Hi, I spent some time googleing for "OSError 4" before it occurred to me that "4" was actually an irrelevant implementation detail. As soon as I searched for "EINTR", I found exactly what I was looking for. (not really but this is another story) I jumped to the conclusion that OSError.__str__() should return the symbolic error number instead of the integer value. I was about to write a patch but I just noticed that OSError and friends are implemented in C so I guess it will be a bit harder than expected. The error message comes from EnvironmentError.__str__() which is implemented by EnvironmentError_str() in Objects/exceptions.c. A Python implementation could have replaced self.errno in the format string args by errno.errorcode[self.errno]. However, it's not clear to me if there is such a mapping available in C. Since my fix is not as trivial as I expected, I ask for advice regarding the following questions: 1) Should OSError.__str__() print the symbolic name of errno? 2) Where can I find the symbolic name in C? Best regards, -- Yannick Gingras