Protect files from accidental overwrites

Replacing a destination file can permanently remove its previous content. SFTPPlus MFT therefore treats overwrite handling as an explicit part of a managed file transfer workflow.

The same protection applies to automated client transfers and file processing event handlers, including archive creation, archive extraction, and file dispatching.

Choose what happens when a file already exists ​

The default rule is to fail the operation. The existing destination file remains unchanged, the source file is retained, and SFTPPlus records the failure for investigation.

Other workflows can use a different rule:

• Skip the source file: Keep the destination unchanged and emit an audit event stating that the file was skipped.
• Overwrite the destination: Replace the previous content and emit an audit event stating that an overwrite occurred. For client transfers, the event includes the size of the new data.
• Disable the existence check: Send the file without first checking whether the destination already exists. This is useful with remote servers that do not support the extra operation required for overwrite detection. The remote server and transfer protocol determine what happens to an existing file.

These choices let a workflow distinguish between a duplicate that should stop processing, a file that can safely be ignored, and an intentional replacement.

Keep both versions with timestamps ​

Automated client transfers provide three timestamp rules for retaining file versions:

• timestamp-always adds a timestamp to every transferred file.
• timestamp-to-new-file keeps the existing destination file under its original name and adds a timestamp to the new file only when a conflict occurs.
• timestamp-to-existing-file renames the existing destination file with a timestamp, then transfers the new file under the original name.

The final option is useful when another application always expects the current file at a fixed path but previous versions must remain available.

Apply protection to file processing ​

Overwrite rules also protect files created by processing event handlers. The archive creation and extraction handlers can fail, skip, or replace output files when the destination already contains the same name.

The file dispatcher applies the same rules when it copies or moves a file. It can also use timestamped names when each dispatched version needs to be retained.

Keep overwrite decisions in the audit trail ​

An overwrite or skip is not silent. SFTPPlus emits an event that identifies the transfer or event handler, the affected path, and the result. These events can be sent to the activity log, a dedicated log file, or an external monitoring service.

See the transfer configuration documentation for the complete overwrite_rule reference.