Table of Contents

• Overview
• run
• spawn

Overview

• Pexpect makes Python a better tool for controlling other applications.
• Pexpect can be used for automating interactive applications

# Specify encoding='utf-8' for Python 3
child = pexpect.spawn('some_command', encoding='utf-8')
# options can be specified both in the constructoror just assigning properties
child.timeout = None        # default is 30s, timout between expect() calls
child.logfile = sys.stdout  # All input and output will be copied to this
child.expect('things')
child.send('things')
# I couldn't find somewhere explicitly documented,
# but it seems like a good thing to call close() explicitly.
child.close()
print(child.exitstatus, child.signalstatus)

run

pexpect.run(command, timeout=30, withexitstatus=False, events=None, extra_args=None, logfile=None, cwd=None, env=None, **kwargs)

• This function runs the given command; waits for it to finish;

import pexpect
pexpect.run('scp foo user@example.com:.', events={'(?i)password': mypassword})

spawn

spawn

class pexpect.spawn(command, args=[], timeout=30, maxread=2000, searchwindowsize=None, logfile=None, cwd=None, env=None, ignore_sighup=False, echo=True, preexec_fn=None, encoding=None, codec_errors='strict', dimensions=None)

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'])

• Pexpect does NOT interpret shell meta characters such as redirect, pipe, or wild cards (>, |, or *)
• To use those things, use one of the shell commands explicitly

child = pexpect.spawn('/bin/bash -c "ls -l | grep LOG > logs.txt"')
child.expect(pexpect.EOF)

expect

expect(pattern, timeout=-1, searchwindowsize=-1, async_=False, **kw)

• This seeks through the stream until a pattern is matched.

# the input is 'foobar'
index = p.expect(['bar', 'foo', 'foobar'])
# returns 1('foo') even though 'foobar' is a "better" match

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

• See exact if you want exact match.

• sendline ::

sendline(s='')

• Wraps send(), sending string s to child process, with os.linesep automatically appended.

• sendcontrol ::

sendcontrol(char)

• Use sendintr or sendeof when sending SIGINT or EOF

• close ::

close(force=True)

If you wish to get the exit status of the child you must call the close() method.