RHEL: Adding a boot entry to GRUB/GRUB2 configuration

# Tested on RHEL 6 & 7


# RHEL 6
# ------------------------------------------------------------------------------------------

# Adding a new entry to grub boot file is as simple as adding a new boot stanza, at the end
# of the file, to /boot/grub/grub.conf

# To modify the default boot entry, we have to change the 'default' option to point to the
# the new stanza. We can use entry position (zero-based numbering):


vi /boot/grub/grub.conf
[...]
default=1
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.32-358.el6.i686)
        root (hd0,0)
        kernel /vmlinuz-2.6.32-358.el6.i686 ro root=/dev/mapper/rootvg-lv_root [...]
        initrd /initramfs-2.6.32-358.el6.i686.img
title CentOS - Backup ramdisk image
        root (hd0,0)
        kernel /vmlinuz-2.6.32-358.el6.i686 ro root=/dev/mapper/rootvg-lv_root [...]
        initrd /initramfs-2.6.32-358.el6.i686.img.bak




# RHEL 7
# ------------------------------------------------------------------------------------------

# RHEL 7 uses grub2 and /boot/grub2/grub.cfg config file, instead of the old grub.conf
# format.

# The new grub.cfg file is not intended for direct editing. Rather we have to modify the
# source file and run the grub2-mkconfig command to generate it.

# The sources files are /etc/default/grub and the scripts under /etc/grub.d/

# If we want to add a new custom entry to boot menu, we have to add a boot stanza to
# /etc/grub.d/40_custom. These stanzas will look like this:

menuentry "CentOS - Backup ramdisk image" {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_msdos
        insmod ext2
        set root='hd0,msdos1'
        linux16 /vmlinuz-3.10.0-327.el7.i686 root=/dev/mapper/rootvg-lv_root ro crashkernel=auto [...]
        initrd16 /initramfs-3.10.0-327.el7.i686.img.bak
    }
menuentry "Another boot entry" {
        set root=(hd0,1)
        linux /vmlinuz-3.09-custom
        initrd /initrd-3.09-custom.img
    }

# To modify the default boot entry, we have to change the GRUB_DEFAULT option in
# /etc/default/grub to point to the new stanza we added. We can use entry position
# (zero-based numbering) or by name:

GRUB_DEFAULT="CentOS - Backup ramdisk image"

# or # GRUB_DEFAULT=2


# Default value of GRUB_DEFAULT is 'saved' which points to /boot/grub2/grubenv file.


# Once finished, we have to run following command in order to re-generate
# /boot/grub2/grub.cfg file:

grub2-mkconfig -o /boot/grub2/grub.cfg

0 (0)
Article Rating (No Votes)
Rate this article
Attachments
There are no attachments for this article.
Comments
There are no comments for this article. Be the first to post a comment.
Full Name
Email Address
Security Code Security Code
Related Articles RSS Feed
stunnel bacula
Viewed 1151 times since Fri, Sep 28, 2018
RHEL: How to change a USER/GROUP UID/GID and all owned files
Viewed 13045 times since Sat, Jun 2, 2018
How To Use Systemctl to Manage Systemd Services and Units
Viewed 5404 times since Mon, Dec 7, 2020
Turbocharge PuTTY with 12 Powerful Add-Ons – Software for Geeks #3
Viewed 11525 times since Sun, Sep 30, 2018
Kernel sysctl configuration file for Linux
Viewed 2519 times since Fri, Aug 3, 2018
OpenSSL – sprawdzanie czy klucz pasuje do certyfikatu
Viewed 1637 times since Thu, May 24, 2018
How to encrypt a partition with DM-Crypt LUKS on Linux
Viewed 1409 times since Fri, Jul 13, 2018
stunnel: Authentication
Viewed 7871 times since Fri, Sep 28, 2018
LVM: Extend an existing Volume Group by adding a new disk
Viewed 1118 times since Sat, Jun 2, 2018
RHEL: Extending a multipath LUN
Viewed 2546 times since Sun, May 27, 2018