Linux efivar Guide

Linux efivar Guide

Complete beginner-friendly guide to efivar on Linux, covering Arch Linux, CachyOS, and other distributions including EFI variable management, UEFI variable access, and firmware variable control.

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Table of Contents

1. efivar Installation
2. efivar Basics
3. Reading Variables
4. Writing Variables
5. Troubleshooting

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efivar Installation

Install efivar

Arch/CachyOS:

# Install efivar
sudo pacman -S efivar

Debian/Ubuntu:

sudo apt install efivar

Fedora:

sudo dnf install efivar

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efivar Basics

List Variables

Basic usage:

# List EFI variables
efivar -l

# Shows all EFI variables

Read Variable

Read value:

# Read variable
efivar -n 8be4df61-93ca-11d2-aa0d-00e098032b8c-BootOrder

# -n = name (variable name)

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Reading Variables

Variable Information

Get info:

# Variable information
efivar -p -n VariableName

# -p = print (shows variable)

GUID Format

Variable format:

# Variables use GUID format
# Format: GUID-VariableName
efivar -n GUID-VariableName

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Writing Variables

Set Variable

Write variable:

# Write variable (advanced, use with caution)
sudo efivar -w -n GUID-VariableName -t type -a attributes -d data

# -w = write
# -t = type
# -a = attributes
# -d = data

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Troubleshooting

efivar Not Found

Check installation:

# Check efivar
which efivar

# Install if missing
sudo pacman -S efivar

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Summary

This guide covered efivar usage, EFI variable management, and UEFI variable access for Arch Linux, CachyOS, and other distributions.

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Next Steps

• UEFI and Secure Boot - UEFI guide
• efibootmgr Guide - Boot entry management
• efivar Documentation: man efivar

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This guide covers Arch Linux, CachyOS, and other Linux distributions. For distribution-specific details, refer to your distribution's documentation.