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envmn — Environment Manager for .env-style Files

envmn is a lightweight command-line utility for managing complex .env files. It helps you lint, format, and switch between environment blocks — like dev and prod — safely and predictably.

Note: envmn currently supports Linux and Windows.

Features

  • Block-based structure — group related variables into labeled sections
  • Switch between environments — move a block (e.g., prod_database) to the bottom to make it active
  • Lint & format — check for malformed lines, duplicates, and inconsistent formatting
  • Pipe-friendly — read from stdin or directly modify files in place
  • Human-readable output — no noise, just clean .env management

Installation

Download the latest binary for your platform from the Releases page.

Linux

mv envmn_linux_x64 envmn
chmod +x envmn
sudo mv envmn /usr/local/bin/

Windows

  1. Download envmn_windows-gnu_x64.exe from the Releases page.
  2. Rename it to envmn.exe (optional, for convenience).
  3. Add its location to your PATH environment variable:
    • Open System Properties → Environment Variables.
    • Under System variables, select Path and click Edit.
    • Add the folder where you placed envmn.exe.
  4. Open a new Command Prompt or PowerShell window and verify:
envmn version

Verify (Linux)

envmn version

Usage

envmn — environment manager for .env-style files

Usage:
  envmn <command> [options] [file]

Commands:
  help                  Show this help message
  version               Display the current version
  list                  List all environment blocks in the file
  lint                  Check for syntax and linting errors
  format                Pretty-format the file
  pick <block>          Reorder the file by moving the specified block down

Input modes:
  - If data is piped in, envmn reads from standard input and writes to standard output.
  - If both a pipe and a file are provided, the piped input takes priority.
  - If no file is provided, envmn assumes a `.env` file exists in the current directory (for convenience).
  - When a file path is provided (or .env is assumed), envmn reads from (and edits, if a file was passed) the file directly.

Example .env File

# Basic API configuration
API_URL=https://api.example.com
API_KEY=123456789abcdef
DEBUG=true

#@ prod_database
DB_HOST=localhost
DB_PORT=5432
DB_USER=admin
DB_PASSWORD=password123
DB_NAME=mydatabase
##

#@ dev_database
DB_HOST=example.com
DB_PORT=5432
DB_USER=admin
DB_PASSWORD=remote1234
DB_NAME=myappproddatabase
##

#@ email_block
MAILGUN_API_KEY=key-xyz123456789
MAILGUN_DOMAIN=mg.example.com
##

Here, each block (between #@ and ##) defines a related set of environment variables. In this case, you have separate configurations for production and development databases.

Switching Environments

Use the pick command to move a specific block (e.g. prod_database) to the bottom of the file. Because variables are parsed in order, the last block overrides earlier ones — effectively switching environments.

envmn pick prod_database .env.example

Before

# ... dev block comes last
#@ prod_database
DB_HOST=localhost
...
##
#@ dev_database
DB_HOST=example.com
...
##

After

# ... prod block moved last (now active)
#@ dev_database
DB_HOST=example.com
...
##
#@ prod_database
DB_HOST=localhost
...
##

Now, all the DB_* variables from prod_database override the ones from dev_database.

Other Commands

Lint

Check for syntax and formatting errors:

envmn lint .env

Format

Reformat and clean up your .env file:

envmn format .env

List

List all block names in the file:

envmn list .env

Help

Display the built-in help:

envmn help

How It Works (Technical Overview)

envmn parses .env files using a small Rust engine that:

  • Detects labeled blocks marked with #@ block_name and closed by ##
  • Normalizes variable lines (trims whitespace, fixes quoting issues)
  • Validates each variable name and key/value format
  • Applies block precedence: variables from later blocks overwrite earlier definitions

The design allows for predictable overrides — switching environments becomes as simple as reordering blocks.

Contributing

Contributions, ideas, and feedback are welcome! Fork the repo, make your changes, and open a PR. N.B. this code might be spaghetti, it's because this is my second Rust project

License

MIT License © 2025 devark28