Roll third_party/pexpect 509:533

third_party/pexpect/pexpect.py

 """Pexpect is a Python module for spawning child applications and controlling
 them automatically. Pexpect can be used for automating interactive applications
 such as ssh, ftp, passwd, telnet, etc. It can be used to a automate setup
 scripts for duplicating software package installations on different servers. It
 can be used for automated software testing. Pexpect is in the spirit of Don
 Libes' Expect, but Pexpect is pure Python. Other Expect-like modules for Python
 require TCL and Expect or require C extensions to be compiled. Pexpect does not
 use C, Expect, or TCL extensions. It should work on any platform that supports
 the standard Python pty module. The Pexpect interface focuses on ease of use so
 that simple tasks are easy.
 
-There are two main interfaces to Pexpect -- the function, run() and the class,
-spawn. You can call the run() function to execute a command and return the
+There are two main interfaces to the Pexpect system; these are the function,
+run() and the class, spawn. The spawn class is more powerful. The run()
+function is simpler than spawn, and is good for quickly calling program. When
+you call the run() function it executes a given program and then returns the
 output. This is a handy replacement for os.system().
 
 For example::
 
     pexpect.run('ls -la')
 
-The more powerful interface is the spawn class. You can use this to spawn an
-external child command and then interact with the child by sending lines and
-expecting responses.
+The spawn class is the more powerful interface to the Pexpect system. You can
+use this to spawn a child program then interact with it by sending input and
+expecting responses (waiting for patterns in the child's output).
 
 For example::
 
-    child = pexpect.spawn('scp foo myname@host.example.com:.')
-    child.expect ('Password:')
-    child.sendline (mypassword)
+    child = pexpect.spawn('scp foo user@example.com:.')
+    child.expect('Password:')
+    child.sendline(mypassword)
 
 This works even for commands that ask for passwords or other input outside of
-the normal stdio streams.
+the normal stdio streams. For example, ssh reads input directly from the TTY
+device which bypasses stdin.
 
 Credits: Noah Spurrier, Richard Holden, Marco Molteni, Kimberley Burchett,
 Robert Stone, Hartmut Goebel, Chad Schroeder, Erick Tryzelaar, Dave Kirby, Ids
 vander Molen, George Todd, Noel Taylor, Nicolas D. Cesar, Alexander Gattin,
-Geoffrey Marshall, Francisco Lourenco, Glen Mabey, Karthik Gurusamy, Fernando
-Perez, Corey Minyard, Jon Cohen, Guillaume Chazarain, Andrew Ryan, Nick
-Craig-Wood, Andrew Stone, Jorgen Grahn (Let me know if I forgot anyone.)
+Jacques-Etienne Baudoux, Geoffrey Marshall, Francisco Lourenco, Glen Mabey,
+Karthik Gurusamy, Fernando Perez, Corey Minyard, Jon Cohen, Guillaume
+Chazarain, Andrew Ryan, Nick Craig-Wood, Andrew Stone, Jorgen Grahn, John
+Spiegel, Jan Grant, and Shane Kerr. Let me know if I forgot anyone.
 
-Free, open source, and all that good stuff.
-
-Permission is hereby granted, free of charge, to any person obtaining a copy of
-this software and associated documentation files (the "Software"), to deal in
-the Software without restriction, including without limitation the rights to
-use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
-of the Software, and to permit persons to whom the Software is furnished to do
-so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
-
-Pexpect Copyright (c) 2008 Noah Spurrier
+Pexpect is free, open source, and all that good stuff.
 http://pexpect.sourceforge.net/
 
-$Id: pexpect.py 507 2007-12-27 02:40:52Z noah $
+PEXPECT LICENSE
+
+    This license is approved by the OSI and FSF as GPL-compatible.
+        http://opensource.org/licenses/isc-license.txt
+
+    Copyright (c) 2012, Noah Spurrier <noah@noah.org>
+    PERMISSION TO USE, COPY, MODIFY, AND/OR DISTRIBUTE THIS SOFTWARE FOR ANY
+    PURPOSE WITH OR WITHOUT FEE IS HEREBY GRANTED, PROVIDED THAT THE ABOVE
+    COPYRIGHT NOTICE AND THIS PERMISSION NOTICE APPEAR IN ALL COPIES.
+    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+    MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
 """
 
 try:
-    import os, sys, time
+    import os
+    import sys
+    import time
     import select
     import string
     import re
     import struct
     import resource
     import types
     import pty
     import tty
     import termios
     import fcntl
     import errno
     import traceback
     import signal
-except ImportError, e:
-    raise ImportError (str(e) + """
+except ImportError as e:
+    raise ImportError(str(e) + """
 
 A critical module was not found. Probably this operating system does not
 support it. Pexpect is intended for UNIX-like operating systems.""")
 
-__version__ = '2.3'
-__revision__ = '$Revision: 399 $'
+__version__ = '2.6'
+__revision__ = '1'
 __all__ = ['ExceptionPexpect', 'EOF', 'TIMEOUT', 'spawn', 'run', 'which',
     'split_command_line', '__version__', '__revision__']
 
+
 # Exception classes used by this module.
 class ExceptionPexpect(Exception):
 
     """Base class for all exceptions raised by this module.
     """
 
     def __init__(self, value):
 
         self.value = value
 
@@ skipping 15 matching lines @@
 
     def __filter_not_pexpect(self, trace_list_item):
 
         """This returns True if list item 0 the string 'pexpect.py' in it. """
 
         if trace_list_item[0].find('pexpect.py') == -1:
             return True
         else:
             return False
 
+
 class EOF(ExceptionPexpect):
 
-    """Raised when EOF is read from a child. This usually means the child has exited."""
+    """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 scan buffer fills before matching an expected pattern."""
+##    """Raised when a buffer fills before matching an expected pattern."""
 
-def run (command, timeout=-1, withexitstatus=False, events=None, extra_args=None, logfile=None, cwd=None, env=None):
+
+def run(command, timeout=-1, withexitstatus=False, events=None,
+        extra_args=None, logfile=None, cwd=None, env=None):
 
     """
     This function runs the given command; waits for it to finish; then
     returns all output as a string. STDERR is included in output. If the full
     path to the command is not given then the path is searched.
 
     Note that lines are terminated by CR/LF (\\r\\n) combination even on
-    UNIX-like systems because this is the standard for pseudo ttys. If you set
+    UNIX-like systems because this is the standard for pseudottys. If you set
     'withexitstatus' to true, then run will return a tuple of (command_output,
     exitstatus). If 'withexitstatus' is false then this returns just
     command_output.
 
     The run() function can often be used instead of creating a spawn instance.
     For example, the following code uses spawn::
 
         from pexpect import *
-        child = spawn('scp foo myname@host.example.com:.')
-        child.expect ('(?i)password')
-        child.sendline (mypassword)
+        child = spawn('scp foo user@example.com:.')
+        child.expect('(?i)password')
+        child.sendline(mypassword)
 
     The previous code can be replace with the following::
 
         from pexpect import *
-        run ('scp foo myname@host.example.com:.', events={'(?i)password': mypassword})
+        run('scp foo user@example.com:.', events={'(?i)password': mypassword})
 
     Examples
     ========
 
     Start the apache daemon on the local machine::
 
         from pexpect import *
-        run ("/usr/local/apache/bin/apachectl start")
+        run("/usr/local/apache/bin/apachectl start")
 
     Check in a file using SVN::
 
         from pexpect import *
-        run ("svn ci -m 'automatic commit' my_file.py")
+        run("svn ci -m 'automatic commit' my_file.py")
 
     Run a command and capture exit status::
 
         from pexpect import *
-        (command_output, exitstatus) = run ('ls -l /bin', withexitstatus=1)
+        (command_output, exitstatus) = run('ls -l /bin', withexitstatus=1)
 
     Tricky Examples
     ===============
 
     The following will run SSH and execute 'ls -l' on the remote machine. The
     password 'secret' will be sent if the '(?i)password' pattern is ever seen::
 
-        run ("ssh username@machine.example.com 'ls -l'", events={'(?i)password':'secret\\n'})
+        run("ssh username@machine.example.com 'ls -l'",
+            events={'(?i)password':'secret\\n'})
 
     This will start mencoder to rip a video from DVD. This will also display
     progress ticks every 5 seconds as it runs. For example::
 
         from pexpect import *
         def print_ticks(d):
             print d['event_count'],
-        run ("mencoder dvd://1 -o video.avi -oac copy -ovc copy", events={TIMEOUT:print_ticks}, timeout=5)
+        run("mencoder dvd://1 -o video.avi -oac copy -ovc copy",
+            events={TIMEOUT:print_ticks}, timeout=5)
 
     The 'events' argument should be a dictionary of patterns and responses.
     Whenever one of the patterns is seen in the command out run() will send the
     associated response string. Note that you should put newlines in your
     string if Enter is necessary. The responses may also contain callback
     functions. Any callback is function that takes a dictionary as an argument.
     The dictionary contains all the locals from the run() function, so you can
     access the child spawn object or any other variable defined in run()
     (event_count, child, and extra_args are the most useful). A callback may
     return True to stop the current run process otherwise run() continues until
     the next event. A callback may also return a string which will be sent to
     the child. 'extra_args' is not used by directly run(). It provides a way to
     pass data to a callback function through run() through the locals
     dictionary passed to a callback. """
 
     if timeout == -1:
         child = spawn(command, maxread=2000, logfile=logfile, cwd=cwd, env=env)
     else:
-        child = spawn(command, timeout=timeout, maxread=2000, logfile=logfile, cwd=cwd, env=env)
+        child = spawn(command, timeout=timeout, maxread=2000, logfile=logfile,
+                cwd=cwd, env=env)
     if events is not None:
-        patterns = events.keys()
-        responses = events.values()
+        patterns = list(events.keys())
+        responses = list(events.values())
     else:
-        patterns=None # We assume that EOF or TIMEOUT will save us.
-        responses=None
+        # This assumes EOF or TIMEOUT will eventually cause run to terminate.
+        patterns = None
+        responses = None
     child_result_list = []
     event_count = 0
-    while 1:
+    while True:
         try:
-            index = child.expect (patterns)
+            index = child.expect(patterns)
             if type(child.after) in types.StringTypes:
                 child_result_list.append(child.before + child.after)
-            else: # child.after may have been a TIMEOUT or EOF, so don't cat those.
+            else:
+                # child.after may have been a TIMEOUT or EOF,
+                # which we don't want appended to the list.
                 child_result_list.append(child.before)
             if type(responses[index]) in types.StringTypes:
                 child.send(responses[index])
-            elif type(responses[index]) is types.FunctionType:
+            elif isinstance(responses[index], types.FunctionType):
                 callback_result = responses[index](locals())
                 sys.stdout.flush()
                 if type(callback_result) in types.StringTypes:
                     child.send(callback_result)
                 elif callback_result:
                     break
             else:
-                raise TypeError ('The callback must be a string or function type.')
+                raise TypeError('The callback must be a string or function.')
             event_count = event_count + 1
-        except TIMEOUT, e:
+        except TIMEOUT as e:
             child_result_list.append(child.before)
             break
-        except EOF, e:
+        except EOF as e:
             child_result_list.append(child.before)
             break
     child_result = ''.join(child_result_list)
     if withexitstatus:
         child.close()
         return (child_result, child.exitstatus)
     else:
         return child_result
 
-class spawn (object):
+
+class spawn(object):
 
     """This is the main class interface for Pexpect. Use this class to start
     and control child applications. """
 
-    def __init__(self, command, args=[], timeout=30, maxread=2000, searchwindowsize=None, logfile=None, cwd=None, env=None):
+    def __init__(self, command, args=[], timeout=30, maxread=2000,
+        searchwindowsize=None, logfile=None, cwd=None, env=None):
 
         """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')
+            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'])
+            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 > log_list.txt"')
+            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 > log_list.txt'
+            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.
 
@@ skipping 20 matching lines @@
 
         Example log to stdout::
 
             child = pexpect.spawn('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
 
         To separately log output sent to the child use logfile_send::
-        
+
             self.logfile_send = fout
 
         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.
@@ skipping 28 matching lines @@
 
         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
-        self.status = None # status returned by os.waitpid
+        # status returned by os.waitpid
+        self.status = None
         self.flag_eof = False
         self.pid = None
-        self.child_fd = -1 # initially closed
+        # the chile filedescriptor is initially closed
+        self.child_fd = -1
         self.timeout = timeout
         self.delimiter = EOF
         self.logfile = logfile
-        self.logfile_read = None # input from child (read_nonblocking)
-        self.logfile_send = None # output to send (send, sendline)
-        self.maxread = maxread # max bytes to read at one time into buffer
-        self.buffer = '' # This is the read buffer. See maxread.
-        self.searchwindowsize = searchwindowsize # Anything before searchwindowsize point is preserved, but not searched.
-        # Most Linux machines don't like delaybeforesend to be below 0.03 (30 ms).
-        self.delaybeforesend = 0.05 # Sets sleep time used just before sending data to child. Time in seconds.
-        self.delayafterclose = 0.1 # Sets delay in close() method to allow kernel time to update process status. Time in seconds.
-        self.delayafterterminate = 0.1 # Sets delay in terminate() method to allow kernel time to update process status. Time in seconds.
-        self.softspace = False # File-like object.
-        self.name = '<' + repr(self) + '>' # File-like object.
-        self.encoding = None # File-like object.
-        self.closed = True # File-like object.
+        # 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 = ''
+        # 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.encoding = None
+        self.closed = True
         self.cwd = cwd
         self.env = env
-        self.__irix_hack = (sys.platform.lower().find('irix')>=0) # This flags if we are running on irix
+        # This flags if we are running on irix
+        self.__irix_hack = (sys.platform.lower().find('irix') >= 0)
         # Solaris uses internal __fork_pty(). All others use pty.fork().
-        if (sys.platform.lower().find('solaris')>=0) or (sys.platform.lower().find('sunos5')>=0):
+        if ((sys.platform.lower().find('solaris') >= 0)
+            or (sys.platform.lower().find('sunos5') >= 0)):
             self.use_native_pty_fork = False
         else:
             self.use_native_pty_fork = True
 
-
-        # allow dummy instances for subclasses that may not use command or args.
+        # 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)
+            self._spawn(command, args)
 
     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.
             # -- Fernando Perez
             try:
                 self.close()
-            except AttributeError:
+            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__ + ' (' + __revision__ + ')')
@@ skipping 16 matching lines @@
         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=[]):
+    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 haved spawned a child
+        # 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 type(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 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 type (args) != type([]):
-            raise TypeError ('The argument, args, must be a list.')
+        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:
-            self.args = args[:] # work with a copy
-            self.args.insert (0, command)
+            # 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)
+            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) + '>'
+        self.name = '<' + ' '.join(self.args) + '>'
 
-        assert self.pid is None, 'The pid member should be None.'
-        assert self.command is not None, 'The command member should not be None.'
+        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, e:
-                raise ExceptionPexpect('Error! pty.fork() failed: ' + str(e))
-        else: # Use internal __fork_pty
+            except OSError as e:
+                raise ExceptionPexpect('pty.fork() failed: ' + str(e))
+        else:
+            # Use internal __fork_pty
             self.pid, self.child_fd = self.__fork_pty()
 
-        if self.pid == 0: # Child
+        if self.pid == 0:
+            # Child
             try:
-                self.child_fd = sys.stdout.fileno() # used by setwinsize()
+                # used by setwinsize()
+                self.child_fd = sys.stdout.fileno()
                 self.setwinsize(24, 80)
             except:
                 # Some platforms do not like setwinsize (Cygwin).
                 # This will cause problem when running applications that
                 # are very picky about window size.
                 # This is a serious limitation, but not a show stopper.
                 pass
             # Do not allow child to inherit open file descriptors from parent.
             max_fd = resource.getrlimit(resource.RLIMIT_NOFILE)[0]
-            for i in range (3, max_fd):
+            for i in range(3, max_fd):
                 try:
-                    os.close (i)
+                    os.close(i)
                 except OSError:
                     pass
 
             # I don't know why this works, but ignoring SIGHUP fixes a
             # problem when trying to start a Java daemon with sudo
             # (specifically, Tomcat).
             signal.signal(signal.SIGHUP, signal.SIG_IGN)
 
             if self.cwd is not None:
                 os.chdir(self.cwd)
@@ skipping 16 matching lines @@
         resolve the issue with Python's pty.fork() not supporting Solaris,
         particularly ssh. Based on patch to posixmodule.c authored by Noah
         Spurrier::
 
             http://mail.python.org/pipermail/python-dev/2003-May/035281.html
 
         """
 
         parent_fd, child_fd = os.openpty()
         if parent_fd < 0 or child_fd < 0:
-            raise ExceptionPexpect, "Error! Could not open pty with os.openpty()."
+            raise ExceptionPexpect("Could not open with os.openpty().")
 
         pid = os.fork()
         if pid < 0:
-            raise ExceptionPexpect, "Error! Failed os.fork()."
+            raise ExceptionPexpect("Failed os.fork().")
         elif pid == 0:
             # Child.
             os.close(parent_fd)
             self.__pty_make_controlling_tty(child_fd)
 
             os.dup2(child_fd, 0)
             os.dup2(child_fd, 1)
             os.dup2(child_fd, 2)
 
             if child_fd > 2:
                 os.close(child_fd)
         else:
             # Parent.
             os.close(child_fd)
 
         return pid, parent_fd
 
     def __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 still connected.
-        fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY);
-        if fd >= 0:
-            os.close(fd)
+        # Disconnect from controlling tty. Harmless if not already connected.
+        try:
+            fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
+            if fd >= 0:
+                os.close(fd)
+        except:
+            # Already disconnected. This happens if running inside cron.
+            pass
 
         os.setsid()
 
         # Verify we are disconnected from controlling tty
+        # by attempting to open it again.
         try:
-            fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY);
+            fd = os.open("/dev/tty", os.O_RDWR | os.O_NOCTTY)
             if fd >= 0:
                 os.close(fd)
-                raise ExceptionPexpect, "Error! We are not disconnected from a controlling tty."
+                raise ExceptionPexpect('Failed to disconnect from ' +
+                    'controlling tty. It is still possible to open /dev/tty.')
         except:
             # Good! We are disconnected from a controlling tty.
             pass
 
         # Verify we can open child pty.
-        fd = os.open(child_name, os.O_RDWR);
+        fd = os.open(child_name, os.O_RDWR)
         if fd < 0:
-            raise ExceptionPexpect, "Error! Could not open child pty, " + child_name
+            raise ExceptionPexpect("Could not open child pty, " + child_name)
         else:
             os.close(fd)
 
         # Verify we now have a controlling tty.
         fd = os.open("/dev/tty", os.O_WRONLY)
         if fd < 0:
-            raise ExceptionPexpect, "Error! Could not open controlling tty, /dev/tty"
+            raise ExceptionPexpect("Could not open controlling tty, /dev/tty")
         else:
             os.close(fd)
 
-    def fileno (self):   # File-like object.
+    def fileno(self):
 
         """This returns the file descriptor of the pty for the child.
         """
 
         return self.child_fd
 
-    def close (self, force=True):   # File-like object.
+    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)
-            time.sleep(self.delayafterclose) # Give kernel time to update process status.
+            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 ('close() could not terminate the child using terminate()')
+                    raise ExceptionPexpect('Could not terminate the child.')
             self.child_fd = -1
             self.closed = True
             #self.pid = None
 
-    def flush (self):   # File-like object.
+    def flush(self):
 
         """This does nothing. It is here to support the interface for a
         File-like object. """
 
         pass
 
-    def isatty (self):   # File-like object.
+    def isatty(self):
 
         """This returns True if the file descriptor is open and connected to a
         tty(-like) device, else False. """
 
         return os.isatty(self.child_fd)
 
-    def waitnoecho (self, timeout=-1):
+    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 = pexpect.spawn('ssh user@example.com')
             p.waitnoecho()
             p.sendline(mypassword)
 
-        If timeout is None then this method to block forever until ECHO flag is
-        False.
-
+        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 
+            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):
+    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(). """
 
         attr = termios.tcgetattr(self.child_fd)
         if attr[3] & termios.ECHO:
             return True
         return False
 
-    def setecho (self, state):
+    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')
-            p.sendline ('1234') # We will see this twice (once from tty echo and again from cat).
-            p.expect (['1234'])
-            p.expect (['1234'])
+            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'])
+            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') # We will see this twice (once from tty echo and again from 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'])
+            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'])
         """
 
         self.child_fd
         attr = termios.tcgetattr(self.child_fd)
         if state:
             attr[3] = attr[3] | termios.ECHO
         else:
             attr[3] = attr[3] & ~termios.ECHO
-        # I tried TCSADRAIN and TCSAFLUSH, but these were inconsistent
-        # and blocked on some platforms. TCSADRAIN is probably ideal if it worked.
+        # I tried TCSADRAIN and TCSAFLUSH, but
+        # these were inconsistent and blocked on some platforms.
+        # TCSADRAIN would probably be ideal if it worked.
         termios.tcsetattr(self.child_fd, termios.TCSANOW, attr)
 
-    def read_nonblocking (self, size = 1, timeout = -1):
+    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 was no data immediately ready then this will raise
-        a TIMEOUT exception.
+        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 in read_nonblocking().')
+            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():
-            r,w,e = self.__select([self.child_fd], [], [], 0) # timeout of 0 means "poll"
+            # 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) in read_nonblocking(). Braindead platform.')
+                raise EOF('End Of File (EOF). Braindead platform.')
         elif self.__irix_hack:
-            # This is a hack for Irix. It seems that Irix requires a long delay before checking isalive.
-            # This adds a 2 second delay, but only when the child is terminated.
+            # 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) in read_nonblocking(). Pokey platform.')
+                raise EOF('End Of File (EOF). Slow platform.')
 
-        r,w,e = self.__select([self.child_fd], [], [], timeout)
+        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;
-                # then timeout on the select; and then finally admit that they are not alive.
+                # 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) in read_nonblocking(). Very pokey platform.')
+                raise EOF('End of File (EOF). Very slow platform.')
             else:
-                raise TIMEOUT ('Timeout exceeded in read_nonblocking().')
+                raise TIMEOUT('Timeout exceeded.')
 
         if self.child_fd in r:
             try:
                 s = os.read(self.child_fd, size)
-            except OSError, e: # Linux does this
+            except OSError as e:
+                # Linux does this
                 self.flag_eof = True
-                raise EOF ('End Of File (EOF) in read_nonblocking(). Exception style platform.')
-            if s == '': # BSD style
+                raise EOF('End Of File (EOF). Exception style platform.')
+            if s == '':
+                # BSD style
                 self.flag_eof = True
-                raise EOF ('End Of File (EOF) in read_nonblocking(). Empty string style platform.')
-
+                raise EOF('End Of File (EOF). Empty string style platform.')
             if self.logfile is not None:
-                self.logfile.write (s)
+                self.logfile.write(s)
                 self.logfile.flush()
             if self.logfile_read is not None:
-                self.logfile_read.write (s)
+                self.logfile_read.write(s)
                 self.logfile_read.flush()
-
             return s
 
-        raise ExceptionPexpect ('Reached an unexpected state in read_nonblocking().')
+        raise ExceptionPexpect('Reached an unexpected state.')
 
-    def read (self, size = -1):   # File-like object.
+    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 ''
         if size < 0:
-            self.expect (self.delimiter) # delimiter default is EOF
+            # 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('.{%d}' % size, re.DOTALL)
-        index = self.expect ([cre, self.delimiter]) # delimiter default is EOF
+        # delimiter default is EOF
+        index = self.expect([cre, self.delimiter])
         if index == 0:
-            return self.after ### self.before should be ''. Should I assert this?
+            ### FIXME self.before should be ''. Should I assert this?
+            return self.after
         return self.before
 
-    def readline (self, size = -1):    # File-like object.
+    def readline(self, size=-1):
 
-        """This reads and returns one entire line. A trailing newline is kept
-        in the string, but may be absent when a file ends with an incomplete
-        line. Note: This readline() looks for a \\r\\n pair even on UNIX
-        because this is what the pseudo tty device returns. So contrary to what
-        you may expect you will receive the newline as \\r\\n. An empty string
-        is returned when EOF is hit immediately. Currently, the size argument is
-        mostly ignored, so this behavior is not standard for a file-like
-        object. If size is 0 then an empty string is returned. """
+        """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 ''
-        index = self.expect (['\r\n', self.delimiter]) # delimiter default is EOF
+        # delimiter default is EOF
+        index = self.expect(['\r\n', self.delimiter])
         if index == 0:
             return self.before + '\r\n'
         else:
             return self.before
 
-    def __iter__ (self):    # File-like object.
+    def __iter__(self):
 
         """This is to support iterators over a file-like object.
         """
 
         return self
 
-    def next (self):    # File-like object.
+    def __next__(self):
 
         """This is to support iterators over a file-like object.
         """
 
         result = self.readline()
         if result == "":
             raise StopIteration
         return result
 
-    def readlines (self, sizehint = -1):    # File-like object.
+    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. """
+        the lines thus read. The optional 'sizehint' argument is ignored. """
 
         lines = []
         while True:
             line = self.readline()
             if not line:
                 break
             lines.append(line)
         return lines
 
-    def write(self, s):   # File-like object.
+    def write(self, s):
 
         """This is similar to send() except that there is no return value.
         """
 
-        self.send (s)
+        self.send(s)
 
-    def writelines (self, sequence):   # File-like object.
+    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)
+            self.write(s)
 
     def send(self, s):
 
         """This sends a string to the child process. This returns the number of
         bytes written. If a log file was set then the data is also written to
         the log. """
 
         time.sleep(self.delaybeforesend)
         if self.logfile is not None:
-            self.logfile.write (s)
+            self.logfile.write(s)
             self.logfile.flush()
         if self.logfile_send is not None:
-            self.logfile_send.write (s)
+            self.logfile_send.write(s)
             self.logfile_send.flush()
-        c = os.write(self.child_fd, s)
+        c = os.write(self.child_fd, s.encode("utf-8"))
         return c
 
     def sendline(self, s=''):
 
-        """This is like send(), but it adds a line feed (os.linesep). This
+        """This is like send(), but it adds a linefeed (os.linesep). This
         returns the number of bytes written. """
 
         n = self.send(s)
-        n = n + self.send (os.linesep)
+        n = n + self.send(os.linesep)
         return n
 
     def sendcontrol(self, char):
 
         """This sends a control character to the child such as Ctrl-C or
         Ctrl-D. For example, to send a Ctrl-G (ASCII 7)::
 
             child.sendcontrol('g')
 
         See also, sendintr() and sendeof().
         """
 
         char = char.lower()
         a = ord(char)
-        if a>=97 and a<=122:
+        if a >= 97 and a <= 122:
             a = a - ord('a') + 1
-            return self.send (chr(a))
-        d = {'@':0, '`':0,
-            '[':27, '{':27,
-            '\\':28, '|':28,
-            ']':29, '}': 29,
-            '^':30, '~':30,
-            '_':31,
-            '?':127}
+            return self.send(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 (chr(d[char]))
+        return self.send(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. """
 
         ### Hmmm... how do I send an EOF?
         ###C  if ((m = write(pty, *buf, p - *buf)) < 0)
         ###C      return (errno == EWOULDBLOCK) ? n : -1;
         #fd = sys.stdin.fileno()
         #old = termios.tcgetattr(fd) # remember current state
         #attr = termios.tcgetattr(fd)
-        #attr[3] = attr[3] | termios.ICANON # ICANON must be set to recognize EOF
+        #attr[3] = attr[3] | termios.ICANON # ICANON must be set to see EOF
         #try: # use try/finally to ensure state gets restored
         #    termios.tcsetattr(fd, termios.TCSADRAIN, attr)
         #    if hasattr(termios, 'CEOF'):
-        #        os.write (self.child_fd, '%c' % termios.CEOF)
+        #        os.write(self.child_fd, '%c' % termios.CEOF)
         #    else:
         #        # Silly platform does not define CEOF so assume CTRL-D
-        #        os.write (self.child_fd, '%c' % 4)
+        #        os.write(self.child_fd, '%c' % 4)
         #finally: # restore state
         #    termios.tcsetattr(fd, termios.TCSADRAIN, old)
         if hasattr(termios, 'VEOF'):
             char = termios.tcgetattr(self.child_fd)[6][termios.VEOF]
         else:
             # platform does not define VEOF so assume CTRL-D
             char = chr(4)
         self.send(char)
 
     def sendintr(self):
 
         """This sends a SIGINT to the child. It does not require
         the SIGINT to be the first character on a line. """
 
         if hasattr(termios, 'VINTR'):
             char = termios.tcgetattr(self.child_fd)[6][termios.VINTR]
         else:
             # platform does not define VINTR so assume CTRL-C
             char = chr(3)
-        self.send (char)
+        self.send(char)
 
-    def eof (self):
+    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
@@ skipping 16 matching lines @@
             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, e:
+        except OSError as e:
             # 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, technically, the child
-        is still alive until its output is read. """
+        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.')
+            raise ExceptionPexpect('Cannot wait for dead child process.')
         self.exitstatus = os.WEXITSTATUS(status)
-        if os.WIFEXITED (status):
+        if os.WIFEXITED(status):
             self.status = status
             self.exitstatus = os.WEXITSTATUS(status)
             self.signalstatus = None
             self.terminated = True
-        elif os.WIFSIGNALED (status):
+        elif os.WIFSIGNALED(status):
             self.status = status
             self.exitstatus = None
             self.signalstatus = os.WTERMSIG(status)
             self.terminated = True
-        elif os.WIFSTOPPED (status):
-            raise ExceptionPexpect ('Wait was called for a child process that is stopped. This is not supported. Is some other process attempting job control with our child pid?')
+        elif os.WIFSTOPPED(status):
+            # 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
-            # status of a defunct process. This is super-lame. The flag_eof would have
-            # been set in read_nonblocking(), so this should be safe.
+            # This is for Linux, which requires the blocking form
+            # of waitpid to # get 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, e: # No child processes
+        except OSError as e:
+            # No child processes
             if e[0] == 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?')
+                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 e
 
-        # 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.
+        # 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:
-                pid, status = os.waitpid(self.pid, waitpid_options) ### os.WNOHANG) # Solaris!
-            except OSError, e: # This should never happen...
+                ### os.WNOHANG) # Solaris!
+                pid, status = os.waitpid(self.pid, waitpid_options)
+            except OSError as e:
+                # This should never happen...
                 if e[0] == errno.ECHILD:
-                    raise ExceptionPexpect ('isalive() encountered condition that should never happen. There was no child process. Did someone else call waitpid() on our process?')
+                    raise ExceptionPexpect('isalive() encountered condition ' +
+                            'that should never happen. There was no child ' +
+                            'process. Did someone else call waitpid() ' +
+                            'on our process?')
                 else:
                     raise e
 
-            # 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 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):
+        if os.WIFEXITED(status):
             self.status = status
             self.exitstatus = os.WEXITSTATUS(status)
             self.signalstatus = None
             self.terminated = True
-        elif os.WIFSIGNALED (status):
+        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?')
+        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():
@@ skipping 19 matching lines @@
 
              cpl = self.compile_pattern_list(my_pattern)
              while some_condition:
                 ...
                 i = self.expect_list(clp, timeout)
                 ...
         """
 
         if patterns is None:
             return []
-        if type(patterns) is not types.ListType:
+        if not isinstance(patterns, list):
             patterns = [patterns]
 
-        compile_flags = re.DOTALL # Allow dot to match \n
+        # Allow dot to match \n
+        compile_flags = re.DOTALL
         if self.ignorecase:
             compile_flags = compile_flags | re.IGNORECASE
         compiled_pattern_list = []
         for p in patterns:
             if type(p) in types.StringTypes:
                 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 type(p) is type(re.compile('')):
+            elif isinstance(p, type(re.compile(''))):
                 compiled_pattern_list.append(p)
             else:
-                raise TypeError ('Argument must be one of StringTypes, EOF, TIMEOUT, SRE_Pattern, or a list of those type. %s' % str(type(p)))
+                raise TypeError('Argument must be one of StringTypes, ' +
+                        'EOF, TIMEOUT, SRE_Pattern, or a list of those ' +
+                        'type. %s' % str(type(p)))
 
         return compiled_pattern_list
 
-    def expect(self, pattern, timeout = -1, searchwindowsize=None):
+    def expect(self, pattern, timeout=-1, searchwindowsize=-1):
 
         """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::
+        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
+            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
+            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])
+                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'])
+                    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)
+                p.expect(pexpect.EOF)
                 print p.before
 
         If you are trying to optimize for speed then see expect_list().
         """
 
         compiled_pattern_list = self.compile_pattern_list(pattern)
-        return self.expect_list(compiled_pattern_list, timeout, searchwindowsize)
+        return self.expect_list(compiled_pattern_list,
+                timeout, searchwindowsize)
 
-    def expect_list(self, pattern_list, timeout = -1, searchwindowsize = -1):
+    def expect_list(self, pattern_list, timeout=-1, searchwindowsize=-1):
 
         """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
+        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. """
 
-        return self.expect_loop(searcher_re(pattern_list), timeout, searchwindowsize)
+        return self.expect_loop(searcher_re(pattern_list),
+                timeout, searchwindowsize)
 
-    def expect_exact(self, pattern_list, timeout = -1, searchwindowsize = -1):
+    def expect_exact(self, pattern_list, timeout=-1, searchwindowsize=-1):
 
         """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."""
 
-        if type(pattern_list) in types.StringTypes or pattern_list in (TIMEOUT, EOF):
+        if (type(pattern_list) in types.StringTypes or
+            pattern_list in (TIMEOUT, EOF)):
             pattern_list = [pattern_list]
-        return self.expect_loop(searcher_string(pattern_list), timeout, searchwindowsize)
+        return self.expect_loop(searcher_string(pattern_list),
+                timeout, searchwindowsize)
 
-    def expect_loop(self, searcher, timeout = -1, searchwindowsize = -1):
+    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.
+        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. """
 
         self.searcher = searcher
 
         if timeout == -1:
             timeout = self.timeout
         if timeout is not None:
-            end_time = time.time() + timeout 
+            end_time = time.time() + timeout
         if searchwindowsize == -1:
             searchwindowsize = self.searchwindowsize
 
         try:
             incoming = self.buffer
             freshlen = len(incoming)
-            while True: # Keep reading until exception or return.
+            while True:
+                # Keep reading until exception or return.
                 index = searcher.search(incoming, freshlen, searchwindowsize)
                 if index >= 0:
-                    self.buffer = incoming[searcher.end : ]
-                    self.before = incoming[ : searcher.start]
-                    self.after = incoming[searcher.start : searcher.end]
+                    self.buffer = incoming[searcher.end:]
+                    self.before = incoming[: searcher.start]
+                    self.after = incoming[searcher.start: searcher.end]
                     self.match = searcher.match
                     self.match_index = index
                     return self.match_index
                 # No match at this point
                 if timeout < 0 and timeout is not None:
-                    raise TIMEOUT ('Timeout exceeded in expect_any().')
+                    raise TIMEOUT('Timeout exceeded in expect_any().')
                 # Still have time left, so read more data
-                c = self.read_nonblocking (self.maxread, timeout)
+                c = self.read_nonblocking(self.maxread, timeout)
                 freshlen = len(c)
-                time.sleep (0.0001)
+                time.sleep(0.0001)
                 incoming = incoming + c
                 if timeout is not None:
                     timeout = end_time - time.time()
-        except EOF, e:
+        except EOF as e:
             self.buffer = ''
             self.before = incoming
             self.after = EOF
             index = searcher.eof_index
             if index >= 0:
                 self.match = EOF
                 self.match_index = index
                 return self.match_index
             else:
                 self.match = None
                 self.match_index = None
-                raise EOF (str(e) + '\n' + str(self))
-        except TIMEOUT, e:
+                raise EOF(str(e) + '\n' + str(self))
+        except TIMEOUT as e:
             self.buffer = incoming
             self.before = incoming
             self.after = TIMEOUT
             index = searcher.timeout_index
             if index >= 0:
                 self.match = TIMEOUT
                 self.match_index = index
                 return self.match_index
             else:
                 self.match = None
                 self.match_index = None
-                raise TIMEOUT (str(e) + '\n' + str(self))
+                raise TIMEOUT(str(e) + '\n' + str(self))
         except:
             self.before = incoming
             self.after = None
             self.match = None
             self.match_index = None
             raise
 
     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', 1074295912L)
+        TIOCGWINSZ = getattr(termios, 'TIOCGWINSZ', 1074295912)
         s = struct.pack('HHHH', 0, 0, 0, 0)
         x = fcntl.ioctl(self.fileno(), TIOCGWINSZ, s)
         return struct.unpack('HHHH', x)[0:2]
 
-    def setwinsize(self, r, c):
+    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. """
 
         # Check for buggy platforms. Some Python versions on some platforms
         # (notably OSF1 Alpha and RedHat 7.1) truncate the value for
         # termios.TIOCSWINSZ. It is not clear why this happens.
         # These platforms don't seem to handle the signed int very well;
         # yet other platforms like OpenBSD have a large negative value for
         # TIOCSWINSZ and they don't have a truncate problem.
         # Newer versions of Linux have totally different values for TIOCSWINSZ.
         # Note that this fix is a hack.
         TIOCSWINSZ = getattr(termios, 'TIOCSWINSZ', -2146929561)
-        if TIOCSWINSZ == 2148037735L: # L is not required in Python >= 2.2.
-            TIOCSWINSZ = -2146929561 # Same bits, but with sign.
+        if TIOCSWINSZ == 2148037735:
+            # Same bits, but with sign.
+            TIOCSWINSZ = -2146929561
         # Note, assume ws_xpixel and ws_ypixel are zero.
-        s = struct.pack('HHHH', r, c, 0, 0)
+        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):
+    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))
+                a = struct.unpack('hhhh', fcntl.ioctl(sys.stdout.fileno(),
+                    termios.TIOCGWINSZ , s))
                 global p
                 p.setwinsize(a[0],a[1])
-            p = pexpect.spawn('/bin/bash') # Note this is global and used in sigwinch_passthrough.
+            # 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.stdout.write (self.buffer)
+        self.stdout.write(self.buffer)
         self.stdout.flush()
         self.buffer = ''
         mode = tty.tcgetattr(self.STDIN_FILENO)
         tty.setraw(self.STDIN_FILENO)
         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 != '' 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):
+    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], [], [])
+            r, w, e = self.__select([self.child_fd, self.STDIN_FILENO], [], [])
             if self.child_fd in r:
                 data = self.__interact_read(self.child_fd)
-                if output_filter: data = output_filter(data)
+                if output_filter:
+                    data = output_filter(data)
                 if self.logfile is not None:
-                    self.logfile.write (data)
+                    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)
+                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):
+    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, e:
+                return select.select(iwtd, owtd, ewtd, timeout)
+            except select.error as e:
                 if e[0] == errno.EINTR:
-                    # if we loop back we have to subtract the amount of time we already waited.
+                    # 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 really is an exception
+                            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):
+    def setmaxread(self, maxread):
 
         """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.')
+        raise ExceptionPexpect('This method is no longer supported ' +
+                'or allowed. Just assign a value to the ' +
+                'maxread member variable.')
 
-    def setlog (self, fileobject):
+    def setlog(self, fileobject):
 
         """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.')
+        raise ExceptionPexpect('This method is no longer supported ' +
+                'or allowed. Just assign a value to the logfile ' +
+                'member variable.')
 
 ##############################################################################
 # End of spawn class
 ##############################################################################
 
-class searcher_string (object):
+
+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 zip(range(len(strings)), strings):
+        for n, s in zip(list(range(len(strings))), 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:'))
+        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))
+            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.append((self.timeout_index,
+                '    %d: TIMEOUT' % self.timeout_index))
         ss.sort()
         ss = 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.
@@ skipping 10 matching lines @@
         # 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))
+                offset = -(freshlen + len(s))
             else:
                 # better obey searchwindowsize
                 offset = -searchwindowsize
             n = buffer.find(s, offset)
             if n >= 0 and n < first_match:
                 first_match = n
                 best_index, best_match = index, s
         if first_match == absurd_match:
             return -1
         self.match = best_match
         self.start = first_match
         self.end = self.start + len(self.match)
         return best_index
 
-class searcher_re (object):
+
+class searcher_re(object):
 
     """This is regular expression string search helper for the
-    spawn.expect_any() method.
+    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(range(len(patterns)), patterns):
+        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,str(s.pattern))) for n,s in self._searches]
-        ss.append((-1,'searcher_re:'))
+        ss = [(n, '    %d: re.compile("%s")' %
+            (n, str(s.pattern))) for n, s in self._searches]
+        ss.append((-1, 'searcher_re:'))
         if self.eof_index >= 0:
-            ss.append ((self.eof_index,'    %d: EOF' % self.eof_index))
+            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.append((self.timeout_index, '    %d: TIMEOUT' %
+                self.timeout_index))
         ss.sort()
         ss = 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."""
 
         absurd_match = len(buffer)
         first_match = absurd_match
         # '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)
+            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 n < first_match:
                 first_match = n
                 the_match = match
                 best_index = index
         if first_match == absurd_match:
             return -1
         self.start = first_match
         self.match = the_match
         self.end = self.match.end()
         return best_index
 
-def which (filename):
+
+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 already contains a path.
+    # Special case where filename contains an explicit path.
     if os.path.dirname(filename) != '':
-        if os.access (filename, os.X_OK):
+        if os.access(filename, os.X_OK):
             return filename
-
-    if not os.environ.has_key('PATH') or os.environ['PATH'] == '':
+    if 'PATH' not in os.environ or os.environ['PATH'] == '':
         p = os.defpath
     else:
         p = os.environ['PATH']
+    pathlist = string.split(p, os.pathsep)
+    for path in pathlist:
+        ff = os.path.join(path, filename)
+        if os.access(ff, os.X_OK):
+            return ff
+    return None
 
-    # Oddly enough this was the one line that made Pexpect
-    # incompatible with Python 1.5.2.
-    #pathlist = p.split (os.pathsep)
-    pathlist = string.split (p, os.pathsep)
-
-    for path in pathlist:
-        f = os.path.join(path, filename)
-        if os.access(f, os.X_OK):
-            return f
-    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
-    state_whitespace = 4 # The state of consuming whitespace between commands.
+    # 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
+            if c == '\\':
+                # Escape the next character
                 state = state_esc
-            elif c == r"'": # Handle single quote
+            elif c == r"'":
+                # Handle single quote
                 state = state_singlequote
-            elif c == r'"': # Handle double quote
+            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:
-                    None # Do nothing.
+                    # 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
 
-# vi:ts=4:sw=4:expandtab:ft=python:
+# vi:set sr et ts=4 sw=4 ft=python :