如何使用jq或其他工具从Json输出中获得最需要的行“DBInstanceIdentifier”

Question

这是Json:我试着用

jq -r '.[] | .DBSnapshotIdentifier'

但对我来说不管用

{
    "DBSnapshots": [
        {
            "DBSnapshotIdentifier": "auto-lims-final-snapshot",
            "DBInstanceIdentifier": "auto-lims",
            "SnapshotCreateTime": "2018-08-15T09:59:23.332000+00:00",
            "Engine": "postgres",
            "AllocatedStorage": 50,
            "Status": "available",
            "Port": 5432,
            "AvailabilityZone": "us-east-2a",
            "VpcId": "vpc-e799fc8f",
            "InstanceCreateTime": "2018-04-09T08:28:03.565000+00:00",
            "MasterUsername": "postgres",
            "EngineVersion": "9.6.6",
            "LicenseModel": "postgresql-license",
            "SnapshotType": "manual",
            "OptionGroupName": "default:postgres-9-6",
            "PercentProgress": 100,
            "StorageType": "gp2",
            "Encrypted": false,
            "DBSnapshotArn": "arn:aws:rds:us-east-2:833682533595:snapshot:auto-lims-final-snapshot",
            "IAMDatabaseAuthenticationEnabled": false,
            "ProcessorFeatures": [],
            "DbiResourceId": "db-ZL5T2TA2PJVG6CVOJRO7HUOAXQ",
            "TagList": [
                {
                    "Key": "Environment",
                    "Value": "auto"
                },
                {
                    "Key": "Application",
                    "Value": "LIMS"
                }
            ],
            "SnapshotTarget": "region"
        },
        {
            "DBSnapshotIdentifier": "automation-lims-before-postgres-12-5",
            "DBInstanceIdentifier": "automation-lims",
            "Engine": "postgres",
            "AllocatedStorage": 500,
            "Status": "available",
            "Port": 5432,
            "AvailabilityZone": "us-east-2b",
            "VpcId": "vpc-09fa88d2884ee2083",
            "InstanceCreateTime": "2019-12-26T11:19:41.947000+00:00",
            "MasterUsername": "lims",
            "EngineVersion": "9.6.20",
            "LicenseModel": "postgresql-license",
            "SnapshotType": "manual",
            "OptionGroupName": "default:postgres-9-6",
            "PercentProgress": 100
        }
    ]
}

我怎么能只得到嵌套行。

Answer 1

首先需要选择DBSnapshots对象，尝试：

.DBSnapshots[] | .DBSnapshotIdentifier

这将产生以下结果：

"auto-lims-final-snapshot"
"automation-lims-before-postgres-12-5"

您可以尝试使用in this online demo

要包含.TagList.Key，我们可以添加以下内容：

.DBSnapshots[] | .DBSnapshotIdentifier, .TagList[]?.Key

现在这将输出

"auto-lims-final-snapshot"
"Environment"
"Application"
"automation-lims-before-postgres-12-5"

您可以尝试使用in this online demo

如果您希望DBSnapshotIdentifier与TagList位于同一条线上，我们可以使用字符串插值，如下所示：

.DBSnapshots[] | "\(.DBSnapshotIdentifier) - \(.TagList[]?.Key)"

Thiis将输出：

"auto-lims-final-snapshot - Environment"
"auto-lims-final-snapshot - Application"

this demo演示

上面命令中的.[]?表示：

与.[]类似，但是如果.不是数组或对象，则不会输出错误。

更多信息in JQ's documentation