バージョンアップ
$ wget https://releases.hashicorp.com/terraform/0.12.21/terraform_0.12.21_linux_amd64.zip -O /tmp/terraform_0.12.21_linux_amd64.zip
$ unzip /tmp/terraform_0.12.21_linux_amd64.zip
$ sudo unlink /usr/local/bin/terraform
$ sudo mv terraform /usr/local/bin/terraform_0.12.21
$ sudo ln -s /usr/local/bin/terraform_0.12.21 /usr/local/bin/terraform
$ terraform version
Terraform v0.12.21