Support stdout file redirects in session.run()

[schuderer]

How would this feature be useful?
When building projects, I find myself having to use commands which generate output to stdout (such as pipenv lock -r) which I want to redirect to a file (e.g. >docs/requirements.txt). This currently is not possible with session.run(), because, as I understand it, special characters such as > are being escaped before they are run.

Describe the solution you'd like
It would be handy if session.run() would accept something like session.run("echo", "hello", ">hello.txt") or session.run("echo", "hello", ">", "hello.txt") and pass the redirect through so it gets executed when running the command.

Describe alternatives you've considered
I am using Makefiles and, for cross-platform reasons, make.bat. I also played around with task-specific shell/batch files. Having nox at hand, I am hoping I can centralize all my test-, but also more general build-related processes into one neat and tidy script, replacing non-Windows-compatible Makefiles and reducing clutter.

[theacodes]

Hi, we added this in #180. You can do

with open("pipenv-log.txt", "w") as out:
    session.run("pipenv", "lock", "-r", stdout=out)

[henryiii]

Maybe dumb question: is there a way to get the output directly in a variable, without a file? I don't seem to be get a StringIO/BytesIO to work here, or a redirect_stdout. I get io.UnsupportedOperation: fileno.

[henryiii]

Also, I don't think this was ever documented?

[henryiii]

Ahh, output is returned if this is silent. I thought I'd done this somewhere before. (Ironically, probably for something very similar to what I'm doing now, grabbing a version).