Fixed cli doco

Dockerfile.dev

@@ -1,4 +1,4 @@
-FROM golang:1.13
+FROM golang:1.14
 
 COPY scripts/devtools.sh /opt/devtools.sh
 
@@ -9,15 +9,15 @@ RUN set -e -x \
 RUN set -ex \
     && buildDeps=' \
         build-essential \
-        python-dev \
+        python3-dev \
     ' \
     && apt-get update && apt-get install -y --no-install-recommends \
         $buildDeps \
-        python2.7 \
-        python-setuptools \
-        python-wheel \
-        python-pip \
-    && pip install --upgrade \
+        python3 \
+        python3-setuptools \
+        python3-wheel \
+        python3-pip \
+    && pip3 install --upgrade \
         pip \
         'Markdown>=2.6.9' \
         'mkdocs>=0.16.3' \

cmd/compare_test.go

@@ -0,0 +1,66 @@
+package cmd
+
+import (
+	"testing"
+
+	"github.com/mikefarah/yq/v3/test"
+)
+
+func TestCompareSameCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "compare ../examples/data1.yaml ../examples/data1.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := ``
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestCompareDifferentCmd(t *testing.T) {
+	forceOsExit = false
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "compare ../examples/data1.yaml ../examples/data3.yaml")
+
+	expectedOutput := `-a: simple # just the best
+-b: [1, 2]
++a: "simple" # just the best
++b: [1, 3]
+ c:
+   test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestComparePrettyCmd(t *testing.T) {
+	forceOsExit = false
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "compare -P ../examples/data1.yaml ../examples/data3.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := ` a: simple # just the best
+ b:
+ - 1
+-- 2
++- 3
+ c:
+   test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestComparePathsCmd(t *testing.T) {
+	forceOsExit = false
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "compare -P -ppv ../examples/data1.yaml ../examples/data3.yaml **")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := ` a: simple # just the best
+ b.[0]: 1
+-b.[1]: 2
++b.[1]: 3
+ c.test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}

cmd/constant.go

@@ -9,6 +9,8 @@ var customTag = ""
 var printMode = "v"
 var printLength = false
 var unwrapScalar = true
+var customStyle = ""
+var stripComments = false
 var collectIntoArray = false
 var writeInplace = false
 var writeScript = ""

cmd/delete_test.go

@@ -0,0 +1,223 @@
+package cmd
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/mikefarah/yq/v3/test"
+)
+
+func TestDeleteYamlCmd(t *testing.T) {
+	content := `a: 2
+b:
+  c: things
+  d: something else
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete %s b.c", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	expectedOutput := `a: 2
+b:
+  d: something else
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestDeleteDeepDoesNotExistCmd(t *testing.T) {
+	content := `a: 2`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete %s b.c", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	expectedOutput := `a: 2
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestDeleteSplatYaml(t *testing.T) {
+	content := `a: other
+b: [3, 4]
+c:
+  toast: leave
+  test: 1
+  tell: 1
+  tasty.taco: cool
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete %s c.te*", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	expectedOutput := `a: other
+b: [3, 4]
+c:
+  toast: leave
+  tasty.taco: cool
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestDeleteSplatArrayYaml(t *testing.T) {
+	content := `a: 2
+b:
+ hi:
+  - thing: item1
+    name: fred
+  - thing: item2
+    name: sam
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete %s b.hi[*].thing", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	expectedOutput := `a: 2
+b:
+  hi:
+  - name: fred
+  - name: sam
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestDeleteSplatPrefixYaml(t *testing.T) {
+	content := `a: 2
+b:
+ hi:
+   c: things
+   d: something else
+ there:
+   c: more things
+   d: more something else
+ there2:
+   c: more things also
+   d: more something else also
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete %s b.there*.c", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	expectedOutput := `a: 2
+b:
+  hi:
+    c: things
+    d: something else
+  there:
+    d: more something else
+  there2:
+    d: more something else also
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestDeleteYamlArrayCmd(t *testing.T) {
+	content := `- 1
+- 2
+- 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete %s [1]", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	expectedOutput := `- 1
+- 3
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestDeleteYamlArrayExpressionCmd(t *testing.T) {
+	content := `- name: fred
+- name: cat
+- name: thing
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete %s (name==cat)", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	expectedOutput := `- name: fred
+- name: thing
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestDeleteYamlMulti(t *testing.T) {
+	content := `apples: great
+---
+- 1
+- 2
+- 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete -d 1 %s [1]", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+
+	expectedOutput := `apples: great
+---
+- 1
+- 3
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestDeleteYamlMultiAllCmd(t *testing.T) {
+	content := `b:
+  c: 3
+apples: great
+---
+apples: great
+something: else
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("delete %s -d * apples", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+---
+something: else`
+	test.AssertResult(t, expectedOutput, strings.Trim(result.Output, "\n "))
+}

cmd/merge_test.go

@@ -0,0 +1,337 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"testing"
+
+	"github.com/mikefarah/yq/v3/test"
+)
+
+func TestMergeCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge ../examples/data1.yaml ../examples/data2.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: simple # just the best
+b: [1, 2]
+c:
+  test: 1
+  toast: leave
+  tell: 1
+  tasty.taco: cool
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeOneFileCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge ../examples/data1.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: simple # just the best
+b: [1, 2]
+c:
+  test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeNoAutoCreateCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge -c=false ../examples/data1.yaml ../examples/data2.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: simple # just the best
+b: [1, 2]
+c:
+  test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeOverwriteCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge -c=false --overwrite ../examples/data1.yaml ../examples/data2.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: other # better than the original
+b: [3, 4]
+c:
+  test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeAppendCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge --autocreate=false --append ../examples/data1.yaml ../examples/data2.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: simple # just the best
+b: [1, 2, 3, 4]
+c:
+  test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeAppendArraysCmd(t *testing.T) {
+	content := `people:
+  - name: Barry
+    age: 21`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	mergeContent := `people:
+  - name: Roger
+    age: 44`
+	mergeFilename := test.WriteTempYamlFile(mergeContent)
+	defer test.RemoveTempYamlFile(mergeFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("merge --append -d* %s %s", filename, mergeFilename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `people:
+- name: Barry
+  age: 21
+- name: Roger
+  age: 44
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeOverwriteAndAppendCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge --autocreate=false --append --overwrite ../examples/data1.yaml ../examples/data2.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: other # better than the original
+b: [1, 2, 3, 4]
+c:
+  test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeArraysCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge --append ../examples/sample_array.yaml ../examples/sample_array_2.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `[1, 2, 3, 4, 5]
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeCmd_Multi(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge -d1 ../examples/multiple_docs_small.yaml ../examples/data1.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: Easy! as one two three
+---
+another:
+  document: here
+a: simple # just the best
+b:
+- 1
+- 2
+c:
+  test: 1
+---
+- 1
+- 2
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeYamlMultiAllCmd(t *testing.T) {
+	content := `b:
+  c: 3
+apples: green
+---
+something: else`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	mergeContent := `apples: red
+something: good`
+	mergeFilename := test.WriteTempYamlFile(mergeContent)
+	defer test.RemoveTempYamlFile(mergeFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("merge -d* %s %s", filename, mergeFilename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+apples: green
+something: good
+---
+something: else
+apples: red
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeSpecialCharacterKeysCmd(t *testing.T) {
+	content := ``
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	mergeContent := `key[bracket]: value
+key.bracket: value
+key"value": value
+key'value': value
+`
+	mergeFilename := test.WriteTempYamlFile(mergeContent)
+	defer test.RemoveTempYamlFile(mergeFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("merge %s %s", filename, mergeFilename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	test.AssertResult(t, mergeContent, result.Output)
+}
+
+func TestMergeYamlMultiAllOverwriteCmd(t *testing.T) {
+	content := `b:
+  c: 3
+apples: green
+---
+something: else`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	mergeContent := `apples: red
+something: good`
+	mergeFilename := test.WriteTempYamlFile(mergeContent)
+	defer test.RemoveTempYamlFile(mergeFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("merge --overwrite -d* %s %s", filename, mergeFilename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+apples: red
+something: good
+---
+something: good
+apples: red
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeYamlNullMapCmd(t *testing.T) {
+	content := `b:`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	mergeContent := `b:
+  thing: a frog
+`
+	mergeFilename := test.WriteTempYamlFile(mergeContent)
+	defer test.RemoveTempYamlFile(mergeFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("merge %s %s", filename, mergeFilename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	test.AssertResult(t, mergeContent, result.Output)
+}
+
+func TestMergeCmd_Error(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide at least 1 yaml file`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestMergeCmd_ErrorUnreadableFile(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge ../examples/data1.yaml fake-unknown")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to unknown file")
+	}
+	var expectedOutput string
+	if runtime.GOOS == "windows" {
+		expectedOutput = `open fake-unknown: The system cannot find the file specified.`
+	} else {
+		expectedOutput = `open fake-unknown: no such file or directory`
+	}
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestMergeCmd_Inplace(t *testing.T) {
+	filename := test.WriteTempYamlFile(test.ReadTempYamlFile("../examples/data1.yaml"))
+	err := os.Chmod(filename, os.FileMode(int(0666)))
+	if err != nil {
+		t.Error(err)
+	}
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("merge -i %s ../examples/data2.yaml", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	info, _ := os.Stat(filename)
+	gotOutput := test.ReadTempYamlFile(filename)
+	expectedOutput := `a: simple # just the best
+b: [1, 2]
+c:
+  test: 1
+  toast: leave
+  tell: 1
+  tasty.taco: cool
+`
+	test.AssertResult(t, expectedOutput, gotOutput)
+	test.AssertResult(t, os.FileMode(int(0666)), info.Mode())
+}
+
+func TestMergeAllowEmptyTargetCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge ../examples/empty.yaml ../examples/data1.yaml")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: simple # just the best
+b:
+- 1
+- 2
+c:
+  test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestMergeAllowEmptyMergeCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "merge ../examples/data1.yaml ../examples/empty.yaml")
+	expectedOutput := `a: simple # just the best
+b: [1, 2]
+c:
+  test: 1
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}

cmd/new.go

@@ -2,6 +2,7 @@ package cmd
 
 import (
 	"github.com/mikefarah/yq/v3/pkg/yqlib"
+	errors "github.com/pkg/errors"
 	"github.com/spf13/cobra"
 )
 
@@ -27,11 +28,17 @@ Note that you can give a create script to perform more sophisticated yaml. This
 	}
 	cmdNew.PersistentFlags().StringVarP(&writeScript, "script", "s", "", "yaml script for creating yaml")
 	cmdNew.PersistentFlags().StringVarP(&customTag, "tag", "t", "", "set yaml tag (e.g. !!int)")
+	cmdNew.PersistentFlags().StringVarP(&customStyle, "style", "", "", "formatting style of the value: single, double, folded, flow, literal, tagged")
 	return cmdNew
 }
 
 func newProperty(cmd *cobra.Command, args []string) error {
-	var updateCommands, updateCommandsError = readUpdateCommands(args, 2, "Must provide <path_to_update> <value>")
+	var badArgsMessage = "Must provide <path_to_update> <value>"
+	if len(args) != 2 {
+		return errors.New(badArgsMessage)
+	}
+
+	var updateCommands, updateCommandsError = readUpdateCommands(args, 2, badArgsMessage)
 	if updateCommandsError != nil {
 		return updateCommandsError
 	}

cmd/new_test.go

@@ -0,0 +1,77 @@
+package cmd
+
+import (
+	"testing"
+
+	"github.com/mikefarah/yq/v3/test"
+)
+
+func TestNewCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "new b.c 3")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestNewArrayCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "new b[0] 3")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+- 3
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestNewCmd_Error(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "new b.c")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide <path_to_update> <value>`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestNewWithTaggedStyleCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "new b.c cat --tag=!!str --style=tagged")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: !!str cat
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestNewWithDoubleQuotedStyleCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "new b.c cat --style=double")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: "cat"
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestNewWithSingleQuotedStyleCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "new b.c cat --style=single")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 'cat'
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}

cmd/prefix_test.go

@@ -0,0 +1,189 @@
+package cmd
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/mikefarah/yq/v3/test"
+)
+
+func TestPrefixCmd(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("prefix %s d", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `d:
+  b:
+    c: 3
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestPrefixCmdArray(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("prefix %s [+].d.[+]", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `- d:
+  - b:
+      c: 3
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestPrefixCmd_MultiLayer(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("prefix %s d.e.f", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `d:
+  e:
+    f:
+      b:
+        c: 3
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestPrefixMultiCmd(t *testing.T) {
+	content := `b:
+  c: 3
+---
+apples: great
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("prefix %s -d 1 d", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+---
+d:
+  apples: great
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+func TestPrefixInvalidDocumentIndexCmd(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("prefix %s -df d", filename))
+	if result.Error == nil {
+		t.Error("Expected command to fail due to invalid path")
+	}
+	expectedOutput := `Document index f is not a integer or *: strconv.ParseInt: parsing "f": invalid syntax`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestPrefixBadDocumentIndexCmd(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("prefix %s -d 1 d", filename))
+	if result.Error == nil {
+		t.Error("Expected command to fail due to invalid path")
+	}
+	expectedOutput := `asked to process document index 1 but there are only 1 document(s)`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+func TestPrefixMultiAllCmd(t *testing.T) {
+	content := `b:
+  c: 3
+---
+apples: great
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("prefix %s -d * d", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `d:
+  b:
+    c: 3
+---
+d:
+  apples: great`
+	test.AssertResult(t, expectedOutput, strings.Trim(result.Output, "\n "))
+}
+
+func TestPrefixCmd_Error(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "prefix")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide <filename> <prefixed_path>`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestPrefixCmd_ErrorUnreadableFile(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "prefix fake-unknown a.b")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to unknown file")
+	}
+	var expectedOutput string
+	if runtime.GOOS == "windows" {
+		expectedOutput = `open fake-unknown: The system cannot find the file specified.`
+	} else {
+		expectedOutput = `open fake-unknown: no such file or directory`
+	}
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestPrefixCmd_Inplace(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("prefix -i %s d", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	gotOutput := test.ReadTempYamlFile(filename)
+	expectedOutput := `d:
+  b:
+    c: 3`
+	test.AssertResult(t, expectedOutput, strings.Trim(gotOutput, "\n "))
+}

cmd/read.go

@@ -29,6 +29,7 @@ yq r -- things.yaml '--key-starting-with-dashes.blah'
 	cmdRead.PersistentFlags().BoolVarP(&printLength, "length", "l", false, "print length of results")
 	cmdRead.PersistentFlags().BoolVarP(&collectIntoArray, "collect", "c", false, "collect results into array")
 	cmdRead.PersistentFlags().BoolVarP(&unwrapScalar, "unwrapScalar", "", true, "unwrap scalar, print the value with no quotes, colors or comments")
+	cmdRead.PersistentFlags().BoolVarP(&stripComments, "stripComments", "", false, "print yaml without any comments")
 	cmdRead.PersistentFlags().BoolVarP(&explodeAnchors, "explodeAnchors", "X", false, "explode anchors")
 	return cmdRead
 }

cmd/utils.go

@@ -114,6 +114,22 @@ func printNode(node *yaml.Node, writer io.Writer) error {
 	return encoder.Encode(node)
 }
 
+func removeComments(matchingNodes []*yqlib.NodeContext) {
+	for _, nodeContext := range matchingNodes {
+		removeCommentOfNode(nodeContext.Node)
+	}
+}
+
+func removeCommentOfNode(node *yaml.Node) {
+	node.HeadComment = ""
+	node.LineComment = ""
+	node.FootComment = ""
+
+	for _, child := range node.Content {
+		removeCommentOfNode(child)
+	}
+}
+
 func setStyle(matchingNodes []*yqlib.NodeContext, style yaml.Style) {
 	for _, nodeContext := range matchingNodes {
 		updateStyleOfNode(nodeContext.Node, style)
@@ -160,6 +176,10 @@ func printResults(matchingNodes []*yqlib.NodeContext, writer io.Writer) error {
 		setStyle(matchingNodes, 0)
 	}
 
+	if stripComments {
+		removeComments(matchingNodes)
+	}
+
 	//always explode anchors when printing json
 	if explodeAnchors || outputToJSON {
 		errorExploding := explode(matchingNodes)
@@ -331,6 +351,7 @@ func updateDoc(inputFile string, updateCommands []yqlib.UpdateCommand, writer io
 func readAndUpdate(stdOut io.Writer, inputFile string, updateData updateDataFn) error {
 	var destination io.Writer
 	var destinationName string
+	var completedSuccessfully = false
 	if writeInplace {
 		info, err := os.Stat(inputFile)
 		if err != nil {
@@ -348,7 +369,9 @@ func readAndUpdate(stdOut io.Writer, inputFile string, updateData updateDataFn)
 		destination = tempFile
 		defer func() {
 			safelyCloseFile(tempFile)
-			safelyRenameFile(tempFile.Name(), inputFile)
+			if completedSuccessfully {
+				safelyRenameFile(tempFile.Name(), inputFile)
+			}
 		}()
 	} else {
 		destination = stdOut
@@ -367,7 +390,9 @@ func readAndUpdate(stdOut io.Writer, inputFile string, updateData updateDataFn)
 		encoder = yqlib.NewYamlEncoder(bufferedWriter, indent, colorsEnabled)
 	}
 
-	return readStream(inputFile, mapYamlDecoder(updateData, encoder))
+	var errorProcessing = readStream(inputFile, mapYamlDecoder(updateData, encoder))
+	completedSuccessfully = errorProcessing == nil
+	return errorProcessing
 }
 
 type updateCommandParsed struct {
@@ -405,15 +430,20 @@ func readUpdateCommands(args []string, expectedArgs int, badArgsMessage string)
 		log.Debug("args %v", args[expectedArgs-2])
 		updateCommands = make([]yqlib.UpdateCommand, 1)
 		updateCommands[0] = yqlib.UpdateCommand{Command: "update", Path: args[expectedArgs-2], Value: value.Content[0], Overwrite: true}
-
-	} else if len(args) < expectedArgs {
-		return nil, errors.New(badArgsMessage)
-	} else {
+	} else if len(args) == expectedArgs {
 		updateCommands = make([]yqlib.UpdateCommand, 1)
 		log.Debug("args %v", args)
 		log.Debug("path %v", args[expectedArgs-2])
 		log.Debug("Value %v", args[expectedArgs-1])
-		updateCommands[0] = yqlib.UpdateCommand{Command: "update", Path: args[expectedArgs-2], Value: valueParser.Parse(args[expectedArgs-1], customTag), Overwrite: true}
+		updateCommands[0] = yqlib.UpdateCommand{Command: "update", Path: args[expectedArgs-2], Value: valueParser.Parse(args[expectedArgs-1], customTag, customStyle), Overwrite: true}
+	} else if len(args) == expectedArgs-1 {
+		// don't update the value
+		updateCommands = make([]yqlib.UpdateCommand, 1)
+		log.Debug("args %v", args)
+		log.Debug("path %v", args[expectedArgs-2])
+		updateCommands[0] = yqlib.UpdateCommand{Command: "update", Path: args[expectedArgs-2], Value: valueParser.Parse("", customTag, customStyle), Overwrite: true, DontUpdateNodeValue: true}
+	} else {
+		return nil, errors.New(badArgsMessage)
 	}
 	return updateCommands, nil
 }

cmd/validate_test.go

@@ -0,0 +1,31 @@
+package cmd
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/mikefarah/yq/v3/test"
+)
+
+func TestValidateCmd(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "validate ../examples/sample.yaml b.c")
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	test.AssertResult(t, "", result.Output)
+}
+
+func TestValidateBadDataCmd(t *testing.T) {
+	content := `[!Whatever]`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("validate %s", filename))
+	if result.Error == nil {
+		t.Error("Expected command to fail")
+	}
+	expectedOutput := `yaml: line 1: did not find expected ',' or ']'`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}

cmd/version.go

@@ -11,7 +11,7 @@ var (
 	GitDescribe string
 
 	// Version is main version number that is being run at the moment.
-	Version = "3.2.1"
+	Version = "3.3.0"
 
 	// 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

cmd/write.go

@@ -46,6 +46,7 @@ format is list of update commands (update or delete) like so:
 	cmdWrite.PersistentFlags().StringVarP(&sourceYamlFile, "from", "f", "", "yaml file for updating yaml (as-is)")
 	cmdWrite.PersistentFlags().StringVarP(&customTag, "tag", "t", "", "set yaml tag (e.g. !!int)")
 	cmdWrite.PersistentFlags().StringVarP(&docIndex, "doc", "d", "0", "process document index number (0 based, * for all documents)")
+	cmdWrite.PersistentFlags().StringVarP(&customStyle, "style", "", "", "formatting style of the value: single, double, folded, flow, literal, tagged")
 	return cmdWrite
 }
 

cmd/write_test.go

@@ -0,0 +1,593 @@
+package cmd
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/mikefarah/yq/v3/test"
+)
+
+func TestWriteCmd(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 7
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteWithTaggedStyleCmd(t *testing.T) {
+	content := `b:
+  c: dog
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c cat --tag=!!str --style=tagged", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: !!str cat
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteWithDoubleQuotedStyleCmd(t *testing.T) {
+	content := `b:
+  c: dog
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c cat --style=double", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: "cat"
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteUpdateStyleOnlyCmd(t *testing.T) {
+	content := `b:
+  c: dog
+  d: things
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.* --style=single", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 'dog'
+  d: 'things'
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteUpdateTagOnlyCmd(t *testing.T) {
+	content := `b:
+  c: true
+  d: false
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.* --tag=!!str", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: "true"
+  d: "false"
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteWithSingleQuotedStyleCmd(t *testing.T) {
+	content := `b:
+  c: dog
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c cat --style=single", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 'cat'
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteWithLiteralStyleCmd(t *testing.T) {
+	content := `b:
+  c: dog
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c cat --style=literal", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: |-
+    cat
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteWithFoldedStyleCmd(t *testing.T) {
+	content := `b:
+  c: dog
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c cat --style=folded", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: >-
+    cat
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteEmptyMultiDocCmd(t *testing.T) {
+	content := `# this is empty
+---
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `c: 7
+
+# this is empty
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteSurroundingEmptyMultiDocCmd(t *testing.T) {
+	content := `---
+# empty
+---
+cat: frog
+---
+
+# empty
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s -d1 c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `
+
+# empty
+---
+cat: frog
+c: 7
+---
+
+
+# empty
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteFromFileCmd(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	source := `kittens: are cute # sure are!`
+	fromFilename := test.WriteTempYamlFile(source)
+	defer test.RemoveTempYamlFile(fromFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c -f %s", filename, fromFilename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c:
+    kittens: are cute # sure are!
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteEmptyCmd(t *testing.T) {
+	content := ``
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 7
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteAutoCreateCmd(t *testing.T) {
+	content := `applications:
+  - name: app
+    env:`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s applications[0].env.hello world", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `applications:
+- name: app
+  env:
+    hello: world
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmdScript(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	updateScript := `- command: update
+  path: b.c
+  value: 7`
+	scriptFilename := test.WriteTempYamlFile(updateScript)
+	defer test.RemoveTempYamlFile(scriptFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write --script %s %s", scriptFilename, filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 7
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmdEmptyScript(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	updateScript := ``
+	scriptFilename := test.WriteTempYamlFile(updateScript)
+	defer test.RemoveTempYamlFile(scriptFilename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write --script %s %s", scriptFilename, filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteMultiCmd(t *testing.T) {
+	content := `b:
+  c: 3
+---
+apples: great
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s -d 1 apples ok", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+---
+apples: ok
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+func TestWriteInvalidDocumentIndexCmd(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s -df apples ok", filename))
+	if result.Error == nil {
+		t.Error("Expected command to fail due to invalid path")
+	}
+	expectedOutput := `Document index f is not a integer or *: strconv.ParseInt: parsing "f": invalid syntax`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestWriteBadDocumentIndexCmd(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s -d 1 apples ok", filename))
+	if result.Error == nil {
+		t.Error("Expected command to fail due to invalid path")
+	}
+	expectedOutput := `asked to process document index 1 but there are only 1 document(s)`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+func TestWriteMultiAllCmd(t *testing.T) {
+	content := `b:
+  c: 3
+---
+apples: great
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s -d * apples ok", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: 3
+apples: ok
+---
+apples: ok`
+	test.AssertResult(t, expectedOutput, strings.Trim(result.Output, "\n "))
+}
+
+func TestWriteCmd_EmptyArray(t *testing.T) {
+	content := `b: 3`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s a []", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b: 3
+a: []
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_Error(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "write")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to missing arg")
+	}
+	expectedOutput := `Must provide <filename> <path_to_update> <value>`
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestWriteCmd_ErrorUnreadableFile(t *testing.T) {
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, "write fake-unknown a.b 3")
+	if result.Error == nil {
+		t.Error("Expected command to fail due to unknown file")
+	}
+	var expectedOutput string
+	if runtime.GOOS == "windows" {
+		expectedOutput = `open fake-unknown: The system cannot find the file specified.`
+	} else {
+		expectedOutput = `open fake-unknown: no such file or directory`
+	}
+	test.AssertResult(t, expectedOutput, result.Error.Error())
+}
+
+func TestWriteCmd_Inplace(t *testing.T) {
+	content := `b:
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write -i %s b.c 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	gotOutput := test.ReadTempYamlFile(filename)
+	expectedOutput := `b:
+  c: 7`
+	test.AssertResult(t, expectedOutput, strings.Trim(gotOutput, "\n "))
+}
+
+func TestWriteCmd_InplaceError(t *testing.T) {
+	content := `b: cat
+  c: 3
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write -i %s b.c 7", filename))
+	if result.Error == nil {
+		t.Error("Expected Error to occur!")
+	}
+	gotOutput := test.ReadTempYamlFile(filename)
+	test.AssertResult(t, content, gotOutput)
+}
+
+func TestWriteCmd_Append(t *testing.T) {
+	content := `b:
+  - foo
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b[+] 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+- foo
+- 7
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_AppendInline(t *testing.T) {
+	content := `b: [foo]`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b[+] 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b: [foo, 7]
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_AppendInlinePretty(t *testing.T) {
+	content := `b: [foo]`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s -P b[+] 7", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+- foo
+- 7
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_AppendEmptyArray(t *testing.T) {
+	content := `a: 2
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b[+] v", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `a: 2
+b:
+- v
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_SplatArray(t *testing.T) {
+	content := `b:
+- c: thing
+- c: another thing
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b[*].c new", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+- c: new
+- c: new
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_SplatMap(t *testing.T) {
+	content := `b:
+  c: thing
+  d: another thing
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.* new", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: new
+  d: new
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}
+
+func TestWriteCmd_SplatMapEmpty(t *testing.T) {
+	content := `b:
+  c: thing
+  d: another thing
+`
+	filename := test.WriteTempYamlFile(content)
+	defer test.RemoveTempYamlFile(filename)
+
+	cmd := getRootCommand()
+	result := test.RunCmd(cmd, fmt.Sprintf("write %s b.c.* new", filename))
+	if result.Error != nil {
+		t.Error(result.Error)
+	}
+	expectedOutput := `b:
+  c: {}
+  d: another thing
+`
+	test.AssertResult(t, expectedOutput, result.Output)
+}

pkg/yqlib/lib.go

@@ -13,10 +13,11 @@ import (
 var log = logging.MustGetLogger("yq")
 
 type UpdateCommand struct {
-	Command   string
-	Path      string
-	Value     *yaml.Node
-	Overwrite bool
+	Command             string
+	Path                string
+	Value               *yaml.Node
+	Overwrite           bool
+	DontUpdateNodeValue bool
 }
 
 func KindString(kind yaml.Kind) string {

pkg/yqlib/update_navigation_strategy.go

@@ -21,7 +21,9 @@ func UpdateNavigationStrategy(updateCommand UpdateCommand, autoCreate bool) Navi
 				DebugNode(node)
 				log.Debug("with")
 				DebugNode(changesToApply)
-				node.Value = changesToApply.Value
+				if !updateCommand.DontUpdateNodeValue {
+					node.Value = changesToApply.Value
+				}
 				node.Tag = changesToApply.Tag
 				node.Kind = changesToApply.Kind
 				node.Style = changesToApply.Style

pkg/yqlib/value_parser.go

@@ -5,7 +5,7 @@ import (
 )
 
 type ValueParser interface {
-	Parse(argument string, customTag string) *yaml.Node
+	Parse(argument string, customTag string, customStyle string) *yaml.Node
 }
 
 type valueParser struct {
@@ -15,9 +15,24 @@ func NewValueParser() ValueParser {
 	return &valueParser{}
 }
 
-func (v *valueParser) Parse(argument string, customTag string) *yaml.Node {
-	if argument == "[]" {
-		return &yaml.Node{Tag: "!!seq", Kind: yaml.SequenceNode}
+func (v *valueParser) Parse(argument string, customTag string, customStyle string) *yaml.Node {
+	var style yaml.Style
+	if customStyle == "tagged" {
+		style = yaml.TaggedStyle
+	} else if customStyle == "double" {
+		style = yaml.DoubleQuotedStyle
+	} else if customStyle == "single" {
+		style = yaml.SingleQuotedStyle
+	} else if customStyle == "literal" {
+		style = yaml.LiteralStyle
+	} else if customStyle == "folded" {
+		style = yaml.FoldedStyle
+	} else if customStyle != "" {
+		log.Error("Unknown style %v, ignoring", customStyle)
 	}
-	return &yaml.Node{Value: argument, Tag: customTag, Kind: yaml.ScalarNode}
+
+	if argument == "[]" {
+		return &yaml.Node{Tag: "!!seq", Kind: yaml.SequenceNode, Style: style}
+	}
+	return &yaml.Node{Value: argument, Tag: customTag, Kind: yaml.ScalarNode, Style: style}
 }

pkg/yqlib/value_parser_test.go

@@ -7,6 +7,25 @@ import (
 	yaml "gopkg.in/yaml.v3"
 )
 
+var parseStyleTests = []struct {
+	customStyle   string
+	expectedStyle yaml.Style
+}{
+	{"", 0},
+	{"tagged", yaml.TaggedStyle},
+	{"double", yaml.DoubleQuotedStyle},
+	{"single", yaml.SingleQuotedStyle},
+	{"folded", yaml.FoldedStyle},
+	{"literal", yaml.LiteralStyle},
+}
+
+func TestValueParserStyleTag(t *testing.T) {
+	for _, tt := range parseStyleTests {
+		actual := NewValueParser().Parse("cat", "", tt.customStyle)
+		test.AssertResultWithContext(t, tt.expectedStyle, actual.Style, tt.customStyle)
+	}
+}
+
 var parseValueTests = []struct {
 	argument        string
 	customTag       string
@@ -20,7 +39,7 @@ var parseValueTests = []struct {
 
 func TestValueParserParse(t *testing.T) {
 	for _, tt := range parseValueTests {
-		actual := NewValueParser().Parse(tt.argument, tt.customTag)
+		actual := NewValueParser().Parse(tt.argument, tt.customTag, "")
 		test.AssertResultWithContext(t, tt.argument, actual.Value, tt.testDescription)
 		test.AssertResultWithContext(t, tt.expectedTag, actual.Tag, tt.testDescription)
 		test.AssertResult(t, yaml.ScalarNode, actual.Kind)
@@ -28,7 +47,7 @@ func TestValueParserParse(t *testing.T) {
 }
 
 func TestValueParserParseEmptyArray(t *testing.T) {
-	actual := NewValueParser().Parse("[]", "")
+	actual := NewValueParser().Parse("[]", "", "")
 	test.AssertResult(t, "!!seq", actual.Tag)
 	test.AssertResult(t, yaml.SequenceNode, actual.Kind)
 }

snap/snapcraft.yaml

@@ -1,5 +1,5 @@
 name: yq
-version: '3.2.1'
+version: '3.3.0'
 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.