Booting the installation

Installing CentOS from the DVD1 ISO is the easiest and the recommended method of performing a standard RHEL installation. Other installation methods require additional setup and configuration. For example, when installing CentOS on a large number of systems simultaneously, the best approach is to boot from a PXE server and install from a source in a shared network location.

After you have created a bootable USB, DVD, or CD you are ready to boot the CentOS installation.

Types of boot options

There are two types of boot options; those with an equals "=" sign, and those without an equals "=" sign. Boot options are appended to the boot command line and multiple options must be separated by a single space. Boot options that are specific to the installation program always start with inst.

Options with an equals "=" sign

You must specify a value for boot options that use the = symbol. For example, the inst.vncpassword= option must contain a value, in this case, a password. The correct syntax for this example is inst.vncpassword=password.

Options without an equals "=" sign

This boot option does not accept any values or parameters. For example, the rd.live.check option forces the installation program to verify the installation media before starting the installation. If this boot option is present, the verification is performed; if the boot option is not present, the verification is skipped.

Editing boot options

This section contains information about the different ways that you can edit boot options from the boot menu. The boot menu opens after you boot the installation media.

Editing the boot: prompt in BIOS

When using the boot: prompt, the first option must always specify the installation program image file that you want to load. In most cases, you can specify the image using the keyword. You can specify additional options according to your requirements.

Prerequisites

  • You have created bootable installation media (USB, CD or DVD).

  • You have booted the installation from the media, and the installation boot menu is open.

Procedure

  1. With the boot menu open, press the Esc key on your keyboard.

  2. The boot: prompt is now accessible.

  3. Press the Tab key on your keyboard to display the help commands.

  4. Press the Enter key on your keyboard to start the installation with your options. To return from the boot: prompt to the boot menu, restart the system and boot from the installation media again.

The boot: prompt also accepts dracut kernel options. A list of options is available in the dracut.cmdline(7) man page.

Editing the > prompt

You can use the > prompt to edit predefined boot options. For example, select Test this media and install CentOS 8 from the boot menu to display a full set of options.

This procedure is for BIOS-based AMD64 and Intel 64 systems.
Prerequisites

  • You have created bootable installation media (USB, CD or DVD).

  • You have booted the installation from the media, and the installation boot menu is open.

Procedure

  1. From the boot menu, select an option and press the Tab key on your keyboard. The > prompt is accessible and displays the available options.

  2. Append the options that you require to the > prompt.

  3. Press the Enter key on your keyboard to start the installation.

  4. Press the Esc key on your keyboard to cancel editing and return to the boot menu.

Editing the GRUB2 menu

The GRUB2 menu is available on UEFI-based AMD64, Intel 64, and 64-bit ARM systems.

Prerequisites

  • You have created bootable installation media (USB, CD or DVD).

  • You have booted the installation from the media, and the installation boot menu is open.

Procedure

  1. From the boot menu window, select an option and press the e key on your keyboard.

  2. When you finish editing, press F10 or Ctrl+X on your keyboard to start the installation using the specified options.

Booting the installation from a USB, CD, or DVD

Follow the steps in this procedure to boot the CentOS installation using a USB, CD, or DVD. The following steps are generic. Consult your hardware manufacturer’s documentation for specific instructions.

Prerequisite

You have created bootable installation media (USB, CD or DVD). See Creating installation media for more information.

Procedure

  1. Power off the system to which you are installing CentOS.

  2. Disconnect any drives from the system.

  3. Power on the system.

  4. Insert the bootable installation media (USB, DVD, or CD).

  5. Power off the system but do not remove the boot media.

  6. Power on the system.

    You might need to press a specific key or combination of keys to boot from the media or configure the Basic Input/Output System (BIOS) of your system to boot from the media. For more information, see the documentation that came with your system.

  7. The CentOS 8 boot window opens and displays information about a variety of available boot options.

  8. Use the arrow keys on your keyboard to select the boot option that you require, and press Enter to select the boot option. The Welcome to CentOS 8 window opens and you can install CentOS using the graphical user interface.

    The installation program automatically begins if no action is performed in the boot window within 60 seconds.

  9. Optional: For UEFI-based systems, press E to edit the available boot options. For BIOS-based systems, press the Tab key on your keyboard to edit the available boot options. The boot window enters edit mode and you can change the predefined command line to add or remove boot options.

    1. Press Enter to confirm your choice.

Additional Resources

Booting the installation from a network using PXE

Follow the steps in this procedure to boot the CentOS installation from a network using PXE.

Prerequisites

  • You have configured a TFTP server, and there is a network interface in your system that supports PXE. See Additional resources for more information.

  • You have configured your system to boot from the network interface. This option is in the BIOS, and can be labeled Network Boot or Boot Services.

  • You have verified that the BIOS is configured to boot from the specified network interface. Some BIOS systems specify the network interface as a possible boot device, but do not support the PXE standard. See your hardware’s documentation for more information. When you have properly enabled PXE booting, the system can boot the CentOS 8 installation program without any other media.

Procedure

To boot the installation process from a network using PXE, you must use a physical network connection, for example, Ethernet. You cannot boot the installation process with a wireless connection.

  1. Verify that the network cable is attached. The link indicator light on the network socket should be lit, even if the computer is not switched on.

  2. Switch on the system.

    Depending on your hardware, some network setup and diagnostic information can be displayed before your system connects to a PXE server. When connected, a menu is displayed according to the PXE server configuration.

  3. Press the number key that corresponds to the option that you require.

    In some instances, boot options are not displayed. If this occurs, press the Enter key on your keyboard or wait until the boot window opens.

    The CentOS 8 boot window opens and displays information about a variety of available boot options.

  4. Use the arrow keys on your keyboard to select the boot option that you require, and press Enter to select the boot option. The Welcome to CentOS 8 window opens and you can install CentOS using the graphical user interface.

    The installation program automatically begins if no action is performed in the boot window within 60 seconds.

  5. Optional: For UEFI-based systems, press E to edit the available boot options. For BIOS-based systems, press the Tab key on your keyboard to edit the available boot options. The boot window enters edit mode and you can change the predefined command line to add or remove boot options.

    1. Press Enter to confirm your choice.

Additional Resources