.\"	$NetBSD: fsck_msdos.8,v 1.9 1997/10/17 11:19:58 ws Exp $
.\"
.\" Copyright (C) 1995 Wolfgang Solfrank
.\" Copyright (c) 1995 Martin Husemann
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\" $FreeBSD$
.\"
.Dd January 6, 2020
.Dt FSCK_MSDOSFS 8
.Os
.Sh NAME
.Nm fsck_msdosfs
.Nd DOS/Windows (FAT) file system consistency checker
.Sh SYNOPSIS
.Nm
.Fl p
.Op Fl Cf
.Ar filesystem ...
.Nm
.Op Fl CMny
.Ar filesystem ...
.Sh DESCRIPTION
The
.Nm
utility verifies and repairs
.Tn FAT
file systems (more commonly known
as
.Tn DOS
file systems).
.Pp
The first form of
.Nm
preens the specified file systems.
It is normally started by
.Xr fsck 8
run from
.Pa /etc/rc
during automatic reboot, when a FAT file system is detected.
When preening file systems,
.Nm
will fix common inconsistencies non-interactively.
If more serious problems are found,
.Nm
does not try to fix them, indicates that it was not
successful, and exits.
.Pp
The second form of
.Nm
checks the specified file systems and tries to repair all
detected inconsistencies, requesting confirmation before
making any changes.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl C
Compatibility with the corresponding
.Xr fsck 8
option (skip check if clean), defined to no-op.
.It Fl F
Compatibility with the wrapper
.Xr fsck 8
which seeks to determine whether the file system needs to be cleaned
immediately in foreground, or if its cleaning can be deferred to background.
FAT (MS-DOS) file systems must always be cleaned in the foreground.
A non-zero exit code is always returned for this option.
.It Fl M
Causes
.Nm
to not use
.Xr mmap 2
when checking a FAT32 file system.
This option is mainly for debugging purposes and is not normally necessary.
The
.Nm
utility will automatically fall back to use a simple LRU cache of 4 MiB
when it failed to perform
.Xr mmap 2 ,
or when
.Fl M
is specified.
.It Fl f
Force
.Nm
to check
.Dq clean
file systems when preening.
.It Fl n
Causes
.Nm
to assume
.Dq Li no
as the answer to all operator
questions, except
.Dq Li CONTINUE? .
.It Fl p
Preen the specified file systems.
.It Fl y
Causes
.Nm
to assume
.Dq Li yes
as the answer to all operator questions.
.El
.Sh SEE ALSO
.Xr fsck 8 ,
.Xr fsck_ffs 8 ,
.Xr mount_msdosfs 8
.Sh HISTORY
The
.Nm
utility appeared in
.Nx 1.2 .
.Nm
first appeared in
.Fx 4.4 .
.Sh BUGS
The
.Nm
utility is
.Ud