Testing for the presence of input from stdin.

[Fredrik Lundh]

Will McDonald wrote:

> > There are more experienced UNIXers here, but from my POV I don't see how
> > that can happen. The reason is simply that
> >
> >  - sys.stdin alwasy exists (unless you close it yourself)
> >
> >  - in a pipe (which this essentially is) there is now way to know if there
> > is more date to come or not, except for the "broken pipe" error - but that
> > won't happen to you, as sys.stdin is not broken just because there is
> > currently no data arriving.
>
> That's a good point. I did wonder if it'd just have to sit there
> waiting for input much like cat would. I think that's preferable, and
> simpler :), than implementing timeouts.

the usual way to implement this is to treat the filename "-" as stdin.

    if filename == "-":
        f = sys.stdin
    else:
        f = open(filename)

    ... read from f ...

    if f is not sys.stdin:
        f.close()

</F>