function environment() {
	const cache = new Map();

	/**
	 * Checks if a path is a child of a directory.
	 * @param {string} parentPath The parent path to check.
	 * @param {string} childPath The path to check.
	 * @returns {boolean} Whether or not the given path is a child of a directory.
	 */
	function isChildOfDirectory(parentPath, childPath) {
		return !path.relative(parentPath, childPath).startsWith("..");
	}

	/**
	 * Synchronously executes a shell command and formats the result.
	 * @param {string} cmd The command to execute.
	 * @param {Array} args The arguments to be executed with the command.
	 * @throws {Error} As may be collected by `cross-spawn.sync`.
	 * @returns {string} The version returned by the command.
	 */
	function execCommand(cmd, args) {
		const key = [cmd, ...args].join(" ");

		if (cache.has(key)) {
			return cache.get(key);
		}

		const process = spawn.sync(cmd, args, { encoding: "utf8" });

		if (process.error) {
			throw process.error;
		}

		const result = process.stdout.trim();

		cache.set(key, result);
		return result;
	}

	/**
	 * Normalizes a version number.
	 * @param {string} versionStr The string to normalize.
	 * @returns {string} The normalized version number.
	 */
	function normalizeVersionStr(versionStr) {
		return versionStr.startsWith("v") ? versionStr : `v${versionStr}`;
	}

	/**
	 * Gets bin version.
	 * @param {string} bin The bin to check.
	 * @throws {Error} As may be collected by `cross-spawn.sync`.
	 * @returns {string} The normalized version returned by the command.
	 */
	function getBinVersion(bin) {
		const binArgs = ["--version"];

		try {
			return normalizeVersionStr(execCommand(bin, binArgs));
		} catch (e) {
			log.error(
				`Error finding ${bin} version running the command \`${bin} ${binArgs.join(" ")}\``,
			);
			throw e;
		}
	}

	/**
	 * Gets installed npm package version.
	 * @param {string} pkg The package to check.
	 * @param {boolean} global Whether to check globally or not.
	 * @throws {Error} As may be collected by `cross-spawn.sync`.
	 * @returns {string} The normalized version returned by the command.
	 */
	function getNpmPackageVersion(pkg, { global = false } = {}) {
		const npmBinArgs = ["bin", "-g"];
		const npmLsArgs = ["ls", "--depth=0", "--json", pkg];

		if (global) {
			npmLsArgs.push("-g");
		}

		try {
			const parsedStdout = JSON.parse(execCommand("npm", npmLsArgs));

			/*
			 * Checking globally returns an empty JSON object, while local checks
			 * include the name and version of the local project.
			 */
			if (
				Object.keys(parsedStdout).length === 0 ||
				!(parsedStdout.dependencies && parsedStdout.dependencies.eslint)
			) {
				return "Not found";
			}

			const [, processBinPath] = process.argv;
			let npmBinPath;

			try {
				npmBinPath = execCommand("npm", npmBinArgs);
			} catch (e) {
				log.error(
					`Error finding npm binary path when running command \`npm ${npmBinArgs.join(" ")}\``,
				);
				throw e;
			}

			const isGlobal = isChildOfDirectory(npmBinPath, processBinPath);
			let pkgVersion = parsedStdout.dependencies.eslint.version;

			if ((global && isGlobal) || (!global && !isGlobal)) {
				pkgVersion += " (Currently used)";
			}

			return normalizeVersionStr(pkgVersion);
		} catch (e) {
			log.error(
				`Error finding ${pkg} version running the command \`npm ${npmLsArgs.join(" ")}\``,
			);
			throw e;
		}
	}

	return [
		"Environment Info:",
		"",
		`Node version: ${getBinVersion("node")}`,
		`npm version: ${getBinVersion("npm")}`,
		`Local ESLint version: ${getNpmPackageVersion("eslint", { global: false })}`,
		`Global ESLint version: ${getNpmPackageVersion("eslint", { global: true })}`,
		`Operating System: ${os.platform()} ${os.release()}`,
	].join("\n");
}
Generates and returns execution environment information.
@returns {string} A string that contains execution environment information.