GRUB 2

Config

/etc/boot/grub2/grub.cfg

Save Default

/etc/default/grub

GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true

Quick update:

echo "GRUB_SAVEDEFAULT=true" >> /etc/default/grub
grub2-mkconfig -o /boot/grub2/grub.cfg

References:

• dual boot - How to get grub2 to remember last choice? - Ask Ubuntu - http://askubuntu.com/questions/148662/how-to-get-grub2-to-remember-last-choice

Chain Loader

menuentry "Fedora (chainload)" {
    savedefault
    insmod ext2
    insmod chain
    set root=(hd0,msdos1)
    chainloader +1
}

Disable OS Prober

echo "GRUB_DISABLE_OS_PROBER=true" >> /etc/default/grub
grub2-mkconfig -o /boot/grub2/grub.cfg