dotenv-linter-cli

Lint .env files for common mistakes — zero dependencies, pure Node.js.

Install

npm install -g dotenv-linter-cli

Or run without installing:

npx dotenv-linter-cli

Usage

dotenv-lint [options] [file...]

By default lints .env in the current directory.

dotenv-lint                        # lint .env
dotenv-lint .env.production        # lint a specific file
dotenv-lint .env .env.local        # lint multiple files
dotenv-lint --fix .env             # auto-fix fixable issues
dotenv-lint --strict .env          # enforce uppercase keys + quote consistency
dotenv-lint --json .env            # JSON output (for CI / tooling)

Rules

| Rule | Severity | Description | |------|----------|-------------| | DUPLICATE_KEY | ERROR | Same key defined more than once | | SPACES_AROUND_EQ | ERROR | KEY = value instead of KEY=value | | MISSING_EQ | ERROR | Line has a key-like word but no = sign | | EMPTY_VALUE | WARNING | KEY= with nothing after the equals sign | | INVALID_CASE | WARNING | Key contains lowercase letters | | MIXED_QUOTES | WARNING | Inconsistent quote style across values (--strict only) |

Example output

Linting: .env (12 lines)

  Line    3  ERROR    DUPLICATE_KEY    KEY "DATABASE_URL" defined twice (first at line 1)
  Line    7  WARNING  EMPTY_VALUE      KEY "SECRET_KEY" has empty value
  Line    9  WARNING  INVALID_CASE     KEY "api_key" should be uppercase: API_KEY
  Line   11  ERROR    SPACES_AROUND_EQ Use KEY=value, not KEY = value

4 issues (2 errors, 2 warnings)

Flags

| Flag | Description | |------|-------------| | --fix | Auto-fix: remove spaces around =, deduplicate keys (keeps last definition) | | --strict | Also enforce UPPERCASE keys and consistent quote style | | --json | Output a JSON array of { file, line, key, rule, severity, message } | | --help / -h | Show help | | --version / -v | Show version |

Exit codes

| Code | Meaning | |------|---------| | 0 | No issues | | 1 | Warnings only | | 2 | At least one error |

CI integration

# GitHub Actions example
- name: Lint .env files
  run: npx dotenv-linter-cli --json .env | tee lint-results.json

License

MIT