dprint-plugin-shfmt

Wrapper for shfmt for use as a formatting plugin in dprint. It formats shell scripts (POSIX shell, Bash, mksh, Bats and Zsh) exactly like the shfmt CLI does, since it's shfmt's own Go code compiled to Wasm with TinyGo.

Install

Install and setup dprint.

Then in your project's directory with a dprint.json file, run:

dprint add shfmt

Note: You do not need shfmt installed globally as dprint will run shfmt from the .wasm file in a sandboxed environment.

Configuration

Works with no configuration by default. To add configuration, specify a "shfmt" key in your dprint.json:

{
  "shfmt": {
    "useTabs": false,
    "indentWidth": 2,
    "binaryNextLine": true,
    "switchCaseIndent": true,
  },
  "plugins": [
    // ...etc...
  ],
}

The options are shfmt's formatting flags:

Option	shfmt flag	Default	Description
dialect	-ln	auto	auto, bash, posix, mksh, bats or zsh.
useTabs	-i 0	true	Indent with tabs. Uses the global useTabs when not specified.
indentWidth	-i	2	Spaces per indent when not using tabs. Uses the global indentWidth when not specified.
binaryNextLine	-bn	false	Binary operators like && and | may start a line.
switchCaseIndent	-ci	false	Indent the patterns of a case statement.
spaceRedirects	-sr	false	Follow redirect operators with a space (ex. > file).
functionNextLine	-fn	false	Put the opening brace of a function on the next line.
simplify	-s	false	Simplify the code.
minify	-mn	false	Minify the code, which removes comments. Like -mn, it implies simplify.

-kp (keep padding) isn't supported. shfmt deprecated it, and its output with it isn't stable, which dprint reports as an error. shfmt reads its options from EditorConfig files when it's given no flags, but the plugin can't read files, so set them in your dprint config instead.

For an overview of the config, see https://dprint.dev/plugins/shfmt/config/

Dialect

With the default dialect of auto, the dialect is picked like shfmt does:

1. Shell config files: .bashrc, .bash_profile and .bash_logout are Bash, and .zshrc, .zshenv, .zprofile, .zlogin and .zlogout are Zsh.
2. The file extension: .bash, .mksh, .bats and .zsh. A .sh file doesn't count, since its shebang could say Bash.
3. The shebang (ex. #!/bin/sh is POSIX shell).
4. Otherwise, Bash.

Files

The plugin formats the same files shfmt finds when walking a directory: .sh, .bash, .mksh, .bats and .zsh files, along with the shell config files above. To format scripts without an extension, use dprint's shebangs configuration.

JS Formatting API

• JS Formatter - Browser/Deno and Node
• npm package

Versioning

This repo automatically upgrades to the latest version of shfmt once a day. You can check which version of shfmt is being used by looking at the mvdan.cc/sh/v3 entry in the go.mod file in this repo:

https://github.com/dprint/dprint-plugin-shfmt/blob/main/go.mod

At the moment, the version of this plugin does not reflect the version of shfmt.

Development

The plugin is built with TinyGo, which produces a much smaller module than the Go compiler, and one that has no imports, so it doesn't rely on the dprint CLI providing WASI.

go test ./...
deno run -A ./scripts/build.ts # outputs target/plugin.wasm

The build uses a local tinygo (which needs binaryen's wasm-opt) when there is one, and otherwise the TinyGo Docker image.

Credits

• shfmt by Daniel Martí, under the BSD 3-Clause license.
• The plugin interface is adapted from Jake Bailey's dprint-plugin-gofumpt.

License

This project is licensed under the MIT License - see the LICENSE file for details. See third_party for the licenses of the code it includes.