1. Install unzip

sudo apt-get install unzip

2. Confirm the latest version number on the terraform website:

https://www.terraform.io/downloads.html

3. Download latest version of the terraform (substituting newer version number if needed)

wget https://releases.hashicorp.com/terraform/0.12.18/terraform_0.12.18_linux_amd64.zip

4. Extract the downloaded file archive

unzip terraform_0.12.18_linux_amd64.zip

5. Move the executable into a directory searched for executables

sudo mv terraform /usr/local/bin/

6. Run it

terraform --version