docs: public static String exec(Session session, String cmd, Charset charset, OutputStream errStream) {
  		if (null == charset) {
  			charset = CharsetUtil.CHARSET_UTF_8;
  		}
  		ChannelExec channel = (ChannelExec) openChannel(session, ChannelType.EXEC);
  		channel.setCommand(StrUtil.bytes(cmd, charset));
  		channel.setInputStream(null);
  		channel.setErrStream(errStream);
  		InputStream in = null;
  		try {
  			in = channel.getInputStream();
  			return IoUtil.read(in, CharsetUtil.CHARSET_UTF_8);
  		} catch (IOException e) {
  			throw new IORuntimeException(e);
  		} finally {
  			IoUtil.close(in);
  			close(channel);
  		}
  	}