Knowledge Base:Adjusting GRUB settings for a single boot session

Synopsis
When troubleshooting boot failures or trying to make changes for kernel settings, users might want to boot their system with a particular change in the GRUB bootloader configuration for a single boot session (i.e. not persistent).

Environment
Gentoo Linux systems using GRUB as the bootloader.

Analysis
With GRUB, it is possible to boot with different settings for just a single boot session. Changes made herein are not persisted, so rebooting afterwards will boot back using the "old" configuration settings.

Resolution

 * 1) During bootup, wait until the GRUB boot menu is displayed. The default timeout for GRUB is 30 seconds (if necessary press any key other than  or  to halt the timeout);
 * 2) Navigate to the entry desired boot from, but do not press the  key. Instead, press the  key (which stands for edit);
 * 3) Navigate to the line needed to be modified (which is most likely the one starting with , but can also be the   or   line) and press  again to edit this specific line. When finished changing the line, press the  key;
 * 4) When all required changes have been made to the line(s), press the  key to boot the entry.

If happy with the result, do not forget to update with changes made in the steps above for persistent result.