how to calculate the size of sys.stdin?
Michael Hudson
mwh21 at cam.ac.uk
Thu Apr 12 04:19:55 EDT 2001
grante at visi.com (Grant Edwards) writes:
> In article <mailman.987030856.375.python-list at python.org>, Robin Thomas wrote:
>
> >sys.stdin is more like a pipe, and not a regular file. You
> >can't ask a pipe how many bytes it contains before you read
> >from it.
>
> Actually, you can.
>
> At least on some Unix systems, the FIONREAD ioctl() call will
> tell you how many bytes there are in a pipe waiting to be read.
> IIRC, it also works on some tty devices as well. Probably not
> very portable, and somebody could have shoved more bytes into
> the other end after the ioctl() and before the read(), so you
> could get more that you expect, but you shouldn't get less.
That's interesting for a pet project of mine. How on earth does one
go about learning things like that? Is this sort of stuff in Stevens'
APUE?
Cheers,
M.
--
We did requirements and task analysis, iterative design, and user
testing. You'd almost think programming languages were an interface
between people and computers. -- Steven Pemberton
(one of the designers of Python's direct ancestor ABC)
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