Trouble using telentlib

[Nitin Chaumal]

I sarched the existing threads but didnt find an answer to this.

I am writing simple script which uses telentlib to open a session with
a unix machine and run "tail -f logfile.txt" on one of the logfiles.

import telnetlib

HOST = "192.X.X.X"
user = "myname"
password = "mypass"

tn = telnetlib.Telnet(HOST)

tn.read_until("login: ")
tn.write(user + "\n")
if password:
tn.read_until("Password: ")
tn.write(password + "\n")

tn.write("tail -f /tmp/logfile.txt\n")

# what do i write here ? #

tn.write("exit\n")

I want to read every line of the output into a string and run regex on
it.
I tried tn.interact() which does show me the ouput but the CPU usage
on my win2k machine reaches 99% !! :(

How do i execute a command and then read its output, then another
command and read its output and so on. I tried to find docs on
telnetlib but in vain.

Can somebody guide me please

Thanks
Nitin

[Kartic]

Nitin Chaumal said the following on 2/11/2005 5:41 PM:

I sarched the existing threads but didnt find an answer to this.

I am writing simple script which uses telentlib to open a session with
a unix machine and run "tail -f logfile.txt" on one of the logfiles.

import telnetlib

HOST = "192.X.X.X"
user = "myname"
password = "mypass"

tn = telnetlib.Telnet(HOST)

tn.read_until("login: ")
tn.write(user + "\n")
if password:
tn.read_until("Password: ")
tn.write(password + "\n")

tn.write("tail -f /tmp/logfile.txt\n")

# what do i write here ? #

tn.write("exit\n")

Nitin,

You can not have two writes together. Reads and writes should alternate.

To get the log file this is what you should do:

# Modified my working version for your purpose.
# Hope there are not errors!

def SaveLog(user, password):
telnet_resp = []
tn = telnetlib.Telnet(host)

tn.read_until("login: ")
tn.write(user + "\n")
if password:
telnet_resp.append( tn.read_until("Password: ") )
tn.write(password + "\n")
tn.read_until("$ ")
tn.write("tail -f /tmp/logfile.txt\n")
telnet_resp.append(tn.read_until("$ "))
tn.write("exit\n")

telnet_resp.append(tn.read_all() )
tn.close()
telnet_out = open(OUTPUT, 'a')
telnet_out.write('\n'.join(telnet_resp))
telnet_out.close()
Alternatively, if your box has FTP access, you can FTP the log file to a
CStringIO file and operate on it.

Thanks,
-Kartic

[Eddie Corns]

ni******@yahoo.com (Nitin Chaumal) writes:

I sarched the existing threads but didnt find an answer to this. I am writing simple script which uses telentlib to open a session with
a unix machine and run "tail -f logfile.txt" on one of the logfiles. import telnetlib HOST = "192.X.X.X"
user = "myname"
password = "mypass" tn = telnetlib.Telnet(HOST) tn.read_until("login: ")
tn.write(user + "\n")
if password:
tn.read_until("Password: ")
tn.write(password + "\n") tn.write("tail -f /tmp/logfile.txt\n") # what do i write here ? # tn.write("exit\n") I want to read every line of the output into a string and run regex on
it.
I tried tn.interact() which does show me the ouput but the CPU usage
on my win2k machine reaches 99% !! :( How do i execute a command and then read its output, then another
command and read its output and so on. I tried to find docs on
telnetlib but in vain. Can somebody guide me please Thanks
Nitin

tn.write("tail -f /tmp/logfile.txt\n")
while True:
# get one more line
line = tn.read_until ('\n')
regex_thing (line)

Remember, "tail -f" never exits, so you probably want to break when you've
find what you want and then just close the telnet session. It would probably
be nice if telnetlib had a readline function that handled all the messy
details for portable end of line checking.

Eddie