Python Telnetlib read_until 'a' and 'b' and 'c' and 'd'

Question

When I connect to the telnet session using the telnetlib module, i need to wait for four strings: 'a', 'b', 'c' and 'd' or timeout (10 seconds) before I write a string to the socket.

Is there a way to use tn.read_until('a','b','c','d', timeout)

I just want to wait for all 4 strings to come first before action.

Also these four strings comes in a different order every time. Thanks for any help.

Answer 1

You can use the .expect method to wait for a, b, c or d

Telnet.expect(list[, timeout])

Read until one from a list of a regular expressions matches.

So:

(index, match, content_including_abcd) = tn.expect(['a', 'b', 'c', 'd'], timeout)

Returns (-1, None, current_buffer) when timeout is reached.

---

We could easily change it to a loop to wait for a, b, c and d:

deadline = time.time() + timeout
remaining_strings = ['a', 'b', 'c', 'd']
total_content = ''
while remaining_strings:
    actual_timeout = deadline - time.time()
    if actual_timeout < 0:
        break
    (index, match, content) = tn.expect(remaining_strings, actual_timeout)
    total_content += content
    if index < 0:
        break
    del remaining_strings[index]