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I am trying to tail a log file, and it works. But I need to also be able to analyze the output and log for errors and such. I am using the base example on the Paramiko-expect github page and I can not figure out how to do this.
import traceback
import paramiko
from paramikoe import SSHClientInteraction
def main():
# Set login credentials and the server prompt
hostname = 'server'
username = 'username'
password = 'xxxxxxxx'
port = 22
# Use SSH client to login
try:
# Create a new SSH client object
client = paramiko.SSHClient()
# Set SSH key parameters to auto accept unknown hosts
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
# Connect to the host
client.connect(hostname, port, username, password)
# Create a client interaction class which will interact with the host
interact = SSHClientInteraction(client, timeout=10, display=False)
# Send the tail command
interact.send('tail -f /var/log/log')
# Now let the class tail the file for us
interact.tail(line_prefix=hostname+': ')
except KeyboardInterrupt:
print 'Ctrl+C interruption detected, stopping tail'
except Exception:
traceback.print_exc()
finally:
try:
client.close()
except:
pass
if __name__ == '__main__':
main()
This works to the point of it prints the logs live time in the console that it is run in, but I from the way paramiko expect I can't figure out how to be able to iterate over the ouput and look for values?
Help?
https://github.com/fgimian/paramiko-expect
This would also help being able to push the output of the logs to a local file for historical backups of events.
Update:
So I see that the way that this info is being displayed is using sys.stdout. I am not very seasoned on how to pull the output out of this into a interable way or how to modify this to a different type of output where it would still work. I have tried emailing the creater of this module without much success.
This module is so close to being a VERY powerful tool, if it I could figure out the ability of actually monitoring the output, it would make the module a very very good tool. Please help!
Output section of Paramiko-Expect: Tail Function:
# Read the output one byte at a time so we can detect \n correctly
buffer = self.channel.recv(1)
# If we have an empty buffer, then the SSH session has been closed
if len(buffer) == 0:
break
# Strip all ugly \r (Ctrl-M making) characters from the current
# read
buffer = buffer.replace('\r', '')
# Add the currently read buffer to the current line output
current_line += buffer
# Display the last read line in realtime when we reach a \n
# character
if current_line.endswith('\n'):
if line_counter and line_prefix:
sys.stdout.write(line_prefix)
if line_counter:
sys.stdout.write(current_line)
sys.stdout.flush()
line_counter += 1
current_line = ''
Paramiko Expect Module:
#
# Paramiko Expect
#
# Written by Fotis Gimian
# http://github.com/fgimian
#
# This library works with a Paramiko SSH channel to provide native SSH
# expect-like handling for servers. The library may be used to interact
# with commands like 'configure' or Cisco IOS devices or with interactive
# Unix scripts or commands.
#
# You must have Paramiko installed in order to use this library.
#
import sys
import re
import socket
# Windows does not have termios
try:
import termios
import tty
has_termios = True
except ImportError:
import threading
has_termios = False
import select
class SSHClientInteraction:
"""This class allows an expect-like interface to Paramiko which allows
coders to interact with applications and the shell of the connected
device.
"""
def __init__(self, client, timeout=60, newline='\r', buffer_size=1024,
display=False):
"""The constructor for our SSHClientInteraction class.
Arguments:
client -- A Paramiko SSHClient object
Keyword arguments:
timeout -- THe connection timeout in seconds
newline -- The newline character to send after each command
buffer_size -- The amount of data (in bytes) that will be read at a
time after a command is run
display -- Whether or not the output should be displayed in real-time
as it is being performed (especially useful when debugging)
"""
self.channel = client.invoke_shell()
self.newline = newline
self.buffer_size = buffer_size
self.display = display
self.timeout = timeout
self.current_output = ''
self.current_output_clean = ''
self.current_send_string = ''
self.last_match = ''
def __del__(self):
"""The destructor for our SSHClientInteraction class."""
self.close()
def close(self):
"""Attempts to close the channel for clean completion."""
try:
self.channel.close()
except:
pass
def expect(self, re_strings=''):
"""This function takes in a regular expression (or regular expressions)
that represent the last line of output from the server. The function
waits for one or more of the terms to be matched. The regexes are
matched using expression \n<regex>$ so you'll need to provide an
easygoing regex such as '.*server.*' if you wish to have a fuzzy match.
Keyword arguments:
re_strings -- Either a regex string or list of regex strings that
we should expect. If this is not specified, then
EOF is expected (i.e. the shell is completely closed
after the exit command is issued)
Returns:
- EOF: Returns -1
- Regex String: When matched, returns 0
- List of Regex Strings: Returns the index of the matched string as
an integer
"""
# Set the channel timeout
self.channel.settimeout(self.timeout)
# Create an empty output buffer
self.current_output = ''
# This function needs all regular expressions to be in the form of a
# list, so if the user provided a string, let's convert it to a 1
# item list.
if len(re_strings) != 0 and isinstance(re_strings, str):
re_strings = [re_strings]
# Loop until one of the expressions is matched or loop forever if
# nothing is expected (usually used for exit)
while (
len(re_strings) == 0 or
not [re_string
for re_string in re_strings
if re.match('.*\n' + re_string + '$',
self.current_output, re.DOTALL)]
):
# Read some of the output
buffer = self.channel.recv(self.buffer_size)
# If we have an empty buffer, then the SSH session has been closed
if len(buffer) == 0:
break
# Strip all ugly \r (Ctrl-M making) characters from the current
# read
buffer = buffer.replace('\r', '')
# Display the current buffer in realtime if requested to do so
# (good for debugging purposes)
if self.display:
sys.stdout.write(buffer)
sys.stdout.flush()
# Add the currently read buffer to the output
self.current_output += buffer
# Grab the first pattern that was matched
if len(re_strings) != 0:
found_pattern = [(re_index, re_string)
for re_index, re_string in enumerate(re_strings)
if re.match('.*\n' + re_string + '$',
self.current_output, re.DOTALL)]
self.current_output_clean = self.current_output
# Clean the output up by removing the sent command
if len(self.current_send_string) != 0:
self.current_output_clean = (
self.current_output_clean.replace(
self.current_send_string + '\n', ''))
# Reset the current send string to ensure that multiple expect calls
# don't result in bad output cleaning
self.current_send_string = ''
# Clean the output up by removing the expect output from the end if
# requested and save the details of the matched pattern
if len(re_strings) != 0:
self.current_output_clean = (
re.sub(found_pattern[0][1] + '$', '',
self.current_output_clean))
self.last_match = found_pattern[0][1]
return found_pattern[0][0]
else:
# We would socket timeout before getting here, but for good
# measure, let's send back a -1
return -1
def send(self, send_string):
"""Saves and sends the send string provided"""
self.current_send_string = send_string
self.channel.send(send_string + self.newline)
def tail(self, line_prefix=None):
"""This function takes control of an SSH channel and displays line
by line of output as \n is recieved. This function is specifically
made for tail-like commands.
Keyword arguments:
line_prefix -- Text to append to the left of each line of output.
This is especially useful if you are using my
MultiSSH class to run tail commands over multiple
servers.
"""
# Set the channel timeout to the maximum integer the server allows,
# setting this to None breaks the KeyboardInterrupt exception and
# won't allow us to Ctrl+C out of teh script
self.channel.settimeout(sys.maxint)
# Create an empty line buffer and a line counter
current_line = ''
line_counter = 0
# Loop forever, Ctrl+C (KeyboardInterrupt) is used to break the tail
while True:
# Read the output one byte at a time so we can detect \n correctly
buffer = self.channel.recv(1)
# If we have an empty buffer, then the SSH session has been closed
if len(buffer) == 0:
break
# Strip all ugly \r (Ctrl-M making) characters from the current
# read
buffer = buffer.replace('\r', '')
# Add the currently read buffer to the current line output
current_line += buffer
# Display the last read line in realtime when we reach a \n
# character
if current_line.endswith('\n'):
if line_counter and line_prefix:
sys.stdout.write(line_prefix)
if line_counter:
sys.stdout.write(current_line)
sys.stdout.flush()
line_counter += 1
current_line = ''
def take_control(self):
"""This function is a better documented and touched up version of the
posix_shell function found in the interactive.py demo script that
ships with Paramiko"""
if has_termios:
# Get attributes of the shell you were in before going to the
# new one
original_tty = termios.tcgetattr(sys.stdin)
try:
tty.setraw(sys.stdin.fileno())
tty.setcbreak(sys.stdin.fileno())
# We must set the timeout to 0 so that we can bypass times when
# there is no available text to receive
self.channel.settimeout(0)
# Loop forever until the user exits (i.e. read buffer is empty)
while True:
select_read, select_write, select_exception = (
select.select([self.channel, sys.stdin], [], []))
# Read any output from the terminal and print it to the
# screen. With timeout set to 0, we just can ignore times
# when there's nothing to receive.
if self.channel in select_read:
try:
buffer = self.channel.recv(self.buffer_size)
if len(buffer) == 0:
break
sys.stdout.write(buffer)
sys.stdout.flush()
except socket.timeout:
pass
# Send any keyboard input to the terminal one byte at a
# time
if sys.stdin in select_read:
buffer = sys.stdin.read(1)
if len(buffer) == 0:
break
self.channel.send(buffer)
finally:
# Restore the attributes of the shell you were in
termios.tcsetattr(sys.stdin, termios.TCSADRAIN, original_tty)
else:
def writeall(sock):
while True:
buffer = sock.recv(self.buffer_size)
if len(buffer) == 0:
break
sys.stdout.write(buffer)
sys.stdout.flush()
writer = threading.Thread(target=writeall, args=(self.channel,))
writer.start()
try:
while True:
buffer = sys.stdin.read(1)
if len(buffer) == 0:
break
self.channel.send(buffer)
# User has hit Ctrl+Z or F6
except EOFError:
pass
233
I'm the author of paramiko-expect.
I've implemented a new feature in 0.2 of my module just now which will allow you to specify a callback to the tail method so that you can process the current line as you like. You may use this to grep the output or process it further before displaying it. It is expected that the callback function will return the string that is to be sent to sys.stdout.write after it has finished manipulating the current line.
Here's an example:
import traceback
import paramiko
from paramikoe import SSHClientInteraction
def process_tail(line_prefix, current_line):
if current_line.startswith('hello'):
return current_line
else:
return ''
def main():
# Set login credentials and the server prompt
hostname = 'localhost'
username = 'fots'
password = 'password123'
port = 22
# Use SSH client to login
try:
# Create a new SSH client object
client = paramiko.SSHClient()
# Set SSH key parameters to auto accept unknown hosts
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
# Connect to the host
client.connect(hostname, port, username, password)
# Create a client interaction class which will interact with the host
interact = SSHClientInteraction(client, timeout=10, display=False)
# Send the tail command
interact.send('tail -f /home/fots/something.log')
# Now let the class tail the file for us
interact.tail(line_prefix=hostname+': ', callback=process_tail)
except KeyboardInterrupt:
print 'Ctrl+C interruption detected, stopping tail'
except Exception:
traceback.print_exc()
finally:
try:
client.close()
except:
pass
if __name__ == '__main__':
main()
So this question has been up for almost 24 hours on 3 different websites and not one true answer was givin related to this. I am kind of shocked. I tried running the script as a subprocess and then piping the output to stdout. It worked:
import subprocess
proc = subprocess.Popen(['python','tail_try.py'],stdout=subprocess.PIPE)
for line in iter(proc.stdout.readline, ''):
print line
I can now control the output for every line printed proc.stdout.readline.
Such a simple answer really.
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