[Tutor] how to get variable from an external script or program

[shawn bright]

Hey all

I have a small program that when run from the command line, will
return a certain value for an arguement. Like this:

> mfetchz 45
> 45j

so the program is mfetchz and the argument is 45

i know i can call the program with os.system("mfetchz 45")
but how do i get the return?

The OS is linux, if that matters

thanks

sk