---
name: "fsck_msdos"
section: "8"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd", "macos"]
url: "https://new.carta.tech/fsck_msdos"
---

# fsck\_msdos(8)

DOS/Windows (FAT) file system consistency checker

## NAME

**fsck\_msdos** – DOS/Windows (FAT) file system consistency checker

## SYNOPSIS

**fsck\_msdos** \[**-fnpy**\] *filesystem*

## DESCRIPTION

The **fsck\_msdos** utility verifies and repairs FAT file systems (more commonly known as DOS file systems). It checks the specified filesystem and tries to repair all detected inconsistencies, requesting confirmation before making any changes.

If the **-p** flag is given, **fsck\_msdos** preens the specified filesystem. It is normally started this way by [fsck(8)](/fsck/8.md) run from [rc(8)](/rc/8.md) during automatic reboot, when a FAT file system is detected. When preening file systems, **fsck\_msdos** will fix common inconsistencies non-interactively. If more serious problems are found, **fsck\_msdos** does not try to fix them, indicates that it was not successful, and exits.

The options are as follows:

- **-f**

  This option is ignored by **fsck\_msdos**, and is present only for compatibility with programs that check other file system types for consistency, such as [fsck\_ffs(8)](/fsck_ffs/8.md).

- **-n**

  Assume a “no” response to all questions asked by **fsck\_msdos** except for “CONTINUE?”, which is assumed to be affirmative. The filesystem will not be opened for writing. This is the default for file systems to be checked that are concurrently mounted writable.

- **-p**

  Preen the specified filesystem.

- **-y**

  Causes **fsck\_msdos** to assume “yes” as the answer to all operator questions.

If neither of the **-y** or **-n** options are specified, the user may force **fsck\_msdos** to assume an answer of “yes” to all the remaining questions by replying to a question with a value of “F”.

## SEE ALSO

[fs(5)](/fs/5.md), [fstab(5)](/fstab/5.md), [fsck(8)](/fsck/8.md), [fsck\_ffs(8)](/fsck_ffs/8.md), [mount\_msdos(8)](/mount_msdos/8.md), [newfs\_msdos(8)](/newfs_msdos/8.md), [rc(8)](/rc/8.md)

## BUGS

**fsck\_msdos** is still under construction.