GitBook: [#206] deep update example

README.md

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+---
+description: yq is a lightweight and portable command-line YAML processor
+---
+
+# yq
+
+ ![Build](https://github.com/mikefarah/yq/workflows/Build/badge.svg) ![Docker Pulls](https://img.shields.io/docker/pulls/mikefarah/yq.svg) ![Github Releases (by Release)](https://img.shields.io/github/downloads/mikefarah/yq/total.svg) ![Go Report](https://goreportcard.com/badge/github.com/mikefarah/yq)
+
+`yq` is a lightweight and portable command-line YAML processor. `yq` uses [jq](https://github.com/stedolan/jq) like syntax but works with yaml files as well as json. It doesn't yet support everything `jq` does - but it does support the most common operations and functions, and more is being added continuously.
+
+`yq` is written in go - so you can download a dependency free binary for your platform and you are good to go! If you prefer there are a variety of package managers that can be used as well as docker, all listed below.
+
+## v3 users:
+
+Version 4 of `yq` is a major upgrade that now fully supports complex expressions for powerful filtering, slicing and dicing yaml documents. This new version uses syntax very similar to `jq` and works very similarly, so if you've used `jq` before this should be a low learning curve - however it is _quite_ different from previous versions of `yq`. Take a look at the [upgrade guide](upgrading-from-v3.md) for help.
+
+Support for v3 will cease August 2021, until then, critical bug and security fixes will still get applied if required.
+
+## How it works
+
+`yq` works by running`yaml` nodes against a filter expression. The filter expression is made of of operators that pipe into each other. yaml nodes are piped through operators, operators may either return a different set of nodes (e.g. children) or modify the nodes (e.g. update values). See the [operator documentation](https://mikefarah.gitbook.io/yq/operators) for more details and examples.
+
+```
+yq eval 'select(.a == "frog") | .b.c = "dragon"' file.yaml
+```
+
+## Install
+
+#### [Download the latest binary](https://github.com/mikefarah/yq/releases/latest)
+
+### wget
+
+Use wget to download the pre-compiled binaries:
+
+#### Compressed via tar.gz
+
+```bash
+wget https://github.com/mikefarah/yq/releases/download/${VERSION}/${BINARY}.tar.gz -O - |\
+  tar xz && mv ${BINARY} /usr/bin/yq
+```
+
+#### Plain binary
+
+```bash
+wget https://github.com/mikefarah/yq/releases/download/${VERSION}/${BINARY} -O /usr/bin/yq &&\
+    chmod +x /usr/bin/yq
+```
+
+For instance, VERSION=v4.2.0 and BINARY=yq\_linux\_amd64
+
+### Homebrew
+
+[Homebrew](https://brew.sh) is a package manger for MacOS and Linux.
+
+```
+brew install yq
+```
+
+for the (deprecated) v3 version
+
+```
+brew install yq@3
+```
+
+Note that for v3, as it is a versioned brew it will not add the `yq` command to your path automatically. Please follow the instructions given by brew upon installation.
+
+### Snap
+
+Snap can be used on all major Linux distributions.
+
+```
+snap install yq
+```
+
+or, for the (deprecated) v3 version:
+
+```
+snap install yq --channel=v3/stable
+```
+
+**Snap notes**
+
+`yq` installs with [_strict confinement_](https://docs.snapcraft.io/snap-confinement/6233) in snap, this means it doesn't have direct access to root files. To read root files you can:
+
+```
+sudo cat /etc/myfile | yq e '.a.path' -
+```
+
+And to write to a root file you can either use [sponge](https://linux.die.net/man/1/sponge):
+
+```
+sudo cat /etc/myfile | yq e '.a.path = "value"' - | sudo sponge /etc/myfile
+```
+
+or write to a temporary file:
+
+```
+sudo cat /etc/myfile | yq e '.a.path = "value"' | sudo tee /etc/myfile.tmp
+sudo mv /etc/myfile.tmp /etc/myfile
+rm /etc/myfile.tmp
+```
+
+### Docker
+
+**Oneshot use:**
+
+```bash
+docker run --rm -v "${PWD}":/workdir mikefarah/yq <command> [flags] [expression ]FILE...
+```
+
+**Run commands interactively:**
+
+```bash
+docker run --rm -it -v "${PWD}":/workdir --entrypoint sh mikefarah/yq
+```
+
+It can be useful to have a bash function to avoid typing the whole docker command:
+
+```bash
+yq() {
+  docker run --rm -i -v "${PWD}":/workdir mikefarah/yq "$@"
+}
+```
+
+### Go Get
+
+```
+GO111MODULE=on go get github.com/mikefarah/yq
+```
+
+## Community Supported Installation methods
+
+As these are supported by the community :heart: - however, they may be out of date with the officially supported releases.
+
+## Webi
+
+```
+webi yq
+```
+
+See [webi](https://webinstall.dev)  for more infor.
+
+Supported by @adithyasunil26 ([https://github.com/webinstall/webi-installers/tree/master/yq](https://github.com/webinstall/webi-installers/tree/master/yq))
+
+### Chocolatey for Windows:
+
+```
+choco install yq
+```
+
+Supported by @chillum ([https://chocolatey.org/packages/yq](https://chocolatey.org/packages/yq))
+
+### MacPorts:
+
+```
+sudo port selfupdate
+sudo port install yq
+```
+
+Supported by @herbygillot ([https://ports.macports.org/maintainer/github/herbygillot](https://ports.macports.org/maintainer/github/herbygillot))
+
+### Alpine Linux
+
+* Enable edge/community repo by adding `$MIRROR/alpine/edge/community` to `/etc/apk/repositories`
+* Update database index with `apk update`
+* Install yq with `apk add yq`
+
+Supported by Tuan Hoang [https://pkgs.alpinelinux.org/package/edge/community/x86/yq](https://pkgs.alpinelinux.org/package/edge/community/x86/yq)
+
+#### On Ubuntu 16.04 or higher from Debian package:
+
+```bash
+sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys CC86BB64
+sudo add-apt-repository ppa:rmescandon/yq
+sudo apt update
+sudo apt install yq -y
+```
+
+Supported by @rmescandon ([https://launchpad.net/\~rmescandon/+archive/ubuntu/yq](https://launchpad.net/\~rmescandon/+archive/ubuntu/yq))
+
+## Parsing engine and YAML spec support
+
+Under the hood, yq uses [go-yaml v3](https://github.com/go-yaml/yaml/tree/v3) as the yaml parser, which supports [yaml spec 1.2](https://yaml.org/spec/1.2/spec.html). In particular, note that in 1.2 the values 'yes'/'no' are no longer interpreted as booleans, but as strings.

SUMMARY.md

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+# Table of contents
+
+* [yq](README.md)
+* [Upgrading from V3](upgrading-from-v3.md)
+
+## Commands
+
+* [Evaluate](commands/evaluate.md)
+* [Evaluate All](commands/evaluate-all.md)
+* [Shell Completion](commands/shell-completion.md)
+
+***
+
+* [Operators](operators/README.md)
+  * [Add](operators/add.md)
+  * [Alternative (Default value)](operators/alternative-default-value.md)
+  * [Anchor and Alias Operators](operators/anchor-and-alias-operators.md)
+  * [Assign (Update)](operators/assign-update.md)
+  * [Boolean Operators](operators/boolean-operators.md)
+  * [Collect into Array](operators/collect-into-array.md)
+  * [Comment Operators](operators/comment-operators.md)
+  * [Contains](operators/contains.md)
+  * [Create, Collect into Object](operators/create-collect-into-object.md)
+  * [Delete](operators/delete.md)
+  * [Document Index](operators/document-index.md)
+  * [Entries](operators/entries.md)
+  * [Env Variable Operators](operators/env-variable-operators.md)
+  * [Equals](operators/equals.md)
+  * [File Operators](operators/file-operators.md)
+  * [Has](operators/has.md)
+  * [Keys](operators/keys.md)
+  * [Length](operators/length.md)
+  * [Multiply (Merge)](operators/multiply-merge.md)
+  * [Path](operators/path.md)
+  * [Pipe](operators/pipe.md)
+  * [Recursive Descent (Glob)](operators/recursive-descent-glob.md)
+  * [Reduce](operators/reduce.md)
+  * [Select](operators/select.md)
+  * [Sort Keys](operators/sort-keys.md)
+  * [Split into Documents](operators/split-into-documents.md)
+  * [String Operators](operators/string-operators.md)
+  * [Style](operators/style.md)
+  * [Subtract](operators/subtract.md)
+  * [Tag](operators/tag.md)
+  * [Traverse (Read)](operators/traverse-read.md)
+  * [Union](operators/union.md)
+  * [Unique](operators/unique.md)
+  * [Variable Operators](operators/variable-operators.md)
+  * [With](operators/with.md)
+
+## Usage
+
+* [Output format](usage/output-format.md)
+* [Working with Properties](usage/properties.md)
+* [Working with JSON](usage/convert.md)
+* [Front Matter](usage/front-matter.md)
+* [GitHub Action](usage/github-action.md)
+* [Tips, Tricks, Troubleshooting](usage/tips-and-tricks.md)
+
+***
+
+* [Github Page](https://github.com/mikefarah/yq)

commands/evaluate-all.md

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+---
+description: >-
+  Read all documents of all given yaml files into memory, then run the given
+  expression once against the lot.
+---
+
+# Evaluate All
+
+Evaluate All is most useful when needing to run expressions that depend on multiple yaml documents or files. Merge is probably the most common reason why evaluate all would be used. Note that `eval-all` consumes more memory than `evaluate`.
+
+Like `evaluate` you can use `-` to pipe from STDIN.
+
+## Usage
+
+```bash
+yq eval-all [expression] [yaml_file1]... [flags]
+```
+
+Aliases: `eval-all, ea`
+
+## Examples
+
+```bash
+# merges f2.yml into f1.yml (inplace)
+yq eval-all --inplace 'select(fileIndex == 0) * select(fileIndex == 1)' f1.yml f2.yml
+
+# you can merge into a file, piping from STDIN
+cat somefile.yml | yq eval-all --inplace 'select(fileIndex == 0) * select(fileIndex == 1)' f1.yml -
+```
+
+## Flags
+
+```bash
+  -h, --help          help for eval-all
+  -C, --colors        force print with colors
+  -e, --exit-status   set exit status if there are no matches or null or false is returned
+  -I, --indent int    sets indent level for output (default 2)
+  -i, --inplace       update the yaml file inplace of first yaml file given.
+  -M, --no-colors     force print with no colors
+  -N, --no-doc        Don't print document separators (---)
+  -n, --null-input    Don't read input, simply evaluate the expression given. Useful for creating yaml docs from scratch.
+  -j, --tojson        output as json. Set indent to 0 to print json in one line.
+  -v, --verbose       verbose mode
+
+```

commands/evaluate.md

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+---
+description: >-
+  Evaluates the given expression against each yaml document in each file, in
+  sequence
+---
+
+# Evaluate
+
+## Usage: 
+
+```bash
+yq eval [expression] [yaml_file1]... [flags]
+```
+
+Aliases: `eval, e`
+
+Note that you can pass in `-` as a filename to pipe from STDIN.
+
+## Examples:
+
+```bash
+# runs the expression against each file, in series
+yq e '.a.b | length' f1.yml f2.yml 
+
+# '-' will pipe from STDIN
+cat file.yml | yq e '.a.b' f1.yml -  f2.yml
+
+# prints out the file
+yq e sample.yaml 
+cat sample.yml | yq e
+
+# prints a new yaml document
+yq e -n '.a.b.c = "cat"' 
+
+# updates file.yaml directly
+yq e '.a.b = "cool"' -i file.yaml 
+```
+
+
+
+## Flags:
+
+```
+  -h, --help          help for eval
+  -C, --colors        force print with colors
+  -e, --exit-status   set exit status if there are no matches or null or false is returned
+  -I, --indent int    sets indent level for output (default 2)
+  -i, --inplace       update the yaml file inplace of first yaml file given.
+  -M, --no-colors     force print with no colors
+  -N, --no-doc        Don't print document separators (---)
+  -n, --null-input    Don't read input, simply evaluate the expression given. Useful for creating yaml docs from scratch.
+  -j, --tojson        output as json. Set indent to 0 to print json in one line.
+  -v, --verbose       verbose mode
+```

commands/shell-completion.md

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+---
+description: >-
+  Generate a shell completion file for supported shells
+  (bash/fish/zsh/powershell)
+---
+
+# Shell Completion
+
+```bash
+yq shell-completion --variation=zsh
+```
+
+Prints to StdOut a shell completion script for zsh shell.
+
+### Bash (default)
+
+```bash
+source <(yq shell-completion bash)
+```
+
+#### To load completions for each session, execute once:
+
+Linux:
+
+```bash
+yq shell-completion bash > /etc/bash_completion.d/yq 
+```
+
+MacOS:
+
+```bash
+yq shell-completion bash > /usr/local/etc/bash_completion.d/yq
+```
+
+### zsh
+
+If shell completion is not already enabled in your environment you will need to enable it.  You can execute the following once:
+
+```bash
+echo "autoload -U compinit; compinit" >> ~/.zshrc
+```
+
+#### To load completions for each session, execute once:
+
+```bash
+yq shell-completion zsh > "${fpath[1]}/_yq"
+```
+
+You will need to start a new shell for this setup to take effect.
+
+### fish
+
+```bash
+yq shell-completion fish | source
+```
+
+#### To load completions for each session, execute once:
+
+```
+yq shell-completion fish > ~/.config/fish/completions/yq.fish
+```
+
+### PowerShell
+
+```bash
+yq shell-completion powershell
+```
+
+Users need PowerShell version 5.0 or above, which comes with Windows 10 and can be downloaded separately for Windows 7 or 8.1. They can then write the completions to a file and source this file from their PowerShell profile, which is referenced by the $Profile environment variable.

operators/README.md

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+# Operators
+
+## Operators
+
+In `yq` expressions are made up of operators and pipes. A context of nodes is passed through the expression and each operation takes the context as input and returns a new context as output. That output is piped in as input for the next operation in the expression. To begin with, the context is set to the first yaml document of the first yaml file (if processing in sequence using eval).
+
+Lets look at a couple of examples.
+
+### Example with a simple operator
+
+Given a document like:
+
+```yaml
+- [a]
+- "cat"
+```
+
+with an expression:
+
+```
+.[] | length
+```
+
+`yq` will initially set the context as single node of the entire yaml document, an array of two elements.
+
+```yaml
+- [a]
+- "cat"
+```
+
+This gets piped into the splat operator `.[]` which will split out the context into a collection of two nodes `[a]` and `"cat"`. Note that this is _not_ a yaml array.
+
+The `length` operator take no arguments, and will simply return the length of _each_ matching node in the context. So for the context of `[a]` and `"cat"`, it will return a new context of `1` and `3`.
+
+This being the last operation in the expression, the results will be printed out:
+
+```
+1
+3
+```
+
+## Example with an operator that takes arguments.
+
+Given a document like:
+
+```yaml
+a: cat
+b: dog
+```
+
+with an expression:
+
+```
+.a = .b
+```
+
+The `=` operator takes two arguments, a `lhs` expression, which in this case is `.a` and `rhs` expression which is `.b`.
+
+It pipes the current, lets call it 'root' context through the `lhs` expression of `.a` to return the node
+
+```yaml
+cat
+```
+
+Note that this node holds not only its value 'cat', but comments and metadata too, including path and parent information.
+
+The `=` operator then pipes the 'root' context through the `rhs` expression of `.b` to return the node
+
+```yaml
+dog
+```
+
+Both sides have now been evaluated, so now the operator copies across the value from the RHS to the value on the LHS, and it returns the now updated context:
+
+```yaml
+a: dog
+b: dog
+```
+
+## Relative update (e.g. `|=`)
+
+There is another form of the `=` operator which we call the relative form. It's very similar to `=` but with one key difference when evaluating the RHS expression.
+
+In the plain form, we pass in the 'root' level context to the RHS expression. In relative form, we pass in _each result of the LHS_ to the RHS expression. Let's go through an example.
+
+Given a document like:
+
+```yaml
+a: 1
+b: thing
+```
+
+with an expression:
+
+```
+.a |= . + 1
+```
+
+Similar to the `=` operator, `|=` takes two operands, the LHS and RHS.
+
+It pipes the current context (the whole document) through the LHS expression of `.a` to get the node value:
+
+```
+1
+```
+
+Now it pipes _that LHS context_ into the RHS expression `. + 1` (whereas in the `=` plain form it piped the original document context into the RHS) to yield:
+
+```
+2
+```
+
+The assignment operator then copies across the value from the RHS to the value on the LHS, and it returns the now updated 'root' context:
+
+```yaml
+a: 2
+b: thing
+```

operators/add.md

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+# Add
+
+Add behaves differently according to the type of the LHS:
+
+* arrays: concatenate
+* number scalars: arithmetic addition
+* string scalars: concatenate
+
+Use `+=` as append assign for things like increment. Note that `.a += .x` is equivalent to running `.a = .a + .x`.
+
+## Concatenate and assign arrays
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  val: thing
+  b:
+    - cat
+    - dog
+```
+
+then
+
+```bash
+yq eval '.a.b += ["cow"]' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  val: thing
+  b:
+    - cat
+    - dog
+    - cow
+```
+
+## Concatenate arrays
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - 1
+  - 2
+b:
+  - 3
+  - 4
+```
+
+then
+
+```bash
+yq eval '.a + .b' sample.yml
+```
+
+will output
+
+```yaml
+- 1
+- 2
+- 3
+- 4
+```
+
+## Concatenate null to array
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - 1
+  - 2
+```
+
+then
+
+```bash
+yq eval '.a + null' sample.yml
+```
+
+will output
+
+```yaml
+- 1
+- 2
+```
+
+## Add new object to array
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - dog: woof
+```
+
+then
+
+```bash
+yq eval '.a + {"cat": "meow"}' sample.yml
+```
+
+will output
+
+```yaml
+- dog: woof
+- cat: meow
+```
+
+## Add string to array
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - 1
+  - 2
+```
+
+then
+
+```bash
+yq eval '.a + "hello"' sample.yml
+```
+
+will output
+
+```yaml
+- 1
+- 2
+- hello
+```
+
+## Append to array
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - 1
+  - 2
+b:
+  - 3
+  - 4
+```
+
+then
+
+```bash
+yq eval '.a = .a + .b' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  - 1
+  - 2
+  - 3
+  - 4
+b:
+  - 3
+  - 4
+```
+
+## Append another array using +=
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - 1
+  - 2
+b:
+  - 3
+  - 4
+```
+
+then
+
+```bash
+yq eval '.a += .b' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  - 1
+  - 2
+  - 3
+  - 4
+b:
+  - 3
+  - 4
+```
+
+## Relative append
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  a1:
+    b:
+      - cat
+  a2:
+    b:
+      - dog
+  a3: {}
+```
+
+then
+
+```bash
+yq eval '.a[].b += ["mouse"]' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  a1:
+    b:
+      - cat
+      - mouse
+  a2:
+    b:
+      - dog
+      - mouse
+  a3: {b: [mouse]}
+```
+
+## String concatenation
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: meow
+```
+
+then
+
+```bash
+yq eval '.a = .a + .b' sample.yml
+```
+
+will output
+
+```yaml
+a: catmeow
+b: meow
+```
+
+## Number addition - float
+
+If the lhs or rhs are floats then the expression will be calculated with floats.
+
+Given a sample.yml file of:
+
+```yaml
+a: 3
+b: 4.9
+```
+
+then
+
+```bash
+yq eval '.a = .a + .b' sample.yml
+```
+
+will output
+
+```yaml
+a: 7.9
+b: 4.9
+```
+
+## Number addition - int
+
+If both the lhs and rhs are ints then the expression will be calculated with ints.
+
+Given a sample.yml file of:
+
+```yaml
+a: 3
+b: 4
+```
+
+then
+
+```bash
+yq eval '.a = .a + .b' sample.yml
+```
+
+will output
+
+```yaml
+a: 7
+b: 4
+```
+
+## Increment numbers
+
+Given a sample.yml file of:
+
+```yaml
+a: 3
+b: 5
+```
+
+then
+
+```bash
+yq eval '.[] += 1' sample.yml
+```
+
+will output
+
+```yaml
+a: 4
+b: 6
+```
+
+## Add to null
+
+Adding to null simply returns the rhs
+
+Running
+
+```bash
+yq eval --null-input 'null + "cat"'
+```
+
+will output
+
+```yaml
+cat
+```

operators/alternative-default-value.md

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+# Alternative (Default value)
+
+This operator is used to provide alternative (or default) values when a particular expression is either null or false.
+
+## LHS is defined
+
+Given a sample.yml file of:
+
+```yaml
+a: bridge
+```
+
+then
+
+```bash
+yq eval '.a // "hello"' sample.yml
+```
+
+will output
+
+```yaml
+bridge
+```
+
+## LHS is not defined
+
+Given a sample.yml file of:
+
+```yaml
+{}
+```
+
+then
+
+```bash
+yq eval '.a // "hello"' sample.yml
+```
+
+will output
+
+```yaml
+hello
+```
+
+## LHS is null
+
+Given a sample.yml file of:
+
+```yaml
+a: ~
+```
+
+then
+
+```bash
+yq eval '.a // "hello"' sample.yml
+```
+
+will output
+
+```yaml
+hello
+```
+
+## LHS is false
+
+Given a sample.yml file of:
+
+```yaml
+a: false
+```
+
+then
+
+```bash
+yq eval '.a // "hello"' sample.yml
+```
+
+will output
+
+```yaml
+hello
+```
+
+## RHS is an expression
+
+Given a sample.yml file of:
+
+```yaml
+a: false
+b: cat
+```
+
+then
+
+```bash
+yq eval '.a // .b' sample.yml
+```
+
+will output
+
+```yaml
+cat
+```

operators/anchor-and-alias-operators.md

@@ -0,0 +1,421 @@
+# Anchor and Alias Operators
+
+Use the `alias` and `anchor` operators to read and write yaml aliases and anchors. The `explode` operator normalises a yaml file (dereference (or expands) aliases and remove anchor names).
+
+`yq` supports merge aliases (like `<<: *blah`) however this is no longer in the standard yaml spec (1.2) and so `yq` will automatically add the `!!merge` tag to these nodes as it is effectively a custom tag.
+
+## Merge one map
+
+see [https://yaml.org/type/merge.html](https://yaml.org/type/merge.html)
+
+Given a sample.yml file of:
+
+```yaml
+- &CENTER
+  x: 1
+  y: 2
+- &LEFT
+  x: 0
+  y: 2
+- &BIG
+  r: 10
+- &SMALL
+  r: 1
+- !!merge <<: *CENTER
+  r: 10
+```
+
+then
+
+```bash
+yq eval '.[4] | explode(.)' sample.yml
+```
+
+will output
+
+```yaml
+x: 1
+y: 2
+r: 10
+```
+
+## Merge multiple maps
+
+see [https://yaml.org/type/merge.html](https://yaml.org/type/merge.html)
+
+Given a sample.yml file of:
+
+```yaml
+- &CENTER
+  x: 1
+  y: 2
+- &LEFT
+  x: 0
+  y: 2
+- &BIG
+  r: 10
+- &SMALL
+  r: 1
+- !!merge <<:
+    - *CENTER
+    - *BIG
+```
+
+then
+
+```bash
+yq eval '.[4] | explode(.)' sample.yml
+```
+
+will output
+
+```yaml
+r: 10
+x: 1
+y: 2
+```
+
+## Override
+
+see [https://yaml.org/type/merge.html](https://yaml.org/type/merge.html)
+
+Given a sample.yml file of:
+
+```yaml
+- &CENTER
+  x: 1
+  y: 2
+- &LEFT
+  x: 0
+  y: 2
+- &BIG
+  r: 10
+- &SMALL
+  r: 1
+- !!merge <<:
+    - *BIG
+    - *LEFT
+    - *SMALL
+  x: 1
+```
+
+then
+
+```bash
+yq eval '.[4] | explode(.)' sample.yml
+```
+
+will output
+
+```yaml
+r: 10
+x: 1
+y: 2
+```
+
+## Get anchor
+
+Given a sample.yml file of:
+
+```yaml
+a: &billyBob cat
+```
+
+then
+
+```bash
+yq eval '.a | anchor' sample.yml
+```
+
+will output
+
+```yaml
+billyBob
+```
+
+## Set anchor
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval '.a anchor = "foobar"' sample.yml
+```
+
+will output
+
+```yaml
+a: &foobar cat
+```
+
+## Set anchor relatively using assign-update
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: cat
+```
+
+then
+
+```bash
+yq eval '.a anchor |= .b' sample.yml
+```
+
+will output
+
+```yaml
+a: &cat
+  b: cat
+```
+
+## Get alias
+
+Given a sample.yml file of:
+
+```yaml
+b: &billyBob meow
+a: *billyBob
+```
+
+then
+
+```bash
+yq eval '.a | alias' sample.yml
+```
+
+will output
+
+```yaml
+billyBob
+```
+
+## Set alias
+
+Given a sample.yml file of:
+
+```yaml
+b: &meow purr
+a: cat
+```
+
+then
+
+```bash
+yq eval '.a alias = "meow"' sample.yml
+```
+
+will output
+
+```yaml
+b: &meow purr
+a: *meow
+```
+
+## Set alias to blank does nothing
+
+Given a sample.yml file of:
+
+```yaml
+b: &meow purr
+a: cat
+```
+
+then
+
+```bash
+yq eval '.a alias = ""' sample.yml
+```
+
+will output
+
+```yaml
+b: &meow purr
+a: cat
+```
+
+## Set alias relatively using assign-update
+
+Given a sample.yml file of:
+
+```yaml
+b: &meow purr
+a:
+  f: meow
+```
+
+then
+
+```bash
+yq eval '.a alias |= .f' sample.yml
+```
+
+will output
+
+```yaml
+b: &meow purr
+a: *meow
+```
+
+## Explode alias and anchor
+
+Given a sample.yml file of:
+
+```yaml
+f:
+  a: &a cat
+  b: *a
+```
+
+then
+
+```bash
+yq eval 'explode(.f)' sample.yml
+```
+
+will output
+
+```yaml
+f:
+  a: cat
+  b: cat
+```
+
+## Explode with no aliases or anchors
+
+Given a sample.yml file of:
+
+```yaml
+a: mike
+```
+
+then
+
+```bash
+yq eval 'explode(.a)' sample.yml
+```
+
+will output
+
+```yaml
+a: mike
+```
+
+## Explode with alias keys
+
+Given a sample.yml file of:
+
+```yaml
+f:
+  a: &a cat
+  *a: b
+```
+
+then
+
+```bash
+yq eval 'explode(.f)' sample.yml
+```
+
+will output
+
+```yaml
+f:
+  a: cat
+  cat: b
+```
+
+## Explode with merge anchors
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval 'explode(.)' sample.yml
+```
+
+will output
+
+```yaml
+foo:
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar:
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: bar_b
+  thing: foo_thing
+  c: foobarList_c
+  a: foo_a
+foobar:
+  c: foo_c
+  a: foo_a
+  thing: foobar_thing
+```
+
+## Dereference and update a field
+
+\`Use explode with multiply to dereference an object
+
+Given a sample.yml file of:
+
+```yaml
+item_value: &item_value
+  value: true
+thingOne:
+  name: item_1
+  !!merge <<: *item_value
+thingTwo:
+  name: item_2
+  !!merge <<: *item_value
+```
+
+then
+
+```bash
+yq eval '.thingOne |= explode(.) * {"value": false}' sample.yml
+```
+
+will output
+
+```yaml
+item_value: &item_value
+  value: true
+thingOne:
+  name: item_1
+  value: false
+thingTwo:
+  name: item_2
+  !!merge <<: *item_value
+```

operators/assign-update.md

@@ -0,0 +1,274 @@
+# Assign (Update)
+
+## Create yaml file
+
+Running
+
+```bash
+yq eval --null-input '.a.b = "cat" | .x = "frog"'
+```
+
+will output
+
+```yaml
+a:
+  b: cat
+x: frog
+```
+
+## Update node to be the child value
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b:
+    g: foof
+```
+
+then
+
+```bash
+yq eval '.a |= .b' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  g: foof
+```
+
+## Double elements in an array
+
+Given a sample.yml file of:
+
+```yaml
+- 1
+- 2
+- 3
+```
+
+then
+
+```bash
+yq eval '.[] |= . * 2' sample.yml
+```
+
+will output
+
+```yaml
+- 2
+- 4
+- 6
+```
+
+## 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
+a:
+  b: child
+b: sibling
+```
+
+then
+
+```bash
+yq eval '.a = .b' sample.yml
+```
+
+will output
+
+```yaml
+a: sibling
+b: sibling
+```
+
+## Updated multiple paths
+
+Given a sample.yml file of:
+
+```yaml
+a: fieldA
+b: fieldB
+c: fieldC
+```
+
+then
+
+```bash
+yq eval '(.a, .c) = "potatoe"' sample.yml
+```
+
+will output
+
+```yaml
+a: potatoe
+b: fieldB
+c: potatoe
+```
+
+## Update string value
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: apple
+```
+
+then
+
+```bash
+yq eval '.a.b = "frog"' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b: frog
+```
+
+## Update string value via |=
+
+Note there is no difference between `=` and `|=` when the RHS is a scalar
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: apple
+```
+
+then
+
+```bash
+yq eval '.a.b |= "frog"' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b: frog
+```
+
+## Update selected results
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: apple
+  c: cactus
+```
+
+then
+
+```bash
+yq eval '(.a[] | select(. == "apple")) = "frog"' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b: frog
+  c: cactus
+```
+
+## Update array values
+
+Given a sample.yml file of:
+
+```yaml
+- candy
+- apple
+- sandy
+```
+
+then
+
+```bash
+yq eval '(.[] | select(. == "*andy")) = "bogs"' sample.yml
+```
+
+will output
+
+```yaml
+- bogs
+- apple
+- bogs
+```
+
+## Update empty object
+
+Given a sample.yml file of:
+
+```yaml
+{}
+```
+
+then
+
+```bash
+yq eval '.a.b |= "bogs"' sample.yml
+```
+
+will output
+
+```yaml
+{a: {b: bogs}}
+```
+
+## Update empty object and array
+
+Given a sample.yml file of:
+
+```yaml
+{}
+```
+
+then
+
+```bash
+yq eval '.a.b.[0] |= "bogs"' sample.yml
+```
+
+will output
+
+```yaml
+{a: {b: [bogs]}}
+```

operators/boolean-operators.md

@@ -0,0 +1,299 @@
+# Boolean Operators
+
+The `or` and `and` operators take two parameters and return a boolean result.
+
+`not` flips a boolean from true to false, or vice versa.
+
+`any` will return `true` if there are any `true` values in a array sequence, and `all` will return true if _all_ elements in an array are true.
+
+`any_c(condition)` and `all_c(condition)` are like `any` and `all` but they take a condition expression that is used against each element to determine if it's `true`. Note: in `jq` you can simply pass a condition to `any` or `all` and it simply works - `yq` isn't that clever..yet
+
+These are most commonly used with the `select` operator to filter particular nodes.
+
+## `or` example
+
+Running
+
+```bash
+yq eval --null-input 'true or false'
+```
+
+will output
+
+```yaml
+true
+```
+
+## `and` example
+
+Running
+
+```bash
+yq eval --null-input 'true and false'
+```
+
+will output
+
+```yaml
+false
+```
+
+## Matching nodes with select, equals and or
+
+Given a sample.yml file of:
+
+```yaml
+- a: bird
+  b: dog
+- a: frog
+  b: bird
+- a: cat
+  b: fly
+```
+
+then
+
+```bash
+yq eval '[.[] | select(.a == "cat" or .b == "dog")]' sample.yml
+```
+
+will output
+
+```yaml
+- a: bird
+  b: dog
+- a: cat
+  b: fly
+```
+
+## `any` returns true if any boolean in a given array is true
+
+Given a sample.yml file of:
+
+```yaml
+- false
+- true
+```
+
+then
+
+```bash
+yq eval 'any' sample.yml
+```
+
+will output
+
+```yaml
+true
+```
+
+## `any` returns false for an empty array
+
+Given a sample.yml file of:
+
+```yaml
+[]
+```
+
+then
+
+```bash
+yq eval 'any' sample.yml
+```
+
+will output
+
+```yaml
+false
+```
+
+## `any_c` returns true if any element in the array is true for the given condition.
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - rad
+  - awesome
+b:
+  - meh
+  - whatever
+```
+
+then
+
+```bash
+yq eval '.[] |= any_c(. == "awesome")' sample.yml
+```
+
+will output
+
+```yaml
+a: true
+b: false
+```
+
+## `all` returns true if all booleans in a given array are true
+
+Given a sample.yml file of:
+
+```yaml
+- true
+- true
+```
+
+then
+
+```bash
+yq eval 'all' sample.yml
+```
+
+will output
+
+```yaml
+true
+```
+
+## `all` returns true for an empty array
+
+Given a sample.yml file of:
+
+```yaml
+[]
+```
+
+then
+
+```bash
+yq eval 'all' sample.yml
+```
+
+will output
+
+```yaml
+true
+```
+
+## `all_c` returns true if all elements in the array are true for the given condition.
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - rad
+  - awesome
+b:
+  - meh
+  - 12
+```
+
+then
+
+```bash
+yq eval '.[] |= all_c(tag == "!!str")' sample.yml
+```
+
+will output
+
+```yaml
+a: true
+b: false
+```
+
+## Not true is false
+
+Running
+
+```bash
+yq eval --null-input 'true | not'
+```
+
+will output
+
+```yaml
+false
+```
+
+## Not false is true
+
+Running
+
+```bash
+yq eval --null-input 'false | not'
+```
+
+will output
+
+```yaml
+true
+```
+
+## String values considered to be true
+
+Running
+
+```bash
+yq eval --null-input '"cat" | not'
+```
+
+will output
+
+```yaml
+false
+```
+
+## Empty string value considered to be true
+
+Running
+
+```bash
+yq eval --null-input '"" | not'
+```
+
+will output
+
+```yaml
+false
+```
+
+## Numbers are considered to be true
+
+Running
+
+```bash
+yq eval --null-input '1 | not'
+```
+
+will output
+
+```yaml
+false
+```
+
+## Zero is considered to be true
+
+Running
+
+```bash
+yq eval --null-input '0 | not'
+```
+
+will output
+
+```yaml
+false
+```
+
+## Null is considered to be false
+
+Running
+
+```bash
+yq eval --null-input '~ | not'
+```
+
+will output
+
+```yaml
+true
+```

operators/collect-into-array.md

@@ -0,0 +1,53 @@
+# Collect into Array
+
+This creates an array using the expression between the square brackets.
+
+## Collect empty
+
+Running
+
+```bash
+yq eval --null-input '[]'
+```
+
+will output
+
+```yaml
+[]
+```
+
+## Collect single
+
+Running
+
+```bash
+yq eval --null-input '["cat"]'
+```
+
+will output
+
+```yaml
+- cat
+```
+
+## Collect many
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: dog
+```
+
+then
+
+```bash
+yq eval '[.a, .b]' sample.yml
+```
+
+will output
+
+```yaml
+- cat
+- dog
+```

operators/comment-operators.md

@@ -0,0 +1,204 @@
+# Comment Operators
+
+Use these comment operators to set or retrieve comments.
+
+Like the `=` and `|=` assign operators, the same syntax applies when updating comments:
+
+### plain form: `=`
+
+This will assign the LHS nodes comments to the expression on the RHS. The RHS is run against the matching nodes in the pipeline
+
+### relative form: `|=`
+
+Similar to the plain form, however the RHS evaluates against each matching LHS node! This is useful if you want to set the comments as a relative expression of the node, for instance its value or path.
+
+## Set line comment
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval '.a lineComment="single"' sample.yml
+```
+
+will output
+
+```yaml
+a: cat # single
+```
+
+## Use update assign to perform relative updates
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: dog
+```
+
+then
+
+```bash
+yq eval '.. lineComment |= .' sample.yml
+```
+
+will output
+
+```yaml
+a: cat # cat
+b: dog # dog
+```
+
+## Set head comment
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval '. headComment="single"' sample.yml
+```
+
+will output
+
+```yaml
+# single
+
+a: cat
+```
+
+## Set foot comment, using an expression
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval '. footComment=.a' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+
+# cat
+```
+
+## Remove comment
+
+Given a sample.yml file of:
+
+```yaml
+a: cat # comment
+b: dog # leave this
+```
+
+then
+
+```bash
+yq eval '.a lineComment=""' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+b: dog # leave this
+```
+
+## Remove (strip) all comments
+
+Note the use of `...` to ensure key nodes are included.
+
+Given a sample.yml file of:
+
+```yaml
+a: cat # comment
+# great
+b: # key comment
+```
+
+then
+
+```bash
+yq eval '... comments=""' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+b:
+```
+
+## Get line comment
+
+Given a sample.yml file of:
+
+```yaml
+a: cat # meow
+```
+
+then
+
+```bash
+yq eval '.a | lineComment' sample.yml
+```
+
+will output
+
+```yaml
+meow
+```
+
+## Get head comment
+
+Given a sample.yml file of:
+
+```yaml
+a: cat # meow
+```
+
+then
+
+```bash
+yq eval '. | headComment' sample.yml
+```
+
+will output
+
+```yaml
+```
+
+## Get foot comment
+
+Given a sample.yml file of:
+
+```yaml
+a: cat # meow
+```
+
+then
+
+```bash
+yq eval '. | footComment' sample.yml
+```
+
+will output
+
+```yaml
+```

operators/contains.md

@@ -0,0 +1,115 @@
+# Contains
+
+## Array contains array
+
+Array is equal or subset of
+
+Given a sample.yml file of:
+
+```yaml
+- foobar
+- foobaz
+- blarp
+```
+
+then
+
+```bash
+yq eval 'contains(["baz", "bar"])' sample.yml
+```
+
+will output
+
+```yaml
+true
+```
+
+## Object included in array
+
+Given a sample.yml file of:
+
+```yaml
+"foo": 12
+"bar":
+  - 1
+  - 2
+  - "barp": 12
+    "blip": 13
+```
+
+then
+
+```bash
+yq eval 'contains({"bar": [{"barp": 12}]})' sample.yml
+```
+
+will output
+
+```yaml
+true
+```
+
+## Object not included in array
+
+Given a sample.yml file of:
+
+```yaml
+"foo": 12
+"bar":
+  - 1
+  - 2
+  - "barp": 12
+    "blip": 13
+```
+
+then
+
+```bash
+yq eval 'contains({"foo": 12, "bar": [{"barp": 15}]})' sample.yml
+```
+
+will output
+
+```yaml
+false
+```
+
+## String contains substring
+
+Given a sample.yml file of:
+
+```yaml
+foobar
+```
+
+then
+
+```bash
+yq eval 'contains("bar")' sample.yml
+```
+
+will output
+
+```yaml
+true
+```
+
+## String equals string
+
+Given a sample.yml file of:
+
+```yaml
+meow
+```
+
+then
+
+```bash
+yq eval 'contains("meow")' sample.yml
+```
+
+will output
+
+```yaml
+true
+```

operators/create-collect-into-object.md

@@ -0,0 +1,107 @@
+# Create, Collect into Object
+
+This is used to construct objects (or maps). This can be used against existing yaml, or to create fresh yaml documents.
+
+## Collect empty object
+
+Running
+
+```bash
+yq eval --null-input '{}'
+```
+
+will output
+
+```yaml
+{}
+```
+
+## Wrap (prefix) existing object
+
+Given a sample.yml file of:
+
+```yaml
+name: Mike
+```
+
+then
+
+```bash
+yq eval '{"wrap": .}' sample.yml
+```
+
+will output
+
+```yaml
+wrap:
+  name: Mike
+```
+
+## Using splat to create multiple objects
+
+Given a sample.yml file of:
+
+```yaml
+name: Mike
+pets:
+  - cat
+  - dog
+```
+
+then
+
+```bash
+yq eval '{.name: .pets.[]}' sample.yml
+```
+
+will output
+
+```yaml
+Mike: cat
+Mike: dog
+```
+
+## Working with multiple documents
+
+Given a sample.yml file of:
+
+```yaml
+name: Mike
+pets:
+  - cat
+  - dog
+---
+name: Rosey
+pets:
+  - monkey
+  - sheep
+```
+
+then
+
+```bash
+yq eval '{.name: .pets.[]}' sample.yml
+```
+
+will output
+
+```yaml
+Mike: cat
+Mike: dog
+Rosey: monkey
+Rosey: sheep
+```
+
+## Creating yaml from scratch
+
+Running
+
+```bash
+yq eval --null-input '{"wrap": "frog"}'
+```
+
+will output
+
+```yaml
+wrap: frog
+```

operators/delete.md

@@ -0,0 +1,161 @@
+# Delete
+
+Deletes matching entries in maps or arrays.
+
+## Delete entry in map
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: dog
+```
+
+then
+
+```bash
+yq eval 'del(.b)' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+```
+
+## Delete nested entry in map
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  a1: fred
+  a2: frood
+```
+
+then
+
+```bash
+yq eval 'del(.a.a1)' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  a2: frood
+```
+
+## Delete entry in array
+
+Given a sample.yml file of:
+
+```yaml
+- 1
+- 2
+- 3
+```
+
+then
+
+```bash
+yq eval 'del(.[1])' sample.yml
+```
+
+will output
+
+```yaml
+- 1
+- 3
+```
+
+## Delete nested entry in array
+
+Given a sample.yml file of:
+
+```yaml
+- a: cat
+  b: dog
+```
+
+then
+
+```bash
+yq eval 'del(.[0].a)' sample.yml
+```
+
+will output
+
+```yaml
+- b: dog
+```
+
+## Delete no matches
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: dog
+```
+
+then
+
+```bash
+yq eval 'del(.c)' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+b: dog
+```
+
+## Delete matching entries
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: dog
+c: bat
+```
+
+then
+
+```bash
+yq eval 'del( .[] | select(. == "*at") )' sample.yml
+```
+
+will output
+
+```yaml
+b: dog
+```
+
+## Recursively delete matching keys
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  name: frog
+  b:
+    name: blog
+    age: 12
+```
+
+then
+
+```bash
+yq eval 'del(.. | select(has("name")).name)' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b:
+    age: 12
+```

operators/document-index.md

@@ -0,0 +1,120 @@
+# Document Index
+
+Use the `documentIndex` operator (or the `di` shorthand) to select nodes of a particular document.
+
+## Retrieve a document index
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+---
+a: frog
+```
+
+then
+
+```bash
+yq eval '.a | documentIndex' sample.yml
+```
+
+will output
+
+```yaml
+0
+---
+1
+```
+
+## Retrieve a document index, shorthand
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+---
+a: frog
+```
+
+then
+
+```bash
+yq eval '.a | di' sample.yml
+```
+
+will output
+
+```yaml
+0
+---
+1
+```
+
+## Filter by document index
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+---
+a: frog
+```
+
+then
+
+```bash
+yq eval 'select(documentIndex == 1)' sample.yml
+```
+
+will output
+
+```yaml
+a: frog
+```
+
+## Filter by document index shorthand
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+---
+a: frog
+```
+
+then
+
+```bash
+yq eval 'select(di == 1)' sample.yml
+```
+
+will output
+
+```yaml
+a: frog
+```
+
+## Print Document Index with matches
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+---
+a: frog
+```
+
+then
+
+```bash
+yq eval '.a | ({"match": ., "doc": documentIndex})' sample.yml
+```
+
+will output
+
+```yaml
+match: cat
+doc: 0
+match: frog
+doc: 1
+```

operators/entries.md

@@ -0,0 +1,162 @@
+# Entries
+
+Similar to the same named functions in `jq` these functions convert to/from an object and an array of key-value pairs. This is most useful for performing operations on keys of maps.
+
+## to\_entries Map
+
+Given a sample.yml file of:
+
+```yaml
+a: 1
+b: 2
+```
+
+then
+
+```bash
+yq eval 'to_entries' sample.yml
+```
+
+will output
+
+```yaml
+- key: a
+  value: 1
+- key: b
+  value: 2
+```
+
+## to\_entries Array
+
+Given a sample.yml file of:
+
+```yaml
+- a
+- b
+```
+
+then
+
+```bash
+yq eval 'to_entries' sample.yml
+```
+
+will output
+
+```yaml
+- key: 0
+  value: a
+- key: 1
+  value: b
+```
+
+## to\_entries null
+
+Given a sample.yml file of:
+
+```yaml
+null
+```
+
+then
+
+```bash
+yq eval 'to_entries' sample.yml
+```
+
+will output
+
+```yaml
+```
+
+## from\_entries map
+
+Given a sample.yml file of:
+
+```yaml
+a: 1
+b: 2
+```
+
+then
+
+```bash
+yq eval 'to_entries | from_entries' sample.yml
+```
+
+will output
+
+```yaml
+a: 1
+b: 2
+```
+
+## from\_entries with numeric key indexes
+
+from\_entries always creates a map, even for numeric keys
+
+Given a sample.yml file of:
+
+```yaml
+- a
+- b
+```
+
+then
+
+```bash
+yq eval 'to_entries | from_entries' sample.yml
+```
+
+will output
+
+```yaml
+0: a
+1: b
+```
+
+## Use with\_entries to update keys
+
+Given a sample.yml file of:
+
+```yaml
+a: 1
+b: 2
+```
+
+then
+
+```bash
+yq eval 'with_entries(.key |= "KEY_" + .)' sample.yml
+```
+
+will output
+
+```yaml
+KEY_a: 1
+KEY_b: 2
+```
+
+## Use with\_entries to filter the map
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: bird
+c:
+  d: dog
+```
+
+then
+
+```bash
+yq eval 'with_entries(select(.value | has("b")))' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b: bird
+```

operators/env-variable-operators.md

@@ -0,0 +1,108 @@
+# Env Variable Operators
+
+This operator is used to handle environment variables usage in path expressions. While environment variables can, of course, be passed in via your CLI with string interpolation, this often comes with complex quote escaping and can be tricky to write and read. Note that there are two forms, `env` which will parse the environment variable as a yaml (be it a map, array, string, number of boolean) and `strenv` which will always parse the argument as a string.
+
+## Read string environment variable
+
+Running
+
+```bash
+myenv="cat meow" yq eval --null-input '.a = env(myenv)'
+```
+
+will output
+
+```yaml
+a: cat meow
+```
+
+## Read boolean environment variable
+
+Running
+
+```bash
+myenv="true" yq eval --null-input '.a = env(myenv)'
+```
+
+will output
+
+```yaml
+a: true
+```
+
+## Read numeric environment variable
+
+Running
+
+```bash
+myenv="12" yq eval --null-input '.a = env(myenv)'
+```
+
+will output
+
+```yaml
+a: 12
+```
+
+## Read yaml environment variable
+
+Running
+
+```bash
+myenv="{b: fish}" yq eval --null-input '.a = env(myenv)'
+```
+
+will output
+
+```yaml
+a: {b: fish}
+```
+
+## Read boolean environment variable as a string
+
+Running
+
+```bash
+myenv="true" yq eval --null-input '.a = strenv(myenv)'
+```
+
+will output
+
+```yaml
+a: "true"
+```
+
+## Read numeric environment variable as a string
+
+Running
+
+```bash
+myenv="12" yq eval --null-input '.a = strenv(myenv)'
+```
+
+will output
+
+```yaml
+a: "12"
+```
+
+## Dynamic key lookup with environment variable
+
+Given a sample.yml file of:
+
+```yaml
+cat: meow
+dog: woof
+```
+
+then
+
+```bash
+myenv="cat" yq eval '.[env(myenv)]' sample.yml
+```
+
+will output
+
+```yaml
+meow
+```

operators/equals.md

@@ -0,0 +1,163 @@
+# Equals
+
+This is a boolean operator that will return `true` if the LHS is equal to the RHS and `false` otherwise.
+
+```
+.a == .b
+```
+
+It is most often used with the select operator to find particular nodes:
+
+```
+select(.a == .b)
+```
+
+## Match string
+
+Given a sample.yml file of:
+
+```yaml
+- cat
+- goat
+- dog
+```
+
+then
+
+```bash
+yq eval '.[] | (. == "*at")' sample.yml
+```
+
+will output
+
+```yaml
+true
+true
+false
+```
+
+## Don't match string
+
+Given a sample.yml file of:
+
+```yaml
+- cat
+- goat
+- dog
+```
+
+then
+
+```bash
+yq eval '.[] | (. != "*at")' sample.yml
+```
+
+will output
+
+```yaml
+false
+false
+true
+```
+
+## Match number
+
+Given a sample.yml file of:
+
+```yaml
+- 3
+- 4
+- 5
+```
+
+then
+
+```bash
+yq eval '.[] | (. == 4)' sample.yml
+```
+
+will output
+
+```yaml
+false
+true
+false
+```
+
+## Dont match number
+
+Given a sample.yml file of:
+
+```yaml
+- 3
+- 4
+- 5
+```
+
+then
+
+```bash
+yq eval '.[] | (. != 4)' sample.yml
+```
+
+will output
+
+```yaml
+true
+false
+true
+```
+
+## Match nulls
+
+Running
+
+```bash
+yq eval --null-input 'null == ~'
+```
+
+will output
+
+```yaml
+true
+```
+
+## Non exisitant key doesn't equal a value
+
+Given a sample.yml file of:
+
+```yaml
+a: frog
+```
+
+then
+
+```bash
+yq eval 'select(.b != "thing")' sample.yml
+```
+
+will output
+
+```yaml
+a: frog
+```
+
+## Two non existant keys are equal
+
+Given a sample.yml file of:
+
+```yaml
+a: frog
+```
+
+then
+
+```bash
+yq eval 'select(.b == .c)' sample.yml
+```
+
+will output
+
+```yaml
+a: frog
+```

operators/file-operators.md

@@ -0,0 +1,101 @@
+# File Operators
+
+File operators are most often used with merge when needing to merge specific files together. Note that when doing this, you will need to use `eval-all` to ensure all yaml documents are loaded into memory before performing the merge (as opposed to `eval` which runs the expression once per document).
+
+Note that the `fileIndex` operator has a short alias of `fi`.
+
+## Merging files
+
+Note the use of eval-all to ensure all documents are loaded into memory.
+
+```bash
+yq eval-all 'select(fi == 0) * select(filename == "file2.yaml")' file1.yaml file2.yaml
+```
+
+## Get filename
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval 'filename' sample.yml
+```
+
+will output
+
+```yaml
+sample.yml
+```
+
+## Get file index
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval 'fileIndex' sample.yml
+```
+
+will output
+
+```yaml
+0
+```
+
+## Get file indices of multiple documents
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+And another sample another.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval-all 'fileIndex' sample.yml another.yml
+```
+
+will output
+
+```yaml
+0
+---
+1
+```
+
+## Get file index alias
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval 'fi' sample.yml
+```
+
+will output
+
+```yaml
+0
+```

operators/has.md

@@ -0,0 +1,86 @@
+# Has
+
+This is operation that returns true if the key exists in a map (or index in an array), false otherwise.
+
+## Has map key
+
+Given a sample.yml file of:
+
+```yaml
+- a: yes
+- a: ~
+- a:
+- b: nope
+```
+
+then
+
+```bash
+yq eval '.[] | has("a")' sample.yml
+```
+
+will output
+
+```yaml
+true
+true
+true
+false
+```
+
+## Select, checking for existence of deep paths
+
+Simply pipe in parent expressions into `has`
+
+Given a sample.yml file of:
+
+```yaml
+- a:
+    b:
+      c: cat
+- a:
+    b:
+      d: dog
+```
+
+then
+
+```bash
+yq eval '.[] | select(.a.b | has("c"))' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b:
+    c: cat
+```
+
+## Has array index
+
+Given a sample.yml file of:
+
+```yaml
+- []
+- [1]
+- [1, 2]
+- [1, null]
+- [1, 2, 3]
+```
+
+then
+
+```bash
+yq eval '.[] | has(1)' sample.yml
+```
+
+will output
+
+```yaml
+false
+false
+true
+true
+true
+```

operators/keys.md

@@ -0,0 +1,47 @@
+# Keys
+
+Use the `keys` operator to return map keys or array indices.
+
+## Map keys
+
+Given a sample.yml file of:
+
+```yaml
+dog: woof
+cat: meow
+```
+
+then
+
+```bash
+yq eval 'keys' sample.yml
+```
+
+will output
+
+```yaml
+- dog
+- cat
+```
+
+## Array keys
+
+Given a sample.yml file of:
+
+```yaml
+- apple
+- banana
+```
+
+then
+
+```bash
+yq eval 'keys' sample.yml
+```
+
+will output
+
+```yaml
+- 0
+- 1
+```

operators/length.md

@@ -0,0 +1,93 @@
+# Length
+
+Returns the lengths of the nodes. Length is defined according to the type of the node.
+
+## String length
+
+returns length of string
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval '.a | length' sample.yml
+```
+
+will output
+
+```yaml
+3
+```
+
+## null length
+
+Given a sample.yml file of:
+
+```yaml
+a: null
+```
+
+then
+
+```bash
+yq eval '.a | length' sample.yml
+```
+
+will output
+
+```yaml
+0
+```
+
+## Map length
+
+returns number of entries
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+c: dog
+```
+
+then
+
+```bash
+yq eval 'length' sample.yml
+```
+
+will output
+
+```yaml
+2
+```
+
+## Array length
+
+returns number of elements
+
+Given a sample.yml file of:
+
+```yaml
+- 2
+- 4
+- 6
+- 8
+```
+
+then
+
+```bash
+yq eval 'length' sample.yml
+```
+
+will output
+
+```yaml
+4
+```

operators/multiply-merge.md

@@ -0,0 +1,450 @@
+# Multiply (Merge)
+
+Like the multiple operator in jq, depending on the operands, this multiply operator will do different things. Currently numbers, arrays and objects are supported.
+
+## Objects and arrays - merging
+
+Objects are merged deeply matching on matching keys. By default, array values override and are not deeply merged.
+
+Note that when merging objects, this operator returns the merged object (not the parent). This will be clearer in the examples below.
+
+### Merge Flags
+
+You can control how objects are merged by using one or more of the following flags. Multiple flags can be used together, e.g. `.a *+? .b`. See examples below
+
+* `+` to append arrays
+* `?` to only merge existing fields
+* `d` to deeply merge arrays
+
+### Merging files
+
+Note the use of `eval-all` to ensure all documents are loaded into memory.
+
+```bash
+yq eval-all 'select(fileIndex == 0) * select(fileIndex == 1)' file1.yaml file2.yaml
+```
+
+## Multiply integers
+
+Running
+
+```bash
+yq eval --null-input '3 * 4'
+```
+
+will output
+
+```yaml
+12
+```
+
+## Merge objects together, returning merged result only
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  field: me
+  fieldA: cat
+b:
+  field:
+    g: wizz
+  fieldB: dog
+```
+
+then
+
+```bash
+yq eval '.a * .b' sample.yml
+```
+
+will output
+
+```yaml
+field:
+  g: wizz
+fieldA: cat
+fieldB: dog
+```
+
+## Merge objects together, returning parent object
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  field: me
+  fieldA: cat
+b:
+  field:
+    g: wizz
+  fieldB: dog
+```
+
+then
+
+```bash
+yq eval '. * {"a":.b}' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  field:
+    g: wizz
+  fieldA: cat
+  fieldB: dog
+b:
+  field:
+    g: wizz
+  fieldB: dog
+```
+
+## Merge keeps style of LHS
+
+Given a sample.yml file of:
+
+```yaml
+a: {things: great}
+b:
+  also: "me"
+```
+
+then
+
+```bash
+yq eval '. * {"a":.b}' sample.yml
+```
+
+will output
+
+```yaml
+a: {things: great, also: "me"}
+b:
+  also: "me"
+```
+
+## Merge arrays
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - 1
+  - 2
+  - 3
+b:
+  - 3
+  - 4
+  - 5
+```
+
+then
+
+```bash
+yq eval '. * {"a":.b}' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  - 3
+  - 4
+  - 5
+b:
+  - 3
+  - 4
+  - 5
+```
+
+## Merge, only existing fields
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  thing: one
+  cat: frog
+b:
+  missing: two
+  thing: two
+```
+
+then
+
+```bash
+yq eval '.a *? .b' sample.yml
+```
+
+will output
+
+```yaml
+thing: two
+cat: frog
+```
+
+## Merge, appending arrays
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  array:
+    - 1
+    - 2
+    - animal: dog
+  value: coconut
+b:
+  array:
+    - 3
+    - 4
+    - animal: cat
+  value: banana
+```
+
+then
+
+```bash
+yq eval '.a *+ .b' sample.yml
+```
+
+will output
+
+```yaml
+array:
+  - 1
+  - 2
+  - animal: dog
+  - 3
+  - 4
+  - animal: cat
+value: banana
+```
+
+## Merge, only existing fields, appending arrays
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  thing:
+    - 1
+    - 2
+b:
+  thing:
+    - 3
+    - 4
+  another:
+    - 1
+```
+
+then
+
+```bash
+yq eval '.a *?+ .b' sample.yml
+```
+
+will output
+
+```yaml
+thing:
+  - 1
+  - 2
+  - 3
+  - 4
+```
+
+## Merge, deeply merging arrays
+
+Merging arrays deeply means arrays are merge like objects, with indexes as their key. In this case, we merge the first item in the array, and do nothing with the second.
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - name: fred
+    age: 12
+  - name: bob
+    age: 32
+b:
+  - name: fred
+    age: 34
+```
+
+then
+
+```bash
+yq eval '.a *d .b' sample.yml
+```
+
+will output
+
+```yaml
+- name: fred
+  age: 34
+- name: bob
+  age: 32
+```
+
+## Merge arrays of objects together, matching on a key
+
+It's a complex command, the trickyness comes from needing to have the right context in the expressions. First we save the second array into a variable '$two' which lets us reference it later. We then need to update the first array. We will use the relative update (|=) because we need to update relative to the current element of the array in the LHS in the RHS expression. We set the current element of the first array as $cur. Now we multiply (merge) $cur with the matching entry in $two, by passing $two through a select filter.
+
+Given a sample.yml file of:
+
+```yaml
+- a: apple
+  b: appleB
+- a: kiwi
+  b: kiwiB
+- a: banana
+  b: bananaB
+```
+
+And another sample another.yml file of:
+
+```yaml
+- a: banana
+  c: bananaC
+- a: apple
+  b: appleB2
+- a: dingo
+  c: dingoC
+```
+
+then
+
+```bash
+yq eval-all '(select(fi==1) | .[]) as $two | select(fi==0) | .[] |= (. as $cur |  $cur * ($two | select(.a == $cur.a)))' sample.yml another.yml
+```
+
+will output
+
+```yaml
+- a: apple
+  b: appleB2
+- a: kiwi
+  b: kiwiB
+- a: banana
+  b: bananaB
+  c: bananaC
+```
+
+## Merge to prefix an element
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: dog
+```
+
+then
+
+```bash
+yq eval '. * {"a": {"c": .a}}' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  c: cat
+b: dog
+```
+
+## Merge with simple aliases
+
+Given a sample.yml file of:
+
+```yaml
+a: &cat
+  c: frog
+b:
+  f: *cat
+c:
+  g: thongs
+```
+
+then
+
+```bash
+yq eval '.c * .b' sample.yml
+```
+
+will output
+
+```yaml
+g: thongs
+f: *cat
+```
+
+## Merge copies anchor names
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  c: &cat frog
+b:
+  f: *cat
+c:
+  g: thongs
+```
+
+then
+
+```bash
+yq eval '.c * .a' sample.yml
+```
+
+will output
+
+```yaml
+g: thongs
+c: &cat frog
+```
+
+## Merge with merge anchors
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval '.foobar * .foobarList' sample.yml
+```
+
+will output
+
+```yaml
+c: foobarList_c
+<<:
+  - *foo
+  - *bar
+thing: foobar_thing
+b: foobarList_b
+```

operators/path.md

@@ -0,0 +1,123 @@
+# Path
+
+The path operator can be used to get the traversal paths of matching nodes in an expression. The path is returned as an array, which if traversed in order will lead to the matching node.
+
+You can get the key/index of matching nodes by using the `path` operator to return the path array then piping that through `.[-1]` to get the last element of that array, the key.
+
+## Map path
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: cat
+```
+
+then
+
+```bash
+yq eval '.a.b | path' sample.yml
+```
+
+will output
+
+```yaml
+- a
+- b
+```
+
+## Get map key
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: cat
+```
+
+then
+
+```bash
+yq eval '.a.b | path | .[-1]' sample.yml
+```
+
+will output
+
+```yaml
+b
+```
+
+## Array path
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - cat
+  - dog
+```
+
+then
+
+```bash
+yq eval '.a.[] | select(. == "dog") | path' sample.yml
+```
+
+will output
+
+```yaml
+- a
+- 1
+```
+
+## Get array index
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - cat
+  - dog
+```
+
+then
+
+```bash
+yq eval '.a.[] | select(. == "dog") | path | .[-1]' sample.yml
+```
+
+will output
+
+```yaml
+1
+```
+
+## Print path and value
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - cat
+  - dog
+  - frog
+```
+
+then
+
+```bash
+yq eval '.a.[] | select(. == "*og") | [{"path":path, "value":.}]' sample.yml
+```
+
+will output
+
+```yaml
+- path:
+    - a
+    - 1
+  value: dog
+- path:
+    - a
+    - 2
+  value: frog
+```

operators/pipe.md

@@ -0,0 +1,48 @@
+# Pipe
+
+Pipe the results of an expression into another. Like the bash operator.
+
+## Simple Pipe
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: cat
+```
+
+then
+
+```bash
+yq eval '.a | .b' sample.yml
+```
+
+will output
+
+```yaml
+cat
+```
+
+## Multiple updates
+
+Given a sample.yml file of:
+
+```yaml
+a: cow
+b: sheep
+c: same
+```
+
+then
+
+```bash
+yq eval '.a = "cat" | .b = "dog"' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+b: dog
+c: same
+```

operators/recursive-descent-glob.md

@@ -0,0 +1,194 @@
+# Recursive Descent (Glob)
+
+This operator recursively matches (or globs) all children nodes given of a particular element, including that node itself. This is most often used to apply a filter recursively against all matches. It can be used in either the
+
+## match values form `..`
+
+This will, like the `jq` equivalent, recursively match all _value_ nodes. Use it to find/manipulate particular values.
+
+For instance to set the `style` of all _value_ nodes in a yaml doc, excluding map keys:
+
+```bash
+yq eval '.. style= "flow"' file.yaml
+```
+
+## match values and map keys form `...`
+
+The also includes map keys in the results set. This is particularly useful in YAML as unlike JSON, map keys can have their own styling, tags and use anchors and aliases.
+
+For instance to set the `style` of all nodes in a yaml doc, including the map keys:
+
+```bash
+yq eval '... style= "flow"' file.yaml
+```
+
+## Recurse map (values only)
+
+Given a sample.yml file of:
+
+```yaml
+a: frog
+```
+
+then
+
+```bash
+yq eval '..' sample.yml
+```
+
+will output
+
+```yaml
+a: frog
+frog
+```
+
+## Recursively find nodes with keys
+
+Note that this example has wrapped the expression in `[]` to show that there are two matches returned. You do not have to wrap in `[]` in your path expression.
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  name: frog
+  b:
+    name: blog
+    age: 12
+```
+
+then
+
+```bash
+yq eval '[.. | select(has("name"))]' sample.yml
+```
+
+will output
+
+```yaml
+- name: frog
+  b:
+    name: blog
+    age: 12
+- name: blog
+  age: 12
+```
+
+## Recursively find nodes with values
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  nameA: frog
+  b:
+    nameB: frog
+    age: 12
+```
+
+then
+
+```bash
+yq eval '.. | select(. == "frog")' sample.yml
+```
+
+will output
+
+```yaml
+frog
+frog
+```
+
+## Recurse map (values and keys)
+
+Note that the map key appears in the results
+
+Given a sample.yml file of:
+
+```yaml
+a: frog
+```
+
+then
+
+```bash
+yq eval '...' sample.yml
+```
+
+will output
+
+```yaml
+a: frog
+a
+frog
+```
+
+## Aliases are not traversed
+
+Given a sample.yml file of:
+
+```yaml
+a: &cat
+  c: frog
+b: *cat
+```
+
+then
+
+```bash
+yq eval '[..]' sample.yml
+```
+
+will output
+
+```yaml
+- a: &cat
+    c: frog
+  b: *cat
+- &cat
+  c: frog
+- frog
+- *cat
+```
+
+## Merge docs are not traversed
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval '.foobar | [..]' sample.yml
+```
+
+will output
+
+```yaml
+- c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+- foobar_c
+- *foo
+- foobar_thing
+```

operators/reduce.md

@@ -0,0 +1,97 @@
+# Reduce
+
+Reduce is a powerful way to process a collection of data into a new form.
+
+```
+<exp> as $<name> ireduce (<init>; <block>)
+```
+
+e.g.
+
+```
+.[] as $item ireduce (0; . + $item)
+```
+
+On the LHS we are configuring the collection of items that will be reduced `<exp>` as well as what each element will be called `$<name>`. Note that the array has been splatted into its individual elements.
+
+On the RHS there is `<init>`, the starting value of the accumulator and `<block>`, the expression that will update the accumulator for each element in the collection. Note that within the block expression, `.` will evaluate to the current value of the accumulator.
+
+## yq vs jq syntax
+
+Reduce syntax in `yq` is a little different from `jq` - as `yq` (currently) isn't as sophisticated as `jq` and its only supports infix notation (e.g. a + b, where the operator is in the middle of the two parameters) - where as `jq` uses a mix of infix notation with _prefix_ notation (e.g. `reduce a b` is like writing `+ a b`).
+
+To that end, the reduce operator is called `ireduce` for backwards compatability if a `jq` like prefix version of `reduce` is ever added.
+
+## Sum numbers
+
+Given a sample.yml file of:
+
+```yaml
+- 10
+- 2
+- 5
+- 3
+```
+
+then
+
+```bash
+yq eval '.[] as $item ireduce (0; . + $item)' sample.yml
+```
+
+will output
+
+```yaml
+20
+```
+
+## Merge all yaml files together
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+And another sample another.yml file of:
+
+```yaml
+b: dog
+```
+
+then
+
+```bash
+yq eval-all '. as $item ireduce ({}; . * $item )' sample.yml another.yml
+```
+
+will output
+
+```yaml
+a: cat
+b: dog
+```
+
+## Convert an array to an object
+
+Given a sample.yml file of:
+
+```yaml
+- name: Cathy
+  has: apples
+- name: Bob
+  has: bananas
+```
+
+then
+
+```bash
+yq eval '.[] as $item ireduce ({}; .[$item | .name] = ($item | .has) )' sample.yml
+```
+
+will output
+
+```yaml
+Cathy: apples
+Bob: bananas
+```

operators/select.md

@@ -0,0 +1,52 @@
+# Select
+
+Select is used to filter arrays and maps by a boolean expression.
+
+## Select elements from array
+
+Given a sample.yml file of:
+
+```yaml
+- cat
+- goat
+- dog
+```
+
+then
+
+```bash
+yq eval '.[] | select(. == "*at")' sample.yml
+```
+
+will output
+
+```yaml
+cat
+goat
+```
+
+## Select and update matching values in map
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  things: cat
+  bob: goat
+  horse: dog
+```
+
+then
+
+```bash
+yq eval '(.a.[] | select(. == "*at")) |= "rabbit"' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  things: rabbit
+  bob: rabbit
+  horse: dog
+```

operators/sort-keys.md

@@ -0,0 +1,81 @@
+# Sort Keys
+
+The Sort Keys operator sorts maps by their keys (based on their string value). This operator does not do anything to arrays or scalars (so you can easily recursively apply it to all maps).
+
+Sort is particularly useful for diffing two different yaml documents:
+
+```bash
+yq eval -i 'sortKeys(..)' file1.yml
+yq eval -i 'sortKeys(..)' file2.yml
+diff file1.yml file2.yml
+```
+
+## Sort keys of map
+
+Given a sample.yml file of:
+
+```yaml
+c: frog
+a: blah
+b: bing
+```
+
+then
+
+```bash
+yq eval 'sortKeys(.)' sample.yml
+```
+
+will output
+
+```yaml
+a: blah
+b: bing
+c: frog
+```
+
+## Sort keys recursively
+
+Note the array elements are left unsorted, but maps inside arrays are sorted
+
+Given a sample.yml file of:
+
+```yaml
+bParent:
+  c: dog
+  array:
+    - 3
+    - 1
+    - 2
+aParent:
+  z: donkey
+  x:
+    - c: yum
+      b: delish
+    - b: ew
+      a: apple
+```
+
+then
+
+```bash
+yq eval 'sortKeys(..)' sample.yml
+```
+
+will output
+
+```yaml
+aParent:
+  x:
+    - b: delish
+      c: yum
+    - a: apple
+      b: ew
+  z: donkey
+bParent:
+  array:
+    - 3
+    - 1
+    - 2
+  c: dog
+```

operators/split-into-documents.md

@@ -0,0 +1,39 @@
+# Split into Documents
+
+This operator splits all matches into separate documents
+
+## Split empty
+
+Running
+
+```bash
+yq eval --null-input 'splitDoc'
+```
+
+will output
+
+```yaml
+```
+
+## Split array
+
+Given a sample.yml file of:
+
+```yaml
+- a: cat
+- b: dog
+```
+
+then
+
+```bash
+yq eval '.[] | splitDoc' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+---
+b: dog
+```

operators/string-operators.md

@@ -0,0 +1,376 @@
+# String Operators
+
+## String Operators
+
+### RegEx
+
+This uses golangs native regex functions under the hood - See [https://github.com/google/re2/wiki/Syntax](https://github.com/google/re2/wiki/Syntax) for the supported syntax.
+
+## String blocks, bash and newlines
+
+Bash is notorious for chomping on precious trailing newline characters, making it tricky to set strings with newlines properly. In particular, the `$( exp )` _will trim trailing newlines_.
+
+For instance to get this yaml:
+
+```
+a: |
+  cat
+```
+
+Using `$( exp )` wont work, as it will trim the trailing new line.
+
+```
+m=$(echo "cat\n") yq e -n '.a = strenv(m)'
+a: cat
+```
+
+However, using printf works:
+
+```
+printf -v m "cat\n" ; m="$m" yq e -n '.a = strenv(m)'
+a: |
+  cat
+```
+
+As well as having multiline expressions:
+
+```
+m="cat
+"  yq e -n '.a = strenv(m)'
+a: |
+  cat
+```
+
+Similarly, if you're trying to set the content from a file, and want a trailing new line:
+
+```
+IFS= read -rd '' output < <(cat my_file)
+output=$output ./yq e '.data.values = strenv(output)' first.yml
+```
+
+### Join strings
+
+Given a sample.yml file of:
+
+```yaml
+- cat
+- meow
+- 1
+- null
+- true
+```
+
+then
+
+```bash
+yq eval 'join("; ")' sample.yml
+```
+
+will output
+
+```yaml
+cat; meow; 1; ; true
+```
+
+### Match string
+
+Given a sample.yml file of:
+
+```yaml
+foo bar foo
+```
+
+then
+
+```bash
+yq eval 'match("foo")' sample.yml
+```
+
+will output
+
+```yaml
+string: foo
+offset: 0
+length: 3
+captures: []
+```
+
+### Match string, case insensitive
+
+Given a sample.yml file of:
+
+```yaml
+foo bar FOO
+```
+
+then
+
+```bash
+yq eval '[match("(?i)foo"; "g")]' sample.yml
+```
+
+will output
+
+```yaml
+- string: foo
+  offset: 0
+  length: 3
+  captures: []
+- string: FOO
+  offset: 8
+  length: 3
+  captures: []
+```
+
+### Match with capture groups
+
+Given a sample.yml file of:
+
+```yaml
+abc abc
+```
+
+then
+
+```bash
+yq eval '[match("(abc)+"; "g")]' sample.yml
+```
+
+will output
+
+```yaml
+- string: abc
+  offset: 0
+  length: 3
+  captures:
+    - string: abc
+      offset: 0
+      length: 3
+- string: abc
+  offset: 4
+  length: 3
+  captures:
+    - string: abc
+      offset: 4
+      length: 3
+```
+
+### Match with named capture groups
+
+Given a sample.yml file of:
+
+```yaml
+foo bar foo foo  foo
+```
+
+then
+
+```bash
+yq eval '[match("foo (?P<bar123>bar)? foo"; "g")]' sample.yml
+```
+
+will output
+
+```yaml
+- string: foo bar foo
+  offset: 0
+  length: 11
+  captures:
+    - string: bar
+      offset: 4
+      length: 3
+      name: bar123
+- string: foo  foo
+  offset: 12
+  length: 8
+  captures:
+    - string: null
+      offset: -1
+      length: 0
+      name: bar123
+```
+
+### Capture named groups into a map
+
+Given a sample.yml file of:
+
+```yaml
+xyzzy-14
+```
+
+then
+
+```bash
+yq eval 'capture("(?P<a>[a-z]+)-(?P<n>[0-9]+)")' sample.yml
+```
+
+will output
+
+```yaml
+a: xyzzy
+n: "14"
+```
+
+### Match without global flag
+
+Given a sample.yml file of:
+
+```yaml
+cat cat
+```
+
+then
+
+```bash
+yq eval 'match("cat")' sample.yml
+```
+
+will output
+
+```yaml
+string: cat
+offset: 0
+length: 3
+captures: []
+```
+
+### Match with global flag
+
+Given a sample.yml file of:
+
+```yaml
+cat cat
+```
+
+then
+
+```bash
+yq eval '[match("cat"; "g")]' sample.yml
+```
+
+will output
+
+```yaml
+- string: cat
+  offset: 0
+  length: 3
+  captures: []
+- string: cat
+  offset: 4
+  length: 3
+  captures: []
+```
+
+### Test using regex
+
+Like jq'q equivalant, this works like match but only returns true/false instead of full match details
+
+Given a sample.yml file of:
+
+```yaml
+- cat
+- dog
+```
+
+then
+
+```bash
+yq eval '.[] | test("at")' sample.yml
+```
+
+will output
+
+```yaml
+true
+false
+```
+
+### Substitute / Replace string
+
+This uses golang regex, described [here](https://github.com/google/re2/wiki/Syntax) Note the use of `|=` to run in context of the current string value.
+
+Given a sample.yml file of:
+
+```yaml
+a: dogs are great
+```
+
+then
+
+```bash
+yq eval '.a |= sub("dogs", "cats")' sample.yml
+```
+
+will output
+
+```yaml
+a: cats are great
+```
+
+### Substitute / Replace string with regex
+
+This uses golang regex, described [here](https://github.com/google/re2/wiki/Syntax) Note the use of `|=` to run in context of the current string value.
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: heat
+```
+
+then
+
+```bash
+yq eval '.[] |= sub("(a)", "${1}r")' sample.yml
+```
+
+will output
+
+```yaml
+a: cart
+b: heart
+```
+
+### Split strings
+
+Given a sample.yml file of:
+
+```yaml
+cat; meow; 1; ; true
+```
+
+then
+
+```bash
+yq eval 'split("; ")' sample.yml
+```
+
+will output
+
+```yaml
+- cat
+- meow
+- "1"
+- ""
+- "true"
+```
+
+### Split strings one match
+
+Given a sample.yml file of:
+
+```yaml
+word
+```
+
+then
+
+```bash
+yq eval 'split("; ")' sample.yml
+```
+
+will output
+
+```yaml
+- word
+```

operators/style.md

@@ -0,0 +1,311 @@
+# Style
+
+The style operator can be used to get or set the style of nodes (e.g. string style, yaml style)
+
+## Update and set style of a particular node (simple)
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: thing
+  c: something
+```
+
+then
+
+```bash
+yq eval '.a.b = "new" | .a.b style="double"' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b: "new"
+  c: something
+```
+
+## Update and set style of a particular node using path variables
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: thing
+  c: something
+```
+
+then
+
+```bash
+yq eval 'with(.a.b ; . = "new" | . style="double")' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b: "new"
+  c: something
+```
+
+## Set tagged style
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+then
+
+```bash
+yq eval '.. style="tagged"' sample.yml
+```
+
+will output
+
+```yaml
+!!map
+a: !!str cat
+b: !!int 5
+c: !!float 3.2
+e: !!bool true
+```
+
+## Set double quote style
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+then
+
+```bash
+yq eval '.. style="double"' sample.yml
+```
+
+will output
+
+```yaml
+a: "cat"
+b: "5"
+c: "3.2"
+e: "true"
+```
+
+## Set double quote style on map keys too
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+then
+
+```bash
+yq eval '... style="double"' sample.yml
+```
+
+will output
+
+```yaml
+"a": "cat"
+"b": "5"
+"c": "3.2"
+"e": "true"
+```
+
+## Set single quote style
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+then
+
+```bash
+yq eval '.. style="single"' sample.yml
+```
+
+will output
+
+```yaml
+a: 'cat'
+b: '5'
+c: '3.2'
+e: 'true'
+```
+
+## Set literal quote style
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+then
+
+```bash
+yq eval '.. style="literal"' sample.yml
+```
+
+will output
+
+```yaml
+a: |-
+  cat
+b: |-
+  5
+c: |-
+  3.2
+e: |-
+  true
+```
+
+## Set folded quote style
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+then
+
+```bash
+yq eval '.. style="folded"' sample.yml
+```
+
+will output
+
+```yaml
+a: >-
+  cat
+b: >-
+  5
+c: >-
+  3.2
+e: >-
+  true
+```
+
+## Set flow quote style
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+then
+
+```bash
+yq eval '.. style="flow"' sample.yml
+```
+
+will output
+
+```yaml
+{a: cat, b: 5, c: 3.2, e: true}
+```
+
+## Reset style - or pretty print
+
+Set empty (default) quote style, note the usage of `...` to match keys too. Note that there is a `--prettyPrint/-P` short flag for this.
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+"b": 5
+'c': 3.2
+"e": true
+```
+
+then
+
+```bash
+yq eval '... style=""' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+## Set style relatively with assign-update
+
+Given a sample.yml file of:
+
+```yaml
+a: single
+b: double
+```
+
+then
+
+```bash
+yq eval '.[] style |= .' sample.yml
+```
+
+will output
+
+```yaml
+a: 'single'
+b: "double"
+```
+
+## Read style
+
+Given a sample.yml file of:
+
+```yaml
+{a: "cat", b: 'thing'}
+```
+
+then
+
+```bash
+yq eval '.. | style' sample.yml
+```
+
+will output
+
+```yaml
+flow
+double
+single
+```

operators/subtract.md

@@ -0,0 +1,148 @@
+# Subtract
+
+## Array subtraction
+
+Running
+
+```bash
+yq eval --null-input '[1,2] - [2,3]'
+```
+
+will output
+
+```yaml
+- 1
+```
+
+## Array subtraction with nested array
+
+Running
+
+```bash
+yq eval --null-input '[[1], 1, 2] - [[1], 3]'
+```
+
+will output
+
+```yaml
+- 1
+- 2
+```
+
+## Array subtraction with nested object
+
+Note that order of the keys does not matter
+
+Given a sample.yml file of:
+
+```yaml
+- a: b
+  c: d
+- a: b
+```
+
+then
+
+```bash
+yq eval '. - [{"c": "d", "a": "b"}]' sample.yml
+```
+
+will output
+
+```yaml
+- a: b
+```
+
+## Number subtraction - float
+
+If the lhs or rhs are floats then the expression will be calculated with floats.
+
+Given a sample.yml file of:
+
+```yaml
+a: 3
+b: 4.5
+```
+
+then
+
+```bash
+yq eval '.a = .a - .b' sample.yml
+```
+
+will output
+
+```yaml
+a: -1.5
+b: 4.5
+```
+
+## Number subtraction - float
+
+If the lhs or rhs are floats then the expression will be calculated with floats.
+
+Given a sample.yml file of:
+
+```yaml
+a: 3
+b: 4.5
+```
+
+then
+
+```bash
+yq eval '.a = .a - .b' sample.yml
+```
+
+will output
+
+```yaml
+a: -1.5
+b: 4.5
+```
+
+## Number subtraction - int
+
+If both the lhs and rhs are ints then the expression will be calculated with ints.
+
+Given a sample.yml file of:
+
+```yaml
+a: 3
+b: 4
+```
+
+then
+
+```bash
+yq eval '.a = .a - .b' sample.yml
+```
+
+will output
+
+```yaml
+a: -1
+b: 4
+```
+
+## Decrement numbers
+
+Given a sample.yml file of:
+
+```yaml
+a: 3
+b: 5
+```
+
+then
+
+```bash
+yq eval '.[] -= 1' sample.yml
+```
+
+will output
+
+```yaml
+a: 2
+b: 4
+```

operators/tag.md

@@ -0,0 +1,78 @@
+# Tag
+
+The tag operator can be used to get or set the tag of nodes (e.g. `!!str`, `!!int`, `!!bool`).
+
+## Get tag
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+f: []
+```
+
+then
+
+```bash
+yq eval '.. | tag' sample.yml
+```
+
+will output
+
+```yaml
+!!map
+!!str
+!!int
+!!float
+!!bool
+!!seq
+```
+
+## Set custom tag
+
+Given a sample.yml file of:
+
+```yaml
+a: str
+```
+
+then
+
+```bash
+yq eval '.a tag = "!!mikefarah"' sample.yml
+```
+
+will output
+
+```yaml
+a: !!mikefarah str
+```
+
+## Find numbers and convert them to strings
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+b: 5
+c: 3.2
+e: true
+```
+
+then
+
+```bash
+yq eval '(.. | select(tag == "!!int")) tag= "!!str"' sample.yml
+```
+
+will output
+
+```yaml
+a: cat
+b: "5"
+c: 3.2
+e: true
+```

operators/traverse-read.md

@@ -0,0 +1,628 @@
+# Traverse (Read)
+
+This is the simplest (and perhaps most used) operator, it is used to navigate deeply into yaml structures.
+
+## Simple map navigation
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: apple
+```
+
+then
+
+```bash
+yq eval '.a' sample.yml
+```
+
+will output
+
+```yaml
+b: apple
+```
+
+## Splat
+
+Often used to pipe children into other operators
+
+Given a sample.yml file of:
+
+```yaml
+- b: apple
+- c: banana
+```
+
+then
+
+```bash
+yq eval '.[]' sample.yml
+```
+
+will output
+
+```yaml
+b: apple
+c: banana
+```
+
+## Optional Splat
+
+Just like splat, but won't error if you run it against scalars
+
+Given a sample.yml file of:
+
+```yaml
+cat
+```
+
+then
+
+```bash
+yq eval '.[]' sample.yml
+```
+
+will output
+
+```yaml
+```
+
+## Special characters
+
+Use quotes with brackets around path elements with special characters
+
+Given a sample.yml file of:
+
+```yaml
+"{}": frog
+```
+
+then
+
+```bash
+yq eval '.["{}"]' sample.yml
+```
+
+will output
+
+```yaml
+frog
+```
+
+## Nested special characters
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  "key.withdots":
+    "another.key": apple
+```
+
+then
+
+```bash
+yq eval '.a["key.withdots"]["another.key"]' sample.yml
+```
+
+will output
+
+```yaml
+apple
+```
+
+## Keys with spaces
+
+Use quotes with brackets around path elements with special characters
+
+Given a sample.yml file of:
+
+```yaml
+"red rabbit": frog
+```
+
+then
+
+```bash
+yq eval '.["red rabbit"]' sample.yml
+```
+
+will output
+
+```yaml
+frog
+```
+
+## Dynamic keys
+
+Expressions within \[] can be used to dynamically lookup / calculate keys
+
+Given a sample.yml file of:
+
+```yaml
+b: apple
+apple: crispy yum
+banana: soft yum
+```
+
+then
+
+```bash
+yq eval '.[.b]' sample.yml
+```
+
+will output
+
+```yaml
+crispy yum
+```
+
+## Children don't exist
+
+Nodes are added dynamically while traversing
+
+Given a sample.yml file of:
+
+```yaml
+c: banana
+```
+
+then
+
+```bash
+yq eval '.a.b' sample.yml
+```
+
+will output
+
+```yaml
+null
+```
+
+## Optional identifier
+
+Like jq, does not output an error when the yaml is not an array or object as expected
+
+Given a sample.yml file of:
+
+```yaml
+- 1
+- 2
+- 3
+```
+
+then
+
+```bash
+yq eval '.a?' sample.yml
+```
+
+will output
+
+```yaml
+```
+
+## Wildcard matching
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  cat: apple
+  mad: things
+```
+
+then
+
+```bash
+yq eval '.a."*a*"' sample.yml
+```
+
+will output
+
+```yaml
+apple
+things
+```
+
+## Aliases
+
+Given a sample.yml file of:
+
+```yaml
+a: &cat
+  c: frog
+b: *cat
+```
+
+then
+
+```bash
+yq eval '.b' sample.yml
+```
+
+will output
+
+```yaml
+*cat
+```
+
+## Traversing aliases with splat
+
+Given a sample.yml file of:
+
+```yaml
+a: &cat
+  c: frog
+b: *cat
+```
+
+then
+
+```bash
+yq eval '.b[]' sample.yml
+```
+
+will output
+
+```yaml
+frog
+```
+
+## Traversing aliases explicitly
+
+Given a sample.yml file of:
+
+```yaml
+a: &cat
+  c: frog
+b: *cat
+```
+
+then
+
+```bash
+yq eval '.b.c' sample.yml
+```
+
+will output
+
+```yaml
+frog
+```
+
+## Traversing arrays by index
+
+Given a sample.yml file of:
+
+```yaml
+- 1
+- 2
+- 3
+```
+
+then
+
+```bash
+yq eval '.[0]' sample.yml
+```
+
+will output
+
+```yaml
+1
+```
+
+## Traversing nested arrays by index
+
+Given a sample.yml file of:
+
+```yaml
+[[], [cat]]
+```
+
+then
+
+```bash
+yq eval '.[1][0]' sample.yml
+```
+
+will output
+
+```yaml
+cat
+```
+
+## Maps with numeric keys
+
+Given a sample.yml file of:
+
+```yaml
+2: cat
+```
+
+then
+
+```bash
+yq eval '.[2]' sample.yml
+```
+
+will output
+
+```yaml
+cat
+```
+
+## Maps with non existing numeric keys
+
+Given a sample.yml file of:
+
+```yaml
+a: b
+```
+
+then
+
+```bash
+yq eval '.[0]' sample.yml
+```
+
+will output
+
+```yaml
+null
+```
+
+## Traversing merge anchors
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval '.foobar.a' sample.yml
+```
+
+will output
+
+```yaml
+foo_a
+```
+
+## Traversing merge anchors with override
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval '.foobar.c' sample.yml
+```
+
+will output
+
+```yaml
+foo_c
+```
+
+## Traversing merge anchors with local override
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval '.foobar.thing' sample.yml
+```
+
+will output
+
+```yaml
+foobar_thing
+```
+
+## Splatting merge anchors
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval '.foobar[]' sample.yml
+```
+
+will output
+
+```yaml
+foo_c
+foo_a
+foobar_thing
+```
+
+## Traversing merge anchor lists
+
+Note that the later merge anchors override previous
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval '.foobarList.thing' sample.yml
+```
+
+will output
+
+```yaml
+bar_thing
+```
+
+## Splatting merge anchor lists
+
+Given a sample.yml file of:
+
+```yaml
+foo: &foo
+  a: foo_a
+  thing: foo_thing
+  c: foo_c
+bar: &bar
+  b: bar_b
+  thing: bar_thing
+  c: bar_c
+foobarList:
+  b: foobarList_b
+  !!merge <<:
+    - *foo
+    - *bar
+  c: foobarList_c
+foobar:
+  c: foobar_c
+  !!merge <<: *foo
+  thing: foobar_thing
+```
+
+then
+
+```bash
+yq eval '.foobarList[]' sample.yml
+```
+
+will output
+
+```yaml
+bar_b
+foo_a
+bar_thing
+foobarList_c
+```
+
+## Select multiple indices
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  - a
+  - b
+  - c
+```
+
+then
+
+```bash
+yq eval '.a[0, 2]' sample.yml
+```
+
+will output
+
+```yaml
+a
+c
+```

operators/union.md

@@ -0,0 +1,42 @@
+# Union
+
+This operator is used to combine different results together.
+
+## Combine scalars
+
+Running
+
+```bash
+yq eval --null-input '1, true, "cat"'
+```
+
+will output
+
+```yaml
+1
+true
+cat
+```
+
+## Combine selected paths
+
+Given a sample.yml file of:
+
+```yaml
+a: fieldA
+b: fieldB
+c: fieldC
+```
+
+then
+
+```bash
+yq eval '.a, .c' sample.yml
+```
+
+will output
+
+```yaml
+fieldA
+fieldC
+```

operators/unique.md

@@ -0,0 +1,107 @@
+# Unique
+
+This is used to filter out duplicated items in an array.
+
+## Unique array of scalars (string/numbers)
+
+Given a sample.yml file of:
+
+```yaml
+- 1
+- 2
+- 3
+- 2
+```
+
+then
+
+```bash
+yq eval 'unique' sample.yml
+```
+
+will output
+
+```yaml
+- 1
+- 2
+- 3
+```
+
+## Unique nulls
+
+Unique works on the node value, so it considers different representations of nulls to be different
+
+Given a sample.yml file of:
+
+```yaml
+- ~
+- null
+- ~
+- null
+```
+
+then
+
+```bash
+yq eval 'unique' sample.yml
+```
+
+will output
+
+```yaml
+- ~
+- null
+```
+
+## Unique all nulls
+
+Run against the node tag to unique all the nulls
+
+Given a sample.yml file of:
+
+```yaml
+- ~
+- null
+- ~
+- null
+```
+
+then
+
+```bash
+yq eval 'unique_by(tag)' sample.yml
+```
+
+will output
+
+```yaml
+- ~
+```
+
+## Unique array object fields
+
+Given a sample.yml file of:
+
+```yaml
+- name: harry
+  pet: cat
+- name: billy
+  pet: dog
+- name: harry
+  pet: dog
+```
+
+then
+
+```bash
+yq eval 'unique_by(.name)' sample.yml
+```
+
+will output
+
+```yaml
+- name: harry
+  pet: cat
+- name: billy
+  pet: dog
+```

operators/variable-operators.md

@@ -0,0 +1,127 @@
+# Variable Operators
+
+Like the `jq` equivalents, variables are sometimes required for the more complex expressions (or swapping values between fields).
+
+Note that there is also an additional `ref` operator that holds a reference (instead of a copy) of the path, allowing you to make multiple changes to the same path.
+
+## Single value variable
+
+Given a sample.yml file of:
+
+```yaml
+a: cat
+```
+
+then
+
+```bash
+yq eval '.a as $foo | $foo' sample.yml
+```
+
+will output
+
+```yaml
+cat
+```
+
+## Multi value variable
+
+Given a sample.yml file of:
+
+```yaml
+- cat
+- dog
+```
+
+then
+
+```bash
+yq eval '.[] as $foo | $foo' sample.yml
+```
+
+will output
+
+```yaml
+cat
+dog
+```
+
+## Using variables as a lookup
+
+Example taken from [jq](https://stedolan.github.io/jq/manual/#Variable/SymbolicBindingOperator:...as$identifier|...)
+
+Given a sample.yml file of:
+
+```yaml
+"posts":
+  - "title": Frist psot
+    "author": anon
+  - "title": A well-written article
+    "author": person1
+"realnames":
+  "anon": Anonymous Coward
+  "person1": Person McPherson
+```
+
+then
+
+```bash
+yq eval '.realnames as $names | .posts[] | {"title":.title, "author": $names[.author]}' sample.yml
+```
+
+will output
+
+```yaml
+title: Frist psot
+author: Anonymous Coward
+title: A well-written article
+author: Person McPherson
+```
+
+## Using variables to swap values
+
+Given a sample.yml file of:
+
+```yaml
+a: a_value
+b: b_value
+```
+
+then
+
+```bash
+yq eval '.a as $x  | .b as $y | .b = $x | .a = $y' sample.yml
+```
+
+will output
+
+```yaml
+a: b_value
+b: a_value
+```
+
+## Use ref to reference a path repeatedly
+
+Note: You may find the `with` operator more useful.
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  b: thing
+  c: something
+```
+
+then
+
+```bash
+yq eval '.a.b ref $x | $x = "new" | $x style="double"' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  b: "new"
+  c: something
+```

operators/with.md

@@ -0,0 +1,81 @@
+# With
+
+Use the `with` operator to conveniently make multiple updates to a deeply nested path, or to update array elements relatively to each other. The first argument expression sets the root context, and the second expression runs against that root context.
+
+## Update and style
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  deeply:
+    nested: value
+```
+
+then
+
+```bash
+yq eval 'with(.a.deeply.nested ; . = "newValue" | . style="single")' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  deeply:
+    nested: 'newValue'
+```
+
+## Update multiple deeply nested properties
+
+Given a sample.yml file of:
+
+```yaml
+a:
+  deeply:
+    nested: value
+    other: thing
+```
+
+then
+
+```bash
+yq eval 'with(.a.deeply ; .nested = "newValue" | .other= "newThing")' sample.yml
+```
+
+will output
+
+```yaml
+a:
+  deeply:
+    nested: newValue
+    other: newThing
+```
+
+## Update array elements relatively
+
+The second expression runs with each element of the array as it's contextual root. This allows you to make updates relative to the element.
+
+Given a sample.yml file of:
+
+```yaml
+myArray:
+  - a: apple
+  - a: banana
+```
+
+then
+
+```bash
+yq eval 'with(.myArray[] ; .b = .a + " yum")' sample.yml
+```
+
+will output
+
+```yaml
+myArray:
+  - a: apple
+    b: apple yum
+  - a: banana
+    b: banana yum
+```

upgrading-from-v3.md

@@ -0,0 +1,236 @@
+# Upgrading from V3
+
+Version 4 of `yq` is quite different from previous versions (and I apologise for that) - however it will be very familiar if you have used `jq` before as it now uses a similar syntax. Most commands that you could do in `v3` are longer in `v4` as a result of having a more expressive syntax language.
+
+Note that `v4` by default now:
+
+* prints all documents of a yaml file.
+* prints in color (when outputting to a terminal).
+* document separators are printed out by default
+
+## How to do v3 things in v4:
+
+In `v3` yq had seperate commands for reading/writing/deleting and more. In `v4` all these have been embedded into a single expression you specify to either the `eval` command (which runs the expression against each yaml document for each file given in sequence) or the `eval-all` command, which reads all documents of all files, and runs the given expression once.
+
+Many flags from `v3` have been put into the expression language, for instance `stripComments` allowing you to specify which nodes to strip comments from instead of only being able to apply the flag to the entire document.
+
+Lets have a look at the commands for the most common tasks:
+
+### Navigating
+
+v3:
+
+```
+yq r sample.yaml 'a.b.c'
+```
+
+v4:
+
+```
+yq e '.a.b.c' sample.yaml
+```
+
+### Reading with default value
+
+v3:
+
+```
+yq r sample.yaml --defaultValue frog path.not.there
+```
+
+v4: (use the [alternative](broken-reference) operator)
+
+```
+yq e '.path.not.there // "frog"' sample.yaml
+```
+
+
+
+### Finding nodes
+
+v3:
+
+```bash
+yq r sample.yaml 'a.(b.d==cat).f'
+```
+
+v4:
+
+```bash
+yq eval '.a | select(.b.d == "cat") | .f' sample.yaml
+```
+
+### Recursively match nodes
+
+v3:
+
+```
+yq r sample.yaml 'thing.**.name'
+```
+
+v4:
+
+```
+yq e '.thing | .. | select(has("name"))' sample.yaml
+```
+
+### Multiple documents
+
+v3:
+
+```bash
+yq r -d1 sample.yaml 'b.c'
+```
+
+v4 (via the document index operator):
+
+```bash
+yq eval 'select(documentIndex == 1) | .b.c' sample.yml
+```
+
+### Updating / writing documents
+
+v3:
+
+```
+yq w sample.yaml 'a.b.c' fred
+```
+
+v4:
+
+```
+yq eval '.a.b.c = "fred"' sample.yaml
+```
+
+### Deleting documents
+
+v3:
+
+```bash
+yq d sample.yaml 'a.b.c'
+```
+
+v4:
+
+```bash
+yq eval 'del(.a.b.c)' sample.yaml
+```
+
+### Merging documents
+
+Like `jq`, merge is done via the multiply operator. You will need to use the eval-all command to load all documents into memory at once, and then use the file operator to select the file nodes to merge.
+
+```bash
+yq eval-all 'select(fileIndex == 0) * select(filename == "file2.yaml")' file1.yaml file2.yaml
+```
+
+### Prefix yaml
+
+Use the [Create / Collect Into Object ](broken-reference)operator to create a new object with the desired prefix. 
+
+v3:
+
+```
+yq p data1.yaml c.d
+```
+
+v4:
+
+```
+yq eval '{"c": {"d": . }}' data1.yml
+```
+
+### Create new yaml documents
+
+Note that in v4 you can no longer run expressions against an empty file to populate it - because the file is empty, there are no matches for `yq` to run through the expression pipeline - for what it's worth, this is what `jq` does as well. Instead use the `--null-input/-n` flag and pipe out the results to the file you want directly (see example below).
+
+v3:
+
+```
+yq n b.c cat
+```
+
+v4:
+
+```
+yq e -n '.b.c = "cat"'
+```
+
+### Validate documents
+
+v3:
+
+```
+yq validate some.file
+```
+
+v4:
+
+```
+yq e 'true' some.file > /dev/null
+```
+
+Note that passing 'true' as the expression saves having to reencode the yaml (only to pipe it to stdout). In v4 you can also do a slightly more sophisticated validation and assert the tag on the root level, so you can ensure the yaml file is a map or array at the top level:
+
+```
+yq e --exit-status 'tag == "!!map" or tag== "!!seq"' some.file > /dev/null
+```
+
+### Comparing yaml files
+
+v3:
+
+```
+yq compare --prettyPrint file1.yml file2.yml 
+```
+
+v4:
+
+In v4 there is no built in compare command, instead it relies on using diff. The downside is longer syntax, the upside is that you can use the full power of diff.
+
+```
+diff <(yq e -P file1.yml) <(yq e -P file2.yml)
+```
+
+### Script files
+
+v3 had a script feature that let you run an array of commands specified in a file in one go. The format for this looked like
+
+```yaml
+- command: update 
+  path: a.key1
+  value: things
+- command: delete
+  path: a.ab.key2
+```
+
+V4 doesn't have a similar feature, however the fact that you can run multiple operations in a single expression makes it easier to come up with a shell script that does the same thing:
+
+```bash
+#!/bin/bash
+
+yq e '
+  .a.key1 = "things" |
+  del(.a.ab.key2)
+' ./examples/data1.yaml
+```
+
+### Some new things you can do in v4:
+
+Construct dynamic yaml [maps ](broken-reference)and [arrays ](broken-reference)based on input yaml
+
+Using the [union ](broken-reference)operator, you can run multiple updates in one go and read multiple paths in one go
+
+Fine grain merging of maps using the [multiply](broken-reference) operator
+
+Read and and control yaml metadata better (e.g. [tags](broken-reference), [paths](broken-reference), [document indexes](broken-reference), [anchors and aliases](broken-reference), [comments](broken-reference)).
+
+Work with multiple files (not just for merge)
+
+The underlying expression language is much more powerful than `v3` so expect to see more features soon!
+
+
+
+
+
+###

usage/convert.md

@@ -0,0 +1,97 @@
+# Working with JSON
+
+## Yaml to Json
+
+To convert output to json, use the `--output-format=json` (or `-o=j`) flag. You can change the json output format by using the [indent](output-format.md#indent) flag. 
+
+Given a sample.yaml file of:
+
+```yaml
+b:
+  c: 2
+```
+
+then
+
+```bash
+yq eval -o=j sample.yaml
+```
+
+will output
+
+```javascript
+{
+  "b": {
+    "c": 2
+  }
+}
+```
+
+To format the json:
+
+```yaml
+yq eval -o=j -I=0 sample.yaml
+```
+
+will yield
+
+```yaml
+{"b":{"c":2}}
+```
+
+### Multiple matches
+
+Each matching yaml node will be converted to json and printed out as a separate json doc. You may want to set the [indent](output-format.md#indent) flags to 0 if you want a json doc per line.
+
+Given a sample.yaml file of:
+
+```yaml
+bob:
+  c: 2
+bab:
+  c: 5
+```
+
+then
+
+```bash
+yq eval -o=j '.b*' sample.yaml
+```
+
+will output
+
+```javascript
+{
+  "c": 2
+}
+{
+  "c": 5
+}
+```
+
+## Json to Yaml
+
+To read in json, just pass in a json file instead of yaml, it will just work - as json is a subset of yaml. However, you will probably want to use the [Style Operator](broken-reference) or `--prettyPrint/-P` flag to make look more like an idiomatic yaml document. This can be done by resetting the style of all elements.
+
+e.g given a json file
+
+```javascript
+{"a":"Easy! as one two three","b":{"c":2,"d":[3,4]}}
+```
+
+then
+
+```bash
+yq eval -P sample.json
+```
+
+will output
+
+```yaml
+a: Easy! as one two three
+b:
+  c: 2
+  d:
+  - 3
+  - 4
+```

usage/front-matter.md

@@ -0,0 +1,50 @@
+# Front Matter
+
+`yq` can process files with `yaml` front matter (e.g. jekyll, assemble and others) - this is done via the `--front-matter/-f` flag.
+
+## Process front matter
+
+Use `--front-matter=process` to process the front matter, that is run the expression against the `yaml` content, and output back the entire file, included the non-yaml content block. For example:
+
+File:
+
+```
+---
+a: apple
+b: bannana
+---
+<h1>I like {{a}} and {{b}} </h1>
+```
+
+The running
+
+```
+yq e --front-matter=process '.a="chocolate"' file.jekyll
+```
+
+Will yield:
+
+```
+---
+a: chocolate
+b: bannana
+---
+<h1>I like {{a}} and {{b}} </h1>
+```
+
+## Extract front matter
+
+Running with `--front-matter=extract` will only output the yaml contents and ignore the rest. From the previous example, if you were to instead run:
+
+```
+yq e --front-matter=extract '.a="chocolate"' file.jekyll
+```
+
+Then this would yield:
+
+```
+---
+a: chocolate
+b: bannana
+```
+

usage/github-action.md

@@ -0,0 +1,29 @@
+# GitHub Action
+
+You can use `yq` in your GitHub action, for instance:
+
+```yaml
+  - uses: actions/checkout@v2
+  - name: Get SDK Version from config
+    id: lookupSdkVersion
+    uses: mikefarah/yq@master
+    with:
+      cmd: yq eval '.renutil.version' 'config.yml'
+  - name: Restore Cache
+    id: restore-cache
+    uses: actions/cache@v2
+    with:
+      path: ../renpy
+      key:  ${{ runner.os }}-sdk-${{ steps.lookupSdkVersion.outputs.result }}
+      restore-keys: |
+        ${{ runner.os }}-sdk
+  # ... more
+```
+
+The `yq` action sets a `result` variable in its output, making it available to subsequent steps. In this case it's available as `steps.lookupSdkVersion.outputs.result`.
+
+Details of how the GitHub action itself is configured can be found [here](https://github.com/mikefarah/yq/issues/844#issuecomment-856700574)
+
+If you [enable step debug logging](https://docs.github.com/en/actions/managing-workflow-runs/enabling-debug-logging#enabling-step-debug-logging), you can see additional information about the exact command sent as well as the response returned within the GitHub Action logs.
+
+Thanks @[**devorbitus**](https://github.com/devorbitus)**!**

usage/output-format.md

@@ -0,0 +1,102 @@
+---
+description: Flags to control yaml and json output format
+---
+
+# Output format
+
+These flags are available for all `yq` commands. 
+
+## Color
+
+By default, `yq` prints with colours if it detects a terminal. You can manully this by using either
+
+The `--colors/-C`flag to force print with colors. 
+
+The \``--no-colors/-M` flag to force print without colours
+
+## Pretty Print
+
+To print out idiomatic `yaml` use the `--prettyPrint/-P` flag. Note that this is shorthand for using the [style](broken-reference) operator `... style=""`
+
+## Indent
+
+Use the indent flag `--indent/-I` to control the number of spaces used for indentation. This also works for JSON output. The default value is 2. 
+
+Note that lists are indented at the same level as the map key at indent level 2, but are more deeply indented at indent level 4 and greater. This is (currently) a quirk of the underlying [yaml parser](https://github.com/go-yaml/yaml/tree/v3).
+
+Given:
+
+```
+apples:
+  collection:
+  - name: Green
+  - name: Blue
+  favourite: Pink Lady
+```
+
+Then:
+
+```
+yq e -I4 sample.yaml
+```
+
+Will print out:
+
+```yaml
+apples:
+    collection:
+      - name: Green
+      - name: Blue
+    favourite: Pink Lady
+```
+
+This also works with json
+
+```
+yq e -j -I4 sample.yaml
+```
+
+yields
+
+```javascript
+{
+    "apples": {
+        "collection": [
+            {
+                "name": "Green"
+            },
+            {
+                "name": "Blue"
+            }
+        ],
+        "favourite": "Pink Lady"
+    }
+}
+```
+
+## Unwrap scalars
+
+By default scalar values are 'unwrapped', that is only their value is printed (except when outputting as JSON). To print out the node as-is, with the original formatting an any comments pass in `--unwrapScalar=false`
+
+Given data.yml:
+
+```yaml
+a: "Things" # cool stuff
+```
+
+Then:
+
+`yq e --unwrapScalar=false '.a' data.yml`
+
+Will yield:
+
+```yaml
+"Things" # cool stuff
+```
+
+where as without setting the flag to false you would get:
+
+```yaml
+Things
+```
+

usage/properties.md

@@ -0,0 +1,34 @@
+# Working with Properties
+
+## Yaml to Properties
+
+To convert to property file format, use `--outputformat=props` or `-o=p`. Porting the comments from the `yaml` file to the property file is still in progress, currently line comments on the node values will be copied across. 
+
+Given a sample file of:
+
+```yaml
+# block comments don't come through
+person: # neither do comments on maps
+    name: Mike # comments on values appear
+    pets: 
+    - cat # comments on array values appear
+    food: [pizza] # comments on arrays do not
+```
+
+then
+
+```bash
+yq eval -o=p sample.yaml
+```
+
+will output:
+
+```
+# comments on values appear
+person.name = Mike
+
+# comments on array values appear
+person.pets.0 = cat
+person.food.0 = pizza
+```
+

usage/tips-and-tricks.md

@@ -0,0 +1,134 @@
+# Tips, Tricks, Troubleshooting
+
+## Validating yaml files
+
+Yaml files can be surprisingly lenient in what can be parsed as a yaml file. A reasonable way of validation a yaml file is to ensure the top level is a map or array (although it is valid yaml to have scalars at the top level, but often this is not what you want). This can be done by:
+
+```
+yq e --exit-status 'tag == "!!map" or tag== "!!seq"' file.txt > /dev/null
+```
+
+## Split expressions over multiple lines to improve readablity
+
+Feel free to use multiple lines in your expression to improve readability.
+
+```bash
+yq eval --inplace '
+  .a.b.c[0].frog = "thingo" |
+  .a.b.c[0].frog style= "double" |
+  .different.path.somehere = "foo" |
+  .different.path.somehere style= "folded"
+' my_file.yaml
+```
+
+## Create bash array
+
+Given a yaml file like
+
+```yaml
+coolActions:
+  - create
+  - edit
+  - delete
+```
+
+You can create a bash array named `actions` by:
+
+```bash
+> readarray actions < <(yq e '.coolActions[]' sample.yaml)
+> echo "${actions[1]}"
+edit
+```
+
+## Set contents from another file
+
+Use an environment variable with the `strenv` operator to inject the contents from an environment variable.&#x20;
+
+```bash
+LICENSE=$(cat LICENSE) yq eval -n '.a = strenv(LICENSE)'
+```
+
+## Special characters in strings
+
+The `strenv` operator is a great way to handle special characters in strings:
+
+```bash
+VAL='.a |!@  == "string2"' yq e '.a = strenv(VAL)' example.yaml
+```
+
+## Quotes in Windows Powershell
+
+Powershell has its [own](https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about\_quoting\_rules?view=powershell-7.1) way of handling quotes:
+
+```bash
+PS > yq e -n '.test = ""something""'
+test: something
+PS >
+```
+
+## Merge / combine all documents into one
+
+To merge all given yaml files into one, use the `reduce` operator with the `*` (multiply) operator. Note the use of `ea` or `eval-all` to load all files into memory so that they can be merged.
+
+```
+yq ea '. as $item ireduce ({}; . * $item )' file1.yml file2.yml ...
+```
+
+## Creating a new file / working with blank documents
+
+To create a new `yaml` file simply:
+
+```
+yq e -n '.someNew="content"' > newfile.yml
+```
+
+## Comparing yaml files
+
+The best way to run a diff is to use `yq` to normalise the yaml files and then just use diff. Here is a simple example of using pretty print `-P` to normalise the styling and running diff:
+
+```
+diff <(yq e -P examples/data1.yaml) <(yq e -P examples/data2.yaml)
+```
+
+This way you can use the full power of `diff` and normalise the yaml files as you like - for instance you may also want to remove all comments using `... comments=""`
+
+## Reading multiple streams (STDINs)
+
+Like `diff` and other bash commands, you can use `<(exp)` to pipe in multiple streams of data into `yq`. instance:
+
+```
+yq e '.apple' <(curl -s https://somewhere/data1.yaml) <(cat file.yml)
+```
+
+## Updating deeply selected paths
+
+The most important thing to remember to do is to have brackets around the LHS expression - otherwise what `yq` will do is first filter by the selection, and then, separately, update the filtered result and return that subset.
+
+```
+yq '(.foo.bar[] | select(name == "fred) | .apple) = "cool"'
+```
+
+## Combining multiple files into one
+
+In order to combine multiple yaml files into a single file (with `---` separators) you can just:
+
+```
+yq e '.' somewhere/*.yaml
+```
+
+## &#x20;Multiple updates to the same path
+
+You can use the [with](../operators/with.md) operator to set a nested context:
+
+```
+yq eval 'with(.a.deeply ; .nested = "newValue" | .other= "newThing")' sample.yml
+```
+
+The first argument expression sets the root context, and the second expression runs against that root context.
+
+## yq adds a !!merge tag automatically
+
+The merge functionality from yaml v1.1 (e.g. `<<:`has actually been removed in the 1.2 spec. Thankfully, `yq` underlying yaml parser still supports that tag - and it's extra nice in that it explicitly puts the `!!merge` tag on key of the map entry. This tag tells other yaml parsers that this entry is a merge entry, as opposed to a regular string key that happens to have a value of `<<:`. This is backwards compatible with the 1.1 spec of yaml, it's simply an explicit way of specifying the type (for instance, you can use a `!!str` tag to enforce a particular value to be a string.
+
+Although this does affect the readability of the yaml to humans, it still works and processes fine with various yaml processors.
+