Replying to prompts in an automated script

mpettis has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

I am writing a perl script to automate the spinning up of new instances in Amazon's EC2 cloud computing environment. The script will launch a new instance, do some admin on it via putty or ssh, and update some other config information (such as letting a proxy know that it can balance to the new server).

The problem is that when spinning up a new instance, the first interaction with putty or ssh requires you to confirm the fingerprints of the new server. I want to either skip this or tell the process prompt 'yes' to confirm and move on. Can I respond to this prompt in a perl script with a canned response, and if so, how?

Thanks, Matt

Comment on Replying to prompts in an automated script

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Re: Replying to prompts in an automated script by Corion (Patriarch) on Nov 23, 2008 at 20:52 UTC
You want to set up passwordless keys for `ssh`. Automating entering the password is tedious, you will have to use Expect for that, or possibly use a Perl ssh client, like one of those that can be found through SSH. I recommend simply using passwordless keys. Ooops - I just realized that you want/need to accept the hosts fingerprints. I don't know any way other than Expect for that, except finding the fingerprint via other means, and storing it in the `.ssh/known_hosts` file yourself.	[reply] [d/l] [select]
Re: Replying to prompts in an automated script by oeuftete (Monk) on Nov 23, 2008 at 21:57 UTC
This doesn't answer your question directly, but you can set an option with the OpenSSH client to skip that confirmation: `$ ssh -o StrictHostKeyChecking=false remote_host` [download] I don't see immediately see an option in putty to do anything similar.	[reply] [d/l]
Re^2: Replying to prompts in an automated script by mpettis (Beadle) on Nov 25, 2008 at 00:42 UTC
This was perfect! Thanks!	[reply]
Re: Replying to prompts in an automated script by moritz (Cardinal) on Nov 23, 2008 at 22:01 UTC
Maybe Net::Amazon::EC2 automates some of that for you?	[reply]
Re: Replying to prompts in an automated script by imrags (Monk) on Dec 10, 2008 at 11:32 UTC
I have a similar problem.... I've a windows machine, I have to telnet to about 180 machines...and run some commands, I want to automate the whole process... is there a way???? Raghu	[reply]
Re^2: Replying to prompts in an automated script by marto (Cardinal) on Dec 10, 2008 at 11:43 UTC
You could use Net::Telnet (keep in mind Telnet - Security) within a script to connect to each server and execute the commands you need to. If you need help installing modules see Installing Modules from the tutorials section of this site. Martin	[reply]