NAME
mount - mount a filesystemSYNOPSIS
mount [-h|-V]DESCRIPTION
All files accessible in a Unix system are arranged in one big tree, the file hierarchy, rooted at /. These files can be spread out over several devices. The mount command serves to attach the filesystem found on some device to the big file tree. Conversely, the umount(8) command will detach it again. The filesystem is used to control how data is stored on the device or provided in a virtual way by network or other services.Listing the mounts
The listing mode is maintained for backward compatibility only.Indicating the device and filesystem
Most devices are indicated by a filename (of a block special device), like /dev/sda1, but there are other possibilities. For example, in the case of an NFS mount, device may look like knuth.cwi.nl:/dir.Human readable filesystem identifier. See also
-L.
Filesystem universally unique identifier. The
format of the UUID is usually a series of hex digits separated by hyphens. See
also -U.
Note that mount uses UUIDs as strings. The UUIDs from the command line or
from fstab(5) are not converted to internal binary representation. The
string representation of the UUID should be based on lower case
characters.
Human readable partition identifier. This
identifier is independent on filesystem and does not change by mkfs or
mkswap operations. It’s supported for example for GUID Partition
Tables (GPT).
Partition universally unique identifier. This
identifier is independent on filesystem and does not change by mkfs or
mkswap operations. It’s supported for example for GUID Partition
Tables (GPT).
Hardware block device ID as generated by
udevd. This identifier is usually based on WWN (unique storage identifier) and
assigned by the hardware manufacturer. See ls /dev/disk/by-id for more
details, this directory and running udevd is required. This identifier is not
recommended for generic use as the identifier is not strictly defined and it
depends on udev, udev rules and hardware.
The files /etc/fstab, /etc/mtab and /proc/mounts
The file /etc/fstab (see fstab(5)), may contain lines describing what devices are usually mounted where, using which options. The default location of the fstab(5) file can be overridden with the --fstab path command-line option (see below for more details).Non-superuser mounts
Normally, only the superuser can mount filesystems. However, when fstab contains the user option on a line, anybody can mount the corresponding filesystem.Bind mount operation
Remount part of the file hierarchy somewhere else. The call is:The move operation
Move a mounted tree to another place (atomically). The call is: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 Documentation/filesystems/sharedsubtree.txt file in the kernel source tree; see also mount_namespaces(7).mount --make-shared mountpoint mount --make-slave mountpoint mount --make-private mountpoint mount --make-unbindable mountpoint
mount --make-rshared mountpoint mount --make-rslave mountpoint mount --make-rprivate mountpoint mount --make-runbindable mountpoint
mount --make-private --make-unbindable /dev/sda1 /foo
mount /dev/sda1 /foo mount --make-private /foo mount --make-unbindable /foo
COMMAND-LINE OPTIONS
The full set of mount options used by an invocation of mount is determined by first extracting the mount options for the filesystem from the fstab table, then applying any options specified by the -o argument, and finally applying a -r or -w option, when present.Mount all filesystems (of the given types)
mentioned in fstab (except for those whose line contains the
noauto keyword). The filesystems are mounted following their order in
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 mount
--all. This means that all duplicated fstab entries will be
mounted.
The correct functionality depends on /proc (to detect already mounted
filesystems) and on /sys (to evaluate filesystem tags like UUID= or
LABEL=). It’s strongly recommended to mount /proc and
/sys filesystems before mount -a is executed, or keep /proc and
/sys at the beginning of fstab.
The option --all is possible to use for remount operation too. In this
case all filters ( -t and -O) are applied to the table of
already mounted filesystems.
Since version 2.35 it is possible to use the command line option -o to
alter mount options from fstab (see also --options-mode).
Note that it is a bad practice to use mount -a for fstab checking.
The recommended solution is findmnt --verify.
Remount a subtree somewhere else (so that its
contents are available in both places). See above, under Bind
mounts.
Don’t canonicalize paths. The
mount command canonicalizes all paths (from the command line or
fstab) by default. This option can be used together with the -f
flag for already canonicalized absolute paths. The option is designed for
mount helpers which call mount -i. It is strongly recommended to not
use this command-line option for normal mount operations.
Note that mount does not pass this option to the
/sbin/mount.type helpers.
(Used in conjunction with -a.) Fork off
a new incarnation of mount 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 proceed in parallel. A disadvantage is
that the order of the mount operations is undefined. Thus, you cannot use this
option if you want to mount both /usr and /usr/spool.
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
-v flag to determine what the mount command is trying to do. It
can also be used to add entries for devices that were mounted earlier with the
-n option. The -f 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).
Don’t call the
/sbin/mount.filesystem helper even if it exists.
Mount the partition that has the specified
label.
Add the labels in the mount output.
mount 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 e2label(8) utility, or for XFS using xfs_admin(8), or for
reiserfs using reiserfstune(8).
Move a subtree to some other place. See above,
the subsection The move operation.
Allow to make a target directory (mountpoint)
if it does not exist yet. Alias to "-o X-mount.mkdir[=mode]", the
default mode is 0755. For more details see X-mount.mkdir below.
Mount without writing in /etc/mtab.
This is necessary for example when /etc is on a read-only
filesystem.
Perform the mount operation in the mount
namespace specified by ns. ns is either PID of process running
in that namespace or special file representing that namespace.
mount switches to the mount namespace when it reads /etc/fstab,
writes /etc/mtab: (or writes to _/run/mount) and calls mount(2),
otherwise it runs in the original mount namespace. This means that the target
namespace does not have to contain any libraries or other requirements
necessary to execute the mount(2) call.
See mount_namespaces(7) for more information.
Limit the set of filesystems to which the
-a option applies. In this regard it is like the -t option
except that -O is useless without -a. For example, the command
mount -a -O no_netdev
mounts all filesystems except those which have the option netdev
specified in the options field in the /etc/fstab file.
It is different from -t in that each option is matched exactly; a leading
no at the beginning of one option does not negate the rest.
The -t and -O options are cumulative in effect; that is, the
command
mount -a -t ext2 -O _netdev
mounts all ext2 filesystems with the _netdev option, not all filesystems that
are either ext2 or have the _netdev option specified.
Use the specified mount options. The
opts argument is a comma-separated list. For example:
mount LABEL=mydisk -o noatime,nodev,nosuid
For more details, see the FILESYSTEM-INDEPENDENT MOUNT OPTIONS and
FILESYSTEM-SPECIFIC MOUNT OPTIONS sections.
Controls how to combine options from
fstab/ mtab with options from the command line. mode can
be one of ignore, append, prepend or replace. For
example, append means that options from fstab are appended to
options from the command line. The default value is prepend — it
means command line options are evaluated after fstab options. Note that
the last option wins if there are conflicting ones.
Source of default options. source is a
comma-separated list of fstab, mtab and disable.
disable disables fstab and mtab and enables
--options-source-force. The default value is fstab,mtab.
Use options from fstab/mtab even
if both device and dir are specified.
Remount a subtree and all possible submounts
somewhere else (so that its contents are available in both places). See above,
the subsection Bind mounts.
Mount the filesystem read-only. A synonym is
-o ro.
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 ro,noload
mount options or set the block device itself to read-only mode, see the
blockdev(8) command.
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 mount.nfs mount helper only.
If only one argument for the mount
command is given, then the argument might be interpreted as the target
(mountpoint) or source (device). This option allows you to explicitly define
that the argument is the mount source.
If only one argument for the mount command is
given, then the argument might be interpreted as the target (mountpoint) or
source (device). This option allows you to explicitly define that the argument
is the mount target.
Prepend the specified directory to all mount
targets. This option can be used to follow fstab, but mount operations
are done in another place, for example:
mount --all --target-prefix /chroot -o X-mount.mkdir
mounts all from system fstab to /chroot, all missing mountpoint
are created (due to X-mount.mkdir). See also --fstab to use an
alternative fstab.
Specifies an alternative fstab file. If
path is a directory, then the files in the directory are sorted by
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.
Note that mount does not pass the option --fstab to the
/sbin/mount. type 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.
The argument following the -t is used
to indicate the filesystem type. The filesystem types which are currently
supported depend on the running kernel. See /proc/filesystems and
/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.
The programs mount and umount(8) 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 -t option is given, or if the auto type is specified,
mount will try to guess the desired type. mount uses the
libblkid(3) library for guessing the filesystem type; if that does not
turn up anything that looks familiar, mount will try to read the file
/etc/filesystems, or, if that does not exist, /proc/filesystems.
All of the filesystem types listed there will be tried, except for those that
are labeled "nodev" (e.g. devpts, proc and
nfs). If /etc/filesystems ends in a line with a single *, mount
will read /proc/filesystems afterwards. While trying, all filesystem
types will be mounted with the mount option silent.
The auto type may be useful for user-mounted floppies. Creating a file
/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.
More than one type may be specified in a comma-separated list, for the -t
option as well as in an /etc/fstab entry. The list of filesystem types
for the -t option can be prefixed with no to specify the
filesystem types on which no action should be taken. The prefix no has
no effect when specified in an /etc/fstab entry.
The prefix no can be meaningful with the -a option. For example,
the command
mount -a -t nomsdos,smbfs
mounts all filesystems except those of type msdos and smbfs.
For most types all the mount program has to do is issue a simple
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, mount will execute the program
/sbin/mount.type (if that exists) when called with type
type. Since different versions of the smbmount program have
different calling conventions, /sbin/mount.smbfs may have to be a shell
script that sets up the desired call.
Mount the partition that has the specified
uuid.
Verbose mode.
Mount the filesystem read/write. Read-write is
the kernel default and the mount default is to try read-only if the
previous mount(2) syscall with read-write flags on write-protected
devices failed.
A synonym is -o rw.
Note that specifying -w on the command line forces mount to never
try read-only mount on write-protected devices or already mounted read-only
filesystems.
Display help text and exit.
Print version and exit.
FILESYSTEM-INDEPENDENT MOUNT OPTIONS
Some of these options are only useful when they appear in the /etc/fstab file.All I/O to the filesystem should be done
asynchronously. (See also the sync option.)
Do not use the noatime feature, so the
inode access time is controlled by kernel defaults. See also the descriptions
of the relatime and strictatime mount options.
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
nodiratime.
Can be mounted with the -a
option.
Can only be mounted explicitly (i.e., the
-a option will not cause the filesystem to be mounted).
The 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 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
context="system_u:object_r:removable_t.
The 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
defcontext= option. This overrides the value set for unlabeled files in
the policy and requires a filesystem that supports xattr labeling.
The 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, even when unchanged from the current context.
Warning: the context value might contain commas, in which
case the value has to be properly quoted, otherwise mount will
interpret the comma as a separator between mount options. Don’t forget
that the shell strips off quotes and thus double quoting is required.
For example:
Use the default options: rw,
suid, dev, exec, auto, nouser, and
async.
Note that the real set of all default mount options depends on the kernel and
filesystem type. See the beginning of this section for more details.
Interpret character or block special devices
on the filesystem.
Do not interpret character or block special
devices on the filesystem.
Update directory inode access times on this
filesystem. This is the default. (This option is ignored when noatime
is set.)
Do not update directory inode access times on
this filesystem. (This option is implied when noatime is set.)
All directory updates within the filesystem
should be done synchronously. This affects the following system calls:
creat(2), link(2), unlink(2), symlink(2),
mkdir(2), rmdir(2), mknod(2) and rename(2).
Permit execution of binaries and other
executable files.
Do not permit direct execution of any binaries
on the mounted filesystem.
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 nosuid and nodev (unless overridden
by subsequent options, as in the option line group,dev,suid).
Every time the inode is modified, the
i_version field will be incremented.
Do not increment the i_version inode
field.
Allow mandatory locks on this filesystem. See
fcntl(2). This option was deprecated in Linux 5.15.
Do not allow mandatory locks on this
filesystem.
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).
Do not report errors for this device if it
does not exist.
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 noatime,
but it doesn’t break mutt(1) 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 noatime was specified), and the 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.
Do not use the relatime feature. See
also the strictatime mount option.
Allows to explicitly request full atime
updates. This makes it possible for the kernel to default to relatime
or noatime but still allow userspace to override it. For more details
about the default system mount options see /proc/mounts.
Use the kernel’s default behavior for
inode access time updates.
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:
•the inode needs to be updated for some
change unrelated to file timestamps
•an undeleted inode is evicted from
memory
•more than 24 hours have passed since
the inode was written to disk.
Do not use the lazytime feature.
Honor set-user-ID and set-group-ID bits or
file capabilities when executing programs from this filesystem.
Do not honor set-user-ID and set-group-ID bits
or file capabilities when executing programs from this filesystem. In
addition, SELinux domain transitions require permission
nosuid_transition, which in turn needs also policy capability
nnp_nosuid_transition.
Turn on the silent flag.
Turn off the silent flag.
Allow an ordinary user to mount the filesystem
if that user is the owner of the device. This option implies the options
nosuid and nodev (unless overridden by subsequent options, as in
the option line owner,dev,suid).
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 bind flag has special semantics.
See above, the subsection Bind mounts.
The remount functionality follows the standard way the mount command
works with options from fstab. This means that mount does not
read fstab (or mtab) only when both device and dir
are specified.
mount -o remount,rw /dev/foo /dir
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.
mount -o remount,rw /dir
After this call, mount reads fstab and merges these options with
the options from the command line ( -o). If no mountpoint is found in
fstab, then a remount with unspecified source is allowed.
mount allows the use of --all to remount all already mounted
filesystems which match a specified filter ( -O and -t). For
example:
mount --all -o remount,ro -t vfat
remounts all already mounted vfat filesystems in read-only mode. Each of the
filesystems is remounted by mount -o remount,ro /dir semantic.
This means the mount command reads fstab or mtab and
merges these options with the options from the command line.
Mount the filesystem read-only.
Mount the filesystem read-write.
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), sync may cause life-cycle shortening.
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 noexec, nosuid, and nodev
(unless overridden by subsequent options, as in the option line
user,exec,dev,suid).
Forbid an ordinary user to mount the
filesystem. This is the default; it does not imply any other options.
Allow any user to mount and to unmount the
filesystem, even when some other ordinary user mounted it. This option implies
the options noexec, nosuid, and nodev (unless overridden
by subsequent options, as in the option line
users,exec,dev,suid).
All options prefixed with "X-" are
interpreted as comments or as userspace application-specific options. These
options are not stored in user space (e.g., mtab file), nor sent to the
mount. type helpers nor to the mount(2) system call. The
suggested format is X-appname.option.
The same as X-* options, but stored
permanently in user space. This means the options are also available for
umount(8) or other operations. Note that maintaining 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 for X-* now),
but due to the growing number of use-cases (in initrd, systemd etc.) the
functionality has been extended to keep existing fstab configurations
usable without a change.
Allow to make a target directory (mountpoint)
if it does not exist yet. The optional argument mode specifies the
filesystem access mode used for mkdir(2) in octal notation. The default
mode is 0755. This functionality is supported only for root users or when
mount is executed without suid permissions. The option is also
supported as x-mount.mkdir, but this notation is deprecated since
v2.30. See also --mkdir command line option.
Allow mounting sub-directory from a filesystem
instead of the root directory. For now, this feature is implemented by
temporary filesystem root directory mount in unshared namespace and then bind
the sub-directory to the final mount point and umount the root of the
filesystem. The sub-directory mount shows up atomically for the rest of the
system although it is implemented by multiple mount(2) syscalls. This
feature is EXPERIMENTAL.
Do not follow symlinks when resolving paths.
Symlinks can still be created, and readlink(1), readlink(2),
realpath(1), and realpath(3) all still work properly.
FILESYSTEM-SPECIFIC MOUNT OPTIONS
This section lists options that are specific to particular filesystems. Where possible, you should first consult filesystem-specific manual pages for details. Some of those pages are listed in the following table.Filesystem(s) | Manual page |
btrfs | btrfs(5) |
cifs | mount.cifs(8) |
ext2, ext3, ext4 | ext4(5) |
fuse | fuse(8) |
nfs | nfs(5) |
tmpfs | tmpfs(5) |
xfs | xfs(5) |
Mount options for adfs
uid=value and gid=valueSet the owner and group of the files in the
filesystem (default: uid=gid=0).
Set the permission mask for ADFS 'owner'
permissions and 'other' permissions, respectively (default: 0700 and 0077,
respectively). See also
/usr/src/linux/Documentation/filesystems/adfs.rst.
Mount options for affs
uid=value and gid=valueSet the owner and group of the root of the
filesystem (default: uid=gid=0, but with option uid or gid
without specified value, the UID and GID of the current process are
taken).
Set the owner and group of all files.
Set the mode of all files to value
& 0777 disregarding the original permissions. Add search permission to
directories that have read permission. The value is given in octal.
Do not allow any changes to the protection
bits on the filesystem.
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...
Print an informational message for each
successful mount.
Prefix used before volume name, when following
a link.
Prefix (of length at most 30) used before '/'
when following a symbolic link.
(Default: 2.) Number of unused blocks at the
start of the device.
Give explicitly the location of the root
block.
Give blocksize. Allowed values are 512, 1024,
2048, 4096.
These options are accepted but ignored.
(However, quota utilities may react to such strings in
/etc/fstab.)
Mount options for debugfs
The debugfs filesystem is a pseudo filesystem, traditionally mounted on /sys/kernel/debug. As of kernel version 3.4, debugfs has the following options:Set the owner and group of the
mountpoint.
Sets the mode of the mountpoint.
Mount options for devpts
The devpts filesystem is a pseudo filesystem, traditionally mounted on /dev/pts. In order to acquire a pseudo terminal, a process opens /dev/ptmx; the number of the pseudo terminal is then made available to the process and the pseudo terminal slave can be accessed as /dev/pts/<number>.This sets the owner or the group of newly
created pseudo terminals 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 gid=5 will cause newly created
pseudo terminals to belong to the tty group.
Set the mode of newly created pseudo terminals
to the specified value. The default is 0600. A value of mode=620 and
gid=5 makes "mesg y" the default on newly created pseudo
terminals.
Create a private instance of the devpts
filesystem, such that indices of pseudo terminals allocated in this new
instance are independent of indices created in other instances of devpts.
All mounts of devpts without this newinstance option share the same set
of pseudo terminal indices (i.e., legacy mode). Each mount of devpts with the
newinstance option has a private set of pseudo terminal 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, /dev/ptmx must be a symbolic link to
pts/ptmx. See Documentation/filesystems/devpts.txt in the Linux
kernel source tree for details.
Set the mode for the new ptmx device
node in the devpts filesystem.
With the support for multiple instances of devpts (see newinstance option
above), each instance has a private ptmx node in the root of the devpts
filesystem (typically /dev/pts/ptmx).
For compatibility with older versions of the kernel, the default mode of the new
ptmx node is 0000. ptmxmode=value specifies a more useful
mode for the ptmx node and is highly recommended when the
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.
Mount options for fat
(Note: fat is not a separate filesystem, but a common part of the msdos, umsdos and vfat filesystems.)Set blocksize (default 512). This option is
obsolete.
Set the owner and group of all files.
(Default: the UID and GID of the current process.)
Set the umask (the bitmask of the permissions
that are not present). The default is the umask of the current process.
The value is given in octal.
Set the umask applied to directories only. The
default is the umask of the current process. The value is given in
octal.
Set the umask applied to regular files only.
The default is the umask of the current process. The value is given in
octal.
This option controls the permission check of
mtime/atime.
20
2
If current process is in group of
file’s group ID, you can change timestamp.
Other users can change timestamp.
Three different levels of pickiness can be
chosen:
r[elaxed]
n[ormal]
s[trict]
Upper and lower case are accepted and
equivalent, long name parts are truncated (e.g. verylongname.foobar
becomes verylong.foo), leading and embedded spaces are accepted in each
name part (name and extension).
Like "relaxed", but many special
characters (*, ?, <, spaces, etc.) are rejected. This is the default.
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.
Sets the codepage for converting to shortname
characters on FAT and VFAT filesystems. By default, codepage 437 is
used.
This option is obsolete and may fail or be
ignored.
Forces the driver to use the CVF (Compressed
Volume File) module 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.
Option passed to the CVF module. This option
is obsolete.
Turn on the 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).
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.
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.
Specify FAT behavior on critical errors:
panic, continue without doing anything, or remount the partition in read-only
mode (default behavior).
Specify a 12, 16 or 32 bit fat. This overrides
the automatic FAT type detection routine. Use with caution!
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.
Enable this only if you want to export the FAT
filesystem over NFS.
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 ESTALE errors.
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
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 stale_rw.
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.
Set offset for conversion of timestamps from
local time used by FAT to UTC. I.e., 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 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.
Turn on the quiet flag. Attempts to
chown or chmod files do not return errors, although they fail. Use with
caution!
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.
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.
If set, ATTR_SYS attribute on FAT is
handled as IMMUTABLE flag on Linux. Not set by default.
If set, the filesystem will try to flush to
disk more early than normal. Not set by default.
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.
Various misguided attempts to force Unix or
DOS conventions onto a FAT filesystem.
Mount options for hfs
creator=cccc, type=ccccSet the creator/type values as shown by the
MacOS finder used for creating new files. Default values: '????'.
Set the owner and group of all files.
(Default: the UID and GID of the current process.)
Set the umask used for all directories, all
regular files, or all files and directories. Defaults to the umask of the
current process.
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.
Select partition number n from the device.
Only makes sense for CDROMs. Defaults to not parsing the partition table at
all.
Don’t complain about invalid mount
options.
Mount options for hpfs
uid=value and gid=valueSet the owner and group of all files.
(Default: the UID and GID of the current process.)
Set the umask (the bitmask of the permissions
that are not present). The default is the umask of the current process.
The value is given in octal.
Convert all files names to lower case, or
leave them. (Default: case=lower.)
This option is obsolete and may fail or being
ignored.
Do not abort mounting when certain consistency
checks fail.
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 udf filesystem.)Disable the use of Rock Ridge extensions, even
if available. Cf. map.
Disable the use of Microsoft Joliet
extensions, even if available. Cf. map.
With check=relaxed, a filename is first
converted to lower case before doing the lookup. This is probably only
meaningful together with norock and map=normal. (Default:
check=strict.)
Give all files in the filesystem the indicated
user or group id, possibly overriding the information found in the Rock Ridge
extensions. (Default: uid=0,gid=0.)
For non-Rock Ridge volumes, normal name
translation maps upper to lower case ASCII, drops a trailing ';1', and
converts ';' to '.'. With map=off no name translation is done. See
norock. (Default: map=normal.) map=acorn is like
map=normal but also apply Acorn extensions if present.
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.
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.)
Set the block size to the indicated value.
(Default: block=1024.)
This option is obsolete and may fail or being
ignored.
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.
Select number of session on a multisession
CD.
Session begins from sector xxx.
Character set to use for converting 16 bit
Unicode characters on CD to 8 bit characters. The default is iso8859-1.
Convert 16 bit Unicode characters on CD to
UTF-8.
Mount options for jfs
iocharset=nameCharacter set to use for converting from
Unicode to ASCII. The default is to do no conversion. Use
iocharset=utf8 for UTF8 translations. This requires
CONFIG_NLS_UTF8 to be set in the kernel .config file.
Resize the volume to 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 resize
keyword with no value will grow the volume to the full size of the
partition.
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.
Default. Commit metadata changes to the
journal. Use this option to remount a volume where the nointegrity
option was previously specified in order to restore normal behavior.
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.)
These options are accepted but ignored.
Mount options for msdos
See mount options for fat. If the 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.Mount options for ncpfs
Just like nfs, the ncpfs implementation expects a binary argument (a struct ncp_mount_data) to the mount(2) system call. This argument is constructed by ncpmount(8) and the current version of mount (2.12) does not know anything about ncpfs.Mount options for ntfs
iocharset=nameCharacter set to use when returning file
names. Unlike VFAT, NTFS suppresses names that contain nonconvertible
characters. Deprecated.
New name for the option earlier called
iocharset.
Use UTF-8 for converting file names.
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 gives a
little-endian encoding and 1 a byteswapped bigendian encoding.
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.
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.
Mount options for overlay
Since Linux 3.18 the overlay pseudo filesystem implements a union mount for other filesystems.mount -t overlay overlay \ -olowerdir=/lower,upperdir=/upper,workdir=/work /merged
Any filesystem, does not need to be on a
writable filesystem.
The upperdir is normally on a writable
filesystem.
The workdir needs to be an empty directory on
the same filesystem as upperdir.
Use the "user.overlay." xattr
namespace instead of " trusted.overlay.". This is useful for
unprivileged mounting of overlayfs.
If the redirect_dir feature is enabled,
then the directory will be copied up (but not the contents). Then the "{
trusted|user}.overlay.redirect" extended attribute is set
to the path of the original location from the root of the overlay. Finally the
directory is moved to the new location.
on
off
follow
nofollow
Redirects are enabled.
Redirects are not created and only followed if
"redirect_always_follow" feature is enabled in the kernel/module
config.
Redirects are not created, but followed.
Redirects are not created and not followed
(equivalent to "redirect_dir=off" if
"redirect_always_follow" feature is not enabled).
Inode index. If this feature is disabled and a
file with multiple hard links is copied up, then this will "break"
the link. Changes will not be propagated to other names referring to the same
inode.
Can be used to replace UUID of the underlying
filesystem in file handles with null, and effectively disable UUID checks.
This can be useful in case the underlying disk is copied and the UUID of this
copy is changed. This is only applicable if all lower/upper/work directories
are on the same filesystem, otherwise it will fallback to normal
behaviour.
When the underlying filesystems supports NFS
export and the "nfs_export" feature is enabled, an overlay
filesystem may be exported to NFS.
With the "nfs_export" feature, on copy_up of any lower object, an
index entry is created under the index directory. The index entry name is the
hexadecimal representation of the copy up origin file handle. For a
non-directory object, the index entry is a hard link to the upper inode. For a
directory object, the index entry has an extended attribute "{
trusted| user}.overlay.upper" with an encoded file handle
of the upper directory inode.
When encoding a file handle from an overlay filesystem object, the following
rules apply
The encoded overlay file handle includes
This encoding format is identical to the encoding format of file handles that
are stored in extended attribute "{
trusted|user}.overlay.origin". When decoding an overlay
file handle, the following steps are followed
Decoding a non-directory file handle may return a disconnected dentry. copy_up
of that disconnected dentry will create an upper index entry with no upper
alias.
When overlay filesystem has multiple lower layers, a middle layer directory may
have a "redirect" to lower directory. Because middle layer
"redirects" are not indexed, a lower file handle that was encoded
from the "redirect" origin directory, cannot be used to find the
middle or upper layer directory. Similarly, a lower file handle that was
encoded from a descendant of the "redirect" origin directory, cannot
be used to reconstruct a connected overlay path. To mitigate the cases of
directories that cannot be decoded from a lower file handle, these directories
are copied up on encode and encoded as an upper file handle. On an overlay
filesystem with no upper layer this mitigation cannot be used NFS export in
this setup requires turning off redirect follow (e.g. "
redirect_dir=nofollow").
The overlay filesystem does not support non-directory connectable file handles,
so exporting with the subtree_check exportfs configuration will cause
failures to lookup files over NFS.
When the NFS export feature is enabled, all directory index entries are verified
on mount time to check that upper file handles are not stale. This
verification may cause significant overhead in some cases.
Note: the mount options index=off,nfs_export=on are conflicting for a
read-write mount and will result in an error.
•For a non-upper object, encode a lower
file handle from lower inode
•For an indexed object, encode a lower
file handle from copy_up origin
•For a pure-upper object and for an
existing non-indexed upper object, encode an upper file handle from upper
inode
•Header including path type information
(e.g. lower/upper)
•UUID of the underlying
filesystem
•Underlying filesystem encoding of
underlying inode
•Find underlying layer by UUID and path
type information.
•Decode the underlying filesystem file
handle to underlying dentry.
•For a lower file handle, lookup the
handle in index directory by name.
•If a whiteout is found in index,
return ESTALE. This represents an overlay object that was deleted after
its file handle was encoded.
•For a non-directory, instantiate a
disconnected overlay dentry from the decoded underlying dentry, the path type
and index inode, if found.
•For a directory, use the connected
underlying decoded dentry, path type and index, to lookup a connected overlay
dentry.
The "xino" feature composes a unique
object identifier from the real object st_ino and an underlying fsid index.
The "xino" feature uses the high inode number bits for fsid, because
the underlying filesystems rarely use the high inode number bits. In case the
underlying inode number does overflow into the high xino bits, overlay
filesystem will fall back to the non xino behavior for that inode.
For a detailed description of the effect of this option please refer to
<https://www.kernel.org/doc/html/latest/filesystems/overlayfs.html?highlight=overlayfs>
When metadata only copy up feature is enabled,
overlayfs will only copy up metadata (as opposed to whole file), when a
metadata specific operation like chown/chmod is performed. Full file will be
copied up later when file is opened for WRITE operation.
In other words, this is delayed data copy up operation and data is copied up
when there is a need to actually modify data.
Volatile mounts are not guaranteed to survive
a crash. It is strongly recommended that volatile mounts are only used if data
written to the overlay can be recreated without significant effort.
The advantage of mounting with the "volatile" option is that all forms
of sync calls to the upper filesystem are omitted.
In order to avoid a giving a false sense of safety, the syncfs (and fsync)
semantics of volatile mounts are slightly different than that of the rest of
VFS. If any writeback error occurs on the upperdir’s filesystem after a
volatile mount takes place, all sync functions will return an error. Once this
condition is reached, the filesystem will not recover, and every subsequent
sync call will return an error, even if the upperdir has not experience a new
error since the last sync call.
When overlay is mounted with "volatile" option, the directory
"$workdir/work/incompat/volatile" is created. During next mount,
overlay checks for this directory and refuses to mount if present. This is a
strong indicator that user should throw away upper and work directories and
create fresh one. In very limited cases where the user knows that the system
has not crashed and contents of upperdir are intact, The "volatile"
directory can be removed.
Mount options for reiserfs
Reiserfs is a journaling filesystem.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.
Choose which hash function reiserfs will use
to find files within directories.
rupasov
tea
r5
detect
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.
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.
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.
Instructs 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.
Tunes the block allocator. This may provide
performance improvements in some situations.
Tunes the block allocator. This may provide
performance improvements in some situations.
Disable the border allocator algorithm
invented by Yury Yu. Rupasov. This may provide performance improvements in
some situations.
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 nolog is a work in
progress.
By default, reiserfs stores small files and
'file tails' directly into its tree. This confuses some utilities such as
lilo(8). This option is used to disable packing of files into the
tree.
Replay the transactions which are in the
journal, but do not actually mount the filesystem. Mainly used by
reiserfsck.
A remount option which permits online
expansion of reiserfs partitions. Instructs reiserfs to assume that the device
has number blocks. This option is designed for use with devices which
are under logical volume management (LVM). There is a special resizer
utility which can be obtained from
<ftp://ftp.namesys.com/pub/reiserfsprogs> .
Enable Extended User Attributes. See the
attr(1) manual page.
Enable POSIX Access Control Lists. See the
acl(5) manual page.
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.
Mount options for ubifs
UBIFS is a flash filesystem which works on top of UBI volumes. Note that atime is not supported and is always turned off.UBI device number X, volume number
Y
UBI device number 0, volume number
Y
UBI device number X, volume with name
NAME
UBI device number 0, volume with name
NAME
Enable bulk-read. VFS read-ahead is disabled
because it slows down the filesystem. 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.
Do not bulk-read. This is the default.
Check data CRC-32 checksums. This is the
default.
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.
Select the default compressor which is used
when new files are written. It is still possible to read compressed files if
mounted with the none option.
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 iso9660.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".
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".
Mask out the given permissions from all inodes
read from the filesystem. The value is given in octal.
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.
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.
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 mkudffs(8) 2.0+ manpage, see the
COMPATIBILITY and BLOCK SIZE sections.
Show otherwise hidden files.
Show deleted files in lists.
Embed data in the inode. (default)
Don’t embed data in the inode.
Use short UDF address descriptors.
Use long UDF address descriptors.
(default)
Unset strict conformance.
Set the NLS character set. This requires
kernel compiled with CONFIG_UDF_NLS option.
Set the UTF-8 character set.
Mount options for debugging and disaster recovery
novrsIgnore the Volume Recognition Sequence and
attempt to mount anyway.
Select the session number for multi-session
recorded optical media. (default= last session)
Override standard anchor location. (default=
256)
Set the last block of the filesystem.
Unused historical mount options that may be encountered and should be removed
uid=ignoreIgnored, use uid=<user> instead.
Ignored, use gid=<group> instead.
Unimplemented and ignored.
Unimplemented and ignored.
Unimplemented and ignored.
Unimplemented and ignored.
Mount options for ufs
ufstype=valueUFS 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:
old
44bsd
ufs2
5xbsd
sun
sunx86
hp
nextstep
nextstep-cd
openstep
Old format of ufs, this is the default, read
only. (Don’t forget to give the -r option.)
For filesystems created by a BSD-like system
(NetBSD, FreeBSD, OpenBSD).
Used in FreeBSD 5.x supported as
read-write.
Synonym for ufs2.
For filesystems created by SunOS or Solaris on
Sparc.
For filesystems created by Solaris on
x86.
For filesystems created by HP-UX,
read-only.
For filesystems created by NeXTStep (on NeXT
station) (currently read only).
For NextStep CDROMs (block_size == 2048),
read-only.
For filesystems created by OpenStep (currently
read only). The same filesystem type is also used by macOS.
Set behavior on error:
panic
[ lock|umount|repair]
If an error is encountered, cause a kernel
panic.
These mount options don’t do anything
at present; when an error is encountered only a console message is
printed.
Mount options for umsdos
See mount options for msdos. The dotsOK option is explicitly killed by umsdos.Mount options for vfat
First of all, the mount options for fat are recognized. The dotsOK option is explicitly killed by vfat. Furthermore, there areTranslate 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).
Allow two files with names that only differ in
case. This option is obsolete.
First try to make a short name without
sequence number, before trying name~num.ext.
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.
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 modes:
lower
win95
winnt
mixed
Force the short name to lower case upon
display; store a long name when the short name is not all upper case.
Force the short name to upper case upon
display; store a long name when the short name is not all upper case.
Display the short name as is; store a long
name when the short name is not all lower case or all upper case.
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.
Mount options for usbfs
devuid=uid and devgid=gid and devmode=modeSet 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.
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.
Set the owner and group and mode of the file
devices (default: uid=gid=0, mode=0444). The mode is given in
octal.
DM-VERITY SUPPORT
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 the device filesystem is mounted. Requires libcryptsetup with in libmount (optionally via dlopen(3)). 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:Path to the hash tree device associated with
the source volume to pass to dm-verity.
Hex-encoded hash of the root of
verity.hashdevice. Mutually exclusive with
verity.roothashfile.
Path to file containing the hex-encoded hash
of the root of verity.hashdevice. Mutually exclusive with
verity.roothash.
If the hash tree device is embedded in the
source volume, offset (default: 0) is used by dm-verity to get to the
tree.
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.
If the FEC device is embedded in the source
volume, offset (default: 0) is used by dm-verity to get to the FEC
area. Optional.
Parity bytes for FEC (default: 2).
Optional.
Path to pkcs7(1ssl) 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.
Instruct the kernel to ignore, reboot or panic
when corruption is detected. By default the I/O operation simply fails.
Requires Linux 4.1 or newer, and libcrypsetup 2.3.4 or newer. Optional.
mksquashfs /etc /tmp/etc.squashfs dd if=/dev/zero of=/tmp/etc.hash bs=1M count=10 veritysetup format /tmp/etc.squashfs /tmp/etc.hash openssl smime -sign -in <hash> -nocerts -inkey private.key \ -signer private.crt -noattr -binary -outform der -out /tmp/etc.roothash.p7s mount -o verity.hashdevice=/tmp/etc.hash,verity.roothash=<hash>,\ verity.roothashsig=/tmp/etc.roothash.p7s /tmp/etc.squashfs /mnt
LOOP-DEVICE SUPPORT
One further possible type is a mount via the loop device. For example, the commandEXIT STATUS
mount has the following exit status values (the bits can be ORed):success
incorrect invocation or permissions
system error (out of memory, cannot fork, no
more loop devices)
internal mount bug
user interrupt
problems writing or locking
/etc/mtab
mount failure
some mount succeeded
The command mount -a returns 0 (all succeeded), 32 (all failed), or 64
(some failed, some succeeded).
EXTERNAL HELPERS
The syntax of external mount helpers is:ENVIRONMENT
LIBMOUNT_FSTAB=<path>overrides the default location of the
fstab file (ignored for suid)
overrides the default location of the
mtab file (ignored for suid)
enables libmount debug output
enables libblkid debug output
enables loop device setup debug output
FILES
See also " The files /etc/fstab, /etc/mtab and /proc/mounts" section above.filesystem table
libmount private runtime directory
table of mounted filesystems or symlink to
/proc/mounts
lock file (unused on systems with mtab
symlink)
temporary file (unused on systems with
mtab symlink)
a list of filesystem types to try
HISTORY
A mount command existed in Version 5 AT&T UNIX.BUGS
It is possible for a corrupted filesystem to cause a crash.AUTHORS
Karel <[email protected]>ZakSEE ALSO
mount(2), umount(2), filesystems(5), fstab(5), nfs(5), xfs(5), mount_namespaces(7), xattr(7), e2label(8), findmnt(8), losetup(8), lsblk(8), mke2fs(8), mountd(8), nfsd(8), swapon(8), tune2fs(8), umount(8), xfs_admin(8)REPORTING BUGS
For bug reports, use the issue tracker at <https://github.com/util-linux/util-linux/issues>.AVAILABILITY
The mount command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.2022-08-04 | util-linux 2.38.1 |