TF_LOG_PATH specifies where the log should persist its output to. Note that even when TF_LOG_PATH is set, TF_LOG must be set in order for any logging to be enabled.
For example, to always write the log to the directory you're currently running terraform from:
export TF_LOG_PATH=./terraform.log
export TF_LOG=TRACE

The terraform init command is used to initialize a working directory containing Terraform configuration files. This is the first command that should be run after writing a new Terraform configuration or cloning an existing one from version control. It is safe to run this command multiple times.
This command is always safe to run multiple times, to bring the working directory up to date with changes in the configuration. Though subsequent runs may give errors, this command will never delete your existing configuration or state.
terraform init command does -
* Copy a Source Module
* Backend Initialization
* Child Module Installation
* Plugin Installation
https://www.terraform.io/docs/commands/init.html

Explanation
https://www.terraform.io/docs/commands/force-unlock.html

Explanation
https://www.terraform.io/docs/commands/state/index.html

Explanation
If a resource successfully creates but fails during provisioning, Terraform will error and mark the resource as
"tainted". A resource that is tainted has been physically created, but can't be considered safe to use since provisioning failed. Terraform also does not automatically roll back and destroy the resource during the apply when the failure happens, because that would go against the execution plan: the execution plan would've said a resource will be created, but does not say it will ever be deleted.