为什么“exec()”不是在脚本中工作,而是以交互方式工作?

我在一个凭证文件中读取一个字符串,然后运行 exec() 在该字符串上,使各种凭据作为变量可用。凭据文件包含以下文本:

customer_number = "9999999999"
PIN             = "9999999999"
passcode        = "9999999999"
account_code    = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"

这在交互式Python中有效(变量可用),但在脚本中失败。为什么会这样?我怎样才能让它工作?

with open(filepath_credentials, "r") as file_credentials:
    credentials = file_credentials.read()
    exec(credentials)
print(customer_number)