.\" Copyright (c) 2009-2010 Apple Inc.  All rights reserved.
.\"
.Dd January 19, 2010
.Dt EXFAT.UTIL 8 
.Os Darwin
.Sh NAME
.Nm exfat.util
.Nd ExFAT file system utility
.Sh SYNOPSIS
.Nm
.Fl p Ar device removable writable
.Nm
.Fl k Ar device
.Nm
.Fl s Ar device
.Nm
.Fl m Ar device directory removable writable nosuid nodev
.Nm
.Fl u Ar device
.Sh DESCRIPTION
The
.Nm
command supports the probing of ExFAT file systems, and getting or setting a
volume UUID.
.Pp
Options:
.Bl -tag -width Ds
.It Fl p Ar device removable writable
Probe the
.Ar device
to determine whether it contains an ExFAT file system.  The
.Ar removable
and
.Ar writable
arguments are ignored for compatibility with other file system utilities.
If the device appears to contain an ExFAT file system, the exit status is 255.
If the file system contains a label (volume name), that name is written to
standard output.
If the device does not appear to contain an ExFAT file system, the exit status is 254.
An exit status of 252 indicates that an I/O error occurred.
.It Fl k Ar device
Return the volume UUID of the ExFAT file system on
.Ar device .
If the device appears to contain an ExFAT file system, the volume's UUID is
written to standard output (as formatted by
.Xr uuid_unparse 3 ) ,
and the exit status is 253.
If the root directory contains a Volume GUID entry, that GUID is the value returned;
otherwise, the 32-bit volume serial number stored in the boot sector is converted
to a UUID and returned.
If the device does not appear to contain an ExFAT file system, the exit status is 254.
An exit status of 252 indicates that an I/O error occurred.
.Pp
.Ar device
may be mounted or unmounted.
If it is mounted, the UUID is obtained through the file system using the
.Xr getattrlist 2
call.
If the device is not mounted,
.Nm
reads from the device directly.
.It Fl s Ar device
Set a new UUID for the ExFAT file system on
.Ar device ,
which must not be mounted.  This generates a new UUID using
.Xr uuid_generate 3
and stores that UUID in a Volume GUID entry in the root directory (creating
one if one does not exist, or updating an existing entry).
If the UUID is successfully set, the exit status is 253.
If the device does not appear to contain an ExFAT file system, the exit status is 254.
An exit status of 252 indicates that
.Ar device
was already mounted, or an I/O error occurred.
.It Fl m Ar device directory removable writable nosuid nodev
Deprecated.
Mount the ExFAT file system from
.Ar device
onto
.Ar directory .
The
.Ar removable
argument should be either
.Cm removable
if the device is removable, or
.Cm fixed
otherwise.
The actual argument value is currently ignored.
The
.Ar writable
argument must be either
.Cm readonly
or
.Cm writable
which mounts the volume read-only or read/write, respectively.
The
.Ar nosuid
argument must be either
.Cm suid
or
.Cm nosuid .
That argument is passed as a mount option.
The
.Ar nodev
argument must be either
.Cm dev
or
.Cm nodev .
That argument is passed as a mount option.
.It Fl u Ar device
Deprecated.
Unmount the file system on
.Ar device .
If the unmount is successful, the exit status is 253.
.El
.Sh FILES
The
.Nm
command is installed in the
.Pa /System/Library/Filesystems/exfat.fs/Contents/Resources
directory, which is typically not in a shell's search path.
.Sh COMPATIBILITY
The
.Fl m
and
.Fl u
options are deprecated.
The preferred way to mount an ExFAT volume is to let
.Xr diskarbitrationd 8
mount it automatically when the device is discovered, or use the
.Xr diskutil 8
command to explicitly mount a device.
You may also use the
.Xr mount 8
or
.Xr mount_exfat 8
commands directly.
The preferred way to unmount an ExFAT volume is with the
.Xr diskutil 8
command.
Note that using the
.Xr umount 8
command usually will not work because various process are likely to have open
files, which will prevent the unmount.
The
.Xr diskutil 8
command will send a notification that causes many such processes to close their
open files so that the unmount will succeed.
.Sh SEE ALSO 
.Xr mount_exfat 8 ,
.Xr fsck_exfat 8 ,
.Xr diskarbitrationd 8,
.Xr diskutil 8 ,
.Xr uuid 3,
.Xr uuid_unparse 3 ,
.Xr uuid_generate 3 ,
.Xr getattrlist 2
.Sh HISTORY
The
.Nm
utility first appeared in Mac OS X 10.6.3.
.Sh BUGS
The choice of non-zero exit status to indicate success was an unfortunate design decision.
.Pp
The
.Fl u
option usually does not work since several processes in Mac OS X leave files open on
mounted volumes, thus preventing the unmount.
The
.Xr diskutil 8
command is preferred for unmounting.