If your system do not show grub menu, hold down SHIFT key on system start to show grub menu.
To press c to enter grub command line.
Show grub command prompt results paginated, run
set pager=1
ls command shows all available partitions. To see files in a partition, use ls (hd0,1)/
cat command can be used to display content of a file. Example: cat (hd0,1)/etc/issue
set command is used to set settings. If you don’t specify any value, it print out existing settings.
Setting kernel and booting up
grub> set root=(hd0,1) grub> linux /boot/vmlinuz-3.13.0-29-generic root=/dev/sda1 grub> initrd /boot/initrd.img-3.13.0-29-generic grub> boot
To generate grub.cfg on CentOS 7, run
grub2-mkconfig -o /boot/grub2/grub.cfg
Rebuild/Update grub.cfg
On Debian
root@hon-vpn:~# update-grub Generating grub configuration file ... Found background image: /usr/share/images/desktop-base/desktop-grub.png Found linux image: /boot/vmlinuz-3.16.0-4-amd64 Found initrd image: /boot/initrd.img-3.16.0-4-amd64 done root@hon-vpn:~#
View All Menu entry
CentOS/RHEL
grep menuentry /boot/grub2/grub.cfg
Debian/Ubuntu
grep menuentry /boot/grub/grub.cfg
