My personal Nix & NixOS FAQ
I use Nix and NixOS every day, but I still feel frustrated because I don't know how to perform some basic tasks. I have decided to put the questions I ask myself on this page, and hopefully fill in the answers little by little. This will serve both as a future reference (to me and others) and as a motivation to learn to use Nix properly.
Please do not hesitate to contact me to suggest answers or improvements.
- How can I build a package locally instead of downloading the binary?
- How can I get the Nix directory (containing the code and Nix files) of a package?
- How to find the Nix store path associated to an installed package?
- Is there a command to delete a specific derivation from the Nix store?
- If an error occurs during the upgrading of a package, how can I temporarily ignore this package's updates in order to upgrade the rest of the packages?
Many thanks to Andrew Miloradovsky and Daniel Barlow for their answers.
How can I build a package locally instead of downloading the binary?
Add --option substitute false, or set it globally. (search man nix.conf for “substitute”).
How can I get the Nix directory (containing the code and Nix files) of a package?
Here I simply copy Andrew Miloradovsy's answer:
It's all in ~/.nix-defexpr/channels_root/nixos/, or in the user's own channel(s). See there pkgs/top-level/all-packages.nix, where all the “packages” have to be registered: some are paths to an actual file with a Nix-expression, some are functions, generating the “packages” for each combination of inputs.
But you can't/shouldn't edit those. Clone the Nixpkgs repository instead and edit it in there.
How to find the Nix store path associated to an installed package?
If the package installed the command <command> in the PATH, you can do:
$ realpath `which <command>`Otherwise, you can use nix-build for this (though it has the side-effect of downloading/building the package if you didn't have it already, it won't add it to your current environment, so no practical difference except disk space).
$ nix-build '<nixpkgs>' -A hello
/nix/store/20liz5dns3dm13gbk5synzf5qjsdpf51-hello-2.10Is there a command to delete a specific derivation from the Nix store?
To be filled
If an error occurs during the upgrading of a package, how can I temporarily ignore this package's updates in order to upgrade the rest of the packages?
To be filled
