Linux: setting permissions for USB serial ports using udev rules

USBIt’s pretty annoying that, by default, USB serial devices come up with somewhat restricted permissions. Sometimes adding the user to the dialout  group works, sometimes it doesn’t. The most reliable way to fix this for all time is to add a udev rule but I can never remember the syntax, hence this post…

Create a file called something like 66-tty.rules in /etc/udev/rules.d. Add the line:

KERNEL=="ttyUSB*",MODE="0666"

The next time the device is plugged in, it will pick up the correct permissions.