set dircmd=/w/o/p

then press Enter, every time thereafter that you type

dir

the /w/o/p switches will be automatically applied. Of course, if you want only the /p switch, you can type

set dircmd=/p

and press Enter.

You can undo the /w or /o or /p on each instance by simply typing

dir /-switch whatever

For example, if you wanted to do a directory with only the /w switch, you could enter

dir /-p/-o

This is a nice trick that I've been using since DOS 5, and it's always made life easier for me. Note that when you exit the Command prompt window, the Dircmd setting returns to its default settings.