Which command initializes a directory containing Terraform configuration files?

The command that initializes a directory containing Terraform configuration files is "terraform init." This command is essential for setting up the working environment for Terraform operations. It prepares the directory by downloading the required provider plugins and setting up the backend for state storage.

When you run this command, Terraform creates a .terraform directory where it stores the plugin binaries and other necessary metadata. It also verifies that all required provider configurations are valid and can communicate with their respective services. This ensures that when you subsequently run commands like terraform plan or terraform apply, Terraform has everything it needs to understand and manage your infrastructure.

The other options serve different purposes within the Terraform workflow. For example, "terraform apply" is used to create or update infrastructure according to the configuration files but requires that the environment has already been initialized. "terraform plan" generates an execution plan indicating what actions Terraform will take to reach the desired state but also assumes that initialization has already been performed. Lastly, "terraform destroy" is used to remove all the infrastructure managed by Terraform in the current configuration, which again, relies on prior initialization to function correctly.