JQ(1)                                                                    JQ(1)

       jq - Command-line JSON processor

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

       jq  can transform JSON in various ways, by selecting, iterating, reduc-
       ing 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. White-
       space 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.

       The options are described in the #INVOKING-JQ section; they mostly con-
       cern  input and output formatting. The filter is written in the jq lan-
       guage and specifies how to transform the input file or document.

       A jq program is a "filter": it takes an input, and produces an  output.
       There are a lot of builtin filters for extracting a particular field of
       an object, or converting a number to a string, or various  other  stan-
       dard tasks.

       Filters  can  be  combined in various ways - you can pipe the output of
       one filter into another filter, or collect the output of a filter  into
       an array.

       Some  filters  produce  multiple results, for instance there's one that
       produces all the elements of its input array. Piping that filter into a
       second runs the second filter for each element of the array. Generally,
       things that would be done with loops and iteration in  other  languages
       are just done by gluing filters together in jq.

       It's  important  to remember that every filter has an input and an out-
       put. Even literals like "hello" or 42 are filters - they take an  input
       but  always produce the same literal as output. Operations that combine
       two filters, like addition, generally feed the same input to  both  and
       combine the results. So, you can implement an averaging filter as add /
       length - feeding the input array both to the add filter and the  length
       filter and then performing the division.

       But  that's  getting  ahead of ourselves. :) Let's start with something

       jq filters run on a stream of JSON data. The input to jq is parsed as a
       sequence  of  whitespace-separated JSON values which are passed through
       the provided filter one at a time. The  output(s)  of  the  filter  are
       written  to  standard  out, again as a sequence of whitespace-separated
       JSON data.

       Note: it is important to mind the shell's quoting rules. As  a  general
       rule  it's  best  to always quote (with single-quote characters) the jq
       program, as too many characters with special meaning  to  jq  are  also
       shell  meta-characters.  For  example,  jq "foo" will fail on most Unix
       shells because that will be the same as jq foo,  which  will  generally
       fail  because  foo is not defined. When using the Windows command shell
       (cmd.exe) it's best to use double quotes around your  jq  program  when
       given  on the command-line (instead of the -f program-file option), but
       then double-quotes in the jq program need backslash escaping.

       You can affect how jq reads and writes its input and output using  some
       command-line options:

       O   --version:

           Output the jq version and exit with zero.

       O   --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 mode also  parses  the
           output of jq without the --seq option.

       O   --stream:

           Parse  the input in streaming fashion, outputing arrays of path and
           leaf values (scalars and empty arrays or empty objects). For  exam-
           ple,  "a"  becomes  [[],"a"],  and [[],"a",["b"]] becomes [[0],[]],
           [[1],"a"], and [[1,0],"b"].

           This is useful for processing very large inputs. Use this  in  con-
           junction with filtering and the reduce and foreach syntax to reduce
           large inputs incrementally.

       O   --slurp/-s:

           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.

       O   --raw-input/-R:

           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 en-
           tire input is passed to the filter as a single long string.

       O   --null-input/-n:

           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 calcu-
           lator or to construct JSON data from scratch.

       O   --compact-output / -c:

           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.

       O   --tab:

           Use a tab for each indentation level instead of two spaces.

       O   --indent n:

           Use the given number of spaces (no more than 8) for indentation.

       O   --color-output / -C and --monochrome-output / -M:

           By default, jq outputs colored JSON if writing to a  terminal.  You
           can  force  it to produce color even if writing to a pipe or a file
           using -C, and disable color with -M.

           Colors can be configured with the  JQ_COLORS  environment  variable
           (see below).

       O   --ascii-output / -a:

           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 ev-
           ery non-ASCII character replaced with  the  equivalent  escape  se-

       O   --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

       O   --sort-keys / -S:

           Output the fields of each object with the keys in sorted order.

       O   --raw-output / -r:

           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 fil-
           ters talk to non-JSON-based systems.

       O   --join-output / -j:

           Like -r but jq won't print a newline after each output.

       O   -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.

       O   -Ldirectory / -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  mod-
           ules below.

       O   -e / --exit-status:

           Sets  the exit status of jq to 0 if the last output values was nei-
           ther 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.

           Another  way  to set the exit status is with the halt_error builtin

       O   --arg name value:

           This option passes a value to the jq program as a predefined  vari-
           able.  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".

           Named   arguments   are   also  available  to  the  jq  program  as

       O   --argjson name JSON-text:

           This option passes a JSON-encoded value to the jq program as a pre-
           defined  variable.  If you run jq with --argjson foo 123, then $foo
           is available in the program and has the value 123.

       O   --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 --slurpfile foo bar, then $foo is available in  the
           program  and has an array whose elements correspond to the texts in
           the file named bar.

       O   --rawfile variable-name filename:

           This option reads in the named file and binds its contents  to  the
           given  global  variable. If you run jq with --rawfile foo bar, then
           $foo is available in the program and has a  string  whose  contents
           are to the texs in the file named bar.

       O   --argfile variable-name filename:

           Do not use. Use --slurpfile instead.

           (This  option  is  like --slurpfile, but when the file has just one
           text, then that is used, else an array  of  texts  is  used  as  in

       O   --args:

           Remaining  arguments  are  positional  string  arguments. These are
           available to the jq program as $ARGS.positional[].

       O   --jsonargs:

           Remaining arguments are positional JSON text arguments.  These  are
           available to the jq program as $ARGS.positional[].

       O   --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  con-
           taining  the  program  to  compile, then a line containing an error
           message to compare to the actual.

           Be warned that this option can change backwards-incompatibly.

   Identity: .
       The absolute simplest filter is . . This is a filter that takes its in-
       put  and produces it unchanged as output. That is, this is the identity

       Since jq by default pretty-prints all output, this trivial program  can
       be a useful way of formatting JSON output from, say, curl.

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

   Object Identifier-Index: .foo, .foo.bar
       The  simplest useful filter is .foo. When given a JSON object (aka dic-
       tionary 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.

       This  syntax only works for simple, identifier-like keys, that is, keys
       that are all made of alphanumeric characters and underscore, and  which
       do not start with a digit.

       If  the  key  contains special characters, you need to surround it with
       double quotes like this: ."foo$", or else .["foo$"].

       For example .["foo::bar"] and .["foo.bar"] work  while  .foo::bar  does
       not, and .foo.bar means .["foo"].["bar"].

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

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

           jq '.["foo"]'
              {"foo": 42}
           => 42

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

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

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

           jq '.["foo"]?'
              {"foo": 42}
           => 42

           jq '[.foo?]'
           => []

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

   Array Index: .[2]
       When the index value is an integer, .[<value>] can index arrays. Arrays
       are zero-based, so .[2] returns the third element.

       Negative indices are allowed, with -1 referring to the last element, -2
       referring to the next to last element, and so on.

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

           jq '.[2]'
              [{"name":"JSON", "good":true}, {"name":"XML", "good":false}]
           => null

           jq '.[-2]'
           => 2

   Array/String Slice: .[10:15]
       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  (ex-
       clusive).  Either  index may be negative (in which case it counts back-
       wards from the end of the array), or omitted (in which case  it  refers
       to the start or end of the array).

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

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

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

           jq '.[-2:]'
           => ["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.

       You can also use this on an object, and it will return all  the  values
       of the object.

           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  con-
       catenated  in order: first, all of the outputs produced by the left ex-
       pression, and then all of the outputs produced by the  right.  For  in-
       stance,  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]'
           => "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.

       If the one on the left produces multiple results, the one on the  right
       will  be  run  for each of those results. So, the expression .[] | .foo
       retrieves the "foo" field of each element of the input array.

       Note that .a.b.c is the same as .a | .b | .c.

       Note too that . is the input value at the particular stage in a  "pipe-
       line",  specifically:  where the . expression appears. Thus .a | . | .b
       is the same as .a.b, as the . in the middle refers to whatever value .a

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

       Parenthesis work as a grouping operator just as in any typical program-
       ming language.

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

       jq supports the same set of datatypes as JSON - numbers, strings, bool-
       eans,  arrays, objects (which in JSON-speak are hashes with only string
       keys), and "null".

       Booleans, null, strings and numbers are written  the  same  way  as  in
       javascript.  Just  like everything else in jq, these simple values take
       an input and produce an output - 42 is a valid jq expression that takes
       an input, ignores it, and returns 42 instead.

   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])

       Once you understand the "," operator, you can look at jq's array syntax
       in  a  different  light: the expression [1,2,3] is not using a built-in
       syntax for comma-separated arrays, but is instead applying the [] oper-
       ator  (collect  results)  to the expression 1,2,3 (which produces three
       different results).

       If you have a filter X that produces four results, then the  expression
       [X] will produce a single result, an array of four elements.

           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 parenthe-
       sized, e.g., {("a"+"b"):59}.

       The value can be any expression (although you may need to  wrap  it  in
       parentheses  if  it's  a complicated one), which gets applied to the {}
       expression's input (remember, all filters have an input and an output).

           {foo: .bar}

       will produce the JSON object {"foo":  42}  if  given  the  JSON  object
       {"bar":42,  "baz":43} as its input. You can use this to select particu-
       lar fields of an object: if the input is an object  with  "user",  "ti-
       tle",  "id", and "content" fields and you just want "user" and "title",
       you can write

           {user: .user, title: .title}

       Because that is so common, there's a shortcut syntax for it: {user, ti-

       If  one  of the expressions produces multiple results, multiple dictio-
       naries will be produced. If the input's

           {"user":"stedolan","titles":["JQ Primer", "More JQ"]}

       then the expression

           {user, title: .titles[]}

       will produce two outputs:

           {"user":"stedolan", "title": "JQ Primer"}
           {"user":"stedolan", "title": "More JQ"}

       Putting parentheses around the key means it will be evaluated as an ex-
       pression. With the same input as above,

           {(.user): .titles}


           {"stedolan": ["JQ Primer", "More JQ"]}

           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" ..

       This is particularly useful in conjunction with path(EXP) (also see be-
       low) and the ? operator.

           jq '..|.a?'
           => 1

       Some jq operator (for instance, +) do different things depending on the
       type of their arguments (arrays, numbers, etc.). However, jq never does
       implicit type conversions. If you try to add  a  string  to  an  object
       you'll get an error message and no result.

   Addition: +
       The  operator + takes two filters, applies them both to the same input,
       and adds the results together. What "adding" means depends on the types

       O   Numbers are added by normal arithmetic.

       O   Arrays are added by being concatenated into a larger array.

       O   Strings are added by being joined into a larger string.

       O   Objects  are added by merging, that is, inserting all the key-value
           pairs from both objects into a single combined object. If both  ob-
           jects  contain a value for the same key, the object on the right of
           the + wins. (For recursive merge use the * operator.)

       null can be added to any value, and returns the other value unchanged.

           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}'
           => {"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 ele-
       ments from the first array.

           jq '4 - .a'
           => 1

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

   Multiplication, division, modulo: *, /, and %
       These infix operators behave as expected when given two numbers.  Divi-
       sion 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 sepa-

       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'
           => 6

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

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

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

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

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

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

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

       O   The length of null is zero.

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

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

           jq 'utf8bytelength'
           => 2

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

       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, regardless of locale settings.

       When  keys is given an array, it returns the valid indices for that ar-
       ray: 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'
           => [0,1,2]

       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]

       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 array. map(.+1) will in-
       crement 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)'
           => [2,3,4]

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

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

       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  expres-
       sions.  The expression path(..|select(type=="boolean")) outputs all the
       paths to boolean values in ., and only those paths.

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

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

       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"]

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

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

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

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

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

           jq 'delpaths([["a","b"]])'

           => {"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_entries,  useful  for  doing
       some  operation  to  all keys and values of an object. from_entries ac-
       cepts 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}

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

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

           jq 'map(select(. >= 2))'
           => [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

       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'
           => 1, 2

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

       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.

       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).

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

           jq 'try error("\($__loc__)") catch .'
           => "{\"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 . itself).

       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]'
           => [[0],[1],[1,0],[1,1],[1,1,"a"]]

           jq '[paths(scalars)]'
           => [[0],[1,1,"a"]]

       The filter add takes as input an array, and produces as output the ele-
       ments 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'
           => "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 pro-
       duces 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.

       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 in-
       crement of 1.

       The three argument form generates numbers from to upto with  an  incre-
       ment of by.

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

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

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

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

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

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

       The floor function returns the floor of its numeric input.

           jq 'floor'
           => 3

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

           jq 'sqrt'
           => 3

       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

       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]"

       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 infi-
       nite.  The  isnan builtin returns true if its input is a NaN. The infi-
       nite builtin returns a positive infinite value. The nan builtin returns
       a  NaN. The isnormal builtin returns true if its input is a normal num-

       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'
           => "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:

       O   null

       O   false

       O   true

       O   numbers

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

       O   arrays, in lexical order

       O   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  ap-
       plying any jq filter.

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

           jq 'sort'
           => [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(.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.

       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

           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  spec-
       ify  a particular field or property to examine, e.g. min_by(.foo) finds
       the object with the smallest foo field.

           jq 'min'
           => 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 duplicates 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'
           => [1,2,3,5]

           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"]

       This function reverses an array.

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

       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  sub-
       string 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.

           jq 'contains("bar")'
           => 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

       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)'
           => [1,3,5]

           jq 'indices([1,2])'
           => [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

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

           jq 'inside("foobar")'
           => 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

       Outputs true if . starts with the given string argument.

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

       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 ar-
       ray. If given an argument n, it outputs all combinations of  n  repeti-
       tions 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]

       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"]

       Outputs its input with the given suffix string removed, if it ends with

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

       Converts  an  input string into an array of the string's codepoint num-

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

       The inverse of explode.

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

       Splits an input string on the separator argument.

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

       Joins the array of elements given as input, using the argument as sepa-
       rator.  It  is  the  inverse  of split: that is, running 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 objects in the input are not

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

           jq 'join(" ")'
           => "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 up-
       date 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 mem-
       ory if update produces at most one output for each input. See  advanced
       topics below.

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

   until(cond; next)
       The  until(cond;  next) function allows you to repeatedly apply the ex-
       pression next, initially to . then to its own  output,  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]'
           => 24

   recurse(f), recurse, recurse(f; condition), recurse_down
       The recurse(f) function allows you to search through a recursive struc-
       ture, and extract interesting data from all levels. 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,  .children[].children[].name,  and
       so on. You can do this with:

           recurse(.children[]) | .name

       When   called  without  an  argument,  recurse  is  equivalent  to  re-

       recurse(f) is identical to recurse(f; . != null) and can be used  with-
       out 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 inte-
       gers, 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 re-
       moved in the next major release.

       The recursive calls in recurse will not consume additional memory when-
       ever 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]}, 0, [1], 1

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

       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  pro-
       cessing  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 considered 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'
           => "less"

           jq 'env.PAGER'
           => "less"

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

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

       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.

           jq 'bsearch(0)'
           => 0

           jq 'bsearch(0)'
           => -1

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

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

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










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

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

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


       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 &lt; y"

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

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

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

       jq   provides   some  basic  date  handling  functionality,  with  some
       high-level and low-level builtins. In all cases these builtins deal ex-
       clusively 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

       Low-level jq interfaces to the C-library time functions are  also  pro-
       vided:  strptime,  strftime,  strflocaltime, mktime, gmtime, and local-
       time. Refer to your host operating system's documentation for the  for-
       mat  strings  used by strptime and strftime. Note: these are not neces-
       sarily stable interfaces in jq, particularly as to  their  localization

       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 be-
       fore March 1st 1900, or after December 31 2099.

       The localtime builtin works like the gmtime builtin, but using the  lo-
       cal 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  argu-
       ment.  The  output is in the "broken down time" representation 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

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

           jq 'fromdate'
           => 1425599507

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

           jq 'strptime("%Y-%m-%dT%H:%M:%SZ")|mktime'
           => 1425599507

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

       INDEX(stream; index_expression):

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

       JOIN($idx; stream; idx_expr):

       JOIN($idx; idx_expr):


       IN(source; s):

       Returns a list of all builtin functions in the format name/arity. Since
       functions with the same name but different arities are considered sepa-
       rate  functions,  all/0,  all/1,  and all/2 would all be present in the

   ==, !=
       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  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 instead.

       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 argu-
       ment 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'
           => true

       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 spe-
       cial 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"'
           => true

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

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

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

   Alternative operator: //
       A filter of the form a // b produces the same results as a, if  a  pro-
       duces results other than false and null. Otherwise, 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 similar to how or is some-
       times used in Python (jq's or operator is reserved for strictly Boolean

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

           jq '.foo // 42'
           => 42

       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 expression to try.

       The try EXP form uses empty as the exception handler.

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

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

           jq 'try error("some exception") catch .'
           => "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 $label_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]

       jq  uses  the  Oniguruma  regular  expression library, as do php, ruby,
       TextMate, Sublime Text, etc, so the description here will focus  on  jq

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

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

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

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

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

       O   i - Case insensitive search

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

       O   n - Ignore empty matches

       O   p - Both s and m modes are enabled

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

       O   l - Find longest possible matches

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

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

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

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

       O   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")'
           => 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  fol-
       lowing fields:

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

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

       O   string - the string that it matched

       O   captures - an array of objects representing capturing groups.

       Capturing group objects have the following fields:

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

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

       O   string - the string that was captured

       O   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'

           => 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]+)")'
           => { "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 cap-
       tures  are,  in  effect,  presented 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.

       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

       It is also possible to define functions in jq, although this  is  is  a
       feature  whose  biggest  use is defining jq's standard 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 define 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 utilities 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  vari-
       ables aren't usually necessary in order to use a value twice.

       For  instance, calculating the average value of an array of numbers re-
       quires a few variables in most languages - at least one to hold the ar-
       ray,  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  pro-
       duces  its  sum,  and the length expression is given the array and pro-
       duces 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-aver-
       aging 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  author  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 pro-
       viding 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,  $sec-
       ond])  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,

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

       will work, but

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


       For programming language theorists, it's more accurate to say  that  jq
       variables  are  lexically-scoped bindings. In particular 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]'
           => [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}

   Destructuring Alternative Operator: ?//
       The destructuring alternative operator provides a concise mechanism for
       destructuring an input that can take one of several forms.

       Suppose we have an API that returns a list of resources and events  as-
       sociated with them, and we want to get the user_id and timestamp of the
       first event for each resource. The API (having been clumsily  converted
       from  XML)  will  only  wrap the events in an array if the resource has
       multiple events:

           {"resources": [{"id": 1, "kind": "widget", "events": {"action": "create", "user_id": 1, "ts": 13}},
                          {"id": 2, "kind": "widget", "events": [{"action": "create", "user_id": 1, "ts": 14}, {"action": "destroy", "user_id": 1, "ts": 15}]}]}

       We can use the destructuring alternative operator to handle this struc-
       tural change simply:

           .resources[] as {$id, $kind, events: {$user_id, $ts}} ?// {$id, $kind, events: [{$user_id, $ts}]} | {$user_id, $kind, $id, $ts}

       Or, if we aren't sure if the input is an array of values or an object:

           .[] as [$id, $kind, $user_id, $ts] ?// {$id, $kind, $user_id, $ts} | ...

       Each  alternative  need  not  define all of the same variables, but all
       named variables will be available to the subsequent  expression.  Vari-
       ables not matched in the alternative that succeeded will be null:

           .resources[] as {$id, $kind, events: {$user_id, $ts}} ?// {$id, $kind, events: [{$first_user_id, $first_ts}]} | {$user_id, $first_user_id, $kind, $id, $ts, $first_ts}

       Additionally, if the subsequent expression returns an error, the alter-
       native operator will attempt to try the next binding. Errors that occur
       during the final alternative are passed through.

           [[3]] | .[] as [$a] ?// [$b] | if $a != null then error("err: \($a)") else {$a,$b} end

           jq '.[] as {$a, $b, c: {$d, $e}} ?// {$a, $b, c: [{$d, $e}]} | {$a, $b, $d, $e}'
              [{"a": 1, "b": 2, "c": {"d": 3, "e": 4}}, {"a": 1, "b": 2, "c": [{"d": 3, "e": 4}]}]
           => {"a":1,"b":2,"d":3,"e":4}, {"a":1,"b":2,"d":3,"e":4}

           jq '.[] as {$a, $b, c: {$d}} ?// {$a, $b, c: [{$e}]} | {$a, $b, $d, $e}'
              [{"a": 1, "b": 2, "c": {"d": 3, "e": 4}}, {"a": 1, "b": 2, "c": [{"d": 3, "e": 4}]}]

           => {"a":1,"b":2,"d":3,"e":null}, {"a":1,"b":2,"d":null,"e":4}

           jq '.[] as [$a] ?// [$b] | if $a != null then error("err: \($a)") else {$a,$b} end'
           => {"a":null,"b":3}

   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 func-
       tion (in fact, this is how many of the builtins are defined).  A  func-
       tion 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 multiple times with differ-
       ent  inputs  (here f is run for each element of the input array). Argu-
       ments to a function work more like callbacks than like value arguments.
       This is important to understand. Consider:

           def foo(f): f|f;

       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 re-
       sult  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  ad-
       dvalue(.[])  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-definition. See also the section below on scoping.

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

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

       There  are  two  types of symbols in jq: value bindings (a.k.a., "vari-
       ables"), and functions. Both are scoped lexically, with expressions be-
       ing  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.

       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  re-
       sults  3,  2, and 1, so the effect is similar to running something like

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

           jq 'reduce .[] as $item (0; . + $item)'
           => 20

       Returns true if exp produces no outputs, false otherwise.

           jq 'isempty(empty)'
           => true

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

           jq '[limit(3;.[])]'
           => [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(.))]'
           => [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)]'
           => [0,9,5]

       The foreach syntax is similar to reduce, but intended to allow the con-
       struction  of limit and reducers that produce intermediate results (see

       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 allows for partial reduc-
       tions (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],["a","b"]]

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

       Tail calls are optimized whenever the expression to the left of the re-
       cursive  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 input.

       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;

           def repeat(exp):
             def _repeat:
               exp, _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 exam-
       ple, .[] 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 using 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  recur-
       sive  call  by  _range to itself is in tail position. The example shows
       off three advanced topics: tail recursion, generator construction,  and

           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)'
           => 0, 3, 6, 9

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

       jq  currently only has IEEE754 double-precision (64-bit) floating point
       number support.

       Besides simple arithmetic operators such as +, jq also has  most  stan-
       dard math functions from the C math library. C math functions that take
       a single input argument (e.g., sin()) are available as zero-argument jq
       functions. C math functions that take two input arguments (e.g., pow())
       are available as two-argument jq functions that ignore .. C math  func-
       tions  that  take three input arguments are available as three-argument
       jq functions that ignore ..

       Availability of standard math functions depends on the availability  of
       the  corresponding  math  functions in your operating system and C math
       library. Unavailable math functions will be defined but will  raise  an

       One-input  C math functions: acos acosh asin asinh atan atanh cbrt ceil
       cos cosh erf erfc exp exp10 exp2 expm1 fabs floor gamma  j0  j1  lgamma
       log  log10  log1p  log2 logb nearbyint pow10 rint round significand sin
       sinh sqrt tan tanh tgamma trunc y0 y1.

       Two-input C math functions: atan2 copysign drem fdim fmax fmin fmod fr-
       exp  hypot jn ldexp modf nextafter nexttoward pow remainder scalb scal-
       bln yn.

       Three-input C math functions: fma.

       See your system's manual for more information on each of these.

       At this time jq has minimal support for I/O, mostly in the form of con-
       trol over when inputs are read. Two builtins functions are provided for
       this, input and inputs, that read from the same sources  (e.g.,  stdin,
       files  named on the command-line) as jq itself. These two builtins, and
       jq's own reading actions, can be interleaved with each other.

       Two builtins provide minimal output capabilities,  debug,  and  stderr.
       (Recall  that  a  jq  program's output values are always output as JSON
       texts on stdout.) The debug builtin can have  application-specific  be-
       havior, such as for executables that use the libjq C API but aren't the
       jq executable itself. The stderr builtin outputs its input in raw  mode
       to stder with no additional decoration, not even a newline.

       Most  jq builtins are referentially transparent, and yield constant and
       repeatable value streams when applied to constant inputs. This  is  not
       true of I/O builtins.

       Outputs one new input.

       Outputs all remaining inputs, one by one.

       This is primarily useful for reductions over a program's inputs.

       Causes  a debug message based on the input value to be produced. The jq
       executable wraps the input value  with  ["DEBUG:",  <input-value>]  and
       prints  that and a newline on stderr, compactly. This may change in the

       Prints its input in raw and compact mode to stderr with  no  additional
       decoration, not even a newline.

       Returns  the  name of the file whose input is currently being filtered.
       Note that this will not work well unless jq is running in a  UTF-8  lo-

       Returns the line number of the input currently being filtered.

       With  the --stream option jq can parse input texts in a streaming fash-
       ion, allowing jq programs to start processing large JSON texts  immedi-
       ately  rather than after the parse completes. If you have a single JSON
       text that is 1GB in size, streaming it will allow  you  to  process  it
       much more quickly.

       However,  streaming isn't easy to deal with as the jq program will have
       [<path>, <leaf-value>] (and a few other forms) as inputs.

       Several builtins are provided to make handling streams easier.

       The  examples  below  use  the  streamed  form  of  [0,[1]],  which  is

       Streaming  forms include [<path>, <leaf-value>] (to indicate any scalar
       value, empty array, or empty object), and [<path>] (to indicate the end
       of  an  array  or  object). Future versions of jq run with --stream and
       -seq may output additional forms such as ["error message"] when an  in-
       put text fails to parse.

       Consumes  a  number  as input and truncates the corresponding number of
       path elements from the left of the outputs of the given  streaming  ex-

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

       Outputs values corresponding to the stream expression's outputs.

           jq 'fromstream(1|truncate_stream([[0],1],[[1,0],2],[[1,0]],[[1]]))'
           => [2]

       The tostream builtin outputs the streamed form of its input.

           jq '. as $dot|fromstream($dot|tostream)|.==$dot'
           => true

       Assignment  works  a  little differently in jq than in most programming
       languages. jq doesn't distinguish between references to and  copies  of
       something  - two objects or arrays are either equal or not equal, with-
       out any further notion of being "the same object" or "not the same  ob-

       If  an  object  has two fields which are arrays, .foo and .bar, and you
       append something to .foo, then .bar will not get bigger, even if you've
       previously  set .bar = .foo. If you're used to programming in languages
       like Python, Java, Ruby, Javascript, etc. then you can think of  it  as
       though  jq does a full deep copy of every object before it does the as-
       signment (for performance it doesn't actually do that, but  that's  the
       general idea).

       This means that it's impossible to build circular values in jq (such as
       an array whose first element is itself). This is quite intentional, and
       ensures  that  anything  a jq program can produce can be represented in

       All the assignment  operators  in  jq  have  path  expressions  on  the
       left-hand  side (LHS). The right-hand side (RHS) provides values to set
       to the paths named by the LHS path expressions.

       Values in jq are always immutable. Internally, assignment works by  us-
       ing  a reduction to compute new, replacement values for . that have had
       all the desired assignments applied to ., then outputting the  modified
       value.  This  might  be  made  clear  by  this example: {a:{b:{c:1}}} |
       (.a.b|=3), .. This will output  {"a":{"b":3}}  and  {"a":{"b":{"c":1}}}
       because  the  last  sub-expression, ., sees the original value, not the
       modified value.

       Most users will want to use modification assignment operators, such  as
       |= or +=, rather than =.

       Note  that the LHS of assignment operators refers to a value in .. Thus
       $var.foo = 1 won't work as expected ($var.foo is not a valid or  useful
       path expression in .); use $var | .foo = 1 instead.

       Note too that .a,.b=0 does not set .a and .b, but (.a,.b)=0 sets both.

   Update-assignment: |=
       This is the "update" operator '|='. It 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. For instance,
       (.foo, .bar) |= .+1 will build an object with the "foo"  field  set  to
       the  input's "foo" plus 1, and the "bar" field set to the input's "bar"
       plus 1.

       The left-hand side can be any general path expression; see path().

       Note that the left-hand side of '|=' refers  to  a  value  in  ..  Thus
       $var.foo  |=  .  + 1 won't work as expected ($var.foo is not a valid or
       useful path expression in .); use $var | .foo |= . + 1 instead.

       If the right-hand side  outputs  no  values  (i.e.,  empty),  then  the
       left-hand side path will be deleted, as with del(path).

       If the right-hand side outputs multiple values, only the first one will
       be used (COMPATIBILITY NOTE: in jq 1.5 and earlier releases, it used to
       be that only the last one was used).

           jq '(..|select(type=="boolean")) |= if . then 1 else 0 end'
           => [1,0,[5,1,[1,[0]],0]]

   Arithmetic update-assignment: +=, -=, *=, /=, %=, //=
       jq has a few operators of the form a op= b, which are all equivalent to
       a |= . op b. So, += 1 can be used to increment values, being  the  same
       as |= . + 1.

           jq '.foo += 1'
              {"foo": 42}
           => {"foo": 43}

   Plain assignment: =
       This  is the plain assignment operator. Unlike the others, the input to
       the  right-hand-side  (RHS)  is  the  same  as   the   input   to   the
       left-hand-side  (LHS)  rather  than  the value at the LHS path, and all
       values output by the RHS will be used (as shown below).

       If the RHS of '=' produces multiple values, then for each such value jq
       will  set the paths on the left-hand side to the value and then it will
       output  the  modified  ..   For   example,   (.a,.b)=range(2)   outputs
       {"a":0,"b":0},  then  {"a":1,"b":1}. The "update" assignment forms (see
       above) do not do this.

       This example should show the difference between '=' and '|=':

       Provide input '{"a": {"b": 10}, "b": 20}' to the programs:

       .a = .b

       .a |= .b

       The former will set the "a" field of the input to the "b" field of  the
       input,  and  produce the output {"a": 20, "b": 20}. The latter will set
       the "a" field of the input to the  "a"  field's  "b"  field,  producing
       {"a": 10, "b": 20}.

       Another example of the difference between '=' and '|=':


       outputs '{"a":0,"b":0}', '{"a":1,"b":1}', and '{"a":2,"b":2}', while


       outputs just '{"a":0,"b":0}'.

   Complex assignments
       Lots  more  things are allowed on the left-hand side of a jq assignment
       than in most languages. We've already seen simple field accesses on the
       left  hand  side, and it's no surprise that array accesses work just as

           .posts[0].title = "JQ Manual"

       What may come as a surprise is that the expression on the left may pro-
       duce multiple results, referring to different points in the input docu-

           .posts[].comments |= . + ["this is great"]

       That example appends the string "this is great" to the "comments" array
       of  each  post  in the input (where the input is an object with a field
       "posts" which is an array of posts).

       When jq encounters an assignment like 'a = b', it  records  the  "path"
       taken  to  select  a part of the input document while executing a. This
       path is then used to find which part of the input to change while  exe-
       cuting  the assignment. Any filter may be used on the left-hand side of
       an equals - whichever paths it selects from the input will be where the
       assignment is performed.

       This  is  a very powerful operation. Suppose we wanted to add a comment
       to blog posts, using the same "blog" input above. This  time,  we  only
       want  to  comment on the posts written by "stedolan". We can find those
       posts using the "select" function described earlier:

           .posts[] | select(.author == "stedolan")

       The paths provided by this operation point to each of  the  posts  that
       "stedolan"  wrote,  and  we can comment on each of them in the same way
       that we did before:

           (.posts[] | select(.author == "stedolan") | .comments) |=
               . + ["terrible."]

       jq has a library/module system. Modules are files whose  names  end  in

       Modules imported by a program are searched for in a default search path
       (see below). The import and include directives allow  the  importer  to
       alter this path.

       Paths in the a search path are subject to various substitutions.

       For  paths starting with "~/", the user's home directory is substituted
       for "~".

       For paths starting with "$ORIGIN/", the path of the  jq  executable  is
       substituted for "$ORIGIN".

       For paths starting with "./" or paths that are ".", the path of the in-
       cluding file is substituted for ".". For top-level  programs  given  on
       the command-line, the current directory is used.

       Import directives can optionally specify a search path to which the de-
       fault is appended.

       The default search path is the search path given to the -L command-line
       option, else ["~/.jq", "$ORIGIN/../lib/jq", "$ORIGIN/../lib"].

       Null and empty string path elements terminate search path processing.

       A  dependency  with  relative  path  "foo/bar" would be searched for in
       "foo/bar.jq" and "foo/bar/bar.jq" in the given search path. This is in-
       tended to allow modules to be placed in a directory along with, for ex-
       ample, version control files, README files, and so on, but also to  al-
       low for single-file modules.

       Consecutive  components with the same name are not allowed to avoid am-
       biguities (e.g., "foo/foo").

       For  example,  with  -L$HOME/.jq  a  module  foo  can   be   found   in
       $HOME/.jq/foo.jq and $HOME/.jq/foo/foo.jq.

       If "$HOME/.jq" is a file, it is sourced into the main program.

   import RelativePathString as NAME [<metadata>];
       Imports  a  module found at the given path relative to a directory in a
       search path. A ".jq" suffix will be added to the relative path  string.
       The module's symbols are prefixed with "NAME::".

       The optional metadata must be a constant jq expression. It should be an
       object with keys like "homepage" and so on. At this time jq  only  uses
       the  "search"  key/value  of  the  metadata.  The metadata is also made
       available to users via the modulemeta builtin.

       The "search" key in the metadata, if present, should have a  string  or
       array  value (array of strings); this is the search path to be prefixed
       to the top-level search path.

   include RelativePathString [<metadata>];
       Imports a module found at the given path relative to a directory  in  a
       search  path  as  if  it were included in place. A ".jq" suffix will be
       added to the relative path string. The module's  symbols  are  imported
       into  the  caller's  namespace  as if the module's content had been in-
       cluded directly.

       The optional metadata must be a constant jq expression. It should be an
       object  with  keys like "homepage" and so on. At this time jq only uses
       the "search" key/value of the  metadata.  The  metadata  is  also  made
       available to users via the modulemeta builtin.

   import RelativePathString as $NAME [<metadata>];
       Imports  a JSON file found at the given path relative to a directory in
       a search path. A ".json" suffix will be  added  to  the  relative  path
       string. The file's data will be available as $NAME::NAME.

       The optional metadata must be a constant jq expression. It should be an
       object with keys like "homepage" and so on. At this time jq  only  uses
       the  "search"  key/value  of  the  metadata.  The metadata is also made
       available to users via the modulemeta builtin.

       The "search" key in the metadata, if present, should have a  string  or
       array  value (array of strings); this is the search path to be prefixed
       to the top-level search path.

   module <metadata>;
       This directive is entirely optional. It's not required for proper oper-
       ation.  It  serves  only  the purpose of providing metadata that can be
       read with the modulemeta builtin.

       The metadata must be a constant jq expression. It should be  an  object
       with  keys  like "homepage". At this time jq doesn't use this metadata,
       but it is made available to users via the modulemeta builtin.

       Takes a module name as input and outputs the module's  metadata  as  an
       object,  with  the  module's  imports  (including metadata) as an array
       value for the "deps" key.

       Programs can use this to query a module's metadata,  which  they  could
       then use to, for example, search for, download, and install missing de-

       To configure alternative colors  just  set  the  JQ_COLORS  environment
       variable  to  colon-delimited list of partial terminal escape sequences
       like "1;31", in this order:

       O   color for null

       O   color for false

       O   color for true

       O   color for numbers

       O   color for strings

       O   color for arrays

       O   color for objects

       The  default  color  scheme   is   the   same   as   setting   "JQ_COL-

       This  is  not  a  manual for VT100/ANSI escapes. However, each of these
       color specifications should consist  of  two  numbers  separated  by  a
       semi-colon, where the first number is one of these:

       O   1 (bright)

       O   2 (dim)

       O   4 (underscore)

       O   5 (blink)

       O   7 (reverse)

       O   8 (hidden)

       and the second is one of these:

       O   30 (black)

       O   31 (red)

       O   32 (green)

       O   33 (yellow)

       O   34 (blue)

       O   35 (magenta)

       O   36 (cyan)

       O   37 (white)

       Presumably. Report them or discuss them at:


       Stephen Dolan <mu@netsoc.tcd.ie>

                                 January 2021                            JQ(1)
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