If you have bought a computer in the last couple of years then most likely it did not come with any COM ports on it. But you can purchase these really nice USB to serial connections that work great. Sometime however when you plug one into a linux computer it will pick an random unused COM port and you don’t know which one. I personally use PuTTY and I need to know the exact port in order for the serial connection to work.

You can use the simple command dmesg | grep tty and you can see which tty ports are being used. When I run this command I received the following output.

[268868.081185] usb 5-2: pl2303 converter now attached to ttyUSB0

This is telling me that my serial connection is using ttyUSB0 and now I know what to type into PuTTY to get my serial connection.