[issue20057] wrong behavior with fork and mmap

[Brett Tiplitz]

Brett Tiplitz added the comment:

Man page currently says as follows: (this does not says it's deprecated or that files have to be closed on exec)...  So I'd think some more comments would help. And as mentioned, which a user can close his own fd's, the mmap call creates a special problem since the user can't work around the issue cleanly though fixed in the subprocess calls.


s.system(command)

    Execute the command (a string) in a subshell. This is implemented by calling the Standard C function system(), and has the same limitations. Changes to sys.stdin, etc. are not reflected in the environment of the executed command.

    On Unix, the return value is the exit status of the process encoded in the format specified for wait(). Note that POSIX does not specify the meaning of the return value of the C system() function, so the return value of the Python function is system-dependent.

    On Windows, the return value is that returned by the system shell after running command, given by the Windows environment variable COMSPEC: on command.com systems (Windows 95, 98 and ME) this is always 0; on cmd.exe systems (Windows NT, 2000 and XP) this is the exit status of the command run; on systems using a non-native shell, consult your shell documentation.

    The subprocess module provides more powerful facilities for spawning new processes and retrieving their results; using that module is preferable to using this function. See the Replacing Older Functions with the subprocess Module section in the subprocess documentation for some helpful recipes.

    Availability: Unix, Windows.

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<http://bugs.python.org/issue20057>
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