Variable Scope for Scripts

[snippsat]

The way I've declared file_name and files_to_backup are not in a global way, correct?

That's not correct the are in Global namespace,
so the are global variables in that code,
but they are fine as the are the last step and can not interfere with other stuff.

To take a look,i do this so only new stuff in Global namespace is shown so it don't look so messy.

>>> from pprint import pprint

>>> def read_data_from_file(file_name):
    '''In Local namespace'''
    foo = '/bar'
    bar = 100
    return file_name + foo

# We are in Global namespace so these are global variables
>>> file_name = "some/path/to/file"
>>> files_to_backup = read_data_from_file(file_name)

>>> pprint({key: val for key, val in globals().items() if '__' not in key})
{'file_name': 'some/path/to/file',
 'files_to_backup': 'some/path/to/file/bar',
 'pprint': <function pprint at 0x03454CD8>,
 'read_data_from_file': <function read_data_from_file at 0x03454C90>}

See that foo and bar is not seen in Global namespace,have to call function read_data_from_file.

The problem is these two variables might be used else where in my script, keeping them hidden inside a function will make it more difficult to use. You could return a dictionary of items, but it seems unnecessarily complicated. 

It's not so complicated you make the call  when needed or function can also bye passed to other function.
If all this get to complicated,then it can be time to think of using Classes to structure code.

The only way to hide a variable is inside a function.

Both function and classes(own namespace),keep variables local so they don't pollute Global namespace.