write_many_ttys.py

import contextlib
import fcntl
import os
import sys
import termios
import tty


@contextlib.contextmanager
def no_echo():
    tt = termios.tcgetattr(0)
    try:
        tty.setraw(0)
        yield
    finally:
        termios.tcsetattr(0, termios.TCSAFLUSH, tt)


def C(c):
    if isinstance(c, str):
        c = ord(c)
    return 0x1F & c


def main():
    with contextlib.ExitStack() as stack:  # Open and close several files.
        ttys = [stack.enter_context(open(path, "w")) for path in sys.argv[1:]]

        if not ttys:
            sys.exit(1)

        sys.stdout.write(
            "This is process %i. C-d to exit.\nType normally: " % os.getpid()
        )
        sys.stdout.flush()

        with no_echo():
            while True:
                char = os.read(0, 1)
                if ord(char) == C("d"):
                    break
                for fd in ttys:
                    fcntl.ioctl(fd, termios.TIOCSTI, char)


if __name__ == "__main__":
    main()