blob: ade20b23dac113ab114463be68dffa8d7080f882 [file] [log] [blame]
"""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 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::'ls -la')
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')
This works even for commands that ask for passwords or other input outside of
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,
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.
Pexpect is free, open source, and all that good stuff.
This license is approved by the OSI and FSF as GPL-compatible.
Copyright (c) 2012, Noah Spurrier <>
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 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__ = '2.6'
__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
def __str__(self):
return str(self.value)
def get_trace(self):
"""This returns an abbreviated stack trace with lines that only concern
the caller. In other words, the stack trace inside the Pexpect module
is not included. """
tblist = traceback.extract_tb(sys.exc_info()[2])
#tblist = filter(self.__filter_not_pexpect, tblist)
tblist = [item for item in tblist if self.__filter_not_pexpect(item)]
tblist = traceback.format_list(tblist)
return ''.join(tblist)
def __filter_not_pexpect(self, trace_list_item):
"""This returns True if list item 0 the string '' in it. """
if trace_list_item[0].find('') == -1:
return True
return False
class EOF(ExceptionPexpect):
"""Raised when EOF is read from a child.
This usually means the child has exited."""
class TIMEOUT(ExceptionPexpect):
"""Raised when a read time exceeds the timeout. """
## """Raised when the pattern match time exceeds the timeout.
## This is different than a read TIMEOUT because the child process may
## give output, thus never give a TIMEOUT, but the output
## may never match a pattern.
## """
##class MAXBUFFER(ExceptionPexpect):
## """Raised when a buffer fills before matching an expected pattern."""
def run(command, timeout=-1, withexitstatus=False, events=None,
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 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
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')
The previous code can be replace with the following::
from pexpect import *
run('scp foo', events={'(?i)password': mypassword})
Start the apache daemon on the local machine::
from pexpect import *
run("/usr/local/apache/bin/apachectl start")
Check in a file using SVN::
from pexpect import *
run("svn ci -m 'automatic commit'")
Run a command and capture exit status::
from pexpect import *
(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 'ls -l'",
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)
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)
child = spawn(command, timeout=timeout, maxread=2000, logfile=logfile,
cwd=cwd, env=env)
if events is not None:
patterns = list(events.keys())
responses = list(events.values())
# This assumes EOF or TIMEOUT will eventually cause run to terminate.
patterns = None
responses = None
child_result_list = []
event_count = 0
while True:
index = child.expect(patterns)
if type(child.after) in types.StringTypes:
child_result_list.append(child.before + child.after)
# child.after may have been a TIMEOUT or EOF,
# which we don't want appended to the list.
if type(responses[index]) in types.StringTypes:
elif isinstance(responses[index], types.FunctionType):
callback_result = responses[index](locals())
if type(callback_result) in types.StringTypes:
elif callback_result:
raise TypeError('The callback must be a string or function.')
event_count = event_count + 1
except TIMEOUT as e:
except EOF as e:
child_result = ''.join(child_result_list)
if withexitstatus:
return (child_result, child.exitstatus)
return child_result
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):
"""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')
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', [''])
child = pexpect.spawn('ls', ['-latr', '/tmp'])
After this the child application will be created and will be ready to
talk to. For normal use, see expect() and send() and sendline().
Remember that Pexpect does NOT interpret shell meta characters such as
redirect, pipe, or wild cards (>, |, or *). This is a common mistake.
If you want to run a command and pipe it through another command then
you must also start a shell. For example::
child = pexpect.spawn('/bin/bash -c "ls -l | grep LOG > logs.txt"')
The second form of spawn (where you pass a list of arguments) is useful
in situations where you wish to spawn a command and pass it its own
argument list. This can make syntax more clear. For example, the
following is equivalent to the previous example::
shell_cmd = 'ls -l | grep LOG > logs.txt'
child = pexpect.spawn('/bin/bash', ['-c', shell_cmd])
The maxread attribute sets the read buffer size. This is maximum number
of bytes that Pexpect will try to read from a TTY at one time. Setting
the maxread size to 1 will turn off buffering. Setting the maxread
value higher may help performance in cases where large amounts of
output are read back from the child. This feature is useful in
conjunction with searchwindowsize.
The searchwindowsize attribute sets the how far back in the incomming
seach buffer Pexpect will search for pattern matches. Every time
Pexpect reads some data from the child it will append the data to the
incomming buffer. The default is to search from the beginning of the
imcomming buffer each time new data is read from the child. But this is
very inefficient if you are running a command that generates a large
amount of data where you want to match The searchwindowsize does not
effect the size of the incomming data buffer. You will still have
access to the full buffer after expect() returns.
The logfile member turns on or off logging. All input and output will
be copied to the given file object. Set logfile to None to stop
logging. This is the default. Set logfile to sys.stdout to echo
everything to standard output. The logfile is flushed after each write.
Example log input and output to a file::
child = pexpect.spawn('some_command')
fout = file('mylog.txt','w')
child.logfile = fout
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.
Normally this wouldn't be a problem when interacting with a human at a
real keyboard. If you introduce a slight delay just before writing then
this seems to clear up the problem. This was such a common problem for
many users that I decided that the default pexpect behavior should be
to sleep just before writing to the child application. 1/20th of a
second (50 ms) seems to be enough to clear up the problem. You can set
delaybeforesend to 0 to return to the old behavior. Most Linux machines
don't like this to be below 0.03. I don't know why.
Note that spawn is clever about finding commands on your path.
It uses the same logic that "which" uses to find executables.
If you wish to get the exit status of the child you must call the
close() method. The exit or signal status of the child will be stored
in self.exitstatus or self.signalstatus. If the child exited normally
then exitstatus will store the exit return code and signalstatus will
be None. If the child was terminated abnormally with a signal then
signalstatus will store the signal value and exitstatus will be None.
If you need more detail you can also read the self.status member which
stores the status returned by os.waitpid. You can interpret this using
self.stdin = sys.stdin
self.stdout = sys.stdout
self.stderr = sys.stderr
self.searcher = None
self.ignorecase = False
self.before = None
self.after = None
self.match = None
self.match_index = None
self.terminated = True
self.exitstatus = None
self.signalstatus = None
# status returned by os.waitpid
self.status = None
self.flag_eof = False = None
# the chile filedescriptor is initially closed
self.child_fd = -1
self.timeout = timeout
self.delimiter = EOF
self.logfile = logfile
# input from child (read_nonblocking)
self.logfile_read = None
# output to send (send, sendline)
self.logfile_send = None
# max bytes to read at one time into buffer
self.maxread = maxread
# This is the read buffer. See maxread.
self.buffer = ''
# 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 = '<' + repr(self) + '>'
self.encoding = None
self.closed = True
self.cwd = cwd
self.env = env
# 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)):
self.use_native_pty_fork = False
self.use_native_pty_fork = True
# Support subclasses that do not use command or args.
if command is None:
self.command = None
self.args = None = '<pexpect factory incomplete>'
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
def __str__(self):
"""This returns a human-readable string that represents the state of
the object. """
s = []
s.append('version: ' + __version__ + ' (' + __revision__ + ')')
s.append('command: ' + str(self.command))
s.append('args: ' + str(self.args))
s.append('searcher: ' + str(self.searcher))
s.append('buffer (last 100 chars): ' + str(self.buffer)[-100:])
s.append('before (last 100 chars): ' + str(self.before)[-100:])
s.append('after: ' + str(self.after))
s.append('match: ' + str(self.match))
s.append('match_index: ' + str(self.match_index))
s.append('exitstatus: ' + str(self.exitstatus))
s.append('flag_eof: ' + str(self.flag_eof))
s.append('pid: ' + str(
s.append('child_fd: ' + str(self.child_fd))
s.append('closed: ' + str(self.closed))
s.append('timeout: ' + str(self.timeout))
s.append('delimiter: ' + str(self.delimiter))
s.append('logfile: ' + str(self.logfile))
s.append('logfile_read: ' + str(self.logfile_read))
s.append('logfile_send: ' + str(self.logfile_send))
s.append('maxread: ' + str(self.maxread))
s.append('ignorecase: ' + str(self.ignorecase))
s.append('searchwindowsize: ' + str(self.searchwindowsize))
s.append('delaybeforesend: ' + str(self.delaybeforesend))
s.append('delayafterclose: ' + str(self.delayafterclose))
s.append('delayafterterminate: ' + str(self.delayafterterminate))
return '\n'.join(s)
def _spawn(self, command, args=[]):
"""This starts the given command in a child process. This does all the
fork/exec type of stuff for a pty. This is called by __init__. If args
is empty then command will be parsed (split on spaces) and args will be
set to parsed arguments. """
# The pid and child_fd of this object get set by this method.
# Note that it is difficult for this method to fail.
# You cannot detect if the child process cannot start.
# So the only way you can tell if the child process started
# or not is to try to read from the file descriptor. If you get
# EOF immediately then it means that the child is already dead.
# That may not necessarily be bad because you may have spawned a child
# that performs some task; creates no stdout output; and then dies.
# If command is an int type then it may represent a file descriptor.
if isinstance(command, type(0)):
raise ExceptionPexpect('Command is an int type. ' +
'If this is a file descriptor then maybe you want to ' +
'use fdpexpect.fdspawn which takes an existing ' +
'file descriptor instead of a command string.')
if not isinstance(args, type([])):
raise TypeError('The argument, args, must be a list.')
if args == []:
self.args = split_command_line(command)
self.command = self.args[0]
# Make a shallow copy of the args list.
self.args = args[:]
self.args.insert(0, command)
self.command = command
command_with_path = which(self.command)
if command_with_path is None:
raise ExceptionPexpect('The command was not found or was not ' +
'executable: %s.' % self.command)
self.command = command_with_path
self.args[0] = self.command = '<' + ' '.join(self.args) + '>'
assert 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.child_fd = pty.fork()
except OSError as e:
raise ExceptionPexpect('pty.fork() failed: ' + str(e))
# Use internal __fork_pty, self.child_fd = self.__fork_pty()
if == 0:
# Child
# used by setwinsize()
self.child_fd = sys.stdout.fileno()
self.setwinsize(24, 80)
# 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.
# 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):
except OSError:
# 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:
if self.env is None:
os.execv(self.command, self.args)
os.execvpe(self.command, self.args, self.env)
# Parent
self.terminated = False
self.closed = False
def __fork_pty(self):
"""This implements a substitute for the forkpty system call. This
should be more portable than the pty.fork() function. Specifically,
this should work on Solaris.
Modified 10.06.05 by Geoff Marshall: Implemented __fork_pty() method to
resolve the issue with Python's pty.fork() not supporting Solaris,
particularly ssh. Based on patch to posixmodule.c authored by Noah
parent_fd, child_fd = os.openpty()
if parent_fd < 0 or child_fd < 0:
raise ExceptionPexpect("Could not open with os.openpty().")
pid = os.fork()
if pid < 0:
raise ExceptionPexpect("Failed os.fork().")
elif pid == 0:
# Child.
os.dup2(child_fd, 0)
os.dup2(child_fd, 1)
os.dup2(child_fd, 2)
if child_fd > 2:
# Parent.
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. Harmless if not already connected.
fd ="/dev/tty", os.O_RDWR | os.O_NOCTTY)
if fd >= 0:
# Already disconnected. This happens if running inside cron.
# Verify we are disconnected from controlling tty
# by attempting to open it again.
fd ="/dev/tty", os.O_RDWR | os.O_NOCTTY)
if fd >= 0:
raise ExceptionPexpect('Failed to disconnect from ' +
'controlling tty. It is still possible to open /dev/tty.')
# Good! We are disconnected from a controlling tty.
# Verify we can open child pty.
fd =, os.O_RDWR)
if fd < 0:
raise ExceptionPexpect("Could not open child pty, " + child_name)
# Verify we now have a controlling tty.
fd ="/dev/tty", os.O_WRONLY)
if fd < 0:
raise ExceptionPexpect("Could not open controlling tty, /dev/tty")
def fileno(self):
"""This returns the file descriptor of the pty for the child.
return self.child_fd
def close(self, force=True):
"""This closes the connection with the child application. Note that
calling close() more than once is valid. This emulates standard Python
behavior with files. Set force to True if you want to make sure that
the child is terminated (SIGKILL is sent if the child ignores SIGHUP
and SIGINT). """
if not self.closed:
# Give kernel time to update process status.
if self.isalive():
if not self.terminate(force):
raise ExceptionPexpect('Could not terminate the child.')
self.child_fd = -1
self.closed = True = None
def flush(self):
"""This does nothing. It is here to support the interface for a
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):
"""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')
If timeout==-1 then this method will use the value in self.timeout.
If timeout==None then this method to block until ECHO flag is False.
if timeout == -1:
timeout = self.timeout
if timeout is not None:
end_time = time.time() + timeout
while True:
if not self.getecho():
return True
if timeout < 0 and timeout is not None:
return False
if timeout is not None:
timeout = end_time - time.time()
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):
"""This sets the terminal echo mode on or off. Note that anything the
child sent before the echo will be lost, so you should be sure that
your input buffer is empty before you call setecho(). For example, the
following will work as expected::
p = pexpect.spawn('cat') # Echo is on by default.
p.sendline('1234') # We expect see this twice from the child...
p.expect(['1234']) # ... once from the tty echo...
p.expect(['1234']) # ... and again from cat itself.
p.setecho(False) # Turn off tty echo
p.sendline('abcd') # We will set this only once (echoed by cat).
p.sendline('wxyz') # We will set this only once (echoed by cat)
The following WILL NOT WORK because the lines sent before the setecho
will be lost::
p = pexpect.spawn('cat')
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)
attr = termios.tcgetattr(self.child_fd)
if state:
attr[3] = attr[3] | termios.ECHO
attr[3] = attr[3] & ~termios.ECHO
# 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):
"""This reads at most size characters from the child application. It
includes a timeout. If the read does not complete within the timeout
period then a TIMEOUT exception is raised. If the end of file is read
then an EOF exception will be raised. If a log file was set using
setlog() then all data will also be written to the log file.
If timeout is None then the read may block indefinitely.
If timeout is -1 then the self.timeout value is used. If timeout is 0
then the child is polled and if there is no data immediately ready
then this will raise a TIMEOUT exception.
The timeout refers only to the amount of time to read at least one
character. This is not effected by the 'size' parameter, so if you call
read_nonblocking(size=100, timeout=30) and only one character is
available right away then one character will be returned immediately.
It will not wait for 30 seconds for another 99 characters to come in.
This is a wrapper around It uses to
implement the timeout. """
if self.closed:
raise ValueError('I/O operation on closed file.')
if timeout == -1:
timeout = self.timeout
# Note that some systems such as Solaris do not give an EOF when
# the child dies. In fact, you can still try to read
# from the child_fd -- it will block forever or until TIMEOUT.
# For this case, I test isalive() before doing any reading.
# If isalive() is false, then I pretend that this is the same as EOF.
if not self.isalive():
# timeout of 0 means "poll"
r, w, e = self.__select([self.child_fd], [], [], 0)
if not r:
self.flag_eof = True
raise EOF('End Of File (EOF). Braindead platform.')
elif self.__irix_hack:
# Irix takes a long time before it realizes a child was terminated.
# FIXME So does this mean Irix systems are forced to always have
# FIXME a 2 second delay when calling read_nonblocking? That sucks.
r, w, e = self.__select([self.child_fd], [], [], 2)
if not r and not self.isalive():
self.flag_eof = True
raise EOF('End Of File (EOF). Slow platform.')
r, w, e = self.__select([self.child_fd], [], [], timeout)
if not r:
if not self.isalive():
# Some platforms, such as Irix, will claim that their
# processes are alive; timeout on the select; and
# then finally admit that they are not alive.
self.flag_eof = True
raise EOF('End of File (EOF). Very slow platform.')
raise TIMEOUT('Timeout exceeded.')
if self.child_fd in r:
s =, size)
except OSError as e:
# Linux does this
self.flag_eof = True
raise EOF('End Of File (EOF). Exception style platform.')
if s == '':
# BSD style
self.flag_eof = True
raise EOF('End Of File (EOF). Empty string style platform.')
if self.logfile is not None:
if self.logfile_read is not None:
return s
raise ExceptionPexpect('Reached an unexpected state.')
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:
# delimiter default is EOF
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)
# delimiter default is EOF
index = self.expect([cre, self.delimiter])
if index == 0:
### FIXME self.before should be ''. Should I assert this?
return self.after
return self.before
def readline(self, size=-1):
"""This reads and returns one entire line. The newline at the end of
line is returned as part of the string, unless the file ends without a
newline. An empty string is returned if EOF is encountered immediately.
This looks for a newline as a CR/LF pair (\\r\\n) even on UNIX because
this is what the pseudotty device returns. So contrary to what you may
expect you will receive newlines as \\r\\n.
If the size argument is 0 then an empty string is returned. In all
other cases the size argument is ignored, which is not standard
behavior for a file-like object. """
if size == 0:
return ''
# delimiter default is EOF
index = self.expect(['\r\n', self.delimiter])
if index == 0:
return self.before + '\r\n'
return self.before
def __iter__(self):
"""This is to support iterators over a file-like object.
return self
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):
"""This reads until EOF using readline() and returns a list containing
the lines thus read. The optional 'sizehint' argument is ignored. """
lines = []
while True:
line = self.readline()
if not line:
return lines
def write(self, s):
"""This is similar to send() except that there is no return value.
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:
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. """
if self.logfile is not None:
if self.logfile_send is not None:
c = os.write(self.child_fd, s.encode("utf-8"))
return c
def sendline(self, s=''):
"""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)
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)::
See also, sendintr() and sendeof().
char = char.lower()
a = ord(char)
if a >= 97 and a <= 122:
a = a - ord('a') + 1
return self.send(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]))
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 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)
# else:
# # Silly platform does not define CEOF so assume CTRL-D
# 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]
# platform does not define VEOF so assume CTRL-D
char = chr(4)
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]
# platform does not define VINTR so assume CTRL-C
char = chr(3)
def eof(self):
"""This returns True if the EOF exception was ever raised.
return self.flag_eof
def terminate(self, force=False):
"""This forces a child process to terminate. It starts nicely with
SIGHUP and SIGINT. If "force" is True then moves onto SIGKILL. This
returns True if the child was terminated. This returns False if the
child could not be terminated. """
if not self.isalive():
return True
if not self.isalive():
return True
if not self.isalive():
return True
if not self.isalive():
return True
if force:
if not self.isalive():
return True
return False
return False
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.
if not self.isalive():
return True
return False
def wait(self):
"""This waits until the child exits. This is a blocking call. This will
not read any data from the child, so this will block forever if the
child has unread output and has terminated. In other words, the child
may have printed output then called exit(), but, the child is
technically still alive until its output is read by the parent. """
if self.isalive():
pid, status = os.waitpid(, 0)
raise ExceptionPexpect('Cannot wait for dead child process.')
self.exitstatus = os.WEXITSTATUS(status)
if os.WIFEXITED(status):
self.status = status
self.exitstatus = os.WEXITSTATUS(status)
self.signalstatus = None
self.terminated = True
elif os.WIFSIGNALED(status):
self.status = status
self.exitstatus = None
self.signalstatus = os.WTERMSIG(status)
self.terminated = True
elif os.WIFSTOPPED(status):
# 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.
waitpid_options = 0
waitpid_options = os.WNOHANG
pid, status = os.waitpid(, waitpid_options)
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 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.
if pid == 0:
### os.WNOHANG) # Solaris!
pid, status = os.waitpid(, 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 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 == 0:
return True
if pid == 0:
return True
if os.WIFEXITED(status):
self.status = status
self.exitstatus = os.WEXITSTATUS(status)
self.signalstatus = None
self.terminated = True
elif os.WIFSIGNALED(status):
self.status = status
self.exitstatus = None
self.signalstatus = os.WTERMSIG(status)
self.terminated = True
elif os.WIFSTOPPED(status):
raise ExceptionPexpect('isalive() encountered condition ' +
'where child process is stopped. This is not ' +
'supported. Is some other process attempting ' +
'job control with our child pid?')
return False
def kill(self, sig):
"""This sends the given signal to the child application. In keeping
with UNIX tradition it has a misleading name. It does not necessarily
kill the child unless you send the right signal. """
# Same as os.kill, but the pid is given for you.
if self.isalive():
os.kill(, sig)
def compile_pattern_list(self, patterns):
"""This compiles a pattern-string or a list of pattern-strings.
Patterns must be a StringType, EOF, TIMEOUT, SRE_Pattern, or a list of
those. Patterns may also be None which results in an empty list (you
might do this if waiting for an EOF or TIMEOUT condition without
expecting any pattern).
This is used by expect() when calling expect_list(). Thus expect() is
nothing more than::
cpl = self.compile_pattern_list(pl)
return self.expect_list(cpl, timeout)
If you are using expect() within a loop it may be more
efficient to compile the patterns first and then call expect_list().
This avoid calls in a loop to compile_pattern_list()::
cpl = self.compile_pattern_list(my_pattern)
while some_condition:
i = self.expect_list(clp, timeout)
if patterns is None:
return []
if not isinstance(patterns, list):
patterns = [patterns]
# Allow dot to match \n
compile_flags = re.DOTALL
if self.ignorecase:
compile_flags = compile_flags | re.IGNORECASE
compiled_pattern_list = []
for p in patterns:
if type(p) in types.StringTypes:
compiled_pattern_list.append(re.compile(p, compile_flags))
elif p is EOF:
elif p is TIMEOUT:
elif isinstance(p, type(re.compile(''))):
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=-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::
# the input is 'foobar'
index = p.expect(['bar', 'foo', 'foobar'])
# returns 1('foo') even though 'foobar' is a "better" match
Please note, however, that buffering can affect this behavior, since
input arrives in unpredictable chunks. For example::
# the input is 'foobar'
index = p.expect(['foobar', 'foo'])
# returns 0('foobar') if all input is available at once,
# but returs 1('foo') if parts of the final 'bar' arrive late
After a match is found the instance attributes 'before', 'after' and
'match' will be set. You can see all the data read before the match in
'before'. You can see the data that was matched in 'after'. The
re.MatchObject used in the re match will be in 'match'. If an error
occurred then 'before' will be set to all the data read so far and
'after' and 'match' will be None.
If timeout is -1 then timeout will be set to the self.timeout value.
A list entry may be EOF or TIMEOUT instead of a string. This will
catch these exceptions and return the index of the list entry instead
of raising the exception. The attribute 'after' will be set to the
exception type. The attribute 'match' will be None. This allows you to
write code like this::
index = p.expect(['good', 'bad', pexpect.EOF, pexpect.TIMEOUT])
if index == 0:
elif index == 1:
elif index == 2:
elif index == 3:
instead of code like this::
index = p.expect(['good', 'bad'])
if index == 0:
elif index == 1:
except EOF:
except TIMEOUT:
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')
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)
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
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)
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
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)):
pattern_list = [pattern_list]
return self.expect_loop(searcher_string(pattern_list),
timeout, searchwindowsize)
def expect_loop(self, searcher, timeout=-1, searchwindowsize=-1):
"""This is the common loop used inside expect. The 'searcher' should be
an instance of searcher_re or searcher_string, which describes how and
what to search for in the input.
See expect() for other arguments, return value and exceptions. """
self.searcher = searcher
if timeout == -1:
timeout = self.timeout
if timeout is not None:
end_time = time.time() + timeout
if searchwindowsize == -1:
searchwindowsize = self.searchwindowsize
incoming = self.buffer
freshlen = len(incoming)
while True:
# Keep reading until exception or return.
index =, freshlen, searchwindowsize)
if index >= 0:
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().')
# Still have time left, so read more data
c = self.read_nonblocking(self.maxread, timeout)
freshlen = len(c)
incoming = incoming + c
if timeout is not None:
timeout = end_time - time.time()
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
self.match = None
self.match_index = None
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
self.match = None
self.match_index = None
raise TIMEOUT(str(e) + '\n' + str(self))
self.before = incoming
self.after = None
self.match = None
self.match_index = None
def getwinsize(self):
"""This returns the terminal window size of the child tty. The return
value is a tuple of (rows, cols). """
TIOCGWINSZ = getattr(termios, 'TIOCGWINSZ', 1074295912)
s = struct.pack('HHHH', 0, 0, 0, 0)
x = fcntl.ioctl(self.fileno(), TIOCGWINSZ, s)
return struct.unpack('HHHH', x)[0:2]
def setwinsize(self, rows, cols):
"""This sets the terminal window size of the child tty. This will cause
a SIGWINCH signal to be sent to the child. This does not change the
physical window size. It changes the size reported to TTY-aware
applications like vi or curses -- applications that respond to the
SIGWINCH signal. """
# 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 == 2148037735:
# Same bits, but with sign.
TIOCSWINSZ = -2146929561
# Note, assume ws_xpixel and ws_ypixel are zero.
s = struct.pack('HHHH', rows, cols, 0, 0)
fcntl.ioctl(self.fileno(), TIOCSWINSZ, s)
def interact(self, escape_character=chr(29),
input_filter=None, output_filter=None):
"""This gives control of the child process to the interactive user (the
human at the keyboard). Keystrokes are sent to the child process, and
the stdout and stderr output of the child process is printed. This
simply echos the child stdout and child stderr to the real stdout and
it echos the real stdin to the child stdin. When the user types the
escape_character this method will stop. The default for
escape_character is ^]. This should not be confused with ASCII 27 --
the ESC character. ASCII 29 was chosen for historical merit because
this is the character used by 'telnet' as the escape character. The
escape_character will not be sent to the child process.
You may pass in optional input and output filter functions. These
functions should take a string and return a string. The output_filter
will be passed all the output from the child process. The input_filter
will be passed all the keyboard input from the user. The input_filter
is run BEFORE the check for the escape_character.
Note that if you change the window size of the parent the SIGWINCH
signal will not be passed through to the child. If you want the child
window size to change when the parent's window size changes then do
something like the following example::
import pexpect, struct, fcntl, termios, signal, sys
def sigwinch_passthrough (sig, data):
s = struct.pack("HHHH", 0, 0, 0, 0)
a = struct.unpack('hhhh', fcntl.ioctl(sys.stdout.fileno(),
termios.TIOCGWINSZ , s))
global p
# Note this 'p' global and used in sigwinch_passthrough.
p = pexpect.spawn('/bin/bash')
signal.signal(signal.SIGWINCH, sigwinch_passthrough)
# Flush the buffer.
self.buffer = ''
mode = tty.tcgetattr(self.STDIN_FILENO)
self.__interact_copy(escape_character, input_filter, output_filter)
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, 1000)
def __interact_copy(self, escape_character=None,
input_filter=None, output_filter=None):
"""This is used by the interact() method.
while self.isalive():
r, w, e = self.__select([self.child_fd, self.STDIN_FILENO], [], [])
if self.child_fd in r:
data = self.__interact_read(self.child_fd)
if output_filter:
data = output_filter(data)
if self.logfile is not None:
os.write(self.STDOUT_FILENO, data)
if self.STDIN_FILENO in r:
data = self.__interact_read(self.STDIN_FILENO)
if input_filter:
data = input_filter(data)
i = data.rfind(escape_character)
if i != -1:
data = data[:i]
self.__interact_writen(self.child_fd, data)
self.__interact_writen(self.child_fd, data)
def __select(self, iwtd, owtd, ewtd, timeout=None):
"""This is a wrapper around that ignores signals. If 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:
return, 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 timeout is not None:
timeout = end_time - time.time()
if timeout < 0:
return([], [], [])
# something else caused the select.error, so
# this actually is an exception.
# The following methods are no longer supported or allowed.
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.')
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.')
# End of spawn class
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.
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(list(range(len(strings))), strings):
if s is EOF:
self.eof_index = n
if s is TIMEOUT:
self.timeout_index = n
self._strings.append((n, s))
def __str__(self):
"""This returns a human-readable string that represents the state of
the object."""
ss = [(ns[0], ' %d: "%s"' % ns) for ns in self._strings]
ss.append((-1, 'searcher_string:'))
if self.eof_index >= 0:
ss.append((self.eof_index, ' %d: EOF' % self.eof_index))
if self.timeout_index >= 0:
' %d: TIMEOUT' % self.timeout_index))
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.
See class spawn for the 'searchwindowsize' argument.
If there is a match this returns the index of that string, and sets
'start', 'end' and 'match'. Otherwise, this returns -1. """
absurd_match = len(buffer)
first_match = absurd_match
# 'freshlen' helps a lot here. Further optimizations could
# possibly include:
# using something like the Boyer-Moore Fast String Searching
# Algorithm; pre-compiling the search through a list of
# strings into something that can scan the input once to
# search for all N strings; realize that if we search for
# ['bar', 'baz'] and the input is '' 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))
# 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):
"""This is regular expression string search helper for the
spawn.expect_any() method. This helper class is for powerful
pattern matching. For speed, see the helper class, searcher_string.
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
def __init__(self, patterns):
"""This creates an instance that searches for 'patterns' Where
'patterns' may be a list or other sequence of compiled regular
expressions, or the EOF or TIMEOUT types."""
self.eof_index = -1
self.timeout_index = -1
self._searches = []
for n, s in zip(list(range(len(patterns))), patterns):
if s is EOF:
self.eof_index = n
if s is TIMEOUT:
self.timeout_index = n
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:'))
if self.eof_index >= 0:
ss.append((self.eof_index, ' %d: EOF' % self.eof_index))
if self.timeout_index >= 0:
ss.append((self.timeout_index, ' %d: TIMEOUT' %
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
searchstart = max(0, len(buffer) - searchwindowsize)
for index, s in self._searches:
match =, searchstart)
if match is None:
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):
"""This takes a given filename; tries to find it in the environment path;
then checks if it is executable. This returns the full path to the filename
if found and executable. Otherwise this returns None."""
# Special case where filename contains an explicit path.
if os.path.dirname(filename) != '':
if os.access(filename, os.X_OK):
return filename
if 'PATH' not in os.environ or os.environ['PATH'] == '':
p = os.defpath
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
def split_command_line(command_line):
"""This splits a command line into a list of arguments. It splits arguments
on spaces, but handles embedded quotes, doublequotes, and escaped
characters. It's impossible to do this with a regular expression, so I
wrote a little state machine to parse the command line. """
arg_list = []
arg = ''
# Constants to name the states we can be in.
state_basic = 0
state_esc = 1
state_singlequote = 2
state_doublequote = 3
# The state when consuming whitespace between commands.
state_whitespace = 4
state = state_basic
for c in command_line:
if state == state_basic or state == state_whitespace:
if c == '\\':
# Escape the next character
state = state_esc
elif c == r"'":
# Handle single quote
state = state_singlequote
elif c == r'"':
# Handle double quote
state = state_doublequote
elif c.isspace():
# Add arg to arg_list if we aren't in the middle of whitespace.
if state == state_whitespace:
# Do nothing.
arg = ''
state = state_whitespace
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
arg = arg + c
elif state == state_doublequote:
if c == r'"':
state = state_basic
arg = arg + c
if arg != '':
return arg_list
# vi:set sr et ts=4 sw=4 ft=python :