this,
  				SftpFileAttributes.SSH_FILEXFER_TYPE_UNKNOWN);
  		attrs.setPermissions(new UnsignedInteger32(permissions));
  		setAttributes(file, attrs);
  	}
docs: Change the permissions of a file.
  
  @param file
  the file
  @param permissions
  an integer value containing a file permissions mask
  @throws SshException
  ,SftpStatusException