A shell parser, formatter and interpreter. Supports POSIX Shell, Bash and mksh. Requires Go 1.11 or later.
To parse shell scripts, inspect them, and print them out, see the syntax examples.
For high-level operations like performing shell expansions on strings, see the shell examples.
Go 1.11 and later can download the latest v2 stable release:
cd $(mktemp -d); go mod init tmp; go get mvdan.cc/sh/cmd/shfmt
The latest v3 pre-release can be downloaded in a similar manner, using the /v3
module:
cd $(mktemp -d); go mod init tmp; go get mvdan.cc/sh/v3/cmd/shfmt
shfmt formats shell programs. It can use tabs or any number of spaces to
indent. See canonical.sh for a quick look at its default
style.
You can feed it standard input, any number of files or any number of directories
to recurse into. When recursing, it will operate on .sh and .bash files and
ignore files starting with a period. It will also operate on files with no
extension and a shell shebang.
shfmt -l -w script.sh
Typically, CI builds should use the command below, to error if any shell scripts in a project don't adhere to the format:
shfmt -d .
Use -i N to indent with a number of spaces instead of tabs. There are other
formatting options - see shfmt -h. For example, to get the formatting
appropriate for Google's Style guide, use shfmt -i 2 -ci.
Packages are available on Arch, CRUX, Docker, FreeBSD, Homebrew, NixOS, Scoop, Snapcraft, and Void.
bash -n can be useful to check for syntax errors in shell scripts. However,
shfmt >/dev/null can do a better job as it checks for invalid UTF-8 and does
all parsing statically, including checking POSIX Shell validity:
$ echo '${foo:1 2}' | bash -n
$ echo '${foo:1 2}' | shfmt
1:9: not a valid arithmetic operator: 2
$ echo 'foo=(1 2)' | bash --posix -n
$ echo 'foo=(1 2)' | shfmt -p
1:5: arrays are a bash feature