GRUB

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

Dual Boot - Remember Last Choice

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

Ubuntu:

/etc/default/grub

# GRUB_DEFAULT=0
GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true

# GRUB_TIMEOUT=0
GRUB_TIMEOUT=60

note the GRUB_SAVEDEFAULT line needs to be added

then run:

sudo update-grub

To force a default for next boot use:

# list menu options
awk -F\' '/menuentry / {print $2}' /boot/grub/grub.cfg

# specify default boot option
grub-set-default "some-boot-menu-option"

grub-set-default Ubuntu

grub-set-default 0

NOTE: tab auto complete also works with grub-set-default!!

See grub-menu.sh

GRUB Legacy

See GRUB Legacy