dotenv-linter can check / fix / compare .env files for problems that may cause the application to malfunction. Available checks: ✅ Duplicated key ✅ Ending blank line ✅ Extra blank line ✅ Incorrect delimiter ✅ Key without value ✅ Leading character ✅ Lowercase key ✅ Quote character ✅ Space character ✅ Substitution key ✅ Trailing whitespace ✅ Unordered key ✅ Value without quotes What is a .env file?