Command Section
MKIMG(1)                FreeBSD General Commands Manual               MKIMG(1)

     mkimg - utility to make disk images

     mkimg [-H heads] [-P blksz] [-S secsz] [-T tracksz] [-b bootcode]
           [-c capacity] [-f format] [-o outfile] [-v] [-y]
           [-s scheme [-p partition ...]]
     mkimg --formats | --schemes | --version

     The mkimg utility creates a disk image from the raw partition contents
     specified with the partition argument(s) and using the partitioning
     scheme specified with the scheme argument.  The disk image is written to
     stdout by default or the file specified with the outfile argument.  The
     image file is a raw disk image by default, but the format of the image
     file can be specified with the format argument.

     The disk image can be made bootable by specifying the scheme-specific
     boot block contents with the bootcode argument and, depending on the
     scheme, with a boot partition.  The contents of such a boot partition is
     provided like any other partition and the mkimg utility does not treat it
     any differently from other partitions.

     Some partitioning schemes need a disk geometry and for those the mkimg
     utility accepts the tracksz and heads arguments, specifying the number of
     sectors per track and the number of heads per cylinder (resp.)

     Both the logical and physical sector size can be specified and for that
     the mkimg utility accepts the secsz and blksz arguments.  The secsz
     argument is used to specify the logical sector size.  This is the sector
     size reported by a disk when queried for its capacity.  Modern disks use
     a larger sector size internally, referred to as block size by the mkimg
     utility and this can be specified by the blksz argument.  The mkimg
     utility will use the (physical) block size to determine the start of
     partitions and to round the size of the disk image.

     The -c option can be used to specify a minimal capacity for the disk
     image.  Use this option without the -s and -p options to create an empty
     disk image with the given (virtual) size.  An empty partition table can
     be written to the disk when specifying a partitioning scheme with the -s
     option, but without specifying any partitions.  When the size required to
     for all the partitions is larger than the given capacity, then the disk
     image will be larger than the capacity given.

     The -v option increases the level of output that the mkimg utility

     The -y option is used for testing purposes only and is not to be used in
     production.  When present, the mkimg utility will generate predictable
     values for Universally Unique Identifiers (UUIDs) and time stamps so that
     consecutive runs of the mkimg utility will create images that are

     A set of long options exist to query about the mkimg utility itself.
     Options in this set should be given by themselves because the mkimg
     utility exits immediately after providing the requested information.  The
     version of the mkimg utility is printed when the --version option is
     given.  The list of supported output formats is printed when the
     --formats option is given and the list of supported partitioning schemes
     is printed when the --schemes option is given.  Both the format and
     scheme lists a space-separated lists for easy handling in scripts.

     For a more descriptive list of supported partitioning schemes or
     supported output format, or for a detailed description of how to specify
     partitions, run the mkimg utility without any arguments.  This will print
     a usage message with all the necessary details.

     The mkimg utility supports a number of output file formats.  A short
     description of these is given below.

   QCOW and QCOW2
     QCOW stands for "QEMU Copy On Write".  It's a sparse file format akin to
     VHD and VMDK and QCOW represents the first version.  QCOW2 represents
     version 2 of the file format.  Version 2 is not backward compatible with
     version 1 and adds support for snapshots among other things.  The QCOW
     file formats are natively supported by QEMU and Xen.  To write QCOW,
     specify -f qcow on the command line.  To write version 2 QCOW, specify -f
     qcow2 on the command line.  The preferred file extension is ".qcow" and
     ".qcow2" for QCOW and QCOW2 (resp.), but ".qcow" is sometimes used for
     version 2 files as well.

   RAW file format
     This file format is a sector by sector representation of an actual disk.
     There is no extra information that describes or relates to the format
     itself. The size of the file is the size of the (virtual) disk.  This
     file format is suitable for being copyied onto a disk with utilities like
     dd.  To write a raw disk file, either omit the -f option, or specify -f
     raw on the command line.  The preferred file extension is one of ".img"
     or ".raw", but there's no real convention for it.

   Dynamic VHD and Fixed VHD
     Microsoft's "Virtual Hard Disk" file formats.  The dynamic format is a
     sparse format akin to QCOW and VMDK.  The fixed format is effectively a
     raw format with a footer appended to the file and as such it's often
     indistinguishable from the raw format.  The fixed file format has been
     added to support Microsoft's Azure platform and due to inconsistencies in
     interpretation of the footer is not compatible with utilities like qemu
     when it is specifically instructed to interpreted the file as a VHD file.
     By default qemu will treat the file as a raw disk file, which mostly
     works fine.  To have mkimg create a dynamic VHD file, specify -f vhd on
     the command line.  To create a fixed VHD file for use by Azure, specify
     -f vhdf on the command line.  The preferred file extension is ".vhd".

     VMware's "Virtual Machine Disk" file format.  It's a sparse file format
     akin to QCOW and VHD and supported by many virtualization solutions.  To
     create a VMDK file, specify -f vmdk on the command line.  The preferred
     file extension is ".vmdk".

     Not all virtualization solutions support all file formats, but often
     those virtualization environments have utilities to convert from one
     format to another.  Note however that conversion may require that the
     virtual disk size is changed to match the constraints of the output
     format and this may invalidate the contents of the disk image.  For
     example, the GUID Partition Table (GPT) scheme has a header in the last
     sector on the disk.  When changing the disk size, the GPT must be changed
     so that the last header is moved accordingly.  This is typically not part
     of the conversion process.  If possible, use an output format
     specifically for the environment in which the file is intended to be

     TMPDIR  Directory to put temporary files in; default is /tmp.

     To create a bootable disk image that is partitioned using the GPT scheme
     and containing a root file system that was previously created using
     makefs(8) and also containing a swap partition, run the mkimg utility as
           % mkimg -s gpt -b /boot/pmbr -p freebsd-boot:=/boot/gptboot -p
           freebsd-ufs:=root-file-system.ufs -p freebsd-swap::1G -o gpt.img

     The command line given above results in a raw image file.  This is
     because no output format was given.  To create a VMDK image for example,
     add the -f vmdk argument to the mkimg utility and name the output file

     A nested partitioning scheme is created by running the mkimg utility
     twice.  The output of the first will be fed as the contents of a
     partition to the second.  This can be done using a temporary file, like
           % mkimg -s bsd -b /boot/boot -p freebsd-ufs:=root-file-system.ufs
           -p freebsd-swap::1G -o /tmp/bsd.img
           % mkimg -s mbr -b /boot/mbr -p freebsd:=/tmp/bsd.img -o mbr-bsd.img

     Alternatively, the mkimg utility can be run in a cascaded fashion,
     whereby the output of the first is fed directly into the second.  To do
     this, run the mkimg utility as follows:
           % mkimg -s mbr -b /boot/mbr -p freebsd:-'mkimg -s bsd -b /boot/boot
           -p freebsd-ufs:=root-file-system.ufs -p freebsd-swap::1G' -o

     To accommodate the need to have partitions named or numbered in a certain
     way, the mkimg utility allows for the specification of empty partitions.
     For example, to create an image that is compatible with partition layouts
     found in /etc/disktab, the 'd' partition often needs to be skipped.  This
     is accomplished by inserting an unused partition after the first 2
     partition specifications.  It is worth noting at this time that the BSD
     scheme will automatically skip the 'c' partition by virtue of it
     referring to the entire disk.  To create an image that is compatible with
     the qp120at disk, use the mkimg utility as follows:
           % mkimg -s bsd -b /boot/boot -p freebsd-ufs:=root-file-system.ufs
           -p freebsd-swap::20M -p- -p- -p- -p- -p
           freebsd-ufs:=usr-file-system.ufs -o bsd.img

     For partitioning schemes that feature partition labels, the mkimg utility
     supports assigning labels to the partitions specified.  In the following
     example the file system partition is labeled as 'backup':
           % mkimg -s gpt -p freebsd-ufs/backup:=file-system.ufs -o gpt.img

     dd(1), gpart(8), makefs(8), mdconfig(8), newfs(8)

     The mkimg utility first appeared in FreeBSD 10.1.

     The mkimg utility and manpage were written by Marcel Moolenaar
     <[email protected]>.

FreeBSD 11.1-RELEASE-p4         August 7, 2015         FreeBSD 11.1-RELEASE-p4
Command Section