where is the nrfutil log file

[zeroking5]

Hi Nodic team

    Now I word wrong with the nrfutil to upgrade the firmware

    I want to have a look of the nrfutil log file,But I can't find that 

   so would you please tell me where is the nrfutil file

   need your help 

[zeroking5]

note:where is the nrfutil log file