[Nix-dev] confused by the recent channels stuff

[Mathijs Kwik]

Hi all,

I saw some commits relating to ~/.nix-defexpr , so I decided to remove
(.bak) that directory for root and my own user.
It got recreated, but nix-env -qa \* didn't show any packages anymore.
After a bit of searching, I found that I should probably "nix-channel
--add http://nixos.org/releases/nixos/channels/nixos-unstable" as
root.
After doing that, and running nix-channel --update, the packages list
was back again.

However, I have some local packages in my /etc/nixos/nixpkgs, and they
are not available anymore.
So I guess channels are not for people who want to have some local
modifications.
Does this mean we need to setup the old nixpkgs_sys symlink manually
after a new installation?
And what does this mean for binary updates? Are they only available
through the channel from now on?

Some more info on how to use this stuff would be great.

Thanks,
Mathijs