EDIT GRUB CENTOS 7 HOW TO
EDIT GRUB CENTOS 7 CODE

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EDIT GRUB CENTOS 7 HOW TO

In Exercise 17-2, you learn how to apply modifications to the GRUB 2 configuration and write them to the /boot/grub2/grub.cfg configuration file. On a BIOS system, the command would be grub2-mkconfig -o /boot/grub2/grub.cfg, and on a UEFI system the command would be grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg. To write the modified configuration to the appropriate files, you use the grub2-mkconfig command and redirect its output to the appropriate configuration file. Type man 7 bootparam for a man page that contains an excellent description of all boot parameters that you may use while starting the kernel. There are many of them, and most of them you’ll never use, but it is good to know where you can find them. While working with GRUB 2, you need to know a bit about kernel boot arguments. If your server runs on physical hardware that takes a long time to get through the BIOS checks, it may be interesting to increase this time a bit. This defines the amount of time your server waits for you to access the GRUB 2 boot menu before it continues booting automatically. Without these you will not have to guess why your server takes a long time after a restart you’ll just be able to see.Īnother interesting parameter is GRUB_TIMEOUT. To accomplish this, it is a good idea to remove the rhgb and quiet boot options. On the exam, you want to know immediately if something does not work out well. That is nice to hide confusing messages for end users, but if you are a server administrator, you probably just want to remove these options. These options tell the kernel to hide all output while booting. Some likely candidates for removal are the options rhgb and quiet. In this line, you can apply permanent fixes to the GRUB 2 configuration. The most important line in this file is GRUB_CMDLINE_LINUX, which defines how the Linux kernel should be started. To apply modifications to the GRUB 2 boot loader, the file /etc/default/grub is your entry point. Do not edit it, as this file is automatically generated. After making modifications to the GRUB 2 configuration, you’ll need to regenerate the relevant configuration file, which is why you should know the name of the file that applies to your system architecture. On a UEFI system the file is written to /boot/efi/EFI/redhat. If your system is a BIOS system, the name of the file is /boot/grub2/grub.cf. Understanding GRUB 2 Configuration Filesīased on the configuration files mentioned previously, the main configuration file is created. GRUB 2 picks up new kernels automatically and adds them to the boot menu automatically, so nothing has to be added manually. You also do not need to modify anything if you want the capability to select from different kernels while booting. You typically do not have to modify these files.

EDIT GRUB CENTOS 7 CODE

In these files, you’ll find rather complicated shell code that tells GRUB what to load and how to load it. That is the most important part of the GRUB 2 configuration anyway.Īpart from the configuration in /etc/default/grub, there are a few configuration files in /etc/grub.d. For the RHCSA exam, make sure that you understand the contents of the /etc/default/grub file.

Edit grub centos 7