Jq stuff

merge_objs.sh

#!/bin/bash
jq -s 'add | group_by(.id) | [.[] | reduce . as $item ({ "id": "", "prop1": "", "iface": "" }; { "id": $item.[0].id, "prop1": $item.[0].prop1, "iface": $item.[1].prop2[0].ifa
ce })]' obj1.json obj2.json > output.json

obj1.json

[
  {
    "id": "id1",
    "prop1": "test1",
    "to_remove": "remove me"
  },
  {
    "id": "id2",
    "prop1": "test2",
    "to_remove": "remove me"
  },
  {
    "id": "id3",
    "prop1": "test3",
    "to_remove": "remove me"
  }
]

obj2.json

[
  {
    "id": "id1",
    "prop2": [
      {
        "iface": "value1"
      }
    ]
  },
  {
    "id": "id2",
    "prop2": [
      {
        "iface": "value2"
      }
    ]
  },
  {
    "id": "id3",
    "prop2": [
      {
        "iface": "value3"
      }
    ]
  }
]

output.json

[
  {
    "id": "id1",
    "prop1": "test1",
    "iface": "value1"
  },
  {
    "id": "id2",
    "prop1": "test2",
    "iface": "value2"
  },
  {
    "id": "id3",
    "prop1": "test3",
    "iface": "value3"
  }
]