Platform-agnostic shell commands in Terraform

sample.tf

locals {
  # Directories start with "C:..." on Windows; All other OSs use "/" for root.
  is_windows = substr(pathexpand("~"), 0, 1) == "/" ? false : true
}
resource "null_resource" "cli_command" {
  provisioner "local-exec" {
    # Keep as-is. This ensures windows always uses PowerShell, linux/mac use their default shell.
    interpreter = local.is_windows ? ["PowerShell", "-Command"] : []
    # TODO: Replace the below with the windows and linux variants
    command     = local.is_windows ? "sleep 60" : "sleep 60"
  }
  triggers = {
    # TODO: Replace this psuedocode with the trigger that indicates (when changed)
    #       that the command should be re-executed.
    "test_a" = resource.my_resource.sample
  }
}

Also here: https://stackoverflow.com/questions/52628749/set-terraform-default-interpreter-for-local-exec/61392460#61392460