[Nix-dev] How to delete old generations and GC them, without GCing anything else?

[Kosyrev Serge]

Vladimír Čunát <vcunat at gmail.com> writes:
> On 03/06/2016 01:10 PM, Matthias Beyer wrote:
>> I want to remove old system generations and GC the packages, _without_ removing
>> anything else but these generations and their packages.
>
> I would `nix-store --gc --print-dead` before and after deleting the
> generations, and then I would use `comm` to compute the difference and
> remove it by `nix-store --gc --delete`.

How does this differ from deleting

  /nix/var/nix/gcroots/profiles/system/system-{old,old,old,old}-link

and then running `nix-store --gc`?

-- 
с уважениeм / respectfully,
Косырев Сергей