How to run a dos executable from python

[lblr33]

I have an executable (e.g. myprog.exe) which takes some set number of
arguments.

This command works ok:
os.system(r"c:\tmp\myprog.exe arg1 arg2 arg3")

The problem is that the path to the program and the arguments are
variable at runtime so I need to pass them as arguments.

Thanks