npm package: @substrate-system/env-cmd
Description: Executes a command using the environment variables in an env file
Author: Todd Bluhm
Latest version: 10.1.0

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# env-cmd

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

## contents
<!-- toc -->

## fork
This is a fork of [toddbluhm/env-cmd](https://github.com/toddbluhm/env-cmd).

## 💾 Install

```sh
npm i -D @substrate-system/env-cmd
```

## Example

### Basic Usage

#### `.env` file

```sh
# .env
# This is a comment
ENV1=THANKS
ENV2=FOR ALL
ENV3=THE FISH
```

#### `package.json`

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

#### terminal

```sh
npx env-cmd -- node index.js
```

### Use a custom env file path
To use a custom env filename or path, pass the `-f` flag.

#### terminal

```sh
npx env-cmd -f ./custom/path/.env -- node index.js
```

## Help

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

Options:
  -v, --version                       output the version number
  -e, --environments [env1,env2,...]  The rc file environment(s) to use
  -f, --file [path]                   Custom env file path (default path: ./.env)
  --fallback                          Fallback to default env file path, if custom env file path not found
  --no-override                       Do not override existing environment variables
  -r, --rc-file [path]                Custom rc file path (default path: ./.env-cmdrc(|.js|.json)
  --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
  -x, --expand-envs                   Replace $var in args and command with environment variables
  -h, --help                          output usage information
```

## 🔬 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`**

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

**Terminal**

```sh
./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**

```sh
./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**
   
   ```sh
   ./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**

```sh
# $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)
```json
{
  "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](https://github.com/toddbluhm/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`](https://github.com/kentcdodds/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](https://github.com/toddbluhm/ts-standard)
- `npm test` make sure all tests pass
- `npm run test-cover` make sure the coverage has not decreased from current master