nixos-enter: move to pkgs/by-name

nixos/modules/installer/tools/tools.nix

@@ -64,16 +64,7 @@ let
     manPage = ./manpages/nixos-version.8;
   };
 
-  nixos-enter = makeProg {
-    name = "nixos-enter";
-    src = ./nixos-enter.sh;
-    inherit (pkgs) runtimeShell;
-    path = makeBinPath [
-      pkgs.util-linuxMinimal
-    ];
-    manPage = ./manpages/nixos-enter.8;
-  };
-
+  inherit (pkgs) nixos-enter;
 in
 
 {

pkgs/by-name/ni/nixos-enter/package.nix

@@ -0,0 +1,28 @@
+{
+  lib,
+  substituteAll,
+  runtimeShell,
+  installShellFiles,
+  util-linuxMinimal,
+}:
+substituteAll {
+  name = "nixos-enter";
+  src = ./nixos-enter.sh;
+
+  inherit runtimeShell;
+
+  path = lib.makeBinPath [
+    util-linuxMinimal
+  ];
+
+  dir = "bin";
+  isExecutable = true;
+
+  nativeBuildInputs = [ installShellFiles ];
+
+  postInstall = ''
+    installManPage ${./nixos-enter.8}
+  '';
+
+  meta.mainProgram = "nixos-enter";
+}