Book Image

CentOS 7 Linux Server Cookbook - Second Edition

By : Jonathan Hobson
Book Image

CentOS 7 Linux Server Cookbook - Second Edition

By: Jonathan Hobson

Overview of this book

This book will provide you with a comprehensive series of starting points that will give you direct access to the inner workings of the latest CentOS version 7 and help you trim the learning curve to master your server. You will begin with the installation and basic configuration of CentOS 7, followed by learning how to manage your system, services and software packages. You will then gain an understanding of how to administer the file system, secure access to your server and configure various resource sharing services such as file, printer and DHCP servers across your network. Further on, we cover advanced topics such as FTP services, building your own DNS server, running database servers, and providing mail and web services. Finally, you will get a deep understanding of SELinux and you will learn how to work with Docker operating-system virtualization and how to monitor your IT infrastructure with Nagios. By the end of this book, you will have a fair understanding of all the aspects of configuring, implementing and administering CentOS 7 Linux server and how to put it in control.
Table of Contents (22 chapters)
CentOS 7 Linux Server Cookbook Second Edition
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Index

Getting started and customising the boot loader


When you turn on your computer, the boot loader is the first program that starts up and is responsible for loading and transferring control to an underlying operating system. Nowadays, almost any modern Linux distribution uses the GRand Unified Bootloader version 2 (GRUB2) for starting the system. It has a lot of flexibility in configuration and supports a lot of different operating systems. In this recipe, we will show how to customize the GRUB2 boot loader by disabling the waiting time of the menu display and therefore improving the time it takes for booting the system.

Getting ready

To complete this recipe, you will require access to an already installed CentOS 7 operating system (minimal or any other CentOS 7 installation type will work) with root privileges. Also, you need to have some basic experiences with a text based editor, such as nano, for changing the configuration files.

How to do it...

We begin this recipe by opening the main GRUB2 configuration file with our text editor of choice and modifying it.

  1. First log in as root into your system and create a copy of the GRUB2 configuration file for backup and rollback, if needed. Press the Return key to finish:

    cp /etc/default/grub /etc/default/grub.BAK
    
  2. Open the main GRUB2 configuration file that we want to edit with the following command and press the Return key (here we will use the editor nano, if you have not installed it yet type yum install nano):

    nano /etc/default/grub
    
  3. Press the Return key in the first line where the cursor is at to insert a new line at the top, and then insert the following line:

    GRUB_HIDDEN_TIMEOUT=0
    
  4. Add a # sign to the beginning of the following line, as shown:

    GRUB_TIMEOUT=0
    
  5. Now save the file in the nano using Ctrl+o (and Return to confirm the filename to save). Use Ctrl+x to exit the editor and then run the following command:

    dmesg | grep -Fq "EFI v"
    
  6. If the preceding command does not produce any output, run the following command:

    grub2-mkconfig -o /boot/grub2/grub.cfg
    
  7. Otherwise, if there is an output, run:

    grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
    
  8. If grub2-mkconfig is successful, it will print Done. Now reboot your system using the following command:

    reboot
    
  9. During the rebooting process, you will notice that the GRUB2 boot menu will not appear any more and the system will boot up faster.

How it works...

Having completed this recipe, we now know how to customize the GRUB2 boot loader. In this very easy recipe, we only showed you very basic modifications to the boot loader but it can do much more! It supports a broad variety of filesystems and can boot almost any compatible operating system. This is also particularly useful if you plan to run multiple operating systems on the same machine. To learn more about GRUB2's configuration file syntax type the info grub2 | less command and go to the section 6.1 Simple configuration handling (read the recipe Navigating text files with less in Chapter 2, Configuring the System to learn how to browse this document).