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TOC

jq can transform JSON in various ways, by selecting, iterating, reducing and otherwise mangling JSON documents. For instance, running the command jq ´map(.price) | add´ will take an array of JSON objects as input and return the sum of their "price" fields

jq can accept text input as well, but by default, jq reads a stream of JSON entities (including numbers and other literals) from stdin. Whitespace is only needed to separate entities such as 1 and 2, and true and false. One or more files may be specified, in which case jq will read input from those instead

OPTIONS

^

jq [options...] filter [files...]

  --version # Output the jq version and exit with zero
  --seq: # Use the application/json-seq MIME type scheme for separating JSON texts in jq´s input and output. This means that an ASCII RS (record separator) character is printed before each value on output and an ASCII LF (line feed) is printed after every output. Input JSON texts that fail to parse are ignored (but warned about), discarding all subsequent input until the next RS. This more also parses the output of jq without the --seq option
  --stream: # Parse the input in streaming fashion, outputing arrays of path and leaf values (scalars and empty arrays or empty objects). For example, "a" becomes [[],"a"], and [[],"a",["b"]] becomes [[0],[]], [[1],"a"], and [[1,0],"b"]
  -s, --slurp # Instead of running the filter for each JSON object in the input, read the entire input stream into a large array and run the filter just once
  -R, --raw-input # Don´t parse the input as JSON. Instead, each line of text is passed to the filter as a string. If combined with --slurp, then the entire input is passed to the filter as a single long string
  -n, --null-input # Don´t read any input at all! Instead, the filter is run once using null as the input. This is useful when using jq as a simple calculator or to construct JSON data from scratch
  -c, --compact-output # By default, jq pretty-prints JSON output. Using this option will result in more compact output by instead putting each JSON object on a single line
  --tab # Use a tab for each indentation level instead of two spaces
  --indent n # Use the given number of spaces (no more than 8) for indentation
  -M, --monochrome-output # disable color. By default, jq outputs colored JSON if writing to a terminal
  -C, --color-output # force color even if writing to a pipe
  -a, --ascii-output # jq usually outputs non-ASCII Unicode codepoints as UTF-8, even if the input specified them as escape sequences (like "\u03bc"). Using this option, you can force jq to produce pure ASCII output with every non-ASCII character replaced with the equivalent escape sequence
  --unbuffered # Flush the output after each JSON object is printed (useful if you´re piping a slow data source into jq and piping jq´s output elsewhere)
  -S, --sort-keys # Output the fields of each object with the keys in sorted order
  -r, --raw-output # With this option, if the filter´s result is a string then it will be written directly to standard output rather than being formatted as a JSON string with quotes. This can be useful for making jq filters talk to non-JSON-based systems
  -j, --join-output # Like -r but jq won´t print a newline after each output
  -f filename, --from-file filename # Read filter from the file rather than from a command line, like awk´s -f option. You can also use ´#´ to make comments
  -L directory # Prepend directory to the search list for modules. If this option is used then no builtin search list is used. See the section on modules below
  -e, --exit-status # Sets the exit status of jq to 0 if the last output values was neither false nor null, 1 if the last output value was either false or null, or 4 if no valid result was ever produced. Normally jq exits with 2 if there was any usage problem or system error, 3 if there was a jq program compile error, or 0 if the jq program ran
  --arg name value # This option passes a value to the jq program as a predefined variable. If you run jq with --arg foo bar, then $foo is available in the program and has the value "bar". Note that value will be treated as a string, so --arg foo 123 will bind $foo to "123"
  --argjson name JSON-text # This option passes a JSON-encoded value to the jq program as a predefined variable. If you run jq with --argjson foo 123, then $foo is available in the program and has the value 123
  --slurpfile variable-name filename # This option reads all the JSON texts in the named file and binds an array of the parsed JSON values to the given global variable. If you run jq with --argfile foo bar, then $foo is available in the program and has an array whose elements correspond to the texts in the file named bar
  --run-tests [filename] # Runs the tests in the given file or standard input. This must be the last option given and does not honor all preceding options. The input consists of comment lines, empty lines, and program lines followed by one input line, as many lines of output as are expected (one per output), and a terminating empty line. Compilation failure tests start with a line containing only "%%FAIL", then a line containing the program to compile, then a line containing an error message to compare to the actual

FORMAT

^

The @foo syntax is used to format and escape strings, which is useful for building URLs, documents in a language like HTML or XML, and so forth. @foo can be used as a filter on its own, the possible escapings are:

@text: # Calls tostring, see that function for details
@json: # Serializes the input as JSON
@html: # Applies HTML/XML escaping, by mapping the characters <>&´" to their entity equivalents <, >, &, &apos;, "
@uri: # Applies percent-encoding by mapping all reserved URI characters to a %XX sequence
@csv: # The input must be an array, and it is rendered as CSV with double quotes for strings, and quotes escaped by repetition
@tsv: # The input must be an array, and it is rendered as TSV (tab-separated values)
@sh: # The input is escaped suitable for use in a command-line for a POSIX shell
@base64: # The input is converted to base64 as specified by RFC 4648

BASIC FILTERS

^

.

The absolute simplest filter is . . This is a filter that takes its input and produces it unchanged as output. That is, this is the identity operator

  jq '.'
    "Hello, world!"
  => "Hello, world!"

.foo, .foo.bar

Object Identifier-Index. The simplest useful filter is .foo. When given a JSON object (aka dictionary or hash) as input, it produces the value at the key "foo", or null if there's none present. A filter of the form .foo.bar is equivalent to .foo|.bar

  jq '.foo'
    {"foo": 42, "bar": "less interesting data"}
  => 42

.foo? # Optional Object Identifier-Index. Just like .foo, but does not output even an error when . is not an array or an object

  jq '.foo?'
    {"foo": 42, "bar": "less interesting data"}
  => 42

  jq '.foo?'
    {"notfoo": true, "alsonotfoo": false}
  => null

.[<string>] # Generic Object Index. You  can  also  look up fields of an object using syntax like .["foo"] (.foo above is a shorthand version of this, but only for identifier-like strings).

  jq '.[0]'
    [{"name":"JSON", "good":true}, {"name":"XML", "good":false}]
  => {"name":"JSON", "good":true}

  jq '.[-2]'
    [1,2,3]
  => 2

.[10:15] # Array/String Slice. The .[10:15] syntax can be used to return a subarray of an array or substring of  a  string.  The  array  returned  by .[10:15]  will be of length 5, containing the elements from index 10 (inclusive) to index 15 (exclusive). Either index may be negative (in which case it counts backwards from the end of the array), or omitted (in which case it refers  to the start or end of the array)

  jq '.[2:4]'
    ["a","b","c","d","e"]
  => ["c", "d"]

  jq '.[2:4]'
    "abcdefghi"
  => "cd"

  jq '.[:3]'
    ["a","b","c","d","e"]
  => ["a", "b", "c"]

  jq '.[-2:]'
    ["a","b","c","d","e"]
  => ["d", "e"]

.[] # Array/Object Value Iterator. If  you  use the .[index] syntax, but omit the index entirely, it will return all of the elements of an array. Running .[] with the input [1,2,3] will produce the numbers as three separate results, rather than as a single array.

  jq '.[]'
    [{"name":"JSON", "good":true}, {"name":"XML", "good":false}]
  => {"name":"JSON", "good":true}, {"name":"XML", "good":false}

  jq '.[]'
    []
  =>

  jq '.[]'
    {"a": 1, "b": 1}
  => 1, 1

.[]? # Like .[], but no errors will be output if . is not an array or object

, # Comma. If two filters are separated by a comma, then the same input will be fed into both and the two filters'  output  value streams  will be concatenated in order: first, all of the outputs produced by the left expression, and then all of the outputs produced by the right. For instance, filter .foo, .bar, produces both the "foo" fields  and  "bar"  fields  as separate outputs

  jq '.foo, .bar'
    {"foo": 42, "bar": "something else", "baz": true}
  => 42, "something else"

  jq '.user, .projects[]'
    {"user":"stedolan", "projects": ["jq", "wikiflow"]}
  => "stedolan", "jq", "wikiflow"

  jq '.[4,2]'
    ["a","b","c","d","e"]
  => "e", "c"

\| # Pipe. The  |  operator combines two filters by feeding the output(s) of the one on the left into the input of the one on the right. It's pretty much the same as the Unix shell's pipe, if you're used to that

  jq '.[] | .name'
    [{"name":"JSON", "good":true}, {"name":"XML", "good":false}]
  => "JSON", "XML"

() # Parenthesis work as a grouping operator just as in any typical programming language

  jq '(. + 2) * 5'
    1
  => 15

TYPES AND VALUES

^

[] # Array construction. As  in  JSON,  [] is used to construct arrays, as in [1,2,3]. The elements of the arrays can be any jq expression, including a pipeline. All of the results produced by all of the expressions are collected into one big  array.  You  can use  it to construct an array out of a known quantity of values (as in [.foo, .bar, .baz]) or to "collect" all the results of a filter into an array (as in [.items[].name])

  jq '[.user, .projects[]]'
    {"user":"stedolan", "projects": ["jq", "wikiflow"]}
  => ["stedolan", "jq", "wikiflow"]

  jq '[ .[] | . * 2]'
    [1, 2, 3]
  => [2, 4, 6]

{} # Object Construction. Like JSON, {} is for constructing objects (aka dictionaries or hashes), as in: {"a": 42, "b": 17}. If  the keys are "identifier-like", then the quotes can be left off, as in {a:42, b:17}. Keys generated by expressions need to be parenthesized, e.g., {("a"+"b"):59}.

  jq '{user, title: .titles[]}'
    {"user":"stedolan","titles":["JQ Primer", "More JQ"]}
  => {"user":"stedolan", "title": "JQ Primer"}, {"user":"stedolan", "title": "More JQ"}

  jq '{(.user): .titles}'
    {"user":"stedolan","titles":["JQ Primer", "More JQ"]}
  => {"stedolan": ["JQ Primer", "More JQ"]}

.. # Recursive Descent. Recursively descends ., producing every value. This is the same as the zero-argument recurse builtin (see below). This is intended to resemble the XPath // operator. Note that ..a does not work; use ..|.a instead. In the example below we use ..|.a? to find all the values of object keys "a" in any object found "below" ..

  jq '..|.a?'
    [[{"a":1}]]
  => 1

BUILTIN OPERATORS AND FUNCTIONS

^

+ # Addition
  - Numbers are added by normal arithmetic.
  - Arrays are added by being concatenated into a larger array.
  - Strings are added by being joined into a larger string.
  - Objects are added by merging, that is, inserting all the key-value pairs from both objects into a single  combined object.  If  both  objects contain a value for the same key, the object on the right of the + wins

  jq '.a + 1'
    {"a": 7}
  => 8

  jq '.a + .b'
    {"a": [1,2], "b": [3,4]}
  => [1,2,3,4]

  jq '.a + null'
    {"a": 1}
  => 1

  jq '.a + 1'
    {}
  => 1

  jq '{a: 1} + {b: 2} + {c: 3} + {a: 42}'
    null
  => {"a": 42, "b": 2, "c": 3}

- # Subtraction. As well as normal arithmetic subtraction on numbers, the - operator can be used on arrays to remove all occurrences of the second array's elements from the first array.

       jq '4 - .a'
          {"a":3}
       => 1

       jq '. - ["xml", "yaml"]'
          ["xml", "yaml", "json"]
       => ["json"]

Multiplication, division, modulo: *, /, and %
   These  infix  operators  behave as expected when given two numbers. Division by zero raises an error. x % y computes x
   modulo y.

   Multiplying a string by a number produces the concatenation of that string that many times. "x" * 0 produces null.

   Dividing a string by another splits the first using the second as separators.

   Multiplying two objects will merge them recursively: this works like addition but if both objects contain a value  for
   the same key, and the values are objects, the two are merged with the same strategy.

       jq '10 / . * 3'
          5
       => 6

       jq '. / ", "'
          "a, b,c,d, e"
       => ["a","b,c,d","e"]

       jq '{"k": {"a": 1, "b": 2}} * {"k": {"a": 0,"c": 3}}'
          null
       => {"k": {"a": 0, "b": 2, "c": 3}}

       jq '.[] | (1 / .)?'
          [1,0,-1]
       => 1, -1

length
   The builtin function length gets the length of various different types of value:

  - The length of a string is the number of Unicode codepoints it contains (which will be the same as its JSON-encoded
       length in bytes if it's pure ASCII).

  - The length of an array is the number of elements.

  - The length of an object is the number of key-value pairs.

  - The length of null is zero.

       jq '.[] | length' [[1,2], "string", {"a":2}, null] => 2, 6, 1, 0

utf8bytelength
   The builtin function utf8bytelength outputs the number of bytes used to encode a string in UTF-8.

       jq 'utf8bytelength'
          "\u03bc"
       => 2

keys, keys_unsorted
   The builtin function keys, when given an object, returns its keys in an array.

   The keys are sorted "alphabetically", by unicode codepoint order. This is not an order that makes particular sense  in
   any particular language, but you can count on it being the same for any two objects with the same set of keys, regard‐
   less of locale settings.

   When keys is given an array, it returns the valid indices for that array: the integers from 0 to length-1.

   The keys_unsorted function is just like keys, but if the input is an object then the keys will not be sorted,  instead
   the keys will roughly be in insertion order.

       jq 'keys'
          {"abc": 1, "abcd": 2, "Foo": 3}
       => ["Foo", "abc", "abcd"]

       jq 'keys'
          [42,3,35]
       => [0,1,2]

has(key)
   The  builtin function has returns whether the input object has the given key, or the input array has an element at the
   given index.

   has($key) has the same effect as checking whether $key is a member of the array returned by keys, although has will be
   faster.

       jq 'map(has("foo"))'
          [{"foo": 42}, {}]
       => [true, false]

       jq 'map(has(2))'
          [[0,1], ["a","b","c"]]
       => [false, true]

in
   The builtin function in returns whether or not the input key is in the given object, or the input index corresponds to
   an element in the given array. It is, essentially, an inversed version of has.

       jq '.[] | in({"foo": 42})'
          ["foo", "bar"]
       => true, false

       jq 'map(in([0,1]))'
          [2, 0]
       => [false, true]

map(x), map_values(x)
   For any filter x, map(x) will run that filter for each element of the input array, and return the outputs in a new ar‐
   ray. map(.+1) will increment each element of an array of numbers.

   Similarly, map_values(x) will run that filter for each element, but it will return an object when an object is passed.

   map(x) is equivalent to [.[] | x]. In fact, this is how it's defined. Similarly, map_values(x) is defined as .[] |= x.

       jq 'map(.+1)'
          [1,2,3]
       => [2,3,4]

       jq 'map_values(.+1)'
          {"a": 1, "b": 2, "c": 3}
       => {"a": 2, "b": 3, "c": 4}

path(path_expression)
   Outputs  array  representations  of  the  given  path expression in .. The outputs are arrays of strings (object keys)
   and/or numbers (array indices).

   Path expressions are jq expressions like .a, but also .[]. There are two types of  path  expressions:  ones  that  can
   match exactly, and ones that cannot. For example, .a.b.c is an exact match path expression, while .a[].b is not.

   path(exact_path_expression)  will produce the array representation of the path expression even if it does not exist in
   ., if . is null or an array or an object.

   path(pattern) will produce array representations of the paths matching pattern if the paths exist in ..

   Note that the path expressions are not different from normal expressions. The  expression  path(..|select(type=="bool‐
   ean")) outputs all the paths to boolean values in ., and only those paths.

       jq 'path(.a[0].b)'
          null
       => ["a",0,"b"]

       jq '[path(..)]'
          {"a":[{"b":1}]}
       => [[],["a"],["a",0],["a",0,"b"]]

del(path_expression)
   The builtin function del removes a key and its corresponding value from an object.

       jq 'del(.foo)'
          {"foo": 42, "bar": 9001, "baz": 42}
       => {"bar": 9001, "baz": 42}

       jq 'del(.[1, 2])'
          ["foo", "bar", "baz"]
       => ["foo"]

getpath(PATHS)
   The builtin function getpath outputs the values in . found at each path in PATHS.

       jq 'getpath(["a","b"])'
          null
       => null

       jq '[getpath(["a","b"], ["a","c"])]'
          {"a":{"b":0, "c":1}}
       => [0, 1]

setpath(PATHS; VALUE)
   The builtin function setpath sets the PATHS in . to VALUE.

       jq 'setpath(["a","b"]; 1)'
          null
       => {"a": {"b": 1}}

       jq 'setpath(["a","b"]; 1)'
          {"a":{"b":0}}
       => {"a": {"b": 1}}

       jq 'setpath([0,"a"]; 1)'
          null
       => [{"a":1}]

delpaths(PATHS)
   The  builtin  function  delpaths  sets the PATHS in .. PATHS must be an array of paths, where each path is an array of
   strings and numbers.

       jq 'delpaths([["a","b"]])'
          {"a":{"b":1},"x":{"y":2}}
       => {"a":{},"x":{"y":2}}

to_entries, from_entries, with_entries
   These functions convert between an object and an array of key-value pairs. If to_entries is passed an object, then for
   each k: v entry in the input, the output array includes {"key": k, "value": v}.

   from_entries  does  the opposite conversion, and with_entries(foo) is a shorthand for to_entries | map(foo) | from_en‐
   tries, useful for doing some operation to all keys and values of an object. from_entries accepts key, Key, name, Name,
   value and Value as keys.

       jq 'to_entries'
          {"a": 1, "b": 2}
       => [{"key":"a", "value":1}, {"key":"b", "value":2}]

       jq 'from_entries'
          [{"key":"a", "value":1}, {"key":"b", "value":2}]
       => {"a": 1, "b": 2}

       jq 'with_entries(.key |= "KEY_" + .)'
          {"a": 1, "b": 2}
       => {"KEY_a": 1, "KEY_b": 2}

select(boolean_expression)
   The  function select(foo) produces its input unchanged if foo returns true for that input, and produces no output oth‐
   erwise.

   It's useful for filtering lists: [1,2,3] | map(select(. >= 2)) will give you [2,3].

       jq 'map(select(. >= 2))'
          [1,5,3,0,7]
       => [5,3,7]

       jq '.[] | select(.id == "second")'
          [{"id": "first", "val": 1}, {"id": "second", "val": 2}]
       => {"id": "second", "val": 2}

arrays, objects, iterables, booleans, numbers, normals, finites, strings, nulls, values, scalars
   These built-ins select only inputs that are arrays, objects, iterables (arrays or objects), booleans, numbers,  normal
   numbers, finite numbers, strings, null, non-null values, and non-iterables, respectively.

       jq '.[]|numbers'
          [[],{},1,"foo",null,true,false]
       => 1

empty
   empty returns no results. None at all. Not even null.

   It's useful on occasion. You'll know if you need it :)

       jq '1, empty, 2'
          null
       => 1, 2

       jq '[1,2,empty,3]'
          null
       => [1,2,3]

error(message)
   Produces an error, just like .a applied to values other than null and objects would, but with the given message as the
   error's value. Errors can be caught with try/catch; see below.

halt
   Stops the jq program with no further outputs. jq will exit with exit status 0.

halt_error, halt_error(exit_code)
   Stops the jq program with no further outputs. The input will be printed on stderr as raw output  (i.e.,  strings  will
   not have double quotes) with no decoration, not even a newline.

   The given exit_code (defaulting to 5) will be jq's exit status.

   For example, "Error: somthing went wrong\n"|halt_error(1).

$__loc__
   Produces  an  object  with  a "file" key and a "line" key, with the filename and line number where $__loc__ occurs, as
   values.

       jq 'try error("\($__loc__)") catch .'
          null
       => "{\"file\":\"<top-level>\",\"line\":1}"

paths, paths(node_filter), leaf_paths
   paths outputs the paths to all the elements in its input (except it does not output the empty list, representing . it‐
   self).

   paths(f) outputs the paths to any values for which f is true. That is, paths(numbers) outputs the paths to all numeric
   values.

   leaf_paths is an alias of paths(scalars); leaf_paths is deprecated and will be removed in the next major release.

       jq '[paths]'
          [1,[[],{"a":2}]]
       => [[0],[1],[1,0],[1,1],[1,1,"a"]]

       jq '[paths(scalars)]'
          [1,[[],{"a":2}]]
       => [[0],[1,1,"a"]]

add
   The filter add takes as input an array, and produces as output the elements of the array added  together.  This  might
   mean summed, concatenated or merged depending on the types of the elements of the input array - the rules are the same
   as those for the + operator (described above).

   If the input is an empty array, add returns null.

       jq 'add'
          ["a","b","c"]
       => "abc"

       jq 'add'
          [1, 2, 3]
       => 6

       jq 'add'
          []
       => null

any, any(condition), any(generator; condition)
   The filter any takes as input an array of boolean values, and produces true as output if any of the  elements  of  the
   array are true.

   If the input is an empty array, any returns false.

   The any(condition) form applies the given condition to the elements of the input array.

   The any(generator; condition) form applies the given condition to all the outputs of the given generator.

       jq 'any'
          [true, false]
       => true

       jq 'any'
          [false, false]
       => false

       jq 'any'
          []
       => false

all, all(condition), all(generator; condition)
   The  filter  all  takes as input an array of boolean values, and produces true as output if all of the elements of the
   array are true.

   The all(condition) form applies the given condition to the elements of the input array.

   The all(generator; condition) form applies the given condition to all the outputs of the given generator.

   If the input is an empty array, all returns true.

       jq 'all'
          [true, false]
       => false

       jq 'all'
          [true, true]
       => true

       jq 'all'
          []
       => true

flatten, flatten(depth)
   The filter flatten takes as input an array of nested arrays, and produces a flat array in which all arrays inside  the
   original array have been recursively replaced by their values. You can pass an argument to it to specify how many lev‐
   els of nesting to flatten.

   flatten(2) is like flatten, but going only up to two levels deep.

       jq 'flatten'
          [1, [2], [[3]]]
       => [1, 2, 3]

       jq 'flatten(1)'
          [1, [2], [[3]]]
       => [1, 2, [3]]

       jq 'flatten'
          [[]]
       => []

       jq 'flatten'
          [{"foo": "bar"}, [{"foo": "baz"}]]
       => [{"foo": "bar"}, {"foo": "baz"}]

range(upto), range(from;upto) range(from;upto;by)
   The range function produces a range of numbers. range(4;10) produces 6 numbers, from 4 (inclusive) to 10  (exclusive).
   The numbers are produced as separate outputs. Use [range(4;10)] to get a range as an array.

   The one argument form generates numbers from 0 to the given number, with an increment of 1.

   The two argument form generates numbers from from to upto with an increment of 1.

   The three argument form generates numbers from to upto with an increment of by.

       jq 'range(2;4)'
          null
       => 2, 3

       jq '[range(2;4)]'
          null
       => [2,3]

       jq '[range(4)]'
          null
       => [0,1,2,3]

       jq '[range(0;10;3)]'
          null
       => [0,3,6,9]

       jq '[range(0;10;-1)]'
          null
       => []

       jq '[range(0;-5;-1)]'
          null
       => [0,-1,-2,-3,-4]

floor
   The floor function returns the floor of its numeric input.

       jq 'floor'
          3.14159
       => 3

sqrt
   The sqrt function returns the square root of its numeric input.

       jq 'sqrt'
          9
       => 3

tonumber
   The  tonumber  function  parses  its  input  as a number. It will convert correctly-formatted strings to their numeric
   equivalent, leave numbers alone, and give an error on all other input.

       jq '.[] | tonumber'
          [1, "1"]
       => 1, 1

tostring
   The tostring function prints its input as a string. Strings are left unchanged, and all other values are JSON-encoded.

       jq '.[] | tostring'
          [1, "1", [1]]
       => "1", "1", "[1]"

type
   The type function returns the type of its argument as a string, which is one of null, boolean, number,  string,  array
   or object.

       jq 'map(type)'
          [0, false, [], {}, null, "hello"]
       => ["number", "boolean", "array", "object", "null", "string"]

infinite, nan, isinfinite, isnan, isfinite, isnormal
   Some  arithmetic  operations can yield infinities and "not a number" (NaN) values. The isinfinite builtin returns true
   if its input is infinite. The isnan builtin returns true if its input is a NaN. The infinite builtin returns  a  posi‐
   tive infinite value. The nan builtin returns a NaN. The isnormal builtin returns true if its input is a normal number.

   Note that division by zero raises an error.

   Currently most arithmetic operations operating on infinities, NaNs, and sub-normals do not raise errors.

       jq '.[] | (infinite * .) < 0'
          [-1, 1]
       => true, false

       jq 'infinite, nan | type'
          null
       => "number", "number"

sort, sort_by(path_expression)
   The sort functions sorts its input, which must be an array. Values are sorted in the following order:

  - null

  - false

  - true

  - numbers

  - strings, in alphabetical order (by unicode codepoint value)

  - arrays, in lexical order

  - objects

   The  ordering  for  objects  is a little complex: first they're compared by comparing their sets of keys (as arrays in
   sorted order), and if their keys are equal then the values are compared key by key.

   sort may be used to sort by a particular field of an object, or by applying any jq filter.

   sort_by(foo) compares two elements by comparing the result of foo on each element.

       jq 'sort'
          [8,3,null,6]
       => [null,3,6,8]

       jq 'sort_by(.foo)'
          [{"foo":4, "bar":10}, {"foo":3, "bar":100}, {"foo":2, "bar":1}]
       => [{"foo":2, "bar":1}, {"foo":3, "bar":100}, {"foo":4, "bar":10}]

group_by(path_expression)
   group_by(.foo) takes as input an array, groups the elements having the same .foo field into separate arrays, and  pro‐
   duces all of these arrays as elements of a larger array, sorted by the value of the .foo field.

   Any  jq  expression, not just a field access, may be used in place of .foo. The sorting order is the same as described
   in the sort function above.

       jq 'group_by(.foo)'
          [{"foo":1, "bar":10}, {"foo":3, "bar":100}, {"foo":1, "bar":1}]
       => [[{"foo":1, "bar":10}, {"foo":1, "bar":1}], [{"foo":3, "bar":100}]]

min, max, min_by(path_exp), max_by(path_exp)
   Find the minimum or maximum element of the input array.

   The min_by(path_exp) and max_by(path_exp) functions allow you to specify a particular field or  property  to  examine,
   e.g. min_by(.foo) finds the object with the smallest foo field.

       jq 'min'
          [5,4,2,7]
       => 2

       jq 'max_by(.foo)'
          [{"foo":1, "bar":14}, {"foo":2, "bar":3}]
       => {"foo":2, "bar":3}

unique, unique_by(path_exp)
   The  unique  function takes as input an array and produces an array of the same elements, in sorted order, with dupli‐
   cates removed.

   The unique_by(path_exp) function will keep only one element for each value obtained by applying the argument. Think of
   it as making an array by taking one element out of every group produced by group.

       jq 'unique'
          [1,2,5,3,5,3,1,3]
       => [1,2,3,5]

       jq 'unique_by(.foo)'
          [{"foo": 1, "bar": 2}, {"foo": 1, "bar": 3}, {"foo": 4, "bar": 5}]
       => [{"foo": 1, "bar": 2}, {"foo": 4, "bar": 5}]

       jq 'unique_by(length)'
          ["chunky", "bacon", "kitten", "cicada", "asparagus"]
       => ["bacon", "chunky", "asparagus"]

reverse
   This function reverses an array.

       jq 'reverse'
          [1,2,3,4]
       => [4,3,2,1]

contains(element)
   The  filter  contains(b) will produce true if b is completely contained within the input. A string B is contained in a
   string A if B is a substring of A. An array B is contained in an array A if all elements in B are contained in any el‐
   ement  in  A.  An object B is contained in object A if all of the values in B are contained in the value in A with the
   same key. All other types are assumed to be contained in each other if they are equal.

       jq 'contains("bar")'
          "foobar"
       => true

       jq 'contains(["baz", "bar"])'
          ["foobar", "foobaz", "blarp"]
       => true

       jq 'contains(["bazzzzz", "bar"])'
          ["foobar", "foobaz", "blarp"]
       => false

       jq 'contains({foo: 12, bar: [{barp: 12}]})'
          {"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]}
       => true

       jq 'contains({foo: 12, bar: [{barp: 15}]})'
          {"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]}
       => false

indices(s)
   Outputs an array containing the indices in . where s occurs. The input may be an array, in which case if s is an array
   then the indices output will be those where all elements in . match those of s.

       jq 'indices(", ")'
          "a,b, cd, efg, hijk"
       => [3,7,12]

       jq 'indices(1)'
          [0,1,2,1,3,1,4]
       => [1,3,5]

       jq 'indices([1,2])'
          [0,1,2,3,1,4,2,5,1,2,6,7]
       => [1,8]

index(s), rindex(s)
   Outputs the index of the first (index) or last (rindex) occurrence of s in the input.

       jq 'index(", ")'
          "a,b, cd, efg, hijk"
       => 3

       jq 'rindex(", ")'
          "a,b, cd, efg, hijk"
       => 12

inside
   The  filter inside(b) will produce true if the input is completely contained within b. It is, essentially, an inversed
   version of contains.

       jq 'inside("foobar")'
          "bar"
       => true

       jq 'inside(["foobar", "foobaz", "blarp"])'
          ["baz", "bar"]
       => true

       jq 'inside(["foobar", "foobaz", "blarp"])'
          ["bazzzzz", "bar"]
       => false

       jq 'inside({"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]})'
          {"foo": 12, "bar": [{"barp": 12}]}
       => true

       jq 'inside({"foo": 12, "bar":[1,2,{"barp":12, "blip":13}]})'
          {"foo": 12, "bar": [{"barp": 15}]}
       => false

startswith(str)
   Outputs true if . starts with the given string argument.

       jq '[.[]|startswith("foo")]'
          ["fo", "foo", "barfoo", "foobar", "barfoob"]
       => [false, true, false, true, false]

endswith(str)
   Outputs true if . ends with the given string argument.

       jq '[.[]|endswith("foo")]'
          ["foobar", "barfoo"]
       => [false, true]

combinations, combinations(n)
   Outputs all combinations of the elements of the arrays in the input array. If given an argument n, it outputs all com‐
   binations of n repetitions of the input array.

       jq 'combinations'
          [[1,2], [3, 4]]
       => [1, 3], [1, 4], [2, 3], [2, 4]

       jq 'combinations(2)'
          [0, 1]
       => [0, 0], [0, 1], [1, 0], [1, 1]

ltrimstr(str)
   Outputs its input with the given prefix string removed, if it starts with it.

       jq '[.[]|ltrimstr("foo")]'
          ["fo", "foo", "barfoo", "foobar", "afoo"]
       => ["fo","","barfoo","bar","afoo"]

rtrimstr(str)
   Outputs its input with the given suffix string removed, if it ends with it.

       jq '[.[]|rtrimstr("foo")]'
          ["fo", "foo", "barfoo", "foobar", "foob"]
       => ["fo","","bar","foobar","foob"]

explode
   Converts an input string into an array of the string's codepoint numbers.

       jq 'explode'
          "foobar"
       => [102,111,111,98,97,114]

implode
   The inverse of explode.

       jq 'implode'
          [65, 66, 67]
       => "ABC"

split(str)
   Splits an input string on the separator argument.

       jq 'split(", ")'
          "a, b,c,d, e, "
       => ["a","b,c,d","e",""]

join(str)
   Joins the array of elements given as input, using the argument as separator. It is the inverse of split: that is, run‐
   ning split("foo") | join("foo") over any input string returns said input string.

   Numbers and booleans in the input are converted to strings. Null values are treated as empty strings. Arrays  and  ob‐
   jects in the input are not supported.

       jq 'join(", ")'
          ["a","b,c,d","e"]
       => "a, b,c,d, e"

       jq 'join(" ")'
          ["a",1,2.3,true,null,false]
       => "a 1 2.3 true  false"

ascii_downcase, ascii_upcase
   Emit a copy of the input string with its alphabetic characters (a-z and A-Z) converted to the specified case.

while(cond; update)
   The while(cond; update) function allows you to repeatedly apply an update to . until cond is false.

   Note  that while(cond; update) is internally defined as a recursive jq function. Recursive calls within while will not
   consume additional memory if update produces at most one output for each input. See advanced topics below.

       jq '[while(.<100; .*2)]'
          1
       => [1,2,4,8,16,32,64]

until(cond; next)
   The until(cond; next) function allows you to repeatedly apply the expression next, initially to . then to its own out‐
   put, until cond is true. For example, this can be used to implement a factorial function (see below).

   Note  that until(cond; next) is internally defined as a recursive jq function. Recursive calls within until() will not
   consume additional memory if next produces at most one output for each input. See advanced topics below.

       jq '[.,1]|until(.[0] < 1; [.[0] - 1, .[1] * .[0]])|.[1]'
          4
       => 24

recurse(f), recurse, recurse(f; condition), recurse_down
   The recurse(f) function allows you to search through a recursive structure, and extract interesting data from all lev‐
   els. Suppose your input represents a filesystem:

       {"name": "/", "children": [
         {"name": "/bin", "children": [
           {"name": "/bin/ls", "children": []},
           {"name": "/bin/sh", "children": []}]},
         {"name": "/home", "children": [
           {"name": "/home/stephen", "children": [
             {"name": "/home/stephen/jq", "children": []}]}]}]}

   Now  suppose  you  want  to extract all of the filenames present. You need to retrieve .name, .children[].name, .chil‐
   dren[].children[].name, and so on. You can do this with:

       recurse(.children[]) | .name

   When called without an argument, recurse is equivalent to recurse(.[]?).

   recurse(f) is identical to recurse(f; . != null) and can be used without concerns about recursion depth.

   recurse(f; condition) is a generator which begins by emitting . and then emits in turn .|f,  .|f|f,  .|f|f|f,  ...  so
   long  as the computed value satisfies the condition. For example, to generate all the integers, at least in principle,
   one could write recurse(.+1; true).

   For legacy reasons, recurse_down exists as an alias to calling recurse without arguments.  This  alias  is  considered
   deprecated and will be removed in the next major release.

   The recursive calls in recurse will not consume additional memory whenever f produces at most a single output for each
   input.

       jq 'recurse(.foo[])'
          {"foo":[{"foo": []}, {"foo":[{"foo":[]}]}]}
       => {"foo":[{"foo":[]},{"foo":[{"foo":[]}]}]}, {"foo":[]}, {"foo":[{"foo":[]}]}, {"foo":[]}

       jq 'recurse'
          {"a":0,"b":[1]}
       => {"a":0,"b":[1]}, 0, [1], 1

       jq 'recurse(. * .; . < 20)'
          2
       => 2, 4, 16

walk(f)
   The walk(f) function applies f recursively to every component of the input entity. When an array is encountered, f  is
   first  applied  to its elements and then to the array itself; when an object is encountered, f is first applied to all
   the values and then to the object. In practice, f will usually test the type of its input, as illustrated in the  fol‐
   lowing  examples.  The first example highlights the usefulness of processing the elements of an array of arrays before
   processing the array itself. The second example shows how all the keys of all the objects within the input can be con‐
   sidered for alteration.

       jq 'walk(if type == "array" then sort else . end)'
          [[4, 1, 7], [8, 5, 2], [3, 6, 9]]
       => [[1,4,7],[2,5,8],[3,6,9]]

       jq 'walk( if type == "object" then with_entries( .key |= sub( "^_+"; "") ) else . end )'
          [ { "_a": { "__b": 2 } } ]
       => [{"a":{"b":2}}]

$ENV, env
   $ENV is an object representing the environment variables as set when the jq program started.

   env outputs an object representing jq's current environment.

   At the moment there is no builtin for setting environment variables.

       jq '$ENV.PAGER'
          null
       => "less"

       jq 'env.PAGER'
          null
       => "less"

transpose
   Transpose  a possibly jagged matrix (an array of arrays). Rows are padded with nulls so the result is always rectangu‐
   lar.

       jq 'transpose'
          [[1], [2,3]]
       => [[1,2],[null,3]]

bsearch(x)
   bsearch(x) conducts a binary search for x in the input array. If the input is sorted and contains x,  then  bsearch(x)
   will  return its index in the array; otherwise, if the array is sorted, it will return (-1 - ix) where ix is an inser‐
   tion point such that the array would still be sorted after the insertion of x at ix.  If  the  array  is  not  sorted,
   bsearch(x) will return an integer that is probably of no interest.

       jq 'bsearch(0)'
          [0,1]
       => 0

       jq 'bsearch(0)'
          [1,2,3]
       => -1

       jq 'bsearch(4) as $ix | if $ix < 0 then .[-(1+$ix)] = 4 else . end'
          [1,2,3]
       => [1,2,3,4]

String interpolation - \(foo)
   Inside  a  string,  you can put an expression inside parens after a backslash. Whatever the expression returns will be
   interpolated into the string.

       jq '"The input was \(.), which is one less than \(.+1)"'
          42
       => "The input was 42, which is one less than 43"

Convert to/from JSON
   The tojson and fromjson builtins dump values as JSON texts or parse JSON texts into values, respectively.  The  tojson
   builtin  differs  from  tostring  in  that  tostring  returns strings unmodified, while tojson encodes strings as JSON
   strings.

       jq '[.[]|tostring]'
          [1, "foo", ["foo"]]
       => ["1","foo","[\"foo\"]"]

       jq '[.[]|tojson]'
          [1, "foo", ["foo"]]
       => ["1","\"foo\"","[\"foo\"]"]

       jq '[.[]|tojson|fromjson]'
          [1, "foo", ["foo"]]
       => [1,"foo",["foo"]]

Format strings and escaping
   The @foo syntax is used to format and escape strings, which is useful for building URLs, documents in a language  like
   HTML or XML, and so forth. @foo can be used as a filter on its own, the possible escapings are:

   @text:

          Calls tostring, see that function for details.

   @json:

          Serializes the input as JSON.

   @html:

          Applies  HTML/XML  escaping,  by  mapping  the  characters <>&'" to their entity equivalents <, >, &,
          &apos;, ".

   @uri:

          Applies percent-encoding, by mapping all reserved URI characters to a %XX sequence.

   @csv:

          The input must be an array, and it is rendered as CSV with double quotes for strings,  and  quotes  escaped  by
          repetition.

   @tsv:

          The  input must be an array, and it is rendered as TSV (tab-separated values). Each input array will be printed
          as a single line. Fields are separated by a single tab (ascii 0x09). Input characters line-feed  (ascii  0x0a),
          carriage-return  (ascii  0x0d),  tab (ascii 0x09) and backslash (ascii 0x5c) will be output as escape sequences
          \n, \r, \t, \\ respectively.

   @sh:

          The input is escaped suitable for use in a command-line for a POSIX shell. If the input is an array, the output
          will be a series of space-separated strings.

   @base64:

          The input is converted to base64 as specified by RFC 4648.

   @base64d:

          The  inverse  of  @base64, input is decoded as specified by RFC 4648. Note: If the decoded string is not UTF-8,
          the results are undefined.

   This syntax can be combined with string interpolation in a useful way. You can follow a @foo token with a string  lit‐
   eral. The contents of the string literal will not be escaped. However, all interpolations made inside that string lit‐
   eral will be escaped. For instance,

       @uri "https://www.google.com/search?q=\(.search)"

   will produce the following output for the input {"search":"what is jq?"}:

       "https://www.google.com/search?q=what%20is%20jq%3F"

   Note that the slashes, question mark, etc. in the URL are not escaped, as they were part of the string literal.

       jq '@html'
          "This works if x < y"
       => "This works if x < y"

       jq '@sh "echo \(.)"'
          "O'Hara's Ale"
       => "echo 'O'\\''Hara'\\''s Ale'"

       jq '@base64'
          "This is a message"
       => "VGhpcyBpcyBhIG1lc3NhZ2U="

       jq '@base64d'
          "VGhpcyBpcyBhIG1lc3NhZ2U="
       => "This is a message"

Dates
   jq provides some basic date handling functionality, with some high-level and low-level builtins. In  all  cases  these
   builtins deal exclusively with time in UTC.

   The  fromdateiso8601  builtin  parses  datetimes  in  the  ISO 8601 format to a number of seconds since the Unix epoch
   (1970-01-01T00:00:00Z). The todateiso8601 builtin does the inverse.

   The fromdate builtin parses datetime strings. Currently fromdate only supports ISO 8601 datetime strings, but  in  the
   future it will attempt to parse datetime strings in more formats.

   The todate builtin is an alias for todateiso8601.

   The now builtin outputs the current time, in seconds since the Unix epoch.

   Low-level  jq interfaces to the C-library time functions are also provided: strptime, strftime, strflocaltime, mktime,
   gmtime, and localtime. Refer to your host operating system's documentation for the format strings used by strptime and
   strftime.  Note:  these are not necessarily stable interfaces in jq, particularly as to their localization functional‐
   ity.

   The gmtime builtin consumes a number of seconds since the Unix epoch and outputs a "broken down  time"  representation
   of Greenwhich Meridian time as an array of numbers representing (in this order): the year, the month (zero-based), the
   day of the month (one-based), the hour of the day, the minute of the hour, the second of the minute, the  day  of  the
   week,  and  the  day  of the year -- all one-based unless otherwise stated. The day of the week number may be wrong on
   some systems for dates before March 1st 1900, or after December 31 2099.

   The localtime builtin works like the gmtime builtin, but using the local timezone setting.

   The mktime builtin consumes "broken down time" representations of time output by gmtime and strptime.

   The strptime(fmt) builtin parses input strings matching the fmt argument. The output is in the "broken down time" rep‐
   resentation consumed by gmtime and output by mktime.

   The  strftime(fmt)  builtin formats a time (GMT) with the given format. The strflocaltime does the same, but using the
   local timezone setting.

   The format strings for strptime and strftime are described in typical C library documentation. The format  string  for
   ISO 8601 datetime is "%Y-%m-%dT%H:%M:%SZ".

   jq may not support some or all of this date functionality on some systems. In particular, the %u and %j specifiers for
   strptime(fmt) are not supported on macOS.

       jq 'fromdate'
          "2015-03-05T23:51:47Z"
       => 1425599507

       jq 'strptime("%Y-%m-%dT%H:%M:%SZ")'
          "2015-03-05T23:51:47Z"
       => [2015,2,5,23,51,47,4,63]

       jq 'strptime("%Y-%m-%dT%H:%M:%SZ")|mktime'
          "2015-03-05T23:51:47Z"
       => 1425599507

SQL-Style Operators
   jq provides a few SQL-style operators.

   INDEX(stream; index_expression):

          This builtin produces an object whose keys are computed by the given index expression  applied  to  each  value
          from the given stream.

   JOIN($idx; stream; idx_expr; join_expr):

          This builtin joins the values from the given stream to the given index. The index's keys are computed by apply‐
          ing the given index expression to each value from the given stream. An array of the value in the stream and the
          corresponding value from the index is fed to the given join expression to produce each result.

   JOIN($idx; stream; idx_expr):

          Same as JOIN($idx; stream; idx_expr; .).

   JOIN($idx; idx_expr):

          This  builtin joins the input . to the given index, applying the given index expression to . to compute the in‐
          dex key. The join operation is as described above.

   IN(s):

          This builtin outputs true if . appears in the given stream, otherwise it outputs false.

   IN(source; s):

          This builtin outputs true if any value in the source stream appears in the second stream, otherwise it  outputs
          false.

builtins
   Returns a list of all builtin functions in the format name/arity. Since functions with the same name but different ar‐
   ities are considered separate functions, all/0, all/1, and all/2 would all be present in the list.

CONDITIONALS AND COMPARISONS
==, !=
   The expression 'a == b' will produce 'true' if the result of a and b are equal (that is, if they represent  equivalent
   JSON  documents) and 'false' otherwise. In particular, strings are never considered equal to numbers. If you're coming
   from Javascript, jq's == is like Javascript's === - considering values equal only when they have the same type as well
   as the same value.

   != is "not equal", and 'a != b' returns the opposite value of 'a == b'

       jq '.[] == 1'
          [1, 1.0, "1", "banana"]
       => true, true, false, false

if-then-else
   if  A  then  B else C end will act the same as B if A produces a value other than false or null, but act the same as C
   otherwise.

   Checking for false or null is a simpler notion of "truthiness" than is found in Javascript or  Python,  but  it  means
   that  you'll sometimes have to be more explicit about the condition you want: you can't test whether, e.g. a string is
   empty using if .name then A else B end, you'll need something more like if (.name | length) > 0 then A else B end  in‐
   stead.

   If  the condition A produces multiple results, then B is evaluated once for each result that is not false or null, and
   C is evaluated once for each false or null.

   More cases can be added to an if using elif A then B syntax.

       jq 'if . == 0 then

   "zero" elif . == 1 then "one" else "many" end' 2 => "many"

>, >=, <=, <
   The comparison operators >, >=, <=, < return whether their left argument is greater than, greater than  or  equal  to,
   less than or equal to or less than their right argument (respectively).

   The ordering is the same as that described for sort, above.

       jq '. < 5'
          2
       => true

and/or/not
   jq  supports  the  normal Boolean operators and/or/not. They have the same standard of truth as if expressions - false
   and null are considered "false values", and anything else is a "true value".

   If an operand of one of these operators produces multiple results, the operator itself will produce a result for  each
   input.

   not  is  in  fact a builtin function rather than an operator, so it is called as a filter to which things can be piped
   rather than with special syntax, as in .foo and .bar | not.

   These three only produce the values "true" and "false", and so are only useful for genuine Boolean operations,  rather
   than  the  common Perl/Python/Ruby idiom of "value_that_may_be_null or default". If you want to use this form of "or",
   picking between two values rather than evaluating a condition, see the "//" operator below.

       jq '42 and "a string"'
          null
       => true

       jq '(true, false) or false'
          null
       => true, false

       jq '(true, true) and (true, false)'
          null
       => true, false, true, false

       jq '[true, false | not]'
          null
       => [false, true]

Alternative operator: //
   A filter of the form a // b produces the same results as a, if a produces results other than false  and  null.  Other‐
   wise, a // b produces the same results as b.

   This is useful for providing defaults: .foo // 1 will evaluate to 1 if there's no .foo element in the input. It's sim‐
   ilar to how or is sometimes used in Python (jq's or operator is reserved for strictly Boolean operations).

       jq '.foo // 42'
          {"foo": 19}
       => 19

       jq '.foo // 42'
          {}
       => 42

try-catch
   Errors can be caught by using try EXP catch EXP. The first expression is executed, and if it fails then the second  is
   executed  with the error message. The output of the handler, if any, is output as if it had been the output of the ex‐
   pression to try.

   The try EXP form uses empty as the exception handler.

       jq 'try .a catch ". is not an object"'
          true
       => ". is not an object"

       jq '[.[]|try .a]'
          [{}, true, {"a":1}]
       => [null, 1]

       jq 'try error("some exception") catch .'
          true
       => "some exception"

Breaking out of control structures
   A convenient use of try/catch is to break out of control structures like reduce, foreach, while, and so on.

   For example:

       # Repeat an expression until it raises "break" as an
       # error, then stop repeating without re-raising the error.
       # But if the error caught is not "break" then re-raise it.
       try repeat(exp) catch .=="break" then empty else error;

   jq has a syntax for named lexical labels to "break" or "go (back) to":

       label $out | ... break $out ...

   The break $label_name expression will cause the program to to act as though the  nearest  (to  the  left)  label  $la‐
   bel_name produced empty.

   The relationship between the break and corresponding label is lexical: the label has to be "visible" from the break.

   To break out of a reduce, for example:

       label $out | reduce .[] as $item (null; if .==false then break $out else ... end)

   The following jq program produces a syntax error:

       break $out

   because no label $out is visible.

Error Suppression / Optional Operator: ?
   The ? operator, used as EXP?, is shorthand for try EXP.

       jq '[.[]|(.a)?]'
          [{}, true, {"a":1}]
       => [null, 1]

REGULAR EXPRESSIONS (PCRE)
   jq  uses  the  Oniguruma  regular expression library, as do php, ruby, TextMate, Sublime Text, etc, so the description
   here will focus on jq specifics.

   The jq regex filters are defined so that they can be used using one of these patterns:

       STRING | FILTER( REGEX )
       STRING | FILTER( REGEX; FLAGS )
       STRING | FILTER( [REGEX] )
       STRING | FILTER( [REGEX, FLAGS] )

   where: * STRING, REGEX and FLAGS are jq strings and subject to jq string interpolation; * REGEX, after string interpo‐
   lation, should be a valid PCRE regex; * FILTER is one of test, match, or capture, as described below.

   FLAGS is a string consisting of one of more of the supported flags:

  - g - Global search (find all matches, not just the first)

  - i - Case insensitive search

  - m - Multi line mode ('.' will match newlines)

  - n - Ignore empty matches

  - p - Both s and m modes are enabled

  - s - Single line mode ('^' -> '\A', '$' -> '\Z')

  - l - Find longest possible matches

  - x - Extended regex format (ignore whitespace and comments)

   To match whitespace in an x pattern use an escape such as \s, e.g.

  - test( "a\sb", "x" ).

   Note that certain flags may also be specified within REGEX, e.g.

  - jq -n '("test", "TEst", "teST", "TEST") | test( "(?i)te(?-i)st" )'

   evaluates to: true, true, false, false.

test(val), test(regex; flags)
   Like match, but does not return match objects, only true or false for whether or not the regex matches the input.

       jq 'test("foo")'
          "foo"
       => true

       jq '.[] | test("a b c # spaces are ignored"; "ix")'
          ["xabcd", "ABC"]
       => true, true

match(val), match(regex; flags)
   match outputs an object for each match it finds. Matches have the following fields:

  - offset - offset in UTF-8 codepoints from the beginning of the input

  - length - length in UTF-8 codepoints of the match

  - string - the string that it matched

  - captures - an array of objects representing capturing groups.

   Capturing group objects have the following fields:

  - offset - offset in UTF-8 codepoints from the beginning of the input

  - length - length in UTF-8 codepoints of this capturing group

  - string - the string that was captured

  - name - the name of the capturing group (or null if it was unnamed)

   Capturing groups that did not match anything return an offset of -1

       jq 'match("(abc)+"; "g")'
          "abc abc"
       => {"offset": 0, "length": 3, "string": "abc", "captures": [{"offset": 0, "length": 3, "string": "abc", "name": null}]}, {"offset": 4, "length": 3, "string": "abc", "captures": [{"offset": 4, "length": 3, "string": "abc", "name": null}]}

       jq 'match("foo")'
          "foo bar foo"
       => {"offset": 0, "length": 3, "string": "foo", "captures": []}

       jq 'match(["foo", "ig"])'
          "foo bar FOO"
       => {"offset": 0, "length": 3, "string": "foo", "captures": []}, {"offset": 8, "length": 3, "string": "FOO", "captures": []}

       jq 'match("foo (?<bar123>bar)? foo"; "ig")'
          "foo bar foo foo  foo"
       => {"offset": 0, "length": 11, "string": "foo bar foo", "captures": [{"offset": 4, "length": 3, "string": "bar", "name": "bar123"}]}, {"offset": 12, "length": 8, "string": "foo  foo", "captures": [{"offset": -1, "length": 0, "string": null, "name": "bar123"}]}

       jq '[ match("."; "g")] | length'
          "abc"
       => 3

capture(val), capture(regex; flags)
   Collects  the named captures in a JSON object, with the name of each capture as the key, and the matched string as the
   corresponding value.

       jq 'capture("(?<a>[a-z]+)-(?<n>[0-9]+)")'
          "xyzzy-14"
       => { "a": "xyzzy", "n": "14" }

scan(regex), scan(regex; flags)
   Emit a stream of the non-overlapping substrings of the input that match the regex in accordance with the flags, if any
   have  been specified. If there is no match, the stream is empty. To capture all the matches for each input string, use
   the idiom [ expr ], e.g. [ scan(regex) ].

split(regex; flags)
   For backwards compatibility, split splits on a string, not a regex.

splits(regex), splits(regex; flags)
   These provide the same results as their split counterparts, but as a stream instead of an array.

sub(regex; tostring) sub(regex; string; flags)
   Emit the string obtained by replacing the first match of regex in the input string with tostring, after interpolation.
   tostring  should be a jq string, and may contain references to named captures. The named captures are, in effect, pre‐
   sented as a JSON object (as constructed by capture) to tostring, so a reference to a captured variable named "x" would
   take the form: "(.x)".

gsub(regex; string), gsub(regex; string; flags)
   gsub is like sub but all the non-overlapping occurrences of the regex are replaced by the string, after interpolation.

ADVANCED FEATURES
   Variables  are  an absolute necessity in most programming languages, but they're relegated to an "advanced feature" in
   jq.

   In most languages, variables are the only means of passing around data. If you calculate a value, and you want to  use
   it  more than once, you'll need to store it in a variable. To pass a value to another part of the program, you'll need
   that part of the program to define a variable (as a function parameter, object member, or whatever) in which to  place
   the data.

   It  is also possible to define functions in jq, although this is is a feature whose biggest use is defining jq's stan‐
   dard library (many jq functions such as map and find are in fact written in jq).

   jq has reduction operators, which are very powerful but a bit tricky. Again, these are mostly used internally, to  de‐
   fine some useful bits of jq's standard library.

   It  may  not be obvious at first, but jq is all about generators (yes, as often found in other languages). Some utili‐
   ties are provided to help deal with generators.

   Some minimal I/O support (besides reading JSON from standard input, and writing JSON to standard output) is available.

   Finally, there is a module/library system.

Variable / Symbolic Binding Operator: ... as $identifier | ...
   In jq, all filters have an input and an output, so manual plumbing is not necessary to pass a value from one part of a
   program to the next. Many expressions, for instance a + b, pass their input to two distinct subexpressions (here a and
   b are both passed the same input), so variables aren't usually necessary in order to use a value twice.

   For instance, calculating the average value of an array of numbers requires a few variables in  most  languages  -  at
   least one to hold the array, perhaps one for each element or for a loop counter. In jq, it's simply add / length - the
   add expression is given the array and produces its sum, and the length expression is given the array and produces  its
   length.

   So,  there's  generally  a  cleaner way to solve most problems in jq than defining variables. Still, sometimes they do
   make things easier, so jq lets you define variables using expression as $variable. All variable names  start  with  $.
   Here's a slightly uglier version of the array-averaging example:

       length as $array_length | add / $array_length

   We'll need a more complicated problem to find a situation where using variables actually makes our lives easier.

   Suppose  we have an array of blog posts, with "author" and "title" fields, and another object which is used to map au‐
   thor usernames to real names. Our input looks like:

       {"posts": [{"title": "Frist psot", "author": "anon"},
                  {"title": "A well-written article", "author": "person1"}],
        "realnames": {"anon": "Anonymous Coward",
                      "person1": "Person McPherson"}}

   We want to produce the posts with the author field containing a real name, as in:

       {"title": "Frist psot", "author": "Anonymous Coward"}
       {"title": "A well-written article", "author": "Person McPherson"}

   We use a variable, $names, to store the realnames object, so that we can refer to it  later  when  looking  up  author
   usernames:

       .realnames as $names | .posts[] | {title, author: $names[.author]}

   The  expression  exp as $x | ... means: for each value of expression exp, run the rest of the pipeline with the entire
   original input, and with $x set to that value. Thus as functions as something of a foreach loop.

   Just as {foo} is a handy way of writing {foo: .foo}, so {$foo} is a handy way of writing {foo:$foo}.

   Multiple variables may be declared using a single as expression by providing a pattern that matches the  structure  of
   the input (this is known as "destructuring"):

       . as {realnames: $names, posts: [$first, $second]} | ...

   The  variable  declarations in array patterns (e.g., . as [$first, $second]) bind to the elements of the array in from
   the element at index zero on up, in order. When there is no value at the index for an array pattern element,  null  is
   bound to that variable.

   Variables are scoped over the rest of the expression that defines them, so

       .realnames as $names | (.posts[] | {title, author: $names[.author]})

   will work, but

       (.realnames as $names | .posts[]) | {title, author: $names[.author]}

   won't.

   For programming language theorists, it's more accurate to say that jq variables are lexically-scoped bindings. In par‐
   ticular there's no way to change the value of a binding; one can only setup a new binding  with  the  same  name,  but
   which will not be visible where the old one was.

       jq '.bar as $x | .foo | . + $x'
          {"foo":10, "bar":200}
       => 210

       jq '. as $i|[(.*2|. as $i| $i), $i]'
          5
       => [10,5]

       jq '. as [$a, $b, {c: $c}] | $a + $b + $c'
          [2, 3, {"c": 4, "d": 5}]
       => 9

       jq '.[] as [$a, $b] | {a: $a, b: $b}'
          [[0], [0, 1], [2, 1, 0]]
       => {"a":0,"b":null}, {"a":0,"b":1}, {"a":2,"b":1}

Defining Functions
   You can give a filter a name using "def" syntax:

       def increment: . + 1;

   From  then on, increment is usable as a filter just like a builtin function (in fact, this is how many of the builtins
   are defined). A function may take arguments:

       def map(f): [.[] | f];

   Arguments are passed as filters (functions with no arguments), not as values. The same argument may be referenced mul‐
   tiple  times  with  different inputs (here f is run for each element of the input array). Arguments to a function work
   more like callbacks than like value arguments. This is important to understand. Consider:

       def foo(f): f|f;
       5|foo(.*2)

   The result will be 20 because f is .*2, and during the first invocation of f . will be 5, and the second time it  will
   be 10 (5 * 2), so the result will be 20. Function arguments are filters, and filters expect an input when invoked.

   If you want the value-argument behaviour for defining simple functions, you can just use a variable:

       def addvalue(f): f as $f | map(. + $f);

   Or use the short-hand:

       def addvalue($f): ...;

   With  either  definition, addvalue(.foo) will add the current input's .foo field to each element of the array. Do note
   that calling addvalue(.[]) will cause the map(. + $f) part to be evaluated once per value in the value  of  .  at  the
   call site.

   Multiple  definitions  using  the same function name are allowed. Each re-definition replaces the previous one for the
   same number of function arguments, but only for references from functions (or main program) subsequent to the re-defi‐
   nition. See also the section below on scoping.

       jq 'def addvalue(f): . + [f]; map(addvalue(.[0]))'
          [[1,2],[10,20]]
       => [[1,2,1], [10,20,10]]

       jq 'def addvalue(f): f as $x | map(. + $x); addvalue(.[0])'
          [[1,2],[10,20]]
       => [[1,2,1,2], [10,20,1,2]]

Scoping
   There  are two types of symbols in jq: value bindings (a.k.a., "variables"), and functions. Both are scoped lexically,
   with expressions being able to refer only to symbols that have been defined "to the left" of them. The only  exception
   to this rule is that functions can refer to themselves so as to be able to create recursive functions.

   For  example,  in  the  following  expression  there  is a binding which is visible "to the right" of it, ... | .*3 as
   $times_three | [. + $times_three] | ..., but not  "to  the  left".  Consider  this  expression  now,  ...  |  (.*3  as
   $times_three | [.+ $times_three]) | ...: here the binding $times_three is not visible past the closing parenthesis.

Reduce
   The  reduce  syntax in jq allows you to combine all of the results of an expression by accumulating them into a single
   answer. As an example, we'll pass [3,2,1] to this expression:

       reduce .[] as $item (0; . + $item)

   For each result that .[] produces, . + $item is run to accumulate a running total, starting from 0. In  this  example,
   .[] produces the results 3, 2, and 1, so the effect is similar to running something like this:

       0 | (3 as $item | . + $item) |
           (2 as $item | . + $item) |
           (1 as $item | . + $item)

       jq 'reduce .[] as $item (0; . + $item)'
          [10,2,5,3]
       => 20

isempty(exp)
   Returns true if exp produces no outputs, false otherwise.

       jq 'isempty(empty)'
          null
       => true

limit(n; exp)
   The limit function extracts up to n outputs from exp.

       jq '[limit(3;.[])]'
          [0,1,2,3,4,5,6,7,8,9]
       => [0,1,2]

first(expr), last(expr), nth(n; expr)
   The first(expr) and last(expr) functions extract the first and last values from expr, respectively.

   The nth(n; expr) function extracts the nth value output by expr. This can be defined as def nth(n; expr): last(limit(n
   + 1; expr));. Note that nth(n; expr) doesn't support negative values of n.

       jq '[first(range(.)), last(range(.)), nth(./2; range(.))]'
          10
       => [0,9,5]

first, last, nth(n)
   The first and last functions extract the first and last values from any array at ..

   The nth(n) function extracts the nth value of any array at ..

       jq '[range(.)]|[first, last, nth(5)]'
          10
       => [0,9,5]

foreach
   The foreach syntax is similar to reduce, but intended to allow the construction of limit and reducers that produce in‐
   termediate results (see example).

   The form is foreach EXP as $var (INIT; UPDATE; EXTRACT). Like reduce, INIT is evaluated once to produce a state value,
   then each output of EXP is bound to $var, UPDATE is evaluated for each output of EXP with the current state  and  with
   $var  visible.  Each  value  output  by UPDATE replaces the previous state. Finally, EXTRACT is evaluated for each new
   state to extract an output of foreach.

   This is mostly useful only for constructing reduce- and limit-like functions. But it is much more general, as  it  al‐
   lows for partial reductions (see the example below).

       jq '[foreach .[] as $item ([[],[]]; if $item == null then [[],.[0]] else [(.[0] + [$item]),[]] end; if $item == null then .[1] else empty end)]'
          [1,2,3,4,null,"a","b",null]
       => [[1,2,3,4],["a","b"]]

Recursion
   As  described  above,  recurse  uses recursion, and any jq function can be recursive. The while builtin is also imple‐
   mented in terms of recursion.

   Tail calls are optimized whenever the expression to the left of the recursive call outputs its last value. In practice
   this  means that the expression to the left of the recursive call should not produce more than one output for each in‐
   put.

   For example:

       def recurse(f): def r: ., (f | select(. != null) | r); r;

       def while(cond; update):
         def _while:
           if cond then ., (update | _while) else empty end;
         _while;

       def repeat(exp):
         def _repeat:
           exp, _repeat;
         _repeat;

Generators and iterators
   Some jq operators and functions are actually generators in that they can produce zero, one, or more  values  for  each
   input,  just  as  one might expect in other programming languages that have generators. For example, .[] generates all
   the values in its input (which must be an array or an object), range(0; 10) generates the integers between 0  and  10,
   and so on.

   Even  the  comma  operator  is a generator, generating first the values generated by the expression to the left of the
   comma, then for each of those, the values generate by the expression on the right of the comma.

   The empty builtin is the generator that produces zero outputs. The empty builtin backtracks to the preceding generator
   expression.

   All  jq functions can be generators just by using builtin generators. It is also possible to define new generators us‐
   ing only recursion and the comma operator. If the recursive call(s) is(are) "in tail position" then the generator will
   be  efficient.  In the example below the recursive call by _range to itself is in tail position. The example shows off
   three advanced topics: tail recursion, generator construction, and sub-functions.

       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)); range(0; 10; 3)'
          null
       => 0, 3, 6, 9

       jq 'def while(cond; update): def _while: if cond then ., (update | _while) else empty end; _while; [while(.<100; .*2)]'
          1
       => [1,2,4,8,16,32,64]

FUNCTIONS

^

paths # outputs all paths
path(..) # same as paths but add the first empty array []

.foo, .foo.bar # take hierarchical arguments in structure
.foo? # Just like .foo, but does not output even an error when
.[] # returns all elements contained
.[]? # returns all elements contained, nothing & no error if not exists
.[<string>], .[2], .[-2:-1] # returns array contains selected indexes for array & string
| # pipe on output of each select
+ # Addition, takes two filters, applies them both to the same input, and adds the results together
- # Subtraction, operator can be used on arrays to remove occurrences of array´s elements
* / % # Multiplication, division, modulo
length # gets the length of various different types of value
keys, keys_unsorted # returns its keys in an array
has(key) # returns whether the input object has the given key, or the input array has an element at the given index
in # returns if the input string is the index of given object
path(path_expression) # 
del(path_expression) # the builtin function del removes a key and its corresponding value from an object
to_entries, from_entries, with_entries # these functions convert between an object and an array of key-value pairs
select(boolean_expression) # select(foo) produces its input unchanged if foo returns true for that input
arrays, objects, iterables, booleans, numbers, normals, finites, strings, nulls, values, scalars # these built-ins select only inputs that are arrays, objects, iterables (arrays or objects), booleans, numbers, normal numbers, finite numbers, strings, null, non-null values, and non-iterables, respectively
empty # returns no results. None at all. Not even null
map(x) # for any filter x, map(x) will run that filter for each element of the input array, and produce the outputs a new array
map_values(x) # similarly, map_values(x) will run that filter for each element, but it will return an object when an object is passed
add # takes as input an array, and produces as output the elements of the array added together
any, any(condition), any(generator; condition) # takes as input an array of boolean values, and produces true as output if any of the the elements of the array is true
all, all(condition), all(generator; condition) # takes as input an array of boolean values, and produces true as output if all of the the elements of the array are true
flatten, flatten(depth) # takes as input an array of nested arrays, and produces a flat array in which all arrays inside the original array have been recursively replaced by their values. You can pass an argument to it to specify how many levels of nesting to flatten
range(upto), range(from;upto) range(from;upto;by) # produces a range of numbers. range(4;10) produces 6 numbers, from 4 (inclusive) to 10 (exclusive). The numbers are produced as separate outputs. Use [range(4;10)] to get a range as an array
sort, sort_by(path_expression) # sorts its input, which must be an array
group_by(path_expression) # group_by(.foo) takes as input an array, groups the elements having the same .foo field into separate arrays, and produces all of these arrays as elements of a larger array, sorted by the value of the .foo field
min, max, min_by(path_exp), max_by(path_exp) # find the minimum or maximum element of the input array
unique, unique_by(path_exp) # takes as input an array and produces an array of the same elements, in sorted order, with duplicates removed
reverse # reverses an array
contains(element) # contains(b) will produce true if b is completely contained within the input. A string B is contained in a string A if B is a substring of A. An array B is contained in an array A if all elements in B are contained in any element in A. An object B is contained in object A if all of the values in B are contained in the value in A with the same key. All other types are assumed to be contained in each other if they are equal
indices(s) # outputs an array containing the indices in . where s occurs. The input may be an array, in which case if s is an array then the indices output will be those where all elements in . match those of s
index(s), rindex(s) # outputs the index of the first (index) or last (rindex) occurrence of s in the input
inside # inside(b) will produce true if the input is completely contained within b. It is, essentially, an inversed version of contains

startswith(str) # outputs true if . starts with the given string argument
ltrimstr(str) # outputs its input with the given prefix string removed, if it starts with it
rtrimstr(str) # outputs its input with the given suffix string removed, if it ends with it
explode # converts an input string into an array of the string´s codepoint numbers
implode # the inverse of explode
split # splits an input string on the separator argument
join(str) # joins the array of elements given as input, using the argument as separator. It is the inverse of split: that is, running split("foo") | join("foo") over any input string returns said input string
ascii_downcase, ascii_upcase # emit a copy of the input string with its alphabetic characters (a-z and A-Z) converted to the specified case

recurse(f), recurse, recurse(f; condition), recurse_down # allows you to search through a recursive structure, and extract interesting data from all levels
env # outputs an object representing jq´s environment
transpose # transpose a possibly jagged matrix (an array of arrays). Rows are padded with nulls so the result is always rectangular
bsearch(x) # bsearch(x) conducts a binary search for x in the input array. If the input is sorted and contains x, then bsearch(x) will return its index in the array; otherwise, if the array is sorted, it will return (-1 - ix) where ix is an insertion point such that the array would still be sorted after the insertion of x at ix. If the array is not sorted, bsearch(x) will return an integer that is probably of no interest
(foo) - string interpolation # inside a string, you can put an expression inside parens after a backslash. Whatever the expression returns will be interpolated into the string
Convert to/from JSON # tojson and fromjson builtins dump values as JSON texts or parse JSON texts into values, respectively. The tojson builtin differs from tostring in that tostring returns strings unmodified, while tojson encodes strings as JSON strings

DATE

^

builtins deal exclusively with time in UTC

fromdateiso8601 # parses datetimes in the ISO 8601 format to a number of seconds since the Unix epoch (1970-01-01T00:00:00Z). The todateiso8601 builtin does the inverse
fromdate # parses datetime strings. Currently fromdate only supports ISO 8601 datetime strings, but in the future it will attempt to parse datetime strings in more formats
todate # is an alias for todateiso8601
now # outputs the current time, in seconds since the Unix epoch
gmtime # consumes a number of seconds since the Unix epoch and outputs a "broken down time" representation of time as an array of numbers representing (in this order): the year, the month (zero-based), the day of the month, the hour of the day, the minute of the hour, the second of the minute, the day of the week, and the day of the year -- all one-based unless otherwise stated
mktime # consumes "broken down time" representations of time output by gmtime and strptime
strptime(fmt) # parses input strings matching the fmt argument. The output is in the "broken down time" representation consumed by gmtime and output by mktime
strftime(fmt) # formats a time with the given format

MATH

^

floor # returns the floor of its numeric input (integer part)
sqrt # returns the square root of its numeric input
tonumber # parses its input as a number. It will convert correctly-formatted strings to their numeric equivalent, leave numbers alone, and give an error on all other input
type # returns the type of its argument as a string, which is one of null, boolean, number, string, array or object

LOOP

^

while(cond; update) # allows you to repeatedly apply an update to . until cond is false
until(cond; next) # allows you to repeatedly apply the expression next, initially to . then to its own output, until cond is true

ASSIGNMENT

^

= # filter .foo = 1 will take as input an object and produce as output an object with the "foo" field set to 1
|= # jq provides the "update" operator ´|=´, which takes a filter on the right-hand side and works out the new value for the property of . being assigned to by running the old value through this expression
+=, -=, *=, /=, %=, //= # which are all equivalent to a |= . op b. So, += 1 can be used to increment values

CONDITIONALS-COMPARAISONS

^

==, != # produce ´true´ if the result of a and b are equal (that is, if they represent equivalent JSON documents) and ´false´ otherwise
=== # considering values equal only when they have the same type as well as the same value
>, >=, <=, < # return whether their left argument is greater than, greater than orequal to, less than or equal to or less than their right argument (respectively)
if then else # if A then B else C end will act the same as B if A produces a value other than false or null, but act the sameas C otherwise
and, or, not # They have the same standard of truth
// - alternative operator # a filter of the form a // b produces the same results as a, if a produces results other than false and null. Otherwise, a // b produces the same results as b
try-catch # errors can be caught by using try EXP catch EXP. The first expression is executed, and if it fails then the second is executed with the error message. The output of the handler, if any, is output as if it had been theoutput of the expression to try
? operator # used as EXP?, is shorthand for try EXP

REGEXP

^

test(val), test(regex; flags) # like match, but does not return match objects, only true or false for whether or not the regex matches the input
match(val), match(regex; flags) # match outputs an object for each match it finds
capture(val), capture(regex; flags) # collects the named captures in a JSON object, with the name of each capture as the key, and the matched string as the corresponding value
scan(regex), scan(regex; flags) # emit a stream of the non-overlapping substrings of the input that match the regex in accordance with the flags, if any have been specified
split(regex; flags) # for backwards compatibility, split splits on a string, not a regex
splits(regex), splits(regex; flags) # these provide the same results as their split counterparts, but as a stream instead of an array
sub(regex; tostring) sub(regex; string; flags) # emit the string obtained by replacing the first match of regex in the input string with tostring, after interpolation. tostring should be a jq string, and may contain references to named captures
gsub(regex; string), gsub(regex; string; flags) # gsub is like sub but all the non-overlapping occurrences of the regex are replaced by the string, after interpolation

Reduce # allows you to combine all of the results of an expression by accumulating them into a single answer
limit(n; exp) # extracts up to n outputs from exp

first(expr), last(expr) # The first(expr) and last(expr) functions extract the first and last values from expr, respectively
nth(n; expr) # extracts the nth value output by expr
first, last # extract the first and last values from any array at
nth(n) # extracts the nth value of any array at
foreach # is similar to reduce, but intended to allow the construction of limit and reducers that produce intermediate results