Merge remote-tracking branch 'origin/master' into issue-104-cannot-exec-setuids

Conflicts:
	pexpect/__init__.py

10 files changed, 1656 insertions, 1904 deletions

diff --git a/pexpect/__init__.py b/pexpect/__init__.py
index 5583be7..c906e89 100644
--- a/pexpect/__init__.py
+++ b/pexpect/__init__.py
@@ -63,83 +63,20 @@ PEXPECT LICENSE
 
 '''
 
-try:
-    import os
-    import sys
-    import time
-    import select
-    import re
-    import struct
-    import resource
-    import types
-    import pty
-    import tty
-    import termios
-    import fcntl
-    import errno
-    import traceback
-    import signal
-    import codecs
-    import stat
-except ImportError:  # pragma: no cover
-    err = sys.exc_info()[1]
-    raise ImportError(str(err) + '''
+import sys
+import types
 
-A critical module was not found. Probably this operating system does not
-support it. Pexpect is intended for UNIX-like operating systems.''')
-
-from .expect import Expecter
+from .exceptions import ExceptionPexpect, EOF, TIMEOUT
+from .utils import split_command_line, which, is_executable_file
+from .pty_spawn import spawn, spawnu, PY3
+from .expect import Expecter, searcher_re, searcher_string
 
 __version__ = '3.3'
 __revision__ = ''
 __all__ = ['ExceptionPexpect', 'EOF', 'TIMEOUT', 'spawn', 'spawnu', 'run', 'runu',
            'which', 'split_command_line', '__version__', '__revision__']
 
-PY3 = (sys.version_info[0] >= 3)
-
-# Exception classes used by this module.
-class ExceptionPexpect(Exception):
-    '''Base class for all exceptions raised by this module.
-    '''
-
-    def __init__(self, value):
-        super(ExceptionPexpect, self).__init__(value)
-        self.value = value
-
-    def __str__(self):
-        return str(self.value)
-
-    def get_trace(self):
-        '''This returns an abbreviated stack trace with lines that only concern
-        the caller. In other words, the stack trace inside the Pexpect module
-        is not included. '''
-
-        tblist = traceback.extract_tb(sys.exc_info()[2])
-        tblist = [item for item in tblist if ('pexpect/__init__' not in item[0])
-                                           and ('pexpect/expect' not in item[0])]
-        tblist = traceback.format_list(tblist)
-        return ''.join(tblist)
-
-
-class EOF(ExceptionPexpect):
-    '''Raised when EOF is read from a child.
-    This usually means the child has exited.'''
-
-
-class TIMEOUT(ExceptionPexpect):
-    '''Raised when a read time exceeds the timeout. '''
-
-##class TIMEOUT_PATTERN(TIMEOUT):
-##    '''Raised when the pattern match time exceeds the timeout.
-##    This is different than a read TIMEOUT because the child process may
-##    give output, thus never give a TIMEOUT, but the output
-##    may never match a pattern.
-##    '''
-##class MAXBUFFER(ExceptionPexpect):
-##    '''Raised when a buffer fills before matching an expected pattern.'''
-
-
-def run(command, timeout=-1, withexitstatus=False, events=None,
+def run(command, timeout=30, withexitstatus=False, events=None,
         extra_args=None, logfile=None, cwd=None, env=None):
 
     '''
@@ -227,7 +164,7 @@ def run(command, timeout=-1, withexitstatus=False, events=None,
                 events=events, extra_args=extra_args, logfile=logfile, cwd=cwd,
                 env=env, _spawn=spawn)
 
-def runu(command, timeout=-1, withexitstatus=False, events=None,
+def runu(command, timeout=30, withexitstatus=False, events=None,
         extra_args=None, logfile=None, cwd=None, env=None, **kwargs):
     """This offers the same interface as :func:`run`, but using unicode.
 
@@ -292,1816 +229,4 @@ def _run(command, timeout, withexitstatus, events, extra_args, logfile, cwd,
     else:
         return child_result
 
-class spawn(object):
-    '''This is the main class interface for Pexpect. Use this class to start
-    and control child applications. '''
-    string_type = bytes
-    if PY3:
-        allowed_string_types = (bytes, str)
-        @staticmethod
-        def _chr(c):
-            return bytes([c])
-        linesep = os.linesep.encode('ascii')
-        crlf = '\r\n'.encode('ascii')
-
-        @staticmethod
-        def write_to_stdout(b):
-            try:
-                return sys.stdout.buffer.write(b)
-            except AttributeError:
-                # If stdout has been replaced, it may not have .buffer
-                return sys.stdout.write(b.decode('ascii', 'replace'))
-    else:
-        allowed_string_types = (basestring,)  # analysis:ignore
-        _chr = staticmethod(chr)
-        linesep = os.linesep
-        crlf = '\r\n'
-        write_to_stdout = sys.stdout.write
-
-    encoding = None
-
-    def __init__(self, command, args=[], timeout=30, maxread=2000,
-        searchwindowsize=None, logfile=None, cwd=None, env=None,
-        ignore_sighup=True, echo=True):
-
-        '''This is the constructor. The command parameter may be a string that
-        includes a command and any arguments to the command. For example::
-
-            child = pexpect.spawn('/usr/bin/ftp')
-            child = pexpect.spawn('/usr/bin/ssh user@example.com')
-            child = pexpect.spawn('ls -latr /tmp')
-
-        You may also construct it with a list of arguments like so::
-
-            child = pexpect.spawn('/usr/bin/ftp', [])
-            child = pexpect.spawn('/usr/bin/ssh', ['user@example.com'])
-            child = pexpect.spawn('ls', ['-latr', '/tmp'])
-
-        After this the child application will be created and will be ready to
-        talk to. For normal use, see expect() and send() and sendline().
-
-        Remember that Pexpect does NOT interpret shell meta characters such as
-        redirect, pipe, or wild cards (``>``, ``|``, or ``*``). This is a
-        common mistake.  If you want to run a command and pipe it through
-        another command then you must also start a shell. For example::
-
-            child = pexpect.spawn('/bin/bash -c "ls -l | grep LOG > logs.txt"')
-            child.expect(pexpect.EOF)
-
-        The second form of spawn (where you pass a list of arguments) is useful
-        in situations where you wish to spawn a command and pass it its own
-        argument list. This can make syntax more clear. For example, the
-        following is equivalent to the previous example::
-
-            shell_cmd = 'ls -l | grep LOG > logs.txt'
-            child = pexpect.spawn('/bin/bash', ['-c', shell_cmd])
-            child.expect(pexpect.EOF)
-
-        The maxread attribute sets the read buffer size. This is maximum number
-        of bytes that Pexpect will try to read from a TTY at one time. Setting
-        the maxread size to 1 will turn off buffering. Setting the maxread
-        value higher may help performance in cases where large amounts of
-        output are read back from the child. This feature is useful in
-        conjunction with searchwindowsize.
-
-        The searchwindowsize attribute sets the how far back in the incoming
-        seach buffer Pexpect will search for pattern matches. Every time
-        Pexpect reads some data from the child it will append the data to the
-        incoming buffer. The default is to search from the beginning of the
-        incoming buffer each time new data is read from the child. But this is
-        very inefficient if you are running a command that generates a large
-        amount of data where you want to match. The searchwindowsize does not
-        affect the size of the incoming data buffer. You will still have
-        access to the full buffer after expect() returns.
-
-        The logfile member turns on or off logging. All input and output will
-        be copied to the given file object. Set logfile to None to stop
-        logging. This is the default. Set logfile to sys.stdout to echo
-        everything to standard output. The logfile is flushed after each write.
-
-        Example log input and output to a file::
-
-            child = pexpect.spawn('some_command')
-            fout = open('mylog.txt','wb')
-            child.logfile = fout
-
-        Example log to stdout::
-
-            # In Python 2:
-            child = pexpect.spawn('some_command')
-            child.logfile = sys.stdout
-
-            # In Python 3, spawnu should be used to give str to stdout:
-            child = pexpect.spawnu('some_command')
-            child.logfile = sys.stdout
-
-        The logfile_read and logfile_send members can be used to separately log
-        the input from the child and output sent to the child. Sometimes you
-        don't want to see everything you write to the child. You only want to
-        log what the child sends back. For example::
-
-            child = pexpect.spawn('some_command')
-            child.logfile_read = sys.stdout
-        
-        Remember to use spawnu instead of spawn for the above code if you are
-        using Python 3.
-
-        To separately log output sent to the child use logfile_send::
-
-            child.logfile_send = fout
-
-        If ``ignore_sighup`` is True, the child process will ignore SIGHUP
-        signals. For now, the default is True, to preserve the behaviour of
-        earlier versions of Pexpect, but you should pass this explicitly if you
-        want to rely on it.
-
-        The delaybeforesend helps overcome a weird behavior that many users
-        were experiencing. The typical problem was that a user would expect() a
-        "Password:" prompt and then immediately call sendline() to send the
-        password. The user would then see that their password was echoed back
-        to them. Passwords don't normally echo. The problem is caused by the
-        fact that most applications print out the "Password" prompt and then
-        turn off stdin echo, but if you send your password before the
-        application turned off echo, then you get your password echoed.
-        Normally this wouldn't be a problem when interacting with a human at a
-        real keyboard. If you introduce a slight delay just before writing then
-        this seems to clear up the problem. This was such a common problem for
-        many users that I decided that the default pexpect behavior should be
-        to sleep just before writing to the child application. 1/20th of a
-        second (50 ms) seems to be enough to clear up the problem. You can set
-        delaybeforesend to 0 to return to the old behavior. Most Linux machines
-        don't like this to be below 0.03. I don't know why.
-
-        Note that spawn is clever about finding commands on your path.
-        It uses the same logic that "which" uses to find executables.
-
-        If you wish to get the exit status of the child you must call the
-        close() method. The exit or signal status of the child will be stored
-        in self.exitstatus or self.signalstatus. If the child exited normally
-        then exitstatus will store the exit return code and signalstatus will
-        be None. If the child was terminated abnormally with a signal then
-        signalstatus will store the signal value and exitstatus will be None.
-        If you need more detail you can also read the self.status member which
-        stores the status returned by os.waitpid. You can interpret this using
-        os.WIFEXITED/os.WEXITSTATUS or os.WIFSIGNALED/os.TERMSIG.
-
-        The echo attribute may be set to False to disable echoing of input.
-        As a pseudo-terminal, all input echoed by the "keyboard" (send()
-        or sendline()) will be repeated to output.  For many cases, it is
-        not desirable to have echo enabled, and it may be later disabled
-        using setecho(False) followed by waitnoecho().  However, for some
-        platforms such as Solaris, this is not possible, and should be
-        disabled immediately on spawn.
-        '''
-
-        self.STDIN_FILENO = pty.STDIN_FILENO
-        self.STDOUT_FILENO = pty.STDOUT_FILENO
-        self.STDERR_FILENO = pty.STDERR_FILENO
-        self.stdin = sys.stdin
-        self.stdout = sys.stdout
-        self.stderr = sys.stderr
-
-        self.searcher = None
-        self.ignorecase = False
-        self.before = None
-        self.after = None
-        self.match = None
-        self.match_index = None
-        self.terminated = True
-        self.exitstatus = None
-        self.signalstatus = None
-        # status returned by os.waitpid
-        self.status = None
-        self.flag_eof = False
-        self.pid = None
-        # the child file descriptor is initially closed
-        self.child_fd = -1
-        self.timeout = timeout
-        self.delimiter = EOF
-        self.logfile = logfile
-        # input from child (read_nonblocking)
-        self.logfile_read = None
-        # output to send (send, sendline)
-        self.logfile_send = None
-        # max bytes to read at one time into buffer
-        self.maxread = maxread
-        # This is the read buffer. See maxread.
-        self.buffer = self.string_type()
-        # Data before searchwindowsize point is preserved, but not searched.
-        self.searchwindowsize = searchwindowsize
-        # Delay used before sending data to child. Time in seconds.
-        # Most Linux machines don't like this to be below 0.03 (30 ms).
-        self.delaybeforesend = 0.05
-        # Used by close() to give kernel time to update process status.
-        # Time in seconds.
-        self.delayafterclose = 0.1
-        # Used by terminate() to give kernel time to update process status.
-        # Time in seconds.
-        self.delayafterterminate = 0.1
-        self.softspace = False
-        self.name = '<' + repr(self) + '>'
-        self.closed = True
-        self.cwd = cwd
-        self.env = env
-        self.echo = echo
-        self.ignore_sighup = ignore_sighup
-        _platform = sys.platform.lower()
-        # This flags if we are running on irix
-        self.__irix_hack = _platform.startswith('irix')
-        # Solaris uses internal __fork_pty(). All others use pty.fork().
-        self.use_native_pty_fork = not (
-                _platform.startswith('solaris') or
-                _platform.startswith('sunos'))
-        # inherit EOF and INTR definitions from controlling process.
-        try:
-            from termios import VEOF, VINTR
-            try:
-                fd = sys.__stdin__.fileno()
-            except ValueError:
-                # ValueError: I/O operation on closed file
-                fd = sys.__stdout__.fileno()
-            self._INTR = ord(termios.tcgetattr(fd)[6][VINTR])
-            self._EOF = ord(termios.tcgetattr(fd)[6][VEOF])
-        except (ImportError, OSError, IOError, ValueError, termios.error):
-            # unless the controlling process is also not a terminal,
-            # such as cron(1), or when stdin and stdout are both closed.
-            # Fall-back to using CEOF and CINTR. There
-            try:
-                from termios import CEOF, CINTR
-                (self._INTR, self._EOF) = (CINTR, CEOF)
-            except ImportError:
-                #                         ^C, ^D
-                (self._INTR, self._EOF) = (3, 4)
-        # Support subclasses that do not use command or args.
-        if command is None:
-            self.command = None
-            self.args = None
-            self.name = '<pexpect factory incomplete>'
-        else:
-            self._spawn(command, args)
-
-    @staticmethod
-    def _coerce_expect_string(s):
-        if not isinstance(s, bytes):
-            return s.encode('ascii')
-        return s
-
-    @staticmethod
-    def _coerce_send_string(s):
-        if not isinstance(s, bytes):
-            return s.encode('utf-8')
-        return s
-
-    @staticmethod
-    def _coerce_read_string(s):
-        return s
-
-    def __del__(self):
-        '''This makes sure that no system resources are left open. Python only
-        garbage collects Python objects. OS file descriptors are not Python
-        objects, so they must be handled explicitly. If the child file
-        descriptor was opened outside of this class (passed to the constructor)
-        then this does not close it. '''
-
-        if not self.closed:
-            # It is possible for __del__ methods to execute during the
-            # teardown of the Python VM itself. Thus self.close() may
-            # trigger an exception because os.close may be None.
-            try:
-                self.close()
-            # which exception, shouldnt' we catch explicitly .. ?
-            except:
-                pass
-
-    def __str__(self):
-        '''This returns a human-readable string that represents the state of
-        the object. '''
-
-        s = []
-        s.append(repr(self))
-        s.append('version: ' + __version__)
-        s.append('command: ' + str(self.command))
-        s.append('args: %r' % (self.args,))
-        s.append('searcher: %r' % (self.searcher,))
-        s.append('buffer (last 100 chars): %r' % (
-            self.buffer[-100:] if self.buffer else self.buffer,))
-        s.append('before (last 100 chars): %r' % (
-            self.before[-100:] if self.before else self.before,))
-        s.append('after: %r' % (self.after,))
-        s.append('match: %r' % (self.match,))
-        s.append('match_index: ' + str(self.match_index))
-        s.append('exitstatus: ' + str(self.exitstatus))
-        s.append('flag_eof: ' + str(self.flag_eof))
-        s.append('pid: ' + str(self.pid))
-        s.append('child_fd: ' + str(self.child_fd))
-        s.append('closed: ' + str(self.closed))
-        s.append('timeout: ' + str(self.timeout))
-        s.append('delimiter: ' + str(self.delimiter))
-        s.append('logfile: ' + str(self.logfile))
-        s.append('logfile_read: ' + str(self.logfile_read))
-        s.append('logfile_send: ' + str(self.logfile_send))
-        s.append('maxread: ' + str(self.maxread))
-        s.append('ignorecase: ' + str(self.ignorecase))
-        s.append('searchwindowsize: ' + str(self.searchwindowsize))
-        s.append('delaybeforesend: ' + str(self.delaybeforesend))
-        s.append('delayafterclose: ' + str(self.delayafterclose))
-        s.append('delayafterterminate: ' + str(self.delayafterterminate))
-        return '\n'.join(s)
-
-    def _spawn(self, command, args=[]):
-        '''This starts the given command in a child process. This does all the
-        fork/exec type of stuff for a pty. This is called by __init__. If args
-        is empty then command will be parsed (split on spaces) and args will be
-        set to parsed arguments. '''
-
-        # The pid and child_fd of this object get set by this method.
-        # Note that it is difficult for this method to fail.
-        # You cannot detect if the child process cannot start.
-        # So the only way you can tell if the child process started
-        # or not is to try to read from the file descriptor. If you get
-        # EOF immediately then it means that the child is already dead.
-        # That may not necessarily be bad because you may have spawned a child
-        # that performs some task; creates no stdout output; and then dies.
-
-        # If command is an int type then it may represent a file descriptor.
-        if isinstance(command, type(0)):
-            raise ExceptionPexpect('Command is an int type. ' +
-                    'If this is a file descriptor then maybe you want to ' +
-                    'use fdpexpect.fdspawn which takes an existing ' +
-                    'file descriptor instead of a command string.')
-
-        if not isinstance(args, type([])):
-            raise TypeError('The argument, args, must be a list.')
-
-        if args == []:
-            self.args = split_command_line(command)
-            self.command = self.args[0]
-        else:
-            # Make a shallow copy of the args list.
-            self.args = args[:]
-            self.args.insert(0, command)
-            self.command = command
-
-        command_with_path = which(self.command)
-        if command_with_path is None:
-            raise ExceptionPexpect('The command was not found or was not ' +
-                    'executable: %s.' % self.command)
-        self.command = command_with_path
-        self.args[0] = self.command
-
-        self.name = '<' + ' '.join(self.args) + '>'
-
-        assert self.pid is None, 'The pid member must be None.'
-        assert self.command is not None, 'The command member must not be None.'
-
-        if self.use_native_pty_fork:
-            try:
-                self.pid, self.child_fd = pty.fork()
-            except OSError:  # pragma: no cover
-                err = sys.exc_info()[1]
-                raise ExceptionPexpect('pty.fork() failed: ' + str(err))
-        else:
-            # Use internal __fork_pty
-            self.pid, self.child_fd = self.__fork_pty()
-
-        # Some platforms must call setwinsize() and setecho() from the
-        # child process, and others from the master process. We do both,
-        # allowing IOError for either.
-
-        if self.pid == pty.CHILD:
-            # Child
-            self.child_fd = self.STDIN_FILENO
-
-            # set default window size of 24 rows by 80 columns
-            try:
-                self.setwinsize(24, 80)
-            except IOError as err:
-                if err.args[0] not in (errno.EINVAL, errno.ENOTTY):
-                    raise
-
-            # disable echo if spawn argument echo was unset
-            if not self.echo:
-                try:
-                    self.setecho(self.echo)
-                except (IOError, termios.error) as err:
-                    if err.args[0] not in (errno.EINVAL, errno.ENOTTY):
-                        raise
-
-            # Do not allow child to inherit open file descriptors from parent.
-            max_fd = resource.getrlimit(resource.RLIMIT_NOFILE)[0]
-            os.closerange(3, max_fd)
-
-            if self.ignore_sighup:
-                signal.signal(signal.SIGHUP, signal.SIG_IGN)
-
-            if self.cwd is not None:
-                os.chdir(self.cwd)
-            if self.env is None:
-                os.execv(self.command, self.args)
-            else:
-                os.execvpe(self.command, self.args, self.env)
-
-        # Parent
-        try:
-            self.setwinsize(24, 80)
-        except IOError as err:
-            if err.args[0] not in (errno.EINVAL, errno.ENOTTY):
-                raise
-
-
-        self.terminated = False
-        self.closed = False
-
-    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("Could not open with os.openpty().")
-
-        pid = os.fork()
-        if pid == pty.CHILD:
-            # Child.
-            os.close(parent_fd)
-            self.__pty_make_controlling_tty(child_fd)
-
-            os.dup2(child_fd, self.STDIN_FILENO)
-            os.dup2(child_fd, self.STDOUT_FILENO)
-            os.dup2(child_fd, self.STDERR_FILENO)
-
-        else:
-            # Parent.
-            os.close(child_fd)
-
-        return pid, parent_fd
-
-    def __pty_make_controlling_tty(self, tty_fd):
-        '''This makes the pseudo-terminal the controlling tty. This should be
-        more portable than the pty.fork() function. Specifically, this should
-        work on Solaris. '''
-
-        child_name = os.ttyname(tty_fd)
-
-        # Disconnect from controlling tty, if any.  Raises OSError of ENXIO
-        # if there was no controlling tty to begin with, such as when
-        # executed by a cron(1) job.
-        try:
-            fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
-            os.close(fd)
-        except OSError as err:
-            if err.errno != errno.ENXIO:
-                raise
-
-        os.setsid()
-
-        # Verify we are disconnected from controlling tty by attempting to open
-        # it again.  We expect that OSError of ENXIO should always be raised.
-        try:
-            fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
-            os.close(fd)
-            raise ExceptionPexpect("OSError of errno.ENXIO should be raised.")
-        except OSError as err:
-            if err.errno != errno.ENXIO:
-                raise
-
-        # Verify we can open child pty.
-        fd = os.open(child_name, os.O_RDWR)
-        os.close(fd)
-
-        # Verify we now have a controlling tty.
-        fd = os.open("/dev/tty", os.O_WRONLY)
-        os.close(fd)
-
-
-    def fileno(self):
-        '''This returns the file descriptor of the pty for the child.
-        '''
-        return self.child_fd
-
-    def close(self, force=True):
-        '''This closes the connection with the child application. Note that
-        calling close() more than once is valid. This emulates standard Python
-        behavior with files. Set force to True if you want to make sure that
-        the child is terminated (SIGKILL is sent if the child ignores SIGHUP
-        and SIGINT). '''
-
-        if not self.closed:
-            self.flush()
-            os.close(self.child_fd)
-            # Give kernel time to update process status.
-            time.sleep(self.delayafterclose)
-            if self.isalive():
-                if not self.terminate(force):
-                    raise ExceptionPexpect('Could not terminate the child.')
-            self.child_fd = -1
-            self.closed = True
-            #self.pid = None
-
-    def flush(self):
-        '''This does nothing. It is here to support the interface for a
-        File-like object. '''
-
-        pass
-
-    def isatty(self):
-        '''This returns True if the file descriptor is open and connected to a
-        tty(-like) device, else False.
-
-        On SVR4-style platforms implementing streams, such as SunOS and HP-UX,
-        the child pty may not appear as a terminal device.  This means
-        methods such as setecho(), setwinsize(), getwinsize() may raise an
-        IOError. '''
-
-        return os.isatty(self.child_fd)
-
-    def waitnoecho(self, timeout=-1):
-        '''This waits until the terminal ECHO flag is set False. This returns
-        True if the echo mode is off. This returns False if the ECHO flag was
-        not set False before the timeout. This can be used to detect when the
-        child is waiting for a password. Usually a child application will turn
-        off echo mode when it is waiting for the user to enter a password. For
-        example, instead of expecting the "password:" prompt you can wait for
-        the child to set ECHO off::
-
-            p = pexpect.spawn('ssh user@example.com')
-            p.waitnoecho()
-            p.sendline(mypassword)
-
-        If timeout==-1 then this method will use the value in self.timeout.
-        If timeout==None then this method to block until ECHO flag is False.
-        '''
-
-        if timeout == -1:
-            timeout = self.timeout
-        if timeout is not None:
-            end_time = time.time() + timeout
-        while True:
-            if not self.getecho():
-                return True
-            if timeout < 0 and timeout is not None:
-                return False
-            if timeout is not None:
-                timeout = end_time - time.time()
-            time.sleep(0.1)
-
-    def getecho(self):
-        '''This returns the terminal echo mode. This returns True if echo is
-        on or False if echo is off. Child applications that are expecting you
-        to enter a password often set ECHO False. See waitnoecho().
-
-        Not supported on platforms where ``isatty()`` returns False.  '''
-
-        try:
-            attr = termios.tcgetattr(self.child_fd)
-        except termios.error as err:
-            errmsg = 'getecho() may not be called on this platform'
-            if err.args[0] == errno.EINVAL:
-                raise IOError(err.args[0], '%s: %s.' % (err.args[1], errmsg))
-            raise
-
-        self.echo = bool(attr[3] & termios.ECHO)
-        return self.echo
-
-    def setecho(self, state):
-        '''This sets the terminal echo mode on or off. Note that anything the
-        child sent before the echo will be lost, so you should be sure that
-        your input buffer is empty before you call setecho(). For example, the
-        following will work as expected::
-
-            p = pexpect.spawn('cat') # Echo is on by default.
-            p.sendline('1234') # We expect see this twice from the child...
-            p.expect(['1234']) # ... once from the tty echo...
-            p.expect(['1234']) # ... and again from cat itself.
-            p.setecho(False) # Turn off tty echo
-            p.sendline('abcd') # We will set this only once (echoed by cat).
-            p.sendline('wxyz') # We will set this only once (echoed by cat)
-            p.expect(['abcd'])
-            p.expect(['wxyz'])
-
-        The following WILL NOT WORK because the lines sent before the setecho
-        will be lost::
-
-            p = pexpect.spawn('cat')
-            p.sendline('1234')
-            p.setecho(False) # Turn off tty echo
-            p.sendline('abcd') # We will set this only once (echoed by cat).
-            p.sendline('wxyz') # We will set this only once (echoed by cat)
-            p.expect(['1234'])
-            p.expect(['1234'])
-            p.expect(['abcd'])
-            p.expect(['wxyz'])
-
-
-        Not supported on platforms where ``isatty()`` returns False.
-        '''
-
-        errmsg = 'setecho() may not be called on this platform'
-
-        try:
-            attr = termios.tcgetattr(self.child_fd)
-        except termios.error as err:
-            if err.args[0] == errno.EINVAL:
-                raise IOError(err.args[0], '%s: %s.' % (err.args[1], errmsg))
-            raise
-
-        if state:
-            attr[3] = attr[3] | termios.ECHO
-        else:
-            attr[3] = attr[3] & ~termios.ECHO
-
-        try:
-            # I tried TCSADRAIN and TCSAFLUSH, but these were inconsistent and
-            # blocked on some platforms. TCSADRAIN would probably be ideal.
-            termios.tcsetattr(self.child_fd, termios.TCSANOW, attr)
-        except IOError as err:
-            if err.args[0] == errno.EINVAL:
-                raise IOError(err.args[0], '%s: %s.' % (err.args[1], errmsg))
-            raise
-
-        self.echo = state
-
-    def _log(self, s, direction):
-        if self.logfile is not None:
-            self.logfile.write(s)
-            self.logfile.flush()
-        second_log = self.logfile_send if (direction=='send') else self.logfile_read
-        if second_log is not None:
-            second_log.write(s)
-            second_log.flush()
-
-    def read_nonblocking(self, size=1, timeout=-1):
-        '''This reads at most size characters from the child application. It
-        includes a timeout. If the read does not complete within the timeout
-        period then a TIMEOUT exception is raised. If the end of file is read
-        then an EOF exception will be raised. If a log file was set using
-        setlog() then all data will also be written to the log file.
-
-        If timeout is None then the read may block indefinitely.
-        If timeout is -1 then the self.timeout value is used. If timeout is 0
-        then the child is polled and if there is no data immediately ready
-        then this will raise a TIMEOUT exception.
-
-        The timeout refers only to the amount of time to read at least one
-        character. This is not effected by the 'size' parameter, so if you call
-        read_nonblocking(size=100, timeout=30) and only one character is
-        available right away then one character will be returned immediately.
-        It will not wait for 30 seconds for another 99 characters to come in.
-
-        This is a wrapper around os.read(). It uses select.select() to
-        implement the timeout. '''
-
-        if self.closed:
-            raise ValueError('I/O operation on closed file.')
-
-        if timeout == -1:
-            timeout = self.timeout
-
-        # Note that some systems such as Solaris do not give an EOF when
-        # the child dies. In fact, you can still try to read
-        # from the child_fd -- it will block forever or until TIMEOUT.
-        # For this case, I test isalive() before doing any reading.
-        # If isalive() is false, then I pretend that this is the same as EOF.
-        if not self.isalive():
-            # timeout of 0 means "poll"
-            r, w, e = self.__select([self.child_fd], [], [], 0)
-            if not r:
-                self.flag_eof = True
-                raise EOF('End Of File (EOF). Braindead platform.')
-        elif self.__irix_hack:
-            # Irix takes a long time before it realizes a child was terminated.
-            # FIXME So does this mean Irix systems are forced to always have
-            # FIXME a 2 second delay when calling read_nonblocking? That sucks.
-            r, w, e = self.__select([self.child_fd], [], [], 2)
-            if not r and not self.isalive():
-                self.flag_eof = True
-                raise EOF('End Of File (EOF). Slow platform.')
-
-        r, w, e = self.__select([self.child_fd], [], [], timeout)
-
-        if not r:
-            if not self.isalive():
-                # Some platforms, such as Irix, will claim that their
-                # processes are alive; timeout on the select; and
-                # then finally admit that they are not alive.
-                self.flag_eof = True
-                raise EOF('End of File (EOF). Very slow platform.')
-            else:
-                raise TIMEOUT('Timeout exceeded.')
-
-        if self.child_fd in r:
-            try:
-                s = os.read(self.child_fd, size)
-            except OSError as err:
-                if err.args[0] == errno.EIO:
-                    # Linux-style EOF
-                    self.flag_eof = True
-                    raise EOF('End Of File (EOF). Exception style platform.')
-                raise
-            if s == b'':
-                # BSD-style EOF
-                self.flag_eof = True
-                raise EOF('End Of File (EOF). Empty string style platform.')
-
-            s = self._coerce_read_string(s)
-            self._log(s, 'read')
-            return s
-
-        raise ExceptionPexpect('Reached an unexpected state.')  # pragma: no cover
-
-    def read(self, size=-1):
-        '''This reads at most "size" bytes from the file (less if the read hits
-        EOF before obtaining size bytes). If the size argument is negative or
-        omitted, read all data until EOF is reached. The bytes are returned as
-        a string object. An empty string is returned when EOF is encountered
-        immediately. '''
-
-        if size == 0:
-            return self.string_type()
-        if size < 0:
-            # delimiter default is EOF
-            self.expect(self.delimiter)
-            return self.before
-
-        # I could have done this more directly by not using expect(), but
-        # I deliberately decided to couple read() to expect() so that
-        # I would catch any bugs early and ensure consistant behavior.
-        # It's a little less efficient, but there is less for me to
-        # worry about if I have to later modify read() or expect().
-        # Note, it's OK if size==-1 in the regex. That just means it
-        # will never match anything in which case we stop only on EOF.
-        cre = re.compile(self._coerce_expect_string('.{%d}' % size), re.DOTALL)
-        # delimiter default is EOF
-        index = self.expect([cre, self.delimiter])
-        if index == 0:
-            ### FIXME self.before should be ''. Should I assert this?
-            return self.after
-        return self.before
-
-    def readline(self, size=-1):
-        '''This reads and returns one entire line. The newline at the end of
-        line is returned as part of the string, unless the file ends without a
-        newline. An empty string is returned if EOF is encountered immediately.
-        This looks for a newline as a CR/LF pair (\\r\\n) even on UNIX because
-        this is what the pseudotty device returns. So contrary to what you may
-        expect you will receive newlines as \\r\\n.
-
-        If the size argument is 0 then an empty string is returned. In all
-        other cases the size argument is ignored, which is not standard
-        behavior for a file-like object. '''
-
-        if size == 0:
-            return self.string_type()
-        # delimiter default is EOF
-        index = self.expect([self.crlf, self.delimiter])
-        if index == 0:
-            return self.before + self.crlf
-        else:
-            return self.before
-
-    def __iter__(self):
-        '''This is to support iterators over a file-like object.
-        '''
-        return iter(self.readline, self.string_type())
-
-    def readlines(self, sizehint=-1):
-        '''This reads until EOF using readline() and returns a list containing
-        the lines thus read. The optional 'sizehint' argument is ignored.
-        Remember, because this reads until EOF that means the child
-        process should have closed its stdout. If you run this method on
-        a child that is still running with its stdout open then this
-        method will block until it timesout.'''
-
-        lines = []
-        while True:
-            line = self.readline()
-            if not line:
-                break
-            lines.append(line)
-        return lines
-
-    def write(self, s):
-        '''This is similar to send() except that there is no return value.
-        '''
-
-        self.send(s)
-
-    def writelines(self, sequence):
-        '''This calls write() for each element in the sequence. The sequence
-        can be any iterable object producing strings, typically a list of
-        strings. This does not add line separators. There is no return value.
-        '''
-
-        for s in sequence:
-            self.write(s)
-
-    def send(self, s):
-        '''Sends string ``s`` to the child process, returning the number of
-        bytes written. If a logfile is specified, a copy is written to that
-        log. '''
-
-        time.sleep(self.delaybeforesend)
-
-        s = self._coerce_send_string(s)
-        self._log(s, 'send')
-
-        return self._send(s)
-
-    def _send(self, s):
-        return os.write(self.child_fd, s)
-
-    def sendline(self, s=''):
-        '''Wraps send(), sending string ``s`` to child process, with os.linesep
-        automatically appended. Returns number of bytes written. '''
-
-        n = self.send(s)
-        n = n + self.send(self.linesep)
-        return n
-
-    def sendcontrol(self, char):
-
-        '''Helper method that wraps send() with mnemonic access for sending control
-        character to the child (such as Ctrl-C or Ctrl-D).  For example, to send
-        Ctrl-G (ASCII 7, bell, '\a')::
-
-            child.sendcontrol('g')
-
-        See also, sendintr() and sendeof().
-        '''
-
-        char = char.lower()
-        a = ord(char)
-        if a >= 97 and a <= 122:
-            a = a - ord('a') + 1
-            return self.send(self._chr(a))
-        d = {'@': 0, '`': 0,
-            '[': 27, '{': 27,
-            '\\': 28, '|': 28,
-            ']': 29, '}': 29,
-            '^': 30, '~': 30,
-            '_': 31,
-            '?': 127}
-        if char not in d:
-            return 0
-        return self.send(self._chr(d[char]))
-
-    def sendeof(self):
-
-        '''This sends an EOF to the child. This sends a character which causes
-        the pending parent output buffer to be sent to the waiting child
-        program without waiting for end-of-line. If it is the first character
-        of the line, the read() in the user program returns 0, which signifies
-        end-of-file. This means to work as expected a sendeof() has to be
-        called at the beginning of a line. This method does not send a newline.
-        It is the responsibility of the caller to ensure the eof is sent at the
-        beginning of a line. '''
-
-        self.send(self._chr(self._EOF))
-
-    def sendintr(self):
-
-        '''This sends a SIGINT to the child. It does not require
-        the SIGINT to be the first character on a line. '''
-
-        self.send(self._chr(self._INTR))
-
-    def eof(self):
-
-        '''This returns True if the EOF exception was ever raised.
-        '''
-
-        return self.flag_eof
-
-    def terminate(self, force=False):
-
-        '''This forces a child process to terminate. It starts nicely with
-        SIGHUP and SIGINT. If "force" is True then moves onto SIGKILL. This
-        returns True if the child was terminated. This returns False if the
-        child could not be terminated. '''
-
-        if not self.isalive():
-            return True
-        try:
-            self.kill(signal.SIGHUP)
-            time.sleep(self.delayafterterminate)
-            if not self.isalive():
-                return True
-            self.kill(signal.SIGCONT)
-            time.sleep(self.delayafterterminate)
-            if not self.isalive():
-                return True
-            self.kill(signal.SIGINT)
-            time.sleep(self.delayafterterminate)
-            if not self.isalive():
-                return True
-            if force:
-                self.kill(signal.SIGKILL)
-                time.sleep(self.delayafterterminate)
-                if not self.isalive():
-                    return True
-                else:
-                    return False
-            return False
-        except OSError:
-            # I think there are kernel timing issues that sometimes cause
-            # this to happen. I think isalive() reports True, but the
-            # process is dead to the kernel.
-            # Make one last attempt to see if the kernel is up to date.
-            time.sleep(self.delayafterterminate)
-            if not self.isalive():
-                return True
-            else:
-                return False
-
-    def wait(self):
-
-        '''This waits until the child exits. This is a blocking call. This will
-        not read any data from the child, so this will block forever if the
-        child has unread output and has terminated. In other words, the child
-        may have printed output then called exit(), but, the child is
-        technically still alive until its output is read by the parent. '''
-
-        if self.isalive():
-            pid, status = os.waitpid(self.pid, 0)
-        else:
-            raise ExceptionPexpect('Cannot wait for dead child process.')
-        self.exitstatus = os.WEXITSTATUS(status)
-        if os.WIFEXITED(status):
-            self.status = status
-            self.exitstatus = os.WEXITSTATUS(status)
-            self.signalstatus = None
-            self.terminated = True
-        elif os.WIFSIGNALED(status):
-            self.status = status
-            self.exitstatus = None
-            self.signalstatus = os.WTERMSIG(status)
-            self.terminated = True
-        elif os.WIFSTOPPED(status):  # pragma: no cover
-            # You can't call wait() on a child process in the stopped state.
-            raise ExceptionPexpect('Called wait() on a stopped child ' +
-                    'process. This is not supported. Is some other ' +
-                    'process attempting job control with our child pid?')
-        return self.exitstatus
-
-    def isalive(self):
-
-        '''This tests if the child process is running or not. This is
-        non-blocking. If the child was terminated then this will read the
-        exitstatus or signalstatus of the child. This returns True if the child
-        process appears to be running or False if not. It can take literally
-        SECONDS for Solaris to return the right status. '''
-
-        if self.terminated:
-            return False
-
-        if self.flag_eof:
-            # This is for Linux, which requires the blocking form
-            # of waitpid to get the status of a defunct process.
-            # This is super-lame. The flag_eof would have been set
-            # in read_nonblocking(), so this should be safe.
-            waitpid_options = 0
-        else:
-            waitpid_options = os.WNOHANG
-
-        try:
-            pid, status = os.waitpid(self.pid, waitpid_options)
-        except OSError:
-            err = sys.exc_info()[1]
-            # No child processes
-            if err.errno == errno.ECHILD:
-                raise ExceptionPexpect('isalive() encountered condition ' +
-                        'where "terminated" is 0, but there was no child ' +
-                        'process. Did someone else call waitpid() ' +
-                        'on our process?')
-            else:
-                raise err
-
-        # I have to do this twice for Solaris.
-        # I can't even believe that I figured this out...
-        # If waitpid() returns 0 it means that no child process
-        # wishes to report, and the value of status is undefined.
-        if pid == 0:
-            try:
-                ### os.WNOHANG) # Solaris!
-                pid, status = os.waitpid(self.pid, waitpid_options)
-            except OSError as e:  # pragma: no cover
-                # This should never happen...
-                if e.errno == errno.ECHILD:
-                    raise ExceptionPexpect('isalive() encountered condition ' +
-                            'that should never happen. There was no child ' +
-                            'process. Did someone else call waitpid() ' +
-                            'on our process?')
-                else:
-                    raise
-
-            # If pid is still 0 after two calls to waitpid() then the process
-            # really is alive. This seems to work on all platforms, except for
-            # Irix which seems to require a blocking call on waitpid or select,
-            # so I let read_nonblocking take care of this situation
-            # (unfortunately, this requires waiting through the timeout).
-            if pid == 0:
-                return True
-
-        if pid == 0:
-            return True
-
-        if os.WIFEXITED(status):
-            self.status = status
-            self.exitstatus = os.WEXITSTATUS(status)
-            self.signalstatus = None
-            self.terminated = True
-        elif os.WIFSIGNALED(status):
-            self.status = status
-            self.exitstatus = None
-            self.signalstatus = os.WTERMSIG(status)
-            self.terminated = True
-        elif os.WIFSTOPPED(status):
-            raise ExceptionPexpect('isalive() encountered condition ' +
-                    'where child process is stopped. This is not ' +
-                    'supported. Is some other process attempting ' +
-                    'job control with our child pid?')
-        return False
-
-    def kill(self, sig):
-
-        '''This sends the given signal to the child application. In keeping
-        with UNIX tradition it has a misleading name. It does not necessarily
-        kill the child unless you send the right signal. '''
-
-        # Same as os.kill, but the pid is given for you.
-        if self.isalive():
-            os.kill(self.pid, sig)
-
-    def _pattern_type_err(self, pattern):
-        raise TypeError('got {badtype} ({badobj!r}) as pattern, must be one'
-                        ' of: {goodtypes}, pexpect.EOF, pexpect.TIMEOUT'\
-                        .format(badtype=type(pattern),
-                                badobj=pattern,
-                                goodtypes=', '.join([str(ast)\
-                                    for ast in self.allowed_string_types])
-                                )
-                        )
-
-    def compile_pattern_list(self, patterns):
-
-        '''This compiles a pattern-string or a list of pattern-strings.
-        Patterns must be a StringType, EOF, TIMEOUT, SRE_Pattern, or a list of
-        those. Patterns may also be None which results in an empty list (you
-        might do this if waiting for an EOF or TIMEOUT condition without
-        expecting any pattern).
-
-        This is used by expect() when calling expect_list(). Thus expect() is
-        nothing more than::
-
-             cpl = self.compile_pattern_list(pl)
-             return self.expect_list(cpl, timeout)
-
-        If you are using expect() within a loop it may be more
-        efficient to compile the patterns first and then call expect_list().
-        This avoid calls in a loop to compile_pattern_list()::
-
-             cpl = self.compile_pattern_list(my_pattern)
-             while some_condition:
-                ...
-                i = self.expect_list(cpl, timeout)
-                ...
-        '''
-
-        if patterns is None:
-            return []
-        if not isinstance(patterns, list):
-            patterns = [patterns]
-
-        # Allow dot to match \n
-        compile_flags = re.DOTALL
-        if self.ignorecase:
-            compile_flags = compile_flags | re.IGNORECASE
-        compiled_pattern_list = []
-        for idx, p in enumerate(patterns):
-            if isinstance(p, self.allowed_string_types):
-                p = self._coerce_expect_string(p)
-                compiled_pattern_list.append(re.compile(p, compile_flags))
-            elif p is EOF:
-                compiled_pattern_list.append(EOF)
-            elif p is TIMEOUT:
-                compiled_pattern_list.append(TIMEOUT)
-            elif isinstance(p, type(re.compile(''))):
-                compiled_pattern_list.append(p)
-            else:
-                self._pattern_type_err(p)
-        return compiled_pattern_list
-
-    def expect(self, pattern, timeout=-1, searchwindowsize=-1, async=False):
-
-        '''This seeks through the stream until a pattern is matched. The
-        pattern is overloaded and may take several types. The pattern can be a
-        StringType, EOF, a compiled re, or a list of any of those types.
-        Strings will be compiled to re types. This returns the index into the
-        pattern list. If the pattern was not a list this returns index 0 on a
-        successful match. This may raise exceptions for EOF or TIMEOUT. To
-        avoid the EOF or TIMEOUT exceptions add EOF or TIMEOUT to the pattern
-        list. That will cause expect to match an EOF or TIMEOUT condition
-        instead of raising an exception.
-
-        If you pass a list of patterns and more than one matches, the first
-        match in the stream is chosen. If more than one pattern matches at that
-        point, the leftmost in the pattern list is chosen. For example::
-
-            # the input is 'foobar'
-            index = p.expect(['bar', 'foo', 'foobar'])
-            # returns 1('foo') even though 'foobar' is a "better" match
-
-        Please note, however, that buffering can affect this behavior, since
-        input arrives in unpredictable chunks. For example::
-
-            # the input is 'foobar'
-            index = p.expect(['foobar', 'foo'])
-            # returns 0('foobar') if all input is available at once,
-            # but returs 1('foo') if parts of the final 'bar' arrive late
-
-        After a match is found the instance attributes 'before', 'after' and
-        'match' will be set. You can see all the data read before the match in
-        'before'. You can see the data that was matched in 'after'. The
-        re.MatchObject used in the re match will be in 'match'. If an error
-        occurred then 'before' will be set to all the data read so far and
-        'after' and 'match' will be None.
-
-        If timeout is -1 then timeout will be set to the self.timeout value.
-
-        A list entry may be EOF or TIMEOUT instead of a string. This will
-        catch these exceptions and return the index of the list entry instead
-        of raising the exception. The attribute 'after' will be set to the
-        exception type. The attribute 'match' will be None. This allows you to
-        write code like this::
-
-                index = p.expect(['good', 'bad', pexpect.EOF, pexpect.TIMEOUT])
-                if index == 0:
-                    do_something()
-                elif index == 1:
-                    do_something_else()
-                elif index == 2:
-                    do_some_other_thing()
-                elif index == 3:
-                    do_something_completely_different()
-
-        instead of code like this::
-
-                try:
-                    index = p.expect(['good', 'bad'])
-                    if index == 0:
-                        do_something()
-                    elif index == 1:
-                        do_something_else()
-                except EOF:
-                    do_some_other_thing()
-                except TIMEOUT:
-                    do_something_completely_different()
-
-        These two forms are equivalent. It all depends on what you want. You
-        can also just expect the EOF if you are waiting for all output of a
-        child to finish. For example::
-
-                p = pexpect.spawn('/bin/ls')
-                p.expect(pexpect.EOF)
-                print p.before
-
-        If you are trying to optimize for speed then see expect_list().
-        
-        On Python 3.4, or Python 3.3 with asyncio installed, passing
-        ``async=True``  will make this return an :mod:`asyncio` coroutine,
-        which you can yield from to get the same result that this method would
-        normally give directly. So, inside a coroutine, you can replace this code::
-        
-            index = p.expect(patterns)
-        
-        With this non-blocking form::
-        
-            index = yield from p.expect(patterns, async=True)
-        '''
-
-        compiled_pattern_list = self.compile_pattern_list(pattern)
-        return self.expect_list(compiled_pattern_list,
-                timeout, searchwindowsize, async)
-
-    def expect_list(self, pattern_list, timeout=-1, searchwindowsize=-1,
-                    async=False):
-        '''This takes a list of compiled regular expressions and returns the
-        index into the pattern_list that matched the child output. The list may
-        also contain EOF or TIMEOUT(which are not compiled regular
-        expressions). This method is similar to the expect() method except that
-        expect_list() does not recompile the pattern list on every call. This
-        may help if you are trying to optimize for speed, otherwise just use
-        the expect() method.  This is called by expect(). If timeout==-1 then
-        the self.timeout value is used. If searchwindowsize==-1 then the
-        self.searchwindowsize value is used.
-
-        Like :meth:`expect`, passing ``async=True`` will make this return an
-        asyncio coroutine.
-        '''
-        if timeout == -1:
-            timeout = self.timeout
-
-        exp = Expecter(self, searcher_re(pattern_list), searchwindowsize)
-        if async:
-            from .async import expect_async
-            return expect_async(exp, timeout)
-        else:
-            return exp.expect_loop(timeout)
-
-    def expect_exact(self, pattern_list, timeout=-1, searchwindowsize=-1,
-                     async=False):
-
-        '''This is similar to expect(), but uses plain string matching instead
-        of compiled regular expressions in 'pattern_list'. The 'pattern_list'
-        may be a string; a list or other sequence of strings; or TIMEOUT and
-        EOF.
-
-        This call might be faster than expect() for two reasons: string
-        searching is faster than RE matching and it is possible to limit the
-        search to just the end of the input buffer.
-
-        This method is also useful when you don't want to have to worry about
-        escaping regular expression characters that you want to match.
-        
-        Like :meth:`expect`, passing ``async=True`` will make this return an
-        asyncio coroutine.
-        '''
-        if timeout == -1:
-            timeout = self.timeout
-
-        if (isinstance(pattern_list, self.allowed_string_types) or
-                pattern_list in (TIMEOUT, EOF)):
-            pattern_list = [pattern_list]
-
-        def prepare_pattern(pattern):
-            if pattern in (TIMEOUT, EOF):
-                return pattern
-            if isinstance(pattern, self.allowed_string_types):
-                return self._coerce_expect_string(pattern)
-            self._pattern_type_err(pattern)
-
-        try:
-            pattern_list = iter(pattern_list)
-        except TypeError:
-            self._pattern_type_err(pattern_list)
-        pattern_list = [prepare_pattern(p) for p in pattern_list]
-
-        exp = Expecter(self, searcher_string(pattern_list), searchwindowsize)
-        if async:
-            from .async import expect_async
-            return expect_async(exp, timeout)
-        else:
-            return exp.expect_loop(timeout)
-
-    def expect_loop(self, searcher, timeout=-1, searchwindowsize=-1):
-        '''This is the common loop used inside expect. The 'searcher' should be
-        an instance of searcher_re or searcher_string, which describes how and
-        what to search for in the input.
-
-        See expect() for other arguments, return value and exceptions. '''
-
-        exp = Expecter(self, searcher, searchwindowsize)
-        return exp.expect_loop(timeout)
-
-    def getwinsize(self):
-
-        '''This returns the terminal window size of the child tty. The return
-        value is a tuple of (rows, cols). '''
-
-        TIOCGWINSZ = getattr(termios, 'TIOCGWINSZ', 1074295912)
-        s = struct.pack('HHHH', 0, 0, 0, 0)
-        x = fcntl.ioctl(self.child_fd, TIOCGWINSZ, s)
-        return struct.unpack('HHHH', x)[0:2]
-
-    def setwinsize(self, rows, cols):
-
-        '''This sets the terminal window size of the child tty. This will cause
-        a SIGWINCH signal to be sent to the child. This does not change the
-        physical window size. It changes the size reported to TTY-aware
-        applications like vi or curses -- applications that respond to the
-        SIGWINCH signal. '''
-
-        # Some very old platforms have a bug that causes the value for
-        # termios.TIOCSWINSZ to be truncated. There was a hack here to work
-        # around this, but it caused problems with newer platforms so has been
-        # removed. For details see https://github.com/pexpect/pexpect/issues/39
-        TIOCSWINSZ = getattr(termios, 'TIOCSWINSZ', -2146929561)
-        # Note, assume ws_xpixel and ws_ypixel are zero.
-        s = struct.pack('HHHH', rows, cols, 0, 0)
-        fcntl.ioctl(self.fileno(), TIOCSWINSZ, s)
-
-    def interact(self, escape_character=chr(29),
-            input_filter=None, output_filter=None):
-
-        '''This gives control of the child process to the interactive user (the
-        human at the keyboard). Keystrokes are sent to the child process, and
-        the stdout and stderr output of the child process is printed. This
-        simply echos the child stdout and child stderr to the real stdout and
-        it echos the real stdin to the child stdin. When the user types the
-        escape_character this method will stop. The default for
-        escape_character is ^]. This should not be confused with ASCII 27 --
-        the ESC character. ASCII 29 was chosen for historical merit because
-        this is the character used by 'telnet' as the escape character. The
-        escape_character will not be sent to the child process.
-
-        You may pass in optional input and output filter functions. These
-        functions should take a string and return a string. The output_filter
-        will be passed all the output from the child process. The input_filter
-        will be passed all the keyboard input from the user. The input_filter
-        is run BEFORE the check for the escape_character.
-
-        Note that if you change the window size of the parent the SIGWINCH
-        signal will not be passed through to the child. If you want the child
-        window size to change when the parent's window size changes then do
-        something like the following example::
-
-            import pexpect, struct, fcntl, termios, signal, sys
-            def sigwinch_passthrough (sig, data):
-                s = struct.pack("HHHH", 0, 0, 0, 0)
-                a = struct.unpack('hhhh', fcntl.ioctl(sys.stdout.fileno(),
-                    termios.TIOCGWINSZ , s))
-                global p
-                p.setwinsize(a[0],a[1])
-            # Note this 'p' global and used in sigwinch_passthrough.
-            p = pexpect.spawn('/bin/bash')
-            signal.signal(signal.SIGWINCH, sigwinch_passthrough)
-            p.interact()
-        '''
-
-        # Flush the buffer.
-        self.write_to_stdout(self.buffer)
-        self.stdout.flush()
-        self.buffer = self.string_type()
-        mode = tty.tcgetattr(self.STDIN_FILENO)
-        tty.setraw(self.STDIN_FILENO)
-        if PY3:
-            escape_character = escape_character.encode('latin-1')
-        try:
-            self.__interact_copy(escape_character, input_filter, output_filter)
-        finally:
-            tty.tcsetattr(self.STDIN_FILENO, tty.TCSAFLUSH, mode)
-
-    def __interact_writen(self, fd, data):
-        '''This is used by the interact() method.
-        '''
-
-        while data != b'' and self.isalive():
-            n = os.write(fd, data)
-            data = data[n:]
-
-    def __interact_read(self, fd):
-        '''This is used by the interact() method.
-        '''
-
-        return os.read(fd, 1000)
-
-    def __interact_copy(self, escape_character=None,
-            input_filter=None, output_filter=None):
-
-        '''This is used by the interact() method.
-        '''
-
-        while self.isalive():
-            r, w, e = self.__select([self.child_fd, self.STDIN_FILENO], [], [])
-            if self.child_fd in r:
-                try:
-                    data = self.__interact_read(self.child_fd)
-                except OSError as err:
-                    if err.args[0] == errno.EIO:
-                        # Linux-style EOF
-                        break
-                    raise
-                if data == b'':
-                    # BSD-style EOF
-                    break
-                if output_filter:
-                    data = output_filter(data)
-                if self.logfile is not None:
-                    self.logfile.write(data)
-                    self.logfile.flush()
-                os.write(self.STDOUT_FILENO, data)
-            if self.STDIN_FILENO in r:
-                data = self.__interact_read(self.STDIN_FILENO)
-                if input_filter:
-                    data = input_filter(data)
-                i = data.rfind(escape_character)
-                if i != -1:
-                    data = data[:i]
-                    self.__interact_writen(self.child_fd, data)
-                    break
-                self.__interact_writen(self.child_fd, data)
-
-    def __select(self, iwtd, owtd, ewtd, timeout=None):
-
-        '''This is a wrapper around select.select() that ignores signals. If
-        select.select raises a select.error exception and errno is an EINTR
-        error then it is ignored. Mainly this is used to ignore sigwinch
-        (terminal resize). '''
-
-        # if select() is interrupted by a signal (errno==EINTR) then
-        # we loop back and enter the select() again.
-        if timeout is not None:
-            end_time = time.time() + timeout
-        while True:
-            try:
-                return select.select(iwtd, owtd, ewtd, timeout)
-            except select.error:
-                err = sys.exc_info()[1]
-                if err.args[0] == errno.EINTR:
-                    # if we loop back we have to subtract the
-                    # amount of time we already waited.
-                    if timeout is not None:
-                        timeout = end_time - time.time()
-                        if timeout < 0:
-                            return([], [], [])
-                else:
-                    # something else caused the select.error, so
-                    # this actually is an exception.
-                    raise
-
-##############################################################################
-# The following methods are no longer supported or allowed.
-
-    def setmaxread(self, maxread): # pragma: no cover
-
-        '''This method is no longer supported or allowed. I don't like getters
-        and setters without a good reason. '''
-
-        raise ExceptionPexpect('This method is no longer supported ' +
-                'or allowed. Just assign a value to the ' +
-                'maxread member variable.')
-
-    def setlog(self, fileobject): # pragma: no cover
-
-        '''This method is no longer supported or allowed.
-        '''
-
-        raise ExceptionPexpect('This method is no longer supported ' +
-                'or allowed. Just assign a value to the logfile ' +
-                'member variable.')
-
-##############################################################################
-# End of spawn class
-##############################################################################
-
-class spawnu(spawn):
-    """Works like spawn, but accepts and returns unicode strings.
-
-    Extra parameters:
-
-    :param encoding: The encoding to use for communications (default: 'utf-8')
-    :param errors: How to handle encoding/decoding errors; one of 'strict'
-                   (the default), 'ignore', or 'replace', as described
-                   for :meth:`~bytes.decode` and :meth:`~str.encode`.
-    """
-    if PY3:
-        string_type = str
-        allowed_string_types = (str, )
-        _chr = staticmethod(chr)
-        linesep = os.linesep
-        crlf = '\r\n'
-    else:
-        string_type = unicode
-        allowed_string_types = (unicode, )
-        _chr = staticmethod(unichr)
-        linesep = os.linesep.decode('ascii')
-        crlf = '\r\n'.decode('ascii')
-    # This can handle unicode in both Python 2 and 3
-    write_to_stdout = sys.stdout.write
-
-    def __init__(self, *args, **kwargs):
-        self.encoding = kwargs.pop('encoding', 'utf-8')
-        self.errors = kwargs.pop('errors', 'strict')
-        self._decoder = codecs.getincrementaldecoder(self.encoding)(errors=self.errors)
-        super(spawnu, self).__init__(*args, **kwargs)
-
-    @staticmethod
-    def _coerce_expect_string(s):
-        return s
-
-    @staticmethod
-    def _coerce_send_string(s):
-        return s
-
-    def _coerce_read_string(self, s):
-        return self._decoder.decode(s, final=False)
-
-    def _send(self, s):
-        return os.write(self.child_fd, s.encode(self.encoding, self.errors))
-
-
-class searcher_string(object):
-
-    '''This is a plain string search helper for the spawn.expect_any() method.
-    This helper class is for speed. For more powerful regex patterns
-    see the helper class, searcher_re.
-
-    Attributes:
-
-        eof_index     - index of EOF, or -1
-        timeout_index - index of TIMEOUT, or -1
-
-    After a successful match by the search() method the following attributes
-    are available:
-
-        start - index into the buffer, first byte of match
-        end   - index into the buffer, first byte after match
-        match - the matching string itself
-
-    '''
-
-    def __init__(self, strings):
-
-        '''This creates an instance of searcher_string. This argument 'strings'
-        may be a list; a sequence of strings; or the EOF or TIMEOUT types. '''
-
-        self.eof_index = -1
-        self.timeout_index = -1
-        self._strings = []
-        for n, s in enumerate(strings):
-            if s is EOF:
-                self.eof_index = n
-                continue
-            if s is TIMEOUT:
-                self.timeout_index = n
-                continue
-            self._strings.append((n, s))
-
-    def __str__(self):
-
-        '''This returns a human-readable string that represents the state of
-        the object.'''
-
-        ss = [(ns[0], '    %d: "%s"' % ns) for ns in self._strings]
-        ss.append((-1, 'searcher_string:'))
-        if self.eof_index >= 0:
-            ss.append((self.eof_index, '    %d: EOF' % self.eof_index))
-        if self.timeout_index >= 0:
-            ss.append((self.timeout_index,
-                '    %d: TIMEOUT' % self.timeout_index))
-        ss.sort()
-        ss = list(zip(*ss))[1]
-        return '\n'.join(ss)
-
-    def search(self, buffer, freshlen, searchwindowsize=None):
-
-        '''This searches 'buffer' for the first occurence of one of the search
-        strings.  'freshlen' must indicate the number of bytes at the end of
-        'buffer' which have not been searched before. It helps to avoid
-        searching the same, possibly big, buffer over and over again.
-
-        See class spawn for the 'searchwindowsize' argument.
-
-        If there is a match this returns the index of that string, and sets
-        'start', 'end' and 'match'. Otherwise, this returns -1. '''
-
-        first_match = None
-
-        # 'freshlen' helps a lot here. Further optimizations could
-        # possibly include:
-        #
-        # using something like the Boyer-Moore Fast String Searching
-        # Algorithm; pre-compiling the search through a list of
-        # strings into something that can scan the input once to
-        # search for all N strings; realize that if we search for
-        # ['bar', 'baz'] and the input is '...foo' we need not bother
-        # rescanning until we've read three more bytes.
-        #
-        # Sadly, I don't know enough about this interesting topic. /grahn
-
-        for index, s in self._strings:
-            if searchwindowsize is None:
-                # the match, if any, can only be in the fresh data,
-                # or at the very end of the old data
-                offset = -(freshlen + len(s))
-            else:
-                # better obey searchwindowsize
-                offset = -searchwindowsize
-            n = buffer.find(s, offset)
-            if n >= 0 and (first_match is None or n < first_match):
-                first_match = n
-                best_index, best_match = index, s
-        if first_match is None:
-            return -1
-        self.match = best_match
-        self.start = first_match
-        self.end = self.start + len(self.match)
-        return best_index
-
-
-class searcher_re(object):
-
-    '''This is regular expression string search helper for the
-    spawn.expect_any() method. This helper class is for powerful
-    pattern matching. For speed, see the helper class, searcher_string.
-
-    Attributes:
-
-        eof_index     - index of EOF, or -1
-        timeout_index - index of TIMEOUT, or -1
-
-    After a successful match by the search() method the following attributes
-    are available:
-
-        start - index into the buffer, first byte of match
-        end   - index into the buffer, first byte after match
-        match - the re.match object returned by a succesful re.search
-
-    '''
-
-    def __init__(self, patterns):
-
-        '''This creates an instance that searches for 'patterns' Where
-        'patterns' may be a list or other sequence of compiled regular
-        expressions, or the EOF or TIMEOUT types.'''
-
-        self.eof_index = -1
-        self.timeout_index = -1
-        self._searches = []
-        for n, s in zip(list(range(len(patterns))), patterns):
-            if s is EOF:
-                self.eof_index = n
-                continue
-            if s is TIMEOUT:
-                self.timeout_index = n
-                continue
-            self._searches.append((n, s))
-
-    def __str__(self):
-
-        '''This returns a human-readable string that represents the state of
-        the object.'''
-
-        #ss = [(n, '    %d: re.compile("%s")' %
-        #    (n, repr(s.pattern))) for n, s in self._searches]
-        ss = list()
-        for n, s in self._searches:
-            try:
-                ss.append((n, '    %d: re.compile("%s")' % (n, s.pattern)))
-            except UnicodeEncodeError:
-                # for test cases that display __str__ of searches, dont throw
-                # another exception just because stdout is ascii-only, using
-                # repr()
-                ss.append((n, '    %d: re.compile(%r)' % (n, s.pattern)))
-        ss.append((-1, 'searcher_re:'))
-        if self.eof_index >= 0:
-            ss.append((self.eof_index, '    %d: EOF' % self.eof_index))
-        if self.timeout_index >= 0:
-            ss.append((self.timeout_index, '    %d: TIMEOUT' %
-                self.timeout_index))
-        ss.sort()
-        ss = list(zip(*ss))[1]
-        return '\n'.join(ss)
-
-    def search(self, buffer, freshlen, searchwindowsize=None):
-
-        '''This searches 'buffer' for the first occurence of one of the regular
-        expressions. 'freshlen' must indicate the number of bytes at the end of
-        'buffer' which have not been searched before.
-
-        See class spawn for the 'searchwindowsize' argument.
-
-        If there is a match this returns the index of that string, and sets
-        'start', 'end' and 'match'. Otherwise, returns -1.'''
-
-        first_match = None
-        # 'freshlen' doesn't help here -- we cannot predict the
-        # length of a match, and the re module provides no help.
-        if searchwindowsize is None:
-            searchstart = 0
-        else:
-            searchstart = max(0, len(buffer) - searchwindowsize)
-        for index, s in self._searches:
-            match = s.search(buffer, searchstart)
-            if match is None:
-                continue
-            n = match.start()
-            if first_match is None or n < first_match:
-                first_match = n
-                the_match = match
-                best_index = index
-        if first_match is None:
-            return -1
-        self.start = first_match
-        self.match = the_match
-        self.end = self.match.end()
-        return best_index
-
-
-def is_executable_file(path):
-    """Checks that path is an executable regular file, or a symlink to one.
-
-    This is roughly ``os.path isfile(path) and os.access(path, os.X_OK)``,
-    except for root users, which are permitted to execute a file only if
-    any of the execute bits are set.
-    """
-    # follow symlinks,
-    fpath = os.path.realpath(path)
-
-    if not os.path.isfile(fpath):
-        # non-files (directories, fifo, etc.)
-        return False
-
-    mode = os.stat(fpath).st_mode
-
-    if os.getuid() == 0:
-        # when root, any permission bit of any section
-        # is fine, even if we do not own the file.
-        return bool(mode & (stat.S_IXUSR |
-                            stat.S_IXGRP |
-                            stat.S_IXOTH))
-
-    return os.access(fpath, os.X_OK)
-
-
-def which(filename):
-    '''This takes a given filename; tries to find it in the environment path;
-    then checks if it is executable. This returns the full path to the filename
-    if found and executable. Otherwise this returns None.'''
-
-    # Special case where filename contains an explicit path.
-    if os.path.dirname(filename) != '' and is_executable_file(filename):
-        return filename
-    if 'PATH' not in os.environ or os.environ['PATH'] == '':
-        p = os.defpath
-    else:
-        p = os.environ['PATH']
-    pathlist = p.split(os.pathsep)
-    for path in pathlist:
-        ff = os.path.join(path, filename)
-        if is_executable_file(ff):
-            return ff
-    return None
-
-
-def split_command_line(command_line):
-
-    '''This splits a command line into a list of arguments. It splits arguments
-    on spaces, but handles embedded quotes, doublequotes, and escaped
-    characters. It's impossible to do this with a regular expression, so I
-    wrote a little state machine to parse the command line. '''
-
-    arg_list = []
-    arg = ''
-
-    # Constants to name the states we can be in.
-    state_basic = 0
-    state_esc = 1
-    state_singlequote = 2
-    state_doublequote = 3
-    # The state when consuming whitespace between commands.
-    state_whitespace = 4
-    state = state_basic
-
-    for c in command_line:
-        if state == state_basic or state == state_whitespace:
-            if c == '\\':
-                # Escape the next character
-                state = state_esc
-            elif c == r"'":
-                # Handle single quote
-                state = state_singlequote
-            elif c == r'"':
-                # Handle double quote
-                state = state_doublequote
-            elif c.isspace():
-                # Add arg to arg_list if we aren't in the middle of whitespace.
-                if state == state_whitespace:
-                    # Do nothing.
-                    None
-                else:
-                    arg_list.append(arg)
-                    arg = ''
-                    state = state_whitespace
-            else:
-                arg = arg + c
-                state = state_basic
-        elif state == state_esc:
-            arg = arg + c
-            state = state_basic
-        elif state == state_singlequote:
-            if c == r"'":
-                state = state_basic
-            else:
-                arg = arg + c
-        elif state == state_doublequote:
-            if c == r'"':
-                state = state_basic
-            else:
-                arg = arg + c
-
-    if arg != '':
-        arg_list.append(arg)
-    return arg_list
-
 # vim: set shiftround expandtab tabstop=4 shiftwidth=4 ft=python autoindent :
diff --git a/pexpect/async.py b/pexpect/async.py
index 8ec9c3c..50eae3b 100644
--- a/pexpect/async.py
+++ b/pexpect/async.py
@@ -53,6 +53,8 @@ class PatternWaiter(asyncio.Protocol):
             self.error(e)
     
     def eof_received(self):
+        # N.B. If this gets called, async will close the pipe (the spawn object)
+        # for us
         try:
             index = self.expecter.eof()
         except EOF as e:
diff --git a/pexpect/exceptions.py b/pexpect/exceptions.py
new file mode 100644
index 0000000..cb360f0
--- /dev/null
+++ b/pexpect/exceptions.py
@@ -0,0 +1,35 @@
+"""Exception classes used by Pexpect"""
+
+import traceback
+import sys
+
+class ExceptionPexpect(Exception):
+    '''Base class for all exceptions raised by this module.
+    '''
+
+    def __init__(self, value):
+        super(ExceptionPexpect, self).__init__(value)
+        self.value = value
+
+    def __str__(self):
+        return str(self.value)
+
+    def get_trace(self):
+        '''This returns an abbreviated stack trace with lines that only concern
+        the caller. In other words, the stack trace inside the Pexpect module
+        is not included. '''
+
+        tblist = traceback.extract_tb(sys.exc_info()[2])
+        tblist = [item for item in tblist if ('pexpect/__init__' not in item[0])
+                                           and ('pexpect/expect' not in item[0])]
+        tblist = traceback.format_list(tblist)
+        return ''.join(tblist)
+
+
+class EOF(ExceptionPexpect):
+    '''Raised when EOF is read from a child.
+    This usually means the child has exited.'''
+
+
+class TIMEOUT(ExceptionPexpect):
+    '''Raised when a read time exceeds the timeout. '''
diff --git a/pexpect/expect.py b/pexpect/expect.py
index b8da406..6fde9e8 100644
--- a/pexpect/expect.py
+++ b/pexpect/expect.py
@@ -1,5 +1,7 @@
 import time
 
+from .exceptions import EOF, TIMEOUT
+
 class Expecter(object):
     def __init__(self, spawn, searcher, searchwindowsize=-1):
         self.spawn = spawn
@@ -102,4 +104,194 @@ class Expecter(object):
             return self.timeout(e)
         except:
             self.errored()
-            raise
\ No newline at end of file
+            raise
+
+
+class searcher_string(object):
+    '''This is a plain string search helper for the spawn.expect_any() method.
+    This helper class is for speed. For more powerful regex patterns
+    see the helper class, searcher_re.
+
+    Attributes:
+
+        eof_index     - index of EOF, or -1
+        timeout_index - index of TIMEOUT, or -1
+
+    After a successful match by the search() method the following attributes
+    are available:
+
+        start - index into the buffer, first byte of match
+        end   - index into the buffer, first byte after match
+        match - the matching string itself
+
+    '''
+
+    def __init__(self, strings):
+        '''This creates an instance of searcher_string. This argument 'strings'
+        may be a list; a sequence of strings; or the EOF or TIMEOUT types. '''
+
+        self.eof_index = -1
+        self.timeout_index = -1
+        self._strings = []
+        for n, s in enumerate(strings):
+            if s is EOF:
+                self.eof_index = n
+                continue
+            if s is TIMEOUT:
+                self.timeout_index = n
+                continue
+            self._strings.append((n, s))
+
+    def __str__(self):
+        '''This returns a human-readable string that represents the state of
+        the object.'''
+
+        ss = [(ns[0], '    %d: "%s"' % ns) for ns in self._strings]
+        ss.append((-1, 'searcher_string:'))
+        if self.eof_index >= 0:
+            ss.append((self.eof_index, '    %d: EOF' % self.eof_index))
+        if self.timeout_index >= 0:
+            ss.append((self.timeout_index,
+                '    %d: TIMEOUT' % self.timeout_index))
+        ss.sort()
+        ss = list(zip(*ss))[1]
+        return '\n'.join(ss)
+
+    def search(self, buffer, freshlen, searchwindowsize=None):
+        '''This searches 'buffer' for the first occurence of one of the search
+        strings.  'freshlen' must indicate the number of bytes at the end of
+        'buffer' which have not been searched before. It helps to avoid
+        searching the same, possibly big, buffer over and over again.
+
+        See class spawn for the 'searchwindowsize' argument.
+
+        If there is a match this returns the index of that string, and sets
+        'start', 'end' and 'match'. Otherwise, this returns -1. '''
+
+        first_match = None
+
+        # 'freshlen' helps a lot here. Further optimizations could
+        # possibly include:
+        #
+        # using something like the Boyer-Moore Fast String Searching
+        # Algorithm; pre-compiling the search through a list of
+        # strings into something that can scan the input once to
+        # search for all N strings; realize that if we search for
+        # ['bar', 'baz'] and the input is '...foo' we need not bother
+        # rescanning until we've read three more bytes.
+        #
+        # Sadly, I don't know enough about this interesting topic. /grahn
+
+        for index, s in self._strings:
+            if searchwindowsize is None:
+                # the match, if any, can only be in the fresh data,
+                # or at the very end of the old data
+                offset = -(freshlen + len(s))
+            else:
+                # better obey searchwindowsize
+                offset = -searchwindowsize
+            n = buffer.find(s, offset)
+            if n >= 0 and (first_match is None or n < first_match):
+                first_match = n
+                best_index, best_match = index, s
+        if first_match is None:
+            return -1
+        self.match = best_match
+        self.start = first_match
+        self.end = self.start + len(self.match)
+        return best_index
+
+
+class searcher_re(object):
+    '''This is regular expression string search helper for the
+    spawn.expect_any() method. This helper class is for powerful
+    pattern matching. For speed, see the helper class, searcher_string.
+
+    Attributes:
+
+        eof_index     - index of EOF, or -1
+        timeout_index - index of TIMEOUT, or -1
+
+    After a successful match by the search() method the following attributes
+    are available:
+
+        start - index into the buffer, first byte of match
+        end   - index into the buffer, first byte after match
+        match - the re.match object returned by a succesful re.search
+
+    '''
+
+    def __init__(self, patterns):
+        '''This creates an instance that searches for 'patterns' Where
+        'patterns' may be a list or other sequence of compiled regular
+        expressions, or the EOF or TIMEOUT types.'''
+
+        self.eof_index = -1
+        self.timeout_index = -1
+        self._searches = []
+        for n, s in zip(list(range(len(patterns))), patterns):
+            if s is EOF:
+                self.eof_index = n
+                continue
+            if s is TIMEOUT:
+                self.timeout_index = n
+                continue
+            self._searches.append((n, s))
+
+    def __str__(self):
+        '''This returns a human-readable string that represents the state of
+        the object.'''
+
+        #ss = [(n, '    %d: re.compile("%s")' %
+        #    (n, repr(s.pattern))) for n, s in self._searches]
+        ss = list()
+        for n, s in self._searches:
+            try:
+                ss.append((n, '    %d: re.compile("%s")' % (n, s.pattern)))
+            except UnicodeEncodeError:
+                # for test cases that display __str__ of searches, dont throw
+                # another exception just because stdout is ascii-only, using
+                # repr()
+                ss.append((n, '    %d: re.compile(%r)' % (n, s.pattern)))
+        ss.append((-1, 'searcher_re:'))
+        if self.eof_index >= 0:
+            ss.append((self.eof_index, '    %d: EOF' % self.eof_index))
+        if self.timeout_index >= 0:
+            ss.append((self.timeout_index, '    %d: TIMEOUT' %
+                self.timeout_index))
+        ss.sort()
+        ss = list(zip(*ss))[1]
+        return '\n'.join(ss)
+
+    def search(self, buffer, freshlen, searchwindowsize=None):
+        '''This searches 'buffer' for the first occurence of one of the regular
+        expressions. 'freshlen' must indicate the number of bytes at the end of
+        'buffer' which have not been searched before.
+
+        See class spawn for the 'searchwindowsize' argument.
+
+        If there is a match this returns the index of that string, and sets
+        'start', 'end' and 'match'. Otherwise, returns -1.'''
+
+        first_match = None
+        # 'freshlen' doesn't help here -- we cannot predict the
+        # length of a match, and the re module provides no help.
+        if searchwindowsize is None:
+            searchstart = 0
+        else:
+            searchstart = max(0, len(buffer) - searchwindowsize)
+        for index, s in self._searches:
+            match = s.search(buffer, searchstart)
+            if match is None:
+                continue
+            n = match.start()
+            if first_match is None or n < first_match:
+                first_match = n
+                the_match = match
+                best_index = index
+        if first_match is None:
+            return -1
+        self.start = first_match
+        self.match = the_match
+        self.end = self.match.end()
+        return best_index
\ No newline at end of file
diff --git a/pexpect/fdpexpect.py b/pexpect/fdpexpect.py
index fe4ad89..96ca2e1 100644
--- a/pexpect/fdpexpect.py
+++ b/pexpect/fdpexpect.py
@@ -21,26 +21,22 @@ PEXPECT LICENSE
 
 '''
 
-from pexpect import spawn, ExceptionPexpect
+from .spawnbase import SpawnBase
+from .exceptions import ExceptionPexpect
 import os
 
 __all__ = ['fdspawn']
 
-class fdspawn (spawn):
-
+class fdspawn(SpawnBase):
     '''This is like pexpect.spawn but allows you to supply your own open file
     descriptor. For example, you could use it to read through a file looking
     for patterns, or to control a modem or serial device. '''
 
-    def __init__ (self, fd, args=[], timeout=30, maxread=2000, searchwindowsize=None, logfile=None):
-
+    def __init__ (self, fd, args=None, timeout=30, maxread=2000, searchwindowsize=None, logfile=None):
         '''This takes a file descriptor (an int) or an object that support the
         fileno() method (returning an int). All Python file-like objects
         support fileno(). '''
 
-        ### TODO: Add better handling of trying to use fdspawn in place of spawn
-        ### TODO: (overload to allow fdspawn to also handle commands as spawn does.
-
         if type(fd) != type(0) and hasattr(fd, 'fileno'):
             fd = fd.fileno()
 
@@ -54,15 +50,12 @@ class fdspawn (spawn):
 
         self.args = None
         self.command = None
-        spawn.__init__(self, None, args, timeout, maxread, searchwindowsize, logfile)
+        SpawnBase.__init__(self, timeout, maxread, searchwindowsize, logfile)
         self.child_fd = fd
         self.own_fd = False
         self.closed = False
         self.name = '<file descriptor %d>' % fd
 
-    def __del__ (self):
-        return
-
     def close (self):
         """Close the file descriptor.
 
@@ -91,7 +84,3 @@ class fdspawn (spawn):
 
     def terminate (self, force=False):  # pragma: no cover
         raise ExceptionPexpect('This method is not valid for file descriptors.')
-
-    def kill (self, sig):  # pragma: no cover
-        """No-op - no process to kill."""
-        return
diff --git a/pexpect/pty_spawn.py b/pexpect/pty_spawn.py
new file mode 100644
index 0000000..b3fbeca
--- /dev/null
+++ b/pexpect/pty_spawn.py
@@ -0,0 +1,809 @@
+import os
+import sys
+import time
+import select
+import re
+import pty
+import tty
+import termios
+import errno
+import signal
+from contextlib import contextmanager
+
+import ptyprocess
+from ptyprocess.ptyprocess import use_native_pty_fork
+
+from .exceptions import ExceptionPexpect, EOF, TIMEOUT
+from .spawnbase import SpawnBase, SpawnBaseUnicode
+from .utils import which, split_command_line
+
+@contextmanager
+def _wrap_ptyprocess_err():
+    """Turn ptyprocess errors into our own ExceptionPexpect errors"""
+    try:
+        yield
+    except ptyprocess.PtyProcessError as e:
+        raise ExceptionPexpect(*e.args)
+
+PY3 = (sys.version_info[0] >= 3)
+
+class spawn(SpawnBase):
+    '''This is the main class interface for Pexpect. Use this class to start
+    and control child applications. '''
+    ptyprocess_class = ptyprocess.PtyProcess
+
+    # This is purely informational now - changing it has no effect
+    use_native_pty_fork = use_native_pty_fork
+
+    def __init__(self, command, args=[], timeout=30, maxread=2000,
+                 searchwindowsize=None, logfile=None, cwd=None, env=None,
+                 ignore_sighup=True, echo=True):
+        '''This is the constructor. The command parameter may be a string that
+        includes a command and any arguments to the command. For example::
+
+            child = pexpect.spawn('/usr/bin/ftp')
+            child = pexpect.spawn('/usr/bin/ssh user@example.com')
+            child = pexpect.spawn('ls -latr /tmp')
+
+        You may also construct it with a list of arguments like so::
+
+            child = pexpect.spawn('/usr/bin/ftp', [])
+            child = pexpect.spawn('/usr/bin/ssh', ['user@example.com'])
+            child = pexpect.spawn('ls', ['-latr', '/tmp'])
+
+        After this the child application will be created and will be ready to
+        talk to. For normal use, see expect() and send() and sendline().
+
+        Remember that Pexpect does NOT interpret shell meta characters such as
+        redirect, pipe, or wild cards (``>``, ``|``, or ``*``). This is a
+        common mistake.  If you want to run a command and pipe it through
+        another command then you must also start a shell. For example::
+
+            child = pexpect.spawn('/bin/bash -c "ls -l | grep LOG > logs.txt"')
+            child.expect(pexpect.EOF)
+
+        The second form of spawn (where you pass a list of arguments) is useful
+        in situations where you wish to spawn a command and pass it its own
+        argument list. This can make syntax more clear. For example, the
+        following is equivalent to the previous example::
+
+            shell_cmd = 'ls -l | grep LOG > logs.txt'
+            child = pexpect.spawn('/bin/bash', ['-c', shell_cmd])
+            child.expect(pexpect.EOF)
+
+        The maxread attribute sets the read buffer size. This is maximum number
+        of bytes that Pexpect will try to read from a TTY at one time. Setting
+        the maxread size to 1 will turn off buffering. Setting the maxread
+        value higher may help performance in cases where large amounts of
+        output are read back from the child. This feature is useful in
+        conjunction with searchwindowsize.
+
+        The searchwindowsize attribute sets the how far back in the incoming
+        seach buffer Pexpect will search for pattern matches. Every time
+        Pexpect reads some data from the child it will append the data to the
+        incoming buffer. The default is to search from the beginning of the
+        incoming buffer each time new data is read from the child. But this is
+        very inefficient if you are running a command that generates a large
+        amount of data where you want to match. The searchwindowsize does not
+        affect the size of the incoming data buffer. You will still have
+        access to the full buffer after expect() returns.
+
+        The logfile member turns on or off logging. All input and output will
+        be copied to the given file object. Set logfile to None to stop
+        logging. This is the default. Set logfile to sys.stdout to echo
+        everything to standard output. The logfile is flushed after each write.
+
+        Example log input and output to a file::
+
+            child = pexpect.spawn('some_command')
+            fout = open('mylog.txt','wb')
+            child.logfile = fout
+
+        Example log to stdout::
+
+            # In Python 2:
+            child = pexpect.spawn('some_command')
+            child.logfile = sys.stdout
+
+            # In Python 3, spawnu should be used to give str to stdout:
+            child = pexpect.spawnu('some_command')
+            child.logfile = sys.stdout
+
+        The logfile_read and logfile_send members can be used to separately log
+        the input from the child and output sent to the child. Sometimes you
+        don't want to see everything you write to the child. You only want to
+        log what the child sends back. For example::
+
+            child = pexpect.spawn('some_command')
+            child.logfile_read = sys.stdout
+
+        Remember to use spawnu instead of spawn for the above code if you are
+        using Python 3.
+
+        To separately log output sent to the child use logfile_send::
+
+            child.logfile_send = fout
+
+        If ``ignore_sighup`` is True, the child process will ignore SIGHUP
+        signals. For now, the default is True, to preserve the behaviour of
+        earlier versions of Pexpect, but you should pass this explicitly if you
+        want to rely on it.
+
+        The delaybeforesend helps overcome a weird behavior that many users
+        were experiencing. The typical problem was that a user would expect() a
+        "Password:" prompt and then immediately call sendline() to send the
+        password. The user would then see that their password was echoed back
+        to them. Passwords don't normally echo. The problem is caused by the
+        fact that most applications print out the "Password" prompt and then
+        turn off stdin echo, but if you send your password before the
+        application turned off echo, then you get your password echoed.
+        Normally this wouldn't be a problem when interacting with a human at a
+        real keyboard. If you introduce a slight delay just before writing then
+        this seems to clear up the problem. This was such a common problem for
+        many users that I decided that the default pexpect behavior should be
+        to sleep just before writing to the child application. 1/20th of a
+        second (50 ms) seems to be enough to clear up the problem. You can set
+        delaybeforesend to 0 to return to the old behavior. Most Linux machines
+        don't like this to be below 0.03. I don't know why.
+
+        Note that spawn is clever about finding commands on your path.
+        It uses the same logic that "which" uses to find executables.
+
+        If you wish to get the exit status of the child you must call the
+        close() method. The exit or signal status of the child will be stored
+        in self.exitstatus or self.signalstatus. If the child exited normally
+        then exitstatus will store the exit return code and signalstatus will
+        be None. If the child was terminated abnormally with a signal then
+        signalstatus will store the signal value and exitstatus will be None.
+        If you need more detail you can also read the self.status member which
+        stores the status returned by os.waitpid. You can interpret this using
+        os.WIFEXITED/os.WEXITSTATUS or os.WIFSIGNALED/os.TERMSIG.
+
+        The echo attribute may be set to False to disable echoing of input.
+        As a pseudo-terminal, all input echoed by the "keyboard" (send()
+        or sendline()) will be repeated to output.  For many cases, it is
+        not desirable to have echo enabled, and it may be later disabled
+        using setecho(False) followed by waitnoecho().  However, for some
+        platforms such as Solaris, this is not possible, and should be
+        disabled immediately on spawn.
+        '''
+        super(spawn, self).__init__(timeout=timeout, maxread=maxread, searchwindowsize=searchwindowsize,
+                                    logfile=logfile)
+        self.STDIN_FILENO = pty.STDIN_FILENO
+        self.STDOUT_FILENO = pty.STDOUT_FILENO
+        self.STDERR_FILENO = pty.STDERR_FILENO
+        self.cwd = cwd
+        self.env = env
+        self.echo = echo
+        self.ignore_sighup = ignore_sighup
+        self.__irix_hack = sys.platform.lower().startswith('irix')
+        if command is None:
+            self.command = None
+            self.args = None
+            self.name = '<pexpect factory incomplete>'
+        else:
+            self._spawn(command, args)
+
+    def __str__(self):
+        '''This returns a human-readable string that represents the state of
+        the object. '''
+
+        s = []
+        s.append(repr(self))
+        s.append('command: ' + str(self.command))
+        s.append('args: %r' % (self.args,))
+        s.append('searcher: %r' % (self.searcher,))
+        s.append('buffer (last 100 chars): %r' % (
+                self.buffer[-100:] if self.buffer else self.buffer,))
+        s.append('before (last 100 chars): %r' % (
+                self.before[-100:] if self.before else self.before,))
+        s.append('after: %r' % (self.after,))
+        s.append('match: %r' % (self.match,))
+        s.append('match_index: ' + str(self.match_index))
+        s.append('exitstatus: ' + str(self.exitstatus))
+        s.append('flag_eof: ' + str(self.flag_eof))
+        s.append('pid: ' + str(self.pid))
+        s.append('child_fd: ' + str(self.child_fd))
+        s.append('closed: ' + str(self.closed))
+        s.append('timeout: ' + str(self.timeout))
+        s.append('delimiter: ' + str(self.delimiter))
+        s.append('logfile: ' + str(self.logfile))
+        s.append('logfile_read: ' + str(self.logfile_read))
+        s.append('logfile_send: ' + str(self.logfile_send))
+        s.append('maxread: ' + str(self.maxread))
+        s.append('ignorecase: ' + str(self.ignorecase))
+        s.append('searchwindowsize: ' + str(self.searchwindowsize))
+        s.append('delaybeforesend: ' + str(self.delaybeforesend))
+        s.append('delayafterclose: ' + str(self.delayafterclose))
+        s.append('delayafterterminate: ' + str(self.delayafterterminate))
+        return '\n'.join(s)
+
+    def _spawn(self, command, args=[]):
+        '''This starts the given command in a child process. This does all the
+        fork/exec type of stuff for a pty. This is called by __init__. If args
+        is empty then command will be parsed (split on spaces) and args will be
+        set to parsed arguments. '''
+
+        # The pid and child_fd of this object get set by this method.
+        # Note that it is difficult for this method to fail.
+        # You cannot detect if the child process cannot start.
+        # So the only way you can tell if the child process started
+        # or not is to try to read from the file descriptor. If you get
+        # EOF immediately then it means that the child is already dead.
+        # That may not necessarily be bad because you may have spawned a child
+        # that performs some task; creates no stdout output; and then dies.
+
+        # If command is an int type then it may represent a file descriptor.
+        if isinstance(command, type(0)):
+            raise ExceptionPexpect('Command is an int type. ' +
+                    'If this is a file descriptor then maybe you want to ' +
+                    'use fdpexpect.fdspawn which takes an existing ' +
+                    'file descriptor instead of a command string.')
+
+        if not isinstance(args, type([])):
+            raise TypeError('The argument, args, must be a list.')
+
+        if args == []:
+            self.args = split_command_line(command)
+            self.command = self.args[0]
+        else:
+            # Make a shallow copy of the args list.
+            self.args = args[:]
+            self.args.insert(0, command)
+            self.command = command
+
+        command_with_path = which(self.command)
+        if command_with_path is None:
+            raise ExceptionPexpect('The command was not found or was not ' +
+                    'executable: %s.' % self.command)
+        self.command = command_with_path
+        self.args[0] = self.command
+
+        self.name = '<' + ' '.join(self.args) + '>'
+
+        assert self.pid is None, 'The pid member must be None.'
+        assert self.command is not None, 'The command member must not be None.'
+
+        kwargs = {'echo': self.echo}
+        if self.ignore_sighup:
+            kwargs['before_exec'] = [lambda: signal.signal(signal.SIGHUP, signal.SIG_IGN)]
+        self.ptyproc = self.ptyprocess_class.spawn(self.args, env=self.env,
+                                                   cwd=self.cwd, **kwargs)
+
+        self.pid = self.ptyproc.pid
+        self.child_fd = self.ptyproc.fd
+
+
+        self.terminated = False
+        self.closed = False
+
+    def close(self, force=True):
+        '''This closes the connection with the child application. Note that
+        calling close() more than once is valid. This emulates standard Python
+        behavior with files. Set force to True if you want to make sure that
+        the child is terminated (SIGKILL is sent if the child ignores SIGHUP
+        and SIGINT). '''
+
+        self.flush()
+        self.ptyproc.close()
+        self.isalive()  # Update exit status from ptyproc
+        self.child_fd = -1
+
+    def isatty(self):
+        '''This returns True if the file descriptor is open and connected to a
+        tty(-like) device, else False.
+
+        On SVR4-style platforms implementing streams, such as SunOS and HP-UX,
+        the child pty may not appear as a terminal device.  This means
+        methods such as setecho(), setwinsize(), getwinsize() may raise an
+        IOError. '''
+
+        return os.isatty(self.child_fd)
+
+    def waitnoecho(self, timeout=-1):
+        '''This waits until the terminal ECHO flag is set False. This returns
+        True if the echo mode is off. This returns False if the ECHO flag was
+        not set False before the timeout. This can be used to detect when the
+        child is waiting for a password. Usually a child application will turn
+        off echo mode when it is waiting for the user to enter a password. For
+        example, instead of expecting the "password:" prompt you can wait for
+        the child to set ECHO off::
+
+            p = pexpect.spawn('ssh user@example.com')
+            p.waitnoecho()
+            p.sendline(mypassword)
+
+        If timeout==-1 then this method will use the value in self.timeout.
+        If timeout==None then this method to block until ECHO flag is False.
+        '''
+
+        if timeout == -1:
+            timeout = self.timeout
+        if timeout is not None:
+            end_time = time.time() + timeout
+        while True:
+            if not self.getecho():
+                return True
+            if timeout < 0 and timeout is not None:
+                return False
+            if timeout is not None:
+                timeout = end_time - time.time()
+            time.sleep(0.1)
+
+    def getecho(self):
+        '''This returns the terminal echo mode. This returns True if echo is
+        on or False if echo is off. Child applications that are expecting you
+        to enter a password often set ECHO False. See waitnoecho().
+
+        Not supported on platforms where ``isatty()`` returns False.  '''
+        return self.ptyproc.getecho()
+
+    def setecho(self, state):
+        '''This sets the terminal echo mode on or off. Note that anything the
+        child sent before the echo will be lost, so you should be sure that
+        your input buffer is empty before you call setecho(). For example, the
+        following will work as expected::
+
+            p = pexpect.spawn('cat') # Echo is on by default.
+            p.sendline('1234') # We expect see this twice from the child...
+            p.expect(['1234']) # ... once from the tty echo...
+            p.expect(['1234']) # ... and again from cat itself.
+            p.setecho(False) # Turn off tty echo
+            p.sendline('abcd') # We will set this only once (echoed by cat).
+            p.sendline('wxyz') # We will set this only once (echoed by cat)
+            p.expect(['abcd'])
+            p.expect(['wxyz'])
+
+        The following WILL NOT WORK because the lines sent before the setecho
+        will be lost::
+
+            p = pexpect.spawn('cat')
+            p.sendline('1234')
+            p.setecho(False) # Turn off tty echo
+            p.sendline('abcd') # We will set this only once (echoed by cat).
+            p.sendline('wxyz') # We will set this only once (echoed by cat)
+            p.expect(['1234'])
+            p.expect(['1234'])
+            p.expect(['abcd'])
+            p.expect(['wxyz'])
+
+
+        Not supported on platforms where ``isatty()`` returns False.
+        '''
+        return self.ptyproc.setecho(state)
+
+        self.echo = state
+
+    def read_nonblocking(self, size=1, timeout=-1):
+        '''This reads at most size characters from the child application. It
+        includes a timeout. If the read does not complete within the timeout
+        period then a TIMEOUT exception is raised. If the end of file is read
+        then an EOF exception will be raised. If a log file was set using
+        setlog() then all data will also be written to the log file.
+
+        If timeout is None then the read may block indefinitely.
+        If timeout is -1 then the self.timeout value is used. If timeout is 0
+        then the child is polled and if there is no data immediately ready
+        then this will raise a TIMEOUT exception.
+
+        The timeout refers only to the amount of time to read at least one
+        character. This is not effected by the 'size' parameter, so if you call
+        read_nonblocking(size=100, timeout=30) and only one character is
+        available right away then one character will be returned immediately.
+        It will not wait for 30 seconds for another 99 characters to come in.
+
+        This is a wrapper around os.read(). It uses select.select() to
+        implement the timeout. '''
+
+        if self.closed:
+            raise ValueError('I/O operation on closed file.')
+
+        if timeout == -1:
+            timeout = self.timeout
+
+        # Note that some systems such as Solaris do not give an EOF when
+        # the child dies. In fact, you can still try to read
+        # from the child_fd -- it will block forever or until TIMEOUT.
+        # For this case, I test isalive() before doing any reading.
+        # If isalive() is false, then I pretend that this is the same as EOF.
+        if not self.isalive():
+            # timeout of 0 means "poll"
+            r, w, e = self.__select([self.child_fd], [], [], 0)
+            if not r:
+                self.flag_eof = True
+                raise EOF('End Of File (EOF). Braindead platform.')
+        elif self.__irix_hack:
+            # Irix takes a long time before it realizes a child was terminated.
+            # FIXME So does this mean Irix systems are forced to always have
+            # FIXME a 2 second delay when calling read_nonblocking? That sucks.
+            r, w, e = self.__select([self.child_fd], [], [], 2)
+            if not r and not self.isalive():
+                self.flag_eof = True
+                raise EOF('End Of File (EOF). Slow platform.')
+
+        r, w, e = self.__select([self.child_fd], [], [], timeout)
+
+        if not r:
+            if not self.isalive():
+                # Some platforms, such as Irix, will claim that their
+                # processes are alive; timeout on the select; and
+                # then finally admit that they are not alive.
+                self.flag_eof = True
+                raise EOF('End of File (EOF). Very slow platform.')
+            else:
+                raise TIMEOUT('Timeout exceeded.')
+
+        if self.child_fd in r:
+            return super(spawn, self).read_nonblocking(size)
+
+        raise ExceptionPexpect('Reached an unexpected state.')  # pragma: no cover
+
+    def write(self, s):
+        '''This is similar to send() except that there is no return value.
+        '''
+
+        self.send(s)
+
+    def writelines(self, sequence):
+        '''This calls write() for each element in the sequence. The sequence
+        can be any iterable object producing strings, typically a list of
+        strings. This does not add line separators. There is no return value.
+        '''
+
+        for s in sequence:
+            self.write(s)
+
+    def send(self, s):
+        '''Sends string ``s`` to the child process, returning the number of
+        bytes written. If a logfile is specified, a copy is written to that
+        log.
+
+        The default terminal input mode is canonical processing unless set
+        otherwise by the child process. This allows backspace and other line
+        processing to be performed prior to transmitting to the receiving
+        program. As this is buffered, there is a limited size of such buffer.
+
+        On Linux systems, this is 4096 (defined by N_TTY_BUF_SIZE). All
+        other systems honor the POSIX.1 definition PC_MAX_CANON -- 1024
+        on OSX, 256 on OpenSolaris, 255 on FreeBSD.
+
+        This value may be discovered using fpathconf(3)::
+
+        >>> from os import fpathconf
+        >>> print(fpathconf(0, 'PC_MAX_CANON'))
+        256
+
+        On such a system, only 256 bytes may be received per line. Any
+        subsequent bytes received will be discarded. BEL (``'\a'``) is then
+        sent to output if IMAXBEL (termios.h) is set by the tty driver.
+        This is usually enabled by default.  Linux does not honor this as
+        an option -- it behaves as though it is always set on.
+
+        Canonical input processing may be disabled altogether by executing
+        a shell, then stty(1), before executing the final program::
+
+        >>> bash = pexpect.spawn('/bin/bash', echo=False)
+        >>> bash.sendline('stty -icanon')
+        >>> bash.sendline('base64')
+        >>> bash.sendline('x' * 5000)
+        '''
+
+        time.sleep(self.delaybeforesend)
+
+        s = self._coerce_send_string(s)
+        self._log(s, 'send')
+
+        return self._send(s)
+
+    def _send(self, s):
+        return os.write(self.child_fd, s)
+
+    def sendline(self, s=''):
+        '''Wraps send(), sending string ``s`` to child process, with
+        ``os.linesep`` automatically appended. Returns number of bytes
+        written.  Only a limited number of bytes may be sent for each
+        line in the default terminal mode, see docstring of :meth:`send`.
+        '''
+
+        n = self.send(s)
+        n = n + self.send(self.linesep)
+        return n
+
+    def _log_control(self, byte):
+        """Write control characters to the appropriate log files"""
+        self._log(byte, 'send')
+
+    def sendcontrol(self, char):
+        '''Helper method that wraps send() with mnemonic access for sending control
+        character to the child (such as Ctrl-C or Ctrl-D).  For example, to send
+        Ctrl-G (ASCII 7, bell, '\a')::
+
+            child.sendcontrol('g')
+
+        See also, sendintr() and sendeof().
+        '''
+        n, byte = self.ptyproc.sendcontrol(char)
+        self._log_control(byte)
+        return n
+
+    def sendeof(self):
+        '''This sends an EOF to the child. This sends a character which causes
+        the pending parent output buffer to be sent to the waiting child
+        program without waiting for end-of-line. If it is the first character
+        of the line, the read() in the user program returns 0, which signifies
+        end-of-file. This means to work as expected a sendeof() has to be
+        called at the beginning of a line. This method does not send a newline.
+        It is the responsibility of the caller to ensure the eof is sent at the
+        beginning of a line. '''
+
+        n, byte = self.ptyproc.sendeof()
+        self._log_control(byte)
+
+    def sendintr(self):
+        '''This sends a SIGINT to the child. It does not require
+        the SIGINT to be the first character on a line. '''
+
+        n, byte = self.ptyproc.sendintr()
+        self._log_control(byte)
+
+    @property
+    def flag_eof(self):
+        return self.ptyproc.flag_eof
+
+    @flag_eof.setter
+    def flag_eof(self, value):
+        self.ptyproc.flag_eof = value
+
+    def eof(self):
+        '''This returns True if the EOF exception was ever raised.
+        '''
+        return self.flag_eof
+
+    def terminate(self, force=False):
+        '''This forces a child process to terminate. It starts nicely with
+        SIGHUP and SIGINT. If "force" is True then moves onto SIGKILL. This
+        returns True if the child was terminated. This returns False if the
+        child could not be terminated. '''
+
+        if not self.isalive():
+            return True
+        try:
+            self.kill(signal.SIGHUP)
+            time.sleep(self.delayafterterminate)
+            if not self.isalive():
+                return True
+            self.kill(signal.SIGCONT)
+            time.sleep(self.delayafterterminate)
+            if not self.isalive():
+                return True
+            self.kill(signal.SIGINT)
+            time.sleep(self.delayafterterminate)
+            if not self.isalive():
+                return True
+            if force:
+                self.kill(signal.SIGKILL)
+                time.sleep(self.delayafterterminate)
+                if not self.isalive():
+                    return True
+                else:
+                    return False
+            return False
+        except OSError:
+            # I think there are kernel timing issues that sometimes cause
+            # this to happen. I think isalive() reports True, but the
+            # process is dead to the kernel.
+            # Make one last attempt to see if the kernel is up to date.
+            time.sleep(self.delayafterterminate)
+            if not self.isalive():
+                return True
+            else:
+                return False
+
+    def wait(self):
+        '''This waits until the child exits. This is a blocking call. This will
+        not read any data from the child, so this will block forever if the
+        child has unread output and has terminated. In other words, the child
+        may have printed output then called exit(), but, the child is
+        technically still alive until its output is read by the parent. '''
+
+        ptyproc = self.ptyproc
+        with _wrap_ptyprocess_err():
+            exitstatus = ptyproc.wait()
+        self.status = ptyproc.status
+        self.exitstatus = ptyproc.exitstatus
+        self.signalstatus = ptyproc.signalstatus
+        self.terminated = True
+
+        return exitstatus
+
+    def isalive(self):
+        '''This tests if the child process is running or not. This is
+        non-blocking. If the child was terminated then this will read the
+        exitstatus or signalstatus of the child. This returns True if the child
+        process appears to be running or False if not. It can take literally
+        SECONDS for Solaris to return the right status. '''
+
+        ptyproc = self.ptyproc
+        with _wrap_ptyprocess_err():
+            alive = ptyproc.isalive()
+
+        if not alive:
+            self.status = ptyproc.status
+            self.exitstatus = ptyproc.exitstatus
+            self.signalstatus = ptyproc.signalstatus
+            self.terminated = True
+
+        return alive
+
+    def kill(self, sig):
+
+        '''This sends the given signal to the child application. In keeping
+        with UNIX tradition it has a misleading name. It does not necessarily
+        kill the child unless you send the right signal. '''
+
+        # Same as os.kill, but the pid is given for you.
+        if self.isalive():
+            os.kill(self.pid, sig)
+
+    def getwinsize(self):
+        '''This returns the terminal window size of the child tty. The return
+        value is a tuple of (rows, cols). '''
+        return self.ptyproc.getwinsize()
+
+    def setwinsize(self, rows, cols):
+        '''This sets the terminal window size of the child tty. This will cause
+        a SIGWINCH signal to be sent to the child. This does not change the
+        physical window size. It changes the size reported to TTY-aware
+        applications like vi or curses -- applications that respond to the
+        SIGWINCH signal. '''
+        return self.ptyproc.setwinsize(rows, cols)
+
+
+    def interact(self, escape_character=chr(29),
+            input_filter=None, output_filter=None):
+
+        '''This gives control of the child process to the interactive user (the
+        human at the keyboard). Keystrokes are sent to the child process, and
+        the stdout and stderr output of the child process is printed. This
+        simply echos the child stdout and child stderr to the real stdout and
+        it echos the real stdin to the child stdin. When the user types the
+        escape_character this method will stop. The default for
+        escape_character is ^]. This should not be confused with ASCII 27 --
+        the ESC character. ASCII 29 was chosen for historical merit because
+        this is the character used by 'telnet' as the escape character. The
+        escape_character will not be sent to the child process.
+
+        You may pass in optional input and output filter functions. These
+        functions should take a string and return a string. The output_filter
+        will be passed all the output from the child process. The input_filter
+        will be passed all the keyboard input from the user. The input_filter
+        is run BEFORE the check for the escape_character.
+
+        Note that if you change the window size of the parent the SIGWINCH
+        signal will not be passed through to the child. If you want the child
+        window size to change when the parent's window size changes then do
+        something like the following example::
+
+            import pexpect, struct, fcntl, termios, signal, sys
+            def sigwinch_passthrough (sig, data):
+                s = struct.pack("HHHH", 0, 0, 0, 0)
+                a = struct.unpack('hhhh', fcntl.ioctl(sys.stdout.fileno(),
+                    termios.TIOCGWINSZ , s))
+                global p
+                p.setwinsize(a[0],a[1])
+            # Note this 'p' global and used in sigwinch_passthrough.
+            p = pexpect.spawn('/bin/bash')
+            signal.signal(signal.SIGWINCH, sigwinch_passthrough)
+            p.interact()
+        '''
+
+        # Flush the buffer.
+        self.write_to_stdout(self.buffer)
+        self.stdout.flush()
+        self.buffer = self.string_type()
+        mode = tty.tcgetattr(self.STDIN_FILENO)
+        tty.setraw(self.STDIN_FILENO)
+        if PY3:
+            escape_character = escape_character.encode('latin-1')
+        try:
+            self.__interact_copy(escape_character, input_filter, output_filter)
+        finally:
+            tty.tcsetattr(self.STDIN_FILENO, tty.TCSAFLUSH, mode)
+
+    def __interact_writen(self, fd, data):
+        '''This is used by the interact() method.
+        '''
+
+        while data != b'' and self.isalive():
+            n = os.write(fd, data)
+            data = data[n:]
+
+    def __interact_read(self, fd):
+        '''This is used by the interact() method.
+        '''
+
+        return os.read(fd, 1000)
+
+    def __interact_copy(self, escape_character=None,
+            input_filter=None, output_filter=None):
+
+        '''This is used by the interact() method.
+        '''
+
+        while self.isalive():
+            r, w, e = self.__select([self.child_fd, self.STDIN_FILENO], [], [])
+            if self.child_fd in r:
+                try:
+                    data = self.__interact_read(self.child_fd)
+                except OSError as err:
+                    if err.args[0] == errno.EIO:
+                        # Linux-style EOF
+                        break
+                    raise
+                if data == b'':
+                    # BSD-style EOF
+                    break
+                if output_filter:
+                    data = output_filter(data)
+                if self.logfile is not None:
+                    self.logfile.write(data)
+                    self.logfile.flush()
+                os.write(self.STDOUT_FILENO, data)
+            if self.STDIN_FILENO in r:
+                data = self.__interact_read(self.STDIN_FILENO)
+                if input_filter:
+                    data = input_filter(data)
+                i = data.rfind(escape_character)
+                if i != -1:
+                    data = data[:i]
+                    self.__interact_writen(self.child_fd, data)
+                    break
+                self.__interact_writen(self.child_fd, data)
+
+    def __select(self, iwtd, owtd, ewtd, timeout=None):
+
+        '''This is a wrapper around select.select() that ignores signals. If
+        select.select raises a select.error exception and errno is an EINTR
+        error then it is ignored. Mainly this is used to ignore sigwinch
+        (terminal resize). '''
+
+        # if select() is interrupted by a signal (errno==EINTR) then
+        # we loop back and enter the select() again.
+        if timeout is not None:
+            end_time = time.time() + timeout
+        while True:
+            try:
+                return select.select(iwtd, owtd, ewtd, timeout)
+            except select.error:
+                err = sys.exc_info()[1]
+                if err.args[0] == errno.EINTR:
+                    # if we loop back we have to subtract the
+                    # amount of time we already waited.
+                    if timeout is not None:
+                        timeout = end_time - time.time()
+                        if timeout < 0:
+                            return([], [], [])
+                else:
+                    # something else caused the select.error, so
+                    # this actually is an exception.
+                    raise
+
+
+class spawnu(SpawnBaseUnicode, spawn):
+    """Works like spawn, but accepts and returns unicode strings.
+
+    Extra parameters:
+
+    :param encoding: The encoding to use for communications (default: 'utf-8')
+    :param errors: How to handle encoding/decoding errors; one of 'strict'
+                   (the default), 'ignore', or 'replace', as described
+                   for :meth:`~bytes.decode` and :meth:`~str.encode`.
+    """
+    ptyprocess_class = ptyprocess.PtyProcessUnicode
+
+    def _send(self, s):
+        return os.write(self.child_fd, s.encode(self.encoding, self.errors))
+
+    def _log_control(self, byte):
+        s = byte.decode(self.encoding, 'replace')
+        self._log(s, 'send')
diff --git a/pexpect/pxssh.py b/pexpect/pxssh.py
index bd34f97..71f56a0 100644
--- a/pexpect/pxssh.py
+++ b/pexpect/pxssh.py
@@ -68,6 +68,14 @@ class pxssh (spawn):
             print("pxssh failed on login.")
             print(e)
 
+    Example showing how to specify SSH options::
+
+        import pxssh
+        s = pxssh.pxssh(options={
+                            "StrictHostKeyChecking": "no",
+                            "UserKnownHostsFile": "/dev/null"})
+        ...
+
     Note that if you have ssh-agent running while doing development with pxssh
     then this can lead to a lot of confusion. Many X display managers (xdm,
     gdm, kdm, etc.) will automatically start a GUI agent. You may see a GUI
@@ -86,7 +94,8 @@ class pxssh (spawn):
     '''
 
     def __init__ (self, timeout=30, maxread=2000, searchwindowsize=None,
-                    logfile=None, cwd=None, env=None, ignore_sighup=True, echo=True):
+                    logfile=None, cwd=None, env=None, ignore_sighup=True, echo=True,
+                    options={}):
 
         spawn.__init__(self, None, timeout=timeout, maxread=maxread, searchwindowsize=searchwindowsize, logfile=logfile, cwd=cwd, env=env, ignore_sighup=ignore_sighup, echo=echo)
 
@@ -120,6 +129,10 @@ class pxssh (spawn):
         #self.SSH_OPTS = "-x -o'RSAAuthentication=no' -o 'PubkeyAuthentication=no'"
         self.force_password = False
 
+        # User defined SSH options, eg,
+        # ssh.otions = dict(StrictHostKeyChecking="no",UserKnownHostsFile="/dev/null")
+        self.options = options
+
     def levenshtein_distance(self, a, b):
         '''This calculates the Levenshtein distance between a and b.
         '''
@@ -165,7 +178,7 @@ class pxssh (spawn):
             try:
                 prompt += self.read_nonblocking(size=1, timeout=timeout)
                 expired = time.time() - begin # updated total time expired
-                timeout = inter_char_timeout 
+                timeout = inter_char_timeout
             except TIMEOUT:
                 break
 
@@ -241,7 +254,7 @@ class pxssh (spawn):
         manually set the :attr:`PROMPT` attribute.
         '''
 
-        ssh_options = ''
+        ssh_options = ''.join([" -o '%s=%s'" % (o, v) for (o, v) in self.options.items()])
         if quiet:
             ssh_options = ssh_options + ' -q'
         if not check_local_ip:
diff --git a/pexpect/replwrap.py b/pexpect/replwrap.py
index 0c879ff..7b0e823 100644
--- a/pexpect/replwrap.py
+++ b/pexpect/replwrap.py
@@ -108,6 +108,6 @@ def python(command="python"):
 def bash(command="bash"):
     """Start a bash shell and return a :class:`REPLWrapper` object."""
     bashrc = os.path.join(os.path.dirname(__file__), 'bashrc.sh')
-    child = pexpect.spawnu(command, ['--rcfile', bashrc])
+    child = pexpect.spawnu(command, ['--rcfile', bashrc], echo=False)
     return REPLWrapper(child, u'\$', u("PS1='{0}' PS2='{1}' PROMPT_COMMAND=''"),
                        extra_init_cmd="export PAGER=cat")
diff --git a/pexpect/spawnbase.py b/pexpect/spawnbase.py
new file mode 100644
index 0000000..b1bc2f3
--- /dev/null
+++ b/pexpect/spawnbase.py
@@ -0,0 +1,475 @@
+import codecs
+import os
+import sys
+import re
+import errno
+from .exceptions import ExceptionPexpect, EOF, TIMEOUT
+from .expect import Expecter, searcher_string, searcher_re
+
+PY3 = (sys.version_info[0] >= 3)
+
+class SpawnBase(object):
+    """A base class providing the backwards-compatible spawn API for Pexpect.
+
+    This should not be instantiated directly: use :class:`pexpect.spawn` or :class:`pexpect.fdpexpect.fdspawn`."""
+    string_type = bytes
+    if PY3:
+        allowed_string_types = (bytes, str)
+        linesep = os.linesep.encode('ascii')
+        crlf = '\r\n'.encode('ascii')
+
+        @staticmethod
+        def write_to_stdout(b):
+            try:
+                return sys.stdout.buffer.write(b)
+            except AttributeError:
+                # If stdout has been replaced, it may not have .buffer
+                return sys.stdout.write(b.decode('ascii', 'replace'))
+    else:
+        allowed_string_types = (basestring,)  # analysis:ignore
+        linesep = os.linesep
+        crlf = '\r\n'
+        write_to_stdout = sys.stdout.write
+
+    encoding = None
+    pid = None
+    flag_eof = False
+
+    def __init__(self, timeout=30, maxread=2000, searchwindowsize=None, logfile=None):
+        self.stdin = sys.stdin
+        self.stdout = sys.stdout
+        self.stderr = sys.stderr
+
+        self.searcher = None
+        self.ignorecase = False
+        self.before = None
+        self.after = None
+        self.match = None
+        self.match_index = None
+        self.terminated = True
+        self.exitstatus = None
+        self.signalstatus = None
+        # status returned by os.waitpid
+        self.status = None
+        # the child file descriptor is initially closed
+        self.child_fd = -1
+        self.timeout = timeout
+        self.delimiter = EOF
+        self.logfile = logfile
+        # input from child (read_nonblocking)
+        self.logfile_read = None
+        # output to send (send, sendline)
+        self.logfile_send = None
+        # max bytes to read at one time into buffer
+        self.maxread = maxread
+        # This is the read buffer. See maxread.
+        self.buffer = self.string_type()
+        # Data before searchwindowsize point is preserved, but not searched.
+        self.searchwindowsize = searchwindowsize
+        # Delay used before sending data to child. Time in seconds.
+        # Most Linux machines don't like this to be below 0.03 (30 ms).
+        self.delaybeforesend = 0.05
+        # Used by close() to give kernel time to update process status.
+        # Time in seconds.
+        self.delayafterclose = 0.1
+        # Used by terminate() to give kernel time to update process status.
+        # Time in seconds.
+        self.delayafterterminate = 0.1
+        self.softspace = False
+        self.name = '<' + repr(self) + '>'
+        self.closed = True
+
+    def _log(self, s, direction):
+        if self.logfile is not None:
+            self.logfile.write(s)
+            self.logfile.flush()
+        second_log = self.logfile_send if (direction=='send') else self.logfile_read
+        if second_log is not None:
+            second_log.write(s)
+            second_log.flush()
+
+    @staticmethod
+    def _coerce_expect_string(s):
+        if not isinstance(s, bytes):
+            return s.encode('ascii')
+        return s
+
+    @staticmethod
+    def _coerce_send_string(s):
+        if not isinstance(s, bytes):
+            return s.encode('utf-8')
+        return s
+
+    @staticmethod
+    def _coerce_read_string(s):
+        return s
+
+    def read_nonblocking(self, size=1, timeout=None):
+        """This reads data from the file descriptor.
+
+        This is a simple implementation suitable for a regular file. Subclasses using ptys or pipes should override it.
+
+        The timeout parameter is ignored.
+        """
+
+        try:
+            s = os.read(self.child_fd, size)
+        except OSError as err:
+            if err.args[0] == errno.EIO:
+                # Linux-style EOF
+                self.flag_eof = True
+                raise EOF('End Of File (EOF). Exception style platform.')
+            raise
+        if s == b'':
+            # BSD-style EOF
+            self.flag_eof = True
+            raise EOF('End Of File (EOF). Empty string style platform.')
+
+        s = self._coerce_read_string(s)
+        self._log(s, 'read')
+        return s
+
+    def _pattern_type_err(self, pattern):
+        raise TypeError('got {badtype} ({badobj!r}) as pattern, must be one'
+                        ' of: {goodtypes}, pexpect.EOF, pexpect.TIMEOUT'\
+                        .format(badtype=type(pattern),
+                                badobj=pattern,
+                                goodtypes=', '.join([str(ast)\
+                                    for ast in self.allowed_string_types])
+                                )
+                        )
+
+    def compile_pattern_list(self, patterns):
+        '''This compiles a pattern-string or a list of pattern-strings.
+        Patterns must be a StringType, EOF, TIMEOUT, SRE_Pattern, or a list of
+        those. Patterns may also be None which results in an empty list (you
+        might do this if waiting for an EOF or TIMEOUT condition without
+        expecting any pattern).
+
+        This is used by expect() when calling expect_list(). Thus expect() is
+        nothing more than::
+
+             cpl = self.compile_pattern_list(pl)
+             return self.expect_list(cpl, timeout)
+
+        If you are using expect() within a loop it may be more
+        efficient to compile the patterns first and then call expect_list().
+        This avoid calls in a loop to compile_pattern_list()::
+
+             cpl = self.compile_pattern_list(my_pattern)
+             while some_condition:
+                ...
+                i = self.expect_list(cpl, timeout)
+                ...
+        '''
+
+        if patterns is None:
+            return []
+        if not isinstance(patterns, list):
+            patterns = [patterns]
+
+        # Allow dot to match \n
+        compile_flags = re.DOTALL
+        if self.ignorecase:
+            compile_flags = compile_flags | re.IGNORECASE
+        compiled_pattern_list = []
+        for idx, p in enumerate(patterns):
+            if isinstance(p, self.allowed_string_types):
+                p = self._coerce_expect_string(p)
+                compiled_pattern_list.append(re.compile(p, compile_flags))
+            elif p is EOF:
+                compiled_pattern_list.append(EOF)
+            elif p is TIMEOUT:
+                compiled_pattern_list.append(TIMEOUT)
+            elif isinstance(p, type(re.compile(''))):
+                compiled_pattern_list.append(p)
+            else:
+                self._pattern_type_err(p)
+        return compiled_pattern_list
+
+    def expect(self, pattern, timeout=-1, searchwindowsize=-1, async=False):
+        '''This seeks through the stream until a pattern is matched. The
+        pattern is overloaded and may take several types. The pattern can be a
+        StringType, EOF, a compiled re, or a list of any of those types.
+        Strings will be compiled to re types. This returns the index into the
+        pattern list. If the pattern was not a list this returns index 0 on a
+        successful match. This may raise exceptions for EOF or TIMEOUT. To
+        avoid the EOF or TIMEOUT exceptions add EOF or TIMEOUT to the pattern
+        list. That will cause expect to match an EOF or TIMEOUT condition
+        instead of raising an exception.
+
+        If you pass a list of patterns and more than one matches, the first
+        match in the stream is chosen. If more than one pattern matches at that
+        point, the leftmost in the pattern list is chosen. For example::
+
+            # the input is 'foobar'
+            index = p.expect(['bar', 'foo', 'foobar'])
+            # returns 1('foo') even though 'foobar' is a "better" match
+
+        Please note, however, that buffering can affect this behavior, since
+        input arrives in unpredictable chunks. For example::
+
+            # the input is 'foobar'
+            index = p.expect(['foobar', 'foo'])
+            # returns 0('foobar') if all input is available at once,
+            # but returs 1('foo') if parts of the final 'bar' arrive late
+
+        After a match is found the instance attributes 'before', 'after' and
+        'match' will be set. You can see all the data read before the match in
+        'before'. You can see the data that was matched in 'after'. The
+        re.MatchObject used in the re match will be in 'match'. If an error
+        occurred then 'before' will be set to all the data read so far and
+        'after' and 'match' will be None.
+
+        If timeout is -1 then timeout will be set to the self.timeout value.
+
+        A list entry may be EOF or TIMEOUT instead of a string. This will
+        catch these exceptions and return the index of the list entry instead
+        of raising the exception. The attribute 'after' will be set to the
+        exception type. The attribute 'match' will be None. This allows you to
+        write code like this::
+
+                index = p.expect(['good', 'bad', pexpect.EOF, pexpect.TIMEOUT])
+                if index == 0:
+                    do_something()
+                elif index == 1:
+                    do_something_else()
+                elif index == 2:
+                    do_some_other_thing()
+                elif index == 3:
+                    do_something_completely_different()
+
+        instead of code like this::
+
+                try:
+                    index = p.expect(['good', 'bad'])
+                    if index == 0:
+                        do_something()
+                    elif index == 1:
+                        do_something_else()
+                except EOF:
+                    do_some_other_thing()
+                except TIMEOUT:
+                    do_something_completely_different()
+
+        These two forms are equivalent. It all depends on what you want. You
+        can also just expect the EOF if you are waiting for all output of a
+        child to finish. For example::
+
+                p = pexpect.spawn('/bin/ls')
+                p.expect(pexpect.EOF)
+                print p.before
+
+        If you are trying to optimize for speed then see expect_list().
+
+        On Python 3.4, or Python 3.3 with asyncio installed, passing
+        ``async=True``  will make this return an :mod:`asyncio` coroutine,
+        which you can yield from to get the same result that this method would
+        normally give directly. So, inside a coroutine, you can replace this code::
+
+            index = p.expect(patterns)
+
+        With this non-blocking form::
+
+            index = yield from p.expect(patterns, async=True)
+        '''
+
+        compiled_pattern_list = self.compile_pattern_list(pattern)
+        return self.expect_list(compiled_pattern_list,
+                timeout, searchwindowsize, async)
+
+    def expect_list(self, pattern_list, timeout=-1, searchwindowsize=-1,
+                    async=False):
+        '''This takes a list of compiled regular expressions and returns the
+        index into the pattern_list that matched the child output. The list may
+        also contain EOF or TIMEOUT(which are not compiled regular
+        expressions). This method is similar to the expect() method except that
+        expect_list() does not recompile the pattern list on every call. This
+        may help if you are trying to optimize for speed, otherwise just use
+        the expect() method.  This is called by expect(). If timeout==-1 then
+        the self.timeout value is used. If searchwindowsize==-1 then the
+        self.searchwindowsize value is used.
+
+        Like :meth:`expect`, passing ``async=True`` will make this return an
+        asyncio coroutine.
+        '''
+        if timeout == -1:
+            timeout = self.timeout
+
+        exp = Expecter(self, searcher_re(pattern_list), searchwindowsize)
+        if async:
+            from .async import expect_async
+            return expect_async(exp, timeout)
+        else:
+            return exp.expect_loop(timeout)
+
+    def expect_exact(self, pattern_list, timeout=-1, searchwindowsize=-1,
+                     async=False):
+
+        '''This is similar to expect(), but uses plain string matching instead
+        of compiled regular expressions in 'pattern_list'. The 'pattern_list'
+        may be a string; a list or other sequence of strings; or TIMEOUT and
+        EOF.
+
+        This call might be faster than expect() for two reasons: string
+        searching is faster than RE matching and it is possible to limit the
+        search to just the end of the input buffer.
+
+        This method is also useful when you don't want to have to worry about
+        escaping regular expression characters that you want to match.
+
+        Like :meth:`expect`, passing ``async=True`` will make this return an
+        asyncio coroutine.
+        '''
+        if timeout == -1:
+            timeout = self.timeout
+
+        if (isinstance(pattern_list, self.allowed_string_types) or
+                pattern_list in (TIMEOUT, EOF)):
+            pattern_list = [pattern_list]
+
+        def prepare_pattern(pattern):
+            if pattern in (TIMEOUT, EOF):
+                return pattern
+            if isinstance(pattern, self.allowed_string_types):
+                return self._coerce_expect_string(pattern)
+            self._pattern_type_err(pattern)
+
+        try:
+            pattern_list = iter(pattern_list)
+        except TypeError:
+            self._pattern_type_err(pattern_list)
+        pattern_list = [prepare_pattern(p) for p in pattern_list]
+
+        exp = Expecter(self, searcher_string(pattern_list), searchwindowsize)
+        if async:
+            from .async import expect_async
+            return expect_async(exp, timeout)
+        else:
+            return exp.expect_loop(timeout)
+
+    def expect_loop(self, searcher, timeout=-1, searchwindowsize=-1):
+        '''This is the common loop used inside expect. The 'searcher' should be
+        an instance of searcher_re or searcher_string, which describes how and
+        what to search for in the input.
+
+        See expect() for other arguments, return value and exceptions. '''
+
+        exp = Expecter(self, searcher, searchwindowsize)
+        return exp.expect_loop(timeout)
+
+    def read(self, size=-1):
+        '''This reads at most "size" bytes from the file (less if the read hits
+        EOF before obtaining size bytes). If the size argument is negative or
+        omitted, read all data until EOF is reached. The bytes are returned as
+        a string object. An empty string is returned when EOF is encountered
+        immediately. '''
+
+        if size == 0:
+            return self.string_type()
+        if size < 0:
+            # delimiter default is EOF
+            self.expect(self.delimiter)
+            return self.before
+
+        # I could have done this more directly by not using expect(), but
+        # I deliberately decided to couple read() to expect() so that
+        # I would catch any bugs early and ensure consistant behavior.
+        # It's a little less efficient, but there is less for me to
+        # worry about if I have to later modify read() or expect().
+        # Note, it's OK if size==-1 in the regex. That just means it
+        # will never match anything in which case we stop only on EOF.
+        cre = re.compile(self._coerce_expect_string('.{%d}' % size), re.DOTALL)
+        # delimiter default is EOF
+        index = self.expect([cre, self.delimiter])
+        if index == 0:
+            ### FIXME self.before should be ''. Should I assert this?
+            return self.after
+        return self.before
+
+    def readline(self, size=-1):
+        '''This reads and returns one entire line. The newline at the end of
+        line is returned as part of the string, unless the file ends without a
+        newline. An empty string is returned if EOF is encountered immediately.
+        This looks for a newline as a CR/LF pair (\\r\\n) even on UNIX because
+        this is what the pseudotty device returns. So contrary to what you may
+        expect you will receive newlines as \\r\\n.
+
+        If the size argument is 0 then an empty string is returned. In all
+        other cases the size argument is ignored, which is not standard
+        behavior for a file-like object. '''
+
+        if size == 0:
+            return self.string_type()
+        # delimiter default is EOF
+        index = self.expect([self.crlf, self.delimiter])
+        if index == 0:
+            return self.before + self.crlf
+        else:
+            return self.before
+
+    def __iter__(self):
+        '''This is to support iterators over a file-like object.
+        '''
+        return iter(self.readline, self.string_type())
+
+    def readlines(self, sizehint=-1):
+        '''This reads until EOF using readline() and returns a list containing
+        the lines thus read. The optional 'sizehint' argument is ignored.
+        Remember, because this reads until EOF that means the child
+        process should have closed its stdout. If you run this method on
+        a child that is still running with its stdout open then this
+        method will block until it timesout.'''
+
+        lines = []
+        while True:
+            line = self.readline()
+            if not line:
+                break
+            lines.append(line)
+        return lines
+
+    def fileno(self):
+        '''Expose file descriptor for a file-like interface
+        '''
+        return self.child_fd
+
+    def flush(self):
+        '''This does nothing. It is here to support the interface for a
+        File-like object. '''
+        pass
+
+    def isatty(self):
+        """Overridden in subclass using tty"""
+        return False
+
+class SpawnBaseUnicode(SpawnBase):
+    if PY3:
+        string_type = str
+        allowed_string_types = (str, )
+        linesep = os.linesep
+        crlf = '\r\n'
+    else:
+        string_type = unicode
+        allowed_string_types = (unicode, )
+        linesep = os.linesep.decode('ascii')
+        crlf = '\r\n'.decode('ascii')
+    # This can handle unicode in both Python 2 and 3
+    write_to_stdout = sys.stdout.write
+
+    def __init__(self, *args, **kwargs):
+        self.encoding = kwargs.pop('encoding', 'utf-8')
+        self.errors = kwargs.pop('errors', 'strict')
+        self._decoder = codecs.getincrementaldecoder(self.encoding)(errors=self.errors)
+        super(SpawnBaseUnicode, self).__init__(*args, **kwargs)
+
+    @staticmethod
+    def _coerce_expect_string(s):
+        return s
+
+    @staticmethod
+    def _coerce_send_string(s):
+        return s
+
+    def _coerce_read_string(self, s):
+        return self._decoder.decode(s, final=False)
\ No newline at end of file
diff --git a/pexpect/utils.py b/pexpect/utils.py
new file mode 100644
index 0000000..737f0ed
--- /dev/null
+++ b/pexpect/utils.py
@@ -0,0 +1,112 @@
+import os
+import sys
+import stat
+
+
+def is_executable_file(path):
+    """Checks that path is an executable regular file, or a symlink towards one.
+
+    This is roughly ``os.path isfile(path) and os.access(path, os.X_OK)``.
+    """
+    # follow symlinks,
+    fpath = os.path.realpath(path)
+
+    if not os.path.isfile(fpath):
+        # non-files (directories, fifo, etc.)
+        return False
+
+    mode = os.stat(fpath).st_mode
+
+    if (sys.platform.startswith('sunos')
+            and os.getuid() == 0):
+        # When root on Solaris, os.X_OK is True for *all* files, irregardless
+        # of their executability -- instead, any permission bit of any user,
+        # group, or other is fine enough.
+        #
+        # (This may be true for other "Unix98" OS's such as HP-UX and AIX)
+        return bool(mode & (stat.S_IXUSR |
+                            stat.S_IXGRP |
+                            stat.S_IXOTH))
+
+    return os.access(fpath, os.X_OK)
+
+
+def which(filename):
+    '''This takes a given filename; tries to find it in the environment path;
+    then checks if it is executable. This returns the full path to the filename
+    if found and executable. Otherwise this returns None.'''
+
+    # Special case where filename contains an explicit path.
+    if os.path.dirname(filename) != '' and is_executable_file(filename):
+        return filename
+    if 'PATH' not in os.environ or os.environ['PATH'] == '':
+        p = os.defpath
+    else:
+        p = os.environ['PATH']
+    pathlist = p.split(os.pathsep)
+    for path in pathlist:
+        ff = os.path.join(path, filename)
+        if is_executable_file(ff):
+            return ff
+    return None
+
+
+def split_command_line(command_line):
+
+    '''This splits a command line into a list of arguments. It splits arguments
+    on spaces, but handles embedded quotes, doublequotes, and escaped
+    characters. It's impossible to do this with a regular expression, so I
+    wrote a little state machine to parse the command line. '''
+
+    arg_list = []
+    arg = ''
+
+    # Constants to name the states we can be in.
+    state_basic = 0
+    state_esc = 1
+    state_singlequote = 2
+    state_doublequote = 3
+    # The state when consuming whitespace between commands.
+    state_whitespace = 4
+    state = state_basic
+
+    for c in command_line:
+        if state == state_basic or state == state_whitespace:
+            if c == '\\':
+                # Escape the next character
+                state = state_esc
+            elif c == r"'":
+                # Handle single quote
+                state = state_singlequote
+            elif c == r'"':
+                # Handle double quote
+                state = state_doublequote
+            elif c.isspace():
+                # Add arg to arg_list if we aren't in the middle of whitespace.
+                if state == state_whitespace:
+                    # Do nothing.
+                    None
+                else:
+                    arg_list.append(arg)
+                    arg = ''
+                    state = state_whitespace
+            else:
+                arg = arg + c
+                state = state_basic
+        elif state == state_esc:
+            arg = arg + c
+            state = state_basic
+        elif state == state_singlequote:
+            if c == r"'":
+                state = state_basic
+            else:
+                arg = arg + c
+        elif state == state_doublequote:
+            if c == r'"':
+                state = state_basic
+            else:
+                arg = arg + c
+
+    if arg != '':
+        arg_list.append(arg)
+    return arg_list