### Serve Documentation Website

Source: https://github.com/jqlang/jq/wiki/Docs-and-tests

Starts a local web server to display the documentation website. Requires a working Ruby setup.

```bash
rake serve
```

--------------------------------

### Initialize and Install jq with Flox

Source: https://github.com/jqlang/jq/wiki/Installation

Demonstrates initializing a new environment with Flox and then installing jq into it. This is for managing development environments.

```console
$ flox init
✨ Created environment 'tmp.kAmqr3RpBT' (aarch64-darwin)

Next:
  $ flox search <package>    <- Search for a package
  $ flox install <package>   <- Install a package into an environment
  $ flox activate            <- Enter the environment
  $ flox edit                <- Add environment variables and shell hooks

$ flox install jq
✅ 'jq' installed to environment 'tmp.bCViSurqsu'
$ flox activate
✅ You are now using the environment 'tmp.bCViSurqsu'.
To stop using this environment, type 'exit'

flox [tmp.bCViSurqsu] $ jq --version
jq-1.7.1
```

--------------------------------

### Install 0install script

Source: https://github.com/jqlang/jq/wiki/Installation

Downloads and makes executable the 0install installation script. Follow the script's directions for completion.

```bash
curl -O https://get.0install.net/0install.sh && chmod +x 0install.sh
./0install.sh
```

--------------------------------

### Install jq with Homebrew

Source: https://github.com/jqlang/jq/wiki/Installation

Installs the stable version of jq using the Homebrew package manager. Verify Homebrew is installed first.

```bash
$ brew install jq
```

--------------------------------

### Add jq using 0install

Source: https://github.com/jqlang/jq/wiki/Installation

Installs the most recent version of jq known to 0install. Ensure 0install is installed and ~/bin/jq does not exist.

```bash
0install add jq https://apps.0install.net/utils/jq.xml
```

--------------------------------

### Install jq using Chocolatey on Windows

Source: https://github.com/jqlang/jq/wiki/Installation

Installs a pre-compiled jq binary on Windows using the Chocolatey package manager.

```bash
choco install jq
```

--------------------------------

### Install Bison 3 from Source

Source: https://github.com/jqlang/jq/wiki/Installation

Installs Bison 3 from source, a dependency for building jq. Ensure you have wget and tar installed.

```bash
cd /tmp
wget http://ftp.gnu.org/gnu/bison/bison-3.0.3.tar.gz
tar -xvzf bison-3.0.3.tar.gz
cd bison-3.0.3
sudo port install m4
./configure --prefix=/usr/local/bison
sudo make install
sudo ln -s /usr/local/bison/bin/bison /usr/bin/bison
```

--------------------------------

### Example Manual Entry Structure

Source: https://github.com/jqlang/jq/wiki/Docs-and-tests

Illustrates the structure of an example within the manual's YAML file. 'program', 'input', and 'output' are YAML strings and lists of strings respectively.

```yaml
examples:
  - program: '.foo, .bar'
    input: '{"foo": 42, "bar": "something else", "baz": true}'
    output: ['42', '"something else"']
```

--------------------------------

### Install ruby-jq for Ruby

Source: https://github.com/jqlang/jq/wiki/FAQ

Install the ruby-jq gem for Ruby development. Refer to the GitHub repository for more details.

```bash
gem install ruby-jq # For details, see https://github.com/winebarrel/ruby-jq
```

--------------------------------

### Install jq using Homebrew on Linux/macOS

Source: https://github.com/jqlang/jq/wiki/Installation

Installs jq using Homebrew. This command is run within a bash window after installing bash for Windows 10 and Homebrew for Linux.

```bash
brew install jq
```

--------------------------------

### Add a specific jq version using 0install

Source: https://github.com/jqlang/jq/wiki/Installation

Installs a particular version of jq, e.g., 1.4, using 0install. Specify the version and a name for the installation.

```bash
0install add --version=1.4 jq1.4 https://apps.0install.net/utils/jq.xml
```

--------------------------------

### Sync Dependencies with pipenv

Source: https://github.com/jqlang/jq/blob/master/docs/README.md

After installing pipenv, navigate to the `docs/` directory and run this command to install project dependencies. This ensures you have all necessary tools for documentation generation.

```bash
pipenv sync
```

--------------------------------

### Build Documentation Website

Source: https://github.com/jqlang/jq/wiki/Docs-and-tests

Generates the complete documentation website in the 'output' folder. Requires a working Ruby setup.

```bash
rake build
```

--------------------------------

### Install jq for Python

Source: https://github.com/jqlang/jq/wiki/FAQ

Install the jq library for Python using pip. Multiple jq Python wrappers are available.

```bash
pip install jq # For details, see https://pypi.python.org/pypi/jq
```

```bash
pip install pyjq # For details, see https://pypi.python.org/pypi/pyjq
```

```bash
pip install jqpy # For details, see https://baterflyrity.github.io/jqpy/
```

--------------------------------

### Install jq with MacPorts

Source: https://github.com/jqlang/jq/wiki/Installation

Installs jq version 1.5 using the MacPorts package manager. Ensure MacPorts is installed before running this command.

```bash
sudo port install jq
```

--------------------------------

### Build jq from Source

Source: https://github.com/jqlang/jq/blob/master/README.md

Instructions for building jq from source, including submodule updates, configuration, and compilation. Ensure all dependencies are installed.

```console
git submodule update --init    # if building from git to get oniguruma
autoreconf -i                  # if building from git
./configure --with-oniguruma=builtin
make clean                     # if upgrading from a version previously built from source
make -j8
make check
sudo make install
```

--------------------------------

### jq foreach loop with state variable example

Source: https://github.com/jqlang/jq/blob/master/NEWS.md

Demonstrates the `foreach` construct in jq. The first example shows a basic usage, and the second illustrates how the state variable is correctly maintained across iterations, fixing a previous issue where it was reset.

```sh
$ jq -n '[1, 2] | foreach .[] as $x (0, 1; . + $x)'

```

```sh
$ jq -n 'reduce range(5) as $x (0; .+$x | select($x!=2))'

```

```sh
$ jq -nc '[foreach range(5) as $x (0; .+$x | select($x!=2); [$x,.])]'

```

--------------------------------

### Install latest jq from Homebrew HEAD

Source: https://github.com/jqlang/jq/wiki/Installation

Installs the most recent development version of jq from the Homebrew HEAD. Use with caution as it may be unstable.

```bash
brew install --HEAD jq
```

--------------------------------

### Install RVM and Ruby for Docs

Source: https://github.com/jqlang/jq/wiki/Installation

Installs RVM and a specific Ruby version, which was previously a dependency for building jq documentation. Note that python is now used for building docs.

```bash
cd ~/jq/docs
curl -L https://get.rvm.io | bash -s stable --ruby=1.9.3
cd docs
bundle install
```

--------------------------------

### Install Oniguruma Dependency

Source: https://github.com/jqlang/jq/wiki/Installation

Installs the Oniguruma regex library from source, a dependency for jq. This is a manual compilation process.

```bash
wget https://web.archive.org/web/20150803013327/http://www.geocities.jp/kosako3/oniguruma/archive/onig-5.9.6.tar.gz
tar -xf onig-5.9.6.tar.gz
cd onig-5.9.6
./configure
make
sudo make install
```

--------------------------------

### Rename keys using translate_keys (Example 1)

Source: https://github.com/jqlang/jq/wiki/FAQ

Example demonstrating how to prepend a string to all keys in a JSON entity using the `translate_keys` function.

```jq
{"a": 1, "b": [{"c":2}] } | translate_keys( "@" + . )
```

--------------------------------

### Install jq Release Binary with Dockerfile

Source: https://github.com/jqlang/jq/wiki/Installation

Installs a specific version of the jq release binary within a Docker container. It downloads the binary, verifies its signature, and makes it executable.

```dockerfile
ENV JQ_VERSION='1.5'

RUN wget --no-check-certificate https://raw.githubusercontent.com/jqlang/jq/master/sig/jq-release.key -O /tmp/jq-release.key && \
    wget --no-check-certificate https://raw.githubusercontent.com/jqlang/jq/master/sig/v${JQ_VERSION}/jq-linux64.asc -O /tmp/jq-linux64.asc && \
    wget --no-check-certificate https://github.com/jqlang/jq/releases/download/jq-${JQ_VERSION}/jq-linux64 -O /tmp/jq-linux64 && \
    gpg --import /tmp/jq-release.key && \
    gpg --verify /tmp/jq-linux64.asc /tmp/jq-linux64 && \
    cp /tmp/jq-linux64 /usr/bin/jq && \
    chmod +x /usr/bin/jq && \
    rm -f /tmp/jq-release.key && \
    rm -f /tmp/jq-linux64.asc && \
    rm -f /tmp/jq-linux64
```

--------------------------------

### Run decNumber Example 1

Source: https://github.com/jqlang/jq/blob/master/vendor/decNumber/readme.txt

Execute the compiled example1 program with two numeric arguments to observe their addition.

```bash
example1 1.23 1.27
```

--------------------------------

### jq zip function and testzip usage

Source: https://github.com/jqlang/jq/wiki/X---Experimental-Benchmarks

Defines a 'zip' function to combine headers with data and a 'testzip' function to create a large dataset for testing. The example shows how to use 'testzip' to generate a dataset of a specified size and then get its length.

```jq
def zip(headers):
  . headers as $headers
  | [$headers, .] | transpose | map({(.[0]): .[1]}) | add ;

def testzip(n):
  [range(0;n)] as $row
  | $row | zip( $row|map(tostring) ) ;

testzip(1000000) | length
```

--------------------------------

### Install pipenv

Source: https://github.com/jqlang/jq/blob/master/docs/README.md

Use this command to install pipenv, a dependency manager for Python projects. You may need to use `pip3` depending on your system configuration.

```bash
pip install pipenv
```

--------------------------------

### decNumber Example 1 Output

Source: https://github.com/jqlang/jq/blob/master/vendor/decNumber/readme.txt

The expected output when running example1 with '1.23' and '1.27' as arguments, demonstrating decimal addition.

```text
1.23 + 1.27 => 2.50
```

--------------------------------

### Compile decNumber Example 1

Source: https://github.com/jqlang/jq/blob/master/vendor/decNumber/readme.txt

Compile example1.c along with decNumber.c and decContext.c. Compiler optimization is recommended. Ensure stdint.h is available or consult documentation for alternatives.

```bash
gcc -o example1 example1.c decNumber.c decContext.c
```

--------------------------------

### Install jsonic for non-strict JSON conversion

Source: https://github.com/jqlang/jq/wiki/FAQ

Install the jsonic package via npm to convert non-strict JSON formats to standard JSON.

```bash
npm install jsonic
```

--------------------------------

### jq binding syntax precedence change example

Source: https://github.com/jqlang/jq/blob/master/NEWS.md

Demonstrates a breaking change in jq's binding syntax precedence. The first example shows how `as $x` now binds correctly before unary operators, and the second shows binding before binary operators.

```sh
$ jq -nc '[-1 as $x | 1,$x]'

```

```sh
$ jq -nc '1 | . + 2 as $x | -$x'

```

--------------------------------

### Run All Tests

Source: https://github.com/jqlang/jq/wiki/Docs-and-tests

Executes all tests, including manual examples, jq-coded tests, and shell-coded tests. Recommended to run under Valgrind for memory leak detection.

```bash
make check
```

--------------------------------

### Generate Manual Page

Source: https://github.com/jqlang/jq/wiki/Docs-and-tests

Generates the roff manual page for jq. Requires a working Ruby setup.

```bash
make jq.1
```

--------------------------------

### Example: C-coded Built-in Calling jq Wrapper

Source: https://github.com/jqlang/jq/wiki/How-To:-Add-built-in-functions

When a C-coded builtin needs to interact with jq's execution context (e.g., call other jq functions), it should be wrapped by a jq-coded function. This example shows the concept, where `_sort_by_impl` is a C implementation called by a jq wrapper.

```jq
# jq wrapper for a C implementation
def sort_by(f):
  _sort_by_impl(f);

```

--------------------------------

### Cartesian Product Example

Source: https://github.com/jqlang/jq/wiki/How-to:-Avoid-Pitfalls

Demonstrates how jq generates Cartesian products when multiple values are piped or combined. Each element from the first set is combined with each element from the second.

```jq
3
4
3
4
```

```jq
$ jq -n '(1,2) as $i | (3,4) |  "\($i),\(.)"' 
"1,3"
"1,4"
"2,3"
"2,4"
```

--------------------------------

### Named Group Backreference Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Demonstrates backreferencing using named groups with relative level adjustments. This example shows how to reference groups based on their nesting depth.

```Ruby
r = Regexp.compile(<<'__REGEXP__'.strip, Regexp::EXTENDED)
(?<element> \g<stag> \g<content>* \g<etag> ){0}
(?<stag> < \g<name> \s* > ){0}
(?<name> [a-zA-Z_:]+ ){0}
(?<content> [^<&]+ (?:\g<element> | [^<&]+)* ){0}
(?<etag> </ \k<name+1> >){0}
\g<element>
__REGEXP__

p r.match('<foo>f<bar>bbb</bar>f</foo>').captures
```

--------------------------------

### Check jq executable path

Source: https://github.com/jqlang/jq/wiki/FAQ

If jq is installed but not running, try executing it using its full path. Ensure the binary file has execute permissions on Unix-like systems.

```bash
jq --version
```

--------------------------------

### Cross-compile Oniguruma for Windows 64-bit

Source: https://github.com/jqlang/jq/wiki/Cross-compilation

Builds the Oniguruma library for a 64-bit Windows target, installing it into a specified prefix.

```shell
: ; mkdir -p /home/build/proto/win64
: ; PATH=/home/build/mingw/mingw-w64-x86_64/bin:$PATH
: ; cd /home/build/ws/onig-5.9.5
: ; ./configure --target=win64-x86_64 --host=x86_64-w64-mingw32 --prefix=/home/build/proto/win64/usr/local
: ; make -j16 LDFLAGS=-all-static clean all install
```

--------------------------------

### Example Usage of Arithmetic Expression Evaluator

Source: https://github.com/jqlang/jq/wiki/Parsing-Expression-Grammars

Demonstrates how to use the 'evaluate' jq filter with a sample arithmetic expression string.

```bash
$ jq -f arithmetic.jq <<< "(1+2)*(3+4)+(1*1)"
   22

```

--------------------------------

### jq Closure Example

Source: https://github.com/jqlang/jq/wiki/Advanced-Topics

Illustrates how functions in jq are closures. This example shows a local variable '$a' captured by the argument closure 'x', demonstrating that the binding within 'foo' is not visible to 'x'.

```jq
def foo(x): .a as $a | x.b * 2;
{"a":{"a":3, "b":4}} | .a as $a | foo($a)
```

--------------------------------

### Cross-compile Oniguruma for Windows 32-bit

Source: https://github.com/jqlang/jq/wiki/Cross-compilation

Builds the Oniguruma library for a 32-bit Windows target, installing it into a specified prefix.

```shell
: ; mkdir -p /home/build/proto/win32
: ; PATH=/home/build/mingw/mingw-w32-x86_64/bin:$PATH
: ; cd /home/build/ws/onig-5.9.5
: ; ./configure --target=win32-i86 --host=i686-w64-mingw32 --prefix=/home/build/proto/win32/usr/local
: ; make -j16 LDFLAGS=-all-static clean all install
```

--------------------------------

### Display Manual Page

Source: https://github.com/jqlang/jq/wiki/Docs-and-tests

Displays the generated roff manual page in a pager, similar to 'man jq'. Requires a working Ruby setup.

```bash
nroff -man jq.1 | $PAGER
```

--------------------------------

### Build jq from source with alternative oniguruma

Source: https://github.com/jqlang/jq/wiki/Installation

Builds jq from source, allowing the use of an alternative oniguruma regex library. Requires autoconf and libtool. Ensure dependencies are installed.

```bash
autoreconf -i
./configure --disable-maintainer-mode
make
```

--------------------------------

### Compare jq and gojq regex behavior

Source: https://github.com/jqlang/jq/wiki/FAQ

This example highlights discrepancies in regex handling between jq 1.6 and gojq, specifically with `gsub` and the `test` function regarding end-of-string matching.

```bash
echo gsub:
for jq in jq-1.6 gojq
do
    echo $jq : $($jq -n '"aaa" | gsub("^a"; "b")' )
done

echo test:

for jq in jq-1.6 gojq
do
    echo $jq : $($jq -n '"abc\n" | test("c$")')
done
```

```text
gsub:
jq-1.6 : "bbb"
gojq : "baa"
test:
jq-1.6 : true
gojq : false
```

--------------------------------

### Cartesian Product Behavior Example in jq

Source: https://github.com/jqlang/jq/wiki/Advanced-Topics

Illustrates the Cartesian product behavior of some jq expressions. Note the difference in output between using `,` and `;` with `range`, and between `and` with comma-separated values versus piped values.

```jq
range(0,1;3,4)
```

```jq
range(0;3), range(0;4), range(1;3), range(1;4)
```

```jq
"\( (true, false) ) and \( (true, false) )"
```

```jq
(true, false) and (true, false)
```

--------------------------------

### Set up Bison for maintainer mode build

Source: https://github.com/jqlang/jq/wiki/Installation

Installs Bison version 3 using Homebrew and sets it as the primary version in the PATH. Required for building jq in maintainer mode.

```bash
$ brew install bison
# Ensure that this bison has priority than the system version.
$ export PATH="$(brew --prefix)/opt/bison/bin:$PATH"
```

--------------------------------

### Using path(..) to get all paths

Source: https://github.com/jqlang/jq/wiki/jq-Language-Description

Demonstrates how to use the `path/1` built-in with the `..` operator to extract all possible paths within a JSON object. This is useful for understanding the structure of the data.

```jq
$ printf '%s\n' '{"a":{"b":[{"c":0},{"d":1}]}}' | jq -c 'path(..)'
[]
["a"]
["a","b"]
["a","b",0]
["a","b",0,"c"]
["a","b",1]
["a","b",1,"d"]
```

--------------------------------

### Illustrative JSON Object

Source: https://github.com/jqlang/jq/wiki/For-JSONPath-users

The sample JSON object used throughout the examples to demonstrate JSONPath and jq queries.

```json
{
  "store": {
    "book": [
      {
        "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      {
        "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "price": 12.99
      },
      {
        "category": "fiction",
        "author": "Herman Melville",
        "isbn": "0-553-21311-3",
        "price": 8.99
      },
      {
        "category": "fiction",
        "author": "J. R. R. Tolkien",
        "isbn": "0-395-19395-8",
        "price": 22.99
      }
    ],
    "bicycle": {
      "color": "red",
      "price": 19.95
    }
  }
}
```

--------------------------------

### Build jq from source with built-in oniguruma

Source: https://github.com/jqlang/jq/wiki/Installation

Builds jq from source using the built-in oniguruma regex library. Requires autoconf, automake, and libtool. Ensure dependencies are installed.

```bash
cd modules/oniguruma
autoreconf -fi
cd ../..
autoreconf -i
./configure --with-oniguruma=builtin
make
```

--------------------------------

### Lookbehind with Alternatives Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Illustrates the use of lookbehind assertions with alternatives. Note that the subexpression within a lookbehind must be of fixed character length.

```Regex
(?<=a|bc)
```

```Regex
(?<=aaa(?:b|cd))
```

--------------------------------

### Convert JSON5 to JSON with json5

Source: https://github.com/jqlang/jq/wiki/FAQ

Install and use the json5 command-line tool to convert JSON5 files to standard JSON. The output file is named based on the input filename.

```bash
npm install json5
ln -s ~/node_modules/.bin/json5 ~/bin
json5 -c FILENAME.json5  # generates FILENAME.json
```

--------------------------------

### Example: Summing numbers with reduce in jq

Source: https://github.com/jqlang/jq/wiki/jq-Language-Description

Demonstrates using the 'reduce' primitive to sum numbers from a range. The update expression '. + $n' is applied to the accumulated state, with '$n' representing each successive input from 'range(5)'.

```jq
reduce range(5) as $n (0; .+$n)
```

--------------------------------

### Build jq Website

Source: https://github.com/jqlang/jq/blob/master/docs/README.md

Navigate to the `docs/` directory and execute this command to build the jq project website. This script compiles the website assets.

```bash
pipenv run python3 build_website.py
```

--------------------------------

### Backreference by Group Number Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

A basic example of backreferencing a captured group using its number.

```Regex
\1
```

--------------------------------

### Serve jq Website Locally

Source: https://github.com/jqlang/jq/blob/master/docs/README.md

After building the website, use this command to serve the generated output locally. This allows you to preview the website before deployment.

```bash
python3 -m http.server -d output
```

--------------------------------

### jq Mathematical Function Examples

Source: https://github.com/jqlang/jq/wiki/FAQ

Demonstrates the usage of various mathematical functions in jq, including trigonometric, logarithmic, and special functions like nan and infinite. Note that some functions are 0-arity filters.

```jq
atan2(1;1), hypot(3;4), pow(2;3), remainder(5; -2)
```

```jq
nan | isnan
```

```jq
infinite | isinfinite
```

--------------------------------

### Prepare build environment

Source: https://github.com/jqlang/jq/wiki/Cross-compilation

Commands to prepare the build environment, including autoreconf and configure.

```shell
: ; autoreconf -fi
: ; ./configure
: ; make distclean
```

--------------------------------

### jq Tail-Call Optimization (TCO) Example

Source: https://github.com/jqlang/jq/wiki/Advanced-Topics

Demonstrates tail-call optimization using a local recursive helper function '_range'. This pattern is necessary for TCO in jq versions 1.5rc1 and up, especially for functions without arguments.

```jq
def range(init; upto; by):
  def _range:
    if (by > 0 and . < upto) or (by < 0 and . > upto) then ., ((.+by)|_range)
    else .
    end;
  if by == 0 then init
  else init|_range
  end
  | select((by > 0 and . < upto) or (by < 0 and . > upto)) ;
```

--------------------------------

### Test Case Format

Source: https://github.com/jqlang/jq/wiki/Docs-and-tests

Defines the simple format for test cases in '.test' files: program on one line, input on the next, and output(s) on subsequent lines. Test cases are terminated by a blank line. Lines starting with '#' are comments.

```text
# This is a comment
.foo
{"foo": "bar"}
"bar"

.baz | . + 1
{"baz": 5}
6

```

--------------------------------

### JJ Path Syntax with Filters vs. JQ

Source: https://github.com/jqlang/jq/wiki/For-JJ-users

Demonstrates JJ path syntax with filtering conditions and their JQ equivalents, focusing on array element selection based on properties.

```shell
friends.#[last=="Murphy"].first    >> .friends[] | first(select(.last=="Murphy")) | .first
friends.#[last=="Murphy"]#.first   >> .friends[] | select(.last=="Murphy") | .first
friends.#[age>45]#.last            >> .friends[] | select(.age > 45) | .last
friends.#[first%"D*"].last         >> .friends[] | first(select(.first|startswith("D"))) | .last  # or test("^D")
```

--------------------------------

### Import JSON data using jq_each in SQLite

Source: https://github.com/jqlang/jq/wiki/FAQ

Demonstrates importing data from a JSON file into SQLite using the jq_each table-valued function. This example assumes the JSON file contains a single object.

```sql
insert into raw_data select * from jq_each(readfile('airline_routes.json'),
  '.[]|to_entries[] | {(.key): .value}');
```

--------------------------------

### Prepare Release Workspace

Source: https://github.com/jqlang/jq/wiki/Release-Production

Clone the repository, checkout the master branch, clean the workspace, and pull the latest changes and tags. Ensure autoreconf is run to correctly configure the build.

```bash
cd ~/workspaces # or whatever
git clone <your-dev-repo> jq-rel
cd jq-rel
git checkout -f master
git clean -fx
git pull -u
git pull --tags
autoreconf -fi
./configure ... && make dist
```

--------------------------------

### jq 'or' vs '//' operator examples

Source: https://github.com/jqlang/jq/wiki/FAQ

Illustrates the behavior of the 'or' and '//' operators in jq. '//' returns the first truthy value or the second expression's stream, while 'or' has different short-circuiting and stream concatenation semantics.

```jq
(null,1) or (2,3)
```

```jq
(null, 1, null,2) // (10, 20)
```

--------------------------------

### Build jq from source in maintainer mode

Source: https://github.com/jqlang/jq/wiki/Installation

Builds jq from source in maintainer mode. Requires oniguruma, autoconf, automake, and libtool installed via Homebrew. Ensure correct Bison version is prioritized.

```bash
$ mkdir github
$ cd github
$ git clone https://github.com/jqlang/jq.git
$ cd jq; autoreconf -i ; ./configure ; make
```

--------------------------------

### Lazy Evaluation with `limit/2` in jq

Source: https://github.com/jqlang/jq/wiki/jq-Language-Description

Demonstrates `limit/2` which outputs only the first N values from its second argument. The example shows that even a large range is efficiently processed due to this limiting behavior.

```jq
[limit(5; range(1000000))]
```

--------------------------------

### Import and Use Library Function in JQ

Source: https://github.com/jqlang/jq/wiki/Cookbook

Demonstrates how to import a JQ library file using the -L option and then use a function from that library. Ensure the library path is correctly specified.

```shell
jq -L $HOME/jq 'import "library" as lib;
   lib::walk(if type == "object" then del(.foo) else . end)' <<< '{"a":1, "foo": 2}'
```

--------------------------------

### NUL-Separated Output with --raw-output0

Source: https://github.com/jqlang/jq/blob/master/NEWS.md

Utilize the --raw-output0 option for NUL (zero byte) separated output, which is useful for piping to tools like xargs -0. Examples show its usage with xxd, xargs, and a while loop with read.

```sh
# will output a zero byte after each output
$ jq -n --raw-output0 '1,2,3' | xxd
00000000: 3100 3200 3300                           1.2.3.
```

```sh
# can be used with xargs -0
$ jq -n --raw-output0 '"a","b","c"' | xargs -0 -n1
a
b
c
```

```sh
$ jq -n --raw-output0 '"a b c", "d\ne\nf"' | xargs -0 printf '[%s]\n'
[a b c]
[d
e
f]
```

```sh
# can be used with read -d ''
$ while IFS= read -r -d '' json; do
>   jq '.name' <<< "$json"
> done < <(jq -n --raw-output0 '{name:"a b c"},{name:"d\ne\nf"}')
"a b c"
"d\ne\nf"
```

```sh
# also it's an error to output a string containing a NUL when using NUL separator
$ jq -n --raw-output0 '"\u0000"'
jq: error (at <unknown>): Cannot dump a string containing NUL with --raw-output0 option
```

--------------------------------

### Enable Documentation Builds

Source: https://github.com/jqlang/jq/blob/master/docs/README.md

Run this command in the jq root directory to enable documentation generation. This modifies the build configuration to include documentation targets.

```bash
./configure --enable-docs
```

--------------------------------

### Rename keys using translate_keys (Example 2)

Source: https://github.com/jqlang/jq/wiki/FAQ

Example demonstrating how to conditionally rename a specific key ('c' to 'C') in a JSON entity using the `translate_keys` function.

```jq
{"a": 1, "b": [{"c":2}] } | translate_keys( if . == "c" then "C" else . end )
```

--------------------------------

### Include and use a library function in jq

Source: https://github.com/jqlang/jq/wiki/Cookbook

Demonstrates how to include a jq library file and use its functions, such as 'walk/1', for data transformation.

```shell
jq 'include "library"; walk(if type == "object" then del(.foo) else . end)' <<< '{"a":1, "foo": 2}'
```

--------------------------------

### JJ Path Syntax Equivalents to JQ

Source: https://github.com/jqlang/jq/wiki/For-JJ-users

Illustrates basic JJ path syntax and its corresponding JQ expressions for accessing JSON elements.

```shell
@this              >>  .
@this.0            >>  .[0]
name.last          >>  .name.last
age                >>  .age
children           >>  .children
children.#         >>  .children|length
children.1         >>  .children[1]
child*.2           >>  to_entries[] | select(.key|test("^child")) | .value[2]
c?ildren.0         >>  to_entries[] | select(.key|test("^c.ildren$")) | .value[0]
fav\.movie         >>  .["fav.movie"]  # alternatively: ."fav.movie"
friends.#.first    >>  [.friends[].first] .  # or: .friends | map(.first)
friends.1.last     >>  .friends[1].last
```

--------------------------------

### jq number precision example

Source: https://github.com/jqlang/jq/wiki/FAQ

jq versions prior to 1.7 convert numbers to IEEE 754 64-bit values, potentially causing loss of precision. This example demonstrates how large numbers are handled.

```jq
jqMaster -M -n '123456789123456789123456789123456789123456789123456789.0000|[.,tostring]'
```

--------------------------------

### Subexpression Call by Group Number Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Demonstrates calling a subexpression using its group number.

```Regex
\g<n>
```

--------------------------------

### Build and Test jq

Source: https://github.com/jqlang/jq/wiki/Guide-for-Contributors

Build the jq project and run its tests using autoreconf, configure, and make. Ensure maintainer mode is enabled and Oniguruma is built internally.

```bash
$ autoreconf -fi
$ ./configure --enable-maintainer-mode --with-oniguruma=builtin
$ make -j4 check
```

--------------------------------

### Backreference by Group Name Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Demonstrates backreferencing a captured group using its assigned name.

```Regex
\k<name>
```

--------------------------------

### Subexpression Call by Group Name Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Shows calling a subexpression using its assigned group name.

```Regex
\g<name>
```

--------------------------------

### Accessing the First Two Books in Store

Source: https://github.com/jqlang/jq/wiki/For-JSONPath-users

Directly selects the first two books from the 'store.book' array.

```jq
.store.book[0:2]
```

--------------------------------

### Create and Activate Virtual Environment

Source: https://github.com/jqlang/jq/blob/master/docs/README.md

In some cases, you might need to manually create a virtual environment and activate it before syncing dependencies with pipenv. This isolates project dependencies.

```bash
virtualenv -p /usr/bin/python3 venv/
source venv/bin/activate
```

--------------------------------

### Build jq from Source

Source: https://github.com/jqlang/jq/wiki/Installation

Compiles jq from its source code using autoconf and make. This is a standard method for building from source.

```bash
cd ~/jq
autoreconf -i
./configure
make -j8
sudo make install
```

--------------------------------

### Subexpression Call by Relative Group Name Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Demonstrates calling a subexpression using its name and relative level adjustments.

```Regex
\g<name+level>
```

```Regex
\g<name-level>
```

--------------------------------

### Backreference by Relative Group Name Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Illustrates backreferencing a named group using its name and relative level adjustments.

```Regex
\k<name+level>
```

```Regex
\k<name-level>
```

--------------------------------

### Backreference by Relative Group Number Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Shows backreferencing a group using its relative number, adjusting for nesting levels.

```Regex
\k<n+level>
```

```Regex
\k<n-level>
```

--------------------------------

### Get Current Time

Source: https://github.com/jqlang/jq/wiki/jq-Language-Description

The `now` function returns the current time as a Unix timestamp. This is a side-effecting function as the output changes with each execution.

```jq
now
```

--------------------------------

### jq Module Imports, Includes, and Function Definitions

Source: https://github.com/jqlang/jq/wiki/jq-Language-Description

Demonstrates the structure for module imports, includes, and function definitions in a jq program, followed by the main expression.

```jq
# Module imports, includes, and function definitions:
import "a" as foo;
include "b";
def some_function: body_here;
# ...
#
# Finally, the main program, really, a singular expression:
some_expression | some_other_expression # and so on

# But note that you can have `def ...` in any expression.
```

--------------------------------

### Configure Bat for jq Syntax Highlighting

Source: https://github.com/jqlang/jq/wiki/bat-language-syntax

These commands set up Bat to recognize and highlight jq syntax. It involves creating a directory for custom syntaxes, instructing Bat to use a specific YAML file for the jq syntax definition, and then rebuilding Bat's cache. Finally, it demonstrates highlighting a simple jq expression.

```sh
$ mkdir -p "$(bat --config-dir)/syntaxes"
$ echo "paste below yaml into $(bat --config-dir)/syntaxes/jq.sublime-syntax"
$ bat cache --build
$ echo 'def f: 1+2;' | bat -p -l jq
```

--------------------------------

### Get unique keys from all objects in a list

Source: https://github.com/jqlang/jq/wiki/Cookbook

Extracts all unique top-level keys from all JSON objects within a given array.

```jq
[.. | objects | keys[]] | unique
```

--------------------------------

### Get Array Element with jv_array_get

Source: https://github.com/jqlang/jq/wiki/C-API:-jv

Demonstrates the standard usage of jv_array_get to retrieve an element from a jv array at a specific index.

```C
    jv elem = jv_array_get(array, 42);
```

--------------------------------

### List All jq Built-in Functions

Source: https://github.com/jqlang/jq/wiki/jq-Language-Description

Use this command to list all available built-in functions in jq. The output is a JSON array of function names.

```bash
jq -nr 'builtins[]'
```

--------------------------------

### Accessing Object Keys in jq 1.3

Source: https://github.com/jqlang/jq/wiki/FAQ

In jq 1.3, object keys are sorted by default. This example demonstrates how keys are processed.

```jq
jq -n '{b:1, a:2} | to_entries[].key'
```

--------------------------------

### Recursive Subexpression Call Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Demonstrates a left-most recursive call within a named group. This pattern is disallowed and will result in an error.

```Regex
(?<name>a|\g<name>b)
```

--------------------------------

### Subexpression Call by Relative Group Number Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Illustrates calling a subexpression using its relative group number, adjusting for nesting levels.

```Regex
\g<-n>
```

```Regex
\g<n+level>
```

```Regex
\g<n-level>
```

--------------------------------

### Valid Recursive Subexpression Call Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Illustrates a valid recursive call within a named group, where the recursive part is not the left-most alternative.

```Regex
(?<name>a|b\g<name>c)
```

--------------------------------

### Run jq with Docker

Source: https://github.com/jqlang/jq/blob/master/README.md

Extracts the version from a package.json file using Docker. Ensure the package.json file is accessible.

```bash
docker run --rm -i ghcr.io/jqlang/jq:latest < package.json '.version'
```

--------------------------------

### Array Slice in jq

Source: https://github.com/jqlang/jq/wiki/jq-Language-Description

Extracts a portion of an array based on start and end expressions. This operator allows for slicing arrays similar to Python.

```jq
term[start_expr : end_expr]
```

--------------------------------

### Collect Stream to Array in jq

Source: https://github.com/jqlang/jq/wiki/Advanced-Topics

Collects the output stream of an expression into an array. Useful for aggregating results. For example, `[range(.;.*2)]` collects integers.

```jq
[0,1]
```

```jq
[range(.;.*2)]
```

--------------------------------

### Create an array of n zeros using range and reduce

Source: https://github.com/jqlang/jq/wiki/FAQ

An alternative method to create an array of a specified size filled with zeros, utilizing `range` and `reduce`.

```jq
reduce range(0;n) as $i ([]; . + [0])
```

--------------------------------

### Convert Hjson to JSON with npm package

Source: https://github.com/jqlang/jq/wiki/FAQ

Install the hjson package globally via npm to convert Hjson files to JSON using the -j flag.

```bash
npm install hjson -g
hjson -j file.hjson # to convert to JSON
```

--------------------------------

### jq limit() with multiple limiters

Source: https://github.com/jqlang/jq/wiki/Advanced-Topics

Demonstrates a potentially surprising behavior of `limit()` when provided with multiple limit values, resulting in repeated outputs.

```jq
limit(1,2; range(0;10))
0
0
1
```

--------------------------------

### jq Template: Using $variables

Source: https://github.com/jqlang/jq/wiki/Cookbook

Instantiates a jq template file using '$'-variables. This method is suitable for a small number of variables and requires all variables to be explicitly provided.

```jsonc
{a: $a, b: $a}
```

```shell
jq -n --argjson a 0 -f ab.jq
```

--------------------------------

### jq 1.5+ Behavior with empty in reduce

Source: https://github.com/jqlang/jq/wiki/FAQ

This example shows the behavior of `empty` within a `reduce` statement, which might be surprising and could change in future versions.

```jq
jq -n 'reduce 2 as $x (3; empty)'
```

--------------------------------

### Negative Lookbehind with Shy Group Example

Source: https://github.com/jqlang/jq/wiki/Docs-for-Oniguruma-Regular-Expressions-(RE.txt)

Shows a negative lookbehind assertion that uses a non-capturing (shy) group. Captured groups are not allowed in negative lookbehinds.

```Regex
(?<!(?:subexp))
```

--------------------------------

### Import JSON into SQLite using jq

Source: https://github.com/jqlang/jq/wiki/FAQ

Illustrates importing JSON data into an SQLite table using the `sqlite3` CLI. It utilizes `.mode line`, `.separator "\t"`, and `.import` with jq's stream output for efficient data loading.

```bash
sqlite> create table input (
    json JSON
);
sqlite> .mode line
sqlite> .separator "\t"
sqlite> .import "|jq -c .[] input.json" input
sqlite> select * from input limit 1;
 json = {"key_one":1,"key_two":2,"key_three":3}
sqlite> 

```

--------------------------------

### Input Filename: Get Current Input File

Source: https://github.com/jqlang/jq/wiki/jq-Language-Description

The `input_filename` function returns the name of the file currently being processed. This is useful when dealing with multiple input files.

```jq
input_filename
```

--------------------------------

### Get Keys of Store Object

Source: https://github.com/jqlang/jq/wiki/For-JSONPath-users

This jq query retrieves the keys of the 'store' object, which are 'bicycle' and 'book'. This is used in conjunction with other queries to access elements by key.

```jq
.store | keys
```

--------------------------------

### Make jq script executable with shebang (Recommended)

Source: https://github.com/jqlang/jq/wiki/FAQ

This approach uses a shell script wrapper for jq scripts, ensuring portability across Unix-like systems. It correctly handles arguments and the script file itself.

```sh
#!/bin/sh --
# \
exec jq -Mf "$0" "$@"
# jq code follows
.your | .filter | .here
```