temp

source/new-flake/bash-flake/flake-3.nix

@@ -15,14 +15,6 @@
           pkgs.mkShell {
             packages = [ pkgs.cowsay ];
           };
-
-      aarch64-linux.default =
-        let
-          pkgs = import nixpkgs { system = "aarch64-linux"; };
-        in
-          pkgs.mkShell {
-            packages = [ pkgs.cowsay ];
-          };
     }; # devShells
 
     packages = {
@@ -40,24 +32,10 @@
                 mkdir -p $out/bin
                 cp $src/cow-hello.sh $out/bin
                 chmod +x $out/bin/cow-hello.sh
-              '';
-            buildInputs = [ pkgs.cowsay ];
-          }; # mkDerivation
 
-      aarch64-linux.default =
-        let
-          pkgs = import nixpkgs { system = "aarch64-linux"; };
-        in
-          pkgs.stdenv.mkDerivation {
-            name = "cow-hello.sh";
-            src = ./.;
-            unpackPhase = "true";
-            buildPhase = ":";
-            installPhase =
-              ''
-                mkdir -p $out/bin
-                cp $src/cow-hello.sh $out/bin
-                chmod +x $out/bin/cow-hello.sh
+                # modify the cow-hello.sh script so it can find cowsay
+                COWSAY=$(type -p cowsay)
+                sed "s_cowsay_"$COWSAY"_" --in-place $out/bin/cow-hello.sh
               '';
             buildInputs = [ pkgs.cowsay ];
           }; # mkDerivation

source/new-flake/bash-flake/flake-4.nix

@@ -5,24 +5,32 @@
     nixpkgs.url = "github:NixOS/nixpkgs";
   };
 
-  outputs = { self, nixpkgs }:
-    let
-      supportedSystems = [ "x86_64-linux" "aarch64-linux" ];
-      forEachSystem = nixpkgs.lib.genAttrs supportedSystems;
-      nixpkgsFor = forEachSystem (system: import nixpkgs { inherit system; });
+  outputs = { self, nixpkgs }: {
 
-    in {
-
-      devShells = forEachSystem (system:
-        let pkgs = nixpkgsFor.${system}; in {
-          default = pkgs.mkShell {
-              packages = [ pkgs.cowsay ];
+    devShells = {
+      x86_64-linux.default =
+        let
+          pkgs = import nixpkgs { system = "x86_64-linux"; };
+        in
+          pkgs.mkShell {
+            packages = [ pkgs.cowsay ];
           };
-      });
 
-      packages = forEachSystem (system:
-        let pkgs = nixpkgsFor.${system}; in {
-          default = pkgs.stdenv.mkDerivation {
+      aarch64-linux.default =
+        let
+          pkgs = import nixpkgs { system = "aarch64-linux"; };
+        in
+          pkgs.mkShell {
+            packages = [ pkgs.cowsay ];
+          };
+    }; # devShells
+
+    packages = {
+      x86_64-linux.default =
+        let
+          pkgs = import nixpkgs { system = "x86_64-linux"; };
+        in
+          pkgs.stdenv.mkDerivation {
             name = "cow-hello.sh";
             src = ./.;
             unpackPhase = "true";
@@ -32,10 +40,36 @@
                 mkdir -p $out/bin
                 cp $src/cow-hello.sh $out/bin
                 chmod +x $out/bin/cow-hello.sh
+
+                # modify the cow-hello.sh script so it can find cowsay
+                COWSAY=$(type -p cowsay)
+                sed "s_cowsay_"$COWSAY"_" --in-place $out/bin/cow-hello.sh
               '';
             buildInputs = [ pkgs.cowsay ];
           }; # mkDerivation
-      }); # packages
+
+      aarch64-linux.default =
+        let
+          pkgs = import nixpkgs { system = "aarch64-linux"; };
+        in
+          pkgs.stdenv.mkDerivation {
+            name = "cow-hello.sh";
+            src = ./.;
+            unpackPhase = "true";
+            buildPhase = ":";
+            installPhase =
+              ''
+                mkdir -p $out/bin
+                cp $src/cow-hello.sh $out/bin
+                chmod +x $out/bin/cow-hello.sh
+
+                # modify the cow-hello.sh script so it can find cowsay
+                COWSAY=$(type -p cowsay)
+                sed "s_cowsay_"$COWSAY"_" --in-place $out/bin/cow-hello.sh
+              '';
+            buildInputs = [ pkgs.cowsay ];
+          }; # mkDerivation
+    }; # packages
 
   }; # outputs
 }

source/new-flake/bash-flake/flake-5.nix

@@ -7,16 +7,9 @@
 
   outputs = { self, nixpkgs }:
     let
-
       supportedSystems = [ "x86_64-linux" "aarch64-linux" ];
-
       forEachSystem = nixpkgs.lib.genAttrs supportedSystems;
-
-      nixpkgsFor = forEachSystem (system: import nixpkgs {
-        inherit system;
-        config = { };
-        overlays = [ ];
-      });
+      nixpkgsFor = forEachSystem (system: import nixpkgs { inherit system; });
 
     in {
 
@@ -28,8 +21,8 @@
       });
 
       packages = forEachSystem (system:
-        let pkgs = nixpkgsFor.${system}; in rec {
-          hello = pkgs.stdenv.mkDerivation {
+        let pkgs = nixpkgsFor.${system}; in {
+          default = pkgs.stdenv.mkDerivation {
             name = "cow-hello.sh";
             src = ./.;
             unpackPhase = "true";
@@ -39,21 +32,14 @@
                 mkdir -p $out/bin
                 cp $src/cow-hello.sh $out/bin
                 chmod +x $out/bin/cow-hello.sh
+
+                # modify the cow-hello.sh script so it can find cowsay
+                COWSAY=$(type -p cowsay)
+                sed "s_cowsay_"$COWSAY"_" --in-place $out/bin/cow-hello.sh
               '';
             buildInputs = [ pkgs.cowsay ];
           }; # mkDerivation
-
-          default = hello;
       }); # packages
 
-      apps = forEachSystem (system:
-        let pkgs = nixpkgsFor.${system}; in rec {
-          hello = {
-            type = "app";
-            program = pkgs.lib.getExe self.packages.${system}.hello;
-          };
-
-          default = hello;
-      });
   }; # outputs
 }

source/new-flake/bash-flake/main.adoc0

@@ -130,7 +130,8 @@ $# nix develop --command sh
 
 Because we haven't added `flake.nix` to the git repository, it's essentially invisible to Nix.
 Let's correct that and try again.
-We'll also add the script to the git repository.
+We'll also add the script to the git repository
+(otherwise we would get a confusing message about the file being "missing").
 
 ....
 $ git add flake.nix cow-hello.sh
@@ -181,7 +182,7 @@ pkgs.stdenv.mkDerivation {
 }; # mkDerivation
 ....
 
-To update the flake, add the new lines below to `flake.nix`.
+Here's the updated `flake.nix`.
 Again, change `x86_64-linux` if needed to match your system architecture.
 
 ////
@@ -197,14 +198,37 @@ $# cat flake.nix
 Let's test the package.
 First, we should exit the development shell so we can verify that the flake dependencies are automatically loaded.
 Otherwise the script could use `cowsay` from the development shell.
+We'll also commit the changes to get rid of the warnings.
 
 ....
 $ exit
-$ nix run
+$ git commit -am "define package"
+$ nix run # fails
 ....
 
-If we hadn't added `cow-hello.sh` to the git repository,
-we would have an error about the file being missing.
+What went wrong?
+Although we made `cowsay` available in the runtime environment,
+the `cow-hello.sh` script can't find it.
+
+For now, we can just edit the script during the build phase.
+We'll see another way to handle this in <<#writeShellApplication>>.
+
+////
+$ cp ../flake-3.nix flake.nix
+////
+
+[source,nix,linenums,highlight="36..38"]
+.flake.nix (version 3)
+....
+$# cat flake.nix
+....
+
+Let's try running the flake again.
+
+....
+$ git commit -am "fill in cowsay path"
+$ nix run
+....
 
 [#multi-arch]
 == Supporting multiple architectures
@@ -216,11 +240,11 @@ Of course we want to test it on the new architecture,
 so we'll add an entry to `devShells` as well.
 
 ////
-$ cp ../flake-3.nix flake.nix
+$ cp ../flake-4.nix flake.nix
 ////
 
-[source,nix,linenums,highlight="19..25,47..63"]
-.flake.nix (version 3)
+[source,nix,linenums,highlight="19..25,51..71"]
+.flake.nix (version 4)
 ....
 $# cat flake.nix
 ....
@@ -228,6 +252,7 @@ $# cat flake.nix
 Let's make sure it still runs on our system.
 
 ....
+$ git commit -am "suport aarch64-linux"
 $ nix run
 ....
 
@@ -333,15 +358,16 @@ You may want to compare it carefully to the original version,
 in order to reassure yourself that the definitions are equivalent.
 
 ////
-$ cp ../flake-4.nix flake.nix
+$ cp ../flake-5.nix flake.nix
 ////
 
 [source,nix,linenums,highlight="10..12,16,17,23,24"]
-.flake.nix (version 4)
+.flake.nix (version 5)
 ....
 $# cat flake.nix
 ....
 
+Note that if we need to support another architecture, we only need to add it to line 10.
 Let's verify that it runs on our system.
 
 ....
@@ -393,11 +419,11 @@ https://nixos.org/manual/nixpkgs/stable/#chap-overlays[overlays].
 Putting everything together, we have:
 
 ////
-$ cp ../flake-5.nix flake.nix
+$ cp ../flake-6.nix flake.nix
 ////
 
-[source,nix,linenums,highlight="17,18,31,32,46,49..57"]
-.flake.nix (version 5)
+[source,nix,linenums,highlight="17,18,31,32,50,53..61"]
+.flake.nix (version 6)
 ....
 $# cat flake.nix
 ....

source/recipes/build/nixpkg/tempwork/flake.nix

@@ -1,42 +0,0 @@
-{
-  description = "a very simple and friendly flake";
-
-  inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs";
-    flake-utils.url = "github:numtide/flake-utils";
-  };
-
-  outputs = { self, nixpkgs, flake-utils }:
-    flake-utils.lib.eachDefaultSystem (system:
-      let
-        pkgs = import nixpkgs { inherit system; };
-      in
-      {
-        devShells = rec {
-          default = pkgs.mkShell {
-            packages = [ pkgs.cowsay ];
-          };
-        };
-
-        packages = rec {
-          hello = pkgs.writeShellApplication {
-            name = "hello-cow";
-
-            runtimeInputs = [
-              pkgs.cowsay
-            ];
-
-            text = ''
-              cowsay "hello";
-            '';
-          };
-          default = hello;
-        };
-
-        apps = rec {
-          hello = flake-utils.lib.mkApp { drv = self.packages.${system}.hello; };
-          default = hello;
-        };
-      }
-    );
-}

source/recipes/devshell/nix-non-flake/tempwork/flake.lock

@@ -18,6 +18,22 @@
         "type": "github"
       }
     },
+    "hello-nix": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1757705465,
+        "narHash": "sha256-sJCQ9+8Dy+QF9ISaupp42+mGbuXtFyqbX85tWzeNPOI=",
+        "ref": "refs/heads/main",
+        "rev": "56044f61231c996e4ab795de1da89e5f79db3f4f",
+        "revCount": 5,
+        "type": "git",
+        "url": "https://codeberg.org/mhwombat/hello-nix"
+      },
+      "original": {
+        "type": "git",
+        "url": "https://codeberg.org/mhwombat/hello-nix"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1760435515,
@@ -36,6 +52,7 @@
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
+        "hello-nix": "hello-nix",
         "nixpkgs": "nixpkgs"
       }
     },

source/recipes/devshell/nix-non-flake/tempwork/flake.nix

@@ -0,0 +1,27 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs";
+    flake-utils.url = "github:numtide/flake-utils";
+    hello-nix = {
+      url = "git+https://codeberg.org/mhwombat/hello-nix";
+      flake = false;
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, hello-nix }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+        helloNix = import hello-nix { inherit pkgs; };
+      in
+      {
+        devShells = rec {
+          default = pkgs.mkShell {
+            packages = [ helloNix ];
+          };
+        };
+      }
+    );
+}