---
page_title: Writing and Modifying Code - OpenTF CLI
description: >-
  Learn commands that help validate, format, and upgrade code written in the
  OpenTF Configuration Language.
---

# Writing and Modifying OpenTF Code

The [OpenTF language](/opentf/language) is OpenTF's primary
user interface, and all of OpenTF's workflows rely on configurations written
in the OpenTF language.

OpenTF CLI includes several commands to make OpenTF code more convenient
to work with. Integrating these commands into your editing workflow can
potentially save you time and effort.

- [The `opentf console` command](/opentf/cli/commands/console) starts an
  interactive shell for evaluating OpenTF
  [expressions](/opentf/language/expressions), which can be a faster way
  to verify that a particular resource argument results in the value you expect.

- [The `opentf fmt` command](/opentf/cli/commands/fmt) rewrites OpenTF
  configuration files to a canonical format and style, so you don't have to
  waste time making minor adjustments for readability and consistency. It works
  well as a pre-commit hook in your version control system.

- [The `opentf validate` command](/opentf/cli/commands/validate) validates the
  syntax and arguments of the OpenTF configuration files in a directory,
  including argument and attribute names and types for resources and modules.
  The `plan` and `apply` commands automatically validate a configuration before
  performing any other work, so `validate` isn't a crucial part of the core
  workflow, but it can be very useful as a pre-commit hook or as part of a
  continuous integration pipeline.