Add update-date helper

flake.nix

@@ -19,7 +19,7 @@
       perSystem = { config, self', inputs', pkgs, system, ... }:
         let
           inherit (gitignore.lib) gitignoreSource;
-          inherit (pkgs.callPackage ./nix { }) fonts optimize-images;
+          inherit (pkgs.callPackage ./nix { }) fonts optimize-images update-date;
           inherit (fonts) copyFonts linkFonts;
           caddyfile-syntax = "${inputs.caddyfile-syntax}/Caddyfile.sublime-syntax";
           buildSite = { prod }:
@@ -40,7 +40,7 @@
             pname = "personal-site";
             version = "2022-10-23";
             src = gitignoreSource ./.;
-            nativeBuildInputs = [ optimize-images zola ];
+            nativeBuildInputs = [ optimize-images update-date zola ];
             configurePhase = copyFonts + ''
               mkdir -p extra/syntax
               cp ${caddyfile-syntax} extra/syntax
@@ -54,7 +54,7 @@
             buildPhase = buildSite { prod = false; };
           });
           devShells.default = with pkgs; mkShell {
-            packages = [ optimize-images zola ];
+            packages = [ optimize-images update-date zola ];
             shellHook = linkFonts + ''
               mkdir -p extra/syntax
               ln -snf ${caddyfile-syntax} extra/syntax

nix/default.nix

@@ -1,4 +1,5 @@
 { callPackage }: {
   fonts = callPackage ./fonts.nix { };
   optimize-images = callPackage ./optimize-images.nix { };
+  update-date = callPackage ./update-date.nix { };
 }

nix/update-date.nix

@@ -0,0 +1,10 @@
+{ coreutils, sd, writeShellScriptBin }:
+
+writeShellScriptBin "update-date" ''
+  export VERSION=$1
+  if [ -z "$VERSION" ]
+  then
+    export VERSION=$(${coreutils}/bin/date -I)
+  fi
+  ${sd}/bin/sd 'version = ".*"' 'version = "'$VERSION'"' flake.nix
+''