error "grub-mkconfig: You must run this as root"

Question

I am running Ubuntu 16. I got this error every time I try to run the update-grub command.

Answer 1

Just solved it: in Ubuntu this command does not work:

su -i

instead, I used

sudo -i 

After that I exported these paths:

export PATH=/usr/sbin:/usr/bin:/sbin:/bin

then

update-grub