Let's say you have the following files on your Terraform server.

├── required_providers.tf
├── iam (directory)
│   ├── data.tf
│   ├── outputs.tf
│   ├── provider.tf

required_providers.tf will almost always have this.

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
    }
  }
}

Let's say provider.tf has the following. In this example, the "default" profile in /home/username/.aws/config and /home/username/.aws/credentials is being used. This assumes you have setup Terraform as described in Amazon Web Services (AWS) - Getting Started with Terraform.

provider "aws" {
  alias   = "default"
  profile = "default"
  region  = "default"
}

And data.tf could have something like this.

data "aws_caller_identity" "caller-identity" {}

And outputs.tf could have something like this.

output "caller_identity" {
  value = data.aws_caller_identity.caller-identity
}

The terraform refresh command should output something like this.

caller_identity = {
  "account_id" = "123456789012"
  "arn" = "arn:aws:iam::123456789012:user/johndoe"
  "id" = "123456789012"
  "user_id" = "AIABDEFG76GL123456RP"
}