code: def exec_command(self, command, bufsize=-1):
          
          chan = self._transport.open_session()
          chan.exec_command(command)
          stdin = chan.makefile('wb', bufsize)
          stdout = chan.makefile('rb', bufsize)
          stderr = chan.makefile_stderr('rb', bufsize)
          return stdin, stdout, stderr
docs: Execute a command on the SSH server.  A new L{Channel} is opened and
          the requested command is executed.  The command's input and output
          streams are returned as python C{file}-like objects representing
          stdin, stdout, and stderr.
  
          @param command: the command to execute
          @type command: str
          @param bufsize: interpreted the same way as by the built-in C{file()} function in python
          @type bufsize: int
          @return: the stdin, stdout, and stderr of the executing command
          @rtype: tuple(L{ChannelFile}, L{ChannelFile}, L{ChannelFile})
  
          @raise SSHException: if the server fails to execute the command