diff --git a/cmd/version.go b/cmd/version.go
index 6f2d6b52..cec80ec2 100644
--- a/cmd/version.go
+++ b/cmd/version.go
@@ -11,7 +11,7 @@ var (
 	GitDescribe string
 
 	// Version is main version number that is being run at the moment.
-	Version = "4.2.0"
+	Version = "4.2.1"
 
 	// VersionPrerelease is a pre-release marker for the version. If this is "" (empty string)
 	// then it means that it is a final release. Otherwise, this is a pre-release
diff --git a/github-action/Dockerfile b/github-action/Dockerfile
index d3839f8b..0b3bcecd 100644
--- a/github-action/Dockerfile
+++ b/github-action/Dockerfile
@@ -1,4 +1,4 @@
-FROM mikefarah/yq:4.2.0
+FROM mikefarah/yq:4.2.1
 
 COPY entrypoint.sh /entrypoint.sh
 
diff --git a/pkg/yqlib/candidate_node.go b/pkg/yqlib/candidate_node.go
index f9f9e0cc..dd34a811 100644
--- a/pkg/yqlib/candidate_node.go
+++ b/pkg/yqlib/candidate_node.go
@@ -40,6 +40,7 @@ func (n *CandidateNode) Copy() (*CandidateNode, error) {
 
 // updates this candidate from the given candidate node
 func (n *CandidateNode) UpdateFrom(other *CandidateNode) {
+
 	n.UpdateAttributesFrom(other)
 	n.Node.Content = other.Node.Content
 	n.Node.Value = other.Node.Value
diff --git a/pkg/yqlib/doc/Assign.md b/pkg/yqlib/doc/Assign.md
index faba7f67..a0b7ce5f 100644
--- a/pkg/yqlib/doc/Assign.md
+++ b/pkg/yqlib/doc/Assign.md
@@ -34,6 +34,27 @@ a:
   g: foof
 ```
 
+## Update node from another file
+Note this will also work when the second file is a scalar (string/number)
+
+Given a sample.yml file of:
+```yaml
+a: apples
+```
+And another sample another.yml file of:
+```yaml
+b: bob
+```
+then
+```bash
+yq eval-all 'select(fileIndex==0).a = select(fileIndex==1) | select(fileIndex==0)' sample.yml another.yml
+```
+will output
+```yaml
+a:
+  b: bob
+```
+
 ## Update node to be the sibling value
 Given a sample.yml file of:
 ```yaml
diff --git a/pkg/yqlib/doc/File Operators.md b/pkg/yqlib/doc/File Operators.md
index 946dfee9..c7182ee5 100644
--- a/pkg/yqlib/doc/File Operators.md	
+++ b/pkg/yqlib/doc/File Operators.md	
@@ -16,7 +16,7 @@ yq eval 'filename' sample.yml
 ```
 will output
 ```yaml
-sample.yaml
+sample.yml
 ```
 
 ## Get file index
diff --git a/pkg/yqlib/operator_assign.go b/pkg/yqlib/operator_assign.go
index 82c7db04..f98e232f 100644
--- a/pkg/yqlib/operator_assign.go
+++ b/pkg/yqlib/operator_assign.go
@@ -33,7 +33,9 @@ func AssignUpdateOperator(d *dataTreeNavigator, matchingNodes *list.List, pathNo
 		first := rhs.Front()
 
 		if first != nil {
-			candidate.UpdateFrom(first.Value.(*CandidateNode))
+			rhsCandidate := first.Value.(*CandidateNode)
+			rhsCandidate.Node = UnwrapDoc(rhsCandidate.Node)
+			candidate.UpdateFrom(rhsCandidate)
 		}
 	}
 	// // if there was nothing given, perhaps we are creating a new yaml doc
diff --git a/pkg/yqlib/operator_assign_test.go b/pkg/yqlib/operator_assign_test.go
index f3acf2f0..dc397c86 100644
--- a/pkg/yqlib/operator_assign_test.go
+++ b/pkg/yqlib/operator_assign_test.go
@@ -20,6 +20,16 @@ var assignOperatorScenarios = []expressionScenario{
 			"D0, P[], (doc)::{a: {g: foof}}\n",
 		},
 	},
+	{
+		description:    "Update node from another file",
+		subdescription: "Note this will also work when the second file is a scalar (string/number)",
+		document:       `{a: apples}`,
+		document2:      "{b: bob}",
+		expression:     `select(fileIndex==0).a = select(fileIndex==1) | select(fileIndex==0)`,
+		expected: []string{
+			"D0, P[], (doc)::{a: {b: bob}}\n",
+		},
+	},
 	{
 		description: "Update node to be the sibling value",
 		document:    `{a: {b: child}, b: sibling}`,
diff --git a/pkg/yqlib/operators_test.go b/pkg/yqlib/operators_test.go
index 95047a05..46565916 100644
--- a/pkg/yqlib/operators_test.go
+++ b/pkg/yqlib/operators_test.go
@@ -18,6 +18,7 @@ type expressionScenario struct {
 	description           string
 	subdescription        string
 	document              string
+	document2             string
 	expression            string
 	expected              []string
 	skipDoc               bool
@@ -41,6 +42,14 @@ func testScenario(t *testing.T, s *expressionScenario) {
 			t.Error(err, s.document, s.expression)
 			return
 		}
+		if s.document2 != "" {
+			moreInputs, err := readDocuments(strings.NewReader(s.document2), "another.yml", 1)
+			if err != nil {
+				t.Error(err, s.document, s.expression)
+				return
+			}
+			inputs.PushBackList(moreInputs)
+		}
 	} else {
 		candidateNode := &CandidateNode{
 			Document:  0,
@@ -92,7 +101,7 @@ func copyFromHeader(title string, out *os.File) error {
 	return err
 }
 
-func formatYaml(yaml string) string {
+func formatYaml(yaml string, filename string) string {
 	var output bytes.Buffer
 	printer := NewPrinter(bufio.NewWriter(&output), false, true, false, 2, true)
 
@@ -101,7 +110,7 @@ func formatYaml(yaml string) string {
 		panic(err)
 	}
 	streamEvaluator := NewStreamEvaluator()
-	err = streamEvaluator.Evaluate("sample.yaml", strings.NewReader(yaml), node, printer)
+	err = streamEvaluator.Evaluate(filename, strings.NewReader(yaml), node, printer)
 	if err != nil {
 		panic(err)
 	}
@@ -136,25 +145,42 @@ func documentScenarios(t *testing.T, title string, scenarios []expressionScenari
 				writeOrPanic(w, "\n\n")
 			}
 			formattedDoc := ""
+			formattedDoc2 := ""
+			command := "eval"
 			if s.document != "" {
 				if s.dontFormatInputForDoc {
 					formattedDoc = s.document + "\n"
 				} else {
-					formattedDoc = formatYaml(s.document)
+					formattedDoc = formatYaml(s.document, "sample.yml")
 				}
-				//TODO: pretty here
-				writeOrPanic(w, "Given a sample.yml file of:\n")
 
+				writeOrPanic(w, "Given a sample.yml file of:\n")
 				writeOrPanic(w, fmt.Sprintf("```yaml\n%v```\n", formattedDoc))
+
+				files := "sample.yml"
+
+				if s.document2 != "" {
+					if s.dontFormatInputForDoc {
+						formattedDoc2 = s.document2 + "\n"
+					} else {
+						formattedDoc2 = formatYaml(s.document2, "another.yml")
+					}
+
+					writeOrPanic(w, "And another sample another.yml file of:\n")
+					writeOrPanic(w, fmt.Sprintf("```yaml\n%v```\n", formattedDoc2))
+					files = "sample.yml another.yml"
+					command = "eval-all"
+				}
+
 				writeOrPanic(w, "then\n")
 				if s.expression != "" {
-					writeOrPanic(w, fmt.Sprintf("```bash\nyq eval '%v' sample.yml\n```\n", s.expression))
+					writeOrPanic(w, fmt.Sprintf("```bash\nyq %v '%v' %v\n```\n", command, s.expression, files))
 				} else {
-					writeOrPanic(w, "```bash\nyq eval sample.yml\n```\n")
+					writeOrPanic(w, fmt.Sprintf("```bash\nyq %v %v\n```\n", command, files))
 				}
 			} else {
 				writeOrPanic(w, "Running\n")
-				writeOrPanic(w, fmt.Sprintf("```bash\nyq eval --null-input '%v'\n```\n", s.expression))
+				writeOrPanic(w, fmt.Sprintf("```bash\nyq %v --null-input '%v'\n```\n", command, s.expression))
 			}
 
 			writeOrPanic(w, "will output\n")
@@ -162,23 +188,48 @@ func documentScenarios(t *testing.T, title string, scenarios []expressionScenari
 			var output bytes.Buffer
 			var err error
 			printer := NewPrinter(bufio.NewWriter(&output), false, true, false, 2, true)
-			streamEvaluator := NewStreamEvaluator()
+
+			node, err := treeCreator.ParsePath(s.expression)
+			if err != nil {
+				t.Error(fmt.Errorf("Error parsing expression %v of %v: %v", s.expression, s.description, err))
+				return
+			}
+
+			inputs := list.New()
 
 			if s.document != "" {
-				node, err := treeCreator.ParsePath(s.expression)
+				inputs, err = readDocuments(strings.NewReader(formattedDoc), "sample.yml", 0)
 				if err != nil {
-					t.Error(err, s.expression)
+					t.Error(err, s.document, s.expression)
+					return
 				}
-				err = streamEvaluator.Evaluate("sample.yaml", strings.NewReader(formattedDoc), node, printer)
-
-				if err != nil {
-					t.Error(err, s.expression)
+				if s.document2 != "" {
+					moreInputs, err := readDocuments(strings.NewReader(formattedDoc2), "another.yml", 1)
+					if err != nil {
+						t.Error(err, s.document, s.expression)
+						return
+					}
+					inputs.PushBackList(moreInputs)
 				}
 			} else {
-				err = streamEvaluator.EvaluateNew(s.expression, printer)
-				if err != nil {
-					t.Error(err, s.expression)
+				candidateNode := &CandidateNode{
+					Document:  0,
+					Filename:  "",
+					Node:      &yaml.Node{Tag: "!!null"},
+					FileIndex: 0,
 				}
+				inputs.PushBack(candidateNode)
+
+			}
+
+			results, err := treeNavigator.GetMatchingNodes(inputs, node)
+			if err != nil {
+				t.Error(err, s.expression)
+			}
+
+			err = printer.PrintResults(results)
+			if err != nil {
+				t.Error(err, s.expression)
 			}
 
 			writeOrPanic(w, fmt.Sprintf("```yaml\n%v```\n\n", output.String()))
diff --git a/snap/snapcraft.yaml b/snap/snapcraft.yaml
index 569bfb76..e0f36c92 100644
--- a/snap/snapcraft.yaml
+++ b/snap/snapcraft.yaml
@@ -1,5 +1,5 @@
 name: yq
-version: '4.2.0'
+version: '4.2.1'
 summary: A lightweight and portable command-line YAML processor
 description: |
   The aim of the project is to be the jq or sed of yaml files.