Question

The target of the following simple expect script is to get the hostname name on the remote machine

Sometimes expect script fail to perform ssh to $IP_ADDRESS ( because remote machine not active , etc )

so in this case the expect script will break after 10 second (timeout 10) , this is OK but……

There are two options

1. Expect script perform ssh successfully , and performed the command hostname on the remote machine
2. Expect script break because timeout was 10 seconds

On both cases expect will exit

• in case of ssh successfully expect will break after 0.5-1 second but in case of bad ssh then it will break after 10 seconds

but I don’t know if expect script perform ssh successfully or not?

is it possible to identify timeout process ? or to verify that expect ended because timeout?

Remark my Linux machine version – red-hat 5.1

Expect script

 [TestLinux]# get_host_name_on_remote_machine=`cat << EOF
  > set timeout 10
  > spawn  ssh   $IP_ADDRESS
  >            expect {
  >                      ")?"   { send "yes\r"  ; exp_continue  }
  > 
  >                      word:  {send $PASS\r}
  >                   }
  > expect >  {send "hostname\r"}
  > expect >    {send exit\r}
  > expect eof
  > EOF`

Example in case we not have connection to the remote host

 [TestLinux]# expect -c  "$get_host_name_on_remote_machine"
 spawn ssh 10.17.180.23
 [TestLinux]# echo $?
 0

Answer 1

To do sensible things on timeout, you need to tell expect what should happen:

set timeout 10
expect {
    ")?"     { send "yes\r"  ; exp_continue  }
    "word:"  { send "$PASS\r"                }
    timeout  { puts "timed out during login"; exit 1 }
}
set timeout -1   ; # Infinite...
expect ">"   { send "hostname\r"             }
expect ">"   { send "exit\r"                 }
expect eof
exit

Notice above how I use exit 1 when I hit an error. Your shell will be able to pick that up through $?, etc. (Without the 1 argument, the exit command will cause the script to terminate “successfully”; the same happens if you drop off the bottom of the script.)