---
name: "makefs"
section: "8"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd", "openbsd"]
url: "https://new.carta.tech/makefs"
---

# makefs(8)

create a file system image from a directory tree or a mtree manifest

## NAME

**makefs** – create a file system image from a directory tree or a mtree manifest

## SYNOPSIS

**makefs** \[**-DxZ**\] \[**-B** *endian*\] \[**-b** *free-blocks*\] \[**-d** *debug-mask*\] \[**-F** *mtree-specfile*\] \[**-f** *free-files*\] \[**-M** *minimum-size*\] \[**-m** *maximum-size*\] \[**-N** *userdb-dir*\] \[**-O** *offset*\] \[**-o** *fs-options*\] \[**-R** *roundup-size*\] \[**-S** *sector-size*\] \[**-s** *image-size*\] \[**-T** *timestamp*\] \[**-t** *fs-type*\] *image-file* *directory* \| *manifest* \[*extra-directory* *...*\]

## DESCRIPTION

The utility **makefs** creates a file system image into *image-file* from the directory tree *directory* or from the mtree manifest *manifest*. If any optional directory trees are passed in the *extra-directory* arguments, then the directory tree of each argument will be merged into the *directory* or *manifest* first before creating *image-file*. No special devices or privileges are required to perform this task.

The options are as follows:

- **-B** *endian*

  Set the byte order of the image to *endian*. Valid byte orders are ‘4321’, ‘big’, or ‘be’ for big endian, and ‘1234’, ‘little’, or ‘le’ for little endian. Some file systems may have a fixed byte order; in those cases this argument will be ignored.

- **-b** *free-blocks*

  Ensure that a minimum of *free-blocks* free blocks exist in the image. An optional ‘%’ suffix may be provided to indicate that *free-blocks* indicates a percentage of the calculated image size.

- **-D**

  Treat duplicate paths in an mtree manifest as warnings not error. If this flag is specified more than once, warnings about duplicate paths are not printed at all.

- **-d** *debug-mask*

  Enable various levels of debugging, depending upon which bits are set in *debug-mask*. This option is intended for source debugging. *debug-mask* is a bit map defined in the header file *makefs.h*. See the source for usage, and look for defines starting with *DEBUG\_*.

- **-F** *mtree-specfile*

  *This* *is* *almost* *certainly* *not* *the* *option* *you* *are* *looking* *for.* To create an image from a list of files in an mtree format manifest, specify it as the last argument on the command line, not as the argument to **-F**.

  Use *mtree-specfile* as an [mtree(8)](/mtree/8.md) ‘specfile’ specification. This option has no effect when the image is created from a mtree manifest rather than a directory.

  If a specfile entry exists in the underlying file system, its permissions and modification time will be used unless specifically overridden by the specfile. An error will be raised if the type of entry in the specfile conflicts with that of an existing entry.

  In the opposite case (where a specfile entry does not have an entry in the underlying file system) the following occurs: If the specfile entry is marked **optional**, the specfile entry is ignored. Otherwise, the entry will be created in the image, and it is necessary to specify at least the following parameters in the specfile: **type**, **mode**, **gname**, or **gid**, and **uname** or **uid**, and **link** (in the case of symbolic links). If **time** is not provided, the current time will be used. If **flags** is not provided, the current file flags will be used. Missing regular file entries will be created as zero-length files.

- **-f** *free-files*

  Ensure that a minimum of *free-files* free files (inodes) exist in the image. An optional ‘%’ suffix may be provided to indicate that *free-files* indicates a percentage of the calculated image size.

- **-M** *minimum-size*

  Set the minimum size of the file system image to *minimum-size*.

- **-m** *maximum-size*

  Set the maximum size of the file system image to *maximum-size*. An error will be raised if the target file system needs to be larger than this to accommodate the provided directory tree.

- **-N** *userdb-dir*

  Use the user database text file *master.passwd* and group database text file *group* from *userdb-dir*, rather than using the results from the system's [getpwnam(3)](/getpwnam/3.md) and [getgrnam(3)](/getgrnam/3.md) (and related) library calls.

- **-O** *offset*

  Instead of creating the filesystem at the beginning of the file, start at offset. Valid only for **ffs** and **msdos**.

- **-o** *fs-options*

  Set file system specific options. *fs-options* is a comma separated list of options. Valid file system specific options are detailed below.

- **-p**

  Deprecated. Create a sparse file for **ffs**. This is the same as the preferred **-Z** flag.

- **-R** *roundup-size*

  Round the image up to *roundup-size*. *roundup-size* should be a multiple of the file system block size. This option only applies to the **ffs** file system type.

- **-S** *sector-size*

  Set the file system sector size to *sector-size*. Defaults to 512.

- **-s** *image-size*

  Set the size of the file system image to *image-size*. This is equivalent to setting both the minimum ( **-M**) and the maximum ( **-m**) sizes to the same value. For **ffs** and **msdos** the *image-size* does not include the *offset*. *offset* is not included in that size.

- **-T** *timestamp*

  Specify a timestamp to be set for all filesystem files and directories created so that repeatable builds are possible. The *timestamp* can be a *pathname*, where the timestamps are derived from that file, or an integer value interpreted as the number of seconds from the Epoch. Timestamps in a [mtree(5)](/mtree/5.md) specfile (specified with **-F**) are used even if a default timestamp is specified. However, the timestamps in an mtree manifest are ignored if a default timestamp is specified.

- **-t** *fs-type*

  Create an *fs-type* file system image. The following file system types are supported:

  - **ffs**

    BSD fast file system (default).

  - **cd9660**

    ISO 9660 file system.

  - **msdos**

    FAT12, FAT16, or FAT32 file system.

  - **zfs**

    ZFS pool containing one or more file systems.

- **-x**

  Exclude file system nodes not explicitly listed in the specfile.

- **-Z**

  Create a sparse file for **ffs**. This is useful for virtual machine images.

Where sizes are specified, a decimal number of bytes is expected. Two or more numbers may be separated by an “x” to indicate a product. Each number may have one of the following optional suffixes:

- b

  Block; multiply by 512

- k

  Kibi; multiply by 1024 (1 KiB)

- m

  Mebi; multiply by 1048576 (1 MiB)

- g

  Gibi; multiply by 1073741824 (1 GiB)

- t

  Tebi; multiply by 1099511627776 (1 TiB)

- w

  Word; multiply by the number of bytes in an integer

### FFS-specific options

**ffs** images have ffs-specific optional parameters that may be provided. Each of the options consists of a keyword, an equal sign (‘=’), and a value. The following keywords are supported:

- **avgfilesize**

  Expected average file size.

- **avgfpdir**

  Expected number of files per directory.

- **bsize**

  Block size.

- **density**

  Bytes per inode. If unset, will allocate the minimum number of inodes to represent the filesystem if no free space has been requested (free blocks or minimum size set); otherwise the larger of the newfs defaults or what is required by the free inode parameters if set.

- **fsize**

  Fragment size.

- **label**

  Label name of the image.

- **maxbpg**

  Maximum blocks per file in a cylinder group.

- **minfree**

  Minimum % free.

- **optimization**

  Optimization preference; one of ‘space’ or ‘time’.

- **extent**

  Maximum extent size.

- **maxbpcg**

  Maximum total number of blocks in a cylinder group.

- **version**

  UFS version. 1 for FFS (default), 2 for UFS2.

- **softupdates**

  0 for disable (default), 1 for enable

### CD9660-specific options

**cd9660** images have ISO9660-specific optional parameters that may be provided. The arguments consist of a keyword and, optionally, an equal sign (‘=’), and a value. The following keywords are supported:

- **allow-deep-trees**

  Allow the directory structure to exceed the maximum specified in the spec.

- **allow-illegal-chars**

  Allow illegal characters in filenames. This option is not implemented.

- **allow-lowercase**

  Allow lowercase characters in filenames. This option is not implemented.

- **allow-max-name**

  Allow 37 instead of 33 characters for filenames by omitting the version id.

- **allow-multidot**

  Allow multiple dots in a filename.

- **applicationid**

  Application ID of the image.

- **bootimagedir**

  Boot image directory. This option is not implemented.

- **chrp-boot**

  Write an MBR partition table to the image to allow older CHRP hardware to boot.

- **boot-load-segment**

  Set load segment for the boot image.

- **bootimage**

  Filename of a boot image in the format “sysid;filename”, where “sysid” is one of ‘efi’, ‘i386’, ‘macppc’, or ‘powerpc’.

- **generic-bootimage**

  Load a generic boot image into the first 32K of the cd9660 image.

- **hard-disk-boot**

  Boot image is a hard disk image.

- **isolevel**

  An integer representing the ISO 9660 interchange level where “level” is either ‘1’ or ‘2’. “level” ‘3’ is not implemented.

- **keep-bad-images**

  Do not discard images whose write was aborted due to an error. For debugging purposes.

- **label**

  Label name of the image.

- **no-boot**

  Boot image is not bootable.

- **no-emul-boot**

  Boot image is a “no emulation” ElTorito image.

- **no-trailing-padding**

  Do not pad the image (apparently Linux needs the padding).

- **omit-trailing-period**

  Omit trailing periods in filenames.

- **platformid**

  Set platform ID of section header entry of the boot image.

- **preparer**

  Preparer ID of the image.

- **publisher**

  Publisher ID of the image.

- **rockridge**

  Use RockRidge extensions (for longer filenames, etc.).

- **verbose**

  Turns on verbose output.

- **volumeid**

  Volume set identifier of the image.

### msdos-specific options

**msdos** images have MS-DOS-specific optional parameters that may be provided. The arguments consist of a keyword, an equal sign (‘=’), and a value. The following keywords are supported (see [newfs\_msdos(8)](/newfs_msdos/8.md) for more details):

- **backup\_sector**

  Location of the backup boot sector.

- **block\_size**

  Block size.

- **bootstrap**

  Bootstrap file.

- **bytes\_per\_sector**

  Bytes per sector.

- **create\_size**

  Create file size.

- **directory\_entries**

  Directory entries.

- **drive\_heads**

  Drive heads.

- **fat\_type**

  FAT type (12, 16, or 32).

- **floppy**

  Preset drive parameters for standard format floppy disks (160, 180, 320, 360, 640, 720, 1200, 1232, 1440, or 2880).

- **hidden\_sectors**

  Hidden sectors.

- **info\_sector**

  Location of the info sector.

- **media\_descriptor**

  Media descriptor.

- **num\_FAT**

  Number of FATs.

- **OEM\_string**

  OEM string.

- **offset**

  Offset in device. This option will be ignored if **-O** is set to a positive number.

- **reserved\_sectors**

  Reserved sectors.

- **sectors\_per\_cluster**

  Sectors per cluster.

- **sectors\_per\_fat**

  Sectors per FAT.

- **sectors\_per\_track**

  Sectors per track.

- **size**

  File System size.

- **volume\_id**

  Volume ID.

- **volume\_label**

  Volume Label.

### zfs-specific options

The image created by **makefs** contains a ZFS pool with a single vdev of type ‘disk’. The root dataset is always created implicitly and contains the entire input directory tree unless additional datasets are specified using the options described below.

To keep images reproducible, the pool GUID and other random identifiers will always be the same across runs of **makefs**. This means that when a pool is first imported, its GUID should be reset using [zpool-reguid(8)](/zpool-reguid/8.md) to avoid conflicting with other pools also generated by **makefs**; otherwise, it will not be possible to import other pools. This can be configured from */etc/rc.conf* using the *zpool\_reguid* variable.

The arguments consist of a keyword, an equal sign (‘=’), and a value. The following keywords are supported:

- **ashift**

  The base-2 logarithm of the minimum block size. Typical values are 9 (512B blocks) and 12 (4KB blocks). The default value is 12.

- **autotrim**

  The value of the ‘autotrim’ pool property, either ‘on’ or ‘off’. The default is ‘off’.

- **bootfs**

  The name of the bootable dataset for the pool. Specifying this option causes the ‘bootfs’ property to be set in the created pool.

- **mssize**

  The size of metaslabs in the created pool. By default, **makefs** allocates large (up to 512MB) metaslabs with the expectation that the image will be auto-expanded upon first use. This option allows the default heuristic to be overridden.

- **path**

  The path to the device for this vdev. The default is */dev/null*.

- **verify-txgs**

  Prompt OpenZFS to verify pool metadata during import. This is disabled by default as it may significantly increase import times.

- **poolguid**

  Use the specified 64-bit integer as the pool GUID. If this option is not specified, the pool GUID will be random but fixed across multiple identical invocations of **makefs**. This option is useful for testing but not required for reproducibility.

- **poolname**

  The name of the ZFS pool. This option must be specified.

- **rootpath**

  An implicit path prefix added to dataset mountpoints. By default it is */\<poolname\>*. For creating bootable pools, the *rootpath* should be set to */*. At least one dataset must have a mountpoint equal to *rootpath*.

- **fs**

  Create an additional dataset. This option may be specified multiple times. The argument value must be of the form *\<dataset\>\[;\<prop1=v1\>\[;\<prop2=v2\>\[;...\]\]\]*, where *dataset* is the name of the dataset and must belong to the pool's namespace. For example, with a pool name of ‘test’ all dataset names must be prefixed by ‘test/’. A dataset must exist at each level of the pool's namespace. For example, to create ‘test/foo/bar’, ‘test/foo’ must be created as well.

  The dataset mountpoints determine how the datasets are populated with files from the staged directory tree. Conceptually, all datasets are mounted before any are populated with files. The root of the staged directory tree is mapped to *rootpath*.

  Dataset properties, as described in [zfsprops(7)](/zfsprops/7.md), may be specified following the dataset name. The following properties may be set for a dataset:

  - **atime**

    - **canmount**

    - **compression**

    - **exec**

    - **mountpoint**

    - **setuid**

    Note that **makefs** does not implement compression of files included in the image, regardless of the value of the compression property.

## SEE ALSO

[mtree(5)](/mtree/5.md), [rc.conf(5)](/rc.conf/5.md), [zfsconcepts(7)](/zfsconcepts/7.md), [zfsprops(7)](/zfsprops/7.md), [zpoolprops(7)](/zpoolprops/7.md), [mtree(8)](/mtree/8.md), [newfs(8)](/newfs/8.md), [zpool-reguid(8)](/zpool-reguid/8.md)

## HISTORY

The **makefs** utility appeared in NetBSD 1.6. It was ported to FreeBSD and first appeared in FreeBSD 8.0.

## AUTHORS

Luke Mewburn ⟨*lukem@NetBSD.org*⟩ (original program), Daniel Watt, Walter Deignan, Ryan Gabrys, Alan Perez-Rathke, Ram Vedam (cd9660 support), Christos Zoulas (msdos support), Mark Johnston (zfs support).