Can all paths in a Python program use \"..\" (for the parent directory) and / (for separating path components), and still work whatever the platform?
On one
Within python, using /
will always work. You will need to be aware of the OS convention if you want to execute a command in a subshell
myprog = "/path/to/my/program"
os.system([myprog, "-n"]) # 1
os.system([myprog, "C:/input/file/to/myprog"]) # 2
Command #1 will probably work as expected.
Command #2 might not work if myprog
is a Windows command and expects to parse its command line arguments to get a Windows file name.