Using bash commands in expect script

Question

I've tried using some bash commands in an expect script before spawning anything, and this doesn't seem to work:

#!/usr/bin/expect

sudo ifdown usb0
sudo ifup usb0

expect "[sudo] password for stud:"
send "FirstPassword\r"

spawn ssh root@10.9.8.2
expect "root@10.9.8.2's password:"
send "SecondPassword\r"

expect eof

I've tried running this with the first part of the script commented out (because it's not neccesary to do this check 100% of the time, just better), but in that case I enter the device, and literally can't do anything there. I'd like to ifdown ifup, enter pass, ssh, enter pass, and scope to that shell.

Answer 1

Nope. you can't expect to run bash commands in an expect interpreter, just like you can't run perl commands in a python interpreter -- they're different languages. If you want to run some bash commands that require user interaction (sudo), then you have to spawn bash

set prompt {\$ $}    ; # this is a regular expression that should match the
                       # *end* of you bash prompt. Alter it as required.
spawn bash
expect -re $prompt

send "sudo ifdown usb0\r"
expect {
    "[sudo] password for stud:" {
        send "FirstPassword\r"
        exp_continue
    }
    -re $prompt
}
send "sudo ifup usb0\r"
expect -re $prompt

send "ssh root@10.9.8.2\r"
expect "root@10.9.8.2's password:"
send "SecondPassword\r"
expect eof