[Nix-dev] How to actually get rid of things from the nix-env -qs list?

[Marc Weber]

Excerpts from Mateusz Kowalczyk's message of Mon Apr 28 10:39:11 +0000 2014:
> On 04/28/2014 09:23 AM, Marc Weber wrote:
> Is there a way to ask nix to tell me which one is active?
There is no active:yes/no

Example:

p-1.0:   /bin/foo
p-2.0:   /bin/foo-2.0

Then you'll have both in PATH

In yoru case I expect:

python-package-1.0:  lib/python-2.7/site-packages/foo.py
python-package-2.0:  lib/python-2.7/site-packages/foo.py

Thus if you link both the one which will be linked first should win.

How to find out?

follow the symlinks found in path ~/.nix-profiles/lib-python-2.7/site-packages-foo.py
to find out which one got linked.

But I agree, it might be helpful if there was not only a --set-flag prio
but also a --list-prios flag or such for nix-env, did I miss such?

No idea where those priorities get stored when set manually.

How to solve your problem? Don't use nix-env -i <every single package>,
instead you can use misc.collection
=> https://nixos.org/wiki/Howto_keep_multiple_packages_up_to_date_at_once

This illustrates one "declarative" approach to managing your custom
environment. It might make sense to have multiple collections such as
pythonPackages mailStuff etc.

Marc Weber