You can get help with any command when using the AWS Command Line Interface
(AWS CLI). To do so, simply type
help at the end of a command name.
For example, the following command displays help for the general AWS CLI options and the available top-level commands.
$ aws help
The following command displays the available Amazon Elastic Compute Cloud (Amazon EC2) specific commands.
$ aws ec2 help
The following example displays detailed help for the Amazon EC2 ‘DescribeInstances’ operation. The help includes descriptions of its input parameters, available filters, and what is included as output. It also includes examples showing how to type common variations of the command.
$ aws ec2 describe-instances help