nix-eval, nix-flake-{show, info, init}: add page (#20061)

Co-authored-by: Managor <42655600+Managor@users.noreply.github.com>
Co-authored-by: Sebastiaan Speck <12570668+sebastiaanspeck@users.noreply.github.com>
Co-authored-by: Ivan Baluta <ivanbaluta.dev@gmail.com>

pages/common/nix-eval.md

@@ -0,0 +1,28 @@
+# nix eval
+
+> Evaluate a Nix expression and print the result to `stdout`.
+> More information: <https://nix.dev/manual/nix/stable/command-ref/new-cli/nix3-eval.html>.
+
+- Evaluate Nix flake attributes in the current directory:
+
+`nix eval .#{{attributes}}`
+
+- Evaluate a given Nix expression:
+
+`nix eval --expr '{{your_expression}}'`
+
+- Evaluate a Nix expression from a specified file:
+
+`nix eval --file {{path/to/file}}`
+
+- Print the store path of the specified package from nixpkgs:
+
+`nix eval {{nixpkgs#pkg}} --raw`
+
+- Evaluate attributes from a flake directly from GitHub:
+
+`nix eval {{github:owner/repo#attributes}}`
+
+- Evaluate a given lambda function passing the specified package as argument:
+
+`nix eval {{nixpkgs#pkg}} --apply '{{lambda_function}}'`

pages/common/nix-flake-info.md

@@ -0,0 +1,16 @@
+# nix flake info
+
+> Show flake metadata.
+> More information: <https://nix.dev/manual/nix/stable/command-ref/new-cli/nix3-flake-info>.
+
+- Show flake metadata of the flake in the current directory:
+
+`nix flake info`
+
+- Show flake metadata from GitHub as a json on a single line:
+
+`nix flake info {{github:owner/repo}} --json --no-pretty`
+
+- Show flake metadata from Github as a multi-line indented json:
+
+`nix flake info {{github:owner/repo}} --json --pretty`

pages/common/nix-flake-init.md

@@ -0,0 +1,12 @@
+# nix flake init
+
+> Create a flake in the current directory from a template.
+> More information: <https://nix.dev/manual/nix/stable/command-ref/new-cli/nix3-flake-init.html>.
+
+- Create a new flake from the default template, in the current directory:
+
+`nix flake init`
+
+- Create a new flake with a specified template (see `nix flake show` for information about templates):
+
+`nix flake init {{[-t|--template]}} templates#{{your_template}}`

pages/common/nix-flake-show.md

@@ -0,0 +1,20 @@
+# nix flake show
+
+> Show outputs provided by a flake.
+> More information: <https://nix.dev/manual/nix/stable/command-ref/new-cli/nix3-flake-show.html>.
+
+- Show all the outputs of the flake in the current directory:
+
+`nix flake show`
+
+- Show all the outputs of a flake on GitHub and print the output as a json on a single line:
+
+`nix flake show {{github:owner/repo}} --json --no-pretty`
+
+- Show all the `legacyPackages` outputs of a flake on GitHub and print the output as a multi-line indented json:
+
+`nix flake show {{github:owner/repo}} --json --pretty --legacy`
+
+- List all available flake templates for `nix flake init`:
+
+`nix flake show templates`

pages/common/nix-flake.md

@@ -1,12 +1,9 @@
 # nix flake
 
 > Manage Nix flakes.
+> Some subcommands such as `init`, `show`, `info` have their own usage documentation.
 > More information: <https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-flake.html>.
 
-- Create a new flake (just the `flake.nix` file) from the default template, in the current directory:
-
-`nix flake init`
-
 - Update all inputs (dependencies) of the flake in the current directory:
 
 `nix flake update`
@@ -15,9 +12,13 @@
 
 `nix flake update {{input}}`
 
-- Show all the outputs of a flake on github:
+- Clone a GitHub repository containing a flake:
 
-`nix flake show {{github:owner/repo}}`
+`nix flake clone {{github:owner/repo#attributes}}`
+
+- Create missing lock file entries for a flake in a specified directory:
+
+`nix flake lock {{path/to/flake}}`
 
 - Display help: