Getting ID of an instance newly launched with ec2-api-tools

Question

I'm launching an EC2 instance, by invoking ec2-run-instances from simple a bash script, and want to perform further operations on that instance (e.g. associate elastic IP), for which I need the instance id.

The command is something like ec2-run-instances ami-dd8ea5a9 -K pk.pem -C cert.pem --region eu-west-1 -t c1.medium -n 1, and its output:

RESERVATION r-b6ea58c1    696664755663    default
INSTANCE    i-945af9e3    ami-dd8ea5b9    pending    0    c1.medium    2010-04-15T10:47:56+0000    eu-west-1a    aki-b02a01c4    ari-39c2e94d   

In this example, i-945af9e3 is the id I'm after.

So, I'd need a simple way to parse the id from what the command returns - how would you go about doing it? My AWK is a little rusty... Feel free to use any tool available on a typical Linux box. (If there's a way to get it directly using EC2-API-tools, all the better. But afaik there's no EC2 command to e.g. return the id of the most recently launched instance.)

Answer 1

Ok, at least something like this should work:

instance_id=$(ec2-run-instances ami-dd8ea5a9 [...] | awk '/INSTANCE/{print $2}') 

Admittedly I was a bit lazy thinking that it's quicker to ask on SO than to relearn some AWK basics... :-)

Edit: simplified AWK usage as Dennis suggested. Also, using $() instead of `` for clarity, and got rid of intermediate variable.