How to use Expect inside a Bash script - bash

Question

This is the code snippet I am using in the following Bash script:
for user_input in `awk '{print}' testfile_$$.txt`
do
ipaddress=`echo $user_input | cut -d';' -f 1`
command="${config_mode}`echo $user_input | cut -d';' -f 2-`"
ping -w 1 $ipaddress 1> /dev/null 2> $ERR_LOG_FILE 1> $LOG_FILE
if [ $? -eq 0 ];then
ssh "$USERNAME#$ipaddress" "$command"
>> $LOG_FILE
fi
done
How do I use Expect to automate the SSH login in this script?
I am very new to Expect and started testing this (it failed):
#!/usr/bin/bash
set force_conservative 0 ;# Set to 1 to force conservative mode even if
;# script wasn't run conservatively originally
if {$force_conservative} {
set send_slow {1 .1}
proc send {ignore arg} {
sleep .1
exp_send -s -- $arg
}
}
#
set timeout -1
spawn ssh auto21#10.38.227.229 {uname -a; df -h}
match_max 100000
expect "*?assword: "
send -- "bar01\r"
expect eof
Do I need to write the Bash script all over again in an Expect script or can Expect be used inside a Bash script?
If it can be done:
Moreover, I need to get the Bash variables $command, $username, $password, and $ipaddress and use it in the Expect part.
What solution would you suggest?
Or can I create an Expect script and call it from the Bash script just for login, error handling, execution, and logfiles.

Answer 1

Well, you will need to run two separate scripts, a shell script that calls an Expect script:
#!/usr/bin/bash
set force_conservative 0 ;
Change the above to
#!/usr/bin/expect
set force_conservative 0 ;
Or alternatively in your shell script I am unsure about the format, but you can send expect -c with the command to execute:
expect -c "send \"hello\n\"" -c "expect \"#\""
expect -c "send \"hello\n\"; expect \"#\""
Actually, there is also one other alternative:
#!/bin/bash
echo "shell script"
/usr/bin/expect<<EOF
set force_conservative 0 ;# Set to 1 to force conservative mode even if
;# script wasn't run conservatively originally
if {$force_conservative} {
set send_slow {1 .1}
proc send {ignore arg} {
sleep .1
exp_send -s -- $arg
}
}
#
set timeout -1
spawn ssh auto21#10.38.227.229 {uname -a; df -h}
match_max 100000
expect "*?assword: "
send -- "bar01\r"
expect eof
EOF