markdownlint-cli2

A fast, flexible, configuration-based command-line interface for linting Markdown/CommonMark files with the markdownlint library

Install

As a global CLI:

npm install markdownlint-cli2 --global

As a development dependency of the current Node.js package:

npm install markdownlint-cli2 --save-dev

As a Docker container image:

docker pull davidanson/markdownlint-cli2

As a global CLI with Homebrew:

brew install markdownlint-cli2

As a GitHub Action via markdownlint-cli2-action:

- name: markdownlint-cli2-action
  uses: DavidAnson/markdownlint-cli2-action@main

Overview

markdownlint is a library for linting Markdown/ CommonMark files on Node.js using the markdown-it parser.
markdownlint-cli is a traditional command-line interface for markdownlint.
markdownlint-cli2 is a slightly unconventional command-line interface for markdownlint.
markdownlint-cli2 is configuration-based and prioritizes speed and simplicity.
markdownlint-cli2 supports all the features of markdownlint-cli (sometimes a little differently).
vscode-markdownlint is a markdownlint extension for the Visual Studio Code editor.
markdownlint-cli2 is designed to work well in conjunction with vscode-markdownlint.
More about the motivation for markdownlint-cli2.

Use

Command Line

markdownlint-cli2 vX.Y.Z (markdownlint vX.Y.Z)
https://github.com/DavidAnson/markdownlint-cli2

Syntax: markdownlint-cli2 glob0 [glob1] [...] [globN] [--config file] [--fix] [--format] [--help] [--no-globs]

Glob expressions (from the globby library):
- * matches any number of characters, but not /
- ? matches a single character, but not /
- ** matches any number of characters, including /
- {} allows for a comma-separated list of "or" expressions
- ! or # at the beginning of a pattern negate the match
- : at the beginning identifies a literal file path
- - as a glob represents standard input (stdin)

Dot-only glob:
- The command "markdownlint-cli2 ." would lint every file in the current directory tree which is probably not intended
- Instead, it is mapped to "markdownlint-cli2 *.{md,markdown}" which lints all Markdown files in the current directory
- To lint every file in the current directory tree, the command "markdownlint-cli2 **" can be used instead

Optional parameters:
- --config    specifies the path to a configuration file to define the base configuration
- --fix       updates files to resolve fixable issues (can be overridden in configuration)
- --format    reads standard input (stdin), applies fixes, writes standard output (stdout)
- --help      writes this message to the console and exits without doing anything else
- --no-globs  ignores the "globs" property if present in the top-level options object

Configuration via:
- .markdownlint-cli2.jsonc
- .markdownlint-cli2.yaml
- .markdownlint-cli2.cjs or .markdownlint-cli2.mjs
- .markdownlint.jsonc or .markdownlint.json
- .markdownlint.yaml or .markdownlint.yml
- .markdownlint.cjs or .markdownlint.mjs
- package.json

Cross-platform compatibility:
- UNIX and Windows shells expand globs according to different rules; quoting arguments is recommended
- Some Windows shells don't handle single-quoted (') arguments well; double-quote (") is recommended
- Shells that expand globs do not support negated patterns (!node_modules); quoting is required here
- Some UNIX shells parse exclamation (!) in double-quotes; hashtag (#) is recommended in these cases
- The path separator is forward slash (/) on all platforms; backslash (\) is automatically converted
- On any platform, passing the parameter "--" causes all remaining parameters to be treated literally

The most compatible syntax for cross-platform support:
$ markdownlint-cli2 "**/*.md" "#node_modules"

For scenarios where it is preferable to specify glob expressions in a configuration file, the globs property of .markdownlint-cli2.jsonc, .yaml, .cjs, or .mjs may be used instead of (or in addition to) passing glob0 ... globN on the command-line.

As shown above, a typical command-line for markdownlint-cli2 looks something like:

markdownlint-cli2 "**/*.md" "#node_modules"

Because sharing the same configuration between "normal" and "fix" modes is common, the --fix argument can be used to default the fix property (see below) to true (though it can still be overridden by a configuration file):

markdownlint-cli2 --fix "**/*.md" "#node_modules"

In cases where it is not convenient to store a configuration file in the root of a project, the --config argument can be used to provide a path to any supported configuration file (except package.json):

markdownlint-cli2 --config "config/.markdownlint-cli2.jsonc" "**/*.md" "#node_modules"

The configuration file name must be (or end with) one of the supported names above. For example, .markdownlint.json or example.markdownlint-cli2.jsonc. The specified configuration file will be loaded, parsed, and applied as a base configuration for the current directory - which will then be handled normally.

Container Image

A container image davidanson/markdownlint-cli2 can also be used (e.g., as part of a CI pipeline):

docker run -v $PWD:/workdir davidanson/markdownlint-cli2:v0.19.0 "**/*.md" "#node_modules"

Notes:

As when using the command line, glob patterns are passed as arguments.
This image is built on the official Node.js Docker image. Per security best practices, the default user node runs with restricted permissions. If it is necessary to run as root, pass the -u root option when invoking docker.
By default, markdownlint-cli2 will execute within the /workdir directory inside the container. So, as shown above, bind mount the project's directory there.
- A custom working directory can be specified with Docker's -w flag:
```
docker run -w /myfolder -v $PWD:/myfolder davidanson/markdownlint-cli2:v0.19.0 "**/*.md" "#node_modules"
```

For convenience, the container image davidanson/markdownlint-cli2-rules includes the latest versions of custom rules published to npm with the tag markdownlint-rule. These rules are installed globally onto the base image davidanson/markdownlint-cli2.

Note: This container image exists for convenience and is not an endorsement of the rules within.

Output Formatters

In addition to (or instead of) the default behavior of writing a list of all issues to the standard error (stderr) device, custom output formatters can be configured to produce a variety of outputs like:

List of issues (default)
List of issues with color and links
GitLab Code Quality report file
JSON file
JUnit XML file
Static Analysis Results Interchange Format/SARIF file
Summary of issues found
Flexible string template supporting:
- Azure Pipelines Task command LogIssue format
- GitHub Actions workflow commands format

For more information, refer to the documentation for the outputFormatters parameter below.

Exit Codes

0: Linting was successful and there were no errors (there may be warnings)
1: Linting was successful and there were errors (and possibly warnings)
2: Linting was not successful due to a problem or failure

Formatting

Some editors implement document formatting by invoking an external program, passing the text of the current document on standard input (stdin), and reading the formatted result from standard output (stdout). This scenario is supported by the --format command-line parameter. When --format is set:

Globs and other input sources are ignored
The --fix parameter is implicitly set
The exit code 1 is not used

Rule List

See the Rules / Aliases and Tags sections of the markdownlint documentation.

Glob expressions

Globbing is performed by the globby library; refer to that documentation for more information and examples.

Configuration

See the Configuration section of the markdownlint documentation for information about the inline comment syntax for enabling and disabling rules with HTML comments.
In general, glob expressions should match files under the current directory; the configuration for that directory will apply to the entire tree.
- When glob expressions match files not under the current directory, configuration for the current directory is applied to the closest common parent directory.
Paths beginning with ~ are resolved relative to the user's home directory (typically $HOME on UNIX and %USERPROFILE% on Windows)
There are two kinds of configuration file (both detailed below):
- Configuration files like .markdownlint-cli2.* allow complete control of markdownlint-cli2 behavior and are also used by vscode-markdownlint.
  - If multiple of these files are present in the same directory, only one is used according to the following precedence:
    1. .markdownlint-cli2.jsonc
    2. .markdownlint-cli2.yaml
    3. .markdownlint-cli2.cjs
    4. .markdownlint-cli2.mjs
    5. package.json (only supported in the current directory)
- Configuration files like .markdownlint.* allow control over only the markdownlint config object and tend to be supported more broadly (such as by markdownlint-cli).
  - If multiple of these files are present in the same directory, only one is used according to the following precedence:
    1. .markdownlint.jsonc
    2. .markdownlint.json
    3. .markdownlint.yaml
    4. .markdownlint.yml
    5. .markdownlint.cjs
    6. .markdownlint.mjs
The VS Code extension includes a JSON Schema definition for the JSON(C) configuration files described below. This adds auto-complete and can make it easier to define proper structure.
See markdownlint-cli2-config-schema.json for that schema and ValidatingConfiguration.md for ways to use it to validate configuration files.