About

grub2-theme-preview came into life when I was looking around for available GRUB 2.x themes and wanted a way to quickly see a theme in action without rebooting real hardware.

It takes a theme folder (or just a single picture), creates a temporary bootable image using grub2-mkrescue and launches that image in a virtual machine using KVM/QEMU, all without root privileges.

(Showing theme gutsblack-archlinux)

Installation

To install the latest release from PyPI:

# pip install --user grub2-theme-preview

To install from a Git clone for development:

# pip install --user --editable .

Please make sure to install these non-PyPI dependencies as well:

grub-mkrescue of GRUB 2 (package grub-common on Debian and Ubuntu)
QEMU — hypervisor that performs hardware virtualization
OVMF — EFI bios image for use with QEMU
mtools — collection of utilities to access MS-DOS
xorriso of libisoburn — frontend which enables creation and expansion of the ISO format

Usage

# grub2-theme-preview --help
usage: grub2-theme-preview [-h] [--grub-cfg PATH] [--verbose]
                           [--resolution WxH] [--timeout SECONDS]
                           [--add TARGET=/SOURCE] [--version]
                           [--grub2-mkrescue COMMAND] [--qemu COMMAND]
                           [--xorriso COMMAND] [--no-kvm] [--debug]
                           [--plain-rescue-image]
                           PATH

positional arguments:
  PATH                  path of theme directory (or PNG/TGA image file) to
                        preview

optional arguments:
  -h, --help            show this help message and exit
  --grub-cfg PATH       path of custom grub.cfg file to use (default:
                        /boot/grub{2,}/grub.cfg)
  --verbose             increase verbosity
  --resolution WxH      set a custom resolution, e.g. 800x600
  --timeout SECONDS     set GRUB timeout in whole seconds or -1 to disable
                        (default: 30 seconds)
  --add TARGET=/SOURCE  make grub2-mkrescue add file(s) from /SOURCE to
                        /TARGET in the rescue image (can be passed multiple
                        times)
  --version             show program's version number and exit

command location arguments:
  --grub2-mkrescue COMMAND
                        grub2-mkrescue command (default: auto-detect)
  --qemu COMMAND        KVM/QEMU command (default: qemu-system-<machine>)
  --xorriso COMMAND     xorriso command (default: xorriso)

arguments related to invokation of QEMU/KVM:
  --display DISPLAY     pass "-display DISPLAY" to QEMU, see "man qemu" for
                        details (default: use QEMU's default display)
  --full-screen         pass "-full-screen" to QEMU
  --no-kvm              do not pass -enable-kvm to QEMU (and hence fall back
                        to acceleration "tcg" which is significantly slower
                        than KVM)
  --vga CARD            pass "-vga CARD" to QEMU, see "man qemu" for details
                        (default: use QEMU's default VGA card)

debugging arguments:
  --debug               enable debugging output
  --plain-rescue-image  use unprocessed GRUB rescue image with no theme
                        patched in; useful for checking if a plain GRUB rescue
                        image shows up a GRUB shell, successfully.