Is it possible to set exit code of 'expect' - linux

Question

The following bash script doesn't work because command 'expect' always return 0 regardless which exit code of the remote script /tmp/my.sh returns.
any idea to make it work? thanks.
#!/usr/bash
user=root
passwd=123456abcd
host=10.58.33.21
expect -c "
spawn ssh -o StrictHostKeyChecking=no -l $user $host bash -x /tmp/my.sh
expect {
\"assword:\" {send \"$passwd\r\"}
eof {exit $?}
}
"
case "$?" in
0) echo "Password successfully changed on $host by $user" ;;
1) echo "Failure, password unchanged" ;;
2) echo "Failure, new and old passwords are too similar" ;;
3) echo "Failure, password must be longer" ;;
*) echo "Password failed to change on $host" ;;
esac
Edited at 10:23 AM 11/27/2013
Thanks for the comments. Let me emphasis the problem once again,
The main script is supposed to run on linux server A silently, during which it invokes another script my.sh on server B unattended. The question is how to get exit code of my.sh?
That's why I cannot leverage ssl_key approach in my case, which requires at least one time configuration.

Answer 1

#!/usr/bin/expect
set user root
set passwd 123456abcd
set host 10.58.33.21
set result_code 255
# exp_internal 1 to see internal processing
exp_internal 0
spawn ssh -o StrictHostKeyChecking=no -l $user $host bash -x /tmp/my.sh && echo aaa0bbb || echo aaa$?bbb
expect {
"assword:" {send "$passwd\r"; exp_continue}
-re "aaa(.*)bbb" {set result_code $expect_out(1,string)}
eof {}
timeout {set result_code -1}
}
switch $result_code {
0 { puts "Password successfully changed on $host by $user" }
1 { puts "Failure, password unchanged" }
2 { puts "Failure, new and old passwords are too similar" }
3 { puts "Failure, password must be longer" }
-1 { puts "Failure, timeout" }
default { puts "Password failed to change on $host" }
}
exit $result_code