问题：
What is the best way to open a file as read/write if it exists, or if it does not, then create it and open it as read/write? 如果文件以读/写方式打开，或者以不存在的方式创建，然后以读/写方式打开，最好的方法是什么？ From what I read, file = open('myfile.dat', 'rw') should do this, right? 根据我的阅读， file = open('myfile.dat', 'rw')应该这样做，对吗？
It is not working for me (Python 2.6.2) and I'm wondering if it is a version problem, or not supposed to work like that or what. 它对我不起作用（Python 2.6.2），我想知道这是否是版本问题，或者不应该那样工作或做什么。
The bottom line is, I just need a solution for the problem. 最重要的是，我只需要解决这个问题。 I am curious about the other stuff, but all I need is a nice way to do the opening part. 我对其他东西很好奇，但是我所需要的只是做开始部分的好方法。
The enclosing directory was writeable by user and group, not other (I'm on a Linux system... so permissions 775 in other words), and the exact error was: 封闭目录可由用户和组而非其他用户（我在Linux系统上...因此权限775）可写，确切的错误是：
IOError: no such file or directory. IOError：没有这样的文件或目录。
解决方案：
参考一： https://stackoom.com/question/CRty/如果不存在-则Python中的open-不会创建文件参考二： https://oldbug.net/q/CRty/open-in-Python-does-not-create-a-file-if-it-doesn-t-exist
来源：oschina
链接：https://my.oschina.net/u/3797416/blog/4275227