On Sun, 2012-04-08 at 20:08 -0400, Richard Stallman wrote:
>            When the user sets
>    the environment, it frobs PATH to refer to each bin/ directory.
>
>        Does that mean PATH is a list of hundreds of such directories?
>
>     As I understand it, yes.

Alfred, You doing it wrong.

>
> Does having so many dirs in PATH make it noticeably slower to run a
> command?
>
> I wonder why they don't populate /usr/bin and ~/bin with the
> installed commands.  Is it just to make it "functional",
> or is there a practical reason?

nix maintains symlinks to current "virtual" environment in ~/.nix/bin

If 3 of 4 versions of emacs installed you can choose one of them as
'emacs' and other can be available as 'emacs-*'.