froggmaster / efirename

A Bash script to rename EFI boot records

EFIRename

A bash script designed to simplify renaming EFI boot entries.

Background

EFI / UEFI, boot configurations

EFI / UEFI is a specification that defines a software interface between an operating system and platform firmware. It is intended by hardware manufacturers to replace the legacy BIOS firmware interface.

In particular this specification allows to define OS boot configurations to be loaded / executed upon system power on. These boot configurations specify disk partitions to boot from and are typically identified by their text labels that are listed in the "Startup" / "Boot" EFI setup section. These boot configurations may be optionally selectable upon system startup.

The problem

Operating system installation routines tend to have these boot configuration labels hard-coded and to create them in EFI PROM automatically. So in case a computer has, say, several Ubuntu instances installed, it is also likely to have several identical "ubuntu" boot configuration labels in its EFI menus, causing a kind of confusion.

One might further want to rename boot configurations, so to make them distinguishable, but unfortunately the standard efibootmgr utility has no option for that. It is only possible to delete a boot configuration entry and re-create it with a new label. Meanwhile, the data that is necessary for re-creating a boot configuration entry is not trivial and requires certain inquiries into EFI configuration and disk partition attributes.

The script

The rename-efi-entry script is designed to facilitate renaming EFI boot configuration entries using efibootmgr utility for entry deleting and re-creation. It automates querying current EFI configuration and bootable partition data, and also shaping command line arguments for efibootmgr.

Usage

sudo ./rename-efi-entry.bash existing_efi_label new_efi_label [bootnum]

Table 1. Command line arguments

existing_efi_label	existing EFI entry label to be renamed
new_efi_label	the new label value to be assigned
bootnum	optional: the bootnum value of the EFI entry to be renamed, required in case of repeating label values to avoid ambiguity

E.g.:

sudo ./rename-efi-entry ubuntu 'ubuntu 18.04'

or in case of multiple boot entries labeled as 'ubuntu':

sudo ./rename-efi-entry ubuntu 'ubuntu 18.04' 0001

In case of doubt bootnum values may be clarified using efibootmgr --verbose command, see the first column:

$ efibootmgr --verbose
BootCurrent: 0001
Timeout: 0 seconds
BootOrder: 0002,0001,0017,001B,0000,0016,0019,001A,0018
Boot0000  Windows Boot Manager	HD(1,MBR,0x5092863d,0x3cde8c,0x1340)/File(\EFI\Microsoft\Boot\bootmgfw.efi)WINDOWS...
Boot0001* ubuntu            	HD(1,GPT,2ffcc127-f6ce-40f0-9932-d1dfd14e9462,0x800,0x100000)/File(\EFI\ubuntu\shimx64.efi)
Boot0002* ubuntu            	HD(1,GPT,cba13b09-d754-4d31-9719-369fa60928d1,0x800,0x100000)/File(\EFI\ubuntu\shimx64.efi)
Boot0010  ...

Required bootnum values (e.g. 0001 from Boot0001) may be further identified by checking corresponding uuid values (e.g. 2ffcc127-f6ce-40f0-9932-d1dfd14e9462) against values provided by sfdisk -d command, e.g.:

$ sudo sfdisk -d /dev/sda
label: gpt
label-id: 0560DAA2-3010-47A2-B083-047C813F0A04
device: /dev/sda
unit: sectors
first-lba: 34
last-lba: 1953525134

/dev/sda1 : start=        2048, size=     1048576, type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, uuid=2FFCC127-F6CE-40F0-9932-D1DFD14E9462, name="EFI System Partition"
/dev/sda2 : start=     1050624, size=   102400000, type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=A06790C2-3818-4F57-84EF-4D1B9FFB417E, name="SSD system"
/dev/sda3 : start=   103450624, size=  1850073088, type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, uuid=67A374C2-081E-477E-945C-78BE129A2044, name="SSD data"

Implementation details

What the script does under the hood, is:

• obtain a list of disk devices using lsblk;

• obtain a list of disk partitions and their uuid values for every disk device using sfdisk;

• obtain a list of EFI boot entries using efibootmgr;

• filter EFI boot entries against existing_efi_label value, supplied by the user as command line argument;

• make sure that this boot entry identification is unique, using bootnum if necessary;

• extract uuid value from the EFI boot entry to be renamed, and use it to identify the relevant disk partition and its device name;

• verify matching of partition numbers between EFI boot entry and partition device name;

• shape the commands for efibootmgr to delete the existing EFI boot entry and to create a new one with required label;

• ask final user consent;

• apply the efibootmgr commands.

Limitations

This script was designed to rename Linux EFI boot entries but it does work on Windows EFI entries as well. Please note however that only Windows 10 EFI entries have been tested.

Important usage notes

Use at your own risk, you can damage your EFI boot entries. It may be wise to review the efibootmgr commands before final execution…​

Licenses

The project is issued and distributed under the following licenses:

• The BSD 2-Clause License - for those who may care about legal issues seriously :)

• The License in Three Lines (LITL) - for those who may like it :)
  More on LITL:

  • Original of 2010

    • https://github.com/license-in-three-lines?tab=repositories

  • Revival of 2013

    • https://litl-license.org/

    • https://github.com/litl-license/litl-license