environment/lib/python2.7/site-packages/IPython/external/pexpect/_pexpect.py
def __fork_pty(self):

        """This implements a substitute for the forkpty system call. This
        should be more portable than the pty.fork() function. Specifically,
        this should work on Solaris.

        Modified 10.06.05 by Geoff Marshall: Implemented __fork_pty() method to
        resolve the issue with Python's pty.fork() not supporting Solaris,
        particularly ssh. Based on patch to posixmodule.c authored by Noah
        Spurrier::

            http://mail.python.org/pipermail/python-dev/2003-May/035281.html

        """

        parent_fd, child_fd = os.openpty()
        if parent_fd < 0 or child_fd < 0:
            raise ExceptionPexpect, "Error! Could not open pty with os.openpty()."

        pid = os.fork()
        if pid < 0:
            raise ExceptionPexpect, "Error! Failed os.fork()."
        elif pid == 0:
            # Child.
            os.close(parent_fd)
            self.__pty_make_controlling_tty(child_fd)

            os.dup2(child_fd, 0)
            os.dup2(child_fd, 1)
            os.dup2(child_fd, 2)

            if child_fd > 2:
                os.close(child_fd)
        else:
            # Parent.
            os.close(child_fd)

        return pid, parent_fd
def __fork_pty(self):

        """This implements a substitute for the forkpty system call. This
        should be more portable than the pty.fork() function. Specifically,
        this should work on Solaris.

        Modified 10.06.05 by Geoff Marshall: Implemented __fork_pty() method to
        resolve the issue with Python's pty.fork() not supporting Solaris,
        particularly ssh. Based on patch to posixmodule.c authored by Noah
        Spurrier::

            http://mail.python.org/pipermail/python-dev/2003-May/035281.html

        """

        parent_fd, child_fd = os.openpty()
        if parent_fd < 0 or child_fd < 0:
            raise ExceptionPexpect, "Error! Could not open pty with os.openpty()."

        pid = os.fork()
        if pid < 0:
            raise ExceptionPexpect, "Error! Failed os.fork()."
        elif pid == 0:
            # Child.
            os.close(parent_fd)
            self.__pty_make_controlling_tty(child_fd)

            os.dup2(child_fd, 0)
            os.dup2(child_fd, 1)
            os.dup2(child_fd, 2)

            if child_fd > 2:
                os.close(child_fd)
        else:
            # Parent.
            os.close(child_fd)

        return pid, parent_fd
This implements a substitute for the forkpty system call. This
        should be more portable than the pty.fork() function. Specifically,
        this should work on Solaris.

        Modified 10.06.05 by Geoff Marshall: Implemented __fork_pty() method to
        resolve the issue with Python's pty.fork() not supporting Solaris,
        particularly ssh. Based on patch to posixmodule.c authored by Noah
        Spurrier::

            http://mail.python.org/pipermail/python-dev/2003-May/035281.html