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 files 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, --list
    List files whose formatting differs from shfmt's.

-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.

-s, --simplify
    Simplify the code.

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

  Parser flags

-ln, --language-dialect <str>
    Language dialect (bash/posix/mksh/bats, 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 overriden by a valid shell shebang.

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

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

  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.

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

  Utility flags

-f, --find
    Recursively find all shell files and print the paths.

--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/shell.xml>:

    shfmt -i 2 -ci -bn

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

    [*.sh]
    # like -i=4
    indent_style = space
    indent_size = 4
    shell_variant      = posix # --language-variant
    binary_next_line   = true
    switch_case_indent = true  # --case-indent
    space_redirects    = true
    keep_padding       = true
    function_next_line = true  # --func-next-line
    # Ignore the entire "third_party" directory.
    [third_party/**]
    ignore = true

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>.