---
name: "mksuncd"
section: "1"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd"]
url: "https://new.carta.tech/mksuncd"
---

# mksuncd(1)

add a bootable UFS partition to a filesystem image

## NAME

**mksuncd** – add a bootable UFS partition to a filesystem image

## SYNOPSIS

**mksuncd** *partition-letter* *isofile* *ufsfile*

## DESCRIPTION

The **mksuncd** utility adds the file *ufsfile* to the end of *isofile*. *ufsfile* is assumed to be a bootable filesystem image and *isofile* is assumed to be something like an ISO 9660 filesystem. A Sun-style disklabel is expected to already be present at the beginning of *isofile*, and **mksuncd** will update that label so that the partition (a-h) given by *partition-letter* points to *ufsfile* within *isofile*.

Based on the label in *isofile*, that file is padded so that added files are always on cylinder boundaries. This is a requirement of the PROM.

## BUGS

This program is not endian or type safe. It makes several assumptions about both based on its SPARC bias.