grub-syslinux2cfg

grub-syslinux2cfg [OPTION...] [FILE...]

-h, --help
    display this help message and exit

-V, --version
    print version information and exit

-o, --output=FILE
    write output to FILE instead of stdout

FILE
    input Syslinux config file(s); use - for stdin; processes multiple files sequentially

grub-syslinux2cfg is a GRUB2 utility that converts Syslinux, Isolinux, or PXElinux configuration files into equivalent GRUB2 menuentry blocks. It is essential for building hybrid bootable media, such as ISO images or USB drives, that boot with both legacy BIOS Syslinux and GRUB2 (BIOS/UEFI).

The tool parses directives like LABEL, KERNEL, APPEND, INITRD, SPLASH IMAGE, and timeouts, translating them to GRUB syntax including linux, initrd, and gfxterm_background. This enables distributions to generate a single grub.cfg snippet from an existing isolinux.cfg during image creation.

Common in Linux live CD/USB builds (e.g., Ubuntu, Fedora), it outputs to stdout by default or a specified file. Multiple input files produce concatenated menuentries. It assumes standard paths but handles relative image locations.

Does not support all Syslinux features (e.g., complex submenus, COM32 modules, or non-standard includes). Verify generated grub.cfg manually. Images/kernels referenced must be accessible from GRUB root.

grub-syslinux2cfg -o grub.cfg isolinux/isolinux.cfg
Converts isolinux.cfg to grub.cfg for hybrid ISO.

cat isolinux.cfg | grub-syslinux2cfg
Process from stdin.

Introduced in GRUB 2.02 (2012) for hybrid ISO support; improved in GRUB 2.04+ with better APPEND and splash handling. Widely used in distro build tools like live-build and xorriso.

grub-mkconfig(8), syslinux(1), isolinux(1), grub.cfg(5)