Markdownlint

Lint Markdown files for style and consistency using markdownlint via the markdownlint-cli2 CLI.

Running the linter

Lint specific files or directories:

npx markdownlint-cli2 "docs/**/*.md"

Lint and auto-fix fixable issues:

npx markdownlint-cli2 --fix "docs/**/*.md"

Lint multiple paths:

npx markdownlint-cli2 "docs/**/*.md" "README.md" "CHANGELOG.md"

Exclude paths with # (negation):

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

Exit codes

• •0: No errors (warnings may exist)
• •1: Linting errors found
• •2: Linting failed (e.g., bad config)

Interpreting output

Output format: filepath:line rule/alias description

Example:

docs/guide.md:15 MD022/blanks-around-headings [Expected: 1; Actual: 0; Below]
docs/guide.md:42 MD034/no-bare-urls Bare URL used [Context: "..."]

Configuration

Project config file .markdownlint.json

{
  "default": true,
  "MD013": false,
  "MD033": { "allowed_elements": ["details", "summary", "br"] },
  "MD024": { "siblings_only": true }
}

Rules can be set to:

• •true or "error" — enable as error
• •"warning" — enable as warning
• •false — disable
• •{ ... } — enable with parameters

CLI config file .markdownlint-cli2.jsonc

Controls both rules and CLI behavior:

{
  "config": {
    "default": true,
    "MD013": false
  },
  "globs": ["**/*.md"],
  "ignores": ["node_modules/**", "build/**"],
  "fix": false
}

Configuration precedence

1. •.markdownlint-cli2.jsonc / .markdownlint-cli2.yaml (full CLI config)
2. •.markdownlint.jsonc / .markdownlint.json / .markdownlint.yaml (rules only)
3. •Inline HTML comment directives in the file itself

Inline directives

Control rules within a file using HTML comments:

<!-- markdownlint-disable MD013 -->
This long line won't trigger a warning because MD013 is disabled for this section of the file.
<!-- markdownlint-enable MD013 -->

<!-- markdownlint-disable-line MD034 -->
https://bare-url-allowed-on-this-line.com

<!-- markdownlint-disable-next-line MD041 -->
Not a heading on line 1

<!-- markdownlint-configure-file { "MD013": { "line_length": 120 } } -->

State capture/restore:

<!-- markdownlint-capture -->
<!-- markdownlint-disable MD013 -->
Long content here...
<!-- markdownlint-restore -->

Common rules quick reference

For a complete reference of all 47 rules with parameters, see references/rules.md.

Workflow

When creating or editing markdown files:

1. •Write or edit the markdown content
2. •Run the linter: npx markdownlint-cli2 "path/to/file.md"
3. •If errors are found:
   • •Try auto-fix first: npx markdownlint-cli2 --fix "path/to/file.md"
   • •Manually fix any remaining non-fixable issues
   • •Re-run the linter to confirm zero errors
4. •If a rule should be permanently disabled, update .markdownlint.json
5. •For one-off exceptions, use inline directives

Tips

• •Run --fix before manual fixes to save effort — about half the rules are auto-fixable
• •Use rule aliases (e.g., no-trailing-spaces) instead of codes (e.g., MD009) in inline directives for readability
• •The MD013 line-length rule is commonly disabled in projects (this project disables it in .markdownlint.json)
• •Use <!-- markdownlint-disable-next-line --> for single-line exceptions rather than disable/enable blocks
• •Configuration in .markdownlint.json applies to the directory and all subdirectories