How to use subprocess to run a program without a window showing?

Question

I am using subprocess.call() to programatically launch a software on my PC (the Meta Trader platform for forex trading, to be exact). The call works fine, the terminal is launched properly, however I now want to improve the experience by removing the popping up Meta Trader window. I know that in web scraping it is possible to use a headless browser, enabling that scraping be done without an actual(ly visible) web browser window showing on the screen. I was wondering if there is some way to achieve the same functionality using subprocess.call() (or else).

Answer 1

There doesn't seem to be built-in support on other platforms, but it's possible on Windows by passing a STARTUPINFO instance to the Popen constructor.

The following example starts the Notepad editor in the background. Its window is hidden, but the program is running as the Task Manager would show. Pressing Ctrl+C stops the program and terminates the background process.

import subprocess
from time import sleep

process = subprocess.Popen(
    'notepad',
    startupinfo=subprocess.STARTUPINFO(
        dwFlags=subprocess.STARTF_USESHOWWINDOW,
        wShowWindow=subprocess.SW_HIDE,
    ),
)

try:
    while process.poll() is None:
        sleep(1)
except KeyboardInterrupt:
    process.kill()

Note that this may not work for more complex applications that start their own subprocesses, such as the Chrome browser to name but one example. One may then have to go through the Windows API in order to hide the application windows after they were created.