jqコマンドの高度な使い方

jqコマンドとは

キーを取得する

a.json

{
  "key1": {
    "Sub-Key11": "Value11",
    "Sub-Key12": "Value12"
  },
  "key2": {
    "Sub-Key21": "Value21",
    "Sub-Key22": "Value22"
  }
}

% jq -r 'keys[]' a.json 
key1
key2

キーを追加する

% jq '. |= .+{"key": {"Sub-Key13": "Value31", "Sub-Key23": "Value32"}}' a.json 
{
  "key1": {
    "Sub-Key11": "Value11",
    "Sub-Key12": "Value12"
  },
  "key2": {
    "Sub-Key21": "Value21",
    "Sub-Key22": "Value22"
  },
  "key": {
    "Sub-Key13": "Value31",
    "Sub-Key23": "Value32"
  }
}

Keyをkey, Valueをvalueとして抽出する

% jq -r 'to_entries[]| .' ~/.a.json
{
  "key": "key1",
  "value": {
    "Sub-Key11": "Value11",
    "Sub-Key12": "Value12"
  }
}
{
  "key": "key2",
  "value": {
    "Sub-Key21": "Value21",
    "Sub-Key22": "Value22"
  }
}

CSVにする

[
  {
    "Key": "key1",
    "Value": "value1"
  },
  {
    "Key": "key2",
    "Value": "value2"
  }
]

jq -r '.[] | [.Key, .Value] | @tsv' b.jaon 
key1    value1
key2    value2

% jq '.[]' a.json 
{
  "Sub-Key11": "Value11",
  "Sub-Key12": "Value12"
}
{
  "Sub-Key21": "Value21",
  "Sub-Key22": "Value22"
}

キーと子要素を同じ階層にする

as で特定の変数を記録する

キーを配列にして、変数にキーをセットしてみると予想通りにハッシュ配列が取れる

% jq '. as $e | keys[] | $e[.]' a.json 
{
  "Sub-Key11": "Value11",
  "Sub-Key12": "Value12"
}
{
  "Sub-Key21": "Value21",
  "Sub-Key22": "Value22"
}

そこにキーを加算すると

% jq '. as $top | keys[] | {"Key": .} + $top[.]' a.json 
{
  "Key": "key1",
  "Sub-Key11": "Value11",
  "Sub-Key12": "Value12"
}
{
  "Key": "key2",
  "Sub-Key21": "Value21",
  "Sub-Key22": "Value22"
}