Bugs item #1227748, was opened at 2005-06-26 15:37 Message generated for change (Comment added) made by astrand You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1227748&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Python Library Group: Python 2.4 Status: Open Resolution: None Priority: 5 Private: No Submitted By: Andr� Malo (ndparker) Assigned to: Peter Åstrand (astrand) Summary: subprocess: inheritance of std descriptors inconsistent Initial Comment: The inheritance of std descriptors is inconsistent between Unix and Windows implementations. If one calls Popen with stdin = stdout = stderr = None, the caller's std descriptors are inherited on *x, but not on Windows, because of the following optimization (from subprocess.py r1.20): 655 def _get_handles(self, stdin, stdout, stderr): 656 """Construct and return tupel with IO objects: 657 p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite 658 """ 659 if stdin is None and stdout is None and stderr is None: 660 return (None, None, None, None, None, None) 661 I suggest to just remove those lines 659 and 660. The current workaround is to duplicate the handles by the application and supply an own STARTUPINFO structure. ---------------------------------------------------------------------- >Comment By: Peter Åstrand (astrand) Date: 2007-01-29 21:54 Message: Logged In: YES user_id=344921 Originator: NO >If one calls Popen with stdin = stdout = stderr = None, >the caller's std descriptors are inherited on *x, but >not on Windows, This is a correct observation. However, the current implementation is not necessarily wrong. This could instead be seen as a consequence of the different environments. The subprocess documentation states that "With None, no redirection will occur". So, it becomes an interpretation of what this really mean. Since the "default" behaviour on UNIX is to inherit and the default behaviour on Windows is to attach the standard handles to (an often newly created) console window, one could argue that this fits fairly good with the description "no redirection will occur". If we would change this, so that the parents handles are always inherited, then how would you specify that you want to attach the standard handles to the new console window? For best flexibility, the API should allow both cases: Both inherit all handles from the parent as well as attaching all standard handles to the new console window. As you point out, the current API allows this. So why change this? One thing that's clearly an bug is the second part of the documentation: "With None, no redirection will occur; the child's file handles will be inherited from the parent" This is currently only true on UNIX. If we should keep the current behaviour, at least the comment needs to be fixed. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1227748&group_id=5470
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