What's the difference between BSD-style and Unix-style command line options?

Question

I tried to google it but to no avail. Can anybody help me with this?

Answer 1

It depends on the program. ps is the one that you encounter the most often - somebody who grew up in a BSD environment will type ps auwwx while somebody who grew up in a System V environment will type ps -ef even though ps these days supports both types of options now.

Answer 2

One of the major differences across the platform is positional arguments. Most of the command line utilities will enforce that flags come before positional arguments. That is, on a GNU system, the following is fine:

ls / -la

On BSD, these are typically not valid. Obviously, this isn't the extent of the differences between the two, but its one of the differences that drives me up the wall when I switch between them.