mkudffs [ options ] device [ blocks-count ]
mkudffs is used to create a UDF filesystem on a device (usually a disk). device is the special file corresponding to the device (e.g. /dev/hdX) or file image. blocks-count is the number of blocks on the device. If omitted, mkudffs automagically figures the filesystem size. The order of options matters. Encoding option must be first and options to override default settings implied by the media type or UDF revision should be after the option they are overriding.
Display the usage and list of options.
- -l,--label= label
Specify the UDF label. UDF label is synonym for specifying both --lvid and --vid options. If omitted, mkudffs label is LinuxUDF. (Option available since mkudffs 1.1)
- -u,--uuid= uuid
Specify the UDF uuid. It must be exactly 16 hexadecimal lowercase digits and is used for first 16 characters of --fullvsid option. If omitted, mkudffs uuid is generated from local time and a random number. (Option available since mkudffs 1.1)
- -b,--blocksize= block-size
Specify the size of blocks in bytes. Valid block size for a UDF filesystem is power of two in range from 512 to 32768 and must match a device logical (sector) size. If omitted, mkudffs block size is set to device logical block (sector) size. If logical block (sector) size is unknown (e.g. when creating disk image) then for --media-type=hd is used block size 512 and for other media types 2048. (Prior to mkudffs 1.1 default value was always 2048 independently of --media-type)
- -m,--media-type= media-type
Specify the media type. Must be specified before --udfrev. Default value is autodetected. When autodetection does not work (e.g. when creating disk image) then hd value is assumed. Valid media types are:
HD (Hard Disk)
WORM (Write Once Read Many)
MO (Magneto Optical)
CD-ROM (CD Read-Only Memory)
CD-R (CD Recordable)
CD-RW (CD Read-Write)
DVD-ROM (DVD Read-Only Memory)
DVD-R (DVD Recordable)
DVD-RW (DVD Read-Write)
DVD-RAM (DVD Random Access Memory)
BD-R (Blu-ray Disc Recordable)
(Short option variant -m and values cd, dvdr, bdr are available since mkudffs 2.0 and autodetection is supported since mkudffs 2.2)
- -r,--udfrev= udf-revision
Specify the UDF revision to use, either in hexadecimal BCD (e.g. 0x0201) or decimal (e.g. 2.01) format. Valid revisions are 1.01, 1.02, 1.50, 2.00, 2.01, 2.50 and 2.60. If omitted, mkudffs UDF revision is 2.01, except for Blu-ray Discs which is 2.50. UDF revisions higher then 2.01 are experimental. Option must be specified after --media-type. (Values in decimal format and UDF revisions higher then 2.01 are supported since mkudffs 2.0, UDF revision 1.01 is supported since mkudffs 2.1)
Not really, do not write to device. Just simulate and display what would happen with device. Useful for determining the calculated location of different UDF blocks. (Option available since mkudffs 2.0)
Create a new image file specified by device with blocks-count and fail if file already exists. If omitted, mkudffs creates a new image file only in case it does not exist yet. (Option available since mkudffs 2.0)
- --lvid= logical-volume-identifier
Specify the Logical Volume Identifier. If omitted, mkudffs Logical Volume Identifier is LinuxUDF. Most UDF implementations use this identifier as a disk label.
- --vid= volume-identifier
Specify the Volume Identifier. If omitted, mkudffs Volume Identifier is LinuxUDF.
- --vsid= volume-set-identifier
Specify the 17.–127. character of Volume Set Identifier. If omitted, mkudffs Volume Set Identifier is LinuxUDF.
- --fsid= file-set-identifier
Specify the File Set Identifier. If omitted, mkudffs File Set Identifier is LinuxUDF.
- --fullvsid= full-volume-set-identifier
Specify the full Volume Set Identifier. Overwrite previous --uuid and --vsid options. (Option available since mkudffs 1.1)
- --owner= owner-name
Specify the Owner name, person creating the medium or filesystem. It is stored in UDF Logical Volume Info1, part of UDF Implementation Use Volume Descriptor. (Option available since mkudffs 2.3)
- --organization= organization-name
Specify the Organization name responsible for creating the medium or filesystem. It is stored in UDF Logical Volume Info2, part of UDF Implementation Use Volume Descriptor. (Option available since mkudffs 2.3)
- --contact= contact-information
Specify the Contact information for the medium or filesystem. It is stored in UDF Logical Volume Info3, part of UDF Implementation Use Volume Descriptor. (Option available since mkudffs 2.3)
- --uid= uid
Specify the uid of the root (/) directory. If omitted, mkudffs uid is 0. Special value -1 means invalid or not specified uid. (Option available since mkudffs 1.1)
- --gid= gid
Specify the gid of the root (/) directory. If omitted, mkudffs gid is 0. Special value -1 means invalid or not specified gid. (Option available since mkudffs 1.1)
- --mode= mode
Specify permissions in octal mode bits of the root (/) directory. If omitted, mkudffs mode is 0755. (Option available since mkudffs 2.0)
This option specify that the whole UDF disk should be treated as read-only. It sets SoftWriteProtect domain flag in Logical Volume Descriptor and in File Set Descriptor. Plus for overwritable media types (hd, dvdram, dvdrw) set UDF Access Type to read-only. (Option available since mkudffs 2.2)
- --bootarea= fill
Specify how to fill UDF boot area which is the first 32kB of the disk and is not used by UDF itself. Option mbr make sense only when running mkudffs on whole disk, not on just one partition. Valid options are:
preserve existing UDF boot area, do not touch it (default for media type different from hd)
erase existing UDF boot area, fill it by zeros (default for hd media type on partitions and on removable disks)
put MBR table with one partition which starts at sector 0 (includes MBR itself) and spans whole disk device, needed only for non-removable hard disks used on Microsoft Windows systems (default for hd media type on non-removable hard disk without partitions), see section Whole Disk VS Partition
same as mbr but explicitly set MBR sector size to sec-size value, default sec-size is device logical block (sector) size with fallback to size 512 bytes
(Option available since mkudffs 2.0)
- --strategy= strategy
Specify the allocation strategy to use. Valid strategies are 4 and 4096. If omitted, mkudffs strategy is based on the --media-type.
- --spartable, --spartable= spartable-number
Enable usage Sparing Table. Optionally specify also the number of sparing tables. Valid numbers are 1–4. When the spartable number is omitted then two tables are written to the disc. If the option is omitted then usage of Sparing Table depends on the media type. (Option prior to mkudffs 2.0 was available only for cdrw media type)
- --sparspace= num-of-entires
Specify the number of entries in Sparing Table. If omitted, the default number of entries is 1024, but depends on the media type. (Option available since mkudffs 2.0)
- --packetlen= length
Packet length in a number of blocks used for alignment. All continuous UDF structures would be aligned to packets. It specifies also the size of the Sparing Space and packet length in Sparing Table. It should match the device ECC/packet length. If omitted, default value for DVD discs is 16 blocks, for CD/BD discs it is 32 blocks and otherwise 1 block. (Option prior to mkudffs 2.1 was available only for cdrw and dvdrw media types)
Enable usage of Virtual Allocation Table (VAT). If omitted, usage depends on the media type. (Option available since mkudffs 2.0)
- --startblock= start-block
Specify the block location where the UDF filesystem starts.
Normally start block is 0, but when creating second or higher session for Multisession UDF optical disc it is the block location where that new session starts.
When updating existing Multisession UDF image file, mkudffs overwrites only data blocks for a new session at start block position in the image file.
When creating a new UDF image file, mkudffs stores only data blocks for a new session at beginning of the image file. Therefore data for start block would be written to the zero block instead of the start block. Such image without leading blocks (where are located previous sessions) is suitable for burning a new session to the optical disc. But it cannot be read or detected by any UDF tool until leading zero blocks (or previous sessions) are prepended to the image file.
For calculating position where a new session of particular optical disc should start is required to use software which would be used for burning newly created image. So for example, if for burning is used wodim(1) then second value on output from wodim -msinfo call is start block. Accordingly for cdrecord(1) call cdrecord -msinfo or for cdrdao(1) call cdrdao msinfo or for xorriso(1) call xorriso -as cdrecord dev=/dev/cdrw -msinfo.
(Option available since mkudffs 2.3)
- --minblocks= min-num-of-blocks
Specify minimal number of blocks to write on disc with Virtual Allocation Table.
This option affects block position where is written Virtual Allocation Table. And in case option --closed is used then also it affects block position of the second Anchor Volume Descriptor Pointer.
Default value for cdr media type is 300. This is safe default to allow burning CD-R disc image in Track-at-Once mode. This mode requires to burn image with minimal size of 300 sectors. Burning CD-R discs in other modes (e.g. Disc-at-Once or Packet-Writing) may allow to allow to use also smaller disc images.
For all other media types there is no default minimal limit.
(Option available since mkudffs 2.3)
Close disc with Virtual Allocation Table. AVDP is written also to the end of the disc. By default, the disc with Virtual Allocation Table is not closed.
- --space= space
Specify the Space Set. Unallocated Space Set is used for media which blocks may be allocated immediately. Freed Space Set is used for media which blocks needs to be specially prepared/erased before allocation. In Space Table is stored list of unallocated extents. In Space Bitmap is stored bitmap of unallocated blocks. Not used for VAT.
Unallocated Bitmap (default)
- --ad= ad
Specify the Allocation Descriptors of the root (/) directory.
Allocation Descriptors in ICB (default)
Short Allocation Descriptors
Long Allocation Descriptors
Don't Use Extended File Entries for the root (/) directory. Affects only UDF 2.00 or higher. Must be specified after --udfrev.
Treat identifier string options as strings encoded according to the current locale settings (default). Must be specified as the first argument. (Option available since mkudffs 2.0)
Treat identifier string options as strings encoded in 8-bit OSTA Compressed Unicode format without leading Compression ID byte, which is equivalent to Latin1 (ISO-8859-1). Must be specified as first argument.
Treat identifier string options as strings encoded in 16-bit OSTA Compressed Unicode format without leading Compression ID byte, which is equivalent to UTF-16BE. Note that it is not possible to include zero byte in command line options, therefore any character which has at least one zero byte cannot be supplied (this applies to all Latin1 characters). Must be specified as the first argument.
Treat identifier string options as strings encoded in UTF-8. Must be specified as the first argument. (Prior to mkudffs 2.0 this was default option)
Operating Systems Support
UDF filesystem is natively supported by large amount of operating systems. See following compatibility table:
|Operating system||Maximum UDF revision for|
|Linux||2.3.17 – 2.4.5||2.00||2.00|
|2.4.6 – 2.6.25||2.01||2.01|
|2.6.26 (and new)||2.50||2.01|
|Vista (and new)||2.60||2.50|
|Mac OS||8.1 – 8.5||1.02||none|
|8.6 – 9.2||1.50||1.50|
|Mac OS X||10.0 – 10.3||1.50||1.50|
|10.5 (and new)||2.60||2.50|
|FreeBSD||5 (and new)||1.50||none|
|5.0 (and new)||2.60||2.60|
|OpenBSD||3.8 – 3.9||1.02||none|
|4.0 – 4.6||1.50|
|4.7 (and new)||2.60|
|Solaris||7 (and new)||1.50||1.50|
|AIX||5.2 (and new)||2.01||2.01|
Note that Windows 98 and Windows Me can read UDF filesystem only from CD and DVD optical discs, not from hard disks.
In most cases, operating systems are unable to mount UDF filesystem if UDF block size differs from logical sector size of the device. Typically hard disks have sector size 512 bytes and optical media 2048 bytes. Therefore UDF block size must match the logical sector size of the device.
Linux kernel prior to version 2.6.30 used hardcoded UDF block size of 2048 bytes independently of logical sector size, therefore it was not able to automatically mount UDF filesystem if block size differed from 2048. Since 2.6.30 and prior to 4.11 Linux kernel used a logical sector size of the device as UDF block size, plus it tried fallback to 2048. Since 4.11 it uses logical sector size and fallbacks to any valid block size between logical sector size and 4096. Therefore since version 2.6.30 Linux kernel can automatically mount UDF filesystems correctly if UDF block size matches device logical sector size and since version 4.11 can automatically also mount devices which sector size does not match UDF block size. In any case and also for Linux kernel prior to version 2.6.30, different UDF block size (which is not autodetected) can be manually specified via bs=blocksize mount parameter.
Whole Disk VS Partition
UDF filesystem is supposed to be formatted on the whole media and not to the partitioned hard disk. Mac OS X systems enforce this rule and reject to automatically mount UDF filesystem unless it is formatted on the whole unpartitioned hard disk. Possible partition table (e.g. MBR or GPT) on disk with valid UDF filesystem is ignored. On the other hand, Microsoft Windows systems are unable to detect non-removable hard disks without MBR or GPT partition table. Removable disks do not have this restriction. A consequence is that non-removable hard disks formatted to UDF by Windows Vista+ are not recognized by Mac OS X systems and vice-versa. Note that manual mount of UDF partition on partitioned hard disk on Mac OS X system is possible and working (e.g. by running commands:
mkdir /Volumes/DriveName && mount_udf /dev/disk1s1 /Volumes/DriveName). But there is no known way to mount an unpartitioned non-removable disk on Windows system.
Thanks to reserved and unused UDF boot area (first 32kB of UDF filesystem) it is possible to deal with this problem, by putting MBR on such non-removable hard disk just for compatibility reasons with Windows. Such MBR table would contain one partition which starts at sector 0 (includes MBR itself) and spans whole disk device. So the whole disk device and also the first partition on disk points to same sectors. Therefore UDF filesystem can be mounted either from whole disk device (needed for Mac OS X systems) or from first partition (needed for Microsoft Windows systems).
Linux kernel ignores MBR table if contains partition which starts at sector 0. Normally Linux kernel can detect and mount UDF filesystem either on a partition or on whole disk device. It does not have any restrictions.
mkudffs option --bootarea=mbr put such MBR table for compatibility with Microsoft Windows systems into disk when formatting.
Linux Label Bugs
In most cases Logical Volume Identifier is used as UDF label. But Linux libblkid prior to version 2.26 used Volume Identifier. Therefore mkudffs --label for compatibility reasons set both Logical Volume Identifier and Volume Identifier.
Linux libblkid prior to version 2.30 incorrectly processed non-ASCII identifier strings encoded in 8-bit OSTA Compressed Unicode format. Therefore mkudffs since version 2.0 for compatibility reasons tries to encode a non-ASCII identifier strings in 16-bit OSTA Compressed Unicode format and then fallbacks to 8-bit format.
For more information about UDF Label and UUID see udflabel(8) section UDF LABEL AND UUID.
mkudffs returns 0 if successful, non-zero if there are problems.
mkudffs cannot create UDF 2.50 Metadata partition, therefore it does not support UDF revisions higher than 2.01 for non Write Once media yet. So there is no support for Blu-ray discs which needs UDF 2.50 (except for Blu-ray Disc Recordable which does not require Metadata partition).
mkudffs prior to version 2.2 was unable to process Unicode strings with code points above U+FFFF. When option --utf8 was specified then input strings were limited to 3-byte UTF-8 sequences and when option --u16 was specified then input strings were limited just to UCS-2BE strings (subset of UTF-16BE).
mkudffs prior to version 1.1 was unable to process non-ASCII characters from identifier strings in --utf8 mode, --vsid option was completely broken and --blocksize must have been manually specified for hard disks as default value was hardcoded for optical disks. mkudffs prior to version 2.0 generated broken and unreadable cdr disc images.
Ben Fennema Pali Rohár <email@example.com>
mkudffs is part of the udftools package and is available from https://github.com/pali/udftools/.
pktsetup(8), udflabel(8), cdrwtool(1), udfinfo(1), wrudf(1)
mount(8), udfinfo(1), udflabel(8), wrudf(1).
The man page mkfs.udf(8) is an alias of mkudffs(8).