Mini Shell

# A program which exits after starting a child which inherits its
# stdin/stdout/stderr and keeps them open until stdin is closed.

import os
import sys


def grandchild():
    sys.stdout.write("grandchild started")
    sys.stdout.flush()
    sys.stdin.read()


def main():
    if sys.argv[1] == "child":
        if sys.argv[2] == "windows":
            import win32api as api  # type: ignore[import]
            import win32process as proc  # type: ignore[import]

            info = proc.STARTUPINFO()
            info.hStdInput = api.GetStdHandle(api.STD_INPUT_HANDLE)
            info.hStdOutput = api.GetStdHandle(api.STD_OUTPUT_HANDLE)
            info.hStdError = api.GetStdHandle(api.STD_ERROR_HANDLE)
            python = sys.executable
            scriptDir = os.path.dirname(__file__)
            scriptName = os.path.basename(__file__)
            proc.CreateProcess(
                None,
                " ".join((python, scriptName, "grandchild")),
                None,
                None,
                1,
                0,
                os.environ,
                scriptDir,
                info,
            )
        else:
            if os.fork() == 0:
                grandchild()
    else:
        grandchild()


if __name__ == "__main__":
    main()