The override-tf creates override.tf as below,

terraform {
    backend "local" {
    }
}

Generally, Terraform uses remote storage(for example, S3) as a backend for tfstate. But it would make some difficulties if tfstate were updated by some developers. The override.tf overrides backend configuration temporary, and backend for tfstate will be local.

$ go instlall

1. Initialization(Only for first time)

$ terraform init

2. Pull tfstate from remote to local(A file name is arbitrary.)

$ terraform state pull > tmp.tfstate

3. Create override.tf

$ override-tf

4. Override backend config

$ terraform init -reconfigure

A message Successfully configured the backend "local"! will be shown. Then you can use local tfstate file with -state option like below,

$ terraform apply -state=tmp.tfstate