Hi all,

I hope someone can help me out here. I have a TCL expect script that spawns a telnet session to a Nortel DMS100 to execute some commands. The strange thing is that the response in expect_out is not consistent. It sometimes contains a extra enter or newline. This results in differences in the expect out buffer. Here is a part of the script:

send "time\r"
sleep 1
expect -re ">"
set output $expect_out(buffer)
set output [split $output "\r\n"]
puts $output


This command displays the time. The correct output should be (with log_user=1):

>time
Time is 11:44:04
>

But sometimes the output is:

>timeTime is 11:45:04
>

As you can see here the \r is missing on the command that expect sends , or at least in the echo that is comming back.

I use a split command to filter out the response in the expect_out buffer, but this fails when the \r is missing. Here is a example with the debug enabled:

Wrong:
----------------------------------------------------------
send: sending "time\r" to { exp4 }

expect: does "" (spawn_id exp4) match regular expression ">"? no
timeTime is 11:47:11
>
expect: does "timeTime is 11:47:11\r\r\n>" (spawn_id exp4) match regular expression ">"? yes
expect: set expect_out(0,string) ">"
expect: set expect_out(spawn_id) "exp4"
expect: set expect_out(buffer) "timeTime is 11:47:11\r\r\n>"
{timeTime is 11:47:11} {} {} >
-----------------------------------------------------------

Good:
------------------------------------------------------------
send: sending "time\r" to { exp4 }

expect: does "" (spawn_id exp4) match regular expression ">"? no
time
Time is 11:47:59
>
expect: does "time\r\nTime is 11:47:59\r\r\n>" (spawn_id exp4) match regular expression ">"? yes
expect: set expect_out(0,string) ">"
expect: set expect_out(spawn_id) "exp4"
expect: set expect_out(buffer) "time\r\nTime is 11:47:59\r\r\n>"
time {} {Time is 11:47:59} {} {} >
--------------------------------------------------------------

I suspect it has something to do with a slow response of the switch. I tried to send the time command slow and with the send_human but the result is the same. A timeout between the send and expect also doesen't help.

Does anyone here have a clue how to further debug/fix this issue?

Thanks,

Jenus

Just made a tcpdump from the telnet session and it seems the DMS sometimes doesen't send the \r , wich results in the command and output on the same line.

can it be this has something to do with the telnet line/character mode? The DMS uses a IBM AIX unix machine, thats where i'm telnetting to. I tried to replicate the same issue on a cisco device but here i don't have the issue. So it seems that it has something to do with the AIX unix telnet implementation.