如何在 bash 的变量中捕获 output 文本值

Question

I'm running this command for getting the public IP of an EC2. It works as expected!

aws ec2 describe-instances --filters "Name=tag:Name,Values=EC2" --query 'Reservations[*].Instances[*].PublicIpAddress' --output text

I'm trying to use this value for running this command, so instead of XX.XX.XX.XX it has to be the value I get from ec2 describe-instances ansible-playbook provisioning/site.yml -i inventory --ssh-common-args '-o "proxycommand ssh -W %h:%p -i Key.pem ubuntu@XX.XX.XX.XX"'

So I have my commands like this

IP=aws ec2 describe-instances --filters "Name=tag:Name,Values=$NAME_PREFIX*" --query 'Reservations[*].Instances[*].PublicIpAddress' --output text
export BASTION="ubuntu@${IP}"
ansible-playbook provisioning/site.yml -i inventory --ssh-common-args '-o "proxycommand ssh -W %h:%p -i Key.pem ${BASTION}"'

So not sure, how should I use that output, if you could help me please

Answer 1

It is better to add "Name=instance-state-name,Values=running" clause in filters to make sure you get a running instance only so your aws command would be:

aws ec2 describe-instances --filters "Name=instance-state-name,Values=running" "Name=tag:Name,Values=$NAME_PREFIX*" --query 'Reservations[*].Instances[*].PublicIpAddress' --output text

Now to store output IP in a variable, you can use command substitution:

ip=$(aws ec2 describe-instances --filters "Name=instance-state-name,Values=running" "Name=tag:Name,Values=$NAME_PREFIX*" --query 'Reservations[*].Instances[*].PublicIpAddress' --output text)

Then to use it:

export BASTION="ubuntu@$ip"
ansible-playbook provisioning/site.yml -i inventory --ssh-common-args '-o "proxycommand ssh -W %h:%p -i Key.pem '"$BASTION"'"'