Hello @Velu prasath - Welcome to Microsoft Q&A Forum, thank you for posting your query here!
I believe you are referring to connecting Azure Blob Storage over SFTP. Please confirm if the understand is correct.
The SFTP username is storage_account_name.username. The combination of both is used for the SFTP command. This is also explained in the below link with an example as well: https://learn.microsoft.com/en-us/azure/storage/blobs/secure-file-transfer-protocol-support-how-to?tabs=azure-portal#connect-an-sftp-client
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