pkgs.fetchFromGitHub

what is it?

building software with nix often requires downloading source code and other files from the internet. nixpkgs provides fetchers for different protocols and services. fetchers are functions that simplify downloading files. fetchFromGitHub is one, there are others like fetchFromGitLab, fetchFromBitbucket

generating a sha256

first populate the sha256 value with lib.fakeSha256

zsh.nix

programs.zsh = {
    plugins = [
      {
        name = "fzf-tab";
        src = pkgs.fetchFromGitHub {
          owner = "Aloxaf";
          repo = "fzf-tab";
          rev = "v1.1.2";
          sha256 = lib.fakeSha256;
        };
      }
    ];
};

then, get the correct value from the error response

❯ home-manager switch --flake .
warning: Git tree '/home/devuntu/src/nixos-config' is dirty
warning: Git tree '/home/devuntu/src/nixos-config' is dirty
warning: Git tree '/home/devuntu/src/nixos-config' is dirty
warning: Git tree '/home/devuntu/src/nixos-config' is dirty
error: hash mismatch in fixed-output derivation '/nix/store/lvh4i342aky21s0g57anxdsq8qm7sfi4-source.drv':
         specified: sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
            got:    sha256-Qv8zAiMtrr67CbLRrFjGaPzFZcOiMVEFLg1Z+N6VMhg=

replace lib.fakeSha256 with the value in the response (in this case, "sha256-Qv8zAiMtrr67CbLRrFjGaPzFZcOiMVEFLg1Z+N6VMhg=" )