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21.3. Making Temporary Changes to a GRUB 2 Menu

Procedure 21.1. Making Temporary Changes to a Kernel Menu Entry
To change kernel parameters only during a single boot process, proceed as follows:
  1. Start the system and, on the GRUB 2 boot screen, move the cursor to the menu entry you want to edit, and press the e key for edit.
  2. Move the cursor down to find the kernel command line. The kernel command line starts with linux on 64-Bit IBM Power Series, linux16 on x86-64 BIOS-based systems, or linuxefi on UEFI systems.
  3. Move the cursor to the end of the line.
    Press Ctrl+a and Ctrl+e to jump to the start and end of the line, respectively. On some systems, Home and End might also work.
  4. Edit the kernel parameters as required. For example, to run the system in emergency mode, add the emergency parameter at the end of the linux16 line:
    linux16      /vmlinuz-4.2.0-1.fc23.x86_64 root=/dev/mapper/fedora-root ro crashkernel=auto rd.luks=0 vconsole.keymap=us rhgb quiet emergency
    The rhgb and quiet parameters can be removed in order to enable system messages.
    These settings are not persistent and apply only for a single boot. To make persistent changes to a menu entry on a system, use the grubby tool. See the section called “Adding and Removing Arguments from a GRUB Menu Entry” for more information on using grubby.