Re: [Tutor] Pexpect maxread & searchwindowsize, timeout
Thanks! That solves my question about configuring the timeout value.
However - I still have the problem (I believe) that by default, I can
handle all the output. When I issue the "show version" it fails, but
if I issue a command with less data returned it succeeds.
In the documentation I can see that pexpect uses a maxread and a
searchwindowsize value, but I'm not sure how to use them.
Any tips? Thanks again.
On Tue, Oct 20, 2009 at 11:26 AM, vince spicer wrote:
>
>
> On Tue, Oct 20, 2009 at 11:11 AM, Nathan Farrar
> wrote:
>>
>> I haven't been able to find any real examples of pexpect usage, nor
>> documentation. Just little bits here and there, so I'm kind of
>> struggling through.
>>
>> I've got the follow bit of code I'm working with:
>>
>> def main():
>> try:
>> print 'attempting to spawn connection ... '
>> session = pexpect.spawn('ssh usern...@x.x.x.x')
>> except:
>> print 'couldn\'t spawn connection ... '
>>
>> print 'waiting for password prompt ... '
>> session.expect('password:')
>> print 'received password prompt ... '
>>
>> try:
>> print 'attempting to send password ... '
>> session.sendline(password)
>> except:
>> print 'error sending password ... '
>>
>> print 'waiting for command prompt ... '
>> session.expect(command_prompt)
>> print 'received command prompt ... '
>>
>> try:
>> print 'attempting to issue \'show version\' command ... '
>> session.sendline([expect.TIMEOUT=1, 'show version'])
>> except:
>> print 'error issuing \'show version\' command ... '
>>
>> print 'waiting for command prompt ... '
>> session.expect(command_prompt)
>> print 'received command prompt ... '
>>
>> print 'attempting to print command results ... '
>> print session.before
>>
>> print 'closing session ... '
>> session.close()
>>
>> if __name__=='__main__':
>> main()
>>
>> When I run this against a cisco device, it times out waiting for the
>> command prompt after issuing the show version command. However, if I
>> change 'show version' to something like 'blah blah' it doesn't time
>> out, and I get the results of the command (an error message that is
>> much shorter in length).
>>
>> I believe that the results of the show version command are simply too
>> large. I think I may need to increase the size of maxread &
>> searchwindowsize & set the timeout to something lower than the
>> default, but I haven't been able to figure out how to do this
>> correctly yet.
>>
>> Any help would be greatly appreciated. I'm pulling my hair out. Thank
>> you.
>>
>> --
>> "The presence of those seeking the truth is infinitely to be preferred
>> to the presence of those who think they've found it."
>>
>> –Terry Pratchett
>> ___
>> Tutor maillist - tu...@python.org
>> To unsubscribe or change subscription options:
>> http://mail.python.org/mailman/listinfo/tutor
>
> Looks like you are trying to end multiple commands to the sendline and not
> expect
> you can specify the timeout on the expect line
>
> try this code:
>
> #
>
> def main():
> try:
> print 'attempting to spawn connection ... '
> session = pexpect.spawn('ssh usern...@x.x.x.x')
> except:
> print 'couldn\'t spawn connection ... '
>
> print 'waiting for password prompt ... '
> session.expect('password:')
> print 'received password prompt ... '
>
> try:
> print 'attempting to send password ... '
> session.sendline(password)
> except:
> print 'error sending password ... '
>
> print 'waiting for command prompt ... '
> session.expect(command_prompt)
> print 'received command prompt ... '
>
> try:
> print 'attempting to issue \'show version\' command ... '
> session.sendline('show version') #: send only command
> except:
> print 'error issuing \'show version\' command ... '
>
> print 'waiting for command prompt ... '
> session.expect(command_prompt, timeout=1) #: set the timeout here
> print 'received command prompt ... '
>
> print 'attempting to print command results ... '
> print session.before
>
> print 'closing session ... '
> session.close()
>
> if __name__=='__main__':
> main()
> #==
>
> Vince
>
>
>
--
"The presence of those seeking the truth is infinitely to be preferred
to the presence of those who think they've found it."
–Terry Pratchett
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Re: [Tutor] Pexpect maxread & searchwindowsize, timeout
On Tue, Oct 20, 2009 at 11:11 AM, Nathan Farrar wrote:
> I haven't been able to find any real examples of pexpect usage, nor
> documentation. Just little bits here and there, so I'm kind of
> struggling through.
>
> I've got the follow bit of code I'm working with:
>
> def main():
>try:
>print 'attempting to spawn connection ... '
>session = pexpect.spawn('ssh usern...@x.x.x.x')
>except:
>print 'couldn\'t spawn connection ... '
>
>print 'waiting for password prompt ... '
>session.expect('password:')
>print 'received password prompt ... '
>
>try:
>print 'attempting to send password ... '
>session.sendline(password)
>except:
>print 'error sending password ... '
>
>print 'waiting for command prompt ... '
>session.expect(command_prompt)
>print 'received command prompt ... '
>
>try:
>print 'attempting to issue \'show version\' command ... '
>session.sendline([expect.TIMEOUT=1, 'show version'])
>except:
>print 'error issuing \'show version\' command ... '
>
>print 'waiting for command prompt ... '
>session.expect(command_prompt)
>print 'received command prompt ... '
>
>print 'attempting to print command results ... '
>print session.before
>
>print 'closing session ... '
>session.close()
>
> if __name__=='__main__':
>main()
>
> When I run this against a cisco device, it times out waiting for the
> command prompt after issuing the show version command. However, if I
> change 'show version' to something like 'blah blah' it doesn't time
> out, and I get the results of the command (an error message that is
> much shorter in length).
>
> I believe that the results of the show version command are simply too
> large. I think I may need to increase the size of maxread &
> searchwindowsize & set the timeout to something lower than the
> default, but I haven't been able to figure out how to do this
> correctly yet.
>
> Any help would be greatly appreciated. I'm pulling my hair out. Thank
> you.
>
> --
> "The presence of those seeking the truth is infinitely to be preferred
> to the presence of those who think they've found it."
>
> –Terry Pratchett
> ___
> Tutor maillist - Tutor@python.org
> To unsubscribe or change subscription options:
> http://mail.python.org/mailman/listinfo/tutor
>
Looks like you are trying to end multiple commands to the sendline and not
expect
you can specify the timeout on the expect line
try this code:
#
def main():
try:
print 'attempting to spawn connection ... '
session = pexpect.spawn('ssh usern...@x.x.x.x')
except:
print 'couldn\'t spawn connection ... '
print 'waiting for password prompt ... '
session.expect('password:')
print 'received password prompt ... '
try:
print 'attempting to send password ... '
session.sendline(password)
except:
print 'error sending password ... '
print 'waiting for command prompt ... '
session.expect(command_prompt)
print 'received command prompt ... '
try:
print 'attempting to issue \'show version\' command ... '
session.sendline('show version') #: send only command
except:
print 'error issuing \'show version\' command ... '
print 'waiting for command prompt ... '
session.expect(command_prompt, timeout=1) #: set the timeout here
print 'received command prompt ... '
print 'attempting to print command results ... '
print session.before
print 'closing session ... '
session.close()
if __name__=='__main__':
main()
#==
Vince
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Re: [Tutor] pexpect
James,
I've not used pexpect, but I've done this on a Cisco switch. I found
using
time.sleep and read_until of the telnet class to be helpful.
10 tn = telnetlib.Telnet('')
11 #tn.set_debuglevel(9)
12 tn.read_until('Username: \xff', 5)
13 time.sleep(10)
14 tn.write('\n')
15 tn.read_until('\r\nPassword: ', 5)
16 #time.sleep(2)
17 tn.write('\n')
18 tn.read_until('#', 5)
19 tn.write('term len 0 \n')
20 tn.read_until('#', 5)
21 tn.write('show version | i restarted\n')
22 RouterStartupTimestamp = tn.read_until('#', 2)
23 tn.read_until('#', 2)
24 tn.write('show call history voice last 100\n')
HTH,
Steve
On Sep 20, 2008, at 8:43 AM, James wrote:
Folks,
Does anyone here have experience with pexpect? I'm trying to write a
pexpect script which will log into a network device, gather
statistics, and then dump the raw output into a file (or a string so
that I can manipulate it).
I'm not having much luck. Because the connection is telnet I was able
to use wireshark (a sniffer) to see the traffic between my computer
(which is running the pexpect script) and the network device.
Everything seems to go find until I "expect" the network device's
prompt and it just hangs. Eventually pexpect throws an exception and
times out.
I'd be happy to share some code when I get to the computer I've been
testing on. :) In the time being, has anyone seen a problem like this
before?
Thanks!
-j
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