if then logic inside expect script

Question

I have an expect script I use for ssh. Some of my hosts prompt with the RSA host key text and some do not. How can I setup my script for an if/then in expect. Here is what I have so far.

#!/usr/bin/expect -f

set ipaddress [lindex $argv 0];
spawn ssh user@$ipaddress
expect "Are you sure you want to continue connecting (yes/no)?"
send "yes\r"
expect "user@$ipaddress's password:"
send "password\r"
set prompt {\$ $}
expect -re $prompt
send "$command\r"
expect -re $prompt
send "quit\r"
interact

The part I need to build in the if/then logic are these two lines:

expect "Are you sure you want to continue connecting (yes/no)?"
send "yes\r"

The logic flow would be:

if expect "Are you sure you want to continue connecting (yes/no)?"
then send "yes\r"
else
expect "user@$ipaddress's password:"
etc..

How can I accomplish this?

Answer 1

This is working for me with the following code modifications.

expect {
    "Are you sure you want to continue connecting (yes/no)?" {
         send "yes\r"
         exp_continue
    }
    "user@$ipaddress's password:" {
         send "password\r"
    }
    }