is it possible to display CRC64NVME calculated during s3 upload ?

[chipitsine]

we do massive "aws s3 cp "
our disk io does not allow us to read files extra time.

is it possible to tell aws cli something like "please calculate CRC64NVME during upload of certain object and tell me" ?

[uldyssian-sh]

AWS CLI v2 already calculates a CRC-based checksum during aws s3 cp uploads (CRC64NVME is the default), but the high-level aws s3 commands do not have a supported flag that prints “the checksum value I just computed” as part of normal output.

The practical way to get the CRC64NVME for the uploaded object without re-reading the file is:

1. Upload as you do today (optionally force the algorithm, though it’s already the default):

aws s3 cp /path/to/file s3://my-bucket/my-key --checksum-algorithm CRC64NVME

2. Query the stored checksum from S3 with a HEAD request (no extra disk I/O, only network):

aws s3api head-object
--bucket my-bucket
--key my-key
--query ChecksumCRC64NVME
--output text

If you truly need to see the computed value “during” the upload, the only workaround is --debug and scraping the request headers (you will see the x-amz-checksum-crc64nvme header), but that is not a stable/clean interface and is not recommended for automation.

Summary:

AWS CLI can compute CRC64NVME during upload, but it does not print it as normal output.
Use head-object after upload to retrieve ChecksumCRC64NVME without reading the file again.

[uldyssian-sh]

Thanks! If this helps, please consider marking it as “Helpful” or “Accepted” 😊