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The HEAD action retrieves metadata from an object without returning the object itself. This action is useful if you're only interested in an object's metadata. To use HEAD, you must have READ access to the object.
A HEAD request has the same options as a GET action on an
object. The response is identical to the GET response except that there
is no response body. Because of this, if the HEAD request generates an
error, it returns a generic 404 Not Found or 403 Forbidden
code. It is not possible to retrieve the exact exception beyond these error codes.
If you encrypt an object by using server-side encryption with customer-provided encryption keys (SSE-C) when you store the object in Amazon S3, then when you retrieve the metadata from the object, you must use the following headers:
x-amz-server-side-encryption-customer-algorithm
x-amz-server-side-encryption-customer-key
x-amz-server-side-encryption-customer-key-MD5
For more information about SSE-C, see Server-Side Encryption (Using Customer-Provided Encryption Keys).
Encryption request headers, like x-amz-server-side-encryption, should
not be sent for GET requests if your object uses server-side encryption with KMS keys
(SSE-KMS) or server-side encryption with Amazon S3–managed encryption keys (SSE-S3).
If your object does use these types of keys, you’ll get an HTTP 400 BadRequest error.
The last modified property in this case is the creation date of the object.
Request headers are limited to 8 KB in size. For more information, see Common Request Headers.
Consider the following when using request headers:
Consideration 1 – If both of the If-Match and If-Unmodified-Since
headers are present in the request as follows:
If-Match condition evaluates to true, and;
If-Unmodified-Since condition evaluates to false;
Then Amazon S3 returns 200 OK and the data requested.
Consideration 2 – If both of the If-None-Match and If-Modified-Since
headers are present in the request as follows:
If-None-Match condition evaluates to false, and;
If-Modified-Since condition evaluates to true;
Then Amazon S3 returns the 304 Not Modified response code.
For more information about conditional requests, see RFC 7232.
Permissions
You need the relevant read object (or version) permission for this operation. For more information, see Specifying Permissions in a Policy. If the object you request does not exist, the error Amazon S3 returns depends on whether you also have the s3:ListBucket permission.
If you have the s3:ListBucket permission on the bucket, Amazon S3 returns
an HTTP status code 404 ("no such key") error.
If you don’t have the s3:ListBucket permission, Amazon S3 returns an
HTTP status code 403 ("access denied") error.
The following actions are related to HeadObject:
This is an asynchronous operation using the standard naming convention for .NET 4.5 or higher. For .NET 3.5 the operation is implemented as a pair of methods using the standard naming convention of BeginGetObjectMetadata and EndGetObjectMetadata.
Namespace: Amazon.S3
Assembly: AWSSDK.S3.dll
Version: 3.x.y.z
public virtual Task<GetObjectMetadataResponse> GetObjectMetadataAsync( String bucketName, String key, CancellationToken cancellationToken )
The name of the bucket containing the object. When using this action with an access point, you must direct requests to the access point hostname. The access point hostname takes the form AccessPointName-AccountId.s3-accesspoint.Region.amazonaws.com. When using this action with an access point through the Amazon Web Services SDKs, you provide the access point ARN in place of the bucket name. For more information about access point ARNs, see Using access points in the Amazon S3 User Guide. When using this action with Amazon S3 on Outposts, you must direct requests to the S3 on Outposts hostname. The S3 on Outposts hostname takes the form AccessPointName-AccountId.outpostID.s3-outposts.Region.amazonaws.com. When using this action with S3 on Outposts through the Amazon Web Services SDKs, you provide the Outposts bucket ARN in place of the bucket name. For more information about S3 on Outposts ARNs, see Using Amazon S3 on Outposts in the Amazon S3 User Guide.
The object key.
A cancellation token that can be used by other objects or threads to receive notice of cancellation.
.NET Core App:
Supported in: 3.1
.NET Standard:
Supported in: 2.0
.NET Framework:
Supported in: 4.5