cmd/config: support for stdin/stdout in source/sink

cmd/config/internal/commands/sink.go

@@ -7,6 +7,7 @@ import (
 	"github.com/spf13/cobra"
 	"sigs.k8s.io/kustomize/cmd/config/internal/generateddocs/commands"
 	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/kio/kioutil"
 )
 
 // GetSinkRunner returns a command for Sink.
@@ -18,7 +19,7 @@ func GetSinkRunner(name string) *SinkRunner {
 		Long:    commands.SinkLong,
 		Example: commands.SinkExamples,
 		RunE:    r.runE,
-		Args:    cobra.ExactArgs(1),
+		Args:    cobra.MaximumNArgs(1),
 	}
 	fixDocs(name, c)
 	r.Command = c
@@ -35,14 +36,18 @@ type SinkRunner struct {
 }
 
 func (r *SinkRunner) runE(c *cobra.Command, args []string) error {
+	var outputs []kio.Writer
+	if len(args) == 1 {
+		outputs = []kio.Writer{&kio.LocalPackageWriter{PackagePath: args[0]}}
+	} else {
+		outputs = []kio.Writer{&kio.ByteWriter{
+			Writer:           c.OutOrStdout(),
+			ClearAnnotations: []string{kioutil.PathAnnotation}},
+		}
+	}
+
 	err := kio.Pipeline{
-		Inputs: []kio.Reader{&kio.ByteReader{Reader: c.InOrStdin()}},
-		Outputs: []kio.Writer{
-			&kio.LocalPackageWriter{
-				PackagePath:      args[0],
-				ClearAnnotations: []string{"config.kubernetes.io/path"},
-			},
-		},
-	}.Execute()
+		Inputs:  []kio.Reader{&kio.ByteReader{Reader: c.InOrStdin()}},
+		Outputs: outputs}.Execute()
 	return handleError(c, err)
 }