Subprocess confusion: how file-like must stdin be?

[Fredrik Lundh]

Cameron Laird wrote:

> Your interactive session does indeed exhibit the behavior that
> puzzles me.  My expectation was that StringIO and the std* 
> parameters to Popen() were made for each other; certainly there
> are many cases where stdout and stderr can be redirected *to* a
> StringIO.  Is it simply the case that stdin demands a more
> file-like object?  While that disappoints me, I certainly can
> program around it.  My question, then:  does stdin effectively
> require something really in the filesystem, or perhaps the
> stdout of a previous subprocess?  Is there no built-in way to
> feed it an in-memory construct?

set the appropriate stream to subprocess.PIPE, and write to it.

    p = subprocess.Popen(..., stdin=subprocess.PIPE)
    p.stdin.write("hello")
    p.stdin.close() # signal end of file

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