fsck_udf —
Universal Disk Format file system consistency checker
  
    | fsck_udf | -p[-fH]
      file system ... | 
  
    | fsck_udf | [ -fHnSsy] file system
      ... | 
The fsck_udf utility verifies and repairs Universal Disk
  Format file systems (more commonly known as UDF file systems).
The first form of fsck_udf preens the
    specified file systems. It is normally started by
    fsck(8) run from
    /etc/rc during automatic reboot, when an UDF file
    system is detected. When preening file systems,
    fsck_udf will fix common inconsistencies
    non-interactively. If more serious problems are found,
    fsck_udf does not try to fix them, indicates that it
    was not successful, and exits.
The second form of fsck_udf checks the
    specified file systems and tries to repair all detected inconsistencies,
    requesting confirmation before making any changes.
The options are as follows:
  - -f
- Force detailed checking even when file system is marked closed.
- -H
- Enables heuristic repair options repairing known corruptions in the wild
      caused by bugs.
- -n
- Causes fsck_udfto assume no as the answer to all
      operator questions.
- -p
- Preen the specified file systems.
- -S
- Causes fsck_udfto scan for older VAT tables on
      recordable media. This allows older snapshots of the file system on
      recordable media to be recovered.
- -ssession
- Select session session to be checked on recordable
      media. This allows older sessions of the file system on recordable media
      to be recovered.
- -y
- Causes fsck_udfto assume yes as the answer to all
      operator questions.
Afsck_udf utility appeared in NetBSD
  10.0.
fsck_udf is still under construction. Not all possible
  reparations are implemented.