Add support for 'docker cp' to write to stdout
Closes
@@ -757,12 +757,15 @@ Supported `Dockerfile` instructions: `CMD`, `ENTRYPOINT`, `ENV`, `EXPOSE`,
## cp
-Copy files/folders from a container's filesystem to the host
-path. Paths are relative to the root of the filesystem.
+Copy files/folders from a container's filesystem to the
+path. Use '-' to write the data as a tar file to STDOUT.
+Paths are relative to the root of the filesystem.
- Usage: docker cp CONTAINER:PATH HOSTPATH
+ Usage: docker cp CONTAINER:PATH HOSTPATH|-
+
+ Copy files/folders from the PATH to the HOSTPATH. Use '-' to write the data
+ as a tar file to STDOUT.
- Copy files/folders from the PATH to the HOSTPATH
## create
