efibootmgr:tldr:b86f5

The efibootmgr command is a utility tool that is used in EFI-based systems (Extensible Firmware Interface) to manage the EFI boot entries (also known as boot variables) in the system's firmware.

In simplest terms, EFI is a firmware specification that provides the interface between the operating system and the platform firmware on the computer. It replaces the older BIOS (Basic Input/Output System) firmware. EFI boot entries store information about various boot options in a non-volatile storage area within the system's firmware.

The efibootmgr command allows users to view, create, modify, or delete these EFI boot entries. It provides a command-line interface to interact with the system's EFI boot manager. Some common uses of efibootmgr include:

1. Listing boot entries: Running efibootmgr without any additional options will display a list of all the current EFI boot entries along with their respective boot order.

2. Changing boot order: The efibootmgr -o option allows users to rearrange the boot order of the entries, specifying the new order using the boot entry numbers.

3. Creating new boot entries: efibootmgr -c is used to create a new EFI boot entry by specifying the necessary boot parameters such as the boot device, bootloader path, and boot description.

4. Modifying existing boot entries: The efibootmgr -t option can be used to change the timeout value for boot entry selection during system startup.

5. Deleting unwanted boot entries: Using efibootmgr -b followed by the boot entry number will remove the specified boot entry from the EFI boot list.

It's important to exercise caution when using efibootmgr as incorrect modifications to the EFI boot entries can potentially render the system unbootable.