add nixify/flakify helper

README.md

@@ -214,6 +214,41 @@ $ touch shell.nix
 $ touch flake.nix
 ```
 
+## Shell integration
+
+To quickly add a default.nix/flake.nix to a project you can put the following snippets in your bashrc/zshrc
+
+```bash
+nixify() {
+  if [ ! -e ./.envrc ]; then
+    echo "use nix" > .envrc
+    direnv allow
+  fi
+  if [[ ! -e shell.nix ]] && [[ ! -e default.nix ]]; then
+    cat > default.nix <<'EOF'
+with import <nixpkgs> {};
+mkShell {
+  nativeBuildInputs = [
+    bashInteractive
+  ];
+}
+EOF
+    ${EDITOR:-vim} default.nix
+  fi
+}
+
+flakifiy() {
+  if [ ! -e flake.nix ]; then
+    nix flake new -t github:nix-community/nix-direnv .
+  elif [ ! -e .envrc ]; then
+    echo "use flake" > .envrc
+    direnv allow
+  fi
+  ${EDITOR:-vim} flake.nix
+}
+
+```
+
 ## Known Bugs
 
 At the moment `nix-direnv` depends on GNU Grep and a modern Bash version.