Problem while installing nvidia drivers please help

[hack.root//T]

This is my problem, I download Kali 1.0.6 and installed it on my 16GB USB and added persistence using this tutorial

http://docs.kali.org/installation/kali-linux-live-usb-install

but I wanted to try installing Cuda and here where the problems started.

I followed this tutorial

http://docs.kali.org/general-use/install-nvidia-drivers-on-kali-linux

I managed to run these command without a problem:

apt-get update
apt-get dist-upgrade
apt-get install -y linux-headers-$(uname -r)
apt-get install nvidia-kernel-dkms

But when i try to run this command:

sed 's/quiet/quiet nouveau.modeset=0/g' -i /etc/default/grub

the terminal says it cant find /etc/default/grub which is making me so angry this is my 10th time trying to bypass this problem but i cant find a clue anywhere can someone help me please?

[hcorsted]

Can you find the grub there? Can you not edit it manually?

[hack.root//T]

no there is no grub there

[maverik35]

Do you have Grub in USB?....Unless you have installed grub I do not see how you can do that. I might be wrong, but in USB is isolinux or syslinux or other bootloader. Unless you install grub.

[hack.root//T]

i only did what the tutorial said, how do i install grub in my live usb is there a way