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Re: Does mkstemp open files only if they don't already exist?

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On Wed, Sep 2, 2015 at 12:45 AM, Steven D'Aprano <steve@pearwood.info> wrote:
> I assume the answer is "Yes", but is it safe to expect that
> tempfile.mkstemp() will only create a file that doesn't already exist? I
> presume that there's no chance of it over-writing an existing file (say,
> due to a race-condition).

It depends on OS support, but with that, yes, it is guaranteed to be
safe; the file is opened with an exclusivity flag. Check your system's
man pages for details, or here:

http://linux.die.net/man/3/open

O_EXCL|O_CREATE makes an "atomic file creation" operation which will
fail if another process is doing the same thing. I'm not sure how
mkstemp() handles that failure, but my guess/expectation is that it
would pick a different file name and try again.

ChrisA

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Thread

Does mkstemp open files only if they don't already exist? Steven D'Aprano <steve@pearwood.info> - 2015-09-02 00:45 +1000
  Re: Does mkstemp open files only if they don't already exist? Chris Angelico <rosuav@gmail.com> - 2015-09-02 00:57 +1000
  Re: Does mkstemp open files only if they don't already exist? Laura Creighton <lac@openend.se> - 2015-09-01 19:09 +0200

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