[Nix-dev] duplicate packages?

[Roland Koebler]

Hi,

I have Nix running on Debian with the default channel [*], and I noticed,
that -- although I only have a few packages installed -- many dependencies
are installed several times. I would like to understand, why.

[*] https://nixos.org/channels/nixpkgs-unstable nixpkgs


1. Many packages are installed several times with the same version
   number, e.g.:

   2pa9z1h2m0pyik4hr1ikfl6jvdg8j4pb-acl-2.2.52
   8c5s33f5mzfn9z3yhjprxnxzl19dg7p2-acl-2.2.52
   sk0b1r840b686zc2m8mzyw8yyq1aymqh-acl-2.2.52

   4vgjwvgf24jl3czzksai6mwsklvhgs4k-attr-2.4.47
   8z667vv1agvpd3iknmk94j0ix6bv413i-attr-2.4.47
   m8qi9jrz51lqn7x0mifa9kpwpsp3b7dq-attr-2.4.47

   fxkm8r0vpv88ld82jz0a00sjvh342wfl-avahi-0.6.31
   p817p19niamk0f06r5wvqvdqnym96r7w-avahi-0.6.31
   5wi7ja71s4wdjkzfghc4lkwrwc45fnf9-avahi-0.6.32

   d20f169ryps7ds2qak0r5n1f4hhxr80h-bash-4.3-p42
   d44582rghk696yw704sh5nbvbpnm69iv-bash-4.3-p42
   xag5ayq906w9zhlxs8wayv4kvpiyqphq-bash-4.3-p42

   0y480sh5b4hny3iq8fy3ppha0zllxxaw-boehm-gc-7.2f
   bw1p8rairfwv2yif2g1cc0yg8hv25mnl-boehm-gc-7.2f
   f24zx1r39kalz01q9kw7zcg1ngj7w2db-boehm-gc-7.2f

   98s2znxww6x7h2ch7cj1w5givahxmdna-glibc-2.23
   phffgv3pwihmpdyk8xsz3wv8ydysch8w-glibc-2.23

   ...

   I know that different build-inputs result in different hashes, but I
   would have expected a more homogeneous structure in nixpkgs (e.g.
   only one acl-2.2.52 in nixpkgs and not several ones), so that
   I don't need e.g. 3 times acl-2.2.52 or bash-4.3-p42.

   Is this because I use nixpkgs-unstable, and everything is moving
   there, and is this reduced in the NixOS-release-channels?
   Or is there some other reason?

2. Is there a way to clean this up?
   Either in the repository or locally?
   Or is there a reason why this should not be cleaned up?

3. Is there a simple way to find the nix-expression (e.g.
   default.nix-file) of an installed package / a path in
   the nix-store?
   And is there a way to know which directory in the nix-store
   belongs to which .drv-file?


thanks,
Roland