[issue13601] sys.stderr should be line-buffered when stderr is not a TTY

[Torsten Landschoff]

Torsten Landschoff <t.landschoff at gmx.net> added the comment:

> Looking at http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html (which also covers stdout and stderr), it specifically says about stderr: "When opened, the standard error stream is not fully buffered;".

I was of the impression that this is defined in ISO C already. Unfortunately, I only have ISO C 99 at hand, but this clearly states in section 7.19.3 (Files), enumeration item 7:

> 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.

I am quite sure this is just as as it was in the original ANSI C standard.

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nosy: +torsten

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