Shell Programming and Scripting

yes it is;

Here is a script I use to logon into dell racs to chekc configurations... Id rather just post an example for you because I spent a good 7-8 hours trying to figure out how to do this type of stuff with expect.. so hopefully this will save you some time.

Code:

#!/usr/bin/expect -f

set ipaddress [lindex $argv 0]
set passwd1 [lindex $argv 1]
set passwd2 [lindex $argv 2]

set timeout 10
spawn ssh -o StrictHostKeyChecking=no root@$ipaddress {my commands here}
expect {
  "Warning: *" {
    exp_continue
  }
  "root@${ipaddress}*" {
    send "${passwd1}\r"
    exp_continue
  }
  "Permission denied*" {
    expect "root@${ipaddress}*"
    send "${passwd2}\r"
    exp_continue
  }
  "return comment of my command" {
    return 0
  }
  timeout {
    return 1
  }
  "*" {
    return 2
  }
}
expect eof

as you can see I run the ssh command... it will cycle through 2 possible passwords and then look for return phrase my command gives... I dont think the timeout portion works.. but I wrap the script in a bash script and verify I can connect to the ip before running this script.

simply put there is not much out on google for advanced expect scripts but hopefully this will get you going. There is also an expect automate tool to help you get the intial formatting down.. forget how to run it though.

This reminds me a lot of the late 80's and early 90's when we used ppp to dial a modem to connect to our ISP or a bulletin board and a chat script to wait for the username and password prompts and send them so we didn't have to do it manually.

Fast forward a couple decades. Now we have always-connected high-speed internet (do you?) and use SSH and keychain.

It sounds like you can already make an SSH connection, so I assume SSH is setup and keys generated.

Now copy the ~/.ssh/id_dsa.pub from the local machine to the ~/.ssh/authorized_keys on the remote machine. The .pub file is one very long line of text. If the authorized_keys file already exists, append the id_dsa.pub file to the end of it, or create a new file if it does not exist. Set the mode bits of authorized_keys to 0600 with chmod (important).

Now you should be able to do password-less logins to the remote computer, although you will be prompted to enter the passphrase to unlock your local ssh key (assuming you entered a passphrase when your created it). If you can't, you may need to change the local ssh configuration.

To avoid entering your passphrase each time, install keychain. It will remember your passphrase (in memory, not on disk) and make the connection automatically.

I routinely do things like this:

Code:

ssh mywebserver.com 'ls -tor public_html/img/ | grep png'
scp somefile.txt otherpc:text/
ssh myserver.com cat public_html/intro/index.html | grep something

Note that the first grep command ran on the remote server, while the third command copied the whole file to my PC and my local copy of grep parsed it.

The possibilities are endless. And no expect or chat scripts are required.

You're assuming the remote host is a computer that has such things as accounts or, for that matter, files. I suggest reading page 1 of the topic...

I don't understand the attitude. Or why your are suggesting anything to me.

In post 4 of this thread the OP expressed concern about how to use expect but not about ssh. And the target was identified as a linux box.

I did however make assumptions about what the OP wants. Questions posted on forums like this rarely have enough information. If we want to be helpful, we have to assume a likely scenario and answer it. If we guess wrong, it tends to draw out more detail.

I appreciate all the comments, especially that of trey85-- those kinds of comments are the most useful.

Specifically, what I'm trying to figure out is how to change the passwords of an assortment of switches on my private network... so using ssh keys seems impossible (unless I'm mistaken).

My plan was to use an expect script that automated ssh as a template to do so.

One problem I'm running into is sending a command to the machine I ssh into-- I do something like:

Code:

spawn ssh -o StrictHostKeyChecking=no <some address>
expect "Password:"
send <some password>
expect "%" # I think this is the proper notation for expecting a blank prompt
send ls

using ls as an example command. And for whatever reason, this script does not operate as intended.

Specifically, using the verbose output stream of expect-- I am given a:

Code:

send: sending "ls" to { exp6 }

and then the script times out. Any ideas?

---------- Post updated at 09:57 AM ---------- Previous update was at 09:56 AM ----------

By the way, I am aware that you can send commands through ssh.

But in the case of using switch commands after a successful ssh-- that implementation would not be useful.