grub 2 notes and examples
NOTE: grub = grAND uNIFIED bOOT LOADER
editing grub is not recommended. better to use your LIVE install CD/DVD from SuSE or MINT and let it attempt
to make any edits or repairs during install or update. If your attempt fails that way, the next option would be
to use a GUI tool from the desktop to edit the BOOTLOADER - provided of course you can log in.
If you can't log in, then your next options are to boot up with the LIVE version of the CD/DVD, or use Gparted.
see: http://johnmeister.com/linux/Notes/Gparted-for-Recovery/ALL.html
BEFORE EDITING: /usr/bin/cp /boot/grub2/grub.cfg /boot/grub2/grub.cfg.`date +'%Y%m%d-%H'`
(or cp /boot/grub2/grub.cfg /boot/grub2/grub.cfg.`date +'%Y%m%d-%H'`
or cp grub.cfg grub.cfg.`date +'%Y%m%d-%H'` )
you could create a short "wrapper" script, e.g. "vicp.sh" and use it safely copy grub.cfg
vi vicp.sh
#!/bin/bash
# vicp.sh - created 2015-09-01 jm - wrapper script to copy files before and after edit
# note: $1 represents the 1st positional parameter, aka, the file to edit using vi.
/usr/bin/cp $1 $1.before-`date +'%Y%m%d-%H%M'`
##################################################################################
# if desired, add an archive Directory path to copied file name, e.g.
# uncomment the following 2 lines and comment out the line above this comment
# mkdir BAK
# /usr/bin/cp $1 BAK/$1.before-`date +'%Y%m%d-%H%M'`
##################################################################################
/usr/bin/vi $1
/usr/bin/cp $1 $1.after-`date +'%Y%m%d-%H%M'`
##################################################################################
# if desired, add an archive Directory path to copied file name, e.g.
# uncomment the following 2 lines and comment out the line above this comment
# /usr/bin/cp $1 BAK/$1.after-`date +'%Y%m%d-%H%M'`
##################################################################################
/usr/bin/ls -l $1*
/usr/bin/ls -l BAK/$1*
make it executable and put it in your "bin" directory:
------------------------------------------------
--> chmod 744 vicp.sh
------------------------------------------------
--> which vicp.sh
/home/luser/bin/vicp.sh
------------------------------------------------
(you could also drop the .sh, so you'd only have to type: vicp /boot/grub2/grub.cfg )
EXAMPLE:
--> vicp /boot/grub2/grub.cfg
-rw------- 1 luser users 324 Sep 1 15:39 /boot/grub2/grub.cfg
-rw------- 1 luser users 324 Sep 1 15:39 /boot/grub2/grub.cfg.after-20150901-1539
-rw------- 1 luser users 325 Sep 1 15:39 /boot/grub2/grub.cfg.before-20150901-1539
The safest thing to edit in grub.cfg is the timeout:
if [ x${boot_once} = xtrue ]; then
set timeout=0
elif sleep --interruptible 0 ; then
set timeout=8
fi
changing timeout=8 to timeout=30 would be a safe thing to do... about the ONLY safe thing.
If you only want to edit the listing in the menu, or change the default time, that can be done relatively safely.
If you want to eliminate an option within grub, you must remember that each menu entry represents an option, and if
the default is set to say number 4, and you eliminate number 3, grub will select what was number 5, no number 5, problems.
editing other parts are a bit riskier... next in line...
The following is a menuentry, it begins with the first line, the details within the braces {} are important, do NOT edit those unless
you understand exactly what each line does.
I would not edit the first line, except for the very first item in single quotes: 'openSUSE 13.1' - and then I'd try it to make sure it was ok. The next line you might edit, carefully, is "set root=" This points to the hard drive and partition. Grub used msdosX to represent the partitions.
You might also be able to edit the "echo" commands. But make a copy first, test it, and then used a LIVE Linux disk to replace the edited version with the copy.
menuentry 'openSUSE 13.1' --class 'opensuse-13-1' --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-0145a9fd-da51-4d7a-9e5a-424651c15925' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2' 0145a9fd-da51-4d7a-9e5a-424651c15925
else
search --no-floppy --fs-uuid --set=root 0145a9fd-da51-4d7a-9e5a-424651c15925
fi
echo 'Loading Linux 3.11.10-29-desktop ...'
linux /boot/vmlinuz-3.11.10-29-desktop root=UUID=0145a9fd-da51-4d7a-9e5a-424651c15925 video=1024x768 resume=/dev/disk/by-id/ata-ST2000DM001-1CH164_Z1F3VFP3-part1 splash=silent quiet showopts
echo 'Loading initial ramdisk ...'
initrd /boot/initrd-3.11.10-29-desktop
}
If absolutely needed, you can edit the "root" field in a menuentry topoint to the correct partition. However, unless the technical details are the same you risk corruption of the
sysetm on a boot. If the entry is correct except for the hard drive number, e.g. hd0 became hd1 because another disk was added, but nothing else changed you might be ok. YMMV.
set root='hd0,msdos2' --> set root='hd1,msdos2'
However, using grub-mkcfg would be safer from within the OS. This is one area where one really needs to RTM!
sample copy of /boot/grub2/grub.cfg file (owned completely by root)
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub2-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#
### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
load_env
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="${saved_entry}"
fi
if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi
export menuentry_id_option
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi
function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}
if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_msdos
insmod ext2
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2' 0145a9fd-da51-4d7a-9e5a-424651c15925
else
search --no-floppy --fs-uuid --set=root 0145a9fd-da51-4d7a-9e5a-424651c15925
fi
font="/usr/share/grub2/unicode.pf2"
fi
if loadfont $font ; then
set gfxmode=auto
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=en_US
insmod gettext
fi
terminal_output gfxterm
insmod part_msdos
insmod ext2
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2' 0145a9fd-da51-4d7a-9e5a-424651c15925
else
search --no-floppy --fs-uuid --set=root 0145a9fd-da51-4d7a-9e5a-424651c15925
fi
insmod gfxmenu
loadfont ($root)/boot/grub2/themes/openSUSE/DejaVuSans-Bold14.pf2
loadfont ($root)/boot/grub2/themes/openSUSE/DejaVuSans10.pf2
loadfont ($root)/boot/grub2/themes/openSUSE/DejaVuSans12.pf2
loadfont ($root)/boot/grub2/themes/openSUSE/ascii.pf2
insmod png
set theme=($root)/boot/grub2/themes/openSUSE/theme.txt
export theme
if [ x${boot_once} = xtrue ]; then
set timeout=0
elif sleep --interruptible 0 ; then
set timeout=8
fi
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/10_linux ###
menuentry 'openSUSE 13.1' --class 'opensuse-13-1' --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-0145a9fd-da51-4d7a-9e5a-424651c15925' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2' 0145a9fd-da51-4d7a-9e5a-424651c15925
else
search --no-floppy --fs-uuid --set=root 0145a9fd-da51-4d7a-9e5a-424651c15925
fi
echo 'Loading Linux 3.11.10-29-desktop ...'
linux /boot/vmlinuz-3.11.10-29-desktop root=UUID=0145a9fd-da51-4d7a-9e5a-424651c15925 video=1024x768 resume=/dev/disk/by-id/ata-ST2000DM001-1CH164_Z1F3VFP3-part1 splash=silent quiet showopts
echo 'Loading initial ramdisk ...'
initrd /boot/initrd-3.11.10-29-desktop
}
submenu 'Advanced options for openSUSE 13.1' $menuentry_id_option 'gnulinux-advanced-0145a9fd-da51-4d7a-9e5a-424651c15925' {
menuentry 'openSUSE 13.1, with Linux 3.11.10-29-desktop' --class 'opensuse-13-1' --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.11.10-29-desktop-advanced-0145a9fd-da51-4d7a-9e5a-424651c15925' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2' 0145a9fd-da51-4d7a-9e5a-424651c15925
else
search --no-floppy --fs-uuid --set=root 0145a9fd-da51-4d7a-9e5a-424651c15925
fi
echo 'Loading Linux 3.11.10-29-desktop ...'
linux /boot/vmlinuz-3.11.10-29-desktop root=UUID=0145a9fd-da51-4d7a-9e5a-424651c15925 video=1024x768 resume=/dev/disk/by-id/ata-ST2000DM001-1CH164_Z1F3VFP3-part1 splash=silent quiet showopts
echo 'Loading initial ramdisk ...'
initrd /boot/initrd-3.11.10-29-desktop
}
menuentry 'openSUSE 13.1, with Linux 3.11.10-29-desktop (recovery mode)' --class 'opensuse-13-1' --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.11.10-29-desktop-recovery-0145a9fd-da51-4d7a-9e5a-424651c15925' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2' 0145a9fd-da51-4d7a-9e5a-424651c15925
else
search --no-floppy --fs-uuid --set=root 0145a9fd-da51-4d7a-9e5a-424651c15925
fi
echo 'Loading Linux 3.11.10-29-desktop ...'
linux /boot/vmlinuz-3.11.10-29-desktop root=UUID=0145a9fd-da51-4d7a-9e5a-424651c15925 showopts apm=off noresume edd=off powersaved=off nohz=off highres=off processor.max_cstate=1 nomodeset x11failsafe
echo 'Loading initial ramdisk ...'
initrd /boot/initrd-3.11.10-29-desktop
}
menuentry 'openSUSE 13.1, with Linux 3.11.10-25-desktop' --class 'opensuse-13-1' --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.11.10-25-desktop-advanced-0145a9fd-da51-4d7a-9e5a-424651c15925' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2' 0145a9fd-da51-4d7a-9e5a-424651c15925
else
search --no-floppy --fs-uuid --set=root 0145a9fd-da51-4d7a-9e5a-424651c15925
fi
echo 'Loading Linux 3.11.10-25-desktop ...'
linux /boot/vmlinuz-3.11.10-25-desktop root=UUID=0145a9fd-da51-4d7a-9e5a-424651c15925 video=1024x768 resume=/dev/disk/by-id/ata-ST2000DM001-1CH164_Z1F3VFP3-part1 splash=silent quiet showopts
echo 'Loading initial ramdisk ...'
initrd /boot/initrd-3.11.10-25-desktop
}
menuentry 'openSUSE 13.1, with Linux 3.11.10-25-desktop (recovery mode)' --class 'opensuse-13-1' --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.11.10-25-desktop-recovery-0145a9fd-da51-4d7a-9e5a-424651c15925' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos2 --hint-efi=hd0,msdos2 --hint-baremetal=ahci0,msdos2 --hint='hd0,msdos2' 0145a9fd-da51-4d7a-9e5a-424651c15925
else
search --no-floppy --fs-uuid --set=root 0145a9fd-da51-4d7a-9e5a-424651c15925
fi
echo 'Loading Linux 3.11.10-25-desktop ...'
linux /boot/vmlinuz-3.11.10-25-desktop root=UUID=0145a9fd-da51-4d7a-9e5a-424651c15925 showopts apm=off noresume edd=off powersaved=off nohz=off highres=off processor.max_cstate=1 nomodeset x11failsafe
echo 'Loading initial ramdisk ...'
initrd /boot/initrd-3.11.10-25-desktop
}
}
### END /etc/grub.d/10_linux ###
### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###
### BEGIN /etc/grub.d/20_memtest86+ ###
### END /etc/grub.d/20_memtest86+ ###
### BEGIN /etc/grub.d/20_ppc_terminfo ###
### END /etc/grub.d/20_ppc_terminfo ###
### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###
### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###
### BEGIN /etc/grub.d/41_custom ###
if [ -f ${config_directory}/custom.cfg ]; then
source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
### BEGIN /etc/grub.d/90_persistent ###
### END /etc/grub.d/90_persistent ###
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