env-cmd

What is env-cmd?

The env-cmd npm package allows you to easily set environment variables from a file or inline before running a command. This is particularly useful for managing different environments (development, testing, production) without hardcoding environment variables in your code.

What are env-cmd's main functionalities?

Load environment variables from a file

This feature allows you to load environment variables from a specified file before running your command. The file should follow the standard .env format.

env-cmd -f ./path/to/.env node app.js

Load environment variables from multiple files

You can load environment variables from multiple files. This is useful for layering configurations, such as having a base configuration and an environment-specific override.

env-cmd -f ./path/to/.env -f ./path/to/.env.local node app.js

Inline environment variables

This feature allows you to set environment variables inline directly in the command. This is useful for quick tests or temporary overrides.

env-cmd -e 'NODE_ENV=production' node app.js

JSON configuration

You can also pass environment variables as a JSON object. This is useful for more complex configurations that might be easier to manage in JSON format.

env-cmd -e '{"NODE_ENV": "production", "API_KEY": "12345"}' node app.js

Other packages similar to env-cmd

dotenv

dotenv is a popular package for loading environment variables from a .env file into process.env. Unlike env-cmd, dotenv is typically used by requiring it in your code, rather than as a command-line tool.

cross-env

cross-env allows you to set environment variables across different platforms (Windows, Linux, macOS) in a consistent manner. It is similar to env-cmd but focuses more on cross-platform compatibility.

dotenv-cli

dotenv-cli is a command-line interface for dotenv, allowing you to load environment variables from a .env file before running a command, similar to env-cmd. It provides a simpler interface but lacks some of the advanced features of env-cmd.

README

env-cmd

A simple node program for executing commands using an environment from an env file.

💾 Install

npm install env-cmd or npm install -g env-cmd

⌨️ Basic Usage

Environment file ./.env

# This is a comment
ENV1=THANKS
ENV2=FOR ALL
ENV3=THE FISH

Package.json

{
  "scripts": {
    "test": "env-cmd -- mocha -R spec"
  }
}

Terminal

./node_modules/.bin/env-cmd -- node index.js

Using custom env file path

To use a custom env filename or path, pass the -f flag. This is a major breaking change from prior versions < 9.0.0

Terminal

./node_modules/.bin/env-cmd -f ./custom/path/.env -- node index.js

📜 Help

Usage: env-cmd [options] -- <command> [...args]

Options:
  -v, --version                 output the version number
  -e, --environments [envs...]  The rc file environment(s) to use
  -f, --file [path]             Custom env file path or .rc file path if '-e' used (default path: ./.env or ./.env-cmdrc.(js|cjs|mjs|json))
  -x, --expand-envs             Replace $var and ${var} in args and command with environment variables
  --recursive                   Replace $var and ${var} in env file with the referenced environment variable
  --fallback                    Fallback to default env file path, if custom env file path not found
  --no-override                 Do not override existing environment variables
  --silent                      Ignore any env-cmd errors and only fail on executed program failure.
  --use-shell                   Execute the command in a new shell with the given environment
  --verbose                     Print helpful debugging information
  -h, --help                    display help for command

🔬 Advanced Usage

.rc file usage

For more complex projects, a .env-cmdrc file can be defined in the root directory and supports as many environments as you want. Simply use the -e flag and provide which environments you wish to use from the .env-cmdrc file. Using multiple environment names will merge the environment variables together. Later environments overwrite earlier ones in the list if conflicting environment variables are found.

.rc file ./.env-cmdrc

{
  "development": {
    "ENV1": "Thanks",
    "ENV2": "For All"
  },
  "test": {
    "ENV1": "No Thanks",
    "ENV3": "!"
  },
  "production": {
    "ENV1": "The Fish"
  }
}

Terminal

./node_modules/.bin/env-cmd -e production -- node index.js
# Or for multiple environments (where `production` vars override `test` vars,
# but both are included)
./node_modules/.bin/env-cmd -e test,production -- node index.js

--no-override option

Prevents overriding of existing environment variables on process.env and within the current environment.

--fallback file usage option

If the .env file does not exist at the provided custom path, then use the default fallback location ./.env env file instead.

--use-shell

Executes the command within a new shell environment. This is useful if you want to string multiple commands together that share the same environment variables.

Terminal

./node_modules/.bin/env-cmd -f ./test/.env --use-shell -- "npm run lint && npm test"

Asynchronous env file support

EnvCmd supports reading from asynchronous .env files. Instead of using a .env file, pass in a .js file that exports either an object or a Promise resolving to an object ({ ENV_VAR_NAME: value, ... }). Asynchronous .rc files are also supported using .js file extension and resolving to an object with top level environment names ({ production: { ENV_VAR_NAME: value, ... } }).

Terminal

./node_modules/.bin/env-cmd -f ./async-file.js -- node index.js

-x expands vars in arguments

EnvCmd supports expanding $var values passed in as arguments to the command. The allows a user to provide arguments to a command that are based on environment variable values at runtime.

NOTE: You must escape the $ character with \ or your terminal might try to auto expand it before passing it to env-cmd.

Terminal

# $VAR will be expanded into the env value it contains at runtime
./node_modules/.bin/env-cmd -x -- node index.js --arg=\$VAR

or in package.json (use \\ to insert a literal backslash)

{
  "script": {
    "start": "env-cmd -x -- node index.js --arg=\\$VAR"
  }
}

--silent suppresses env-cmd errors

EnvCmd supports the --silent flag the suppresses all errors generated by env-cmd while leaving errors generated by the child process and cli signals still usable. This flag is primarily used to allow env-cmd to run in environments where the .env file might not be present, but still execute the child process without failing due to a missing file.

💿 Examples

You can find examples of how to use the various options above by visiting the examples repo env-cmd-examples.

💽️ Environment File Formats

These are the currently accepted environment file formats. If any other formats are desired please create an issue.

• .env as key=value
• .env.json Key/value pairs as JSON
• .env.js JavaScript file exporting an object or a Promise that resolves to an object
• .env-cmdrc as valid json or .env-cmdrc.json in execution directory with at least one environment { "dev": { "key1": "val1" } }
• .env-cmdrc.js JavaScript file exporting an object or a Promise that resolves to an object that contains at least one environment

🗂 Path Rules

This lib attempts to follow standard bash path rules. The rules are as followed:

Home Directory = /Users/test

Working Directory = /Users/test/Development/app

Type	Input Path	Expanded Path
Absolute	/some/absolute/path.env	/some/absolute/path.env
Home Directory with ~	~/starts/on/homedir/path.env	/Users/test/starts/on/homedir/path.env
Relative	./some/relative/path.env or some/relative/path.env	/Users/test/Development/app/some/relative/path.env
Relative with parent dir	../some/relative/path.env	/Users/test/Development/some/relative/path.env

🛠 API Usage

EnvCmd

A function that executes a given command in a new child process with the given environment and options

• options { object }
  • command { string }: The command to execute (node, mocha, ...)
  • commandArgs { string[] }: List of arguments to pass to the command (['-R', 'Spec'])
  • envFile { object }
    • filePath { string }: Custom path to .env file to read from (defaults to: ./.env)
    • fallback { boolean }: Should fall back to default ./.env file if custom path does not exist
  • rc { object }
    • environments { string[] }: List of environment to read from the .rc file
    • filePath { string }: Custom path to the .rc file (defaults to: ./.env-cmdrc(|.js|.json))
  • options { object }
    • expandEnvs { boolean }: Expand $var values passed to commandArgs (default: false)
    • noOverride { boolean }: Prevent .env file vars from overriding existing process.env vars (default: false)
    • silent { boolean }: Ignore any errors thrown by env-cmd, used to ignore missing file errors (default: false)
    • useShell { boolean }: Runs command inside a new shell instance (default: false)
    • verbose { boolean }: Prints extra debug logs to console.info (default: false)
  • Returns { Promise<object> }: key is env var name and value is the env var value

GetEnvVars

A function that parses environment variables from a .env or a .rc file

• options { object }
  • envFile { object }
    • filePath { string }: Custom path to .env file to read from (defaults to: ./.env)
    • fallback { boolean }: Should fall back to default ./.env file if custom path does not exist
  • rc { object }
    • environments { string[] }: List of environment to read from the .rc file
    • filePath { string }: Custom path to the .rc file (defaults to: ./.env-cmdrc(|.js|.json))
  • verbose { boolean }: Prints extra debug logs to console.info (default: false)
• Returns { Promise<object> }: key is env var name and value is the env var value

🧙 Why

Because sometimes it is just too cumbersome passing a lot of environment variables to scripts. It is usually just easier to have a file with all the vars in them, especially for development and testing.

🚨Do not commit sensitive environment data to a public git repo! 🚨

🧬 Related Projects

cross-env - Cross platform setting of environment scripts

📋 Contributing Guide

I welcome all pull requests. Please make sure you add appropriate test cases for any features added. Before opening a PR please make sure to run the following scripts:

• npm run lint checks for code errors and format according to ts-standard
• npm test make sure all tests pass
• npm run test-cover make sure the coverage has not decreased from current master

Changelog

11.0.0

• BREAKING: Drop support for nodejs v8 to v20.9. The minimum supported nodejs version is now v20.10.
• BREAKING: Removed -r flag and use only -f flag.
• BREAKING: Support inline comments in .env files. A # character now signifies the start of an inline comment, unless the value is surrounded by quotation marks (").
• BREAKING: Migrated the repository to ESM modules instead of CommonJS.
• BREAKING: Support variable expansion using curly-brace syntax (${MY_VAR}), when the -x option is enabled.
• Feature: Support loading env variables from .cjs and .mjs files.
• Feature: Support loading env variables from .ts, .cts, and .mts files.
• Feature: When loading an invalid JSON file, show the original parse error.
• Feature: Add a more helpful error message when trying to invoke env-cmd as a standalone command.
• Feature: Added support for nested env variables within env files with the --recursive flag
• Docs: clarify how variable expansion works.
• Internal: Replaced Travis CI with GitHub Actions, run unit tests on windows.
• Internal: Configure automatic releases to npm from GitHub Actions
• Internal: Refactor the loader logic, to make it easier to add other loaders.
• Upgrade: Update all dependencies.
• Upgrade: Upgraded all devDependencies