This TypeScript script compares environment variables from .env files with a predefined set, performing set operations (union, intersection, or difference) specified via command-line arguments. It parses the variables, executes the chosen operation, and outputs the results to a file, providing a flexible tool for analyzing and managing environme…

match-env-vars.ts

import { readFileSync, writeFileSync, readdirSync } from "node:fs";
import { join } from "path";

const paste: string = `
  <key>=<value>
  ...
`

const envFiles: string[] = readdirSync(process.cwd()).filter((file) => file.startsWith(".env"));

const parseEnvContent = (content: string): Record<string, string> => {
  const lines = content.split("\n");
  return lines.reduce((acc, line) => {
    const [key, value] = line.split("=").map(part => part.trim());
    if (key && value) {
      acc[key] = value;
    }
    return acc;
  }, {} as Record<string, string>);
};

const pasteEnv: Record<string, string> = parseEnvContent(paste);
const fileEnvs: { fileName: string; vars: Record<string, string> }[] = envFiles.map(file => ({
  fileName: file,
  vars: parseEnvContent(readFileSync(join(process.cwd(), file), "utf-8"))
}));

const operation: string = process.argv[2] || 'intersection';

const performSetOperation = (operation: string): { file: string; key: string; value: string }[] => {
  const result: { file: string; key: string; value: string }[] = [];

  fileEnvs.forEach(({ fileName, vars }): void => {
    Object.entries(vars).forEach(([key, value]): void => {
      const inPaste = pasteEnv[key] === value || Object.values(pasteEnv).includes(value);
      const inFile = true;

      switch (operation) {
        case 'union':
          if (inPaste || inFile) result.push({ file: fileName, key, value });
          break;
        case 'intersection':
          if (inPaste && inFile) result.push({ file: fileName, key, value });
          break;
        case 'difference':
          if (inFile && !inPaste) result.push({ file: fileName, key, value });
          break;
      }
    });
  });
  return result;
};

const matchingPairs: { file: string; key: string; value: string }[] = performSetOperation(operation);

const output: string = matchingPairs.map(({ file, key, value }): string => `${file}: ${key}=${value}`).join("\n");
writeFileSync(join(process.cwd(), `${operation}_env_vars.txt`), output);

console.log(`${operation.charAt(0).toUpperCase() + operation.slice(1)} of environment variables have been written to ${operation}_env_vars.txt`);
console.log("Paste variables processed:", Object.keys(pasteEnv).length);
console.log("File variables processed:", fileEnvs.reduce((sum, { vars }) => sum + Object.keys(vars).length, 0));