Application for Data transfer (USB to USB)

I need to have a standalone software for Linux that will go on a ARM (raspberry pi or similar) computer. I need the application to boot automaticly (no acces to the desktop) and have a custom image bootloader when we turn on the device. I absolutly don't want to see any Linux screen on the device. I need to have acces to the serial of the device and it's for transfer from one serial to another. So I need to have a application that I will be able to mount 2 usb drive, select from the first drive and copy to the second drive. I don't want to be able to format the drive, but I want to be able to have full acces to the fils on the USB. To be able to copy 100% of the file on the first usb drive. I'll add the photo of the bootloader when I will find the freelancer that will do the project. Last, I want a GUI application and touch screen frendly. It's will go on a small screen device.