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Command: fmt

The tofu fmt command is used to rewrite OpenTofu configuration files to a canonical format and style. This command applies a subset of the OpenTofu language style conventions, along with other minor adjustments for readability.

Other OpenTofu commands that generate OpenTofu configuration will produce configuration files that conform to the style imposed by tofu fmt, so using this style in your own files will ensure consistency.

The canonical format may change in minor ways between OpenTofu versions, so after upgrading OpenTofu we recommend to proactively run tofu fmt on your modules along with any other changes you are making to adopt the new version.

We don't consider new formatting rules in tofu fmt to be a breaking change in new versions of OpenTofu, but we do aim to minimize changes for configurations that are already following the style examples shown in the OpenTofu documentation. When adding new formatting rules, they will usually aim to apply more of the rules already shown in the configuration examples in the documentation, and so we recommend following the documented style even for decisions that tofu fmt doesn't yet apply automatically.

Formatting decisions are always subjective and so you might disagree with the decisions that tofu fmt makes. This command is intentionally opinionated and has no customization options because its primary goal is to encourage consistency of style between different OpenTofu codebases, even though the chosen style can never be everyone's favorite.

We recommend that you follow the style conventions applied by tofu fmt when writing OpenTofu modules, but if you find the results particularly objectionable then you may choose not to use this command, and possibly choose to use a third-party formatting tool instead. If you choose to use a third-party tool then you should also run it on files that are generated automatically by OpenTofu, to get consistency between your hand-written files and the generated files.


Usage: tofu fmt [options] [target...]

By default, fmt scans the current directory for configuration files. If you provide a directory for the target argument, then fmt will scan that directory instead. If you provide a file, then fmt will process just that file. If you provide a single dash (-), then fmt will read from standard input (STDIN).

The command-line flags are all optional. The following flags are available:

  • -list=false - Don't list the files containing formatting inconsistencies.
  • -write=false - Don't overwrite the input files. (This is implied by -check or when the input is STDIN.)
  • -diff - Display diffs of formatting changes.
  • -check - Check if the input is formatted. Exit status will be 0 if all input is properly formatted. If not, exit status will be non-zero and the command will output a list of filenames whose files are not properly formatted.
  • -recursive - Also process files in subdirectories. By default, only the given directory (or current directory) is processed.