One thing I've been thinking of: how about making typed file descriptors?

Besides stdio and stdout, one of the best-accepted conventions on modern operating systems running a graphical shell seems to be the clipboard.

Programs can offer different mime types trough a clipboard, so why not do so trough a pipe or file descriptor? That would bring us a bit closer to powershell, while remaining backwards-compatible.

    cat pipe.dot <- text/plain
    | dot <- text/plain, text/dot, image/svg+xml, application/pdf, application/postscript, etc
    | xclip

Instead of xclip in the above example, one could use an image viewer, a multiplexer a bit like tee (1) but to redirect to standard input, etc. One could force a pipe to filter out some mimetypes, or use a program dedicated to that. One could imagine bidirectional communications over a channel.

    xeyes | ssh somehost
    record-audio.sh | mail someone@somewhere
    nmtui | guitoolkit
    rsync | guitoolkit
    ssh somehost rsync | guitoolkit

Basically, building on the strengths of UNIX.

This is something I've been working on with my shell, https://github.com/lmorg/murex

The problem isn't so much finding a way of passing metadata but how do you retain compatibility with existing GNU / UNIX tools? It would be easy to create an entirely new shell (like Powershell) that throws out backwards compatibility but that wouldn't be very practical on Linux/UNIX when so much of it is powered by old POSIX standards.

I addressed this by having a wrapper around pipes. Anything that connects out to a classic executable is a traditional POSIX byte stream with no type data sent. Anything sent to a command that is written to support my shell can make use of said meta data.

As for handling graphical components, that's a little easier. Many command line programs already alter their behaviour depending on whether STDOUT is a TTY or not. I take things a little further and have a media handler function, called `open`, that inlines stuff in a shell that can be (it will render images in the terminal) but if STDOUT is a TTY then it will pipe the image data instead.