Function fileExists

lib/install.js:95–102

	}

	let fileExists = f => {
		try {
			fs.accessSync(f);
			return true;
		} catch (e) {
			Error.throwIfNot(Error.ENOENT, e);
		}
	};

	const shell = process.env['SHELL'];
	const shellName = shell && path.basename(shell);