将终端命令中的文本打印到shell中

I am creating a MS-DOS replica to test out my python skills since I am particularly new and I'm writing the "dir" command. Right now, the command opens a terminal that seems to be doing what I want it to be doing, except for printing it out into a terminal instead of the program output. I want to transfer the text it creates in the command line to the output of the program, basically. Here's what I'm using right now:I am creating a MS-DOS replica to test out my p