Using rich to write to (linux) virtual consoles

[jakane]

I would like to use rich to provide a "monitoring" screen on a virtual console that does not have a login process running. Think Raspberry Pi with head, hit ALT-F7 to go to /dev/vcs7 | dev/tty7. I can then run an application that talks to the attached monitor without having to have someone logged in.

I can use openvt(1) to start a program on a specific VT, ala

openvt --console=7 -- python -m rich.progress

That will run the demo on the virtual console just fine.

I was hoping that I could bypass using openvt and do something directly, inside the rich.console.Console() constructor.

I have tried:

from rich.console import Console
console = Console(force_terminal=True, force_interactive=True, file="/dev/tty4")
console.print("Hello World!")

What I get is the following error:

/home/jkane/venv/lib/python3.7/site-packages/rich/console.py in print(self, sep, end, style, justify, overflow, no_wrap, emoji, markup, highlight, width, height, crop, soft_wrap, new_line_start, *objects)
   1653                     buffer_extend(line)
   1654             else:
-> 1655                 self._buffer.extend(new_segments)
   1656 
   1657     def print_json(

/home/jkane/venv/lib/python3.7/site-packages/rich/console.py in __exit__(self, exc_type, exc_value, traceback)
    852     def __exit__(self, exc_type: Any, exc_value: Any, traceback: Any) -> None:
    853         """Exit buffer context."""
--> 854         self._exit_buffer()
    855 
    856     def begin_capture(self) -> None:

/home/jkane/venv/lib/python3.7/site-packages/rich/console.py in _exit_buffer(self)
    810         """Leave buffer context, and render content if required."""
    811         self._buffer_index -= 1
--> 812         self._check_buffer()
    813 
    814     def set_live(self, live: "Live") -> None:

/home/jkane/venv/lib/python3.7/site-packages/rich/console.py in _check_buffer(self)
   1975                         text = self._render_buffer(self._buffer[:])
   1976                         try:
-> 1977                             self.file.write(text)
   1978                         except UnicodeEncodeError as error:
   1979                             error.reason = f"{error.reason}\n*** You may need to add PYTHONIOENCODING=utf-8 to your environment ***"

AttributeError: 'str' object has no attribute 'write'

the environment is correctly set:

In [9]: console._environ["PYTHONIOENCODING"]
Out[9]: 'utf-8'

If I call the constructor without a file= the code works as expected.

[willmcgugan]

The file argument accepts a file, not a path.

[jakane]

Thanks for the pointer ... I had to do a little bit of digging, but I found the following pattern appears to work:

import io
import os
from rich.console import Console

tty = io.TextIOWrapper(io.FileIO(os.open("/dev/tty7", os.O_NOCTTY | os.O_RDWR), "r+"))
console = Console(file=tty, force_terminal=True, force_interactive=True)
console.print("Hello World! This [red]really[/] [green]did[/] work this time")