Extract a specific field from JSON output using jq

jq-notes.md

{
  "example": {
    "sub-example": [
      {
        "name": "123-345",
        "tag" : 100
      },
      {
        "name": "234-456",
        "tag" : 100
      },
      {
        "name": "4a7-a07a5",
        "tag" : 100
      }
    ]
  }
}

If you just want to extract the name fields, the command you're looking for is jq '.example."sub-example" | .[] | .name'. If you want to keep the names in an array, wrap the whole jq expression in square brackets.

to get length

jq '.example."sub-example" | length'

source: https://stackoverflow.com/a/39228718