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# cp etc/grdnt_hid.udev /etc/udev/rules.d/95-grdnt_hid.rules
You need superuser privileges to write in the /etc/udev/rules.d folder
The mentioned rules prescribe udev to set read and write rights for a device file representing the Guardant dongle in the system. This allows assigning the dongle with the privileges of any user on the system.