efibootmgr Command Linux: Complete Guide to EFI Boot Manager Control

The efibootmgr command is an essential Linux utility for managing EFI (Extensible Firmware Interface) boot entries on UEFI-enabled systems. This powerful tool allows system administrators to view, create, modify, and delete boot entries directly from the command line, making it indispensable for system configuration and troubleshooting.

What is efibootmgr?

The efibootmgr command is a userspace application that modifies the EFI Boot Manager. It can display current boot information, change the boot order, create new boot entries, and remove existing ones. This tool communicates directly with the system’s UEFI firmware through the EFI variables interface, making it a crucial component for modern Linux system management.

Prerequisites and Installation

Before using efibootmgr, ensure your system meets these requirements:

• UEFI-based system (not legacy BIOS)
• Linux kernel with EFI support enabled
• Root privileges for most operations

Installing efibootmgr

Most Linux distributions include efibootmgr in their repositories:

# Ubuntu/Debian
sudo apt update
sudo apt install efibootmgr

# CentOS/RHEL/Fedora
sudo dnf install efibootmgr
# or for older versions
sudo yum install efibootmgr

# Arch Linux
sudo pacman -S efibootmgr

Basic Syntax and Options

The basic syntax of efibootmgr follows this pattern:

efibootmgr [OPTIONS]

Common Options

Viewing Current Boot Configuration

To display the current EFI boot configuration, use the basic command without any options:

sudo efibootmgr

Example output:

BootCurrent: 0001
Timeout: 1 seconds
BootOrder: 0001,0000,0002,0003
Boot0000* Windows Boot Manager
Boot0001* Ubuntu
Boot0002* UEFI: Built-in EFI Shell
Boot0003* UEFI: USB Device

For more detailed information, use the verbose flag:

sudo efibootmgr -v

Verbose output example:

BootCurrent: 0001
Timeout: 1 seconds
BootOrder: 0001,0000,0002,0003
Boot0000* Windows Boot Manager	HD(1,GPT,12345678-1234-1234-1234-123456789012,0x800,0x32000)/File(\EFI\Microsoft\Boot\bootmgfw.efi)
Boot0001* Ubuntu	HD(1,GPT,87654321-4321-4321-4321-210987654321,0x800,0x32000)/File(\EFI\ubuntu\grubx64.efi)
Boot0002* UEFI: Built-in EFI Shell	VenHw(5023b95c-db26-429b-a648-bd47664c8012)
Boot0003* UEFI: USB Device	USB(1,0)/USB(0,0)

Managing Boot Order

Changing Boot Order

To modify the boot order, use the -o option followed by comma-separated boot entry numbers:

sudo efibootmgr -o 0001,0000,0002

This command sets the boot order to:

1. Boot0001 (Ubuntu)
2. Boot0000 (Windows Boot Manager)
3. Boot0002 (UEFI Shell)

Setting Next Boot Entry

To boot from a specific entry only on the next restart:

sudo efibootmgr -n 0000

This will boot from Boot0000 on the next restart, then return to the normal boot order.

Creating New Boot Entries

Creating a new boot entry requires several parameters. Here’s the basic syntax:

sudo efibootmgr -c -d /dev/sdX -p Y -L "Boot Label" -l "\EFI\path\to\bootloader.efi"

Example: Creating a Ubuntu Boot Entry

sudo efibootmgr -c -d /dev/sda -p 1 -L "Ubuntu 22.04" -l "\EFI\ubuntu\grubx64.efi"

Parameters explained:

• -c: Create a new entry
• -d /dev/sda: Boot device
• -p 1: EFI system partition number
• -L "Ubuntu 22.04": Boot entry label
• -l "\EFI\ubuntu\grubx64.efi": Path to bootloader

Creating Entry with Additional Parameters

You can add kernel parameters using the -u option:

sudo efibootmgr -c -d /dev/sda -p 1 -L "Ubuntu Debug" -l "\EFI\ubuntu\grubx64.efi" -u "quiet splash debug"

Deleting Boot Entries

To remove a boot entry, use the -B option with the boot number:

sudo efibootmgr -B -b 0003

This removes Boot0003 from the boot menu.

Removing Multiple Entries

To delete multiple entries, run the command for each:

sudo efibootmgr -B -b 0003
sudo efibootmgr -B -b 0004
sudo efibootmgr -B -b 0005

Advanced efibootmgr Usage

Activating and Deactivating Entries

You can activate a boot entry without deleting it:

sudo efibootmgr -b 0002 -a

To deactivate (but not delete) an entry:

sudo efibootmgr -b 0002 -A

Timeout Configuration

Set the boot menu timeout (in seconds):

sudo efibootmgr -t 10

To disable timeout (wait indefinitely):

sudo efibootmgr -t 0

Practical Examples and Use Cases

Dual Boot Setup

Setting up a dual-boot system with Windows and Linux:

# View current entries
sudo efibootmgr -v

# Create Linux entry
sudo efibootmgr -c -d /dev/sda -p 1 -L "Linux Mint" -l "\EFI\linuxmint\grubx64.efi"

# Set boot order (Linux first, then Windows)
sudo efibootmgr -o 0004,0000

Recovery Boot Entry

Creating a recovery boot entry for system maintenance:

sudo efibootmgr -c -d /dev/sda -p 1 -L "System Recovery" -l "\EFI\recovery\bootx64.efi"

Fixing Boot Issues

If your system won’t boot, you can recreate the boot entry from a live USB:

# Boot from live USB, then mount your system
sudo mount /dev/sda2 /mnt
sudo mount /dev/sda1 /mnt/boot/efi

# Chroot into your system
sudo chroot /mnt

# Recreate boot entry
efibootmgr -c -d /dev/sda -p 1 -L "Ubuntu Recovery" -l "\EFI\ubuntu\grubx64.efi"

Troubleshooting Common Issues

EFI Variables Not Accessible

If you get permission errors, ensure:

# Check if efivarfs is mounted
mount | grep efivarfs

# If not mounted, mount it
sudo mount -t efivarfs efivarfs /sys/firmware/efi/efivars

Boot Entry Not Appearing

Sometimes firmware ignores entries. Try:

# Check if entry exists but is inactive
sudo efibootmgr -v

# Activate the entry
sudo efibootmgr -b 0001 -a

# Update boot order
sudo efibootmgr -o 0001,0000

Secure Boot Issues

For systems with Secure Boot enabled, ensure your bootloader is properly signed or disable Secure Boot in UEFI settings.

Security Considerations

When using efibootmgr, consider these security aspects:

• Always run with sudo/root privileges
• Backup current boot configuration before making changes
• Verify bootloader paths exist before creating entries
• Be cautious with Secure Boot modifications

Integration with Other Tools

Working with GRUB

After modifying boot entries, update GRUB configuration:

sudo update-grub
# or
sudo grub-mkconfig -o /boot/grub/grub.cfg

Systemd-boot Integration

For systemd-boot users:

sudo bootctl status
sudo bootctl update

Best Practices

1. Backup First: Always record current boot configuration before modifications
2. Test Changes: Verify boot entries work before making permanent changes
3. Use Descriptive Labels: Choose clear, informative names for boot entries
4. Regular Maintenance: Periodically clean unused boot entries
5. Document Changes: Keep records of customizations for future reference

Conclusion

The efibootmgr command is an indispensable tool for managing UEFI boot configurations in Linux. From simple boot order changes to complex dual-boot setups, mastering this utility enables precise control over your system’s boot process. Whether you’re a system administrator managing multiple machines or a user fine-tuning your personal setup, efibootmgr provides the flexibility and power needed for effective boot management.

Remember to always exercise caution when modifying boot configurations, as incorrect changes can make your system unbootable. With proper understanding and careful implementation, efibootmgr becomes a powerful ally in maintaining and optimizing your Linux system’s boot behavior.