ssh remote machine and run the 'ls-l' using pexpect


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@') 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@'] 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\r\r\nroot@ubuntu14:~# ' before (last 100 chars): 'cape.canonical.com/\r\n\r\nLast login: Tue Jun 16 10:26:18 2015 from\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


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@') # 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 <em>"I waited for TIMEOUT period for a string to match your pattern, but I didn't find it."</em>

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


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\r\r\nroot@ubuntu14:~# '

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

You can <a href="http://pexpect.readthedocs.org/en/latest/overview.html#debugging" rel="nofollow">debug</a> the pexpect output.


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.


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