function getFileEnv (env) {
  const validKeys = Object.keys(env).filter(key => validKeyRE.test(key))
  return validKeys.reduce((acc, key) => {
    acc[ key ] = env[ key ]
    return acc
  }, {})
}
Filter out keys that cannot be used in JS
as process.env.[key]
Examples: ProgramFiles(x86), BASH_FUNC_which%%