i have an old mac mini which i am replacing with a new mac mini i have to unplug one to plug in the other. any advice how to transfer data and files?

Hello, Sherlock2021.

Congrats on getting that new Mac mini.

The best way to transfer your data from the old Mac to the new will be to use Migration Assistant and a Time Machine backup on an external drive from the moment you first begin to setup the new Mac.

Backup the old Mac to the drive before you set up your new mini. Then connect the drive to the new Mac, startup the new Mac and step through the setup process. At the point that you are asked if you want to transfer data, select yes and from a TIme Machine backup. Follow the prompts to completion.

Back up your Mac with Time Machine - Apple Support

Move your content to a new Mac - Apple Support

Thanks for your advice. Since I do not own those Additional bits of hardware, I guess I’m out of luck?

You aren't necessarily out of luck. Beg or borrow a small monitor or tv and a USB keyboard and mouse to use with the old mini. That way you can use Migration Assistant between the two Macs. It's more cumbersome than using a small external drive, but it's an option.

To be honest, this is a perfect opportunity for you to buy an external drive, that's all the extra hardware you need. It doesn't have to be expensive and it would definitely be worth the cost when trouble strikes and in situations like this one that you're in now.

You really should prioritize putting in place a Time Machine backup plan with your new Mac. These forums are full of threads that involve users losing some or all of their data, or having trouble upgrading or restoring their Macs only because they don't have backup. It's easily avoided.

You're welcome. Good luck.🍀