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    Object Storage Service:append-object

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    Object Storage Service:append-object

    Last Updated:Jun 22, 2026

    Uploads an object by appending data to it incrementally.

    Usage notes

    • The final object created by append-object cannot exceed 5 GB.

    • append-object does not support server-side encryption with Key Management Service (KMS) using a specified customer master key (CMK) ID.

    Permissions

    By default, an Alibaba Cloud account has full permissions. RAM users or RAM roles under an Alibaba Cloud account do not have any permissions by default. The Alibaba Cloud account or account administrator must grant operation permissions through RAM policies or Bucket Policy.

    API

    Action

    Description

    AppendObject

    oss:PutObject

    You can call this operation to upload an object by appending the object to an existing object.

    oss:PutObjectTagging

    When uploading an object by appending the object to an existing object, if you specify object tags through x-oss-tagging, this permission is required.

    Command syntax

    ossutil api append-object --bucket value --key value --position value [flags]

    Parameter

    Type

    Description

    --body

    string

    The request body.

    --bucket

    string

    The name of the bucket.

    --cache-control

    string

    The caching behavior for the object.

    --content-disposition

    string

    The display name of the object when downloaded.

    --content-encoding

    string

    The encoding format of the object.

    --content-md5

    string

    The MD5 hash of the object content, used to verify data integrity.

    --expires

    string

    The expiration time.

    --key

    string

    The full path of the object.

    --metadata

    stringArray

    The metadata of the object. Specify custom metadata with parameters prefixed by x-oss-meta-*.

    --object-acl

    string

    The access control list (ACL) of the object.

    --position

    string

    The position from which to start appending data, in bytes.

    --server-side-encryption

    string

    The server-side encryption method.

    --storage-class

    string

    The storage class of the object.

    --tagging

    string

    The tags of the object. You can specify multiple tags. Example: TagA=A&TagB=B.
    Note

    • The append-object command corresponds to the AppendObject API operation. For more information about the parameters of the API operation, see AppendObject.

    • For more information about supported global command-line options, see Global command-line options.

    Examples

    • Append a string to the object exampleobject.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body "hi oss"

    • Append data from a file to the object exampleobject.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body file://appendFile

    • Append a string to the object exampleobject with custom metadata.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body "hi oss" --metadata user=aliyun --metadata email=ali***@aliyuncs.com

    • Append a string to the object exampleobject with object tags.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body "hi oss" --tagging "TagA=A&TagB=B"

    • Append a string to the object exampleobject and set the ACL and storage class.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body "hi oss" --object-acl private --storage-class IA

    • Append a string to the object exampleobject with server-side encryption.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body "hi oss" --body "hi oss" --server-side-encryption AES256

    • Append a string and set the cache-control behavior for the object.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body "hi oss" --cache-control no-cache

    • Append a string and set the download filename for the object.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body "hi oss" --content-disposition "attachment;filename=oss_download.jpg"

    • Append a string to the object exampleobject with a Content-MD5 integrity check.

      ossutil api append-object --bucket examplebucket --key exampleobject --position 0 --body "hi oss" --content-md5 ohhnqLBJFiKkPSBO1eNaUA==