aws iam put-user-permissions-boundary
Adds or updates the policy that is specified as the IAM user's permissions boundary. AWS CLI reference
2 options Its page in the AWS CLI reference
Options
--permissions-boundaryThe ARN of the managed policy that is used to set the permissions boundary for the user.--user-nameThe name (friendly name, not ARN) of the IAM user for which you want to set the permissions boundary.