mvdan / sh

sh A shell parser, formatter, and interpreter. Supports [POSIX Shell], [Bash], [Zsh], and [mksh]. Requires Go 1.25 or later. Quick start To parse shell scripts, inspect them, and print them out, see the syntax package. For high-level operations like performing shell expansions on strings, see the shell package. To interpret or run shell scripts, see the interp package. shfmt go install mvdan.cc/sh/v3/cmd/shfmt@latest formats shell programs. See canonical.sh for a quick look at its default style. For example: shfmt -l -w script.sh For more information, see its manpage, which can be viewed directly as Markdown or rendered with [scdoc]. Packages are available on [Alpine], [Arch], [Debian], [Docker], [Fedora], [FreeBSD], [Homebrew], [MacPorts], [NixOS], [OpenSUSE], [Scoop], [Snapcraft], [Void] and [webi]. gosh go install mvdan.cc/sh/v3/cmd/gosh@latest Proof of concept shell that uses the package. Fuzzing We use Go's native fuzzing support. For instance: cd syntax go test -run=- -fuzz=ParsePrint Caveats • When indexing Bash associative arrays, always use quotes. The static parser will otherwise have to assume that the index is an arithmetic expression. • and ambiguity is not supported. Backtracking would complicate the parser and make streaming support via impossible. The POSIX spec recommends to [space the operands][posix-ambiguity] if is meant. • , , and are parsed as keywords. This allows statically building their syntax tree, as opposed to keeping the arguments as a slice of words. It is also required to support . • The entire library is written in pure Go, which limits how closely the interpreter can follow POSIX Shell and Bash semantics. For example, Go does not support forking its own process, so subshells use a goroutine instead, meaning that real PIDs and file descriptors cannot be used directly. Formatting FAQs • The formatter cannot be disabled for ranges of lines; most users wanting this are working around a bug or they don't like how a piece of code is formatted. Instead, search the issue tracker and file a new issue if necessary. Formatting of partial files leads to lots of edge cases and complexity which this project has no resources for, nor interest in, getting into. • We avoid adding more formatting options where possible. Each added flag interacts with all others, multiplying the human cost of development, maintenance, testing, and properly documenting the behavior for end users. • The true value in a formatter is consistency, especially for teams of developers. We do not aim to satisfy every developer's personal choice of optimal formatting. JavaScript The parser and formatter are available as a third party npm package called [sh-syntax], which bundles a version of this library compiled to WASM. Previously, we maintained an npm package called [mvdan-sh] which used GopherJS to bundle a JS version of this library. That npm package is now archived given its poor performance and GopherJS not being as actively developed. Any existing or new users should look at [sh-syntax] instead. Docker All release tags are published via [Docker], such as . The latest stable release is currently published as , and the latest development version as . The images only include ; variants exist on Alpine Linux. To build a Docker image, run: docker build -t my:tag -f cmd/shfmt/Dockerfile . To use a Docker image, run: docker run --rm -u "$(id -u):$(id -g)" -v "$PWD:/mnt" -w /mnt my:tag Related projects The following editor integrations wrap : • [BashSupport-Pro] - Bash plugin for JetBrains IDEs • [dockerfmt] - Dockerfile formatter using shfmt • [intellij-shellscript] - Intellij Jetbrains plugin • [micro] - Editor with a built-in plugin • [neoformat] - (Neo)Vim plugin • [shell-format] - VS Code plugin • [vscode-shfmt] - VS Code plugin • [shfmt.el] - Emacs package • [Sublime-Pretty-Shell] - Sublime Text 3 plugin • [Trunk] - Universal linter, available as a CLI, VS Code plugin, and GitHub action • [vim-shfmt] - Vim plugin Other noteworthy integrations include: • [modd] - A developer tool that responds to filesystem changes • [prettier-plugin-sh] - [Prettier] plugin using [sh-syntax] • [sh-checker] - A GitHub Action that performs static analysis for shell scripts • [mdformat-shfmt] - [mdformat] plugin to format shell scripts embedded in Markdown with shfmt • [pre-commit-shfmt] - [pre-commit] shfmt hook • [tesh] - Run scripts with mocks, assertions, and coverage [alpine]: https://pkgs.alpinelinux.org/packages?name=shfmt [arch]: https://archlinux.org/packages/extra/x86_64/shfmt/ [bash]: https://www.gnu.org/software/bash/ [BashSupport-Pro]: https://www.bashsupport.com/manual/editor/formatter/ [debian]: https://tracker.debian.org/pkg/golang-mvdan-sh [docker]: https://hub.docker.com/r/mvdan/shfmt/ [dockerfmt]: https://github.com/reteps/dockerfmt [editorconfig]: https://editorconfig.org/ [examples]: https://pkg.go.dev/mvdan.cc/sh/v3/syntax#pkg-examples [fedora]: https://packages.fedoraproject.org/pkgs/golang-mvdan-sh-3/shfmt/ [freebsd]: https://www.freshports.org/devel/shfmt [homebrew]: https://formulae.brew.sh/formula/shfmt [intellij-shellscript]: https://www.jetbrains.com/help/idea/shell-scripts.html [macports]: https://ports.macports.org/port/shfmt/details/ [mdformat-shfmt]: https://github.com/hukkin/mdformat-shfmt [mdformat]: https://github.com/executablebooks/mdformat [micro]: https://micro-editor.github.io/ [mksh]: http://www.mirbsd.org/mksh.htm [modd]: https://github.com/cortesi/modd [mvdan-sh]: https://www.npmjs.com/package/mvdan-sh [neoformat]: https://github.com/sbdchd/neoformat [nixos]: https://github.com/NixOS/nixpkgs/blob/HEAD/pkgs/tools/text/shfmt/default.nix [OpenSUSE]: https://build.opensuse.org/package/show/openSUSE:Factory/shfmt [posix shell]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html [posix-ambiguity]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_03 [pre-commit]: h…