nix: add channel configuration and rework update process

nix/os/devices/default.nix

@@ -1,23 +1,25 @@
 { pkgs ? import <nixpkgs> {}
 , dir
-, rebuildarg ? null
+, rebuildarg
+, moreargs ? ""
 }:
 
 let
   diskId = (import ((builtins.getEnv "PWD")+"/${dir}/hw.nix") {}).hardware.encryptedDisk.diskId;
+  GIT_ROOT=''''$(git rev-parse --show-toplevel)'';
 
 in {
   rebuild = pkgs.writeScript "script" ''
     #!/usr/bin/env bash
     set -xe
 
-    pushd ${dir}
+    pushd ${GIT_ROOT}/${dir}
     export NIXOS_CONFIG="$PWD"/configuration.nix
     export INSTALL_ROOT="/mnt/$ID-root"
 
     [[ -e "''${NIXOS_CONFIG}" ]]
 
-    nixos-rebuild -I nixos-config=''${NIXOS_CONFIG} ${rebuildarg}
+    nixos-rebuild -I nixos-config=''${NIXOS_CONFIG} ${rebuildarg} ${moreargs}
     if test -L result; then
       rm result
     fi
@@ -52,7 +54,7 @@ in {
     #!/usr/bin/env bash
     set -xe
     ID=${diskId}
-    pushd ${dir}
+    pushd ${GIT_ROOT}/${dir}
     export NIXOS_CONFIG="$PWD"/configuration.nix
     export INSTALL_ROOT="/mnt/$ID-root"
 

nix/os/devices/steveej-laptop/pkg.nix

@@ -3,11 +3,8 @@
   ... }:
 
 let
-  gitpkgs = import /home/steveej/src/github/NixOS/nixpkgs {};
-  unstablepkgs = import <nixos-unstable> {};
 
-in
-{
+in {
   nixpkgs.config = {
     allowBroken = false;
     allowUnfree = true;

nix/os/devices/steveej-live-mmc-SL32G_0x259093f6/system.nix

@@ -1,5 +0,0 @@
-{ ... }:
-
-{
-  networking.hostName = "mmc-sandiskultra32gb"; # Define your hostname.
-}

nix/os/devices/steveej-rmvbl-mmc-SL32G_0x259093f6/system.nix

@@ -0,0 +1,5 @@
+{ ... }:
+
+{
+  networking.hostName = "steveej-rmvbl-mmc-SL32G_0x259093f6"; # Define your hostname.
+}