Add 'nix copy' manpage

src/nix/copy.cc

@@ -54,32 +54,11 @@ struct CmdCopy : StorePathsCommand
         return "copy paths between Nix stores";
     }
 
-    Examples examples() override
+    std::string doc() override
     {
-        return {
-            Example{
-                "To copy Firefox from the local store to a binary cache in file:///tmp/cache:",
-                "nix copy --to file:///tmp/cache $(type -p firefox)"
-            },
-            Example{
-                "To copy the entire current NixOS system closure to another machine via SSH:",
-                "nix copy --to ssh://server /run/current-system"
-            },
-            Example{
-                "To copy a closure from another machine via SSH:",
-                "nix copy --from ssh://server /nix/store/a6cnl93nk1wxnq84brbbwr6hxw9gp2w9-blender-2.79-rc2"
-            },
-#ifdef ENABLE_S3
-            Example{
-                "To copy Hello to an S3 binary cache:",
-                "nix copy --to s3://my-bucket?region=eu-west-1 nixpkgs#hello"
-            },
-            Example{
-                "To copy Hello to an S3-compatible binary cache:",
-                "nix copy --to s3://my-bucket?region=eu-west-1&endpoint=example.com nixpkgs#hello"
-            },
-#endif
-        };
+        return
+          #include "copy.md"
+          ;
     }
 
     Category category() override { return catSecondary; }

src/nix/copy.md

@@ -0,0 +1,58 @@
+R""(
+
+# Examples
+
+* Copy Firefox from the local store to a binary cache in `/tmp/cache`:
+
+  ```console
+  # nix copy --to file:///tmp/cache $(type -p firefox)
+  ```
+
+  Note the `file://` - without this, the destination is a chroot
+  store, not a binary cache.
+
+* Copy the entire current NixOS system closure to another machine via
+  SSH:
+
+  ```console
+  # nix copy -s --to ssh://server /run/current-system
+  ```
+
+  The `-s` flag causes the remote machine to try to substitute missing
+  store paths, which may be faster if the link between the local and
+  remote machines is slower than the link between the remote machine
+  and its substituters (e.g. `https://cache.nixos.org`).
+
+* Copy a closure from another machine via SSH:
+
+  ```console
+  # nix copy --from ssh://server /nix/store/a6cnl93nk1wxnq84brbbwr6hxw9gp2w9-blender-2.79-rc2
+  ```
+
+* Copy Hello to a binary cache in an Amazon S3 bucket:
+
+  ```console
+  # nix copy --to s3://my-bucket?region=eu-west-1 nixpkgs#hello
+  ```
+
+  or to an S3-compatible storage system:
+
+  ```console
+  # nix copy --to s3://my-bucket?region=eu-west-1&endpoint=example.com nixpkgs#hello
+  ```
+
+  Note that this only works if Nix is built with AWS support.
+
+* Copy a closure from `/nix/store` to the chroot store `/tmp/nix/nix/store`:
+
+  ```console
+  # nix copy --to /tmp/nix nixpkgs#hello --no-check-sigs
+  ```
+
+# Description
+
+`nix copy` copies store path closures between two Nix stores. The
+source store is specified using `--from` and the destination using
+`--to`. If one of these is omitted, it defaults to the local store.
+
+)""