In Red Hat EL versions 5 and 6 we can easily to update the /etc/grub.conf
in case we want to change the kernel by default variable
For example , grub.conf on redhat 5
default=0
timeout=5
#splashimage=(hd0,0)/grub/splash.xpm.gz
#hiddenmenu
title Red Hat Enterprise Linux Server (2.6.18-410.el5)
root (hd0,0)
kernel /vmlinuz-2.6.18-410.el5 ro root=/dev/rootvg/slash
initrd /initrd-2.6.18-410.el5.img
title Red Hat Enterprise Linux Server (2.6.18-409.el5)
root (hd0,0)
kernel /vmlinuz-2.6.18-409.el5 ro root=/dev/rootvg/slash
initrd /initrd-2.6.18-409.el5.img
From this /etc/grub.conf
if we want to boot from kernel 2.6.18-409
version
then we just change the default=1
.
So on the next boot, the OS will start with the old kernel
RHEL7 is very different. I find in the RHEL7 the /boot/grub2/grub.cfg
But I don't understand how to change the file in order to boot from other kernel as I do it on RHEL5.