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Build and Install packages from files

While you could use nix-env -iA to look for packages by attribute path from nixpkgs, many times you will want to instead explicitly install packages from files.

From a file of a single derivation expression

Remember that every Nix source file is an expression. You can build and install packages from a file that is a derivation value.

test.txt

hello, i am test

value.nix

let
  pkgs = import <nixpkgs> {};
in
pkgs.stdenv.mkDerivation {
  name = "test.txt";
  src = ./test.txt;
  phases = ["installPhase"];
  installPhase = ''
    mkdir -p $out/test
    ln -s $src $out/test/text.txt
  '';
}

Usage

We can build this derivation and see the result as expected:

$ nix-build value.nix
/nix/store/some-hash-test.txt

$ cat result/test/text.txt
hello, i am test

And since our derivation outputs a directory for the root, we can install it:

$ nix-env -if value.nix
installing 'test.txt'
building '/nix/store/some-hash-user-environment.drv'...
created NNN symlinks in user environment

$ cat ~/.nix-profile/test/text.txt
hello, i am test

From a file of a function with default arguments returning a derivation

This is the most common pattern that you will see for installable derivations, which simply uses "formal arguments", a form of attribute sets, for a function.

{ pkgs ? import <nixpkgs> {} }:

pkgs.stdenv.mkDerivation {
  name = "test.txt";
  src = ./test.txt;
  phases = [ "installPhase" ];
  installPhase = ''
    ln -s $src $out
  '';
}

This can be built and installed in the same way, as the default args are provided for the formal arguments.

$ nix-build derivation-function.nix
/nix/store/some-hash-test.txt

From a set of derivations

This is mostly useful if you want to version control packages installed in your profile.

{ pkgs ? import <nixpkgs> {} }:

{
  inherit (pkgs)
    python
    mypy;
}
$ nix-env -if some-pkgs.nix
installing 'mypy-0.701'
installing 'python-2.7.16'
building '/nix/store/some-hash-user-environment.drv'...
created NNN symlinks in user environment

From a list of derivations

This is really the same as sets, but in many ways less convenient. If you'd like to use this, you might also find builtins.attrValues useful to convert any attribute sets you have to lists of the values.

{ pkgs ? import <nixpkgs> {} }:

[
  pkgs.python
  pkgs.mypy
]

The result of this installation will be the exact same as the example above.

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