init nixos/activation script

modules/nix/README.md

@@ -1,6 +1,6 @@
 # Nix
 
-Commands for working with [nix](https://nixos.org/).
+Commands for working with [nix/nixos](https://nixos.org/).
 
 ### ns
 Shorthand search (`nix search nixpkgs ...`) with much nicer output.
@@ -24,3 +24,31 @@ Shorthand search (`nix search nixpkgs ...`) with much nicer output.
 ╰───┴────────────────┴──────────────────────────────────────────────────────────────┴─────────╯
 ```
 
+### activation-script
+
+Shows changed packages after running `nixos-rebuild switch/boot` and change in total size of installed packages. Changes that don't affect the installed size are filtered out. Intended to be added to `configuration.nix` of `NixOS`.
+
+```
+╭─────────────────┬─────────────┬─────────────┬───────────╮
+│ Package │ Old_Version │ New_Version │ Diff │
+├─────────────────┼─────────────┼─────────────┼───────────┤
+│ xwayland │ ∅ │ 24.1.0 │ 5.3 MB │
+│ lsp-plugins │ 1.2.15 │ 1.2.16 │ 1.1 MB │
+│ libei │ ∅ │ 1.2.1 │ 547.6 KB │
+│ libXfont2 │ ∅ │ 2.0.6 │ 270.0 KB │
+│ xkbcomp │ ∅ │ 1.4.7 │ 235.7 KB │
+│ font-util │ ∅ │ 1.4.1 │ 234.1 KB │
+│ libxkbfile │ ∅ │ 1.1.3 │ 174.6 KB │
+│ xfsprogs │ 6.6.0 │ 6.8.0 │ 61.0 KB │
+│ xcb-util-errors │ ∅ │ 1.0.1 │ 48.5 KB │
+│ libieee1284 │ 0.2.11 │ ∅ │ -123.1 KB │
+│ libgnomekbd │ 3.28.1 │ ∅ │ -702.0 KB │
+│ xwayland │ 24.1.0 │ ∅ │ -5.3 MB │
+│ libgweather │ 4.4.0 │ ∅ │ -23.8 MB │
+╰─────────────────┴─────────────┴─────────────┴───────────╯
+
+╭──────┬──────────╮
+│ Diff │ -22.0 MB │
+╰──────┴──────────╯
+```
+

modules/nix/activation-script

@@ -0,0 +1,11 @@
+### add to configuration.nix
+
+nix.settings.experimental-features = ["nix-command"];
+
+system.activationScripts.diff = ''
+ if [[ -e /run/current-system ]]; then
+ echo
+ ${pkgs.nushell}/bin/nu -c "let diff_closure = ${pkgs.nix}/bin/nix store diff-closures /run/current-system '$systemConfig'; if \$diff_closure != \"\" { let table = \$diff_closure | lines | where \$it =~ KiB | where \$it =~ → | parse -r '^(?<Package>\S+): (?<Old_Version>[^,]+)(?:.*) → (?<New_Version>[^,]+)(?:.*, )(?<DiffBin>.*)$' | insert Diff { get DiffBin | ansi strip | str trim -l -c '+' | into filesize } | reject DiffBin | sort-by -r Diff; print \$table; \$table | math sum }"
+ fi
+'';
+