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NAME

       jq - Command-line JSON processor

SYNOPSIS

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

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

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

       The options are described in  the  INVOKING  JQ  section;  they  mostly
       concern  input  and  output formatting. The filter is written in the jq
       language 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
       standard 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
       output. 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:

       ·   --version:

           Output the jq version and exit with zero.

       ·   --seq:

           Use  the  application/json-seq MIME type scheme for separating JSON
           texts in jq´s input and output. This means that an ASCII RS (record
           separator)  character is printed before each value on output and an
           ASCII LF (line feed) is printed  after  every  output.  Input  JSON
           texts that fail to parse are ignored (but warned about), discarding
           all subsequent input until the next RS. This more also  parses  the
           output of jq without the --seq option.

       ·   --stream:

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

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

       ·   --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.

       ·   --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.

       ·   --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
           calculator or to construct JSON data from scratch.

       ·   --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.

       ·   --tab:

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

       ·   --indent n:

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

       ·   --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.

       ·   --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.

       ·   --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).

       ·   --sort-keys / -S:

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

       ·   --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
           filters talk to non-JSON-based systems.

       ·   --join-output / -j:

           Like -r but jq won´t print a newline after each output.

       ·   -f filename / --from-file filename:

           Read  filter  from  the  file rather than from a command line, like
           awk´s -f option. You can also use ´#´ to make comments.

       ·   -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
           modules below.

       ·   -e / --exit-status:

           Sets the exit status of jq to 0  if  the  last  output  values  was
           neither false nor null, 1 if the last output value was either false
           or null, or 4 if no valid result was  ever  produced.  Normally  jq
           exits  with  2 if there was any usage problem or system error, 3 if
           there was a jq program compile error, or 0 if the jq program ran.

       ·   --arg name value:

           This option passes a value  to  the  jq  program  as  a  predefined
           variable.  If you run jq with --arg foo bar, then $foo is available
           in the program and has the value "bar". Note  that  value  will  be
           treated as a string, so --arg foo 123 will bind $foo to "123".

       ·   --argjson name JSON-text:

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

       ·   --slurpfile variable-name filename:

           This option reads all the JSON texts in the named file and binds an
           array of the parsed JSON values to the given  global  variable.  If
           you  run  jq  with --argfile foo bar, then $foo is available in the
           program and has an array whose elements correspond to the texts  in
           the file named bar.

       ·   --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.)

       ·   --run-tests [filename]:

           Runs  the  tests  in the given file or standard input. This must be
           the last option given and does not honor all preceding options. The
           input  consists  of  comment  lines, empty lines, and program lines
           followed by one input line, as many lines of output as are expected
           (one per output), and a terminating empty line. Compilation failure
           tests start with a line  containing  only  "%%FAIL",  then  a  line
           containing  the program to compile, then a line containing an error
           message to compare to the actual.

           Be warned that this option can change backwards-incompatibly.

BASIC FILTERS

   .
       The absolute simplest (and least interesting) filter is ..  This  is  a
       filter that takes its input and produces it unchanged as output.

       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!"

   .foo, .foo.bar
       The simplest useful filter is .foo.  When  given  a  JSON  object  (aka
       dictionary  or  hash) as input, it produces the value at the key "foo",
       or null if there´s none present.

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

       A filter of the form .foo.bar is equivalent to .foo|.bar.

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

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

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

   .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]
           => []

   .[<string>], .[2], .[10:15]
       You can also look up fields of an object  using  syntax  like  .["foo"]
       (.foo  above is a shorthand version of this). This one works for arrays
       as well, if  the  key  is  an  integer.  Arrays  are  zero-based  (like
       javascript), so .[2] returns the third element of the array.

       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).

       The .[2] syntax can be used to return the element at the  given  index.
       Negative indices are allowed, with -1 referring to the last element, -2
       referring to the next to last element, and so on.

       The .foo syntax only works for simply  keys  i.e.  keys  that  are  all
       alphanumeric  characters.  .[<string>]  works  with  keys  that contain
       special characters such as colons and dots. For  example  .["foo::bar"]
       and .["foo.bar"] work while .foo::bar and .foo.bar would not.

       The  ?  "operator"  can  also  be  used  with the slice operator, as in
       .[10:15]?, which outputs values where the inputs are slice-able.

           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 ´.[2:4]´
              ["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"]

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

   .[]
       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.

   ,
       If two filters are separated by a comma, then the  input  will  be  fed
       into both and there will be multiple outputs: 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"

   |
       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.

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

TYPES AND VALUES

       jq supports the same set of  datatypes  as  JSON  -  numbers,  strings,
       booleans,  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. 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  []
       operator  (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"]

   Objects - {}
       Like JSON, {} is for constructing objects (aka dictionaries or hashes),
       as in: {"a": 42, "b": 17}.

       If the keys are "sensible" (all alphabetic characters), then the quotes
       can be left off. 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}.  You can use this to select particular 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´s so common, there´s a shortcut syntax: {user, title}.

       If   one   of  the  expressions  produces  multiple  results,  multiple
       dictionaries 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"]}

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:

       ·   Numbers are added by normal arithmetic.

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

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

       ·   Objects are added by merging, that is, inserting all the  key-value
           pairs  from  both  objects  into  a single combined object. If both
           objects contain a value for the same key, the object on  the  right
           of the + wins. (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
       elements from the first array.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

       ·   The length of null is zero.

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

   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 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]

   path(path_expression)
       Outputs array representations of the given path expression  in  ..  The
       outputs  are  arrays of strings (keys in objects0 and/or numbers (array
       indices.

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

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

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

       Note  that  the  path  expressions  are  not  different   from   normal
       expressions.  The  expression  path(..|select(type=="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"]

   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, 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.

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

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

   map(x), map_values(x)
       For  any  filter x, map(x) will run that filter for each element of the
       input array, and  produce  the  outputs  a  new  array.  map(.+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}

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

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

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

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

           jq ´add´
              []
           => null

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

   [Requires 1.5] flatten, flatten(depth)
       The filter flatten takes as  input  an  array  of  nested  arrays,  and
       produces  a  flat  array  in which all arrays inside the original array
       have been recursively  replaced  by  their  values.  You  can  pass  an
       argument to it to specify how many 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
       increment of by.

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

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

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

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

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

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

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

           jq ´floor´
              3.14159
           => 3

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

           jq ´sqrt´
              9
           => 3

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

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

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

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

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

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

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

       Note that division by zero raises an error.

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

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

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

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

       ·   null

       ·   false

       ·   true

       ·   numbers

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

       ·   arrays, in lexical order

       ·   objects

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

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

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

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

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

   group_by(path_expression)
       group_by(.foo)  takes as input an array, groups the elements having the
       same .foo field into separate arrays, and 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
       specify a particular field or property to  examine,  e.g.  min_by(.foo)
       finds the object with the smallest foo field.

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

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

   unique, unique_by(path_exp)
       The  unique  function  takes as input an array and produces an array of
       the same elements, in sorted order, with 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
       substring of A. An array B is contained in an array A if  all  elements
       in  B  are  contained  in any element in A. An object B is contained in
       object A if all of the values in B are contained in the value in A with
       the same key. All other types are assumed to be contained in each other
       if they are equal.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   implode
       The inverse of explode.

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

   split
       Splits an input string on the separator argument.

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

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

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

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

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

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

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

   until(cond; next)
       The  until(cond;  next)  function  allows  you  to repeatedly apply the
       expression next, initially to . then to its own 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
       structure, 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
       without concerns about recursion depth.

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

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

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

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

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

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

   ..
       Short-hand  for recurse without arguments. This is intended to resemble
       the XPath // operator. Note that ..a does not work; use  ..|a  instead.
       In  the  example  below  we use ..|.a? to find all the values of object
       keys "a" in any object found "below" ..

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

   env
       Outputs an object representing jq´s environment.

           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
       backslash.  Whatever  the  expression returns will be interpolated into
       the string.

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

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

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

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

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

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

       @text:

              Calls tostring, see that function for details.

       @json:

              Serializes the input as JSON.

       @html:

              Applies HTML/XML escaping, by mapping the  characters  <>&´"  to
              their entity equivalents &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
              double quotes for strings, and quotes escaped by repetition.

       @tsv:

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

       @sh:

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

       @base64:

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

       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´"

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

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

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

       The todate builtin is an alias for todateiso8601.

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

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

       The gmtime builtin consumes a number of seconds since  the  Unix  epoch
       and  outputs a "broken down time" representation of time as an array of
       numbers representing (in this order): the year, the month (zero-based),
       the  day of the month, the hour of the day, the minute of the hour, the
       second of the minute, the day of the week, and the day of the  year  --
       all one-based unless otherwise stated.

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

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

       The strftime(fmt) builtin formats a time with the given format.

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

       jq may not support some or all  of  this  date  functionality  on  some
       systems.

           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

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, it is  considered  "true"
       if  any  of  those  results  is  not false or null. If it produces zero
       results, it´s considered false.

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

           jq ´if . == 0 then

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

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

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

           jq ´. < 5´
              2
           => true

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

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

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

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

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

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

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

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

   Alternative operator - //
       A  filter  of  the  form  a  //  b produces the same results as a, if a
       produces results other than false and null. 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
       sometimes  used  in  Python  (jq´s or operator is reserved for strictly
       Boolean operations).

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

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

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

   ? 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:

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

       ·   i - Case insensitive search

       ·   m - Multi line mode (´.´ will match newlines)

       ·   n - Ignore empty matches

       ·   p - Both s and m modes are enabled

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

       ·   l - Find longest possible matches

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

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

       ·   test( "a\sb", "x" ).

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

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

       evaluates to: true, true, false, false.

   [Requires 1.5] 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

   [Requires 1.5] match(val), match(regex; flags)
       match  outputs  an  object  for  each  match it finds. Matches have the
       following fields:

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

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

       ·   string - the string that it matched

       ·   captures - an array of objects representing capturing groups.

       Capturing group objects have the following fields:

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

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

       ·   string - the string that was captured

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

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

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

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

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

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

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

   [Requires 1.5] 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" }

   [Requires 1.5] 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.

   [Requires 1.5] splits(regex), splits(regex; flags)
       These provide the same results as their split counterparts,  but  as  a
       stream instead of an array.

   [Requires 1.5] sub(regex; tostring) sub(regex; string; flags)
       Emit  the  string obtained by replacing the first match of regex in the
       input string with tostring, after interpolation. tostring should  be  a
       jq  string,  and  may  contain  references to named captures. The named
       captures are, in effect, 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)".

   [Requires 1.5] 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.

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

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

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

           length as $array_length | add / $array_length

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

       Suppose we have an array of  blog  posts,  with  "author"  and  "title"
       fields,  and  another  object  which is used to map 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
       providing a pattern that matches the structure of the  input  (this  is
       known as "destructuring"):

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

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

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

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

       will work, but

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

       won´t.

       For  programming  language theorists, it´s more accurate to say that jq
       variables are lexically-scoped bindings. In 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
       function  (in  fact,  this  is how some of the builtins are defined). A
       function may take arguments:

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

       Arguments are passed as filters, not as values. The same  argument  may
       be  referenced  multiple times with different inputs (here f is run for
       each element of the input array). Arguments to  a  function  work  more
       like  callbacks  than  like  value  arguments.  This  is  important  to
       understand. Consider:

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

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

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

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

       Or use the short-hand:

           def addvalue($f): ...;

       With either definition, addvalue(.foo) will  add  the  current  input´s
       .foo field to each element of the array.

       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.

           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]]

   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

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

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

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

       The nth(n; expr) function extracts the nth value output by  expr.  This
       can  be  defined  as  def nth(n; expr): last(limit(n + 1; expr));. Note
       that nth(n; expr) doesn´t support negative values of n.

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

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

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

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

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

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

   Recursion
       As described above, recurse uses recursion, and any jq function can  be
       recursive. The while builtin is also 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
       example,  .[]  generates  all the values in its input (which must be an
       array or an object), range(0; 10) generates the integers between 0  and
       10, and so on.

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

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

       All jq functions can be generators just by using builtin generators. It
       is  also possible to define new generators 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
       recursive call by _range to itself is in  tail  position.  The  example
       shows   off   three   advanced   topics:   tail   recursion,  generator
       construction, and sub-functions.

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

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

MATH

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

       Besides  simple  arithmetic  operators  such  as  +,  jq  also has most
       standard 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 ..

       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.

I/O

       At  this  time  jq  has  minimal support for I/O, mostly in the form of
       control 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.

       One builtin provides minimal output capabilities, debug. (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.

   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.

   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
       fashion, allowing jq programs to  start  processing  large  JSON  texts
       immediately 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 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,
       without 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
       just  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).

       All  the  assignment  operators  in  jq  have  path  expressions on the
       left-hand side.

   =
       The filter .foo = 1 will take as input an object and produce as  output
       an  object  with  the  "foo"  field  set  to  1.  There is no notion of
       "modifying"  or  "changing"  something  in  jq  -  all  jq  values  are
       immutable. For instance,

       .foo = .bar | .foo.baz = 1

       will  not  have  the side-effect of setting .bar.baz to be set to 1, as
       the similar-looking  program  in  Javascript,  Python,  Ruby  or  other
       languages  would.  Unlike  these  languages  (but like Haskell and some
       other functional languages), there  is  no  notion  of  two  arrays  or
       objects being "the same array" or "the same object". They can be equal,
       or not equal, but if we change one of them in no circumstances will the
       other change behind our backs.

       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.

       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 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 below) do not do this.

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

   |=
       As well as the  assignment  operator  ´=´,  jq  provides  the  "update"
       operator  ´|=´,  which  takes a filter on the right-hand side and works
       out the new value for the property of . being assigned  to  by  running
       the  old  value through this expression. For instance, .foo |= .+1 will
       build an object with the "foo" field set to the input´s "foo" plus 1.

       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}. The latter will set the "a"
       field of the input to the "a" field´s "b" field, producing {"a": 10}.

       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 multiple values, only the last one  will
       be 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]]

   +=, -=, *=, /=, %=, //=
       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.

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

   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
       produce multiple results, referring to different points  in  the  input
       document:

           .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
       executing 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
       operation. 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.

BUGS

       Presumably. Report them or discuss them at:

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

AUTHOR

       Stephen Dolan <mu@netsoc.tcd.ie>

                                 October 2015                            JQ(1)