code: function resolveEnvVars(varValue) {
    const envUnixRegex = /(\\*)(\$(\w+)|\${(\w+)})/g // $my_var or ${my_var} or \$my_var
    return varValue.replace(
      envUnixRegex,
      (_, escapeChars, varNameWithDollarSign, varName, altVarName) => {
        // do not replace things preceded by a odd number of \
        if (escapeChars.length % 2 === 1) {
          return varNameWithDollarSign
        }
        return (
          escapeChars.substr(0, escapeChars.length / 2) +
          (process.env[varName || altVarName] || '')
        )
      },
    )
  }
docs: This will attempt to resolve the value of any env variables that are inside
  this string. For example, it will transform this:
  cross-env FOO=$NODE_ENV BAR=\\$NODE_ENV echo $FOO $BAR
  Into this:
  FOO=development BAR=$NODE_ENV echo $FOO
  (Or whatever value the variable NODE_ENV has)
  Note that this function is only called with the right-side portion of the
  env var assignment, so in that example, this function would transform
  the string "$NODE_ENV" into "development"
  @param {String} varValue Original value of the env variable
  @returns {String} Converted value