1.\" $NetBSD: fsck_msdos.8,v 1.9 1997/10/17 11:19:58 ws Exp $ 2.\" 3.\" Copyright (C) 1995 Wolfgang Solfrank 4.\" Copyright (c) 1995 Martin Husemann 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.Dd December 18, 2024 27.Dt FSCK_MSDOSFS 8 28.Os 29.Sh NAME 30.Nm fsck_msdosfs 31.Nd DOS/Windows (FAT) file system consistency checker 32.Sh SYNOPSIS 33.Nm 34.Fl p 35.Op Fl BCf 36.Ar filesystem ... 37.Nm 38.Op Fl BCMny 39.Ar filesystem ... 40.Sh DESCRIPTION 41The 42.Nm 43utility verifies and repairs 44.Tn FAT 45file systems (more commonly known 46as 47.Tn DOS 48file systems). 49.Pp 50The first form of 51.Nm 52preens the specified file systems. 53It is normally started by 54.Xr fsck 8 55run from 56.Pa /etc/rc 57during automatic reboot, when a FAT file system is detected. 58When preening file systems, 59.Nm 60will fix common inconsistencies non-interactively. 61If more serious problems are found, 62.Nm 63does not try to fix them, indicates that it was not 64successful, and exits. 65.Pp 66The second form of 67.Nm 68checks the specified file systems and tries to repair all 69detected inconsistencies, requesting confirmation before 70making any changes. 71.Pp 72The options are as follows: 73.Bl -tag -width indent 74.It Fl B 75Ignored for 76.Xr fsck 8 77compatibility. 78.It Fl C 79Ignored for 80.Xr fsck 8 81compatibility. 82.It Fl F 83Compatibility with the wrapper 84.Xr fsck 8 85which seeks to determine whether the file system needs to be cleaned 86immediately in foreground, or if its cleaning can be deferred to background. 87FAT (MS-DOS) file systems must always be cleaned in the foreground. 88A non-zero exit code is always returned for this option. 89.It Fl M 90Causes 91.Nm 92to not use 93.Xr mmap 2 94when checking a FAT32 file system. 95This option is mainly for debugging purposes and is not normally necessary. 96The 97.Nm 98utility will automatically fall back to use a simple LRU cache of 4 MiB 99when it failed to perform 100.Xr mmap 2 , 101or when 102.Fl M 103is specified. 104.It Fl f 105Force 106.Nm 107to check 108.Dq clean 109file systems when preening. 110.It Fl n 111Causes 112.Nm 113to assume 114.Dq Li no 115as the answer to all operator 116questions, except 117.Dq Li CONTINUE? . 118.It Fl p 119Preen the specified file systems. 120.It Fl y 121Causes 122.Nm 123to assume 124.Dq Li yes 125as the answer to all operator questions. 126.El 127.Sh SEE ALSO 128.Xr fsck 8 , 129.Xr fsck_ffs 8 , 130.Xr mount_msdosfs 8 131.Sh HISTORY 132The 133.Nm 134utility appeared in 135.Nx 1.2 . 136.Nm 137first appeared in 138.Fx 4.4 . 139.Sh BUGS 140The 141.Nm 142utility is 143.Ud 144