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Updated: Thursday, June 13, 2019
 
 

jq (1)

Name

jq - line JSON processor

Synopsis

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.

Description

JQ(1)                                                                    JQ(1)



NAME
       jq - Command-line JSON processor

SYNOPSIS
       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.

FILTERS
       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
       simpler:

INVOKING JQ
       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
           entire 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
           every non-ASCII  character  replaced  with  the  equivalent  escape
           sequence.

       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
           elsewhere).

       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
           function.

       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
           $ARGS.named.

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

       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
           --slurpfile.)

       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.



BASIC FILTERS
   Identity: .
       The  absolute  simplest  filter  is . . This is a filter that takes its
       input and produces it unchanged as output. That is, this is  the  iden-
       tity operator.

       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
       array 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?]'
              [1,2]
           => []



   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]'
              [1,2,3]
           => 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
       (exclusive). Either index may be negative  (in  which  case  it  counts
       backwards  from  the  end  of  the array), or omitted (in which case it
       refers to the start or end of the array).



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

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

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

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



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

       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
       expression,  and  then  all  of  the outputs produced by the right. For
       instance, filter .foo, .bar, produces both the "foo" fields  and  "bar"
       fields as separate outputs.



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

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

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



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

       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
       produced.



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



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



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



TYPES AND VALUES
       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",
       "title", "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,
       title}.

       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
       expression. With the same input as above,



           {(.user): .titles}



       produces



           {"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
       below) and the ? operator.



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



BUILTIN OPERATORS AND FUNCTIONS
       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
       involved:

       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
           objects 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}'
              null
           => {"a": 42, "b": 2, "c": 3}



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



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

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



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

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



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

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

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

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



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

       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



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



           jq 'utf8bytelength'
              "\u03bc"
           => 2



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

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

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

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



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

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



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

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



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

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



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



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

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



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

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

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



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

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



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

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

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

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

       Note  that  the  path expressions are not different from normal 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)'
              null
           => ["a",0,"b"]

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



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



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

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



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



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

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



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



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

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

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



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



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



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

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



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

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

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



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

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



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

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



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



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



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

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



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

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



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

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

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

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

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

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



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



   paths, paths(node_filter), leaf_paths
       paths outputs the paths to all the elements in  its  input  (except  it
       does not output the empty list, representing . 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]'
              [1,[[],{"a":2}]]
           => [[0],[1],[1,0],[1,1],[1,1,"a"]]

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



   add
       The filter add takes as input an array, and produces as output the 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'
              ["a","b","c"]
           => "abc"

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

           jq 'add'
              []
           => null



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

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

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

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



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

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

           jq 'any'
              []
           => false



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

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

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

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



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

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

           jq 'all'
              []
           => true



   flatten, flatten(depth)
       The filter flatten takes as input an array of nested arrays,  and  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
       increment of 1.

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



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

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

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

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

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

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



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



           jq 'floor'
              3.14159
           => 3



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



           jq 'sqrt'
              9
           => 3



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



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



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



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



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



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



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

       Note that division by zero raises an error.

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



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

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



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

       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
       applying any jq filter.

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



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

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



   group_by(path_expression)
       group_by(.foo)  takes as input an array, groups the elements having the
       same .foo field into separate arrays, and 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
       above.



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



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

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



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

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



   unique, unique_by(path_exp)
       The  unique  function  takes as input an array and produces an array of
       the same elements, in sorted order, with 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'
              [1,2,5,3,5,3,1,3]
           => [1,2,3,5]

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

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



   reverse
       This function reverses an array.



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



   contains(element)
       The filter contains(b) will produce true if b is  completely  contained
       within  the input. A string B is contained in a string A if B is a 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")'
              "foobar"
           => true

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

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

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

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



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



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

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

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



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



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

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



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



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

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

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

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

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



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



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



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



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



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



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



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



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



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



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



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



   implode
       The inverse of explode.



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



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



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



   join(str)
       Joins the array of elements given as input, using the argument as 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
       supported.



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

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



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

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

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



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



   until(cond; next)
       The until(cond; next) function  allows  you  to  repeatedly  apply  the
       expression  next,  initially to . then to its own 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]'
              4
           => 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
       recurse(.[]?).

       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
       removed 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]}
           => {"a":0,"b":[1]}, 0, [1], 1

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



   walk(f)
       The walk(f) function applies f recursively to every  component  of  the
       input  entity.  When an array is encountered, f is first applied to its
       elements and then to the array itself; when an object is encountered, f
       is first applied to all the values and then to the object. In practice,
       f will usually test the type of its input, as illustrated in  the  fol-
       lowing  examples.  The  first example highlights the usefulness of 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'
              null
           => "less"

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



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



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



   bsearch(x)
       bsearch(x) conducts a binary search for x in the input  array.  If  the
       input  is  sorted and contains x, then bsearch(x) will return its index
       in the array; otherwise, if the array is sorted, it will return  (-1  -
       ix)  where  ix is an 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)'
              [0,1]
           => 0

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

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



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



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



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



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

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

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



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

       @text:

              Calls tostring, see that function for details.

       @json:

              Serializes the input as JSON.

       @html:

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

       @uri:

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

       @csv:

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

       @tsv:

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

       @sh:

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

       @base64:

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

       @base64d:

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

       This  syntax can be combined with string interpolation in a useful way.
       You can follow a @foo token with a string 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
       jq?"}:



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



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



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

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

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

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



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

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

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

       The todate builtin is an alias for todateiso8601.

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

       Low-level  jq  interfaces to the C-library time functions are also 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
       functionality.

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

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

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

       The  strptime(fmt)  builtin parses input strings matching the fmt 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
       "%Y-%m-%dT%H:%M:%SZ".

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

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

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



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

       INDEX(stream; index_expression):

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

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

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

       JOIN($idx; stream; idx_expr):

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

       JOIN($idx; idx_expr):

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

       IN(s):

              This builtin outputs true if . appears in the given stream, oth-
              erwise it outputs false.

       IN(source; s):

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

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

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

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



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



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

       Checking  for false or null is a simpler notion of "truthiness" than is
       found in Javascript or Python, but it means that you'll sometimes  have
       to  be  more  explicit  about  the  condition  you want: you can't test
       whether, e.g. a string is empty using if  .name  then  A  else  B  end,
       you'll  need  something more like if (.name | length) > 0 then A else B
       end 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'
              2
           => true



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

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

       not  is  in  fact  a builtin function rather than an operator, so it is
       called as a filter to which things can be piped rather than  with  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"'
              null
           => true

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

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

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



   Alternative operator: //
       A  filter  of the form a // b produces the same results as a, if a 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
       operations).



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

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



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

       The try EXP form uses empty as the exception handler.



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

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

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



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

       For example:



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



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



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



       The break $label_name expression will cause the program to  to  act  as
       though the nearest (to the left) label $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]



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

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



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



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

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

       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")'
              "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'
              "abc"
           => 3



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



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



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

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

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

   sub(regex; tostring) sub(regex; string; flags)
       Emit  the  string obtained by replacing the first match of regex in the
       input string with tostring, after interpolation. tostring should  be  a
       jq string, and may contain references to named captures. The named 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.

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

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

       It  is  also  possible to define functions in jq, although this is is a
       feature whose biggest use is defining jq's 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
       requires  a  few variables in most languages - at least one to hold the
       array, perhaps one for each element or for a loop counter. In jq,  it's
       simply  add  /  length - the add expression is given the array and 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,
       so



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



       will work, but



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



       won't.

       For  programming  language theorists, it's more accurate to say that jq
       variables are lexically-scoped bindings. In 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]'
              5
           => [10,5]

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

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



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



           def increment: . + 1;



       From then on, increment is usable as a filter just like a builtin 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;
           5|foo(.*2)



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

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



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



       Or use the short-hand:



           def addvalue($f): ...;



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

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



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

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



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

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

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



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



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



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

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



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



           jq 'isempty(empty)'
              null
           => true



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



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



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

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



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



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

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



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



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

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

       This is mostly useful only  for  constructing  reduce-  and  limit-like
       functions. But it is much more general, as it 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,null,"a","b",null]
           => [[1,2,3,4],["a","b"]]



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

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

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



   Generators and iterators
       Some jq operators and functions are actually generators  in  that  they
       can produce zero, one, or more values for each input, just as one might
       expect in other programming languages that have generators.  For  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
       sub-functions.



           jq 'def range(init; upto; by): def _range: if (by > 0 and . < upto) or (by < 0 and . > upto) then ., ((.+by)|_range) else . end; if by == 0 then init else init|_range end | select((by > 0 and . < upto) or (by < 0 and . > upto)); range(0; 10; 3)'
              null
           => 0, 3, 6, 9

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



MATH
       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
       error.

       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
       frexp hypot jn ldexp modf  nextafter  nexttoward  pow  remainder  scalb
       scalbln yn.

       Three-input C math functions: fma.

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

I/O
       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
       behavior, 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.

   input
       Outputs one new input.

   inputs
       Outputs all remaining inputs, one by one.

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

   debug
       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
       future.

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

   input_filename
       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
       locale.

   input_line_number
       Returns the line number of the input currently being filtered.

STREAMING
       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
       [[0],0],[[1,0],1],[[1,0]],[[1]].

       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
       input text fails to parse.

   truncate_stream(stream_expression)
       Consumes a number as input and truncates the  corresponding  number  of
       path  elements  from  the  left  of  the outputs of the given streaming
       expression.



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



   fromstream(stream_expression)
       Outputs values corresponding to the stream expression's outputs.



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



   tostream
       The tostream builtin outputs the streamed form of its input.



           jq '. as $dot|fromstream($dot|tostream)|.==$dot'
              [0,[1,{"a":1},{"b":2}]]
           => true



ASSIGNMENT
       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
       object".

       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
       assignment (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
       JSON.

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

       Values  in  jq  are  always  immutable. Internally, assignment works by
       using a reduction to compute new, replacement values for  .  that  have
       had all the desired assignments applied to ., then outputting the modi-
       fied 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'
              [true,false,[5,true,[true,[false]],false]]
           => [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 '|=':

       null|(.a,.b)=range(3)

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

       null|(.a,.b)|=range(3)

       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
       well:



           .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-
       ment:



           .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."]



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

       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
       including  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
       default 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
       intended to allow modules to be placed in a directory along  with,  for
       example,  version  control  files, README files, and so on, but also to
       allow for single-file modules.

       Consecutive components with the same name  are  not  allowed  to  avoid
       ambiguities (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
       included 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.

   modulemeta
       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
       dependencies.

COLORS
       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-
       ORS=1;30:0;39:0;39:0;39:0;32:1;39:1;39".

       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)



BUGS
       Presumably. Report them or discuss them at:



           https://github.com/stedolan/jq/issues



AUTHOR
       Stephen Dolan <mu@netsoc.tcd.ie>



ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | text/jq          |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+
NOTES
       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source   was   downloaded   from     https://github.com/stedolan/jq/ar-
       chive/jq-1.6rc1.tar.gz

       Further information about this software can be found on the open source
       community website at https://github.com/stedolan/jq.



                                 December 2017                           JQ(1)