This assumes you have already configured the aws command line tool. If not, check out my article on Getting Started with the AWS CLI.

The aws ec2 describe-instances command can be used to list your EC2 instances.

aws ec2 describe-instances

--filter can be used to only return the JSON for an specific instance.

aws ec2 describe-instances --filters "Name=tag:Name,Values=my-instance"

Or like this.

aws ec2 describe-instances --filters "Name=tag-value,Values=my-instance"

Something like this should be returned.

{
    "Reservations": [
        {
            "Instances": [
                {
                    "InstanceId": "i-09123475cf14abcd2",

Using the InstanceId, the aws ec2 get-console-output command can be used to return the EC2 instance logs.

aws ec2 get-console-output --instance-id i-00b0224f78537de3c

Often, --output text is included to return the output separated with newlines.

aws ec2 get-console-output --instance-id i-00b0224f78537de3c --output text