1MOUNT(8) System Administration MOUNT(8)
2
6 mount - mount a filesystem
7
9 mount [-h|-V]
10 mount [-l] [-t fstype]
12 mount -a [-fFnrsvw] [-t fstype] [-O optlist]
14 mount [-fnrsvw] [-o options] device|mountpoint
16 mount [-fnrsvw] [-t fstype] [-o options] device mountpoint
18 mount --bind|--rbind|--move olddir newdir
20 mount --make-{shared|slave|private|unbindable|rshared|rslave|rpri‐
22 vate|runbindable} mountpoint
23
25 All files accessible in a Unix system are arranged in one big tree, the
26 file hierarchy, rooted at /. These files can be spread out over sev‐
27 eral devices. The mount command serves to attach the filesystem found
28 on some device to the big file tree. Conversely, the umount(8) command
29 will detach it again. The filesystem is used to control how data is
30 stored on the device or provided in a virtual way by network or other
31 services.
32 The standard form of the mount command is:
34 mount -t type device dir
36 This tells the kernel to attach the filesystem found on device (which
38 is of type type) at the directory dir. The option -t type is optional.
39 The mount command is usually able to detect a filesystem. The root
40 permissions are necessary to mount a filesystem by default. See sec‐
41 tion "Non-superuser mounts" below for more details. The previous con‐
42 tents (if any) and owner and mode of dir become invisible, and as long
43 as this filesystem remains mounted, the pathname dir refers to the root
44 of the filesystem on device.
45 If only the directory or the device is given, for example:
47 mount /dir
49 then mount looks for a mountpoint (and if not found then for a device)
51 in the /etc/fstab file. It's possible to use the --target or --source
52 options to avoid ambiguous interpretation of the given argument. For
53 example:
54 mount --target /mountpoint
56 The same filesystem may be mounted more than once, and in some cases
59 (e.g., network filesystems) the same filesystem may be mounted on the
60 same mountpoint multiple times. The mount command does not implement
61 any policy to control this behavior. All behavior is controlled by the
62 kernel and it is usually specific to the filesystem driver. The excep‐
63 tion is --all, in this case already mounted filesystems are ignored
64 (see --all below for more details).
65 Listing the mounts
68 The listing mode is maintained for backward compatibility only.
69 For more robust and customizable output use findmnt(8), especially in
71 your scripts. Note that control characters in the mountpoint name are
72 replaced with '?'.
73 The following command lists all mounted filesystems (of type type):
75 mount [-l] [-t type]
77 The option -l adds labels to this listing. See below.
79 Indicating the device and filesystem
82 Most devices are indicated by a filename (of a block special device),
83 like /dev/sda1, but there are other possibilities. For example, in the
84 case of an NFS mount, device may look like knuth.cwi.nl:/dir.
85 The device names of disk partitions are unstable; hardware reconfigura‐
87 tion, and adding or removing a device can cause changes in names. This
88 is the reason why it's strongly recommended to use filesystem or parti‐
89 tion identifiers like UUID or LABEL. Currently supported identifiers
90 (tags):
91 LABEL=label
93 Human readable filesystem identifier. See also -L.
94 UUID=uuid
96 Filesystem universally unique identifier. The format of
97 the UUID is usually a series of hex digits separated by
98 hyphens. See also -U.
99 Note that mount(8) uses UUIDs as strings. The UUIDs from
101 the command line or from fstab(5) are not converted to
102 internal binary representation. The string representa‐
103 tion of the UUID should be based on lower case charac‐
104 ters.
105 PARTLABEL=label
107 Human readable partition identifier. This identifier is
108 independent on filesystem and does not change by mkfs or
109 mkswap operations It's supported for example for GUID
110 Partition Tables (GPT).
111 PARTUUID=uuid
113 Partition universally unique identifier. This identifier
114 is independent on filesystem and does not change by mkfs
115 or mkswap operations It's supported for example for GUID
116 Partition Tables (GPT).
117 ID=id Hardware block device ID as generated by udevd. This
119 identifier is usually based on WWN (unique storage iden‐
120 tifier) and assigned by the hardware manufacturer. See
121 ls /dev/disk/by-id for more details, this directory and
122 running udevd is required. This identifier is not recom‐
123 mended for generic use as the identifier is not strictly
124 defined and it depends on udev, udev rules and hardware.
125 The command lsblk --fs provides an overview of filesystems, LABELs and
127 UUIDs on available block devices. The command blkid -p <device> pro‐
128 vides details about a filesystem on the specified device.
129 Don't forget that there is no guarantee that UUIDs and labels are re‐
131 ally unique, especially if you move, share or copy the device. Use ls‐
132 blk -o +UUID,PARTUUID to verify that the UUIDs are really unique in
133 your system.
134 The recommended setup is to use tags (e.g. UUID=uuid) rather than
136 /dev/disk/by-{label,uuid,id,partuuid,partlabel} udev symlinks in the
137 /etc/fstab file. Tags are more readable, robust and portable. The
138 mount(8) command internally uses udev symlinks, so the use of symlinks
139 in /etc/fstab has no advantage over tags. For more details see lib‐
140 blkid(3).
141 The proc filesystem is not associated with a special device, and when
143 mounting it, an arbitrary keyword—for example, proc—can be used instead
144 of a device specification. (The customary choice none is less fortu‐
145 nate: the error message `none already mounted' from mount can be con‐
146 fusing.)
147 The files /etc/fstab, /etc/mtab and /proc/mounts
150 The file /etc/fstab (see fstab(5)), may contain lines describing what
151 devices are usually mounted where, using which options. The default
152 location of the fstab(5) file can be overridden with the --fstab path
153 command-line option (see below for more details).
154 The command
156 mount -a [-t type] [-O optlist]
158 (usually given in a bootscript) causes all filesystems mentioned in
160 fstab (of the proper type and/or having or not having the proper op‐
161 tions) to be mounted as indicated, except for those whose line contains
162 the noauto keyword. Adding the -F option will make mount fork, so that
163 the filesystems are mounted in parallel.
164 When mounting a filesystem mentioned in fstab or mtab, it suffices to
166 specify on the command line only the device, or only the mount point.
167 The programs mount and umount traditionally maintained a list of cur‐
169 rently mounted filesystems in the file /etc/mtab. The support for reg‐
170 ular classic /etc/mtab is completely disabled at compile time by de‐
171 fault, because on current Linux systems it is better to make /etc/mtab
172 a symlink to /proc/mounts instead. The regular mtab file maintained in
173 userspace cannot reliably work with namespaces, containers and other
174 advanced Linux features. If the regular mtab support is enabled, then
175 it's possible to use the file as well as the symlink.
176 If no arguments are given to mount, the list of mounted filesystems is
178 printed.
179 If you want to override mount options from /etc/fstab, you have to use
181 the -o option:
182 mount device|dir -o options
184 and then the mount options from the command line will be appended to
186 the list of options from /etc/fstab. This default behaviour can be
187 changed using the --options-mode command-line option. The usual behav‐
188 ior is that the last option wins if there are conflicting ones.
189 The mount program does not read the /etc/fstab file if both device (or
191 LABEL, UUID, ID, PARTUUID or PARTLABEL) and dir are specified. For ex‐
192 ample, to mount device foo at /dir:
193 mount /dev/foo /dir
195 This default behaviour can be changed by using the --op‐
197 tions-source-force command-line option to always read configuration
198 from fstab. For non-root users mount always reads the fstab configura‐
199 tion.
200 Non-superuser mounts
203 Normally, only the superuser can mount filesystems. However, when
204 fstab contains the user option on a line, anybody can mount the corre‐
205 sponding filesystem.
206 Thus, given a line
208 /dev/cdrom /cd iso9660 ro,user,noauto,unhide
210 any user can mount the iso9660 filesystem found on an inserted CDROM
212 using the command:
213 mount /cd
215 Note that mount is very strict about non-root users and all paths spec‐
217 ified on command line are verified before fstab is parsed or a helper
218 program is executed. It's strongly recommended to use a valid mount‐
219 point to specify filesystem, otherwise mount may fail. For example it's
220 a bad idea to use NFS or CIFS source on command line.
221 Since util-linux 2.35, mount does not exit when user permissions are
223 inadequate according to libmount's internal security rules. Instead,
224 it drops suid permissions and continues as regular non-root user. This
225 behavior supports use-cases where root permissions are not necessary
226 (e.g., fuse filesystems, user namespaces, etc).
227 For more details, see fstab(5). Only the user that mounted a filesys‐
229 tem can unmount it again. If any user should be able to unmount it,
230 then use users instead of user in the fstab line. The owner option is
231 similar to the user option, with the restriction that the user must be
232 the owner of the special file. This may be useful e.g. for /dev/fd if
233 a login script makes the console user owner of this device. The group
234 option is similar, with the restriction that the user must be a member
235 of the group of the special file.
236 Bind mount operation
239 Remount part of the file hierarchy somewhere else. The call is:
240 mount --bind olddir newdir
242 or by using this fstab entry:
244 /olddir /newdir none bind
246 After this call the same contents are accessible in two places.
248 It is important to understand that "bind" does not create any second-
250 class or special node in the kernel VFS. The "bind" is just another op‐
251 eration to attach a filesystem. There is nowhere stored information
252 that the filesystem has been attached by a "bind" operation. The olddir
253 and newdir are independent and the olddir may be unmounted.
254 One can also remount a single file (on a single file). It's also pos‐
256 sible to use a bind mount to create a mountpoint from a regular direc‐
257 tory, for example:
258 mount --bind foo foo
260 The bind mount call attaches only (part of) a single filesystem, not
262 possible submounts. The entire file hierarchy including submounts can
263 be attached a second place by using:
264 mount --rbind olddir newdir
266 Note that the filesystem mount options maintained by the kernel will
268 remain the same as those on the original mount point. The userspace
269 mount options (e.g., _netdev) will not be copied by mount and it's nec‐
270 essary to explicitly specify the options on the mount command line.
271 Since util-linux 2.27 mount(8) permits changing the mount options by
273 passing the relevant options along with --bind. For example:
274 mount -o bind,ro foo foo
276 This feature is not supported by the Linux kernel; it is implemented in
278 userspace by an additional mount(2) remounting system call. This solu‐
279 tion is not atomic.
280 The alternative (classic) way to create a read-only bind mount is to
282 use the remount operation, for example:
283 mount --bind olddir newdir
285 mount -o remount,bind,ro olddir newdir
286 Note that a read-only bind will create a read-only mountpoint (VFS en‐
288 try), but the original filesystem superblock will still be writable,
289 meaning that the olddir will be writable, but the newdir will be read-
290 only.
291 It's also possible to change nosuid, nodev, noexec, noatime, nodiratime
293 and relatime VFS entry flags via a "remount,bind" operation. The other
294 flags (for example filesystem-specific flags) are silently ignored.
295 It's impossible to change mount options recursively (for example with
296 -o rbind,ro).
297 Since util-linux 2.31, mount ignores the bind flag from /etc/fstab on a
299 remount operation (if "-o remount" is specified on command line). This
300 is necessary to fully control mount options on remount by command line.
301 In previous versions the bind flag has been always applied and it was
302 impossible to re-define mount options without interaction with the bind
303 semantic. This mount(8) behavior does not affect situations when "re‐
304 mount,bind" is specified in the /etc/fstab file.
305 The move operation
308 Move a mounted tree to another place (atomically). The call is:
309 mount --move olddir newdir
311 This will cause the contents which previously appeared under olddir to
313 now be accessible under newdir. The physical location of the files is
314 not changed. Note that olddir has to be a mountpoint.
315 Note also that moving a mount residing under a shared mount is invalid
317 and unsupported. Use findmnt -o TARGET,PROPAGATION to see the current
318 propagation flags.
319 Shared subtree operations
322 Since Linux 2.6.15 it is possible to mark a mount and its submounts as
323 shared, private, slave or unbindable. A shared mount provides the
324 ability to create mirrors of that mount such that mounts and unmounts
325 within any of the mirrors propagate to the other mirror. A slave mount
326 receives propagation from its master, but not vice versa. A private
327 mount carries no propagation abilities. An unbindable mount is a pri‐
328 vate mount which cannot be cloned through a bind operation. The de‐
329 tailed semantics are documented in Documentation/filesystems/sharedsub‐
330 tree.txt file in the kernel source tree; see also mount_namespaces(7).
331 Supported operations are:
333 mount --make-shared mountpoint
335 mount --make-slave mountpoint
336 mount --make-private mountpoint
337 mount --make-unbindable mountpoint
338 The following commands allow one to recursively change the type of all
340 the mounts under a given mountpoint.
341 mount --make-rshared mountpoint
343 mount --make-rslave mountpoint
344 mount --make-rprivate mountpoint
345 mount --make-runbindable mountpoint
346 mount(8) does not read fstab(5) when a --make-* operation is requested.
348 All necessary information has to be specified on the command line.
349 Note that the Linux kernel does not allow changing multiple propagation
351 flags with a single mount(2) system call, and the flags cannot be mixed
352 with other mount options and operations.
353 Since util-linux 2.23 the mount command can be used to do more propaga‐
355 tion (topology) changes by one mount(8) call and do it also together
356 with other mount operations. This feature is EXPERIMENTAL. The propa‐
357 gation flags are applied by additional mount(2) system calls when the
358 preceding mount operations were successful. Note that this use case is
359 not atomic. It is possible to specify the propagation flags in
360 fstab(5) as mount options (private, slave, shared, unbindable, rpri‐
361 vate, rslave, rshared, runbindable).
362 For example:
364 mount --make-private --make-unbindable /dev/sda1 /foo
366 is the same as:
368 mount /dev/sda1 /foo
370 mount --make-private /foo
371 mount --make-unbindable /foo
372
375 The full set of mount options used by an invocation of mount is deter‐
376 mined by first extracting the mount options for the filesystem from the
377 fstab table, then applying any options specified by the -o argument,
378 and finally applying a -r or -w option, when present.
379 The mount command does not pass all command-line options to the
381 /sbin/mount.suffix mount helpers. The interface between mount and the
382 mount helpers is described below in the section EXTERNAL HELPERS.
383 Command-line options available for the mount command are:
385 -a, --all
387 Mount all filesystems (of the given types) mentioned in fstab
388 (except for those whose line contains the noauto keyword). The
389 filesystems are mounted following their order in fstab. The
390 mount command compares filesystem source, target (and fs root
391 for bind mount or btrfs) to detect already mounted filesystems.
392 The kernel table with already mounted filesystems is cached dur‐
393 ing mount --all. This means that all duplicated fstab entries
394 will be mounted.
395 The option --all is possible to use for remount operation too.
397 In this case all filters (-t and -O) are applied to the table of
398 already mounted filesystems.
399 Since version 2.35 is possible to use the command line option -o
401 to alter mount options from fstab (see also --options-mode).
402 Note that it is a bad practice to use mount -a for fstab check‐
404 ing. The recommended solution is findmnt --verify.
405 -B, --bind
407 Remount a subtree somewhere else (so that its contents are
408 available in both places). See above, under Bind mounts.
409 -c, --no-canonicalize
411 Don't canonicalize paths. The mount command canonicalizes all
412 paths (from the command line or fstab) by default. This option
413 can be used together with the -f flag for already canonicalized
414 absolute paths. The option is designed for mount helpers which
415 call mount -i. It is strongly recommended to not use this com‐
416 mand-line option for normal mount operations.
417 Note that mount(8) does not pass this option to the
419 /sbin/mount.type helpers.
420 -F, --fork
422 (Used in conjunction with -a.) Fork off a new incarnation of
423 mount for each device. This will do the mounts on different de‐
424 vices or different NFS servers in parallel. This has the advan‐
425 tage that it is faster; also NFS timeouts proceed in parallel.
426 A disadvantage is that the order of the mount operations is un‐
427 defined. Thus, you cannot use this option if you want to mount
428 both /usr and /usr/spool.
429 -f, --fake
431 Causes everything to be done except for the actual system call;
432 if it's not obvious, this ``fakes'' mounting the filesystem.
433 This option is useful in conjunction with the -v flag to deter‐
434 mine what the mount command is trying to do. It can also be
435 used to add entries for devices that were mounted earlier with
436 the -n option. The -f option checks for an existing record in
437 /etc/mtab and fails when the record already exists (with a regu‐
438 lar non-fake mount, this check is done by the kernel).
439 -i, --internal-only
441 Don't call the /sbin/mount.filesystem helper even if it exists.
442 -L, --label label
444 Mount the partition that has the specified label.
445 -l, --show-labels
447 Add the labels in the mount output. mount must have permission
448 to read the disk device (e.g. be set-user-ID root) for this to
449 work. One can set such a label for ext2, ext3 or ext4 using the
450 e2label(8) utility, or for XFS using xfs_admin(8), or for reis‐
451 erfs using reiserfstune(8).
452 -M, --move
454 Move a subtree to some other place. See above, the subsection
455 The move operation.
456 -n, --no-mtab
458 Mount without writing in /etc/mtab. This is necessary for exam‐
459 ple when /etc is on a read-only filesystem.
460 -N, --namespace ns
462 Perform the mount operation in the mount namespace specified by
463 ns. ns is either PID of process running in that namespace or
464 special file representing that namespace.
465 mount(8) switches to the mount namespace when it reads
467 /etc/fstab, writes /etc/mtab (or writes to /run/mount) and calls
468 the mount(2) system call, otherwise it runs in the original
469 mount namespace. This means that the target namespace does not
470 have to contain any libraries or other requirements necessary to
471 execute the mount(2) call.
472 See mount_namespaces(7) for more information.
474 -O, --test-opts opts
476 Limit the set of filesystems to which the -a option applies. In
477 this regard it is like the -t option except that -O is useless
478 without -a. For example, the command:
479 mount -a -O no_netdev
481 mounts all filesystems except those which have the option _net‐
483 dev specified in the options field in the /etc/fstab file.
484 It is different from -t in that each option is matched exactly;
486 a leading no at the beginning of one option does not negate the
487 rest.
488 The -t and -O options are cumulative in effect; that is, the
490 command
491 mount -a -t ext2 -O _netdev
493 mounts all ext2 filesystems with the _netdev option, not all
495 filesystems that are either ext2 or have the _netdev option
496 specified.
497 -o, --options opts
499 Use the specified mount options. The opts argument is a comma-
500 separated list. For example:
501 mount LABEL=mydisk -o noatime,nodev,nosuid
503 For more details, see the FILESYSTEM-INDEPENDENT MOUNT OPTIONS
506 and FILESYSTEM-SPECIFIC MOUNT OPTIONS sections.
507 --options-mode mode
510 Controls how to combine options from fstab/mtab with options
511 from the command line. mode can be one of ignore, append,
512 prepend or replace. For example, append means that options from
513 fstab are appended to options from the command line. The de‐
514 fault value is prepend -- it means command line options are
515 evaluated after fstab options. Note that the last option wins
516 if there are conflicting ones.
517 --options-source source
520 Source of default options. source is a comma-separated list of
521 fstab, mtab and disable. disable disables fstab and mtab and
522 disables --options-source-force. The default value is
523 fstab,mtab.
524 --options-source-force
527 Use options from fstab/mtab even if both device and dir are
528 specified.
529 -R, --rbind
532 Remount a subtree and all possible submounts somewhere else (so
533 that its contents are available in both places). See above, the
534 subsection Bind mounts.
535 -r, --read-only
537 Mount the filesystem read-only. A synonym is -o ro.
538 Note that, depending on the filesystem type, state and kernel
540 behavior, the system may still write to the device. For exam‐
541 ple, ext3 and ext4 will replay the journal if the filesystem is
542 dirty. To prevent this kind of write access, you may want to
543 mount an ext3 or ext4 filesystem with the ro,noload mount op‐
544 tions or set the block device itself to read-only mode, see the
545 blockdev(8) command.
546 -s Tolerate sloppy mount options rather than failing. This will
548 ignore mount options not supported by a filesystem type. Not
549 all filesystems support this option. Currently it's supported
550 by the mount.nfs mount helper only.
551 --source device
553 If only one argument for the mount command is given, then the
554 argument might be interpreted as the target (mountpoint) or
555 source (device). This option allows you to explicitly define
556 that the argument is the mount source.
557 --target directory
559 If only one argument for the mount command is given, then the
560 argument might be interpreted as the target (mountpoint) or
561 source (device). This option allows you to explicitly define
562 that the argument is the mount target.
563 --target-prefix directory
565 Prepend the specified directory to all mount targets. This op‐
566 tion can be used to follow fstab, but mount operations are done
567 in another place, for example:
568 mount --all --target-prefix /chroot -o X-mount.mkdir
570 mounts all from system fstab to /chroot, all missing mountpoint
572 are created (due to X-mount.mkdir). See also --fstab to use an
573 alternative fstab.
574 -T, --fstab path
576 Specifies an alternative fstab file. If path is a directory,
577 then the files in the directory are sorted by strverscmp(3);
578 files that start with "." or without an .fstab extension are ig‐
579 nored. The option can be specified more than once. This option
580 is mostly designed for initramfs or chroot scripts where addi‐
581 tional configuration is specified beyond standard system config‐
582 uration.
583 Note that mount(8) does not pass the option --fstab to the
585 /sbin/mount.type helpers, meaning that the alternative fstab
586 files will be invisible for the helpers. This is no problem for
587 normal mounts, but user (non-root) mounts always require fstab
588 to verify the user's rights.
589 -t, --types fstype
591 The argument following the -t is used to indicate the filesystem
592 type. The filesystem types which are currently supported depend
593 on the running kernel. See /proc/filesystems and /lib/mod‐
594 ules/$(uname -r)/kernel/fs for a complete list of the filesys‐
595 tems. The most common are ext2, ext3, ext4, xfs, btrfs, vfat,
596 sysfs, proc, nfs and cifs.
597 The programs mount and umount support filesystem subtypes. The
599 subtype is defined by a '.subtype' suffix. For example
600 'fuse.sshfs'. It's recommended to use subtype notation rather
601 than add any prefix to the mount source (for example 'sshfs#ex‐
602 ample.com' is deprecated).
603 If no -t option is given, or if the auto type is specified,
605 mount will try to guess the desired type. Mount uses the blkid
606 library for guessing the filesystem type; if that does not turn
607 up anything that looks familiar, mount will try to read the file
608 /etc/filesystems, or, if that does not exist, /proc/filesystems.
609 All of the filesystem types listed there will be tried, except
610 for those that are labeled "nodev" (e.g. devpts, proc and nfs).
611 If /etc/filesystems ends in a line with a single *, mount will
612 read /proc/filesystems afterwards. While trying, all filesystem
613 types will be mounted with the mount option silent.
614 The auto type may be useful for user-mounted floppies. Creating
616 a file /etc/filesystems can be useful to change the probe order
617 (e.g., to try vfat before msdos or ext3 before ext2) or if you
618 use a kernel module autoloader.
619 More than one type may be specified in a comma-separated list,
621 for the -t option as well as in an /etc/fstab entry. The list
622 of filesystem types for the -t option can be prefixed with no to
623 specify the filesystem types on which no action should be taken.
624 The prefix no has no effect when specified in an /etc/fstab en‐
625 try.
626 The prefix no can be meaningful with the -a option. For exam‐
628 ple, the command
629 mount -a -t nomsdos,smbfs
631 mounts all filesystems except those of type msdos and smbfs.
633 For most types all the mount program has to do is issue a simple
635 mount(2) system call, and no detailed knowledge of the filesys‐
636 tem type is required. For a few types however (like nfs, nfs4,
637 cifs, smbfs, ncpfs) an ad hoc code is necessary. The nfs, nfs4,
638 cifs, smbfs, and ncpfs filesystems have a separate mount pro‐
639 gram. In order to make it possible to treat all types in a uni‐
640 form way, mount will execute the program /sbin/mount.type (if
641 that exists) when called with type type. Since different ver‐
642 sions of the smbmount program have different calling conven‐
643 tions, /sbin/mount.smbfs may have to be a shell script that sets
644 up the desired call.
645 -U, --uuid uuid
647 Mount the partition that has the specified uuid.
648 -v, --verbose
650 Verbose mode.
651 -w, --rw, --read-write
653 Mount the filesystem read/write. Read-write is the kernel de‐
654 fault and the mount default is to try read-only if the previous
655 mount syscall with read-write flags on write-protected devices
656 of filesystems failed.
657 A synonym is -o rw.
659 Note that specifying -w on the command line forces mount to
661 never try read-only mount on write-protected devices or already
662 mounted read-only filesystems.
663 -V, --version
665 Display version information and exit.
666 -h, --help
668 Display help text and exit.
669
672 Some of these options are only useful when they appear in the
673 /etc/fstab file.
674 Some of these options could be enabled or disabled by default in the
676 system kernel. To check the current setting see the options in
677 /proc/mounts. Note that filesystems also have per-filesystem specific
678 default mount options (see for example tune2fs -l output for extN
679 filesystems).
680 The following options apply to any filesystem that is being mounted
682 (but not every filesystem actually honors them – e.g., the sync option
683 today has an effect only for ext2, ext3, ext4, fat, vfat, ufs and xfs):
684 async All I/O to the filesystem should be done asynchronously. (See
687 also the sync option.)
688 atime Do not use the noatime feature, so the inode access time is con‐
690 trolled by kernel defaults. See also the descriptions of the
691 relatime and strictatime mount options.
692 noatime
694 Do not update inode access times on this filesystem (e.g. for
695 faster access on the news spool to speed up news servers). This
696 works for all inode types (directories too), so it implies
697 nodiratime.
698 auto Can be mounted with the -a option.
700 noauto Can only be mounted explicitly (i.e., the -a option will not
702 cause the filesystem to be mounted).
703 context=context, fscontext=context, defcontext=context, and
705 rootcontext=context
706 The context= option is useful when mounting filesystems that do
707 not support extended attributes, such as a floppy or hard disk
708 formatted with VFAT, or systems that are not normally running
709 under SELinux, such as an ext3 or ext4 formatted disk from a
710 non-SELinux workstation. You can also use context= on filesys‐
711 tems you do not trust, such as a floppy. It also helps in com‐
712 patibility with xattr-supporting filesystems on earlier 2.4.<x>
713 kernel versions. Even where xattrs are supported, you can save
714 time not having to label every file by assigning the entire disk
715 one security context.
716 A commonly used option for removable media is
718 context="system_u:object_r:removable_t".
719 Two other options are fscontext= and defcontext=, both of which
721 are mutually exclusive of the context= option. This means you
722 can use fscontext and defcontext with each other, but neither
723 can be used with context.
724 The fscontext= option works for all filesystems, regardless of
726 their xattr support. The fscontext option sets the overarching
727 filesystem label to a specific security context. This filesys‐
728 tem label is separate from the individual labels on the files.
729 It represents the entire filesystem for certain kinds of permis‐
730 sion checks, such as during mount or file creation. Individual
731 file labels are still obtained from the xattrs on the files
732 themselves. The context option actually sets the aggregate con‐
733 text that fscontext provides, in addition to supplying the same
734 label for individual files.
735 You can set the default security context for unlabeled files us‐
737 ing defcontext= option. This overrides the value set for unla‐
738 beled files in the policy and requires a filesystem that sup‐
739 ports xattr labeling.
740 The rootcontext= option allows you to explicitly label the root
742 inode of a FS being mounted before that FS or inode becomes vis‐
743 ible to userspace. This was found to be useful for things like
744 stateless Linux.
745 Note that the kernel rejects any remount request that includes
747 the context option, even when unchanged from the current con‐
748 text.
749 Warning: the context value might contain commas, in which case
751 the value has to be properly quoted, otherwise mount(8) will in‐
752 terpret the comma as a separator between mount options. Don't
753 forget that the shell strips off quotes and thus double quoting
754 is required. For example:
755 mount -t tmpfs none /mnt -o \
757 'context="system_u:object_r:tmp_t:s0:c127,c456",noexec'
758 For more details, see selinux(8).
760 defaults
763 Use the default options: rw, suid, dev, exec, auto, nouser, and
764 async.
765 Note that the real set of all default mount options depends on
767 the kernel and filesystem type. See the beginning of this sec‐
768 tion for more details.
769 dev Interpret character or block special devices on the filesystem.
771 nodev Do not interpret character or block special devices on the
773 filesystem.
774 diratime
776 Update directory inode access times on this filesystem. This is
777 the default. (This option is ignored when noatime is set.)
778 nodiratime
780 Do not update directory inode access times on this filesystem.
781 (This option is implied when noatime is set.)
782 dirsync
784 All directory updates within the filesystem should be done syn‐
785 chronously. This affects the following system calls: creat,
786 link, unlink, symlink, mkdir, rmdir, mknod and rename.
787 exec Permit execution of binaries.
789 noexec Do not permit direct execution of any binaries on the mounted
791 filesystem.
792 group Allow an ordinary user to mount the filesystem if one of that
794 user's groups matches the group of the device. This option im‐
795 plies the options nosuid and nodev (unless overridden by subse‐
796 quent options, as in the option line group,dev,suid).
797 iversion
799 Every time the inode is modified, the i_version field will be
800 incremented.
801 noiversion
803 Do not increment the i_version inode field.
804 mand Allow mandatory locks on this filesystem. See fcntl(2).
806 nomand Do not allow mandatory locks on this filesystem.
808 _netdev
810 The filesystem resides on a device that requires network access
811 (used to prevent the system from attempting to mount these
812 filesystems until the network has been enabled on the system).
813 nofail Do not report errors for this device if it does not exist.
815 relatime
817 Update inode access times relative to modify or change time.
818 Access time is only updated if the previous access time was ear‐
819 lier than the current modify or change time. (Similar to
820 noatime, but it doesn't break mutt or other applications that
821 need to know if a file has been read since the last time it was
822 modified.)
823 Since Linux 2.6.30, the kernel defaults to the behavior provided
825 by this option (unless noatime was specified), and the
826 strictatime option is required to obtain traditional semantics.
827 In addition, since Linux 2.6.30, the file's last access time is
828 always updated if it is more than 1 day old.
829 norelatime
831 Do not use the relatime feature. See also the strictatime mount
832 option.
833 strictatime
835 Allows to explicitly request full atime updates. This makes it
836 possible for the kernel to default to relatime or noatime but
837 still allow userspace to override it. For more details about
838 the default system mount options see /proc/mounts.
839 nostrictatime
841 Use the kernel's default behavior for inode access time updates.
842 lazytime
844 Only update times (atime, mtime, ctime) on the in-memory version
845 of the file inode.
846 This mount option significantly reduces writes to the inode ta‐
848 ble for workloads that perform frequent random writes to preal‐
849 located files.
850 The on-disk timestamps are updated only when:
852 - the inode needs to be updated for some change unrelated to
854 file timestamps
855 - the application employs fsync(2), syncfs(2), or sync(2)
857 - an undeleted inode is evicted from memory
859 - more than 24 hours have passed since the inode was written to
861 disk.
862 nolazytime
865 Do not use the lazytime feature.
866 suid Honor set-user-ID and set-group-ID bits or file capabilities
868 when executing programs from this filesystem.
869 nosuid Do not honor set-user-ID and set-group-ID bits or file capabili‐
871 ties when executing programs from this filesystem.
872 silent Turn on the silent flag.
874 loud Turn off the silent flag.
876 owner Allow an ordinary user to mount the filesystem if that user is
878 the owner of the device. This option implies the options nosuid
879 and nodev (unless overridden by subsequent options, as in the
880 option line owner,dev,suid).
881 remount
883 Attempt to remount an already-mounted filesystem. This is com‐
884 monly used to change the mount flags for a filesystem, espe‐
885 cially to make a readonly filesystem writable. It does not
886 change device or mount point.
887 The remount operation together with the bind flag has special
889 semantics. See above, the subsection Bind mounts.
890 The remount functionality follows the standard way the mount
892 command works with options from fstab. This means that mount
893 does not read fstab (or mtab) only when both device and dir are
894 specified.
895 mount -o remount,rw /dev/foo /dir
897 After this call all old mount options are replaced and arbitrary
899 stuff from fstab (or mtab) is ignored, except the loop= option
900 which is internally generated and maintained by the mount com‐
901 mand.
902 mount -o remount,rw /dir
904 After this call, mount reads fstab and merges these options with
906 the options from the command line (-o). If no mountpoint is
907 found in fstab, then a remount with unspecified source is al‐
908 lowed.
909 mount allows the use of --all to remount all already mounted
911 filesystems which match a specified filter (-O and -t). For ex‐
912 ample:
913 mount --all -o remount,ro -t vfat
915 remounts all already mounted vfat filesystems in read-only mode.
917 Each of the filesystems is remounted by "mount -o remount,ro
918 /dir" semantic. This means the mount command reads fstab or
919 mtab and merges these options with the options from the command
920 line.
921 ro Mount the filesystem read-only.
923 rw Mount the filesystem read-write.
925 sync All I/O to the filesystem should be done synchronously. In the
927 case of media with a limited number of write cycles (e.g. some
928 flash drives), sync may cause life-cycle shortening.
929 user Allow an ordinary user to mount the filesystem. The name of the
931 mounting user is written to the mtab file (or to the private
932 libmount file in /run/mount on systems without a regular mtab)
933 so that this same user can unmount the filesystem again. This
934 option implies the options noexec, nosuid, and nodev (unless
935 overridden by subsequent options, as in the option line
936 user,exec,dev,suid).
937 nouser Forbid an ordinary user to mount the filesystem. This is the
939 default; it does not imply any other options.
940 users Allow any user to mount and to unmount the filesystem, even when
942 some other ordinary user mounted it. This option implies the
943 options noexec, nosuid, and nodev (unless overridden by subse‐
944 quent options, as in the option line users,exec,dev,suid).
945 X-* All options prefixed with "X-" are interpreted as comments or as
947 userspace application-specific options. These options are not
948 stored in user space (e.g., mtab file), nor sent to the
949 mount.type helpers nor to the mount(2) system call. The sug‐
950 gested format is X-appname.option.
951 x-* The same as X-* options, but stored permanently in user space.
953 This means the options are also available for umount or other
954 operations. Note that maintaining mount options in user space
955 is tricky, because it's necessary use libmount-based tools and
956 there is no guarantee that the options will be always available
957 (for example after a move mount operation or in unshared name‐
958 space).
959 Note that before util-linux v2.30 the x-* options have not been
961 maintained by libmount and stored in user space (functionality
962 was the same as for X-* now), but due to the growing number of
963 use-cases (in initrd, systemd etc.) the functionality has been
964 extended to keep existing fstab configurations usable without a
965 change.
966 X-mount.mkdir[=mode]
968 Allow to make a target directory (mountpoint) if it does not
969 exit yet. The optional argument mode specifies the filesystem
970 access mode used for mkdir(2) in octal notation. The default
971 mode is 0755. This functionality is supported only for root
972 users or when mount executed without suid permissions. The op‐
973 tion is also supported as x-mount.mkdir, this notation is depre‐
974 cated since v2.30.
975 nosymfollow
977 Do not follow symlinks when resolving paths. Symlinks can still
978 be created, and readlink(1), readlink(2), realpath(1) and real‐
979 path(3) all still work properly.
980
983 This section lists options that are specific to particular filesystems.
984 Where possible, you should first consult filesystem-specific manual
985 pages for details. Some of those pages are listed in the following ta‐
986 ble.
987 Filesystem(s) Manual page
989 btrfs btrfs(5)
990 cifs mount.cifs(8)
991 ext2, ext3, ext4 ext4(5)
992 fuse fuse(8)
993 nfs nfs(5)
994 tmpfs tmpfs(5)
995 xfs xfs(5)
996 Note that some of the pages listed above might be available only after
998 you install the respective userland tools.
999 The following options apply only to certain filesystems. We sort them
1001 by filesystem. All options follow the -o flag.
1002 What options are supported depends a bit on the running kernel. Fur‐
1004 ther information may be available in filesystem-specific files in the
1005 kernel source subdirectory Documentation/filesystems.
1006 Mount options for adfs
1008 uid=value and gid=value
1009 Set the owner and group of the files in the filesystem (default:
1010 uid=gid=0).
1011 ownmask=value and othmask=value
1013 Set the permission mask for ADFS 'owner' permissions and 'other'
1014 permissions, respectively (default: 0700 and 0077, respec‐
1015 tively). See also /usr/src/linux/Documentation/filesys‐
1016 tems/adfs.rst.
1017 Mount options for affs
1020 uid=value and gid=value
1021 Set the owner and group of the root of the filesystem (default:
1022 uid=gid=0, but with option uid or gid without specified value,
1023 the UID and GID of the current process are taken).
1024 setuid=value and setgid=value
1026 Set the owner and group of all files.
1027 mode=value
1029 Set the mode of all files to value & 0777 disregarding the orig‐
1030 inal permissions. Add search permission to directories that
1031 have read permission. The value is given in octal.
1032 protect
1034 Do not allow any changes to the protection bits on the filesys‐
1035 tem.
1036 usemp Set UID and GID of the root of the filesystem to the UID and GID
1038 of the mount point upon the first sync or umount, and then clear
1039 this option. Strange...
1040 verbose
1042 Print an informational message for each successful mount.
1043 prefix=string
1045 Prefix used before volume name, when following a link.
1046 volume=string
1048 Prefix (of length at most 30) used before '/' when following a
1049 symbolic link.
1050 reserved=value
1052 (Default: 2.) Number of unused blocks at the start of the de‐
1053 vice.
1054 root=value
1056 Give explicitly the location of the root block.
1057 bs=value
1059 Give blocksize. Allowed values are 512, 1024, 2048, 4096.
1060 grpquota|noquota|quota|usrquota
1062 These options are accepted but ignored. (However, quota utili‐
1063 ties may react to such strings in /etc/fstab.)
1064 Mount options for debugfs
1067 The debugfs filesystem is a pseudo filesystem, traditionally mounted on
1068 /sys/kernel/debug. As of kernel version 3.4, debugfs has the following
1069 options:
1070 uid=n, gid=n
1072 Set the owner and group of the mountpoint.
1073 mode=value
1075 Sets the mode of the mountpoint.
1076 Mount options for devpts
1079 The devpts filesystem is a pseudo filesystem, traditionally mounted on
1080 /dev/pts. In order to acquire a pseudo terminal, a process opens
1081 /dev/ptmx; the number of the pseudo terminal is then made available to
1082 the process and the pseudo terminal slave can be accessed as
1083 /dev/pts/<number>.
1084 uid=value and gid=value
1086 This sets the owner or the group of newly created pseudo termi‐
1087 nals to the specified values. When nothing is specified, they
1088 will be set to the UID and GID of the creating process. For ex‐
1089 ample, if there is a tty group with GID 5, then gid=5 will cause
1090 newly created pseudo terminals to belong to the tty group.
1091 mode=value
1093 Set the mode of newly created pseudo terminals to the specified
1094 value. The default is 0600. A value of mode=620 and gid=5
1095 makes "mesg y" the default on newly created pseudo terminals.
1096 newinstance
1098 Create a private instance of the devpts filesystem, such that
1099 indices of pseudo terminals allocated in this new instance are
1100 independent of indices created in other instances of devpts.
1101 All mounts of devpts without this newinstance option share the
1103 same set of pseudo terminal indices (i.e., legacy mode). Each
1104 mount of devpts with the newinstance option has a private set of
1105 pseudo terminal indices.
1106 This option is mainly used to support containers in the Linux
1108 kernel. It is implemented in Linux kernel versions starting
1109 with 2.6.29. Further, this mount option is valid only if CON‐
1110 FIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the kernel configu‐
1111 ration.
1112 To use this option effectively, /dev/ptmx must be a symbolic
1114 link to pts/ptmx. See Documentation/filesystems/devpts.txt in
1115 the Linux kernel source tree for details.
1116 ptmxmode=value
1118 Set the mode for the new ptmx device node in the devpts filesys‐
1120 tem.
1121 With the support for multiple instances of devpts (see newin‐
1123 stance option above), each instance has a private ptmx node in
1124 the root of the devpts filesystem (typically /dev/pts/ptmx).
1125 For compatibility with older versions of the kernel, the default
1127 mode of the new ptmx node is 0000. ptmxmode=value specifies a
1128 more useful mode for the ptmx node and is highly recommended
1129 when the newinstance option is specified.
1130 This option is only implemented in Linux kernel versions start‐
1132 ing with 2.6.29. Further, this option is valid only if CON‐
1133 FIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the kernel configu‐
1134 ration.
1135 Mount options for fat
1138 (Note: fat is not a separate filesystem, but a common part of the ms‐
1139 dos, umsdos and vfat filesystems.)
1140 blocksize={512|1024|2048}
1142 Set blocksize (default 512). This option is obsolete.
1143 uid=value and gid=value
1145 Set the owner and group of all files. (Default: the UID and GID
1146 of the current process.)
1147 umask=value
1149 Set the umask (the bitmask of the permissions that are not
1150 present). The default is the umask of the current process. The
1151 value is given in octal.
1152 dmask=value
1154 Set the umask applied to directories only. The default is the
1155 umask of the current process. The value is given in octal.
1156 fmask=value
1158 Set the umask applied to regular files only. The default is the
1159 umask of the current process. The value is given in octal.
1160 allow_utime=value
1162 This option controls the permission check of mtime/atime.
1163 20 If current process is in group of file's group ID, you
1165 can change timestamp.
1166 2 Other users can change timestamp.
1168 The default is set from `dmask' option. (If the directory is
1170 writable, utime(2) is also allowed. I.e. ~dmask & 022)
1171 Normally utime(2) checks that the current process is owner of
1173 the file, or that it has the CAP_FOWNER capability. But FAT
1174 filesystems don't have UID/GID on disk, so the normal check is
1175 too inflexible. With this option you can relax it.
1176 check=value
1178 Three different levels of pickiness can be chosen:
1179 r[elaxed]
1181 Upper and lower case are accepted and equivalent, long
1182 name parts are truncated (e.g. verylongname.foobar be‐
1183 comes verylong.foo), leading and embedded spaces are ac‐
1184 cepted in each name part (name and extension).
1185 n[ormal]
1187 Like "relaxed", but many special characters (*, ?, <,
1188 spaces, etc.) are rejected. This is the default.
1189 s[trict]
1191 Like "normal", but names that contain long parts or spe‐
1192 cial characters that are sometimes used on Linux but are
1193 not accepted by MS-DOS (+, =, etc.) are rejected.
1194 codepage=value
1196 Sets the codepage for converting to shortname characters on FAT
1197 and VFAT filesystems. By default, codepage 437 is used.
1198 conv=mode
1200 This option is obsolete and may fail or be ignored.
1201 cvf_format=module
1203 Forces the driver to use the CVF (Compressed Volume File) module
1204 cvf_module instead of auto-detection. If the kernel supports
1205 kmod, the cvf_format=xxx option also controls on-demand CVF mod‐
1206 ule loading. This option is obsolete.
1207 cvf_option=option
1209 Option passed to the CVF module. This option is obsolete.
1210 debug Turn on the debug flag. A version string and a list of filesys‐
1212 tem parameters will be printed (these data are also printed if
1213 the parameters appear to be inconsistent).
1214 discard
1216 If set, causes discard/TRIM commands to be issued to the block
1217 device when blocks are freed. This is useful for SSD devices
1218 and sparse/thinly-provisioned LUNs.
1219 dos1xfloppy
1221 If set, use a fallback default BIOS Parameter Block configura‐
1222 tion, determined by backing device size. These static parame‐
1223 ters match defaults assumed by DOS 1.x for 160 kiB, 180 kiB, 320
1224 kiB, and 360 kiB floppies and floppy images.
1225 errors={panic|continue|remount-ro}
1227 Specify FAT behavior on critical errors: panic, continue without
1228 doing anything, or remount the partition in read-only mode (de‐
1229 fault behavior).
1230 fat={12|16|32}
1232 Specify a 12, 16 or 32 bit fat. This overrides the automatic
1233 FAT type detection routine. Use with caution!
1234 iocharset=value
1236 Character set to use for converting between 8 bit characters and
1237 16 bit Unicode characters. The default is iso8859-1. Long
1238 filenames are stored on disk in Unicode format.
1239 nfs={stale_rw|nostale_ro}
1241 Enable this only if you want to export the FAT filesystem over
1242 NFS.
1243 stale_rw: This option maintains an index (cache) of directory
1245 inodes which is used by the nfs-related code to improve look-
1246 ups. Full file operations (read/write) over NFS are supported
1247 but with cache eviction at NFS server, this could result in spu‐
1248 rious ESTALE errors.
1249 nostale_ro: This option bases the inode number and file handle
1251 on the on-disk location of a file in the FAT directory entry.
1252 This ensures that ESTALE will not be returned after a file is
1253 evicted from the inode cache. However, it means that operations
1254 such as rename, create and unlink could cause file handles that
1255 previously pointed at one file to point at a different file, po‐
1256 tentially causing data corruption. For this reason, this option
1257 also mounts the filesystem readonly.
1258 To maintain backward compatibility, '-o nfs' is also accepted,
1260 defaulting to stale_rw.
1261 tz=UTC This option disables the conversion of timestamps between local
1263 time (as used by Windows on FAT) and UTC (which Linux uses in‐
1264 ternally). This is particularly useful when mounting devices
1265 (like digital cameras) that are set to UTC in order to avoid the
1266 pitfalls of local time.
1267 time_offset=minutes
1269 Set offset for conversion of timestamps from local time used by
1270 FAT to UTC. I.e., minutes will be subtracted from each time‐
1271 stamp to convert it to UTC used internally by Linux. This is
1272 useful when the time zone set in the kernel via settimeofday(2)
1273 is not the time zone used by the filesystem. Note that this op‐
1274 tion still does not provide correct time stamps in all cases in
1275 presence of DST - time stamps in a different DST setting will be
1276 off by one hour.
1277 quiet Turn on the quiet flag. Attempts to chown or chmod files do not
1279 return errors, although they fail. Use with caution!
1280 rodir FAT has the ATTR_RO (read-only) attribute. On Windows, the
1282 ATTR_RO of the directory will just be ignored, and is used only
1283 by applications as a flag (e.g. it's set for the customized
1284 folder).
1285 If you want to use ATTR_RO as read-only flag even for the direc‐
1287 tory, set this option.
1288 showexec
1290 If set, the execute permission bits of the file will be allowed
1291 only if the extension part of the name is .EXE, .COM, or .BAT.
1292 Not set by default.
1293 sys_immutable
1295 If set, ATTR_SYS attribute on FAT is handled as IMMUTABLE flag
1296 on Linux. Not set by default.
1297 flush If set, the filesystem will try to flush to disk more early than
1299 normal. Not set by default.
1300 usefree
1302 Use the "free clusters" value stored on FSINFO. It'll be used
1303 to determine number of free clusters without scanning disk. But
1304 it's not used by default, because recent Windows don't update it
1305 correctly in some case. If you are sure the "free clusters" on
1306 FSINFO is correct, by this option you can avoid scanning disk.
1307 dots, nodots, dotsOK=[yes|no]
1309 Various misguided attempts to force Unix or DOS conventions onto
1310 a FAT filesystem.
1311 Mount options for hfs
1314 creator=cccc, type=cccc
1315 Set the creator/type values as shown by the MacOS finder used
1316 for creating new files. Default values: '????'.
1317 uid=n, gid=n
1319 Set the owner and group of all files. (Default: the UID and GID
1320 of the current process.)
1321 dir_umask=n, file_umask=n, umask=n
1323 Set the umask used for all directories, all regular files, or
1324 all files and directories. Defaults to the umask of the current
1325 process.
1326 session=n
1328 Select the CDROM session to mount. Defaults to leaving that de‐
1329 cision to the CDROM driver. This option will fail with anything
1330 but a CDROM as underlying device.
1331 part=n Select partition number n from the device. Only makes sense for
1333 CDROMs. Defaults to not parsing the partition table at all.
1334 quiet Don't complain about invalid mount options.
1336 Mount options for hpfs
1339 uid=value and gid=value
1340 Set the owner and group of all files. (Default: the UID and GID
1341 of the current process.)
1342 umask=value
1344 Set the umask (the bitmask of the permissions that are not
1345 present). The default is the umask of the current process. The
1346 value is given in octal.
1347 case={lower|asis}
1349 Convert all files names to lower case, or leave them. (Default:
1350 case=lower.)
1351 conv=mode
1353 This option is obsolete and may fail or being ignored.
1354 nocheck
1356 Do not abort mounting when certain consistency checks fail.
1357 Mount options for iso9660
1360 ISO 9660 is a standard describing a filesystem structure to be used on
1361 CD-ROMs. (This filesystem type is also seen on some DVDs. See also the
1362 udf filesystem.)
1363 Normal iso9660 filenames appear in an 8.3 format (i.e., DOS-like re‐
1365 strictions on filename length), and in addition all characters are in
1366 upper case. Also there is no field for file ownership, protection,
1367 number of links, provision for block/character devices, etc.
1368 Rock Ridge is an extension to iso9660 that provides all of these UNIX-
1370 like features. Basically there are extensions to each directory record
1371 that supply all of the additional information, and when Rock Ridge is
1372 in use, the filesystem is indistinguishable from a normal UNIX filesys‐
1373 tem (except that it is read-only, of course).
1374 norock Disable the use of Rock Ridge extensions, even if available.
1376 Cf. map.
1377 nojoliet
1379 Disable the use of Microsoft Joliet extensions, even if avail‐
1380 able. Cf. map.
1381 check={r[elaxed]|s[trict]}
1383 With check=relaxed, a filename is first converted to lower case
1384 before doing the lookup. This is probably only meaningful to‐
1385 gether with norock and map=normal. (Default: check=strict.)
1386 uid=value and gid=value
1388 Give all files in the filesystem the indicated user or group id,
1389 possibly overriding the information found in the Rock Ridge ex‐
1390 tensions. (Default: uid=0,gid=0.)
1391 map={n[ormal]|o[ff]|a[corn]}
1393 For non-Rock Ridge volumes, normal name translation maps upper
1394 to lower case ASCII, drops a trailing `;1', and converts `;' to
1395 `.'. With map=off no name translation is done. See norock.
1396 (Default: map=normal.) map=acorn is like map=normal but also
1397 apply Acorn extensions if present.
1398 mode=value
1400 For non-Rock Ridge volumes, give all files the indicated mode.
1401 (Default: read and execute permission for everybody.) Octal
1402 mode values require a leading 0.
1403 unhide Also show hidden and associated files. (If the ordinary files
1405 and the associated or hidden files have the same filenames, this
1406 may make the ordinary files inaccessible.)
1407 block={512|1024|2048}
1409 Set the block size to the indicated value. (Default:
1410 block=1024.)
1411 conv=mode
1413 This option is obsolete and may fail or being ignored.
1414 cruft If the high byte of the file length contains other garbage, set
1416 this mount option to ignore the high order bits of the file
1417 length. This implies that a file cannot be larger than 16 MB.
1418 session=x
1420 Select number of session on multisession CD.
1421 sbsector=xxx
1423 Session begins from sector xxx.
1424 The following options are the same as for vfat and specifying them only
1426 makes sense when using discs encoded using Microsoft's Joliet exten‐
1427 sions.
1428 iocharset=value
1430 Character set to use for converting 16 bit Unicode characters on
1431 CD to 8 bit characters. The default is iso8859-1.
1432 utf8 Convert 16 bit Unicode characters on CD to UTF-8.
1434 Mount options for jfs
1437 iocharset=name
1438 Character set to use for converting from Unicode to ASCII. The
1439 default is to do no conversion. Use iocharset=utf8 for UTF8
1440 translations. This requires CONFIG_NLS_UTF8 to be set in the
1441 kernel .config file.
1442 resize=value
1444 Resize the volume to value blocks. JFS only supports growing a
1445 volume, not shrinking it. This option is only valid during a
1446 remount, when the volume is mounted read-write. The resize key‐
1447 word with no value will grow the volume to the full size of the
1448 partition.
1449 nointegrity
1451 Do not write to the journal. The primary use of this option is
1452 to allow for higher performance when restoring a volume from
1453 backup media. The integrity of the volume is not guaranteed if
1454 the system abnormally ends.
1455 integrity
1457 Default. Commit metadata changes to the journal. Use this op‐
1458 tion to remount a volume where the nointegrity option was previ‐
1459 ously specified in order to restore normal behavior.
1460 errors={continue|remount-ro|panic}
1462 Define the behavior when an error is encountered. (Either ig‐
1463 nore errors and just mark the filesystem erroneous and continue,
1464 or remount the filesystem read-only, or panic and halt the sys‐
1465 tem.)
1466 noquota|quota|usrquota|grpquota
1468 These options are accepted but ignored.
1469 Mount options for msdos
1472 See mount options for fat. If the msdos filesystem detects an incon‐
1473 sistency, it reports an error and sets the file system read-only. The
1474 filesystem can be made writable again by remounting it.
1475 Mount options for ncpfs
1478 Just like nfs, the ncpfs implementation expects a binary argument (a
1479 struct ncp_mount_data) to the mount system call. This argument is con‐
1480 structed by ncpmount(8) and the current version of mount (2.12) does
1481 not know anything about ncpfs.
1482 Mount options for ntfs
1485 iocharset=name
1486 Character set to use when returning file names. Unlike VFAT,
1487 NTFS suppresses names that contain nonconvertible characters.
1488 Deprecated.
1489 nls=name
1491 New name for the option earlier called iocharset.
1492 utf8 Use UTF-8 for converting file names.
1494 uni_xlate={0|1|2}
1496 For 0 (or `no' or `false'), do not use escape sequences for un‐
1497 known Unicode characters. For 1 (or `yes' or `true') or 2, use
1498 vfat-style 4-byte escape sequences starting with ":". Here 2
1499 give a little-endian encoding and 1 a byteswapped bigendian en‐
1500 coding.
1501 posix=[0|1]
1503 If enabled (posix=1), the filesystem distinguishes between upper
1504 and lower case. The 8.3 alias names are presented as hard links
1505 instead of being suppressed. This option is obsolete.
1506 uid=value, gid=value and umask=value
1508 Set the file permission on the filesystem. The umask value is
1509 given in octal. By default, the files are owned by root and not
1510 readable by somebody else.
1511 Mount options for overlay
1514 Since Linux 3.18 the overlay pseudo filesystem implements a union mount
1515 for other filesystems.
1516 An overlay filesystem combines two filesystems - an upper filesystem
1518 and a lower filesystem. When a name exists in both filesystems, the
1519 object in the upper filesystem is visible while the object in the lower
1520 filesystem is either hidden or, in the case of directories, merged with
1521 the upper object.
1522 The lower filesystem can be any filesystem supported by Linux and does
1524 not need to be writable. The lower filesystem can even be another
1525 overlayfs. The upper filesystem will normally be writable and if it is
1526 it must support the creation of trusted.* extended attributes, and must
1527 provide a valid d_type in readdir responses, so NFS is not suitable.
1528 A read-only overlay of two read-only filesystems may use any filesystem
1530 type. The options lowerdir and upperdir are combined into a merged di‐
1531 rectory by using:
1532 mount -t overlay overlay \
1534 -olowerdir=/lower,upperdir=/upper,workdir=/work /merged
1535 lowerdir=directory
1538 Any filesystem, does not need to be on a writable filesystem.
1539 upperdir=directory
1541 The upperdir is normally on a writable filesystem.
1542 workdir=directory
1544 The workdir needs to be an empty directory on the same filesys‐
1545 tem as upperdir.
1546 Mount options for reiserfs
1549 Reiserfs is a journaling filesystem.
1550 conv Instructs version 3.6 reiserfs software to mount a version 3.5
1552 filesystem, using the 3.6 format for newly created objects.
1553 This filesystem will no longer be compatible with reiserfs 3.5
1554 tools.
1555 hash={rupasov|tea|r5|detect}
1557 Choose which hash function reiserfs will use to find files
1558 within directories.
1559 rupasov
1561 A hash invented by Yury Yu. Rupasov. It is fast and pre‐
1562 serves locality, mapping lexicographically close file
1563 names to close hash values. This option should not be
1564 used, as it causes a high probability of hash collisions.
1565 tea A Davis-Meyer function implemented by Jeremy
1567 Fitzhardinge. It uses hash permuting bits in the name.
1568 It gets high randomness and, therefore, low probability
1569 of hash collisions at some CPU cost. This may be used if
1570 EHASHCOLLISION errors are experienced with the r5 hash.
1571 r5 A modified version of the rupasov hash. It is used by
1573 default and is the best choice unless the filesystem has
1574 huge directories and unusual file-name patterns.
1575 detect Instructs mount to detect which hash function is in use
1577 by examining the filesystem being mounted, and to write
1578 this information into the reiserfs superblock. This is
1579 only useful on the first mount of an old format filesys‐
1580 tem.
1581 hashed_relocation
1583 Tunes the block allocator. This may provide performance im‐
1584 provements in some situations.
1585 no_unhashed_relocation
1587 Tunes the block allocator. This may provide performance im‐
1588 provements in some situations.
1589 noborder
1591 Disable the border allocator algorithm invented by Yury Yu. Ru‐
1592 pasov. This may provide performance improvements in some situa‐
1593 tions.
1594 nolog Disable journaling. This will provide slight performance im‐
1596 provements in some situations at the cost of losing reiserfs's
1597 fast recovery from crashes. Even with this option turned on,
1598 reiserfs still performs all journaling operations, save for ac‐
1599 tual writes into its journaling area. Implementation of nolog
1600 is a work in progress.
1601 notail By default, reiserfs stores small files and `file tails' di‐
1603 rectly into its tree. This confuses some utilities such as
1604 LILO(8). This option is used to disable packing of files into
1605 the tree.
1606 replayonly
1608 Replay the transactions which are in the journal, but do not ac‐
1609 tually mount the filesystem. Mainly used by reiserfsck.
1610 resize=number
1612 A remount option which permits online expansion of reiserfs par‐
1613 titions. Instructs reiserfs to assume that the device has num‐
1614 ber blocks. This option is designed for use with devices which
1615 are under logical volume management (LVM). There is a special
1616 resizer utility which can be obtained from
1617 ftp://ftp.namesys.com/pub/reiserfsprogs.
1618 user_xattr
1620 Enable Extended User Attributes. See the attr(1) manual page.
1621 acl Enable POSIX Access Control Lists. See the acl(5) manual page.
1623 barrier=none / barrier=flush
1625 This disables / enables the use of write barriers in the jour‐
1626 naling code. barrier=none disables, barrier=flush enables (de‐
1627 fault). This also requires an IO stack which can support barri‐
1628 ers, and if reiserfs gets an error on a barrier write, it will
1629 disable barriers again with a warning. Write barriers enforce
1630 proper on-disk ordering of journal commits, making volatile disk
1631 write caches safe to use, at some performance penalty. If your
1632 disks are battery-backed in one way or another, disabling barri‐
1633 ers may safely improve performance.
1634 Mount options for ubifs
1637 UBIFS is a flash filesystem which works on top of UBI volumes. Note
1638 that atime is not supported and is always turned off.
1639 The device name may be specified as
1641 ubiX_Y UBI device number X, volume number Y
1643 ubiY UBI device number 0, volume number Y
1645 ubiX:NAME
1647 UBI device number X, volume with name NAME
1648 ubi:NAME
1650 UBI device number 0, volume with name NAME
1651 Alternative ! separator may be used instead of :.
1653 The following mount options are available:
1655 bulk_read
1657 Enable bulk-read. VFS read-ahead is disabled because it slows
1658 down the filesystem. Bulk-Read is an internal optimization.
1659 Some flashes may read faster if the data are read at one go,
1660 rather than at several read requests. For example, OneNAND can
1661 do "read-while-load" if it reads more than one NAND page.
1662 no_bulk_read
1664 Do not bulk-read. This is the default.
1665 chk_data_crc
1667 Check data CRC-32 checksums. This is the default.
1668 no_chk_data_crc.
1670 Do not check data CRC-32 checksums. With this option, the
1671 filesystem does not check CRC-32 checksum for data, but it does
1672 check it for the internal indexing information. This option
1673 only affects reading, not writing. CRC-32 is always calculated
1674 when writing the data.
1675 compr={none|lzo|zlib}
1677 Select the default compressor which is used when new files are
1678 written. It is still possible to read compressed files if
1679 mounted with the none option.
1680 Mount options for udf
1683 UDF is the "Universal Disk Format" filesystem defined by OSTA, the Op‐
1684 tical Storage Technology Association, and is often used for DVD-ROM,
1685 frequently in the form of a hybrid UDF/ISO-9660 filesystem. It is, how‐
1686 ever, perfectly usable by itself on disk drives, flash drives and other
1687 block devices. See also iso9660.
1688 uid= Make all files in the filesystem belong to the given user.
1690 uid=forget can be specified independently of (or usually in ad‐
1691 dition to) uid=<user> and results in UDF not storing uids to the
1692 media. In fact the recorded uid is the 32-bit overflow uid -1 as
1693 defined by the UDF standard. The value is given as either
1694 <user> which is a valid user name or the corresponding decimal
1695 user id, or the special string "forget".
1696 gid= Make all files in the filesystem belong to the given group.
1698 gid=forget can be specified independently of (or usually in ad‐
1699 dition to) gid=<group> and results in UDF not storing gids to
1700 the media. In fact the recorded gid is the 32-bit overflow gid
1701 -1 as defined by the UDF standard. The value is given as either
1702 <group> which is a valid group name or the corresponding decimal
1703 group id, or the special string "forget".
1704 umask= Mask out the given permissions from all inodes read from the
1706 filesystem. The value is given in octal.
1707 mode= If mode= is set the permissions of all non-directory inodes read
1709 from the filesystem will be set to the given mode. The value is
1710 given in octal.
1711 dmode= If dmode= is set the permissions of all directory inodes read
1713 from the filesystem will be set to the given dmode. The value is
1714 given in octal.
1715 bs= Set the block size. Default value prior to kernel version 2.6.30
1717 was 2048. Since 2.6.30 and prior to 4.11 it was logical device
1718 block size with fallback to 2048. Since 4.11 it is logical block
1719 size with fallback to any valid block size between logical de‐
1720 vice block size and 4096.
1721 For other details see the mkudffs(8) 2.0+ manpage, sections COM‐
1723 PATIBILITY and BLOCK SIZE.
1724 unhide Show otherwise hidden files.
1726 undelete
1728 Show deleted files in lists.
1729 adinicb
1731 Embed data in the inode. (default)
1732 noadinicb
1734 Don't embed data in the inode.
1735 shortad
1737 Use short UDF address descriptors.
1738 longad Use long UDF address descriptors. (default)
1740 nostrict
1742 Unset strict conformance.
1743 iocharset=
1745 Set the NLS character set. This requires kernel compiled with
1746 CONFIG_UDF_NLS option.
1747 utf8 Set the UTF-8 character set.
1749 Mount options for debugging and disaster recovery
1751 novrs Ignore the Volume Recognition Sequence and attempt to mount any‐
1752 way.
1753 session=
1755 Select the session number for multi-session recorded optical me‐
1756 dia. (default= last session)
1757 anchor=
1759 Override standard anchor location. (default= 256)
1760 lastblock=
1762 Set the last block of the filesystem.
1763 Unused historical mount options that may be encountered and should be re‐
1765 moved
1766 uid=ignore
1767 Ignored, use uid=<user> instead.
1768 gid=ignore
1770 Ignored, use gid=<group> instead.
1771 volume=
1773 Unimplemented and ignored.
1774 partition=
1776 Unimplemented and ignored.
1777 fileset=
1779 Unimplemented and ignored.
1780 rootdir=
1782 Unimplemented and ignored.
1783 Mount options for ufs
1786 ufstype=value
1787 UFS is a filesystem widely used in different operating systems.
1788 The problem are differences among implementations. Features of
1789 some implementations are undocumented, so its hard to recognize
1790 the type of ufs automatically. That's why the user must specify
1791 the type of ufs by mount option. Possible values are:
1792 old Old format of ufs, this is the default, read only.
1794 (Don't forget to give the -r option.)
1795 44bsd For filesystems created by a BSD-like system (NetBSD,
1797 FreeBSD, OpenBSD).
1798 ufs2 Used in FreeBSD 5.x supported as read-write.
1800 5xbsd Synonym for ufs2.
1802 sun For filesystems created by SunOS or Solaris on Sparc.
1804 sunx86 For filesystems created by Solaris on x86.
1806 hp For filesystems created by HP-UX, read-only.
1808 nextstep
1810 For filesystems created by NeXTStep (on NeXT station)
1811 (currently read only).
1812 nextstep-cd
1814 For NextStep CDROMs (block_size == 2048), read-only.
1815 openstep
1817 For filesystems created by OpenStep (currently read
1818 only). The same filesystem type is also used by Mac OS
1819 X.
1820 onerror=value
1823 Set behavior on error:
1824 panic If an error is encountered, cause a kernel panic.
1826 [lock|umount|repair]
1828 These mount options don't do anything at present; when an
1829 error is encountered only a console message is printed.
1830 Mount options for umsdos
1833 See mount options for msdos. The dotsOK option is explicitly killed by
1834 umsdos.
1835 Mount options for vfat
1838 First of all, the mount options for fat are recognized. The dotsOK op‐
1839 tion is explicitly killed by vfat. Furthermore, there are
1840 uni_xlate
1842 Translate unhandled Unicode characters to special escaped se‐
1843 quences. This lets you backup and restore filenames that are
1844 created with any Unicode characters. Without this option, a '?'
1845 is used when no translation is possible. The escape character
1846 is ':' because it is otherwise invalid on the vfat filesystem.
1847 The escape sequence that gets used, where u is the Unicode char‐
1848 acter, is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).
1849 posix Allow two files with names that only differ in case. This op‐
1851 tion is obsolete.
1852 nonumtail
1854 First try to make a short name without sequence number, before
1855 trying name~num.ext.
1856 utf8 UTF8 is the filesystem safe 8-bit encoding of Unicode that is
1858 used by the console. It can be enabled for the filesystem with
1859 this option or disabled with utf8=0, utf8=no or utf8=false. If
1860 `uni_xlate' gets set, UTF8 gets disabled.
1861 shortname=mode
1863 Defines the behavior for creation and display of filenames which
1864 fit into 8.3 characters. If a long name for a file exists, it
1865 will always be the preferred one for display. There are four
1866 modes:
1867 lower Force the short name to lower case upon display; store a
1869 long name when the short name is not all upper case.
1870 win95 Force the short name to upper case upon display; store a
1872 long name when the short name is not all upper case.
1873 winnt Display the short name as is; store a long name when the
1875 short name is not all lower case or all upper case.
1876 mixed Display the short name as is; store a long name when the
1878 short name is not all upper case. This mode is the de‐
1879 fault since Linux 2.6.32.
1880 Mount options for usbfs
1883 devuid=uid and devgid=gid and devmode=mode
1884 Set the owner and group and mode of the device files in the us‐
1885 bfs filesystem (default: uid=gid=0, mode=0644). The mode is
1886 given in octal.
1887 busuid=uid and busgid=gid and busmode=mode
1889 Set the owner and group and mode of the bus directories in the
1890 usbfs filesystem (default: uid=gid=0, mode=0555). The mode is
1891 given in octal.
1892 listuid=uid and listgid=gid and listmode=mode
1894 Set the owner and group and mode of the file devices (default:
1895 uid=gid=0, mode=0444). The mode is given in octal.
1896
1899 The device-mapper verity target provides read-only transparent integ‐
1900 rity checking of block devices using kernel crypto API. The mount com‐
1901 mand can open the dm-verity device and do the integrity verification
1902 before on the device filesystem is mounted. Requires libcryptsetup
1903 with in libmount (optionally via dlopen). If libcryptsetup supports
1904 extracting the root hash of an already mounted device, existing devices
1905 will be automatically reused in case of a match. Mount options for dm-
1906 verity:
1907 verity.hashdevice=path
1909 Path to the hash tree device associated with the source volume
1910 to pass to dm-verity.
1911 verity.roothash=hex
1913 Hex-encoded hash of the root of verity.hashdevice Mutually ex‐
1914 clusive with verity.roothashfile.
1915 verity.roothashfile=path
1917 Path to file containing the hex-encoded hash of the root of ver‐
1918 ity.hashdevice. Mutually exclusive with verity.roothash.
1919 verity.hashoffset=offset
1921 If the hash tree device is embedded in the source volume, offset
1922 (default: 0) is used by dm-verity to get to the tree.
1923 verity.fecdevice=path
1925 Path to the Forward Error Correction (FEC) device associated
1926 with the source volume to pass to dm-verity. Optional. Requires
1927 kernel built with CONFIG_DM_VERITY_FEC.
1928 verity.fecoffset=offset
1930 If the FEC device is embedded in the source volume, offset (de‐
1931 fault: 0) is used by dm-verity to get to the FEC area. Optional.
1932 verity.fecroots=value
1934 Parity bytes for FEC (default: 2). Optional.
1935 verity.roothashsig=path
1937 Path to pkcs7 signature of root hash hex string. Requires
1938 crypt_activate_by_signed_key() from cryptsetup and kernel built
1939 with CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG. For device reuse,
1940 signatures have to be either used by all mounts of a device or
1941 by none. Optional.
1942 Supported since util-linux v2.35.
1944 For example commands:
1946 mksquashfs /etc /tmp/etc.squashfs
1948 dd if=/dev/zero of=/tmp/etc.hash bs=1M count=10
1949 veritysetup format /tmp/etc.squashfs /tmp/etc.hash
1950 openssl smime -sign -in <hash> -nocerts -inkey private.key \
1951 -signer private.crt -noattr -binary -outform der -out /tmp/etc.p7
1952 mount -o verity.hashdevice=/tmp/etc.hash,verity.roothash=<hash>,\
1953 verity.roothashsig=/tmp/etc.p7 /tmp/etc.squashfs /mnt
1954 create squashfs image from /etc directory, verity hash device and mount
1956 verified filesystem image to /mnt. The kernel will verify that the
1957 root hash is signed by a key from the kernel keyring if roothashsig is
1958 used.
1959
1962 One further possible type is a mount via the loop device. For example,
1963 the command
1964 mount /tmp/disk.img /mnt -t vfat -o loop=/dev/loop3
1966 will set up the loop device /dev/loop3 to correspond to the file
1968 /tmp/disk.img, and then mount this device on /mnt.
1969 If no explicit loop device is mentioned (but just an option `-o loop'
1971 is given), then mount will try to find some unused loop device and use
1972 that, for example
1973 mount /tmp/disk.img /mnt -o loop
1975 The mount command automatically creates a loop device from a regular
1977 file if a filesystem type is not specified or the filesystem is known
1978 for libblkid, for example:
1979 mount /tmp/disk.img /mnt
1981 mount -t ext4 /tmp/disk.img /mnt
1983 This type of mount knows about three options, namely loop, offset and
1985 sizelimit, that are really options to losetup(8). (These options can
1986 be used in addition to those specific to the filesystem type.)
1987 Since Linux 2.6.25 auto-destruction of loop devices is supported, mean‐
1989 ing that any loop device allocated by mount will be freed by umount in‐
1990 dependently of /etc/mtab.
1991 You can also free a loop device by hand, using losetup -d or umount -d.
1993 Since util-linux v2.29, mount re-uses the loop device rather than ini‐
1995 tializing a new device if the same backing file is already used for
1996 some loop device with the same offset and sizelimit. This is necessary
1997 to avoid a filesystem corruption.
1998
2001 mount has the following exit status values (the bits can be ORed):
2002 0 success
2004 1 incorrect invocation or permissions
2006 2 system error (out of memory, cannot fork, no more loop devices)
2008 4 internal mount bug
2010 8 user interrupt
2012 16 problems writing or locking /etc/mtab
2014 32 mount failure
2016 64 some mount succeeded
2018 The command mount -a returns 0 (all succeeded), 32 (all failed),
2020 or 64 (some failed, some succeeded).
2021
2024 The syntax of external mount helpers is:
2025 /sbin/mount.suffix spec dir [-sfnv] [-N namespace] [-o options] [-t
2027 type.subtype]
2028 where the suffix is the filesystem type and the -sfnvoN options have
2030 the same meaning as the normal mount options. The -t option is used
2031 for filesystems with subtypes support (for example /sbin/mount.fuse -t
2032 fuse.sshfs).
2033 The command mount does not pass the mount options unbindable, runbind‐
2035 able, private, rprivate, slave, rslave, shared, rshared, auto, noauto,
2036 comment, x-*, loop, offset and sizelimit to the mount.<suffix> helpers.
2037 All other options are used in a comma-separated list as an argument to
2038 the -o option.
2039
2042 LIBMOUNT_FSTAB=<path>
2043 overrides the default location of the fstab file (ignored for
2044 suid)
2045 LIBMOUNT_MTAB=<path>
2047 overrides the default location of the mtab file (ignored for
2048 suid)
2049 LIBMOUNT_DEBUG=all
2051 enables libmount debug output
2052 LIBBLKID_DEBUG=all
2054 enables libblkid debug output
2055 LOOPDEV_DEBUG=all
2057 enables loop device setup debug output
2058
2060 See also "The files /etc/fstab, /etc/mtab and /proc/mounts" section
2061 above.
2062 /etc/fstab filesystem table
2064 /run/mount libmount private runtime directory
2066 /etc/mtab table of mounted filesystems or symlink to
2068 /proc/mounts
2069 /etc/mtab~ lock file (unused on systems with mtab symlink)
2071 /etc/mtab.tmp temporary file (unused on systems with mtab symlink)
2073 /etc/filesystems a list of filesystem types to try
2075
2077 A mount command existed in Version 5 AT&T UNIX.
2078
2080 It is possible for a corrupted filesystem to cause a crash.
2081 Some Linux filesystems don't support -o sync and -o dirsync (the ext2,
2083 ext3, ext4, fat and vfat filesystems do support synchronous updates (a
2084 la BSD) when mounted with the sync option).
2085 The -o remount may not be able to change mount parameters (all ext2fs-
2087 specific parameters, except sb, are changeable with a remount, for ex‐
2088 ample, but you can't change gid or umask for the fatfs).
2089 It is possible that the files /etc/mtab and /proc/mounts don't match on
2091 systems with a regular mtab file. The first file is based only on the
2092 mount command options, but the content of the second file also depends
2093 on the kernel and others settings (e.g. on a remote NFS server -- in
2094 certain cases the mount command may report unreliable information about
2095 an NFS mount point and the /proc/mount file usually contains more reli‐
2096 able information.) This is another reason to replace the mtab file
2097 with a symlink to the /proc/mounts file.
2098 Checking files on NFS filesystems referenced by file descriptors (i.e.
2100 the fcntl and ioctl families of functions) may lead to inconsistent re‐
2101 sults due to the lack of a consistency check in the kernel even if the
2102 noac mount option is used.
2103 The loop option with the offset or sizelimit options used may fail when
2105 using older kernels if the mount command can't confirm that the size of
2106 the block device has been configured as requested. This situation can
2107 be worked around by using the losetup command manually before calling
2108 mount with the configured loop device.
2109
2111 Karel Zak <kzak@redhat.com>
2112
2114 lsblk(1), mount(2), umount(2), filesystems(5), fstab(5), nfs(5),
2115 xfs(5), mount_namespaces(7) xattr(7) e2label(8), findmnt(8), los‐
2116 etup(8), mke2fs(8), mountd(8), nfsd(8), swapon(8), tune2fs(8),
2117 umount(8), xfs_admin(8)
2118
2120 The mount command is part of the util-linux package and is available
2121 from https://www.kernel.org/pub/linux/utils/util-linux/.
2122util-linux August 2015 MOUNT(8)