Add 'nix edit' manpage

2 files changed, 35 insertions, 7 deletions

diff --git a/src/nix/edit.cc b/src/nix/edit.cc
index 51c16f5a9..6472dd27a 100644
--- a/src/nix/edit.cc
+++ b/src/nix/edit.cc
@@ -15,14 +15,11 @@ struct CmdEdit : InstallableCommand
         return "open the Nix expression of a Nix package in $EDITOR";
     }
 
-    Examples examples() override
+    std::string doc() override
     {
-        return {
-            Example{
-                "To open the Nix expression of the GNU Hello package:",
-                "nix edit nixpkgs#hello"
-            },
-        };
+        return
+          #include "edit.md"
+          ;
     }
 
     Category category() override { return catSecondary; }
diff --git a/src/nix/edit.md b/src/nix/edit.md
new file mode 100644
index 000000000..80563d06b
--- /dev/null
+++ b/src/nix/edit.md
@@ -0,0 +1,31 @@
+R""(
+
+# Examples
+
+* Open the Nix expression of the GNU Hello package:
+
+  ```console
+  # nix edit nixpkgs#hello
+  ```
+
+* Get the filename and line number used by `nix edit`:
+
+  ```console
+  # nix eval --raw nixpkgs#hello.meta.position
+  /nix/store/fvafw0gvwayzdan642wrv84pzm5bgpmy-source/pkgs/applications/misc/hello/default.nix:15
+  ```
+
+# Description
+
+This command opens the Nix expression of a derivation in an
+editor. The filename and line number of the derivation are taken from
+its `meta.position` attribute. Nixpkgs' `stdenv.mkDerivation` sets
+this attribute to the location of the definition of the
+`meta.description`, `version` or `name` derivation attributes.
+
+The editor to invoke is specified by the `EDITOR` environment
+variable. It defaults to `cat`. If the editor is `emacs`, `nano` or
+`vim`, it is passed the line number of the derivation using the
+argument `+<lineno>`.
+
+)""