====== Grub 2 ======
===== FACTS =====
od verze 2.00 se nejak sere...prej /boot neni ext3.. takze instaluju s --force --recheck
a pote nutno zamknout soubor core.img (aby se neposunul, jinak se to podela jak lilo...bug)
<code bash>
# chattr +i /boot/grub2/i386-pc/core.img
</code>
zmeny do /etc/default/grub
===== Zmena kernel boot options =====
https://fedoraproject.org/wiki/GRUB_2#Updating_the_GRUB_configuration_file
==== do Fedora 33 ====
  - upravime ///etc/default/grub//
  - pregenerujeme vlastni config<code bash>
# grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
</code>
==== Fedora 33+ ====
<WRAP info>Boot options jsou ulozene v //grubenv// souboru, takze nestaci manualni zmena v ///boot/grub2.grub.cfg//.

Dale se zmenila cesta ke konfiguracnimu souboru, puvodni je pouze "include" noveho!</WRAP>
  - upravime ///etc/default/grub//
  - pregenerujeme vlastni config<code bash>
# grub2-mkconfig -o /boot/grub2/grub.cfg
</code>

===== VYPNUTI OSTATNICH OS [ OS-PROBER ] =====
  * edit /etc/default/grub; add lines / modify value:
<code ini>
GRUB_DISABLE_OS_PROBER="true"
</code>
  * vygenerujeme znovu konfiguraci
<code bash>
sudo grub2-mkconfig > /boot/grub2/grub.cfg
</code>

===== Preskoceni systemu z boot menu =====
  * do /etc/default/grub pridat
<code ini>
GRUB_OS_PROBER_SKIP_LIST="4E26E10726E0F13F@/dev/sda1 07a6db3e-fed0-1e8e-c1b3-548e3bd90d64@/dev/sda6"
</code>
  * vygenerujeme znovu konfiguraci
<code bash>
sudo grub2-mkconfig > /boot/grub2/grub.cfg
</code>

===== PREINSTALACE Z LIVECD =====
<WRAP alert>
Plati pro disk **/dev/sda** kde je Linux nainstalovan na oddilu **/dev/sda7**.
</WRAP>

<code bash>
sudo mount /dev/sda7 /mnt
sudo mount --bind /dev /mnt/dev
sudo mount --bind /dev/pts /mnt/dev/pts
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
grub-install /dev/sda
update-grub
exit
sudo umount /mnt/{dev/pts,dev,proc,sys}
sudo reboot # restartuje okamzite, nebo restartuj rucne :)
</code>


===== GRAFIKA =====
[ http://forums.fedoraforum.org/showthread.php?t=276691 ]

  * vypsani dostupnych grafickych modu:

v grub command prompt
<code>
# set pager=1
# insmod vbe
#vbeinfo
</code>
  * do /etc/default/grub
<code ini>
GRUB_VIDEO_BACKEND="vbe"
GRUB_TERMINAL_OUTPUT="gfxterm"
#GRUB_FONT_PATH="/boot/grub2/themes/system/DejaVuSans-Bold-14.pf2"
#GRUB_FONT_PATH="/boot/grub2/themes/system/DejaVuSans-10.pf2"
#GRUB_FONT_PATH="/boot/grub2/themes/system/DejaVuSans-12.pf2"
GRUB_FONT_PATH="/boot/grub2/fonts/DejaVuSansMono-24.pf2"
#GRUB_BACKGROUND="/boot/grub2/themes/system/background.png"
GRUB_BACKGROUND="/boot/grub2/fonts/background-sized.png"
#GRUB_THEME="/boot/grub2/themes/system/theme.txt"
GRUB_GFXMODE="1280x720x32"
#GRUB_GFXPAYLOAD_LINUX=keep #text for troubles
</code>

===== ISO BOOT =====
<WRAP alert>
!!! hlavne musi umet iso, napr debian live iso
</WRAP>

  * custom.cfg nebo (cistejsi) /etc/grub.d/40_custom
==== UBUNTU ====
<code>
submenu "BackTrack 5 R2 KDE ISO"{
menuentry "BackTrack Text - Persistent CUDA Boot Text Mode" --class ubuntu --class gnu-linux --class gnu --class os {
        savedefault
        load_video
        set gfxpayload=1280x800x32
        insmod gzio
        insmod part_msdos
        insmod ntfs
        insmod ext2
        echo 'Loading BackTrack 5 R2 iso'
	# z BACKTRACK DVD hlavne musi byt zkopirovany adresar /casper (!!!v grub2 se partition pocitaji od 1!!! /dev/sda1 = hd0,msdos1)
        linux (hd0,msdos7)/bt/casper/vmlinuz boot=casper persistent live-media-path=/bt/casper/ text splash intel_iommu=off
        echo 'Loading initial ramdisk ...'
        initrd   (hd0,msdos7)/bt/casper/initrdcuda.gz
}
}
</code>
==== DEBIAN ====
<code>
menuentry "${title}" {
${grub_prep}
        iso_path="${rel_dirname}/${grml}"
        export iso_path
        kernelopts=" $CUSTOM_BOOTOPTIONS $additional_param "
        export kernelopts
        loopback loop "${rel_dirname}/$grml"
        set root=(loop)
        configfile /boot/grub/loopback.cfg
}
</code>