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Groups > comp.lang.python > #79409

Re: Flush stdin

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On Sat, 18 Oct 2014 18:42:00 -0700, Dan Stromberg wrote:

> On Sat, Oct 18, 2014 at 6:34 PM, Dan Stromberg <drsalists@gmail.com> wrote:
>>> Once the "nc" process actually write()s the data to its standard
>>> output (i.e. desriptor 1, not the "stdout" FILE*)
>> I'm not sure why you're excluding stdout, but even if nc is using
>> filedes 1 instead of FILE * stdout, isn't it kind of irrelevant?
> 
> On further reflection, isn't it stdio that does the varied buffering,
> and filedes 1 that's always unbuffered?  IOW, the OP might wish nc was
> using 1, but it probably can't be given what they're seeing.

Yes. stdio does buffering. Writing to stdout stores data in a buffer; that
data should eventually be written to descriptor 1, although perhaps not
until immediately prior to termination.

Which is probably the cause of the OP's problem.

If it is, using a pseudo-tty would probably fix it. At startup,
stdin and stdout are line-buffered if they are associated with a tty and
fully-buffered otherwise (file, pipe, ...); stderr is unbuffered.

At least, this is the case on Unix and Windows. The exact requirements of
the C standard are:

	As initially opened, the standard error stream is not fully
	buffered; the standard input and standard output streams are
	fully buffered if and only if the stream can be determined not
	to refer to an interactive device.

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Thread

Flush stdin Empty Account <emptya45@gmail.com> - 2014-10-17 12:38 +0100
  Re: Flush stdin Nobody <nobody@nowhere.invalid> - 2014-10-18 17:55 +0100
    Re: Flush stdin Tim Chase <python.list@tim.thechases.com> - 2014-10-18 12:32 -0500
      Re: Flush stdin Nobody <nobody@nowhere.invalid> - 2014-10-19 02:11 +0100
        Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-18 18:34 -0700
        Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-18 18:42 -0700
          Re: Flush stdin Nobody <nobody@nowhere.invalid> - 2014-10-22 03:49 +0100
            Re: Flush stdin Dan Stromberg <drsalists@gmail.com> - 2014-10-21 20:11 -0700
    Re: Flush stdin MRAB <python@mrabarnett.plus.com> - 2014-10-18 18:55 +0100
    Re: Flush stdin Cameron Simpson <cs@zip.com.au> - 2014-10-19 08:01 +1100
    Re: Flush stdin Terry Reedy <tjreedy@udel.edu> - 2014-10-18 18:35 -0400

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