views:

629

answers:

4

I want to open a process in the background and interact with it, but this process should be invisible in both Linux and Windows. In Windows you have to do some stuff with STARTUPINFO, while this isn't valid in Linux:

ValueError: startupinfo is only supported on Windows platforms

Is there a simpler way than creating a separate Popen command for each OS?

if os.name == 'nt':
    startupinfo = subprocess.STARTUPINFO()
    startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
    proc = subprocess.Popen(command, startupinfo=startupinfo)
if os.name == 'posix':
    proc = subprocess.Popen(command)
A: 

I'm not sure you can get much simpler than what you've done. You're talking about optimising out maybe 5 lines of code. For the money I would just get on with my project and accept this as a consquence of cross-platform development. If you do it a lot then create a specialised class or function to encapsulate the logic and import it.

SpliFF
A: 

You can turn your code into:

params = dict()

if os.name == 'nt':
    startupinfo = subprocess.STARTUPINFO()
    startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
    params['startupinfo'] = startupinfo

proc = subprocess.Popen(command, **params)

but that's not much better.

NicDumZ
no need for creating params as on all systems Popen accepts param startupinfo but on posix it should be None
Anurag Uniyal
+6  A: 

you can reduce one line :)

startupinfo = None
if os.name == 'nt':
    startupinfo = subprocess.STARTUPINFO()
    startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
proc = subprocess.Popen(command, startupinfo=startupinfo)
Anurag Uniyal
Aha. I had tried startupinfo = '' and it didn't work. This is the answer I was looking for.
endolith
i just looked thru the subprocess code to see how they generate that error msg and they check if startupinfo is not None, as should be in python
Anurag Uniyal
If you set `STARTF_SHOWWINDOW`, you will also want to initialise the `wShowWindow` member of `startupinfo` to one of the `SW_*` constants. This method relies on the program that you run actually acting upon the `wShowWindow` flag; it's not required to do so.
Greg Hewgill
+1  A: 

Just a note: for Python 2.7 I have to use subprocess._subprocess.STARTF_USESHOWWINDOW instead of subprocess.STARTF_USESHOWWINDOW.

goertzenator