FAQ/Why not use nix-env -i foo?
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Why not use nix-env -i hello?
nix-env -i hello
is slower and tends to be less precise than nix-env -f '<nixpkgs>' -iA hello
. This is because it will evaluate all of nixpkgs searching for packages with the name hello
, and install the one determined to be the latest (which may not even be the one that you want). Meanwhile, with -A
, nix-env will evaluate only the given attribute in nixpkgs. This will be significantly faster, consume significantly less memory, and more likely get you what you want.
nix-env -u
has the same problem, searching for all the packages in the user environment by name and upgrading them. This may lead to unwanted major-version upgrades like JDK 8 → JDK 9. If you want to have a declarative user environment, you may wish to use Home Manager. It is also possible to home-bake a pure nix solution like LnL's. With this setup, you can update your packages by simply running nix-rebuild
.