--- name: "udfinfo" section: "1" platform: "linux" package: "udftools" version: "2.3-3" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/udfinfo" --- # udfinfo(1) show information about UDF filesystem ## NAME udfinfo — show information about UDF filesystem ## SYNOPSIS **udfinfo \[ options \]** *device* ## DESCRIPTION **udfinfo** shows various information about a UDF filesystem stored either on the block device or in the disk file image. The output from the **udfinfo** is suitable for parsing by external applications or scripts. ## OPTIONS - **-h,--help** Display the usage and the list of options. - **-b,--blocksize=** *block-size* Specify the size of blocks in bytes. Valid block size for a UDF filesystem is a power of two in the range from *512* to *32768* and must match a device logical (sector) size. If omitted, **udfinfo** tries to autodetect block size. First it tries logical (sector) size and then all valid block sizes. - **--startblock=** *start-block* Specify the block location where the UDF filesystem starts. It is used for calculating the block location of the Volume Recognition Sequence (32 kB after the start block) and the first Anchor Volume Descriptor Pointer (256 blocks after the start block). Normally start block is *0*, but for Multisession UDF optical discs it is the block location where the last session of Multisession UDF disc starts. If omitted, **udfinfo** for optical disc tries to detect start block of the last session from disc Table Of Contents. Otherwise value *0* is used. For accessing some previous session of Multisession UDF optical disc, it is required to specify correct block where that previous session starts. And also to specify where that session ends via **--lastblock** option. For Multisession UDF disc images stored in file there is no way to detect where the last session starts and therefore it is necessary to specify the correct start block location manually from the original optical disc Table Of Contents. (Option available since udfinfo 2.3) - **--lastblock=** *last-block* Specify the block location where the UDF filesystem ends. It is used for calculating the block location of second and third Anchor Volume Descriptor Pointer (256 blocks prior the last block and the last block itself). Normally last block is *number of disk blocks minus one*, but for Multisession UDF optical discs when reading different session than the last one (specified by **--startblock**) it is the block location where the specified session ends. If omitted, **udfinfo** for optical disc tried to detect the last recorded block with fallback to the last block of device or disk file image. For accessing some previous session of Multisession UDF optical disc, it is required to specify correct value for both **--startblock** and **--lastblock** options. (Option available since udfinfo 2.3) - **--vatblock=** *vat-block* Specify the block location of the Virtual Allocation Table. Virtual Allocation Table is present only on UDF disks with Virtual Partition Map and must be at the last written/recorded disk block. If omitted, **udfinfo** for optical disc tries to detect the last recorded block with fallback to the last block of block device or disk file image or block specified by **--lastblock**. In most cases, this fallback does not have to work and for disk file images with Virtual Allocation Table it is necessary to specify the correct location. Virtual Allocation Table contains locations of UDF disk blocks needed to read data storage, determinate used and free space blocks, read File Set Identifier and calculate Windows-specific Volume Serial Number. Also, it contains Logical Volume Identifier and overwrite previously stored in Logical Volume Descriptor. - **--locale** Encode UDF string identifiers on output according to current locale settings (default). - **--u8** Encode UDF string identifiers on output to 8-bit OSTA Compressed Unicode format without leading Compression ID byte, which is equivalent to Latin1 (ISO-8859-1) encoding. This will work only for strings which all Unicode code points are below U+100. - **--u16** Encode UDF string identifiers on output to 16-bit OSTA Compressed Unicode format without leading Compression ID byte, which is equivalent to UTF-16BE. - **--utf8** Encode UDF string identifiers on output to UTF-8. ## EXIT STATUS **udfinfo** returns 0 if successful, non-zero if there are problems like a block device does not contain UDF filesystem. ## OUTPUT FORMAT First part of the **udfinfo** standard output contains information in *key*=*value* format. List of all keys with their meaning are in the following table: - *filename* File name of the selected block device or disk file image - *label* label is an alias for *lvid*, see [**udflabel**(8)](/udflabel/8.md) section **UDF LABEL AND UUID** - *uuid* UUID are first 16 hexadecimal lowercase digits of *fullvsid*, but see [**udflabel**(8)](/udflabel/8.md) section **UDF LABEL AND UUID** - *lvid* UDF Logical Volume Identifier stored in UDF Logical Volume Descriptor - *vid* UDF Volume Identifier stored in UDF Primary Volume Descriptor - *vsid* *fullvsid* after *uuid* part, typically 17.–127. character - *fsid* UDF File Set Identifier stored in UDF File Set Descriptor - *fullvsid* UDF Volume Set Identifier stored in UDF Primary Volume Descriptor - *owner* UDF Logical Volume Info1 stored in UDF Implementation Use Volume Descriptor, represents Owner name, person creating the medium or filesystem (available since udfinfo 2.3) - *organization* UDF Logical Volume Info2 stored in UDF Implementation Use Volume Descriptor, represents Organization name responsible for creating the medium or filesystem (available since udfinfo 2.3) - *contact* UDF Logical Volume Info3 stored in UDF Implementation Use Volume Descriptor, represents Contact information for the medium or filesystem (available since udfinfo 2.3) - *appid* UDF Application Identifier stored in UDF Primary Volume Descriptor, identifies application that created medium or filesystem (available since udfinfo 2.3) - *impid* UDF Developer Identifier stored in UDF Implementation Identifier of UDF Primary Volume Descriptor, uniquely identifies the implementation which created medium or filesystem (available since udfinfo 2.3) - *winserialnum* Windows-specific Volume Serial Number - *blocksize* UDF block size - *blocks* Number of all blocks on the selected block device or disk file image - *usedblocks* Number of used space blocks on UDF disk for data storage - *freeblocks* Number of free space blocks on UDF disk for data storage - *behindblocks* Number of blocks which are behind the last block used by UDF disk - *numfiles* Number of stored files on UDF disk - *numdirs* Number of stored directories on UDF disk - *udfrev* UDF revision needed for reading UDF disk - *udfwriterev* UDF revision needed for writing or modifying UDF disk - *startblock* Block location where the UDF filesystem starts (visible only when non-zero, available since udfinfo 2.3) - *lastblock* Block location where the UDF filesystem ends (visible only when it is not same as the last block on disk, available since udfinfo 2.3) - *vatblock* Block location of the UDF Virtual Allocation Table (visible only when available) - *integrity* UDF integrity of Logical Volume, one of: *opened*, *closed*, *unknown* - *accesstype* UDF Access Type, one of: *overwritable*, *rewritable*, *writeonce*, *readonly*, *pseudo-overwritable*, *unknown* - *softwriteprotect* Status of UDF SoftWriteProtect flag, either *yes* or *no* (available since udfinfo 2.2) - *hardwriteprotect* Status of UDF HardWriteProtect flag, either *yes* or *no* (available since udfinfo 2.2) When UDF integrity is not *closed* it means that the UDF disk was not properly unmounted, is in an inconsistent state and needs repairing. When either *softwriteprotect* or *hardwriteprotect* flag is set then UDF disk should be treated as read-only. All UDF string identifiers are stored on UDF disk in Unicode, therefore they are locale or code page agnostic. Options **--locale**, **--u8**, **--u16** and **--utf8** controls how are identifiers encoded on output. All newline characters from the UDF string identifiers are removed, so it is guaranteed that the newline character is present only as a separator. Second part of the **udfinfo** standard output contains list of UDF block types stored on device, one per line in the following format: start=*block-num*, blocks=*block-count*, type=*block-type* With meaning that *block-type* starts at UDF block *block-num* and span *block-count* blocks on device. Windows-specific *Volume Serial Number* is a non-standard 32-bit checksum, calculated as four separate 8-bit XOR checksums of 512 bytes long UDF File Set Descriptor. Therefore, it cannot be set or changed as opposed to UUID which is 64-bit long. This non-standard checksum is used only by Windows systems (since Windows 98 era when it was introduced) and can be displayed on Windows systems by applications like **vol**, **dir** or **fsutil.exe**. ## LIMITATIONS **udfinfo** prior to version 2.3 was unable to handle Multisession UDF discs correctly. It always printed only information about the first session (the oldest one) and not about the last session (the most recent). **udfinfo** prior to version 2.2 was unable to print Unicode strings with code points above U+FFFF correctly. **udfinfo** prior to version 2.2 was unable to read Metadata Partition. Therefore, determining used and free space blocks, reading File Set Identifier and calculating Windows-specific Volume Serial Number did not have to be available or correctly calculated for disks with UDF revisions higher than 2.01 which had Metadata Partition. **udfinfo** prior to version 2.1 was unable to read Virtual Allocation Table stored outside of Information Control Block. Therefore above limitation applied also for some Write Once media. ## AUTHOR ``` Pali Rohár ``` ## AVAILABILITY **udfinfo** is part of the udftools package since version 2.0 and is available from https://github.com/pali/udftools/. ## SEE ALSO [**mkudffs**(8)](/mkudffs/8.md), [**pktsetup**(8)](/pktsetup/8.md), [**udflabel**(8)](/udflabel/8.md), [**cdrwtool**(1)](/cdrwtool/1.md), [**wrudf**(1)](/wrudf/1.md)