MV command and change file namn

I need do add a text (string) to existing filename.

Example:

File before: 4827392021.xml
File after name change: finish4827392021.xml

how can i do this with MV command?

For one file: mv 4827392021.xml finish4827392021.xml.

But if you mean how to do this en masse, it's not possible.

But it's easy to script this using for example PowerShell script with WinSCP .NET assembly.

I have added an example to the documentation:
https://winscp.net/eng/docs/library_example_advanced_rename