Verified Environment

Version
OSUbuntu 20.04.5 LTS
jqjq-1.6

What to do

Note

–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.

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

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

Examples

[
  ["key1", "key2", "key3"],
  ["aa", "bb", "cc"],
  ["dd", "ee", "ff"],
  ["gg", "hh", "ii"],
  ["jj", "kk", "ll"]
]

#!/bin/bash

jq '.[0] as $headers | .[1:][] | with_entries(.key = $headers[.key])' ${1} | jq -s .

bash convert.sh example.json

[
  {
    "key1": "aa",
    "key2": "bb",
    "key3": "cc"
  },
  {
    "key1": "dd",
    "key2": "ee",
    "key3": "ff"
  },
  {
    "key1": "gg",
    "key2": "hh",
    "key3": "ii"
  },
  {
    "key1": "jj",
    "key2": "kk",
    "key3": "ll"
  }
]

Explanation

.[0] as $headers

[ "key1", "key2", "key3" ]

.[1:][]

[ "aa", "bb", "cc" ]
[ "dd", "ee", "ff" ]
[ "gg", "hh", "ii" ]
[ "jj", "kk", "ll" ]

with_entries(.key = $headers[.key]) = to_entries | map(.key = $headers[.key]) | from_entries

to_entries

[
  { "key": 0, "value": "aa" },
  { "key": 1, "value": "bb" },
  { "key": 2, "value": "cc" }
]
[
  { "key": 0, "value": "dd" },
  { "key": 1, "value": "ee" },
  { "key": 2, "value": "ff" }
]
[
  { "key": 0, "value": "gg" },
  { "key": 1, "value": "hh" },
  { "key": 2, "value": "ii" }
]
[
  { "key": 0, "value": "jj" },
  { "key": 1, "value": "kk" },
  { "key": 2, "value": "ll" }
]

to_entries | map(.key = $headers[.key]

[
  { "key": "key1", "value": "aa" },
  { "key": "key2", "value": "bb" },
  { "key": "key3", "value": "cc" }
]
[
  { "key": "key1", "value": "dd" },
  { "key": "key2", "value": "ee" },
  { "key": "key3", "value": "ff" }
]
[
  { "key": "key1", "value": "gg" },
  { "key": "key2", "value": "hh" },
  { "key": "key3", "value": "ii" }
]
[
  { "key": "key1", "value": "jj" },
  { "key": "key2", "value": "kk" },
  { "key": "key3", "value": "ll" }
]

to_entries | map(.key = $headers[.key]) | from_entries

{ "key1": "aa", "key2": "bb", "key3": "cc" }
{ "key1": "dd", "key2": "ee", "key3": "ff" }
{ "key1": "gg", "key2": "hh", "key3": "ii" }
{ "key1": "jj", "key2": "kk", "key3": "ll" }

jq -s .

[
  { "key1": "aa", "key2": "bb", "key3": "cc" }
  { "key1": "dd", "key2": "ee", "key3": "ff" }
  { "key1": "gg", "key2": "hh", "key3": "ii" }
  { "key1": "jj", "key2": "kk", "key3": "ll" }
]