shfmt(1)

NAME

shfmt - Format shell programs

SYNOPSIS

shfmt [flags] [path...]

DESCRIPTION

shfmt formats shell programs. If the only argument is a dash (-) or no arguments are given, standard input will be used. If a given path is a directory, all shell scripts found under that directory will be used.

If any EditorConfig files are found, they will be used to apply formatting options. If any parser or printer flags are given to the tool, no EditorConfig formatting options will be used. A default like -i=0 can be used for this purpose.

shfmt's default shell formatting was chosen to be consistent, common, and predictable. Some aspects of the format can be configured via printer flags.

OPTIONS

  Generic flags

--version
    Show version and exit.

-l[=0], --list[=0]
    Error with a list of files whose formatting differs from shfmt; paths are separated by a newline or a null character if -l=0

-w, --write
    Write result to file instead of stdout.

-d, --diff
    Error with a diff when the formatting differs.

    The diff uses color when the output is a terminal. To never use color, set a non-empty NO_COLOR or TERM=dumb. To always use color, set a non-empty FORCE_COLOR.

--apply-ignore
    Always apply EditorConfig ignore rules.

    When formatting files directly, ignore rules are skipped without this flag. Should be useful to any tools or editors which format stdin or a single file. When printing results to stdout, an ignored file results in no output at all.

--detect <str>
    How to detect shell files when walking directories or via --find: default, exec, or all.

    By default, files with a non-shell extension like foo.go are skipped; only shell extensions like foo.sh and extensionless files with a shell shebang are used. exec also reads the shebangs of executable files, costing an extra stat per skipped file, and all reads the shebangs of all regular files.

--filename str
    Provide a name for the standard input file.

    Use of this flag is necessary for EditorConfig support to work with stdin, since EditorConfig files are found relative to the location of a script.

  Parser flags

-ln, --language-dialect <str>
    Language dialect (bash/posix/mksh/bats/zsh, default auto).

    When set to auto, the language is detected from the input filename, as long as it has a shell extension like foo.mksh. Otherwise, if the input begins with a shell shebang like #!/bin/sh, that's used instead. If neither come up with a result, bash is used as a fallback.

    The filename extension .sh is a special case: it implies posix, but may be overridden by a valid shell shebang.

-p, --posix
    Shorthand for -ln=posix.

-s, --simplify
    Simplify the code.

  Printer flags

-i, --indent <uint>
    Indent: 0 for tabs (default), >0 for number of spaces.

-bn, --binary-next-line
    Binary ops like && and | may start a line.

-ci, --case-indent
    Switch cases will be indented.

-sr, --space-redirects
    Redirect operators will be followed by a space.

-kp, --keep-padding
    Keep column alignment paddings.

    This flag is DEPRECATED and will be removed in the next major version. For more information, see: https://github.com/mvdan/sh/issues/658

-fn, --func-next-line
    Function opening braces are placed on a separate line.

-mn, --minify
    Minify the code to reduce its size (implies -s).

  Utility flags

-f[=0], --find[=0]
    Recursively find all shell files and print the paths; paths are separated by a newline or a null character if -f=0.

--to-json
    Print syntax tree to stdout as a typed JSON.

--from-json
    Read syntax tree from stdin as a typed JSON.

EXAMPLES

Format all the scripts under the current directory, printing which are modified:

    shfmt -l -w .

For CI, one can use a variant where formatting changes are just shown as diffs:

    shfmt -d .

The following formatting flags closely resemble Google's shell style defined in <https://google.github.io/styleguide/shellguide.html>:

    shfmt -i 2 -ci -bn

Below is a sample EditorConfig file as defined by <https://editorconfig.org/>, showing how to set supported options:

    [*.sh]
    # like -i=4
    indent_style = space
    indent_size = 4
    # --language-dialect
    shell_variant      = posix
    simplify           = true
    binary_next_line   = true
    # --case-indent
    switch_case_indent = true
    space_redirects    = true
    keep_padding       = true
    # --func-next-line
    function_next_line = true
    minify             = true
    # Ignore the entire "third_party" directory when calling shfmt on directories,
    # such as "shfmt -l -w .". When formatting files directly,
    # like "shfmt -w third_party/foo.sh" or "shfmt --filename=third_party/foo.sh",
    # the ignore logic is applied only when the --apply-ignore flag is given.
    [third_party/**]
    ignore = true

EditorConfig sections may also use `[[shell]]`, `[[bash]]`, or `[[zsh]]` to match shell scripts, which is particularly useful when scripts use a shebang but no extension. Note that this feature is outside of the EditorConfig spec and may be changed in the future.

shfmt can also replace bash -n to check shell scripts for syntax errors. It is more exhaustive, as it parses all syntax statically and requires valid UTF-8:

    $ echo '${foo:1 2}' | bash -n
    $ echo '${foo:1 2}' | shfmt >/dev/null
    1:9: not a valid arithmetic operator: 2
    $ echo 'foo=(1 2)' | bash --posix -n
    $ echo 'foo=(1 2)' | shfmt -p >/dev/null
    1:5: arrays are a bash feature

AUTHORS

Maintained by Daniel Martí <mvdan@mvdan.cc>, who is assisted by other open source contributors. For more information and development, see <https://github.com/mvdan/sh>.