Python telnetlib not reading everything

I'm trying to automate the download of Argos data using Python's telnetlib, but I can't seem to figure out how to get it to download all of the output. Part of my problem may be that I don't really understand the seemingly asynchronous nature of the commands.

Here's the code:

tn = telnetlib.Telnet(host = HOST, timeout = 60)
with open("argos_prv_{0}-1.txt".format(now_str), 'w') as of:
    tn.read_until("Username: ")
    tn.write(user + "\n")
    tn.read_until("Password: ")
    tn.write(password + "\n")
    tn.read_until("/")
    # Here's the command I'm trying to get the results of:
    tn.write("prv,,ds,{0:d},009919,009920\n".format(start_doy))
   开发者_如何学编程 # At this point, it's presumably dumped it all
    tn.read_until("ARGOS READY")
    tn.read_until("/")
    # Logging out
    tn.write("lo\n")
    lines = tn.read_all()
    of.write(lines)
    of.flush()

The code seems to run just fine, but when I look at the output file, it never has everything in it, cutting out at some random point. When I type the same commands in a real telnet session, it works just fine.

I get the sense it has something to do with trying to read_all() after logging out (tn.write("lo\n")), but when I look at the example documentation for telnetlib, it pretty much looks just like this.

Anyway, my question is: can anyone see what I'm doing wrong here? I want to grab the results of the prv,,ds command, but I'm only getting some of it using this particular code.

Thanks.

# At this point, it's presumably dumped it all
tn.read_until("ARGOS READY")
tn.read_until("/")

At a guess, this bit is sucking up the data and doing nothing with it. Think of it like a pair of pipes - you send stuff one way with write, and pull stuff back with read_*. If you've already sucked the stuff up, it won't still be waiting in the pipe when you do read_all later.

EDIT: OK, you're seeing a different problem. Try this:

lines = tn.read_until("ARGOS READY")
lines += tn.read_until("/")
tn.write("lo\n")
# Write out lines to file.