def _do_shell(self, line):
        """Send a command to the Unix shell.\n==> Usage: shell ls ~"""
        if not line:
            return
        sp = Popen(line,
                   shell=True,
                   stdin=PIPE,
                   stdout=PIPE,
                   stderr=PIPE,
                   close_fds=not WINDOWS)
        (fo, fe) = (sp.stdout, sp.stderr)
        if PY2:
            out = fo.read().strip(EOL)
            err = fe.read().strip(EOL)
        else:
            out = fo.read().decode("utf-8")
            err = fe.read().decode("utf-8")
        if out:
            print(out)
            return
        if err:
            print(err.replace('isbn_', ''))
Send a command to the Unix shell.\n==> Usage: shell ls ~