bash/expect/loop - how to loop a simple bash script doing telnet

Question

I would like to run this script in a loop.

What is needs to do is read a file with in that file IP addresses like:

10.0.0.0
10.0.0.1
10.0.0.2
10.0.0.3
10.0.0.4

And run this script on every ip listed above here.

This is what i have:

#!/usr/bin/expect

spawn telnet 10.0.0.0
expect "User Name :"
send "username\r"

expect "Password  :"
send "password\r"
expect ">"
send "4\r"
expect "*#"
exit

How do i get the script above working every IP in a txt file.

Answer 1

You can read the file within your expect script.

Open the file and assign the file descriptor to a variable, read each line and execute the above code you wrote.

set fildes [open "myhosts.txt" r]
set ip [gets $fildes]
while {[string length $ip] > 0} {

    spawn telnet $ip
    expect "User Name :"
    send "username\r"

    expect "Password  :"
    send "password\r"
    expect ">"
    send "4\r"
    expect "*#"
    exit
    set ip [gets $fildes]
}
close $fildes

Answer 2

I'm not an expert with expect, but the first thing you need to do is change your expect script to accept arguments. It should work like this (looks like you'll need -f in #!/usr/bin/expect):

#!/usr/bin/expect -f

set ip [lindex $argv 0]
spawn telnet $ip
...

Then you can simply iterate over the list of your IPs in your bash script:

while read ip ; do
    myExpectScript $ip
done < list_of_ip.txt

Answer 3

This is just a comment on @user3088572's answer. The idiomatic way to read a file line by line is:

set fildes [open "myhosts.txt" r]
while {[gets $fildes ip] != -1} {
    # do something with $ip
}
close $fildes