hello from child - hello from child - hello from child - main process exiting hello from child - hello from child - hello from child - hello from child - hello from child - hello from child - notice that the copies print their output in random orderand the parent program exits before all children doall of these programs are really running in parallel on windows also observe that the child program' output shows up in the console box where spawnv py was runwhen using p_nowaitstandard output comes to the parent' consolebut it seems to go nowhere when using p_detach (which is most likely feature when spawning gui programsbut having shown you this calli need to again point out that both the subprocess and multiprocessing modules offer more portable alternatives for spawning programs with command lines today in factunless os spawn calls provide unique behavior you can' live without ( control of shell window pop ups on windows)the platform-specific alternatives code of example - can be replaced altogether with the portable multi processing code in example - the os startfile call on windows although os spawn calls may be largely superfluous todaythere are other tools that can still make strong case for themselves for instancethe os system call can be used on windows to launch dos start commandwhich opens ( runsa file independently based on its windows filename associationsas though it were clicked os startfile makes this even simpler in recent python releasesand it can avoid blocking its callerunlike some other tools using the dos start command to understand whyfirst you need to know how the dos start command works in general roughlya dos command line of the form start command works as if command were typed in the windows run dialog box available in the start button menu if command is filenameit is opened exactly as if its name was double-clicked in the windows explorer file selector gui for instancethe following three dos commands automatically start internet explorermy registered image viewer programand my sound media player program on the files named in the commands windows simply opens the file with whatever program is associated to handle filenames of that form moreoverall three of these programs run independently of the dos console box where the command is typedother ways to start programs