'expect' not matching server response string

Question

I'm using a bash script to log into a telnet server and execute a number of commands. It looks like:

login_and_run.sh

#!/bin/bash

unset TELNET_USER_NAME_STRING
unset TELNET_PASSWORD_STRING
unset TELNET_USER_NAME
unset TELNET_PASSWORD

TELNET_USER_NAME_STRING=`cat SAP_output`
TELNET_PASSWORD_STRING="Password:"

TELNET_USER_NAME="UserNam3\r"
TELNET_PASSWORD="Passw0rd\r"

# Expect script starts here
expect <<- DONE
        spawn telnet localhost 50008
        expect '$TELNET_USER_NAME_STRING'
        send "$TELNET_USER_NAME"
        sleep 3
        expect "$TELNET_PASSWORD_STRING"
        send "$TELNET_PASSWORD"
        sleep 3
        spawn ls
        expect eof
DONE

where

SAP_output:

Trying ::1...
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.

   ***********************************************
   **********************************************
   ****###*******####*****#######**************
   **##***##****##**##****##****##************
   ***##*******##****##***##****##**********
   *****##*****########***######***********
   ******##****##****##***##*************
   **##***##**##******##**##************
   ****###****##******##**##**********
   **********************************
   ********************************

   Telnet Administration
   SAP Java EE Application Server v7.50


User name:

telnet logs in, I get the banner, but it stops there (as if the strings are not matching). Would it be safer to use wildcards instead of the exact response (and match only " User name: ")?

Note that single quotes have no special meaning in expect/tcl. You are expecting to see literal single quotes. — glenn jackman, Aug 16 '19 at 13:47
Also, expect uses `\r\n` for newlines, and that file, I'm guessing, does not contain carriage returns. — glenn jackman, Aug 16 '19 at 13:49
When composing an expect program, turn on verbose debugging with `exp_internal 1` -- that will show you when your patterns are not matching. — glenn jackman, Aug 16 '19 at 13:49

Sebi · Answer 1 · 2019-08-15T16:40:20.523

Figured it out:

TELNET_USER_NAME_STRING='*name:*'

TELNET_PASSWORD_STRING='*assword:*'

TELNET_USER_NAME='UserNam3\r'
TELNET_PASSWORD='Passw0rd\r'

# Expect script starts here
expect <<- DONE
        spawn telnet localhost 50008
        expect '$TELNET_USER_NAME_STRING'
        send "$TELNET_USER_NAME"
        expect '$TELNET_PASSWORD_STRING'
        send "$TELNET_PASSWORD"
        # Check if we're logged in
        expect eof
DONE

Use wildcards instead of the full banner and return line character '\r' to 'press' enter.

Edit:

This is a far more elegant answer.

'expect' not matching server response string

1 Answers1