Automate Your .env.example Generation - A Developer's Time-Saver

TL;DR - Quick Fix
Run this in your terminal:

sed 's/=.*/=/' .env.local > .env.example

The Problem

As developers, we often struggle with maintaining .env.example files in our repositories. The common workflow goes like this:

1. Create a .env.local with actual values
2. Manually copy it to .env.example
3. Remove all sensitive values
4. Forget to update .env.example when adding new variables
5. Repeat this process every time

This manual process is:

• Time-consuming
• Error-prone
• Easy to forget
• Often leads to outdated example files

The Solution

Add this one-liner to your package.json scripts:

{
  "scripts": {
    "env:gen": "sed 's/=.*/=/' .env.local > .env.example"
  }
}

Now you can generate your .env.example file with a single command:

npm run env:gen
# or
yarn env:gen
# or
pnpm env:gen

How It Works

Let's break down the command:

1. sed 's/=.*/=/': Uses sed to replace everything after = with nothing
2. .env.local: Reads from your actual env file
3. > .env.example: Outputs to the example file

For example, this:

DATABASE_URL=postgresql://user:password@localhost:5432/mydb
API_KEY=1234567890
DEBUG=true

Becomes:

DATABASE_URL=
API_KEY=
DEBUG=

Best Practices

1. Add to Your Development Workflow:

   # After adding new env variables
   npm run env:gen
   git add .env.example
   git commit -m "chore: update env example"

2. Git Hooks: Consider adding this to your pre-commit hook to never forget updating the example file.

3. Documentation: Add comments in your .env.local file - they'll be preserved in the example:

   # Database configuration
   DATABASE_URL=your-value-here
    
   # API credentials
   API_KEY=your-key-here

When to Use This

This command is particularly useful when:

• Starting a new project
• Adding new environment variables
• Sharing your project with other developers
• Maintaining open-source projects
• Ensuring your example stays in sync with actual requirements

Pro Tips

1. Custom Variations:

   {
     "scripts": {
       "env:gen": "sed 's/=.*/=/' .env.local > .env.example",
       "env:gen:dev": "sed 's/=.*/=/' .env.development > .env.development.example",
       "env:gen:all": "npm run env:gen && npm run env:gen:dev"
     }
   }

2. Add Default Values:

   NODE_ENV=development
   DEBUG=false
   PORT=3000

Note: This command works on Unix-based systems (macOS, Linux). For Windows, you might need to use WSL or alternative commands.