def test_bang(self):
        """
        The I{exec} command is run for lines which start with C{"!"}.
        """
        self.database.addUser(
            getpass.getuser(), 'secret', os.getuid(), 1234, 'foo', 'bar',
            '/bin/sh')

        d = self.client._dispatchCommand("!echo hello")
        d.addCallback(self.assertEqual, b"hello\n")
        return d

        The I{exec} command is run for lines which start with C{"!"}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_cftp.py