2697 lines
81 KiB
Groff
2697 lines
81 KiB
Groff
.\" Copyright (c) 1996-2004 Andries Brouwer
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.\" Copyright (C) 2006-2012 Karel Zak <kzak@redhat.com>
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.\"
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.\" This page is somewhat derived from a page that was
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.\" (c) 1980, 1989, 1991 The Regents of the University of California
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.\" and had been heavily modified by Rik Faith and myself.
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.\" (Probably no BSD text remains.)
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.\" Fragments of text were written by Werner Almesberger, Remy Card,
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.\" Stephen Tweedie and Eric Youngdale.
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public License along
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.\" with this program; if not, write to the Free Software Foundation, Inc.,
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.\" 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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.\"
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.TH MOUNT 8 "August 2015" "util-linux" "System Administration"
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.SH NAME
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mount \- mount a filesystem
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.SH SYNOPSIS
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.B mount
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.RB [ \-l | \-h | \-V ]
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.LP
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.B mount \-a
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.RB [ \-fFnrsvw ]
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.RB [ \-t
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.IR fstype ]
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.RB [ \-O
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.IR optlist ]
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.LP
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.B mount
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.RB [ \-fnrsvw ]
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.RB [ \-o
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.IR options ]
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.IR device | dir
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.LP
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.B mount
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.RB [ \-fnrsvw ]
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.RB [ \-t
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.IB fstype ]
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.RB [ \-o
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.IR options ]
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.I device dir
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.SH DESCRIPTION
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All files accessible in a Unix system are arranged in one big
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tree, the file hierarchy, rooted at
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.IR / .
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These files can be spread out over several devices. The
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.B mount
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command serves to attach the filesystem found on some device
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to the big file tree. Conversely, the
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.BR umount (8)
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command will detach it again. The filesystem is used to control how data is
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stored on the device or provided in a virtual way by network or another services.
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The standard form of the
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.B mount
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command is:
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.RS
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.br
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.BI "mount \-t" " type device dir"
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.br
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.RE
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This tells the kernel to attach the filesystem found on
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.I device
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(which is of type
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.IR type )
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at the directory
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.IR dir .
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The option \fB\-t \fItype\fR is optional. The
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.B mount
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command is usually able to detect a filesystem. The root permissions are necessary
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to mount a filesystem by default. See section "Non-superuser mounts" below for more details.
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The previous contents (if any) and owner and mode of
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.I dir
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become invisible, and as long as this filesystem remains mounted,
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the pathname
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.I dir
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refers to the root of the filesystem on
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.IR device .
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If only the directory or the device is given, for example:
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.RS
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.sp
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.B mount /dir
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.sp
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.RE
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|
then \fBmount\fR looks for a mountpoint (and if not found then for a device) in the
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.I /etc/fstab
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file. It's possible to use the
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.B \-\-target
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or
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|
.B \-\-source
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|
options to avoid ambivalent interpretation of the given argument. For example:
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|
.RS
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.sp
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.B mount \-\-target /mountpoint
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.sp
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.RE
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The same filesystem may be mounted more than once, and in some cases (e.g.,
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network filesystems) the same filesystem may be mounted on the same
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mountpoint more times. The mount command does not implement any policy to
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control this behavior. All behavior is controlled by the kernel and it is usually
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specific to the filesystem driver. The exception is \fB\-\-all\fR, in this case
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already mounted filesystems are ignored (see \fB\-\-all\fR below for more details).
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.SS Listing the mounts
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The listing mode is maintained for backward compatibility only.
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For more robust and customizable output use
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.BR findmnt (8),
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\fBespecially in your scripts\fP. Note that control characters in the
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mountpoint name are replaced with '?'.
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The following command lists all mounted filesystems (of type
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.IR type ):
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.RS
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.sp
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.BR "mount " [ \-l "] [" "\-t \fItype\/\fP" ]
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.sp
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.RE
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The option \fB\-l\fR adds labels to this listing. See below.
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.SS Indicating the device and filesystem
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Most devices are indicated by a filename (of a block special device), like
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.IR /dev/sda1 ,
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but there are other possibilities. For example, in the case of an NFS mount,
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.I device
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may look like
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.IR knuth.cwi.nl:/dir .
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It is also possible to indicate a block special device using its filesystem label
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or UUID (see the \fB\-L\fR and \fB\-U\fR options below), or its partition label
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or UUID. Partition identifiers are supported for example for GUID Partition
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Tables (GPT).
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The device names of disk partitions are unstable; hardware reconfiguration,
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adding or removing a device can cause changes in names. This is the reason why it's
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strongly recommended to use filesystem or partition identifiers like UUID or
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LABEL.
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The command \fBlsblk \-\-fs\fR provides an overview of filesystems, LABELs and UUIDs
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on available block devices. The command \fBblkid \-p <device>\fR provides details about
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a filesystem on the specified device.
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Don't forget that there is no guarantee that UUIDs and labels are really
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unique, especially if you move, share or copy the device. Use
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.B "lsblk \-o +UUID,PARTUUID"
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to verify that the UUIDs are really unique in your system.
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The recommended setup is to use tags (e.g.\& \fBUUID=\fIuuid\fR) rather than
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.I /dev/disk/by-{label,uuid,partuuid,partlabel}
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udev symlinks in the
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.I /etc/fstab
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file. Tags are
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more readable, robust and portable. The
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.BR mount (8)
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command internally uses udev
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symlinks, so the use of symlinks in /etc/fstab has no advantage over tags.
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For more details see
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.BR libblkid (3).
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Note that
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.BR mount (8)
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uses UUIDs as strings. The UUIDs from the command line or from
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.BR fstab (5)
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are not converted to internal binary representation. The string representation
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of the UUID should be based on lower case characters.
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The
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.I proc
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filesystem is not associated with a special device, and when
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mounting it, an arbitrary keyword, such as
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.I proc
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can be used instead of a device specification.
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(The customary choice
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.I none
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is less fortunate: the error message `none already mounted' from
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.B mount
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can be confusing.)
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.SS The files /etc/fstab, /etc/mtab and /proc/mounts
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The file
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.I /etc/fstab
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(see
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.BR fstab (5)),
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|
may contain lines describing what devices are usually
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mounted where, using which options. The default location of the
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.BR fstab (5)
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|
file can be overridden with the
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|
.BI \-\-fstab " path"
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|
command-line option (see below for more details).
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.LP
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|
The command
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.RS
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.sp
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.B mount \-a
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.RB [ \-t
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.IR type ]
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.RB [ \-O
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.IR optlist ]
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.sp
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.RE
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|
(usually given in a bootscript) causes all filesystems mentioned in
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|
.I fstab
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(of the proper type and/or having or not having the proper options)
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|
to be mounted as indicated, except for those whose line contains the
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|
.B noauto
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|
keyword. Adding the
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|
.B \-F
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|
option will make \fBmount\fR fork, so that the
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filesystems are mounted simultaneously.
|
|
.LP
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|
When mounting a filesystem mentioned in
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.I fstab
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or
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.IR mtab ,
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|
it suffices to specify on the command line only the device, or only the mount point.
|
|
.sp
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|
The programs
|
|
.B mount
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|
and
|
|
.B umount
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|
traditionally maintained a list of currently mounted filesystems in the file
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.IR /etc/mtab .
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|
The support for regular classic
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.I /etc/mtab
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|
is completely disabled in compile time by default, because on current Linux
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|
systems it is better to make it a symlink to
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.I /proc/mounts
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|
instead. The regular mtab file maintained in userspace cannot reliably
|
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work with namespaces, containers and other advanced Linux features.
|
|
If the regular mtab support is enabled than it's possible to
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use the file as well as the symlink.
|
|
.sp
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|
If no arguments are given to
|
|
.BR mount ,
|
|
the list of mounted filesystems is printed.
|
|
.sp
|
|
If you want to override mount options from
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.I /etc/fstab
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|
you have to use the \fB\-o\fR option:
|
|
.RS
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|
.sp
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|
.BI mount " device" \fR| "dir " \-o " options"
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|
.sp
|
|
.RE
|
|
and then the mount options from the command line will be appended to
|
|
the list of options from
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.IR /etc/fstab .
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|
This default behaviour is possible to change by command line
|
|
option \fB\-\-options\-mode\fR.
|
|
The usual behavior is that the last option wins if there are conflicting
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|
ones.
|
|
.sp
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|
The
|
|
.B mount
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program does not read the
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.I /etc/fstab
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file if both
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|
.I device
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|
(or LABEL, UUID, PARTUUID or PARTLABEL) and
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|
.I dir
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|
are specified. For example, to mount device
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|
.BR foo " at " /dir :
|
|
.RS
|
|
.sp
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|
.B "mount /dev/foo /dir"
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|
.sp
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|
.RE
|
|
This default behaviour is possible to change by command line option
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|
\fB\-\-options\-source\-force\fR to always read configuration from fstab. For
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non-root users
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.B mount
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|
always read fstab configuration.
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|
|
.SS Non-superuser mounts
|
|
Normally, only the superuser can mount filesystems.
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|
However, when
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|
.I fstab
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|
contains the
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|
.B user
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|
option on a line, anybody can mount the corresponding filesystem.
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|
.LP
|
|
Thus, given a line
|
|
.RS
|
|
.sp
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.B "/dev/cdrom /cd iso9660 ro,user,noauto,unhide"
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|
.sp
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|
.RE
|
|
any user can mount the iso9660 filesystem found on an inserted CDROM
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|
using the command:
|
|
.RS
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|
.B "mount /cd"
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|
.sp
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|
.RE
|
|
Note that \fBmount\fR is very strict about non-root users and all paths
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|
specified on command line are verified before fstab is parsed or a helper
|
|
program is executed. It's strongly recommended to use a valid mountpoint to
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specify filesystem, otherwise \fBmount\fR may fail. For example it's bad idea
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|
to use NFS or CIFS source on command line.
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|
.PP
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Since version 2.35 \fBmount\fR command does not exit when user permissions are
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inadequate by internal libmount security rules. It drops suid permissions
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and continue as regular non-root user. It allows to support use-cases where
|
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root permissions are not necessary (e.g., fuse filesystems, user namespaces,
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etc).
|
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.PP
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For more details, see
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.BR fstab (5).
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|
Only the user that mounted a filesystem can unmount it again.
|
|
If any user should be able to unmount it, then use
|
|
.B users
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|
instead of
|
|
.B user
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|
in the
|
|
.I fstab
|
|
line.
|
|
The
|
|
.B owner
|
|
option is similar to the
|
|
.B user
|
|
option, with the restriction that the user must be the owner
|
|
of the special file. This may be useful e.g.\& for
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.I /dev/fd
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if a login script makes the console user owner of this device.
|
|
The
|
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.B group
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|
option is similar, with the restriction that the user must be
|
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member of the group of the special file.
|
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.SS Bind mount operation
|
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Remount part of the file hierarchy somewhere else. The call is:
|
|
|
|
.RS
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.br
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.B mount \-\-bind
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.I olddir newdir
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.RE
|
|
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|
or by using this fstab entry:
|
|
|
|
.RS
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.br
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.BI / olddir
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.BI / newdir
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.B none bind
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.RE
|
|
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|
After this call the same contents are accessible in two places.
|
|
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|
It is important to understand that "bind" does not to create any second-class
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or special node in the kernel VFS. The "bind" is just another operation to
|
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attach a filesystem. There is nowhere stored information that the filesystem
|
|
has been attached by "bind" operation. The \fIolddir\fR and \fInewdir\fR are
|
|
independent and the \fIolddir\fR may be umounted.
|
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|
One can also remount a single file (on a single file). It's also
|
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possible to use the bind mount to create a mountpoint from a regular
|
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directory, for example:
|
|
|
|
.RS
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.br
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.B mount \-\-bind foo foo
|
|
.RE
|
|
|
|
The bind mount call attaches only (part of) a single filesystem, not possible
|
|
submounts. The entire file hierarchy including submounts is attached
|
|
a second place by using:
|
|
|
|
.RS
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|
.br
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|
.B mount \-\-rbind
|
|
.I olddir newdir
|
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.RE
|
|
|
|
Note that the filesystem mount options maintained by kernel will remain the same as those
|
|
on the original mount point. The userspace mount options (e.g., _netdev) will not be copied
|
|
by
|
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.BR mount (8)
|
|
and it's necessary explicitly specify the options on mount command line.
|
|
|
|
.BR mount (8)
|
|
since v2.27 allows to change the mount options by passing the
|
|
relevant options along with
|
|
.BR \-\-bind .
|
|
For example:
|
|
|
|
.RS
|
|
.br
|
|
.B mount \-o bind,ro foo foo
|
|
.RE
|
|
|
|
This feature is not supported by the Linux kernel; it is implemented in userspace
|
|
by an additional \fBmount\fR(2) remounting system call.
|
|
This solution is not atomic.
|
|
|
|
The alternative (classic) way to create a read-only bind mount is to use the remount
|
|
operation, for example:
|
|
|
|
.RS
|
|
.br
|
|
.B mount \-\-bind
|
|
.I olddir newdir
|
|
.br
|
|
.B mount \-o remount,bind,ro
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|
.I olddir newdir
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|
.RE
|
|
|
|
Note that a read-only bind will create a read-only mountpoint (VFS entry),
|
|
but the original filesystem superblock will still be writable, meaning that the
|
|
.I olddir
|
|
will be writable, but the
|
|
.I newdir
|
|
will be read-only.
|
|
|
|
It's also possible to change nosuid, nodev, noexec, noatime, nodiratime and
|
|
relatime VFS entry flags by "remount,bind" operation. The another (for example
|
|
filesystem specific flags) are silently ignored. It's impossible to change mount
|
|
options recursively (for example with \fB\-o rbind,ro\fR).
|
|
|
|
.BR mount (8)
|
|
since v2.31 ignores the \fBbind\fR flag from
|
|
.I /etc/fstab
|
|
on
|
|
.B remount operation
|
|
(if "\-o remount" specified on command line). This is necessary to fully control
|
|
mount options on remount by command line. In the previous versions the bind
|
|
flag has been always applied and it was impossible to re-define mount options
|
|
without interaction with the bind semantic. This
|
|
.BR mount (8)
|
|
behavior does not affect situations when "remount,bind" is specified in the
|
|
.I /etc/fstab
|
|
file.
|
|
|
|
.SS The move operation
|
|
Move a
|
|
.B mounted tree
|
|
to another place (atomically). The call is:
|
|
|
|
.RS
|
|
.br
|
|
.B mount \-\-move
|
|
.I olddir newdir
|
|
.RE
|
|
|
|
This will cause the contents which previously appeared under
|
|
.I olddir
|
|
to now be accessible under
|
|
.IR newdir .
|
|
The physical location of the files is not changed.
|
|
Note that
|
|
.I olddir
|
|
has to be a mountpoint.
|
|
|
|
Note also that moving a mount residing under a shared mount is invalid and
|
|
unsupported. Use
|
|
.B findmnt \-o TARGET,PROPAGATION
|
|
to see the current propagation flags.
|
|
|
|
.SS Shared subtree operations
|
|
Since Linux 2.6.15 it is possible to mark a mount and its submounts as shared,
|
|
private, slave or unbindable. A shared mount provides the ability to create mirrors
|
|
of that mount such that mounts and unmounts within any of the mirrors propagate
|
|
to the other mirror. A slave mount receives propagation from its master, but
|
|
not vice versa. A private mount carries no propagation abilities. An
|
|
unbindable mount is a private mount which cannot be cloned through a bind
|
|
operation. The detailed semantics are documented in
|
|
.I Documentation/filesystems/sharedsubtree.txt
|
|
file in the kernel source tree.
|
|
|
|
Supported operations are:
|
|
|
|
.RS
|
|
.nf
|
|
.BI "mount \-\-make\-shared " mountpoint
|
|
.BI "mount \-\-make\-slave " mountpoint
|
|
.BI "mount \-\-make\-private " mountpoint
|
|
.BI "mount \-\-make\-unbindable " mountpoint
|
|
.fi
|
|
.RE
|
|
|
|
The following commands allow one to recursively change the type of all the
|
|
mounts under a given mountpoint.
|
|
|
|
.RS
|
|
.nf
|
|
.BI "mount \-\-make\-rshared " mountpoint
|
|
.BI "mount \-\-make\-rslave " mountpoint
|
|
.BI "mount \-\-make\-rprivate " mountpoint
|
|
.BI "mount \-\-make\-runbindable " mountpoint
|
|
.fi
|
|
.RE
|
|
|
|
.BR mount (8)
|
|
.B does not read
|
|
.BR fstab (5)
|
|
when a \fB\-\-make-\fR* operation is requested. All necessary information has to be
|
|
specified on the command line.
|
|
|
|
Note that the Linux kernel does not allow to change multiple propagation flags
|
|
with a single
|
|
.BR mount (2)
|
|
system call, and the flags cannot be mixed with other mount options and operations.
|
|
|
|
Since util-linux 2.23 the \fBmount\fR command allows to do more propagation
|
|
(topology) changes by one mount(8) call and do it also together with other
|
|
mount operations. This feature is EXPERIMENTAL. The propagation flags are applied
|
|
by additional \fBmount\fR(2) system calls when the preceding mount operations
|
|
were successful. Note that this use case is not atomic. It is possible to
|
|
specify the propagation flags in
|
|
.BR fstab (5)
|
|
as mount options
|
|
.RB ( private ,
|
|
.BR slave ,
|
|
.BR shared ,
|
|
.BR unbindable ,
|
|
.BR rprivate ,
|
|
.BR rslave ,
|
|
.BR rshared ,
|
|
.BR runbindable ).
|
|
|
|
For example:
|
|
|
|
.RS
|
|
.nf
|
|
.B mount \-\-make\-private \-\-make\-unbindable /dev/sda1 /foo
|
|
.fi
|
|
.RE
|
|
|
|
is the same as:
|
|
|
|
.RS
|
|
.nf
|
|
.B mount /dev/sda1 /foo
|
|
.B mount \-\-make\-private /foo
|
|
.B mount \-\-make\-unbindable /foo
|
|
.fi
|
|
.RE
|
|
|
|
.SH COMMAND-LINE OPTIONS
|
|
The full set of mount options used by an invocation of
|
|
.B mount
|
|
is determined by first extracting the
|
|
mount options for the filesystem from the
|
|
.I fstab
|
|
table, then applying any options specified by the
|
|
.B \-o
|
|
argument, and finally applying a
|
|
.BR \-r " or " \-w
|
|
option, when present.
|
|
|
|
The command \fBmount\fR does not pass all command-line options to the
|
|
\fB/sbin/mount.\fIsuffix\fR mount helpers. The interface between \fBmount\fR
|
|
and the mount helpers is described below in the section \fBEXTERNAL HELPERS\fR.
|
|
.sp
|
|
Command-line options available for the
|
|
.B mount
|
|
command are:
|
|
.TP
|
|
.BR \-a , " \-\-all"
|
|
Mount all filesystems (of the given types) mentioned in
|
|
.I fstab
|
|
(except for those whose line contains the
|
|
.B noauto
|
|
keyword). The filesystems are mounted following their order in
|
|
.IR fstab .
|
|
The mount command compares filesystem source, target (and fs root for bind
|
|
mount or btrfs) to detect already mounted filesystems. The kernel table with
|
|
already mounted filesystems is cached during \fBmount \-\-all\fR. It means
|
|
that all duplicated fstab entries will be mounted.
|
|
.sp
|
|
The option \fB\-\-all\fR is possible to use for remount operation too. In this
|
|
case all filters (\fB\-t\fR and \fB\-O\fR) are applied to the table of already
|
|
mounted filesystems.
|
|
.sp
|
|
Since version 2.35 is possible to use the command line option \fB\-o\fR to
|
|
alter mount options from fstab (see also \fB\-\-options\-mode\fR).
|
|
.sp
|
|
Note that it is a bad practice to use \fBmount \-a\fR for
|
|
.I fstab
|
|
checking. The recommended solution is \fBfindmnt \-\-verify\fR.
|
|
.TP
|
|
.BR \-B , " \-\-bind"
|
|
Remount a subtree somewhere else (so that its contents are available
|
|
in both places). See above, under \fBBind mounts\fR.
|
|
.TP
|
|
.BR \-c , " \-\-no\-canonicalize"
|
|
Don't canonicalize paths. The mount command canonicalizes all paths
|
|
(from command line or fstab) by default. This option can be used
|
|
together with the
|
|
.B \-f
|
|
flag for already canonicalized absolute paths. The option is designed for mount
|
|
helpers which call \fBmount \-i\fR. It is strongly recommended to not use this
|
|
command-line option for normal mount operations.
|
|
.sp
|
|
Note that \fBmount\fR(8) does not pass this option to the
|
|
\fB/sbin/mount.\fItype\fR helpers.
|
|
.TP
|
|
.BR \-F , " \-\-fork"
|
|
(Used in conjunction with
|
|
.BR \-a .)
|
|
Fork off a new incarnation of \fBmount\fR for each device.
|
|
This will do the mounts on different devices or different NFS servers
|
|
in parallel.
|
|
This has the advantage that it is faster; also NFS timeouts go in
|
|
parallel. A disadvantage is that the mounts are done in undefined order.
|
|
Thus, you cannot use this option if you want to mount both
|
|
.I /usr
|
|
and
|
|
.IR /usr/spool .
|
|
.IP "\fB\-f, \-\-fake\fP"
|
|
Causes everything to be done except for the actual system call; if it's not
|
|
obvious, this ``fakes'' mounting the filesystem. This option is useful in
|
|
conjunction with the
|
|
.B \-v
|
|
flag to determine what the
|
|
.B mount
|
|
command is trying to do. It can also be used to add entries for devices
|
|
that were mounted earlier with the \fB\-n\fR option. The \fB\-f\fR option
|
|
checks for an existing record in /etc/mtab and fails when the record already
|
|
exists (with a regular non-fake mount, this check is done by the kernel).
|
|
.IP "\fB\-i, \-\-internal\-only\fP"
|
|
Don't call the \fB/sbin/mount.\fIfilesystem\fR helper even if it exists.
|
|
.TP
|
|
.BR \-L , " \-\-label " \fIlabel
|
|
Mount the partition that has the specified
|
|
.IR label .
|
|
.TP
|
|
.BR \-l , " \-\-show\-labels"
|
|
Add the labels in the mount output. \fBmount\fR must have
|
|
permission to read the disk device (e.g.\& be set-user-ID root) for this to work.
|
|
One can set such a label for ext2, ext3 or ext4 using the
|
|
.BR e2label (8)
|
|
utility, or for XFS using
|
|
.BR xfs_admin (8),
|
|
or for reiserfs using
|
|
.BR reiserfstune (8).
|
|
.TP
|
|
.BR \-M , " \-\-move"
|
|
Move a subtree to some other place. See above, the subsection
|
|
\fBThe move operation\fR.
|
|
.TP
|
|
.BR \-n , " \-\-no\-mtab"
|
|
Mount without writing in
|
|
.IR /etc/mtab .
|
|
This is necessary for example when
|
|
.I /etc
|
|
is on a read-only filesystem.
|
|
.TP
|
|
.BR \-N , " \-\-namespace " \fIns
|
|
Perform mount in namespace specified by \fIns\fR.
|
|
\fIns\fR is either PID of process running in that namespace
|
|
or special file representing that namespace.
|
|
.sp
|
|
.BR mount (8)
|
|
switches to the namespace when it reads /etc/fstab, writes /etc/mtab (or writes to /run/mount) and calls
|
|
.BR mount (2)
|
|
system call, otherwise it runs in the original namespace. It means that the target namespace does not have
|
|
to contain any libraries or another requirements necessary to execute
|
|
.BR mount (2)
|
|
command.
|
|
.sp
|
|
See \fBnamespaces\fR(7) for more information.
|
|
.TP
|
|
.BR \-O , " \-\-test\-opts " \fIopts
|
|
Limit the set of filesystems to which the
|
|
.B \-a
|
|
option applies. In this regard it is like the
|
|
.B \-t
|
|
option except that
|
|
.B \-O
|
|
is useless without
|
|
.BR \-a .
|
|
For example, the command:
|
|
.RS
|
|
.RS
|
|
.sp
|
|
.B "mount \-a \-O no_netdev"
|
|
.sp
|
|
.RE
|
|
mounts all filesystems except those which have the option
|
|
.I _netdev
|
|
specified in the options field in the
|
|
.I /etc/fstab
|
|
file.
|
|
|
|
It is different from
|
|
.B \-t
|
|
in that each option is matched exactly; a leading
|
|
.B no
|
|
at the beginning of one option does not negate the rest.
|
|
|
|
The
|
|
.B \-t
|
|
and
|
|
.B \-O
|
|
options are cumulative in effect; that is, the command
|
|
.RS
|
|
.sp
|
|
.B "mount \-a \-t ext2 \-O _netdev"
|
|
.sp
|
|
.RE
|
|
mounts all ext2 filesystems with the _netdev option, not all filesystems
|
|
that are either ext2 or have the _netdev option specified.
|
|
.RE
|
|
.TP
|
|
.BR \-o , " \-\-options " \fIopts
|
|
Use the specified mount options. The \fIopts\fR argument is
|
|
a comma-separated list. For example:
|
|
.RS
|
|
.RS
|
|
.sp
|
|
.B "mount LABEL=mydisk \-o noatime,nodev,nosuid"
|
|
.sp
|
|
.RE
|
|
|
|
For more details, see the
|
|
.B FILESYSTEM-INDEPENDENT MOUNT OPTIONS
|
|
and
|
|
.B FILESYSTEM-SPECIFIC MOUNT OPTIONS
|
|
sections.
|
|
.RE
|
|
|
|
.TP
|
|
.BR "\-\-options\-mode " \fImode
|
|
Controls how to combine options from fstab/mtab with options from command line.
|
|
\fImode\fR can be one of
|
|
.BR ignore ", " append ", " prepend " or " replace .
|
|
For example \fBappend\fR means that options from fstab are appended to options from command line.
|
|
Default value is \fBprepend\fR -- it means command line options are evaluated after fstab options.
|
|
Note that the last option wins if there are conflicting ones.
|
|
|
|
.TP
|
|
.BR "\-\-options\-source " \fIsource
|
|
Source of default options.
|
|
\fIsource\fR is comma separated list of
|
|
.BR fstab ", " mtab " and " disable .
|
|
\fBdisable\fR disables
|
|
.BR fstab " and " mtab
|
|
and disables \fB\-\-options\-source\-force\fR.
|
|
Default value is \fBfstab,mtab\fR.
|
|
|
|
.TP
|
|
.B \-\-options\-source\-force
|
|
Use options from fstab/mtab even if both \fIdevice\fR and \fIdir\fR are specified.
|
|
|
|
.TP
|
|
.BR \-R , " \-\-rbind"
|
|
Remount a subtree and all possible submounts somewhere else (so that its
|
|
contents are available in both places). See above, the subsection
|
|
\fBBind mounts\fR.
|
|
.TP
|
|
.BR \-r , " \-\-read\-only"
|
|
Mount the filesystem read-only. A synonym is
|
|
.BR "\-o ro" .
|
|
.sp
|
|
Note that, depending on the filesystem type, state and kernel behavior, the
|
|
system may still write to the device. For example, ext3 and ext4 will replay the
|
|
journal if the filesystem is dirty. To prevent this kind of write access, you
|
|
may want to mount an ext3 or ext4 filesystem with the \fBro,noload\fR mount
|
|
options or set the block device itself to read-only mode, see the
|
|
.BR blockdev (8)
|
|
command.
|
|
.TP
|
|
.B \-s
|
|
Tolerate sloppy mount options rather than failing. This will ignore mount
|
|
options not supported by a filesystem type. Not all filesystems support this
|
|
option. Currently it's supported by the \fBmount.nfs\fR mount helper only.
|
|
.TP
|
|
.BI \-\-source " device"
|
|
If only one argument for the mount command is given then the argument might be
|
|
interpreted as target (mountpoint) or source (device). This option allows to
|
|
explicitly define that the argument is the mount source.
|
|
.TP
|
|
.BI \-\-target " directory"
|
|
If only one argument for the mount command is given then the argument might be
|
|
interpreted as target (mountpoint) or source (device). This option allows to
|
|
explicitly define that the argument is the mount target.
|
|
.TP
|
|
.BI \-\-target\-prefix " directory"
|
|
Prepend specified directory to all mount targets. This option allows to follow
|
|
fstab, but mount operations is done on another place, for example:
|
|
.RS
|
|
.RS
|
|
.sp
|
|
.B "mount \-\-all \-\-target\-prefix /chroot \-o X\-mount.mkdir
|
|
.sp
|
|
.RE
|
|
mounts all from system fstab to /chroot, all missing muontpoint are created
|
|
(due to X-mount.mkdir). See also \fB\-\-fstab\fP to use an alternative fstab.
|
|
.RE
|
|
.TP
|
|
.BR \-T , " \-\-fstab " \fIpath
|
|
Specifies an alternative fstab file. If \fIpath\fP is a directory then the files
|
|
in the directory are sorted by
|
|
.BR strverscmp (3);
|
|
files that start with "."\& or without an \&.fstab extension are ignored. The option
|
|
can be specified more than once. This option is mostly designed for initramfs
|
|
or chroot scripts where additional configuration is specified beyond standard
|
|
system configuration.
|
|
.sp
|
|
Note that \fBmount\fR(8) does not pass the option \fB\-\-fstab\fP to the
|
|
\fB/sbin/mount.\fItype\fR helpers, meaning that the alternative fstab files will be
|
|
invisible for the helpers. This is no problem for normal mounts, but user
|
|
(non-root) mounts always require fstab to verify the user's rights.
|
|
.TP
|
|
.BR \-t , " \-\-types " \fIfstype
|
|
The argument following the
|
|
.B \-t
|
|
is used to indicate the filesystem type. The filesystem types which are
|
|
currently supported depend on the running kernel. See
|
|
.I /proc/filesystems
|
|
and
|
|
.I /lib/modules/$(uname \-r)/kernel/fs
|
|
for a complete list of the filesystems. The most common are ext2, ext3, ext4,
|
|
xfs, btrfs, vfat, sysfs, proc, nfs and cifs.
|
|
.sp
|
|
The programs
|
|
.B mount
|
|
and
|
|
.B umount
|
|
support filesystem subtypes. The subtype is defined by a '.subtype' suffix. For
|
|
example 'fuse.sshfs'. It's recommended to use subtype notation rather than add
|
|
any prefix to the mount source (for example 'sshfs#example.com' is
|
|
deprecated).
|
|
|
|
If no
|
|
.B \-t
|
|
option is given, or if the
|
|
.B auto
|
|
type is specified, mount will try to guess the desired type.
|
|
Mount uses the blkid library for guessing the filesystem
|
|
type; if that does not turn up anything that looks familiar,
|
|
mount will try to read the file
|
|
.IR /etc/filesystems ,
|
|
or, if that does not exist,
|
|
.IR /proc/filesystems .
|
|
All of the filesystem types listed there will be tried,
|
|
except for those that are labeled "nodev" (e.g.\&
|
|
.IR devpts ,
|
|
.I proc
|
|
and
|
|
.IR nfs ).
|
|
If
|
|
.I /etc/filesystems
|
|
ends in a line with a single *, mount will read
|
|
.I /proc/filesystems
|
|
afterwards. While trying, all filesystem types will be
|
|
mounted with the mount option \fBsilent\fR.
|
|
.sp
|
|
The
|
|
.B auto
|
|
type may be useful for user-mounted floppies.
|
|
Creating a file
|
|
.I /etc/filesystems
|
|
can be useful to change the probe order (e.g., to try vfat before msdos
|
|
or ext3 before ext2) or if you use a kernel module autoloader.
|
|
.sp
|
|
More than one type may be specified in a comma-separated
|
|
list, for option
|
|
.B \-t
|
|
as well as in an
|
|
.I /etc/fstab
|
|
entry. The list of filesystem types for option
|
|
.B \-t
|
|
can be prefixed with
|
|
.B no
|
|
to specify the filesystem types on which no action should be taken.
|
|
The prefix
|
|
.B no
|
|
has no effect when specified in an
|
|
.I /etc/fstab
|
|
entry.
|
|
.sp
|
|
The prefix
|
|
.B no
|
|
can be meaningful with the
|
|
.B \-a
|
|
option. For example, the command
|
|
.RS
|
|
.RS
|
|
.sp
|
|
.B "mount \-a \-t nomsdos,smbfs"
|
|
.sp
|
|
.RE
|
|
mounts all filesystems except those of type
|
|
.I msdos
|
|
and
|
|
.IR smbfs .
|
|
.sp
|
|
For most types all the
|
|
.B mount
|
|
program has to do is issue a simple
|
|
.BR mount (2)
|
|
system call, and no detailed knowledge of the filesystem type is required.
|
|
For a few types however (like nfs, nfs4, cifs, smbfs, ncpfs) an ad hoc code is
|
|
necessary. The nfs, nfs4, cifs, smbfs, and ncpfs filesystems
|
|
have a separate mount program. In order to make it possible to
|
|
treat all types in a uniform way, \fBmount\fR will execute the program
|
|
.BI /sbin/mount. type
|
|
(if that exists) when called with type
|
|
.IR type .
|
|
Since different versions of the
|
|
.B smbmount
|
|
program have different calling conventions,
|
|
.B /sbin/mount.smbfs
|
|
may have to be a shell script that sets up the desired call.
|
|
.RE
|
|
.TP
|
|
.BR \-U , " \-\-uuid " \fIuuid
|
|
Mount the partition that has the specified
|
|
.IR uuid .
|
|
.TP
|
|
.BR \-v , " \-\-verbose"
|
|
Verbose mode.
|
|
.TP
|
|
.BR \-w , " \-\-rw" , " \-\-read\-write"
|
|
Mount the filesystem read/write. The read-write is kernel default and
|
|
.BR mount (8)
|
|
default is to try read-only if the previous mount syscall with read-write flags
|
|
on write-protected devices of filesystems failed.
|
|
.sp
|
|
A synonym is
|
|
.BR "\-o rw" .
|
|
|
|
Note that specify \fB\-w\fR on command line forces \fBmount\fR command to never
|
|
try read-only mount on write-protected devices or already mounted read-only
|
|
filesystems.
|
|
.TP
|
|
.BR \-V , " \-\-version"
|
|
Display version information and exit.
|
|
.TP
|
|
.BR \-h , " \-\-help"
|
|
Display help text and exit.
|
|
|
|
.SH FILESYSTEM-INDEPENDENT MOUNT OPTIONS
|
|
Some of these options are only useful when they appear in the
|
|
.I /etc/fstab
|
|
file.
|
|
|
|
Some of these options could be enabled or disabled by default
|
|
in the system kernel. To check the current setting see the options
|
|
in /proc/mounts. Note that filesystems also have per-filesystem
|
|
specific default mount options (see for example \fBtune2fs \-l\fP
|
|
output for extN filesystems).
|
|
|
|
The following options apply to any filesystem that is being
|
|
mounted (but not every filesystem actually honors them \(en e.g.\&, the
|
|
.B sync
|
|
option today has an effect only for ext2, ext3, ext4, fat, vfat, ufs and xfs):
|
|
|
|
.TP
|
|
.B async
|
|
All I/O to the filesystem should be done asynchronously. (See also the
|
|
.B sync
|
|
option.)
|
|
.TP
|
|
.B atime
|
|
Do not use the \fBnoatime\fR feature, so the inode access time is controlled
|
|
by kernel defaults. See also the descriptions of the \fB\%relatime\fR and
|
|
.B strictatime
|
|
mount options.
|
|
.TP
|
|
.B noatime
|
|
Do not update inode access times on this filesystem (e.g.\& for faster
|
|
access on the news spool to speed up news servers). This works for all
|
|
inode types (directories too), so it implies \fB\%nodiratime\fR.
|
|
.TP
|
|
.B auto
|
|
Can be mounted with the
|
|
.B \-a
|
|
option.
|
|
.TP
|
|
.B noauto
|
|
Can only be mounted explicitly (i.e., the
|
|
.B \-a
|
|
option will not cause the filesystem to be mounted).
|
|
.TP
|
|
.na
|
|
.BR context=\fIcontext ", " fscontext=\fIcontext ", " defcontext=\fIcontext ", and " \%rootcontext=\fIcontext
|
|
.ad
|
|
The
|
|
.B context=
|
|
option is useful when mounting filesystems that do not support
|
|
extended attributes, such as a floppy or hard disk formatted with VFAT, or
|
|
systems that are not normally running under SELinux, such as an ext3 or ext4 formatted
|
|
|
|
disk from a non-SELinux workstation. You can also use
|
|
.B context=
|
|
on filesystems you do not trust, such as a floppy. It also helps in compatibility with
|
|
xattr-supporting filesystems on earlier 2.4.<x> kernel versions. Even where
|
|
xattrs are supported, you can save time not having to label every file by
|
|
assigning the entire disk one security context.
|
|
|
|
A commonly used option for removable media is
|
|
.BR \%context="system_u:object_r:removable_t" .
|
|
|
|
Two other options are
|
|
.B fscontext=
|
|
and
|
|
.BR defcontext= ,
|
|
both of which are mutually exclusive of the context option. This means you
|
|
can use fscontext and defcontext with each other, but neither can be used with
|
|
context.
|
|
|
|
The
|
|
.B fscontext=
|
|
option works for all filesystems, regardless of their xattr
|
|
support. The fscontext option sets the overarching filesystem label to a
|
|
specific security context. This filesystem label is separate from the
|
|
individual labels on the files. It represents the entire filesystem for
|
|
certain kinds of permission checks, such as during mount or file creation.
|
|
Individual file labels are still obtained from the xattrs on the files
|
|
themselves. The context option actually sets the aggregate context that
|
|
fscontext provides, in addition to supplying the same label for individual
|
|
files.
|
|
|
|
You can set the default security context for unlabeled files using
|
|
.B defcontext=
|
|
option. This overrides the value set for unlabeled files in the policy and requires a
|
|
filesystem that supports xattr labeling.
|
|
|
|
The
|
|
.B rootcontext=
|
|
option allows you to explicitly label the root inode of a FS being mounted
|
|
before that FS or inode becomes visible to userspace. This was found to be
|
|
useful for things like stateless linux.
|
|
|
|
Note that the kernel rejects any remount request that includes the context
|
|
option, \fBeven\fP when unchanged from the current context.
|
|
|
|
.BR "Warning: the \fIcontext\fP value might contain commas" ,
|
|
in which case the value has to be properly quoted, otherwise
|
|
.BR mount (8)
|
|
will interpret the comma as a separator between mount options. Don't forget that
|
|
the shell strips off quotes and thus
|
|
.BR "double quoting is required" .
|
|
For example:
|
|
.RS
|
|
.RS
|
|
.sp
|
|
.nf
|
|
.B mount \-t tmpfs none /mnt \-o \e
|
|
.B \ \ 'context="system_u:object_r:tmp_t:s0:c127,c456",noexec'
|
|
.fi
|
|
.sp
|
|
.RE
|
|
For more details, see
|
|
.BR selinux (8).
|
|
.RE
|
|
|
|
.TP
|
|
.B defaults
|
|
Use the default options:
|
|
.BR rw ", " suid ", " dev ", " exec ", " auto ", " nouser ", and " async .
|
|
|
|
Note that the real set of all default mount options depends on kernel
|
|
and filesystem type. See the beginning of this section for more details.
|
|
.TP
|
|
.B dev
|
|
Interpret character or block special devices on the filesystem.
|
|
.TP
|
|
.B nodev
|
|
Do not interpret character or block special devices on the file
|
|
system.
|
|
.TP
|
|
.B diratime
|
|
Update directory inode access times on this filesystem. This is the default.
|
|
(This option is ignored when \fBnoatime\fR is set.)
|
|
.TP
|
|
.B nodiratime
|
|
Do not update directory inode access times on this filesystem.
|
|
(This option is implied when \fBnoatime\fR is set.)
|
|
.TP
|
|
.B dirsync
|
|
All directory updates within the filesystem should be done synchronously.
|
|
This affects the following system calls: creat, link, unlink, symlink,
|
|
mkdir, rmdir, mknod and rename.
|
|
.TP
|
|
.B exec
|
|
Permit execution of binaries.
|
|
.TP
|
|
.B noexec
|
|
Do not permit direct execution of any binaries on the mounted filesystem.
|
|
.TP
|
|
.B group
|
|
Allow an ordinary user to mount the filesystem if one
|
|
of that user's groups matches the group of the device.
|
|
This option implies the options
|
|
.BR nosuid " and " nodev
|
|
(unless overridden by subsequent options, as in the option line
|
|
.BR group,dev,suid ).
|
|
.TP
|
|
.B iversion
|
|
Every time the inode is modified, the i_version field will be incremented.
|
|
.TP
|
|
.B noiversion
|
|
Do not increment the i_version inode field.
|
|
.TP
|
|
.B mand
|
|
Allow mandatory locks on this filesystem. See
|
|
.BR fcntl (2).
|
|
.TP
|
|
.B nomand
|
|
Do not allow mandatory locks on this filesystem.
|
|
.TP
|
|
.B _netdev
|
|
The filesystem resides on a device that requires network access
|
|
(used to prevent the system from attempting to mount these filesystems
|
|
until the network has been enabled on the system).
|
|
.TP
|
|
.B nofail
|
|
Do not report errors for this device if it does not exist.
|
|
.TP
|
|
.B relatime
|
|
Update inode access times relative to modify or change time. Access
|
|
time is only updated if the previous access time was earlier than the
|
|
current modify or change time. (Similar to \fB\%noatime\fR, but it doesn't
|
|
break \fBmutt\fR or other applications that need to know if a file has been
|
|
read since the last time it was modified.)
|
|
|
|
Since Linux 2.6.30, the kernel defaults to the behavior provided by this
|
|
option (unless
|
|
.B \%noatime
|
|
was specified), and the
|
|
.B \%strictatime
|
|
option is required to obtain traditional semantics. In addition, since Linux
|
|
2.6.30, the file's last access time is always updated if it is more than 1
|
|
day old.
|
|
.TP
|
|
.B norelatime
|
|
Do not use the
|
|
.B relatime
|
|
feature. See also the
|
|
.B strictatime
|
|
mount option.
|
|
.TP
|
|
.B strictatime
|
|
Allows to explicitly request full atime updates. This makes it
|
|
possible for the kernel to default to
|
|
.B \%relatime
|
|
or
|
|
.B \%noatime
|
|
but still allow userspace to override it. For more details about the default
|
|
system mount options see /proc/mounts.
|
|
.TP
|
|
.B nostrictatime
|
|
Use the kernel's default behavior for inode access time updates.
|
|
.TP
|
|
.B lazytime
|
|
Only update times (atime, mtime, ctime) on the in-memory version of the file inode.
|
|
|
|
This mount option significantly reduces writes to the inode table for
|
|
workloads that perform frequent random writes to preallocated files.
|
|
|
|
The on-disk timestamps are updated only when:
|
|
.sp
|
|
.RS
|
|
- the inode needs to be updated for some change unrelated to file timestamps
|
|
.sp
|
|
- the application employs
|
|
.BR fsync (2),
|
|
.BR syncfs (2),
|
|
or
|
|
.BR sync (2)
|
|
.sp
|
|
- an undeleted inode is evicted from memory
|
|
.sp
|
|
- more than 24 hours have passed since the i-node was written to disk.
|
|
.RE
|
|
.sp
|
|
.TP
|
|
.B nolazytime
|
|
Do not use the lazytime feature.
|
|
.TP
|
|
.B suid
|
|
Honor set-user-ID and set-group-ID bits or file capabilities when
|
|
executing programs from this filesystem.
|
|
.TP
|
|
.B nosuid
|
|
Do not honor set-user-ID and set-group-ID bits or file capabilities when
|
|
executing programs from this filesystem.
|
|
.TP
|
|
.B silent
|
|
Turn on the silent flag.
|
|
.TP
|
|
.B loud
|
|
Turn off the silent flag.
|
|
.TP
|
|
.B owner
|
|
Allow an ordinary user to mount the filesystem if that
|
|
user is the owner of the device.
|
|
This option implies the options
|
|
.BR nosuid " and " nodev
|
|
(unless overridden by subsequent options, as in the option line
|
|
.BR owner,dev,suid ).
|
|
.TP
|
|
.B remount
|
|
Attempt to remount an already-mounted filesystem. This is commonly
|
|
used to change the mount flags for a filesystem, especially to make a
|
|
readonly filesystem writable. It does not change device or mount point.
|
|
|
|
The remount operation together with the
|
|
.B bind
|
|
flag has special semantic. See above, the subsection \fBBind mounts\fR.
|
|
|
|
The remount functionality follows the standard way the mount command works
|
|
with options from fstab. This means that \fBmount\fR does not
|
|
read fstab (or mtab) only when both
|
|
.I device
|
|
and
|
|
.I dir
|
|
are specified.
|
|
.sp
|
|
.in +4
|
|
.B "mount \-o remount,rw /dev/foo /dir"
|
|
.in
|
|
.sp
|
|
After this call all old mount options are replaced and arbitrary stuff from
|
|
fstab (or mtab) is ignored, except the loop= option which is internally
|
|
generated and maintained by the mount command.
|
|
.sp
|
|
.in +4
|
|
.B "mount \-o remount,rw /dir"
|
|
.in
|
|
.sp
|
|
After this call, mount reads fstab and merges these options with
|
|
the options from the command line (\fB\-o\fR).
|
|
If no mountpoint is found in fstab, then a remount with unspecified source is
|
|
allowed.
|
|
.sp
|
|
mount(8) allows to use \fB\-\-all\fR to remount all already mounted filesystems
|
|
which match a specified filter (\fB\-O\fR and \fB\-t\fR). For example:
|
|
.sp
|
|
.in +4
|
|
.B "mount \-\-all \-o remount,ro \-t vfat"
|
|
.in
|
|
.sp
|
|
remounts all already mounted vfat filesystems in read-only mode. The each of the
|
|
filesystems is remounted by "mount \-o remount,ro /dir" semantic. It means the
|
|
mount command reads fstab or mtab and merges these options with the options
|
|
from the command line.
|
|
.TP
|
|
.B ro
|
|
Mount the filesystem read-only.
|
|
.TP
|
|
.B rw
|
|
Mount the filesystem read-write.
|
|
.TP
|
|
.B sync
|
|
All I/O to the filesystem should be done synchronously. In the case of
|
|
media with a limited number of write cycles
|
|
(e.g.\& some flash drives), \fBsync\fR may cause life-cycle shortening.
|
|
.TP
|
|
.B user
|
|
Allow an ordinary user to mount the filesystem.
|
|
The name of the mounting user is written to the mtab file (or to the private
|
|
libmount file in /run/mount on systems without a regular mtab) so that this
|
|
same user can unmount the filesystem again.
|
|
This option implies the options
|
|
.BR noexec ", " nosuid ", and " nodev
|
|
(unless overridden by subsequent options, as in the option line
|
|
.BR user,exec,dev,suid ).
|
|
.TP
|
|
.B nouser
|
|
Forbid an ordinary user to mount the filesystem.
|
|
This is the default; it does not imply any other options.
|
|
.TP
|
|
.B users
|
|
Allow any user to mount and to unmount the filesystem, even
|
|
when some other ordinary user mounted it.
|
|
This option implies the options
|
|
.BR noexec ", " nosuid ", and " nodev
|
|
(unless overridden by subsequent options, as in the option line
|
|
.BR users,exec,dev,suid ).
|
|
.TP
|
|
.B X-*
|
|
All options prefixed with "X-" are interpreted as comments or as userspace
|
|
application-specific options. These options are not stored in the user space (e.g., mtab file),
|
|
nor sent to the mount.\fItype\fR helpers nor to the
|
|
.BR mount (2)
|
|
system call. The suggested format is \fBX-\fIappname\fR.\fIoption\fR.
|
|
.TP
|
|
.B x-*
|
|
The same as \fBX-*\fR options, but stored permanently in the user space. It
|
|
means the options are also available for umount or another operations. Note
|
|
that maintain mount options in user space is tricky, because it's necessary use
|
|
libmount based tools and there is no guarantee that the options will be always
|
|
available (for example after a move mount operation or in unshared namespace).
|
|
|
|
Note that before util-linux v2.30 the x-* options have not been maintained by
|
|
libmount and stored in user space (functionality was the same as have X-* now),
|
|
but due to growing number of use-cases (in initrd, systemd etc.) the
|
|
functionality have been extended to keep existing fstab configurations usable
|
|
without a change.
|
|
.TP
|
|
.BR X-mount.mkdir [ = \fImode\fR ]
|
|
Allow to make a target directory (mountpoint) if it does not exit yet.
|
|
The optional argument
|
|
.I mode
|
|
specifies the filesystem access mode used for
|
|
.BR mkdir (2)
|
|
in octal notation. The default mode is 0755. This functionality is supported
|
|
only for root users or when mount executed without suid permissions. The option
|
|
is also supported as x-mount.mkdir, this notation is deprecated since v2.30.
|
|
|
|
.SH "FILESYSTEM-SPECIFIC MOUNT OPTIONS"
|
|
You should consult the respective man page for the filesystem first.
|
|
If you want to know what options the ext4 filesystem supports, then check the
|
|
.BR ext4 (5)
|
|
man page.
|
|
If that doesn't exist, you can also check the corresponding mount page like
|
|
.BR mount.cifs (8).
|
|
Note that you might have to install the respective userland tools.
|
|
.sp
|
|
The following options apply only to certain filesystems.
|
|
We sort them by filesystem. They all follow the
|
|
.B \-o
|
|
flag.
|
|
.sp
|
|
What options are supported depends a bit on the running kernel.
|
|
More info may be found in the kernel source subdirectory
|
|
.IR Documentation/filesystems .
|
|
|
|
.SS "Mount options for adfs"
|
|
.TP
|
|
\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP
|
|
Set the owner and group of the files in the filesystem (default: uid=gid=0).
|
|
.TP
|
|
\fBownmask=\fP\,\fIvalue\fP and \fBothmask=\fP\,\fIvalue\fP
|
|
Set the permission mask for ADFS 'owner' permissions and 'other' permissions,
|
|
respectively (default: 0700 and 0077, respectively).
|
|
See also
|
|
.IR /usr/src/linux/Documentation/filesystems/adfs.txt .
|
|
|
|
.SS "Mount options for affs"
|
|
.TP
|
|
\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP
|
|
Set the owner and group of the root of the filesystem (default: uid=gid=0,
|
|
but with option
|
|
.B uid
|
|
or
|
|
.B gid
|
|
without specified value, the UID and GID of the current process are taken).
|
|
.TP
|
|
\fBsetuid=\fP\,\fIvalue\fP and \fBsetgid=\fP\,\fIvalue\fP
|
|
Set the owner and group of all files.
|
|
.TP
|
|
.BI mode= value
|
|
Set the mode of all files to
|
|
.IR value " & 0777"
|
|
disregarding the original permissions.
|
|
Add search permission to directories that have read permission.
|
|
The value is given in octal.
|
|
.TP
|
|
.B protect
|
|
Do not allow any changes to the protection bits on the filesystem.
|
|
.TP
|
|
.B usemp
|
|
Set UID and GID of the root of the filesystem to the UID and GID
|
|
of the mount point upon the first sync or umount, and then
|
|
clear this option. Strange...
|
|
.TP
|
|
.B verbose
|
|
Print an informational message for each successful mount.
|
|
.TP
|
|
.BI prefix= string
|
|
Prefix used before volume name, when following a link.
|
|
.TP
|
|
.BI volume= string
|
|
Prefix (of length at most 30) used before '/' when following a symbolic link.
|
|
.TP
|
|
.BI reserved= value
|
|
(Default: 2.) Number of unused blocks at the start of the device.
|
|
.TP
|
|
.BI root= value
|
|
Give explicitly the location of the root block.
|
|
.TP
|
|
.BI bs= value
|
|
Give blocksize. Allowed values are 512, 1024, 2048, 4096.
|
|
.TP
|
|
.BR grpquota | noquota | quota | usrquota
|
|
These options are accepted but ignored.
|
|
(However, quota utilities may react to such strings in
|
|
.IR /etc/fstab .)
|
|
|
|
.SS "Mount options for debugfs"
|
|
The debugfs filesystem is a pseudo filesystem, traditionally mounted on
|
|
.IR /sys/kernel/debug .
|
|
.\" or just /debug
|
|
.\" present since 2.6.11
|
|
As of kernel version 3.4, debugfs has the following options:
|
|
.TP
|
|
.BI uid= n ", gid=" n
|
|
Set the owner and group of the mountpoint.
|
|
.TP
|
|
.BI mode= value
|
|
Sets the mode of the mountpoint.
|
|
|
|
.SS "Mount options for devpts"
|
|
The devpts filesystem is a pseudo filesystem, traditionally mounted on
|
|
.IR /dev/pts .
|
|
In order to acquire a pseudo terminal, a process opens
|
|
.IR /dev/ptmx ;
|
|
the number of the pseudo terminal is then made available to the process
|
|
and the pseudo terminal slave can be accessed as
|
|
.IR /dev/pts/ <number>.
|
|
.TP
|
|
\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP
|
|
This sets the owner or the group of newly created PTYs to
|
|
the specified values. When nothing is specified, they will
|
|
be set to the UID and GID of the creating process.
|
|
For example, if there is a tty group with GID 5, then
|
|
.B gid=5
|
|
will cause newly created PTYs to belong to the tty group.
|
|
.TP
|
|
.BI mode= value
|
|
Set the mode of newly created PTYs to the specified value.
|
|
The default is 0600.
|
|
A value of
|
|
.B mode=620
|
|
and
|
|
.B gid=5
|
|
makes "mesg y" the default on newly created PTYs.
|
|
.TP
|
|
\fBnewinstance
|
|
Create a private instance of devpts filesystem, such that
|
|
indices of ptys allocated in this new instance are
|
|
independent of indices created in other instances of devpts.
|
|
|
|
All mounts of devpts without this
|
|
.B newinstance
|
|
option share the same set of pty indices (i.e., legacy mode).
|
|
Each mount of devpts with the
|
|
.B newinstance
|
|
option has a private set of pty indices.
|
|
|
|
This option is mainly used to support containers in the
|
|
linux kernel. It is implemented in linux kernel versions
|
|
starting with 2.6.29. Further, this mount option is valid
|
|
only if CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the
|
|
kernel configuration.
|
|
|
|
To use this option effectively,
|
|
.I /dev/ptmx
|
|
must be a symbolic link to
|
|
.I pts/ptmx.
|
|
See
|
|
.I Documentation/filesystems/devpts.txt
|
|
in the linux kernel source tree for details.
|
|
.TP
|
|
.BI ptmxmode= value
|
|
|
|
Set the mode for the new
|
|
.I ptmx
|
|
device node in the devpts filesystem.
|
|
|
|
With the support for multiple instances of devpts (see
|
|
.B newinstance
|
|
option above), each instance has a private
|
|
.I ptmx
|
|
node in the root of the devpts filesystem (typically
|
|
.IR /dev/pts/ptmx ).
|
|
|
|
For compatibility with older versions of the kernel, the
|
|
default mode of the new
|
|
.I ptmx
|
|
node is 0000.
|
|
.BI ptmxmode= value
|
|
specifies a more useful mode for the
|
|
.I ptmx
|
|
node and is highly recommended when the
|
|
.B newinstance
|
|
option is specified.
|
|
|
|
This option is only implemented in linux kernel versions
|
|
starting with 2.6.29. Further, this option is valid only if
|
|
CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the kernel
|
|
configuration.
|
|
|
|
.SS "Mount options for fat"
|
|
(Note:
|
|
.I fat
|
|
is not a separate filesystem, but a common part of the
|
|
.IR msdos ,
|
|
.I umsdos
|
|
and
|
|
.I vfat
|
|
filesystems.)
|
|
.TP
|
|
.BR blocksize= { 512 | 1024 | 2048 }
|
|
Set blocksize (default 512). This option is obsolete.
|
|
.TP
|
|
\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP
|
|
Set the owner and group of all files.
|
|
(Default: the UID and GID of the current process.)
|
|
.TP
|
|
.BI umask= value
|
|
Set the umask (the bitmask of the permissions that are
|
|
.B not
|
|
present). The default is the umask of the current process.
|
|
The value is given in octal.
|
|
.TP
|
|
.BI dmask= value
|
|
Set the umask applied to directories only.
|
|
The default is the umask of the current process.
|
|
The value is given in octal.
|
|
.TP
|
|
.BI fmask= value
|
|
Set the umask applied to regular files only.
|
|
The default is the umask of the current process.
|
|
The value is given in octal.
|
|
.TP
|
|
.BI allow_utime= value
|
|
This option controls the permission check of mtime/atime.
|
|
.RS
|
|
.TP
|
|
.B 20
|
|
If current process is in group of file's group ID, you can change timestamp.
|
|
.TP
|
|
.B 2
|
|
Other users can change timestamp.
|
|
.PP
|
|
The default is set from `dmask' option. (If the directory is writable,
|
|
.BR utime (2)
|
|
is also allowed. I.e.\& \s+3~\s0dmask & 022)
|
|
|
|
Normally
|
|
.BR utime (2)
|
|
checks current process is owner of the file, or it has
|
|
CAP_FOWNER capability. But FAT filesystem doesn't have UID/GID on disk, so
|
|
normal check is too inflexible. With this option you can relax it.
|
|
.RE
|
|
.TP
|
|
.BI check= value
|
|
Three different levels of pickiness can be chosen:
|
|
.RS
|
|
.TP
|
|
.BR r [ elaxed ]
|
|
Upper and lower case are accepted and equivalent, long name parts are
|
|
truncated (e.g.\&
|
|
.I verylongname.foobar
|
|
becomes
|
|
.IR verylong.foo ),
|
|
leading and embedded spaces are accepted in each name part (name and extension).
|
|
.TP
|
|
.BR n [ ormal ]
|
|
Like "relaxed", but many special characters (*, ?, <, spaces, etc.) are
|
|
rejected. This is the default.
|
|
.TP
|
|
.BR s [ trict ]
|
|
Like "normal", but names that contain long parts or special characters
|
|
that are sometimes used on Linux but are not accepted by MS-DOS
|
|
(+, =, etc.) are rejected.
|
|
.RE
|
|
.TP
|
|
.BI codepage= value
|
|
Sets the codepage for converting to shortname characters on FAT
|
|
and VFAT filesystems. By default, codepage 437 is used.
|
|
.TP
|
|
.BI conv= mode
|
|
This option is obsolete and may fail or being ignored.
|
|
.TP
|
|
.BI cvf_format= module
|
|
Forces the driver to use the CVF (Compressed Volume File) module
|
|
.RI cvf_ module
|
|
instead of auto-detection. If the kernel supports kmod, the
|
|
cvf_format=xxx option also controls on-demand CVF module loading.
|
|
This option is obsolete.
|
|
.TP
|
|
.BI cvf_option= option
|
|
Option passed to the CVF module. This option is obsolete.
|
|
.TP
|
|
.B debug
|
|
Turn on the
|
|
.I debug
|
|
flag. A version string and a list of filesystem parameters will be
|
|
printed (these data are also printed if the parameters appear to be
|
|
inconsistent).
|
|
.TP
|
|
.B discard
|
|
If set, causes discard/TRIM commands to be issued to the block device
|
|
when blocks are freed. This is useful for SSD devices and
|
|
sparse/thinly-provisioned LUNs.
|
|
.TP
|
|
.B dos1xfloppy
|
|
If set, use a fallback default BIOS Parameter Block configuration, determined
|
|
by backing device size. These static parameters match defaults assumed by DOS
|
|
1.x for 160 kiB, 180 kiB, 320 kiB, and 360 kiB floppies and floppy images.
|
|
.TP
|
|
.BR errors= { panic | continue | remount-ro }
|
|
Specify FAT behavior on critical errors: panic, continue without doing
|
|
anything, or remount the partition in read-only mode (default behavior).
|
|
.TP
|
|
.BR fat= { 12 | 16 | 32 }
|
|
Specify a 12, 16 or 32 bit fat. This overrides
|
|
the automatic FAT type detection routine. Use with caution!
|
|
.TP
|
|
.BI iocharset= value
|
|
Character set to use for converting between 8 bit characters
|
|
and 16 bit Unicode characters. The default is iso8859-1.
|
|
Long filenames are stored on disk in Unicode format.
|
|
.TP
|
|
.BR nfs= { stale_rw | nostale_ro }
|
|
Enable this only if you want to export the FAT filesystem over NFS.
|
|
|
|
.BR stale_rw :
|
|
This option maintains an index (cache) of directory inodes which is used by the
|
|
nfs-related code to improve look-ups. Full file operations (read/write) over
|
|
NFS are supported but with cache eviction at NFS server, this could result in
|
|
spurious
|
|
.B ESTALE
|
|
errors.
|
|
|
|
.BR nostale_ro :
|
|
This option bases the inode number and file handle
|
|
on the on-disk location of a file in the FAT directory entry.
|
|
This ensures that
|
|
.B ESTALE
|
|
will not be returned after a file is
|
|
evicted from the inode cache. However, it means that operations
|
|
such as rename, create and unlink could cause file handles that
|
|
previously pointed at one file to point at a different file,
|
|
potentially causing data corruption. For this reason, this
|
|
option also mounts the filesystem readonly.
|
|
|
|
To maintain backward compatibility, '\-o nfs' is also accepted,
|
|
defaulting to
|
|
.BR stale_rw .
|
|
.TP
|
|
.B tz=UTC
|
|
This option disables the conversion of timestamps
|
|
between local time (as used by Windows on FAT) and UTC
|
|
(which Linux uses internally). This is particularly
|
|
useful when mounting devices (like digital cameras)
|
|
that are set to UTC in order to avoid the pitfalls of
|
|
local time.
|
|
.TP
|
|
.BI time_offset= minutes
|
|
Set offset for conversion of timestamps from local time used by FAT to UTC.
|
|
I.e.,
|
|
.I minutes
|
|
will be subtracted from each timestamp to convert it to UTC used
|
|
internally by Linux. This is useful when the time zone set in the kernel via
|
|
.BR settimeofday (2)
|
|
is not the time zone used by the filesystem. Note
|
|
that this option still does not provide correct time stamps in all cases in
|
|
presence of DST - time stamps in a different DST setting will be off by one
|
|
hour.
|
|
.TP
|
|
.B quiet
|
|
Turn on the
|
|
.I quiet
|
|
flag. Attempts to chown or chmod files do not return errors,
|
|
although they fail. Use with caution!
|
|
.TP
|
|
.B rodir
|
|
FAT has the ATTR_RO (read-only) attribute. On Windows, the ATTR_RO of the
|
|
directory will just be ignored, and is used only by applications as a flag
|
|
(e.g.\& it's set for the customized folder).
|
|
|
|
If you want to use ATTR_RO as read-only flag even for the directory, set this
|
|
option.
|
|
.TP
|
|
.B showexec
|
|
If set, the execute permission bits of the file will be allowed only if
|
|
the extension part of the name is \&.EXE, \&.COM, or \&.BAT. Not set by default.
|
|
.TP
|
|
.B sys_immutable
|
|
If set, ATTR_SYS attribute on FAT is handled as IMMUTABLE flag on Linux.
|
|
Not set by default.
|
|
.TP
|
|
.B flush
|
|
If set, the filesystem will try to flush to disk more early than normal.
|
|
Not set by default.
|
|
.TP
|
|
.B usefree
|
|
Use the "free clusters" value stored on FSINFO. It'll
|
|
be used to determine number of free clusters without
|
|
scanning disk. But it's not used by default, because
|
|
recent Windows don't update it correctly in some
|
|
case. If you are sure the "free clusters" on FSINFO is
|
|
correct, by this option you can avoid scanning disk.
|
|
.TP
|
|
.BR dots ", " nodots ", " dotsOK= [ yes | no ]
|
|
Various misguided attempts to force Unix or DOS conventions
|
|
onto a FAT filesystem.
|
|
|
|
.SS "Mount options for hfs"
|
|
.TP
|
|
.BI creator= cccc ", type=" cccc
|
|
Set the creator/type values as shown by the MacOS finder
|
|
used for creating new files. Default values: '????'.
|
|
.TP
|
|
.BI uid= n ", gid=" n
|
|
Set the owner and group of all files.
|
|
(Default: the UID and GID of the current process.)
|
|
.TP
|
|
.BI dir_umask= n ", file_umask=" n ", umask=" n
|
|
Set the umask used for all directories, all regular files, or all
|
|
files and directories. Defaults to the umask of the current process.
|
|
.TP
|
|
.BI session= n
|
|
Select the CDROM session to mount.
|
|
Defaults to leaving that decision to the CDROM driver.
|
|
This option will fail with anything but a CDROM as underlying device.
|
|
.TP
|
|
.BI part= n
|
|
Select partition number n from the device.
|
|
Only makes sense for CDROMs.
|
|
Defaults to not parsing the partition table at all.
|
|
.TP
|
|
.B quiet
|
|
Don't complain about invalid mount options.
|
|
|
|
.SS "Mount options for hpfs"
|
|
.TP
|
|
\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP
|
|
Set the owner and group of all files. (Default: the UID and GID
|
|
of the current process.)
|
|
.TP
|
|
.BI umask= value
|
|
Set the umask (the bitmask of the permissions that are
|
|
.B not
|
|
present). The default is the umask of the current process.
|
|
The value is given in octal.
|
|
.TP
|
|
.BR case= { lower | asis }
|
|
Convert all files names to lower case, or leave them.
|
|
(Default:
|
|
.BR case=lower .)
|
|
.TP
|
|
.BI conv= mode
|
|
This option is obsolete and may fail or being ignored.
|
|
.TP
|
|
.B nocheck
|
|
Do not abort mounting when certain consistency checks fail.
|
|
|
|
.SS "Mount options for iso9660"
|
|
ISO 9660 is a standard describing a filesystem structure to be used
|
|
on CD-ROMs. (This filesystem type is also seen on some DVDs. See also the
|
|
.I udf
|
|
filesystem.)
|
|
|
|
Normal
|
|
.I iso9660
|
|
filenames appear in an 8.3 format (i.e., DOS-like restrictions on filename
|
|
length), and in addition all characters are in upper case. Also there is
|
|
no field for file ownership, protection, number of links, provision for
|
|
block/character devices, etc.
|
|
|
|
Rock Ridge is an extension to iso9660 that provides all of these UNIX-like
|
|
features. Basically there are extensions to each directory record that
|
|
supply all of the additional information, and when Rock Ridge is in use,
|
|
the filesystem is indistinguishable from a normal UNIX filesystem (except
|
|
that it is read-only, of course).
|
|
.TP
|
|
.B norock
|
|
Disable the use of Rock Ridge extensions, even if available. Cf.\&
|
|
.BR map .
|
|
.TP
|
|
.B nojoliet
|
|
Disable the use of Microsoft Joliet extensions, even if available. Cf.\&
|
|
.BR map .
|
|
.TP
|
|
.BR check= { r [ elaxed ]| s [ trict ]}
|
|
With
|
|
.BR check=relaxed ,
|
|
a filename is first converted to lower case before doing the lookup.
|
|
This is probably only meaningful together with
|
|
.B norock
|
|
and
|
|
.BR map=normal .
|
|
(Default:
|
|
.BR check=strict .)
|
|
.TP
|
|
\fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP
|
|
Give all files in the filesystem the indicated user or group id,
|
|
possibly overriding the information found in the Rock Ridge extensions.
|
|
(Default:
|
|
.BR uid=0,gid=0 .)
|
|
.TP
|
|
.BR map= { n [ ormal ]| o [ ff ]| a [ corn ]}
|
|
For non-Rock Ridge volumes, normal name translation maps upper
|
|
to lower case ASCII, drops a trailing `;1', and converts `;' to `.'.
|
|
With
|
|
.B map=off
|
|
no name translation is done. See
|
|
.BR norock .
|
|
(Default:
|
|
.BR map=normal .)
|
|
.B map=acorn
|
|
is like
|
|
.B map=normal
|
|
but also apply Acorn extensions if present.
|
|
.TP
|
|
.BI mode= value
|
|
For non-Rock Ridge volumes, give all files the indicated mode.
|
|
(Default: read and execute permission for everybody.)
|
|
Octal mode values require a leading 0.
|
|
.TP
|
|
.B unhide
|
|
Also show hidden and associated files.
|
|
(If the ordinary files and the associated or hidden files have
|
|
the same filenames, this may make the ordinary files inaccessible.)
|
|
.TP
|
|
.BR block= { 512 | 1024 | 2048 }
|
|
Set the block size to the indicated value.
|
|
(Default:
|
|
.BR block=1024 .)
|
|
.TP
|
|
.BI conv= mode
|
|
This option is obsolete and may fail or being ignored.
|
|
.TP
|
|
.B cruft
|
|
If the high byte of the file length contains other garbage,
|
|
set this mount option to ignore the high order bits of the file length.
|
|
This implies that a file cannot be larger than 16\ MB.
|
|
.TP
|
|
.BI session= x
|
|
Select number of session on multisession CD.
|
|
.TP
|
|
.BI sbsector= xxx
|
|
Session begins from sector xxx.
|
|
.LP
|
|
The following options are the same as for vfat and specifying them only makes
|
|
sense when using discs encoded using Microsoft's Joliet extensions.
|
|
.TP
|
|
.BI iocharset= value
|
|
Character set to use for converting 16 bit Unicode characters on CD
|
|
to 8 bit characters. The default is iso8859-1.
|
|
.TP
|
|
.B utf8
|
|
Convert 16 bit Unicode characters on CD to UTF-8.
|
|
|
|
.SS "Mount options for jfs"
|
|
.TP
|
|
.BI iocharset= name
|
|
Character set to use for converting from Unicode to ASCII. The default is
|
|
to do no conversion. Use
|
|
.B iocharset=utf8
|
|
for UTF8 translations. This requires CONFIG_NLS_UTF8 to be set in
|
|
the kernel
|
|
.I ".config"
|
|
file.
|
|
.TP
|
|
.BI resize= value
|
|
Resize the volume to
|
|
.I value
|
|
blocks. JFS only supports growing a volume, not shrinking it. This option
|
|
is only valid during a remount, when the volume is mounted read-write. The
|
|
.B resize
|
|
keyword with no value will grow the volume to the full size of the partition.
|
|
.TP
|
|
.B nointegrity
|
|
Do not write to the journal. The primary use of this option is to allow
|
|
for higher performance when restoring a volume from backup media. The
|
|
integrity of the volume is not guaranteed if the system abnormally ends.
|
|
.TP
|
|
.B integrity
|
|
Default. Commit metadata changes to the journal. Use this option to remount
|
|
a volume where the
|
|
.B nointegrity
|
|
option was previously specified in order to restore normal behavior.
|
|
.TP
|
|
.BR errors= { continue | remount-ro | panic }
|
|
Define the behavior when an error is encountered.
|
|
(Either ignore errors and just mark the filesystem erroneous and continue,
|
|
or remount the filesystem read-only, or panic and halt the system.)
|
|
.TP
|
|
.BR noquota | quota | usrquota | grpquota
|
|
These options are accepted but ignored.
|
|
|
|
.SS "Mount options for msdos"
|
|
See mount options for fat.
|
|
If the
|
|
.I msdos
|
|
filesystem detects an inconsistency, it reports an error and sets the file
|
|
system read-only. The filesystem can be made writable again by remounting
|
|
it.
|
|
|
|
.SS "Mount options for ncpfs"
|
|
Just like
|
|
.IR nfs ", the " ncpfs
|
|
implementation expects a binary argument (a
|
|
.IR "struct ncp_mount_data" )
|
|
to the mount system call. This argument is constructed by
|
|
.BR ncpmount (8)
|
|
and the current version of
|
|
.B mount
|
|
(2.12) does not know anything about ncpfs.
|
|
|
|
.SS "Mount options for ntfs"
|
|
.TP
|
|
.BI iocharset= name
|
|
Character set to use when returning file names.
|
|
Unlike VFAT, NTFS suppresses names that contain
|
|
nonconvertible characters. Deprecated.
|
|
.TP
|
|
.BI nls= name
|
|
New name for the option earlier called
|
|
.IR iocharset .
|
|
.TP
|
|
.B utf8
|
|
Use UTF-8 for converting file names.
|
|
.TP
|
|
.BR uni_xlate= { 0 | 1 | 2 }
|
|
For 0 (or `no' or `false'), do not use escape sequences
|
|
for unknown Unicode characters.
|
|
For 1 (or `yes' or `true') or 2, use vfat-style 4-byte escape sequences
|
|
starting with ":". Here 2 give a little-endian encoding
|
|
and 1 a byteswapped bigendian encoding.
|
|
.TP
|
|
.B posix=[0|1]
|
|
If enabled (posix=1), the filesystem distinguishes between
|
|
upper and lower case. The 8.3 alias names are presented as
|
|
hard links instead of being suppressed. This option is obsolete.
|
|
.TP
|
|
\fBuid=\fP\,\fIvalue\fP, \fBgid=\fP\,\fIvalue\fP and \fBumask=\fP\,\fIvalue\fP
|
|
Set the file permission on the filesystem.
|
|
The umask value is given in octal.
|
|
By default, the files are owned by root and not readable by somebody else.
|
|
|
|
.SS "Mount options for overlay"
|
|
Since Linux 3.18 the overlay pseudo filesystem implements a union mount for
|
|
other filesystems.
|
|
|
|
An overlay filesystem combines two filesystems - an \fBupper\fR filesystem and
|
|
a \fBlower\fR filesystem. When a name exists in both filesystems, the object
|
|
in the upper filesystem is visible while the object in the lower filesystem is
|
|
either hidden or, in the case of directories, merged with the upper object.
|
|
|
|
The lower filesystem can be any filesystem supported by Linux and does not need
|
|
to be writable. The lower filesystem can even be another overlayfs. The upper
|
|
filesystem will normally be writable and if it is it must support the creation
|
|
of trusted.* extended attributes, and must provide a valid d_type in readdir
|
|
responses, so NFS is not suitable.
|
|
|
|
A read-only overlay of two read-only filesystems may use any filesystem type.
|
|
The options \fBlowerdir\fR and \fBupperdir\fR are combined into a merged
|
|
directory by using:
|
|
|
|
.RS
|
|
.br
|
|
.nf
|
|
.B "mount \-t overlay overlay \e"
|
|
.B " \-olowerdir=/lower,upperdir=/upper,workdir=/work /merged"
|
|
.fi
|
|
.br
|
|
.RE
|
|
|
|
.TP
|
|
.BI lowerdir= directory
|
|
Any filesystem, does not need to be on a writable filesystem.
|
|
.TP
|
|
.BI upperdir= directory
|
|
The upperdir is normally on a writable filesystem.
|
|
.TP
|
|
.BI workdir= directory
|
|
The workdir needs to be an empty directory on the same filesystem as upperdir.
|
|
|
|
.SS "Mount options for reiserfs"
|
|
Reiserfs is a journaling filesystem.
|
|
.TP
|
|
.B conv
|
|
Instructs version 3.6 reiserfs software to mount a version 3.5 filesystem,
|
|
using the 3.6 format for newly created objects. This filesystem will no
|
|
longer be compatible with reiserfs 3.5 tools.
|
|
.TP
|
|
.BR hash= { rupasov | tea | r5 | detect }
|
|
Choose which hash function reiserfs will use to find files within directories.
|
|
.RS
|
|
.TP
|
|
.B rupasov
|
|
A hash invented by Yury Yu.\& Rupasov. It is fast and preserves locality,
|
|
mapping lexicographically close file names to close hash values.
|
|
This option should not be used, as it causes a high probability of hash
|
|
collisions.
|
|
.TP
|
|
.B tea
|
|
A Davis-Meyer function implemented by Jeremy Fitzhardinge.
|
|
It uses hash permuting bits in the name. It gets high randomness
|
|
and, therefore, low probability of hash collisions at some CPU cost.
|
|
This may be used if EHASHCOLLISION errors are experienced with the r5 hash.
|
|
.TP
|
|
.B r5
|
|
A modified version of the rupasov hash. It is used by default and is
|
|
the best choice unless the filesystem has huge directories and
|
|
unusual file-name patterns.
|
|
.TP
|
|
.B detect
|
|
Instructs
|
|
.I mount
|
|
to detect which hash function is in use by examining
|
|
the filesystem being mounted, and to write this information into
|
|
the reiserfs superblock. This is only useful on the first mount of
|
|
an old format filesystem.
|
|
.RE
|
|
.TP
|
|
.B hashed_relocation
|
|
Tunes the block allocator. This may provide performance improvements
|
|
in some situations.
|
|
.TP
|
|
.B no_unhashed_relocation
|
|
Tunes the block allocator. This may provide performance improvements
|
|
in some situations.
|
|
.TP
|
|
.B noborder
|
|
Disable the border allocator algorithm invented by Yury Yu.\& Rupasov.
|
|
This may provide performance improvements in some situations.
|
|
.TP
|
|
.B nolog
|
|
Disable journaling. This will provide slight performance improvements in
|
|
some situations at the cost of losing reiserfs's fast recovery from crashes.
|
|
Even with this option turned on, reiserfs still performs all journaling
|
|
operations, save for actual writes into its journaling area. Implementation
|
|
of
|
|
.I nolog
|
|
is a work in progress.
|
|
.TP
|
|
.B notail
|
|
By default, reiserfs stores small files and `file tails' directly into its
|
|
tree. This confuses some utilities such as
|
|
.BR LILO (8).
|
|
This option is used to disable packing of files into the tree.
|
|
.TP
|
|
.B replayonly
|
|
Replay the transactions which are in the journal, but do not actually
|
|
mount the filesystem. Mainly used by
|
|
.IR reiserfsck .
|
|
.TP
|
|
.BI resize= number
|
|
A remount option which permits online expansion of reiserfs partitions.
|
|
Instructs reiserfs to assume that the device has
|
|
.I number
|
|
blocks.
|
|
This option is designed for use with devices which are under logical
|
|
volume management (LVM).
|
|
There is a special
|
|
.I resizer
|
|
utility which can be obtained from
|
|
.IR ftp://ftp.namesys.com/pub/reiserfsprogs .
|
|
.TP
|
|
.B user_xattr
|
|
Enable Extended User Attributes. See the
|
|
.BR attr (1)
|
|
manual page.
|
|
.TP
|
|
.B acl
|
|
Enable POSIX Access Control Lists. See the
|
|
.BR acl (5)
|
|
manual page.
|
|
.TP
|
|
.BR barrier=none " / " barrier=flush "
|
|
This disables / enables the use of write barriers in the journaling code.
|
|
barrier=none disables, barrier=flush enables (default). This also requires an
|
|
IO stack which can support barriers, and if reiserfs gets an error on a barrier
|
|
write, it will disable barriers again with a warning. Write barriers enforce
|
|
proper on-disk ordering of journal commits, making volatile disk write caches
|
|
safe to use, at some performance penalty. If your disks are battery-backed in
|
|
one way or another, disabling barriers may safely improve performance.
|
|
|
|
.SS "Mount options for ubifs"
|
|
UBIFS is a flash filesystem which works on top of UBI volumes. Note that
|
|
\fBatime\fR is not supported and is always turned off.
|
|
.TP
|
|
The device name may be specified as
|
|
.RS
|
|
.B ubiX_Y
|
|
UBI device number
|
|
.BR X ,
|
|
volume number
|
|
.B Y
|
|
.TP
|
|
.B ubiY
|
|
UBI device number
|
|
.BR 0 ,
|
|
volume number
|
|
.B Y
|
|
.TP
|
|
.B ubiX:NAME
|
|
UBI device number
|
|
.BR X ,
|
|
volume with name
|
|
.B NAME
|
|
.TP
|
|
.B ubi:NAME
|
|
UBI device number
|
|
.BR 0 ,
|
|
volume with name
|
|
.B NAME
|
|
.RE
|
|
Alternative
|
|
.B !
|
|
separator may be used instead of
|
|
.BR : .
|
|
.TP
|
|
The following mount options are available:
|
|
.TP
|
|
.B bulk_read
|
|
Enable bulk-read. VFS read-ahead is disabled because it slows down the file
|
|
system. Bulk-Read is an internal optimization. Some flashes may read faster if
|
|
the data are read at one go, rather than at several read requests. For
|
|
example, OneNAND can do "read-while-load" if it reads more than one NAND page.
|
|
.TP
|
|
.B no_bulk_read
|
|
Do not bulk-read. This is the default.
|
|
.TP
|
|
.B chk_data_crc
|
|
Check data CRC-32 checksums. This is the default.
|
|
.TP
|
|
.BR no_chk_data_crc .
|
|
Do not check data CRC-32 checksums. With this option, the filesystem does not
|
|
check CRC-32 checksum for data, but it does check it for the internal indexing
|
|
information. This option only affects reading, not writing. CRC-32 is always
|
|
calculated when writing the data.
|
|
.TP
|
|
.BR compr= { none | lzo | zlib }
|
|
Select the default compressor which is used when new files are written. It is
|
|
still possible to read compressed files if mounted with the
|
|
.B none
|
|
option.
|
|
|
|
.SS "Mount options for udf"
|
|
UDF is the "Universal Disk Format" filesystem defined by OSTA, the Optical
|
|
Storage Technology Association, and is often used for DVD-ROM, frequently
|
|
in the form of a hybrid UDF/ISO-9660 filesystem. It is, however,
|
|
perfectly usable by itself on disk drives, flash drives and other block devices.
|
|
See also
|
|
.IR iso9660 .
|
|
.TP
|
|
.B uid=
|
|
Make all files in the filesystem belong to the given user.
|
|
uid=forget can be specified independently of (or usually in
|
|
addition to) uid=<user> and results in UDF
|
|
not storing uids to the media. In fact the recorded uid
|
|
is the 32-bit overflow uid \-1 as defined by the UDF standard.
|
|
The value is given as either <user> which is a valid user name or the corresponding
|
|
decimal user id, or the special string "forget".
|
|
.TP
|
|
.B gid=
|
|
Make all files in the filesystem belong to the given group.
|
|
gid=forget can be specified independently of (or usually in
|
|
addition to) gid=<group> and results in UDF
|
|
not storing gids to the media. In fact the recorded gid
|
|
is the 32-bit overflow gid \-1 as defined by the UDF standard.
|
|
The value is given as either <group> which is a valid group name or the corresponding
|
|
decimal group id, or the special string "forget".
|
|
.TP
|
|
.B umask=
|
|
Mask out the given permissions from all inodes read from the filesystem.
|
|
The value is given in octal.
|
|
.TP
|
|
.B mode=
|
|
If mode= is set the permissions of all non-directory inodes read from the
|
|
filesystem will be set to the given mode. The value is given in octal.
|
|
.TP
|
|
.B dmode=
|
|
If dmode= is set the permissions of all directory inodes read from the
|
|
filesystem will be set to the given dmode. The value is given in octal.
|
|
.TP
|
|
.B bs=
|
|
Set the block size. Default value prior to kernel version 2.6.30 was
|
|
2048. Since 2.6.30 and prior to 4.11 it was logical device block size with
|
|
fallback to 2048. Since 4.11 it is logical block size with fallback to
|
|
any valid block size between logical device block size and 4096.
|
|
|
|
For other details see the \fBmkudffs\fP(8) 2.0+ manpage, sections
|
|
\fBCOMPATIBILITY\fP and \fBBLOCK SIZE\fP.
|
|
.TP
|
|
.B unhide
|
|
Show otherwise hidden files.
|
|
.TP
|
|
.B undelete
|
|
Show deleted files in lists.
|
|
.TP
|
|
.B adinicb
|
|
Embed data in the inode. (default)
|
|
.TP
|
|
.B noadinicb
|
|
Don't embed data in the inode.
|
|
.TP
|
|
.B shortad
|
|
Use short UDF address descriptors.
|
|
.TP
|
|
.B longad
|
|
Use long UDF address descriptors. (default)
|
|
.TP
|
|
.B nostrict
|
|
Unset strict conformance.
|
|
.TP
|
|
.B iocharset=
|
|
Set the NLS character set. This requires kernel compiled with CONFIG_UDF_NLS option.
|
|
.TP
|
|
.B utf8
|
|
Set the UTF-8 character set.
|
|
.SS Mount options for debugging and disaster recovery
|
|
.TP
|
|
.B novrs
|
|
Ignore the Volume Recognition Sequence and attempt to mount anyway.
|
|
.TP
|
|
.B session=
|
|
Select the session number for multi-session recorded optical media. (default= last session)
|
|
.TP
|
|
.B anchor=
|
|
Override standard anchor location. (default= 256)
|
|
.TP
|
|
.B lastblock=
|
|
Set the last block of the filesystem.
|
|
.SS Unused historical mount options that may be encountered and should be removed
|
|
.TP
|
|
.B uid=ignore
|
|
Ignored, use uid=<user> instead.
|
|
.TP
|
|
.B gid=ignore
|
|
Ignored, use gid=<group> instead.
|
|
.TP
|
|
.B volume=
|
|
Unimplemented and ignored.
|
|
.TP
|
|
.B partition=
|
|
Unimplemented and ignored.
|
|
.TP
|
|
.B fileset=
|
|
Unimplemented and ignored.
|
|
.TP
|
|
.B rootdir=
|
|
Unimplemented and ignored.
|
|
|
|
.SS "Mount options for ufs"
|
|
.TP
|
|
.BI ufstype= value
|
|
UFS is a filesystem widely used in different operating systems.
|
|
The problem are differences among implementations. Features of some
|
|
implementations are undocumented, so its hard to recognize the
|
|
type of ufs automatically.
|
|
That's why the user must specify the type of ufs by mount option.
|
|
Possible values are:
|
|
.RS
|
|
.TP
|
|
.B old
|
|
Old format of ufs, this is the default, read only.
|
|
(Don't forget to give the \-r option.)
|
|
.TP
|
|
.B 44bsd
|
|
For filesystems created by a BSD-like system (NetBSD, FreeBSD, OpenBSD).
|
|
.TP
|
|
.B ufs2
|
|
Used in FreeBSD 5.x supported as read-write.
|
|
.TP
|
|
.B 5xbsd
|
|
Synonym for ufs2.
|
|
.TP
|
|
.B sun
|
|
For filesystems created by SunOS or Solaris on Sparc.
|
|
.TP
|
|
.B sunx86
|
|
For filesystems created by Solaris on x86.
|
|
.TP
|
|
.B hp
|
|
For filesystems created by HP-UX, read-only.
|
|
.TP
|
|
.B nextstep
|
|
For filesystems created by NeXTStep (on NeXT station) (currently read only).
|
|
.TP
|
|
.B nextstep-cd
|
|
For NextStep CDROMs (block_size == 2048), read-only.
|
|
.TP
|
|
.B openstep
|
|
For filesystems created by OpenStep (currently read only).
|
|
The same filesystem type is also used by Mac OS X.
|
|
.RE
|
|
|
|
.TP
|
|
.BI onerror= value
|
|
Set behavior on error:
|
|
.RS
|
|
.TP
|
|
.B panic
|
|
If an error is encountered, cause a kernel panic.
|
|
.TP
|
|
.RB [ lock | umount | repair ]
|
|
These mount options don't do anything at present;
|
|
when an error is encountered only a console message is printed.
|
|
.RE
|
|
|
|
.SS "Mount options for umsdos"
|
|
See mount options for msdos.
|
|
The
|
|
.B dotsOK
|
|
option is explicitly killed by
|
|
.IR umsdos .
|
|
|
|
.SS "Mount options for vfat"
|
|
First of all, the mount options for
|
|
.I fat
|
|
are recognized.
|
|
The
|
|
.B dotsOK
|
|
option is explicitly killed by
|
|
.IR vfat .
|
|
Furthermore, there are
|
|
.TP
|
|
.B uni_xlate
|
|
Translate unhandled Unicode characters to special escaped sequences.
|
|
This lets you backup and restore filenames that are created with any
|
|
Unicode characters. Without this option, a '?' is used when no
|
|
translation is possible. The escape character is ':' because it is
|
|
otherwise invalid on the vfat filesystem. The escape sequence
|
|
that gets used, where u is the Unicode character,
|
|
is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).
|
|
.TP
|
|
.B posix
|
|
Allow two files with names that only differ in case.
|
|
This option is obsolete.
|
|
.TP
|
|
.B nonumtail
|
|
First try to make a short name without sequence number,
|
|
before trying
|
|
.IR name\s+3~\s0num.ext .
|
|
.TP
|
|
.B utf8
|
|
UTF8 is the filesystem safe 8-bit encoding of Unicode that is used by the
|
|
console. It can be enabled for the filesystem with this option or disabled
|
|
with utf8=0, utf8=no or utf8=false. If `uni_xlate' gets set, UTF8 gets
|
|
disabled.
|
|
.TP
|
|
.BI shortname= mode
|
|
Defines the behavior for creation and display of filenames which fit into
|
|
8.3 characters. If a long name for a file exists, it will always be the
|
|
preferred one for display. There are four \fImode\fRs:
|
|
.RS
|
|
.TP
|
|
.B lower
|
|
Force the short name to lower case upon display; store a long name when
|
|
the short name is not all upper case.
|
|
.TP
|
|
.B win95
|
|
Force the short name to upper case upon display; store a long name when
|
|
the short name is not all upper case.
|
|
.TP
|
|
.B winnt
|
|
Display the short name as is; store a long name when the short name is
|
|
not all lower case or all upper case.
|
|
.TP
|
|
.B mixed
|
|
Display the short name as is; store a long name when the short name is not
|
|
all upper case. This mode is the default since Linux 2.6.32.
|
|
.RE
|
|
|
|
.SS "Mount options for usbfs"
|
|
.TP
|
|
\fBdevuid=\fP\,\fIuid\fP and \fBdevgid=\fP\,\fIgid\fP and \fBdevmode=\fP\,\fImode\fP
|
|
Set the owner and group and mode of the device files in the usbfs filesystem
|
|
(default: uid=gid=0, mode=0644). The mode is given in octal.
|
|
.TP
|
|
\fBbusuid=\fP\,\fIuid\fP and \fBbusgid=\fP\,\fIgid\fP and \fBbusmode=\fP\,\fImode\fP
|
|
Set the owner and group and mode of the bus directories in the usbfs
|
|
filesystem (default: uid=gid=0, mode=0555). The mode is given in octal.
|
|
.TP
|
|
\fBlistuid=\fP\,\fIuid\fP and \fBlistgid=\fP\,\fIgid\fP and \fBlistmode=\fP\,\fImode\fP
|
|
Set the owner and group and mode of the file
|
|
.I devices
|
|
(default: uid=gid=0, mode=0444). The mode is given in octal.
|
|
|
|
.SH "DM-VERITY SUPPORT (experimental)"
|
|
The device-mapper verity target provides read-only transparent integrity
|
|
checking of block devices using kernel crypto API. The mount command can open
|
|
the dm-verity device and do the integrity verification before on the device
|
|
filesystem is mounted. Requires libcryptsetup with in libmount. If
|
|
libcryptsetup supports extracting the root hash of an already mounted device,
|
|
existing devices will be automatically reused in case of a match.
|
|
Mount options for dm-verity:
|
|
.TP
|
|
\fBverity.hashdevice=\fP\,\fIpath\fP
|
|
Path to the hash tree device associated with the source volume to pass to dm-verity.
|
|
.TP
|
|
\fBverity.roothash=\fP\,\fIhex\fP
|
|
Hex-encoded hash of the root of
|
|
.I verity.hashdevice
|
|
Mutually exclusive with
|
|
.I verity.roothashfile.
|
|
.TP
|
|
\fBverity.roothashfile=\fP\,\fIpath\fP
|
|
Path to file containing the hex-encoded hash of the root of
|
|
.I verity.hashdevice.
|
|
Mutually exclusive with
|
|
.I verity.roothash.
|
|
.TP
|
|
\fBverity.hashoffset=\fP\,\fIoffset\fP
|
|
If the hash tree device is embedded in the source volume,
|
|
.I offset
|
|
(default: 0) is used by dm-verity to get to the tree.
|
|
.TP
|
|
\fBverity.fecdevice=\fP\,\fIpath\fP
|
|
Path to the Forward Error Correction (FEC) device associated with the source volume to pass to dm-verity.
|
|
Optional. Requires kernel built with CONFIG_DM_VERITY_FEC.
|
|
.TP
|
|
\fBverity.fecoffset=\fP\,\fIoffset\fP
|
|
If the FEC device is embedded in the source volume,
|
|
.I offset
|
|
(default: 0) is used by dm-verity to get to the FEC area. Optional.
|
|
.TP
|
|
\fBverity.fecroots=\fP\,\fIvalue\fP
|
|
Parity bytes for FEC (default: 2). Optional.
|
|
.TP
|
|
\fBverity.roothashsig=\fP\,\fIpath\fP
|
|
Path to pkcs7 signature of root hash hex string. Requires crypt_activate_by_signed_key() from cryptsetup and
|
|
kernel built with CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG. For device reuse, signatures have to be either used by all
|
|
mounts of a device or by none. Optional.
|
|
.RE
|
|
.PP
|
|
Supported since util-linux v2.35.
|
|
.PP
|
|
For example commands:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
.B mksquashfs /etc /tmp/etc.squashfs
|
|
.B dd if=/dev/zero of=/tmp/etc.hash bs=1M count=10
|
|
.B veritysetup format /tmp/etc.squashfs /tmp/etc.hash
|
|
.B openssl smime \-sign \-in <hash> \-nocerts \-inkey private.key \-signer private.crt \-noattr \-binary \-outform der \-out /tmp/etc.p7
|
|
.B mount \-o verity.hashdevice=/tmp/etc.hash,verity.roothash=<hash>,verity.roothashsig=/tmp/etc.p7 /tmp/etc.squashfs /mnt
|
|
.fi
|
|
.RE
|
|
.sp
|
|
create squashfs image from /etc directory, verity hash device
|
|
and mount verified filesystem image to /mnt.
|
|
The kernel will verify that the root hash is signed by a key from the kernel keyring if roothashsig is used.
|
|
|
|
.SH "LOOP-DEVICE SUPPORT"
|
|
One further possible type is a mount via the loop device. For example,
|
|
the command
|
|
.RS
|
|
.sp
|
|
.B "mount /tmp/disk.img /mnt \-t vfat \-o loop=/dev/loop3"
|
|
.sp
|
|
.RE
|
|
will set up the loop device
|
|
.I /dev/loop3
|
|
to correspond to the file
|
|
.IR /tmp/disk.img ,
|
|
and then mount this device on
|
|
.IR /mnt .
|
|
|
|
If no explicit loop device is mentioned
|
|
(but just an option `\fB\-o loop\fP' is given), then
|
|
.B mount
|
|
will try to find some unused loop device and use that, for example
|
|
.RS
|
|
.sp
|
|
.B "mount /tmp/disk.img /mnt \-o loop"
|
|
.sp
|
|
.RE
|
|
The mount command
|
|
.B automatically
|
|
creates a loop device from a regular file if a filesystem type is
|
|
not specified or the filesystem is known for libblkid, for example:
|
|
.RS
|
|
.sp
|
|
.B "mount /tmp/disk.img /mnt"
|
|
.sp
|
|
.B "mount \-t ext4 /tmp/disk.img /mnt"
|
|
.sp
|
|
.RE
|
|
This type of mount knows about three options, namely
|
|
.BR loop ", " offset " and " sizelimit ,
|
|
that are really options to
|
|
.BR \%losetup (8).
|
|
(These options can be used in addition to those specific
|
|
to the filesystem type.)
|
|
|
|
Since Linux 2.6.25 auto-destruction of loop devices is supported,
|
|
meaning that any loop device allocated by
|
|
.B mount
|
|
will be freed by
|
|
.B umount
|
|
independently of
|
|
.IR /etc/mtab .
|
|
|
|
You can also free a loop device by hand, using
|
|
.BR "losetup \-d " or " umount \-d" .
|
|
|
|
Since util-linux v2.29 mount command re-uses the loop device rather than
|
|
initialize a new device if the same backing file is already used for some loop
|
|
device with the same offset and sizelimit. This is necessary to avoid
|
|
a filesystem corruption.
|
|
|
|
.SH RETURN CODES
|
|
.B mount
|
|
has the following return codes (the bits can be ORed):
|
|
.TP
|
|
.B 0
|
|
success
|
|
.TP
|
|
.B 1
|
|
incorrect invocation or permissions
|
|
.TP
|
|
.B 2
|
|
system error (out of memory, cannot fork, no more loop devices)
|
|
.TP
|
|
.B 4
|
|
internal
|
|
.B mount
|
|
bug
|
|
.TP
|
|
.B 8
|
|
user interrupt
|
|
.TP
|
|
.B 16
|
|
problems writing or locking /etc/mtab
|
|
.TP
|
|
.B 32
|
|
mount failure
|
|
.TP
|
|
.B 64
|
|
some mount succeeded
|
|
|
|
The command \fBmount \-a\fR returns 0 (all succeeded), 32 (all failed), or 64 (some
|
|
failed, some succeeded).
|
|
|
|
.SH "EXTERNAL HELPERS"
|
|
The syntax of external mount helpers is:
|
|
.sp
|
|
.in +4
|
|
.BI /sbin/mount. suffix
|
|
.I spec dir
|
|
.RB [ \-sfnv ]
|
|
.RB [ \-N
|
|
.IR namespace ]
|
|
.RB [ \-o
|
|
.IR options ]
|
|
.RB [ \-t
|
|
.IR type \fB. subtype ]
|
|
.in
|
|
.sp
|
|
where the \fIsuffix\fR is the filesystem type and the \fB\-sfnvoN\fR options have
|
|
the same meaning as the normal mount options. The \fB\-t\fR option is used for
|
|
filesystems with subtypes support (for example
|
|
.BR "/sbin/mount.fuse \-t fuse.sshfs" ).
|
|
|
|
The command \fBmount\fR does not pass the mount options
|
|
.BR unbindable ,
|
|
.BR runbindable ,
|
|
.BR private ,
|
|
.BR rprivate ,
|
|
.BR slave ,
|
|
.BR rslave ,
|
|
.BR shared ,
|
|
.BR rshared ,
|
|
.BR auto ,
|
|
.BR noauto ,
|
|
.BR comment ,
|
|
.BR x-* ,
|
|
.BR loop ,
|
|
.B offset
|
|
and
|
|
.B sizelimit
|
|
to the mount.<suffix> helpers. All other options are used in a
|
|
comma-separated list as argument to the \fB\-o\fR option.
|
|
|
|
.SH FILES
|
|
See also "\fBThe files /etc/fstab, /etc/mtab and /proc/mounts\fR" section above.
|
|
.TP 18n
|
|
.I /etc/fstab
|
|
filesystem table
|
|
.TP
|
|
.I /run/mount
|
|
libmount private runtime directory
|
|
.TP
|
|
.I /etc/mtab
|
|
table of mounted filesystems or symlink to /proc/mounts
|
|
.TP
|
|
.I /etc/mtab\s+3~\s0
|
|
lock file (unused on systems with mtab symlink)
|
|
.TP
|
|
.I /etc/mtab.tmp
|
|
temporary file (unused on systems with mtab symlink)
|
|
.TP
|
|
.I /etc/filesystems
|
|
a list of filesystem types to try
|
|
.SH ENVIRONMENT
|
|
.IP LIBMOUNT_FSTAB=<path>
|
|
overrides the default location of the fstab file (ignored for suid)
|
|
.IP LIBMOUNT_MTAB=<path>
|
|
overrides the default location of the mtab file (ignored for suid)
|
|
.IP LIBMOUNT_DEBUG=all
|
|
enables libmount debug output
|
|
.IP LIBBLKID_DEBUG=all
|
|
enables libblkid debug output
|
|
.IP LOOPDEV_DEBUG=all
|
|
enables loop device setup debug output
|
|
.SH "SEE ALSO"
|
|
.na
|
|
.BR mount (2),
|
|
.BR umount (2),
|
|
.BR umount (8),
|
|
.BR fstab (5),
|
|
.BR nfs (5),
|
|
.BR xfs (5),
|
|
.BR e2label (8),
|
|
.BR findmnt (8),
|
|
.BR losetup (8),
|
|
.BR mke2fs (8),
|
|
.BR mountd (8),
|
|
.BR nfsd (8),
|
|
.BR swapon (8),
|
|
.BR tune2fs (8),
|
|
.BR xfs_admin (8)
|
|
.ad
|
|
.SH BUGS
|
|
It is possible for a corrupted filesystem to cause a crash.
|
|
.PP
|
|
Some Linux filesystems don't support
|
|
.BR "\-o sync " nor " \-o dirsync"
|
|
(the ext2, ext3, ext4, fat and vfat filesystems
|
|
.I do
|
|
support synchronous updates (a la BSD) when mounted with the
|
|
.B sync
|
|
option).
|
|
.PP
|
|
The
|
|
.B "\-o remount"
|
|
may not be able to change mount parameters (all
|
|
.IR ext2fs -specific
|
|
parameters, except
|
|
.BR sb ,
|
|
are changeable with a remount, for example, but you can't change
|
|
.B gid
|
|
or
|
|
.B umask
|
|
for the
|
|
.IR fatfs ).
|
|
.PP
|
|
It is possible that the files
|
|
.I /etc/mtab
|
|
and
|
|
.I /proc/mounts
|
|
don't match on systems with a regular mtab file. The first file is based only on
|
|
the mount command options, but the content of the second file also depends on
|
|
the kernel and others settings (e.g.\& on a remote NFS server -- in certain cases
|
|
the mount command may report unreliable information about an NFS mount point
|
|
and the /proc/mounts file usually contains more reliable information.) This is
|
|
another reason to replace the mtab file with a symlink to the
|
|
.I /proc/mounts
|
|
file.
|
|
.PP
|
|
Checking files on NFS filesystems referenced by file descriptors (i.e.\& the
|
|
.B fcntl
|
|
and
|
|
.B ioctl
|
|
families of functions) may lead to inconsistent results due to the lack of
|
|
a consistency check in the kernel even if noac is used.
|
|
.PP
|
|
The
|
|
.B loop
|
|
option with the
|
|
.B offset
|
|
or
|
|
.B sizelimit
|
|
options used may fail when using older kernels if the
|
|
.B mount
|
|
command can't confirm that the size of the block device has been configured
|
|
as requested. This situation can be worked around by using
|
|
the
|
|
.B losetup
|
|
command manually before calling
|
|
.B mount
|
|
with the configured loop device.
|
|
.SH HISTORY
|
|
A
|
|
.B mount
|
|
command existed in Version 5 AT&T UNIX.
|
|
.SH AUTHORS
|
|
.nf
|
|
Karel Zak <kzak@redhat.com>
|
|
.fi
|
|
.SH AVAILABILITY
|
|
The mount command is part of the util-linux package and is available from
|
|
https://www.kernel.org/pub/linux/utils/util-linux/.
|