ssh remote machine and run the 'ls-l' usin

Question

I wanted to ssh remote machine and run the ls-l using pexpect. i am a system engineer learning the python language and don't have knowledge on coding. Could someone please assist me in this. Thanks in advance.

My code:

import pexpect
child = pexpect.spawn('/usr/bin/ssh root@192.168.32.1')
child.expect('password:', timeout=120)
child.sendline('pass123')
child.expect ('prompt# ')
#child.maxread=100000
child.sendline ('uname -a')
child.expect ('prompt# ')
print child.before, child.after

Below is the error output when run the above code.

usr/bin/python /root/PycharmProjects/IS_LAB/pexpect-test.py
Traceback (most recent call last):
  File "/root/PycharmProjects/IS_LAB/pexpect-test.py", line 36, in <module>
    child.expect ('prompt# ')
  File "/usr/lib/python2.6/site-packages/pexpect/__init__.py", line 1451, in expect
    timeout, searchwindowsize)
  File "/usr/lib/python2.6/site-packages/pexpect/__init__.py", line 1466, in expect_list
    timeout, searchwindowsize)
  File "/usr/lib/python2.6/site-packages/pexpect/__init__.py", line 1568, in expect_loop
    raise TIMEOUT(str(err) + '\n' + str(self))
pexpect.TIMEOUT: Timeout exceeded.
<pexpect.spawn object at 0x9b4110>
version: 3.3
command: /usr/bin/ssh
args: ['/usr/bin/ssh', 'root@192.168.32.1']
searcher: <pexpect.searcher_re object at 0x9b4450>
buffer (last 100 chars): 'cape.canonical.com/\r\n\r\nLast login: Tue Jun 16 10:26:18 2015 from 192.168.32.1\r\r\nroot@ubuntu14:~# '
before (last 100 chars): 'cape.canonical.com/\r\n\r\nLast login: Tue Jun 16 10:26:18 2015 from 192.168.32.1\r\r\nroot@ubuntu14:~# '
after: <class 'pexpect.TIMEOUT'>
match: None
match_index: None
exitstatus: None
flag_eof: False
pid: 13015
child_fd: 3
closed: False
timeout: 30
delimiter: <class 'pexpect.EOF'>
logfile: None
logfile_read: None
logfile_send: None
maxread: 2000
ignorecase: False
searchwindowsize: None
delaybeforesend: 0.05
delayafterclose: 0.1
delayafterterminate: 0.1

Process finished with exit code 1

Answer 1

The Problem is when you login to any linux box for first time it prompts you for RSA exception. We need to add the Keys permanently in device to avoid this. Hence login from Your Source device to destination device and add the ssh RSA to Linux box.

Answer 2

pexpect has not found the string you are expecting (prompt#), so it raised an error.

In the stacktrace in can see buffer value:

'cape.canonical.com/\r\n\r\nLast login: Tue Jun 16 10:26:18 2015 from 192.168.32.1\r\r\nroot@ubuntu14:~# '

You should expect root@ubuntu14:~# or # instead of prompt#.

You can debug the pexpect output.

Answer 3

Here is what is going on with your code, it may help you understand why your script is not working:

import pexpect

child = pexpect.spawn('/usr/bin/ssh root@192.168.32.1')

# This line means, "wait until you see a string that matches password:"
# in the response
child.expect('password:', timeout=120) 

child.sendline('pass123') # Send the characters pass123 and "enter"

# Wait till you see a string matching prompt#
child.expect ('prompt# ')

At this line, your script is searching for the string prompt#, but what the server is returning is root@ubuntu14:~#. As this doesn't match what you have provided for the script to check for, it raises an exception, which basically means "I waited for TIMEOUT period for a string to match your pattern, but I didn't find it."

To solve the problem you can either enter the exact prompt string for your script to search for, like this:

child.sendline('pass123') # Send the characters pass123 and "enter"

# Wait till you see a string matching ~#
child.expect('~#')
child.sendline ('uname -a')

child.expect ('~#')
print child.before, child.after

Or simply pause your script for a few seconds:

import time

child.sendline('pass123') # Send the characters pass123 and "enter"
time.sleep(10)

child.sendline('uname -a')
time.sleep(10)

print child.before, child.after