shfmt(1) General Commands Manual shfmt(1)

shfmt - Format shell programs

shfmt [flags] [path...]

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.

-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).

--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.

-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.

-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.

-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.

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 any option:

[*.sh]
# like -i=4
indent_style = space
indent_size = 4
# --language-variant
shell_variant      = posix
binary_next_line   = true
# --case-indent
switch_case_indent = true
space_redirects    = true
keep_padding       = true
# --func-next-line
function_next_line = 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]]` or `[[bash]]` to match any shell or bash 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

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>.

2024-02-18