13 files changed, 284 insertions, 3 deletions
diff --git a/3 Resources/Nix/Adding things to the nix store.md b/3 Resources/Nix/Adding things to the nix store.md
new file mode 100644
index 0000000..98b2c17
--- /dev/null
+++ b/3 Resources/Nix/Adding things to the nix store.md
@@ -0,0 +1,12 @@
+---
+tags:
+  - nix
+---
+It's possible to use `nix-prefetch-url`:
+```
+nixos main
+❯ nix-prefetch-url --name displaylink-610.zip https://www.synaptics.com/sites/default/files/exe_files/2024-10/DisplayLink%20USB%20Graphics%20Software%20for%20Ubuntu6.1-EXE.zip
+path is '/nix/store/a10lxg1y9hc5ida4npg2mrmymc8932hl-displaylink-610.zip'
+1b3w7gxz54lp0hglsfwm5ln93nrpppjqg5sfszrxpw4qgynib624
+
+```
+\ No newline at end of file
diff --git a/3 Resources/Nix/Cleaning the Nix store.md b/3 Resources/Nix/Cleaning the Nix store.md
new file mode 100644
index 0000000..4ec07c0
--- /dev/null
+++ b/3 Resources/Nix/Cleaning the Nix store.md
@@ -0,0 +1,11 @@
+---
+tags:
+  - nix
+references:
+  - https://www.reddit.com/r/NixOS/comments/10107km/how_to_delete_old_generations_on_nixos/
+  - https://nixos.org/manual/nixos/unstable/#sec-nix-gc
+---
+```
+sudo nix-collect-garbage -d
+sudo nixos-rebuild boot 
+```
+\ No newline at end of file
diff --git a/3 Resources/Nix/Flake.md b/3 Resources/Nix/Flake.md
index 754556f..d191989 100644
--- a/3 Resources/Nix/Flake.md
+++ b/3 Resources/Nix/Flake.md
@@ -18,5 +18,67 @@ In flakes dependencies have to be specified explicitly and MUST be locked to spe
 Output of a Flake is an arbitrary [[Zettelkast/Index/Nix]] value such as a package, [[NixOS]] module or library function.
 Commands `nix build` and `nix shell` will build the output `packages.<system>.default` unless we specify another output, for example: `nix shell .#checks.aarch64-linux.build`.
 
+
+**Inputs**
+```
+{
+  inputs = {
+    # GitHub repository as the data source, specifying the master branch.
+    # This is the most common input format.
+    nixpkgs.url = "github:Mic92/nixpkgs/master";
+    # Git URL, applicable to any Git repository using the https/ssh protocol.
+    git-example.url = "git+https://git.somehost.tld/user/path?ref=branch";
+    # Git URL by tag, applicable to any Git repository using the https/ssh protocol.
+    git-example-tag.url = "git+https://git.somehost.tld/user/path?tag=x.y.x";
+    # Github URL by pull request.
+    git-pr.url = "github:NixOS/nixpkgs?ref=pull/349351/head";
+    # Git URL with submodules, applicable to any Git repository using the https/ssh protocol. 
+    git-example-submodule.url = "git+https://git.somehost.tld/user/path?submodules=1";
+    # Archive File URL, needed in case your input use LFS.
+    # Regular git input doesn't support LFS yet.
+    git-example-lfs.url = "https://codeberg.org/solver-orgz/treedome/archive/master.tar.gz";
+    # Similar to fetching a Git repository, but using the ssh protocol
+    # with key authentication. Also uses the shallow=1 parameter
+    # to avoid copying the .git directory.
+    ssh-git-example.url = "git+ssh://git@github.com/ryan4yin/nix-secrets.git?shallow=1";
+    # It's also possible to directly depend on a local Git repository.
+    git-directory-example.url = "git+file:/path/to/repo?shallow=1";
+    # Using the `dir` parameter to specify a subdirectory.
+    nixpkgs.url = "github:foo/bar?dir=shu";
+    # Local folder (if using an absolute path, the 'path:' prefix can be omitted).
+    directory-example.url = "path:/path/to/repo";
+
+    # If the data source is not a flake, set flake=false.
+    # `flake=false` is usually used to include additional source code,
+    #   configuration files, etc.
+    # In Nix code, you can directly reference files within
+    #   it using "${inputs.bar}/xxx/xxx" notation.
+    # For example, import "${inputs.bar}/xxx/xxx.nix" to import a specific nix file,
+    # or use "${inputs.bar}/xx/xx" as a path parameter for certain options.
+    bar = {
+      url = "github:foo/bar/branch";
+      flake = false;
+    };
+
+    sops-nix = {
+      url = "github:Mic92/sops-nix";
+      # `follows` is the inheritance syntax within inputs.
+      # Here, it ensures that sops-nix's `inputs.nixpkgs` aligns with
+      # the current flake's inputs.nixpkgs,
+      # avoiding inconsistencies in the dependency's nixpkgs version.
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    # Lock the flake to a specific commit.
+    nix-doom-emacs = {
+      url = "github:vlaci/nix-doom-emacs?rev=238b18d7b2c8239f676358634bfb32693d3706f3";
+      flake = false;
+    };
+  };
+
+  outputs = { self, ... }@inputs: { ... };
+}
+```
+
 ---
 [Flakes Wiki](https://nixos.wiki/wiki/Flakes)
 \ No newline at end of file
diff --git a/3 Resources/Nix/Functional programming vs imperative.md b/3 Resources/Nix/Functional programming vs imperative.md
new file mode 100644
index 0000000..8c2619a
--- /dev/null
+++ b/3 Resources/Nix/Functional programming vs imperative.md
@@ -0,0 +1,26 @@
+---
+tags:
+  - programming
+  - nix
+---
+While working on a NixOS module I made a realisation on the difference between functional and imperative programming.
+I was trying to configure `systemd.tmpfiles.rules` to create directories for git repositories. After looking a bit how to iterate; i tried the following:
+```nix
+let
+  paths = ["abs_paths" ...]
+in
+{
+  map(p: systemd.tmpfiles.rules = ["d {$p} ..."];);
+}
+```
+This is very much originating from the imperative mindset; we loop over a list and then do stuff like setting variables and calling other functions. However in functional programming we do not! This is the correct version in functional programming:
+```nix
+let
+  paths = [ "abs_paths" ... ];
+in
+{
+  systemd.tmpfiles.rules = map(p: "d ${p} ..") paths;
+}
+```
+
+Functions are pure, we can't assign stuff inside of their bodies because that would make them impure. Instead we can just return a value; in this case an array and *then* assign it.
+\ No newline at end of file
diff --git a/3 Resources/Nix/Generating Nix expressions.md b/3 Resources/Nix/Generating Nix expressions.md
new file mode 100644
index 0000000..347a7af
--- /dev/null
+++ b/3 Resources/Nix/Generating Nix expressions.md
@@ -0,0 +1,7 @@
+---
+tags:
+  - nix
+---
+From this repo it looks like we can convert JSON into Nix using `nix-instantiate --expr --eval builtins.fromJSON <jsonfile> `
+
+https://github.com/Janik-Haag/nm2nix/blob/main/nm2nix.py
+\ No newline at end of file
diff --git a/3 Resources/Nix/Home-manager systemd.md b/3 Resources/Nix/Home-manager systemd.md
new file mode 100644
index 0000000..d4a1460
--- /dev/null
+++ b/3 Resources/Nix/Home-manager systemd.md
@@ -0,0 +1,35 @@
+---
+tags:
+  - nix
+  - home-manager
+  - systemd
+---
+Config options start with `systemd.user`
+
+Home-manager manages the enabling and such based on the dependencies of the unit.
+So we can something like
+```
+Install = {
+  WantedBy = [ "default.target" ];
+};
+```
+
+And it will enable it.
+
+Another example
+```nix
+systemd.user.services.astal = {
+  Unit = {
+    Description = "Runs the astal bar instance";
+    After = [ "graphical-session-pre.target" ];
+  };
+  Service = {
+    Type = "exec";
+    ExecStart = "some-bin";
+  };
+
+  Install = {
+    WantedBy = [ "graphical-session.target" ];
+  };
+};
+```
+\ No newline at end of file
diff --git a/3 Resources/Nix/Hostname changes.md b/3 Resources/Nix/Hostname changes.md
new file mode 100644
index 0000000..0aaa324
--- /dev/null
+++ b/3 Resources/Nix/Hostname changes.md
@@ -0,0 +1,6 @@
+---
+tags:
+  - nixos
+  - nixos-anywhere
+---
+When using nixos-anywhere and passing it a hostname; it changes during kexec to nixos-anywhere. But the script will continue attempting to connect to whatever we gave it. Therefore we should pass it an IP address instead.
+\ No newline at end of file
diff --git a/3 Resources/Nix/Interpolation.md b/3 Resources/Nix/Interpolation.md
new file mode 100644
index 0000000..bbdb457
--- /dev/null
+++ b/3 Resources/Nix/Interpolation.md
@@ -0,0 +1,7 @@
+---
+tags:
+  - nix
+references:
+  - https://nix.dev/manual/nix/2.24/language/syntax#string-literal
+---
+In a normal string we can use backslash to escape. In indented strings we should use double backticks.
+\ No newline at end of file
diff --git a/3 Resources/Nix/Nix Manual References.md b/3 Resources/Nix/Nix Manual References.md
new file mode 100644
index 0000000..486a2fe
--- /dev/null
+++ b/3 Resources/Nix/Nix Manual References.md
@@ -0,0 +1,7 @@
+---
+tags:
+  - nix
+references:
+  - https://nix.dev/manual/nix/2.24/language/builtins.html
+  - https://nixos.org/manual/nixpkgs/stable
+---
diff --git a/3 Resources/Nix/Nix collect garbage.md b/3 Resources/Nix/Nix collect garbage.md
new file mode 100644
index 0000000..65e6aad
--- /dev/null
+++ b/3 Resources/Nix/Nix collect garbage.md
@@ -0,0 +1,10 @@
+---
+tags:
+  - nix
+references:
+  - https://www.reddit.com/r/NixOS/comments/10107km/how_to_delete_old_generations_on_nixos/
+---
+```
+sudo nix-collect-garbage -d
+sudo nixos-rebuild boot 
+```
+\ No newline at end of file
diff --git a/3 Resources/Nix/NixOS Modules.md b/3 Resources/Nix/NixOS Modules.md
new file mode 100644
index 0000000..1ab4c25
--- /dev/null
+++ b/3 Resources/Nix/NixOS Modules.md
@@ -0,0 +1,56 @@
+---
+tags:
+  - nix
+  - nixos
+references:
+  - https://nixos.org/manual/nixos/unstable/#sec-writing-modules
+  - https://nixos.org/manual/nixpkgs/stable/#module-system-lib-evalModules
+  - https://nix.dev/tutorials/module-system/
+  - llk
+---
+Extra care must be taken when writing systemd services using Exec* due to interpolation and such. `utils.escapeSystemdExecArg` and `utils.escapeSystemdExecArg` exist.
+
+```nix
+{
+  options = {
+    name = mkOption {
+      type = type specification;
+      default = default value;
+      example = example value;
+      description = "Description for use in the NixOS manual.";
+    };
+  };
+}
+```
+
+**A list of submodules**
+```nix
+{
+  options.mod = mkOption {
+    description = "submodule example";
+    type = with types; listOf (submodule {
+      options = {
+        foo = mkOption {
+          type = int;
+        };
+        bar = mkOption {
+          type = str;
+        };
+      };
+    });
+  };
+}
+```
+
+
+**Testing**
+```nix eval.nix
+let
+	pkgs = import <nixpkgs> {};
+	res = pkgs.lib.evalModules {
+		modules = [./git-repos.nix];
+	};
+in
+res.config
+```
+`nix-instantiate --eval eval.nix`
+\ No newline at end of file
diff --git a/3 Resources/Nix/Remote nixos rebuild lacking valid signature.md b/3 Resources/Nix/Remote nixos rebuild lacking valid signature.md
new file mode 100644
index 0000000..82e03b2
--- /dev/null
+++ b/3 Resources/Nix/Remote nixos rebuild lacking valid signature.md
@@ -0,0 +1,13 @@
+---
+tags:
+  - nix
+  - nixos
+references:
+  - https://nixos.wiki/wiki/Nixos-rebuild
+---
+When rebuilding on a remote it might spew an error containing: "is lacking a valid signature". To remedy this we need to add our non-root user as a trusted user;
+```
+nix.extraOptions = ''
+  trusted-users jras
+'';
+```
+\ No newline at end of file
diff --git a/3 Resources/Nix/Shell.nix.md b/3 Resources/Nix/Shell.md
index 13715c2..08e7c53 100644
--- a/3 Resources/Nix/Shell.nix.md
+++ b/3 Resources/Nix/Shell.md
@@ -1,6 +1,35 @@
-#nix #shell
-
 ---
+tags:
+  - nix
+  - shell
+---
+Basic invocation: `nix-shell -p [ pkgs ... ]`
+
+# Shebang
+```
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash -p bash
+
+do stuff
+```
+
+Different interpreters can be set with the `-i` option such as python
+```
+#! /usr/bin/env nix-shell
+#! nix-shell -i python3 -p python3
+
+print("hello world")
+```
+
+The `-I` option can be used to pin nixpkgs
+```
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash
+#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/aed4b19d312525ae7ca9bceb4e1efe3357d0e2eb.tar.gz
+
+echo hello world
+```
+# Shell.nix
 Can be used to set up per dir environments, e.g using direnv to automatically activate them.
 ## Python
 https://nixos.org/manual/nixpkgs/stable/#python
@@ -38,5 +67,5 @@ let
 in python311.withPackages (ps: with ps; [ numpy my_toolz ]) ).env
 ```
 
-The [[Import]] is required here because imports a nix expression from another source, in this case nixpkgs.
+					The [[Import]] is required here because imports a nix expression from another source, in this case nixpkgs.
 It is not required at line two, because python310Packages itself is already in the local scope.
 \ No newline at end of file