#!/bin/bash
s='provider "aws" {
  region = "${var.region}"

  assume_role {
    role_arn = "${var.role_arn}"
  }
}'
REGION="eu-central-1"
ROLE_ARN="arn:iam:mnsasa:asssasa"
s=$(sed 's/\(region = "\)${var.region}"/\1'"$REGION"'"/g' <<< "$s")
sed 's/\(role_arn = "\)${var.role_arn}"/\1'"$ROLE_ARN"'"/g' <<< "$s"