In dual-boot system (Win 10 and Kali), whenever Win 10 is updated , the Grub is replaced by window boot manager.

The Grub can be recovered with the Kali live boot USB.

After boot process with Kali live, check the linux and EFI partitions.

# fdisk -l 

In my case, 

EFI partition ==> /dev/sda1

Linux partition ==> /dev/sda7

keep that in mind,

# mount /dev/sda7 /mnt

# mount --bind /dev /mnt/dev

# mount --bind /dev/pts /mnt/dev/pts

# mount --bind /proc /mnt/proc

# mount --bind /sys /mnt/sys

# mount --bind /dev/sda1 /mnt/boot/efi

# chroot /mnt /bin/bash

# grub-install /dev/sda

# update-grub

# exit

# umount /mnt/boot/efi

# umount /mnt/sys

# umount /mnt/proc

# umount /mnt/dev/pts

# umount /mnt/dev

# umount /mnt

# shutdown -h 0 -r

After reboot, you can see the grub entry, but window partition might not be seen,

Thus, after boot up, do "update-grub" again, 

$ sudo update-grub

Then, after next boot, you can see the window boot manager in Grub entry .

"secure-delete" consists of four tools : srm (the secure version of rm), sdmem (wiping memory), sfill (wiping free space in HDD), sswap (wiping swap partition)

$ apt-get install secure-delete

$ srm <path to the file>

==> by default, srm overwrites the content 38 times. you can add a final iteration of zeros as before, with the -z option

==> and recursively with -r option

$ sdmem

$ cat /proc/swaps

$ swapoff </dev/XXX>

$ sswap </dev/XXX>

$ swapon </dev/XXX>

because I'm familiar with CentOS, i couldn't set default kernel easily in grub.cfg in kali(debian) linux

basically, there is main menu which in turns, includes submenu.

what I want to do is setting default kernel to third entry in submenu within secondary entry in main menu.

here is the example

$ vim  /etc/default/grub

and set GRUB_DEFAULT="1>2"

$ sudo update-grub 

...

After update "/etc/apt/sources.list"

$ apt-get update

$ apt-get dist-upgrade

Reference : https://superuser.com/questions/79822/how-to-swap-the-fn-use-of-function-keys-on-an-apple-keyboard-in-linux

echo X > /sys/module/hid_apple/parameters/fnmode

if X == 0 : Fn key disabled

X == 1 : Fn key pressed by default

X == 2 : Fn key released by default

From /drivers/hid/hid-apple.c