1 .\" Copyright (c) 1996-2004 Andries Brouwer
3 .\" This page is somewhat derived from a page that was
4 .\" (c) 1980, 1989, 1991 The Regents of the University of California
5 .\" and had been heavily modified by Rik Faith and myself.
6 .\" (Probably no BSD text remains.)
7 .\" Fragments of text were written by Werner Almesberger, Remy Card,
8 .\" Stephen Tweedie and Eric Youngdale.
10 .\" This is free documentation; you can redistribute it and/or
11 .\" modify it under the terms of the GNU General Public License as
12 .\" published by the Free Software Foundation; either version 2 of
13 .\" the License, or (at your option) any later version.
15 .\" The GNU General Public License's references to "object code"
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20 .\" This manual is distributed in the hope that it will be useful,
21 .\" but WITHOUT ANY WARRANTY; without even the implied warranty of
22 .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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25 .\" You should have received a copy of the GNU General Public
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27 .\" Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
30 .\" 960705, aeb: version for mount-2.7g
31 .\" 970114, aeb: xiafs and ext are dead; romfs is new
32 .\" 970623, aeb: -F option
33 .\" 970914, reg: -s option
34 .\" 981111, K.Garloff: /etc/filesystems
35 .\" 990111, aeb: documented /sbin/mount.smbfs
36 .\" 990730, Yann Droneaud <lch@multimania.com>: updated page
37 .\" 991214, Elrond <Elrond@Wunder-Nett.org>: added some docs on devpts
38 .\" 010714, Michael K. Johnson <johnsonm@redhat.com> added -O
39 .\" 010725, Nikita Danilov <NikitaDanilov@Yahoo.COM>: reiserfs options
40 .\" 011124, Karl Eichwalder <ke@gnu.franken.de>: tmpfs options
42 .TH MOUNT 8 "2004-12-16" "Linux 2.6" "Linux Programmer's Manual"
44 mount \- mount a filesystem
59 .IR option [ \fB,\fPoption ]...]
70 All files accessible in a Unix system are arranged in one big
71 tree, the file hierarchy, rooted at
73 These files can be spread out over several devices. The
75 command serves to attach the filesystem found on some device
76 to the big file tree. Conversely, the
78 command will detach it again.
80 The standard form of the
86 .BI "mount \-t" " type device dir"
90 This tells the kernel to attach the filesystem found on
96 The previous contents (if any) and owner and mode of
98 become invisible, and as long as this filesystem remains mounted,
101 refers to the root of the filesystem on
104 .B The listing and help.
106 Three forms of invocation do not actually mount anything:
109 prints a help message
112 prints a version string
114 .BR "mount " [ -l "] [" "-t \fItype\fP" ]
115 lists all mounted filesystems (of type
117 The option \-l adds the labels in this listing.
123 .\" In fact since 2.3.99. At first the syntax was mount -t bind.
124 Since Linux 2.4.0 it is possible to remount part of the
125 file hierarchy somewhere else. The call is
145 After this call the same contents is accessible in two places.
146 One can also remount a single file (on a single file).
148 This call attaches only (part of) a single filesystem, not possible
149 submounts. The entire file hierarchy including submounts is attached
162 .\" available since Linux 2.4.11.
164 Note that the filesystem mount options will remain the same as those
165 on the original mount point, and cannot be changed by passing the -o
166 option along with --bind/--rbind.
169 .B The move operation.
171 Since Linux 2.5.1 it is possible to atomically move a mounted tree
172 to another place. The call is
186 .B The shared subtrees operations.
188 Since Linux 2.6.15 it is possible to mark a mount and its submounts as shared,
189 private, slave or unbindable. A shared mount provides ability to create mirrors
190 of that mount such that mounts and umounts within any of the mirrors propagate
191 to the other mirror. A slave mount receives propagation from its master, but
192 any not vice-versa. A private mount carries no propagation abilities. A
193 unbindable mount is a private mount which cannot cloned through a bind
194 operation. Detailed semantics is documented in Documentation/sharedsubtree.txt
195 file in the kernel source tree.
199 .BI "mount --make-shared " mountpoint
200 .BI "mount --make-slave " mountpoint
201 .BI "mount --make-private " mountpoint
202 .BI "mount --make-unbindable " mountpoint
206 The following commands allows one to recursively change the type of all the
207 mounts under a given mountpoint.
211 .BI "mount --make-rshared " mountpoint
212 .BI "mount --make-rslave " mountpoint
213 .BI "mount --make-rprivate " mountpoint
214 .BI "mount --make-runbindable " mountpoint
219 .B The device indication.
221 Most devices are indicated by a file name (of a block special device), like
223 but there are other possibilities. For example, in the case of an NFS mount,
226 .IR knuth.cwi.nl:/dir .
227 It is possible to indicate a block special device using its
232 (see the \-L and \-U options below).
236 filesystem is not associated with a special device, and when
237 mounting it, an arbitrary keyword, such as
239 can be used instead of a device specification.
240 (The customary choice
242 is less fortunate: the error message `none busy' from
247 .B The /etc/fstab, /etc/mtab and /proc/mounts files.
253 may contain lines describing what devices are usually
254 mounted where, using which options.
266 (usually given in a bootscript) causes all filesystems mentioned in
268 (of the proper type and/or having or not having the proper options)
269 to be mounted as indicated, except for those whose line contains the
273 option will make mount fork, so that the
274 filesystems are mounted simultaneously.
276 When mounting a filesystem mentioned in
280 it suffices to give only the device, or only the mount point.
287 maintain a list of currently mounted filesystems in the file
289 If no arguments are given to
291 this list is printed.
295 filesystem is mounted (say at
301 have very similar contents. The former has somewhat
302 more information, such as the mount options used,
303 but is not necessarily up-to-date (cf. the
305 option below). It is possible to replace
307 by a symbolic link to
309 and especially when you have very large numbers of mounts
310 things will be much faster with that symlink,
311 but some information is lost that way, and in particular
312 working with the loop device will be less convenient,
313 and using the "user" option will fail.
316 .B The non-superuser mounts.
318 Normally, only the superuser can mount filesystems.
323 option on a line, anybody can mount the corresponding system.
328 .B "/dev/cdrom /cd iso9660 ro,user,noauto,unhide"
331 any user can mount the iso9660 filesystem found on his CDROM
335 .B "mount /dev/cdrom"
344 For more details, see
346 Only the user that mounted a filesystem can unmount it again.
347 If any user should be able to unmount, then use
356 option is similar to the
358 option, with the restriction that the user must be the owner
359 of the special file. This may be useful e.g. for
361 if a login script makes the console user owner of this device.
364 option is similar, with the restriction that the user must be
365 member of the group of the special file.
368 .SH COMMAND LINE OPTIONS
369 The full set of mount options used by an invocation of
371 is determined by first extracting the
372 mount options for the filesystem from the
374 table, then applying any options specified by the
376 argument, and finally applying a
378 option, when present.
380 Command line options available for the
388 Print a help message.
394 Mount all filesystems (of the given types) mentioned in
398 (Used in conjunction with
400 Fork off a new incarnation of mount for each device.
401 This will do the mounts on different devices or different NFS servers
403 This has the advantage that it is faster; also NFS timeouts go in
404 parallel. A disadvantage is that the mounts are done in undefined order.
405 Thus, you cannot use this option if you want to mount both
411 Causes everything to be done except for the actual system call; if it's not
412 obvious, this ``fakes'' mounting the filesystem. This option is useful in
415 flag to determine what the
417 command is trying to do. It can also be used to add entries for devices
418 that were mounted earlier with the -n option. The -f option checks for
419 existing record in /etc/mtab and fails when the record already
420 exists (with regular non-fake mount, this check is done by kernel).
423 Don't call the /sbin/mount.<filesystem> helper even if it exists.
426 Add the labels in the mount output. Mount must have
427 permission to read the disk device (e.g. be suid root) for this to work.
428 One can set such a label for ext2, ext3 or ext4 using the
430 utility, or for XFS using
432 or for reiserfs using
433 .BR reiserfstune (8).
436 Mount without writing in
438 This is necessary for example when
440 is on a read-only filesystem.
443 In case of a loop mount with encryption, read the passphrase from
446 instead of from the terminal.
449 Tolerate sloppy mount options rather than failing. This will ignore
450 mount options not supported by a filesystem type. Not all filesystems
451 support this option. This option exists for support of the Linux
452 autofs\-based automounter.
455 Mount the filesystem read-only. A synonym is
458 Note that, depending on the filesystem type, state and kernel behavior, the
459 system may still write to the device. For example, Ext3 or ext4 will replay its
460 journal if the filesystem is dirty. To prevent this kind of write access, you
461 may want to mount ext3 or ext4 filesystem with "ro,noload" mount options or
462 set the block device to read-only mode, see command
466 Mount the filesystem read/write. This is the default. A synonym is
470 Mount the partition that has the specified
474 Mount the partition that has the specified
476 These two options require the file
478 (present since Linux 2.1.116) to exist.
481 The argument following the
483 is used to indicate the filesystem type. The filesystem types which are
484 currently supported include:
526 Note that coherent, sysv and xenix are equivalent and that
530 will be removed at some point in the future \(em use
532 instead. Since kernel version 2.1.21 the types
536 do not exist anymore. Earlier,
540 Note, the real list of all supported filesystems depends on your
543 For most types all the
545 program has to do is issue a simple
547 system call, and no detailed knowledge of the filesystem type is required.
548 For a few types however (like nfs, nfs4, cifs, smbfs, ncpfs) ad hoc code is
549 necessary. The nfs, nfs4, cifs, smbfs, and ncpfs filesystems
550 have a separate mount program. In order to make it possible to
551 treat all types in a uniform way, mount will execute the program
552 .BI /sbin/mount. TYPE
553 (if that exists) when called with type
555 Since various versions of the
557 program have different calling conventions,
559 may have to be a shell script that sets up the desired call.
563 option is given, or if the
565 type is specified, mount will try to guess the desired type.
566 Mount uses the blkid or volume_id library for guessing the filesystem
567 type; if that does not turn up anything that looks familiar,
568 mount will try to read the file
569 .IR /etc/filesystems ,
570 or, if that does not exist,
571 .IR /proc/filesystems .
572 All of the filesystem types listed there will be tried,
573 except for those that are labeled "nodev" (e.g.,
580 ends in a line with a single * only, mount will read
586 type may be useful for user-mounted floppies.
589 can be useful to change the probe order (e.g., to try vfat before msdos
590 or ext3 before ext2) or if you use a kernel module autoloader.
591 Warning: the probing uses a heuristic (the presence of appropriate `magic'),
592 and could recognize the wrong filesystem type, possibly with catastrophic
593 consequences. If your data is valuable, don't ask
597 More than one type may be specified in a comma separated
598 list. The list of filesystem types can be prefixed with
600 to specify the filesystem types on which no action should be taken.
601 (This can be meaningful with the
605 For example, the command:
608 .B "mount \-a \-t nomsdos,ext"
610 mounts all filesystems except those of type
617 Used in conjunction with
619 to limit the set of filesystems to which the
623 in this regard except that it is useless except in the context of
625 For example, the command:
629 .B "mount \-a \-O no_netdev"
632 mounts all filesystems except those which have the option
634 specified in the options field in the
640 in that each option is matched exactly; a leading
642 at the beginning of one option does not negate the rest.
648 options are cumulative in effect; that is, the command
651 .B "mount \-a \-t ext2 \-O _netdev"
654 mounts all ext2 filesystems with the _netdev option, not all filesystems
655 that are either ext2 or have the _netdev option specified.
659 Options are specified with a
661 flag followed by a comma separated string of options. For example:
664 .B "mount LABEL=mydisk \-o noatime,nouser"
667 For more details, see
668 .B FILESYSTEM INDEPENDENT MOUNT OPTIONS
670 .B FILESYSTEM SPECIFIC MOUNT OPTIONS
675 Remount a subtree somewhere else (so that its contents are available
676 in both places). See above.
679 Remount a subtree and all possible submounts somewhere else (so that its
680 contents are available in both places). See above.
683 Move a subtree to some other place. See above.
686 .SH FILESYSTEM INDEPENDENT MOUNT OPTIONS
687 Some of these options are only useful when they appear in the
691 Some of these options could be enabled or disabled by default
692 in the system kernel. To check the current setting see the options
695 The following options apply to any filesystem that is being
696 mounted (but not every filesystem actually honors them - e.g., the
698 option today has effect only for ext2, ext3, fat, vfat and ufs):
702 All I/O to the filesystem should be done asynchronously. (See also the
707 Update inode access time for each access. See also the
712 Do not update inode access times on this filesystem (e.g, for faster
713 access on the news spool to speed up news servers).
716 Can be mounted with the
721 Can only be mounted explicitly (i.e., the
723 option will not cause the filesystem to be mounted).
725 \fBcontext=\fP\fIcontext\fP, \fBfscontext=\fP\fIcontext\fP, \fBdefcontext=\fP\fIcontext\fP and \fBrootcontext=\fP\fIcontext\fP
728 option is useful when mounting filesystems that do not support
729 extended attributes, such as a floppy or hard disk formatted with VFAT, or
730 systems that are not normally running under SELinux, such as an ext3 formatted
731 disk from a non-SELinux workstation. You can also use
733 on filesystems you do not trust, such as a floppy. It also helps in compatibility with
734 xattr-supporting filesystems on earlier 2.4.<x> kernel versions. Even where
735 xattrs are supported, you can save time not having to label every file by
736 assigning the entire disk one security context.
738 A commonly used option for removable media is
739 .BR context=system_u:object_r:removable_t .
741 Two other options are
745 both of which are mutually exclusive of the context option. This means you
746 can use fscontext and defcontext with each other, but neither can be used with
751 option works for all filesystems, regardless of their xattr
752 support. The fscontext option sets the overarching filesystem label to a
753 specific security context. This filesystem label is separate from the
754 individual labels on the files. It represents the entire filesystem for
755 certain kinds of permission checks, such as during mount or file creation.
756 Individual file labels are still obtained from the xattrs on the files
757 themselves. The context option actually sets the aggregate context that
758 fscontext provides, in addition to supplying the same label for individual
761 You can set the default security context for unlabeled files using
763 option. This overrides the value set for unlabeled files in the policy and requires a
764 filesystem that supports xattr labeling.
768 option allows you to explicitly label the root inode of a FS being mounted
769 before that FS or inode because visable to userspace. This was found to be
770 useful for things like stateless linux.
772 For more details, see
778 .BR rw ", " suid ", " dev ", " exec ", " auto ", " nouser ", and " async.
781 Interpret character or block special devices on the filesystem.
784 Do not interpret character or block special devices on the file
788 Update directory inode access times on this filesystem. This is the default.
791 Do not update directory inode access times on this filesystem.
794 All directory updates within the filesystem should be done synchronously.
795 This affects the following system calls: creat, link, unlink, symlink,
796 mkdir, rmdir, mknod and rename.
799 Permit execution of binaries.
802 Do not allow direct execution of any binaries on the mounted filesystem.
803 (Until recently it was possible to run binaries anyway using a command like
804 /lib/ld*.so /mnt/binary. This trick fails since Linux 2.4.25 / 2.6.0.)
807 Allow an ordinary (i.e., non-root) user to mount the filesystem if one
808 of his groups matches the group of the device.
809 This option implies the options
810 .BR nosuid " and " nodev
811 (unless overridden by subsequent options, as in the option line
812 .BR group,dev,suid ).
815 Every time the inode is modified, the i_version field will be incremented.
818 Do not increment the i_version inode field.
821 Allow mandatory locks on this filesystem. See
825 Do not allow mandatory locks on this filesystem.
828 The filesystem resides on a device that requires network access
829 (used to prevent the system from attempting to mount these filesystems
830 until the network has been enabled on the system).
833 Do not report errors for this device if it does not exist.
836 Update inode access times relative to modify or change time. Access
837 time is only updated if the previous access time was earlier than the
838 current modify or change time. (Similar to noatime, but doesn't break
839 mutt or other applications that need to know if a file has been read
840 since the last time it was modified.)
845 feature. See also the
850 Allows to explicitly requesting full atime updates. This makes it
851 possible for kernel to defaults to
855 but still allow userspace to override it. For more details about the default
856 system mount options see /proc/mounts.
859 Use the kernel's default behaviour for inode access time updates.
862 Allow set-user-identifier or set-group-identifier bits to take
866 Do not allow set-user-identifier or set-group-identifier bits to take
867 effect. (This seems safe, but is in fact rather unsafe if you have
868 suidperl(1) installed.)
871 Allow an ordinary (i.e., non-root) user to mount the filesystem if he
872 is the owner of the device.
873 This option implies the options
874 .BR nosuid " and " nodev
875 (unless overridden by subsequent options, as in the option line
876 .BR owner,dev,suid ).
879 Attempt to remount an already-mounted filesystem. This is commonly
880 used to change the mount flags for a filesystem, especially to make a
881 readonly filesystem writeable. It does not change device or mount point.
883 The remount functionality follows the standard way how the mount command works
884 with options from fstab. It means the mount command doesn't read fstab (or
891 .BR "mount -o remount,rw /dev/foo /dir"
893 After this call all old mount options are replaced and arbitrary stuff from
894 fstab is ignored, except the loop= option which is internally generated and
895 maintained by the mount command.
897 .BR "mount -o remount,rw /dir"
899 After this call mount reads fstab (or mtab) and merges these options with
900 options from command line (
905 Mount the filesystem read-only.
908 Mount the filesystem read-write.
911 All I/O to the filesystem should be done synchronously. In case of media with limited number of write cycles
912 (e.g. some flash drives) "sync" may cause life-cycle shortening.
915 Allow an ordinary user to mount the filesystem.
916 The name of the mounting user is written to mtab so that he can unmount
917 the filesystem again.
918 This option implies the options
919 .BR noexec ", " nosuid ", and " nodev
920 (unless overridden by subsequent options, as in the option line
921 .BR user,exec,dev,suid ).
924 Forbid an ordinary (i.e., non-root) user to mount the filesystem.
928 Allow every user to mount and unmount the filesystem.
929 This option implies the options
930 .BR noexec ", " nosuid ", and " nodev
931 (unless overridden by subsequent options, as in the option line
932 .BR users,exec,dev,suid ).
934 .SH "FILESYSTEM SPECIFIC MOUNT OPTIONS"
935 The following options apply only to certain filesystems.
936 We sort them by filesystem. They all follow the
940 What options are supported depends a bit on the running kernel.
941 More info may be found in the kernel source subdirectory
942 .IR Documentation/filesystems .
944 .SH "Mount options for adfs"
946 \fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP
947 Set the owner and group of the files in the filesystem (default: uid=gid=0).
949 \fBownmask=\fP\fIvalue\fP and \fBothmask=\fP\fIvalue\fP
950 Set the permission mask for ADFS 'owner' permissions and 'other' permissions,
951 respectively (default: 0700 and 0077, respectively).
953 .IR /usr/src/linux/Documentation/filesystems/adfs.txt .
954 .SH "Mount options for affs"
956 \fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP
957 Set the owner and group of the root of the filesystem (default: uid=gid=0,
962 without specified value, the uid and gid of the current process are taken).
964 \fBsetuid=\fP\fIvalue\fP and \fBsetgid=\fP\fIvalue\fP
965 Set the owner and group of all files.
968 Set the mode of all files to
970 disregarding the original permissions.
971 Add search permission to directories that have read permission.
972 The value is given in octal.
975 Do not allow any changes to the protection bits on the filesystem.
978 Set uid and gid of the root of the filesystem to the uid and gid
979 of the mount point upon the first sync or umount, and then
980 clear this option. Strange...
983 Print an informational message for each successful mount.
986 Prefix used before volume name, when following a link.
989 Prefix (of length at most 30) used before '/' when following a symbolic link.
992 (Default: 2.) Number of unused blocks at the start of the device.
995 Give explicitly the location of the root block.
998 Give blocksize. Allowed values are 512, 1024, 2048, 4096.
1000 .BR grpquota | noquota | quota | usrquota
1001 These options are accepted but ignored.
1002 (However, quota utilities may react to such strings in
1005 .SH "Mount options for cifs"
1006 See the options section of the
1008 man page (cifs-mount package must be installed).
1010 .SH "Mount options for coherent"
1013 .SH "Mount options for debugfs"
1014 The debugfs filesystem is a pseudo filesystem, traditionally mounted on
1015 .IR /sys/kernel/debug .
1017 .\" present since 2.6.11
1018 There are no mount options.
1020 .SH "Mount options for devpts"
1021 The devpts filesystem is a pseudo filesystem, traditionally mounted on
1023 In order to acquire a pseudo terminal, a process opens
1025 the number of the pseudo terminal is then made available to the process
1026 and the pseudo terminal slave can be accessed as
1027 .IR /dev/pts/ <number>.
1029 \fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP
1030 This sets the owner or the group of newly created PTYs to
1031 the specified values. When nothing is specified, they will
1032 be set to the UID and GID of the creating process.
1033 For example, if there is a tty group with GID 5, then
1035 will cause newly created PTYs to belong to the tty group.
1038 Set the mode of newly created PTYs to the specified value.
1039 The default is 0600.
1044 makes "mesg y" the default on newly created PTYs.
1047 Create a private instance of devpts filesystem, such that
1048 indices of ptys allocated in this new instance are
1049 independent of indices created in other instances of devpts.
1051 All mounts of devpts without this
1053 option share the same set of pty indices (i.e legacy mode).
1054 Each mount of devpts with the
1056 option has a private set of pty indices.
1058 This option is mainly used to support containers in the
1059 linux kernel. It is implemented in linux kernel versions
1060 starting with 2.6.29. Further, this mount option is valid
1061 only if CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the
1062 kernel configuration.
1064 To use this option effectively,
1066 must be a symbolic link to
1069 .IR Documentation/filesystems/devpts.txt
1070 in the linux kernel source tree for details.
1074 Set the mode for the new
1076 device node in the devpts filesystem.
1078 With the support for multiple instances of devpts (see
1080 option above), each instance has a private
1082 node in the root of the devpts filesystem (typically
1085 For compatibility with older versions of the kernel, the
1086 default mode of the new
1090 specifies a more useful mode for the
1092 node and is highly recommended when the
1094 option is specified.
1096 This option is only implemented in linux kernel versions
1097 starting with 2.6.29. Further this option is valid only if
1098 CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the kernel
1101 .SH "Mount options for ext"
1103 Note that the `ext' filesystem is obsolete. Don't use it.
1104 Since Linux version 2.1.21 extfs is no longer part of the kernel source.
1106 .SH "Mount options for ext2"
1107 The `ext2' filesystem is the standard Linux filesystem.
1108 .\" Due to a kernel bug, it may be mounted with random mount options
1109 .\" (fixed in Linux 2.0.4).
1110 Since Linux 2.5.46, for most mount options the default
1111 is determined by the filesystem superblock. Set them with
1115 Support POSIX Access Control Lists (or not).
1116 .\" requires CONFIG_EXT2_FS_POSIX_ACL
1119 Set the behaviour for the
1123 behaviour is to return in the
1125 field the total number of blocks of the filesystem, while the
1127 behaviour (which is the default) is to subtract the overhead blocks
1128 used by the ext2 filesystem and not available for file storage. Thus
1131 % mount /k -o minixdf; df /k; umount /k
1132 Filesystem 1024-blocks Used Available Capacity Mounted on
1133 /dev/sda6 2630655 86954 2412169 3% /k
1134 % mount /k -o bsddf; df /k; umount /k
1135 Filesystem 1024-blocks Used Available Capacity Mounted on
1136 /dev/sda6 2543714 13 2412169 0% /k
1139 (Note that this example shows that one can add command line options
1140 to the options given in
1144 .BR check= { none | nocheck }
1145 No checking is done at mount time. This is the default. This is fast.
1146 It is wise to invoke
1148 every now and then, e.g. at boot time.
1151 Print debugging info upon each (re)mount.
1153 .BR errors= { continue | remount-ro | panic }
1154 Define the behaviour when an error is encountered.
1155 (Either ignore errors and just mark the filesystem erroneous and continue,
1156 or remount the filesystem read-only, or panic and halt the system.)
1157 The default is set in the filesystem superblock, and can be
1161 .BR grpid | bsdgroups " and " nogrpid | sysvgroups
1162 These options define what group id a newly created file gets.
1165 is set, it takes the group id of the directory in which it is created;
1166 otherwise (the default) it takes the fsgid of the current process, unless
1167 the directory has the setgid bit set, in which case it takes the gid
1168 from the parent directory, and also gets the setgid bit set
1169 if it is a directory itself.
1171 .BR grpquota | noquota | quota | usrquota
1172 These options are accepted but ignored.
1175 Do not attach buffer_heads to file pagecache. (Since 2.5.49.)
1178 Disables 32-bit UIDs and GIDs. This is for interoperability with older
1179 kernels which only store and expect 16-bit values.
1181 .BR oldalloc " or " orlov
1182 Use old allocator or Orlov allocator for new inodes. Orlov is default.
1184 \fBresgid=\fP\fIn\fP and \fBresuid=\fP\fIn\fP
1185 The ext2 filesystem reserves a certain percentage of the available
1186 space (by default 5%, see
1190 These options determine who can use the reserved blocks.
1191 (Roughly: whoever has the specified uid, or belongs to the specified group.)
1194 Instead of block 1, use block
1196 as superblock. This could be useful when the filesystem has been damaged.
1197 (Earlier, copies of the superblock would be made every 8192 blocks: in
1198 block 1, 8193, 16385, ... (and one got thousands of copies on
1199 a big filesystem). Since version 1.08,
1201 has a \-s (sparse superblock) option to reduce the number of backup
1202 superblocks, and since version 1.15 this is the default. Note
1203 that this may mean that ext2 filesystems created by a recent
1205 cannot be mounted r/w under Linux 2.0.*.)
1206 The block number here uses 1k units. Thus, if you want to use logical
1207 block 32768 on a filesystem with 4k blocks, use "sb=131072".
1209 .BR user_xattr | nouser_xattr
1210 Support "user." extended attributes (or not).
1211 .\" requires CONFIG_EXT2_FS_XATTR
1214 .SH "Mount options for ext3"
1215 The ext3 filesystem is a version of the ext2 filesystem which has been
1216 enhanced with journalling. It supports the same options as ext2 as
1217 well as the following additions:
1220 .\" Mount the filesystem in abort mode, as if a fatal error has occurred.
1223 Update the ext3 filesystem's journal to the current format.
1226 When a journal already exists, this option is ignored. Otherwise, it
1227 specifies the number of the inode which will represent the ext3 filesystem's
1228 journal file; ext3 will create a new journal, overwriting the old contents
1229 of the file whose inode number is
1233 Do not load the ext3 filesystem's journal on mounting.
1235 .BR data= { journal | ordered | writeback }
1236 Specifies the journalling mode for file data. Metadata is always journaled.
1237 To use modes other than
1239 on the root filesystem, pass the mode to the kernel as boot parameter, e.g.
1240 .IR rootflags=data=journal .
1244 All data is committed into the journal prior to being written into the
1248 This is the default mode. All data is forced directly out to the main file
1249 system prior to its metadata being committed to the journal.
1252 Data ordering is not preserved - data may be written into the main
1253 filesystem after its metadata has been committed to the journal.
1254 This is rumoured to be the highest-throughput option. It guarantees
1255 internal filesystem integrity, however it can allow old data to appear
1256 in files after a crash and journal recovery.
1259 .BR barrier=0 " / " barrier=1 "
1260 This enables/disables barriers. barrier=0 disables it, barrier=1 enables it.
1261 The ext3 filesystem does not enable write barriers by default.
1264 Sync all data and metadata every
1266 seconds. The default value is 5 seconds. Zero means default.
1269 Enable Extended User Attributes. See the
1274 Enable POSIX Access Control Lists. See the
1278 .SH "Mount options for ext4"
1279 The ext4 filesystem is an an advanced level of the ext3 filesystem which
1280 incorporates scalability and reliability enhancements for supporting large
1284 .B journal_dev, noload, data, commit, orlov, oldalloc, [no]user_xattr
1285 .B [no]acl, bsddf, minixdf, debug, errors, data_err, grpid, bsdgroups, nogrpid
1286 .B sysvgroups, resgid, resuid, sb, quota, noquota, grpquota, usrquota
1289 are backwardly compatible with ext3 or ext2.
1291 .BR journal_checksum
1292 Enable checksumming of the journal transactions. This will allow the recovery
1293 code in e2fsck and the kernel to detect corruption in the kernel. It is a
1294 compatible change and will be ignored by older kernels.
1296 .BR journal_async_commit
1297 Commit block can be written to disk without waiting for descriptor blocks. If
1298 enabled older kernels cannot mount the device. This will enable
1299 'journal_checksum' internally.
1302 Update the ext4 filesystem's journal to the current format.
1304 .BR barrier=0 " / " barrier=1 " / " barrier " / " nobarrier
1305 This enables/disables the use of write barriers in the jbd code. barrier=0
1306 disables, barrier=1 enables. This also requires an IO stack which can support
1307 barriers, and if jbd gets an error on a barrier write, it will disable again
1308 with a warning. Write barriers enforce proper on-disk ordering of journal
1309 commits, making volatile disk write caches safe to use, at some performance
1310 penalty. If your disks are battery-backed in one way or another, disabling
1311 barriers may safely improve performance. The mount options "barrier" and
1312 "nobarrier" can also be used to enable or disable barriers, for consistency
1313 with other ext4 mount options.
1315 The ext4 filesystem enables write barriers by default.
1317 .BI inode_readahead= n
1318 This tuning parameter controls the maximum number of inode table blocks that
1319 ext4's inode table readahead algorithm will pre-read into the buffer cache.
1320 The default value is 32 blocks.
1323 Number of filesystem blocks that mballoc will try to use for allocation size
1324 and alignment. For RAID5/6 systems this should be the number of data disks *
1325 RAID chunk size in filesystem blocks.
1328 Deferring block allocation until write-out time.
1331 Disable delayed allocation. Blocks are allocation when data is copied from user
1334 .BI max_batch_time= usec
1335 Maximum amount of time ext4 should wait for additional filesystem operations to
1336 be batch together with a synchronous write operation. Since a synchronous
1337 write operation is going to force a commit and then a wait for the I/O
1338 complete, it doesn't cost much, and can be a huge throughput win, we wait for a
1339 small amount of time to see if any other transactions can piggyback on the
1340 synchronous write. The algorithm used is designed to automatically tune for
1341 the speed of the disk, by measuring the amount of time (on average) that it
1342 takes to finish committing a transaction. Call this time the "commit time".
1343 If the time that the transactoin has been running is less than the commit time,
1344 ext4 will try sleeping for the commit time to see if other operations will join
1345 the transaction. The commit time is capped by the max_batch_time, which
1346 defaults to 15000us (15ms). This optimization can be turned off entirely by
1347 setting max_batch_time to 0.
1349 .BI min_batch_time= usec
1350 This parameter sets the commit time (as described above) to be at least
1351 min_batch_time. It defaults to zero microseconds. Increasing this parameter
1352 may improve the throughput of multi-threaded, synchronous workloads on very
1353 fast disks, at the cost of increasing latency.
1355 .BI journal_ioprio= prio
1356 The I/O priority (from 0 to 7, where 0 is the highest priorty) which should be
1357 used for I/O operations submitted by kjournald2 during a commit operation.
1358 This defaults to 3, which is a slightly higher priority than the default I/O
1361 .BR auto_da_alloc | noauto_da_alloc
1362 Many broken applications don't use fsync() when noauto_da_alloc
1363 replacing existing files via patterns such as
1365 fd = open("foo.new")/write(fd,..)/close(fd)/ rename("foo.new", "foo")
1369 fd = open("foo", O_TRUNC)/write(fd,..)/close(fd).
1371 If auto_da_alloc is enabled, ext4 will detect the replace-via-rename and
1372 replace-via-truncate patterns and force that any delayed allocation blocks are
1373 allocated such that at the next journal commit, in the default data=ordered
1374 mode, the data blocks of the new file are forced to disk before the rename()
1375 operation is commited. This provides roughly the same level of guarantees as
1376 ext3, and avoids the "zero-length" problem that can happen when a system
1377 crashes before the delayed allocation blocks are forced to disk.
1379 .SH "Mount options for fat"
1382 is not a separate filesystem, but a common part of the
1389 .BR blocksize= { 512 | 1024 | 2048 }
1390 Set blocksize (default 512). This option is obsolete.
1392 \fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP
1393 Set the owner and group of all files.
1394 (Default: the uid and gid of the current process.)
1397 Set the umask (the bitmask of the permissions that are
1399 present). The default is the umask of the current process.
1400 The value is given in octal.
1403 Set the umask applied to directories only.
1404 The default is the umask of the current process.
1405 The value is given in octal.
1406 .\" Present since Linux 2.5.43.
1409 Set the umask applied to regular files only.
1410 The default is the umask of the current process.
1411 The value is given in octal.
1412 .\" Present since Linux 2.5.43.
1414 .BI allow_utime= value
1415 This option controls the permission check of mtime/atime.
1419 If current process is in group of file's group ID, you can change timestamp.
1422 Other users can change timestamp.
1424 The default is set from `dmask' option. (If the directory is writable,
1426 is also allowed. I.e. ~dmask & 022)
1430 checks current process is owner of the file, or it has
1431 CAP_FOWNER capability. But FAT filesystem doesn't have uid/gid on disk, so
1432 normal check is too unflexible. With this option you can relax it.
1436 Three different levels of pickyness can be chosen:
1440 Upper and lower case are accepted and equivalent, long name parts are
1442 .I verylongname.foobar
1445 leading and embedded spaces are accepted in each name part (name and extension).
1448 Like "relaxed", but many special characters (*, ?, <, spaces, etc.) are
1449 rejected. This is the default.
1452 Like "normal", but names may not contain long parts and special characters
1453 that are sometimes used on Linux, but are not accepted by MS-DOS are
1454 rejected. (+, =, spaces, etc.)
1458 Sets the codepage for converting to shortname characters on FAT
1459 and VFAT filesystems. By default, codepage 437 is used.
1461 .BR conv= {b [ inary ]| t [ ext ]| a [ uto ]}
1464 filesystem can perform CRLF<-->NL (MS-DOS text format to UNIX text
1465 format) conversion in the kernel. The following conversion modes are
1470 no translation is performed. This is the default.
1473 CRLF<-->NL translation is performed on all files.
1476 CRLF<-->NL translation is performed on all files that don't have a
1477 "well-known binary" extension. The list of known extensions can be found at
1480 (as of 2.0, the list is: exe, com, bin, app, sys, drv, ovl, ovr, obj,
1481 lib, dll, pif, arc, zip, lha, lzh, zoo, tar, z, arj, tz, taz, tzp, tpz,
1482 gz, tgz, deb, gif, bmp, tif, gl, jpg, pcx, tfm, vf, gf, pk, pxl, dvi).
1484 Programs that do computed lseeks won't like in-kernel text conversion.
1485 Several people have had their data ruined by this translation. Beware!
1487 For filesystems mounted in binary mode, a conversion tool
1488 (fromdos/todos) is available. This option is obsolete.
1491 .BI cvf_format= module
1492 Forces the driver to use the CVF (Compressed Volume File) module
1494 instead of auto-detection. If the kernel supports kmod, the
1495 cvf_format=xxx option also controls on-demand CVF module loading.
1496 This option is obsolete.
1498 .BI cvf_option= option
1499 Option passed to the CVF module. This option is obsolete.
1504 flag. A version string and a list of filesystem parameters will be
1505 printed (these data are also printed if the parameters appear to be
1508 .BR fat= {12 | 16 | 32 }
1509 Specify a 12, 16 or 32 bit fat. This overrides
1510 the automatic FAT type detection routine. Use with caution!
1512 .BI iocharset= value
1513 Character set to use for converting between 8 bit characters
1514 and 16 bit Unicode characters. The default is iso8859-1.
1515 Long filenames are stored on disk in Unicode format.
1518 This option disables the conversion of timestamps
1519 between local time (as used by Windows on FAT) and UTC
1520 (which Linux uses internally). This is particuluarly
1521 useful when mounting devices (like digital cameras)
1522 that are set to UTC in order to avoid the pitfalls of
1528 flag. Attempts to chown or chmod files do not return errors,
1529 although they fail. Use with caution!
1532 If set, the execute permission bits of the file will be allowed only if
1533 the extension part of the name is .EXE, .COM, or .BAT. Not set by default.
1536 If set, ATTR_SYS attribute on FAT is handled as IMMUTABLE flag on Linux.
1540 If set, the filesystem will try to flush to disk more early than normal.
1544 Use the "free clusters" value stored on FSINFO. It'll
1545 be used to determine number of free clusters without
1546 scanning disk. But it's not used by default, because
1547 recent Windows don't update it correctly in some
1548 case. If you are sure the "free clusters" on FSINFO is
1549 correct, by this option you can avoid scanning disk.
1551 .BR dots ", " nodots ", " dotsOK= [ yes | no ]
1552 Various misguided attempts to force Unix or DOS conventions
1553 onto a FAT filesystem.
1555 .SH "Mount options for hfs"
1557 .BI creator= cccc ", type=" cccc
1558 Set the creator/type values as shown by the MacOS finder
1559 used for creating new files. Default values: '????'.
1561 .BI uid= n ", gid=" n
1562 Set the owner and group of all files.
1563 (Default: the uid and gid of the current process.)
1565 .BI dir_umask= n ", file_umask=" n ", umask=" n
1566 Set the umask used for all directories, all regular files, or all
1567 files and directories. Defaults to the umask of the current process.
1570 Select the CDROM session to mount.
1571 Defaults to leaving that decision to the CDROM driver.
1572 This option will fail with anything but a CDROM as underlying device.
1575 Select partition number n from the device.
1576 Only makes sense for CDROMS.
1577 Defaults to not parsing the partition table at all.
1580 Don't complain about invalid mount options.
1582 .SH "Mount options for hpfs"
1584 \fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP
1585 Set the owner and group of all files. (Default: the uid and gid
1586 of the current process.)
1589 Set the umask (the bitmask of the permissions that are
1591 present). The default is the umask of the current process.
1592 The value is given in octal.
1594 .BR case= { lower | asis }
1595 Convert all files names to lower case, or leave them.
1599 .BR conv= { binary | text | auto }
1602 delete some random CRs (in particular, all followed by NL)
1603 when reading a file.
1606 choose more or less at random between
1607 .BR conv=binary " and " conv=text .
1610 just read what is in the file. This is the default.
1613 Do not abort mounting when certain consistency checks fail.
1615 .SH "Mount options for iso9660"
1616 ISO 9660 is a standard describing a filesystem structure to be used
1617 on CD-ROMs. (This filesystem type is also seen on some DVDs. See also the
1623 filenames appear in a 8.3 format (i.e., DOS-like restrictions on filename
1624 length), and in addition all characters are in upper case. Also there is
1625 no field for file ownership, protection, number of links, provision for
1626 block/character devices, etc.
1628 Rock Ridge is an extension to iso9660 that provides all of these unix like
1629 features. Basically there are extensions to each directory record that
1630 supply all of the additional information, and when Rock Ridge is in use,
1631 the filesystem is indistinguishable from a normal UNIX filesystem (except
1632 that it is read-only, of course).
1635 Disable the use of Rock Ridge extensions, even if available. Cf.\&
1639 Disable the use of Microsoft Joliet extensions, even if available. Cf.\&
1642 .BR check= { r [ elaxed ]| s [ trict ]}
1645 a filename is first converted to lower case before doing the lookup.
1646 This is probably only meaningful together with
1653 \fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP
1654 Give all files in the filesystem the indicated user or group id,
1655 possibly overriding the information found in the Rock Ridge extensions.
1659 .BR map= { n [ ormal ]| o [ ff ]| a [ corn ]}
1660 For non-Rock Ridge volumes, normal name translation maps upper
1661 to lower case ASCII, drops a trailing `;1', and converts `;' to `.'.
1664 no name translation is done. See
1671 but also apply Acorn extensions if present.
1674 For non-Rock Ridge volumes, give all files the indicated mode.
1675 (Default: read permission for everybody.)
1676 Since Linux 2.1.37 one no longer needs to specify the mode in
1677 decimal. (Octal is indicated by a leading 0.)
1680 Also show hidden and associated files.
1681 (If the ordinary files and the associated or hidden files have
1682 the same filenames, this may make the ordinary files inaccessible.)
1684 .BR block= { 512 | 1024 | 2048 }
1685 Set the block size to the indicated value.
1689 .BR conv= { a [ uto ]| b [ inary ]| m [ text ]| t [ ext ]}
1692 Since Linux 1.3.54 this option has no effect anymore.
1693 (And non-binary settings used to be very dangerous,
1694 possibly leading to silent data corruption.)
1697 If the high byte of the file length contains other garbage,
1698 set this mount option to ignore the high order bits of the file length.
1699 This implies that a file cannot be larger than 16MB.
1702 Select number of session on multisession CD. (Since 2.3.4.)
1705 Session begins from sector xxx. (Since 2.3.4.)
1707 The following options are the same as for vfat and specifying them only makes
1708 sense when using discs encoded using Microsoft's Joliet extensions.
1710 .BI iocharset= value
1711 Character set to use for converting 16 bit Unicode characters on CD
1712 to 8 bit characters. The default is iso8859-1.
1715 Convert 16 bit Unicode characters on CD to UTF-8.
1717 .SH "Mount options for jfs"
1720 Character set to use for converting from Unicode to ASCII. The default is
1721 to do no conversion. Use
1723 for UTF8 translations. This requires CONFIG_NLS_UTF8 to be set in
1729 Resize the volume to
1731 blocks. JFS only supports growing a volume, not shrinking it. This option
1732 is only valid during a remount, when the volume is mounted read-write. The
1734 keyword with no value will grow the volume to the full size of the partition.
1737 Do not write to the journal. The primary use of this option is to allow
1738 for higher performance when restoring a volume from backup media. The
1739 integrity of the volume is not guaranteed if the system abnormally abends.
1742 Default. Commit metadata changes to the journal. Use this option to remount
1745 option was previously specified in order to restore normal behavior.
1747 .BR errors= { continue | remount-ro | panic }
1748 Define the behaviour when an error is encountered.
1749 (Either ignore errors and just mark the filesystem erroneous and continue,
1750 or remount the filesystem read-only, or panic and halt the system.)
1752 .BR noquota | quota | usrquota | grpquota
1753 These options are accepted but ignored.
1755 .SH "Mount options for minix"
1758 .SH "Mount options for msdos"
1759 See mount options for fat.
1762 filesystem detects an inconsistency, it reports an error and sets the file
1763 system read-only. The filesystem can be made writeable again by remounting
1766 .SH "Mount options for ncpfs"
1768 .IR nfs ", the " ncpfs
1769 implementation expects a binary argument (a
1770 .IR "struct ncp_mount_data" )
1771 to the mount system call. This argument is constructed by
1773 and the current version of
1775 (2.12) does not know anything about ncpfs.
1777 .SH "Mount options for nfs and nfs4"
1778 See the options section of the
1780 man page (nfs-utils package must be installed).
1783 .IR nfs " and " nfs4
1784 implementation expects a binary argument (a
1785 .IR "struct nfs_mount_data" )
1786 to the mount system call. This argument is constructed by
1788 and the current version of
1790 (2.13) does not know anything about nfs and nfs4.
1792 .SH "Mount options for ntfs"
1795 Character set to use when returning file names.
1796 Unlike VFAT, NTFS suppresses names that contain
1797 unconvertible characters. Deprecated.
1801 New name for the option earlier called
1806 Use UTF-8 for converting file names.
1808 .BR uni_xlate= { 0 | 1 | 2 }
1809 For 0 (or `no' or `false'), do not use escape sequences
1810 for unknown Unicode characters.
1811 For 1 (or `yes' or `true') or 2, use vfat-style 4-byte escape sequences
1812 starting with ":". Here 2 give a little-endian encoding
1813 and 1 a byteswapped bigendian encoding.
1816 If enabled (posix=1), the filesystem distinguishes between
1817 upper and lower case. The 8.3 alias names are presented as
1818 hard links instead of being suppressed. This option is obsolete.
1820 \fBuid=\fP\fIvalue\fP, \fBgid=\fP\fIvalue\fP and \fBumask=\fP\fIvalue\fP
1821 Set the file permission on the filesystem.
1822 The umask value is given in octal.
1823 By default, the files are owned by root and not readable by somebody else.
1825 .SH "Mount options for proc"
1827 \fBuid=\fP\fIvalue\fP and \fBgid=\fP\fIvalue\fP
1828 These options are recognized, but have no effect as far as I can see.
1830 .SH "Mount options for ramfs"
1831 Ramfs is a memory based filesystem. Mount it and you have it. Unmount it
1832 and it is gone. Present since Linux 2.3.99pre4.
1833 There are no mount options.
1835 .SH "Mount options for reiserfs"
1836 Reiserfs is a journaling filesystem.
1839 Instructs version 3.6 reiserfs software to mount a version 3.5 filesystem,
1840 using the 3.6 format for newly created objects. This filesystem will no
1841 longer be compatible with reiserfs 3.5 tools.
1843 .BR hash= { rupasov | tea | r5 | detect }
1844 Choose which hash function reiserfs will use to find files within directories.
1848 A hash invented by Yury Yu. Rupasov. It is fast and preserves locality,
1849 mapping lexicographically close file names to close hash values.
1850 This option should not be used, as it causes a high probability of hash
1854 A Davis-Meyer function implemented by Jeremy Fitzhardinge.
1855 It uses hash permuting bits in the name. It gets high randomness
1856 and, therefore, low probability of hash collisions at some CPU cost.
1857 This may be used if EHASHCOLLISION errors are experienced with the r5 hash.
1860 A modified version of the rupasov hash. It is used by default and is
1861 the best choice unless the filesystem has huge directories and
1862 unusual file-name patterns.
1867 to detect which hash function is in use by examining
1868 the filesystem being mounted, and to write this information into
1869 the reiserfs superblock. This is only useful on the first mount of
1870 an old format filesystem.
1873 .BR hashed_relocation
1874 Tunes the block allocator. This may provide performance improvements
1877 .BR no_unhashed_relocation
1878 Tunes the block allocator. This may provide performance improvements
1882 Disable the border allocator algorithm invented by Yury Yu. Rupasov.
1883 This may provide performance improvements in some situations.
1886 Disable journalling. This will provide slight performance improvements in
1887 some situations at the cost of losing reiserfs's fast recovery from crashes.
1888 Even with this option turned on, reiserfs still performs all journalling
1889 operations, save for actual writes into its journalling area. Implementation
1892 is a work in progress.
1895 By default, reiserfs stores small files and `file tails' directly into its
1896 tree. This confuses some utilities such as
1898 This option is used to disable packing of files into the tree.
1901 Replay the transactions which are in the journal, but do not actually
1902 mount the filesystem. Mainly used by
1906 A remount option which permits online expansion of reiserfs partitions.
1907 Instructs reiserfs to assume that the device has
1910 This option is designed for use with devices which are under logical
1911 volume management (LVM).
1914 utility which can be obtained from
1915 .IR ftp://ftp.namesys.com/pub/reiserfsprogs .
1918 Enable Extended User Attributes. See the
1923 Enable POSIX Access Control Lists. See the
1927 .SH "Mount options for romfs"
1930 .SH "Mount options for smbfs"
1932 .IR nfs ", the " smbfs
1933 implementation expects a binary argument (a
1934 .IR "struct smb_mount_data" )
1935 to the mount system call. This argument is constructed by
1937 and the current version of
1939 (2.12) does not know anything about smbfs.
1941 .SH "Mount options for sysv"
1944 .SH "Mount options for tmpfs"
1947 Override default maximum size of the filesystem.
1948 The size is given in bytes, and rounded up to entire pages.
1949 The default is half of the memory. The size parameter also accepts a suffix %
1950 to limit this tmpfs instance to that percentage of your physical RAM:
1951 the default, when neither size nor nr_blocks is specified, is size=50%
1954 The same as size, but in blocks of PAGE_CACHE_SIZE
1957 The maximum number of inodes for this instance. The default
1958 is half of the number of your physical RAM pages, or (on a
1959 machine with highmem) the number of lowmem RAM pages,
1960 whichever is the lower.
1962 The tmpfs mount options for sizing (
1972 for Ki, Mi, Gi (binary kilo, mega and giga) and can be changed on remount.
1976 Set initial permissions of the root directory.
1984 .B mpol=[default|prefer:Node|bind:NodeList|interleave|interleave:NodeList]
1985 Set the NUMA memory allocation policy for all files in that
1986 instance (if the kernel CONFIG_NUMA is enabled) - which can be adjusted on the
1987 fly via 'mount -o remount ...'
1991 prefers to allocate memory from the local node
1994 prefers to allocate memory from the given Node
1997 allocates memory only from nodes in NodeList
2000 prefers to allocate from each node in turn
2002 .B interleave:NodeList
2003 allocates from each node of NodeList in turn.
2005 The NodeList format is a comma-separated list of decimal numbers and ranges, a
2006 range being two hyphen-separated decimal numbers, the smallest and largest node
2007 numbers in the range. For example, mpol=bind:0-3,5,7,9-15
2009 Note that trying to mount a tmpfs with an mpol option will fail if the
2010 running kernel does not support NUMA; and will fail if its nodelist
2011 specifies a node which is not online. If your system relies on that
2012 tmpfs being mounted, but from time to time runs a kernel built without
2013 NUMA capability (perhaps a safe recovery kernel), or with fewer nodes
2014 online, then it is advisable to omit the mpol option from automatic
2015 mount options. It can be added later, when the tmpfs is already mounted
2016 on MountPoint, by 'mount -o remount,mpol=Policy:NodeList MountPoint'.
2019 .SH "Mount options for udf"
2020 udf is the "Universal Disk Format" filesystem defined by the Optical
2021 Storage Technology Association, and is often used for DVD-ROM.
2026 Set the default group.
2029 Set the default umask.
2030 The value is given in octal.
2033 Set the default user.
2036 Show otherwise hidden files.
2039 Show deleted files in lists.
2042 Unset strict conformance.
2048 Set the NLS character set.
2051 Set the block size. (May not work unless 2048.)
2054 Skip volume sequence recognition.
2057 Set the CDROM session counting from 0. Default: last session.
2060 Override standard anchor location. Default: 256.
2063 Override the VolumeDesc location. (unused)
2066 Override the PartitionDesc location. (unused)
2069 Set the last block of the filesystem.
2072 Override the fileset block location. (unused)
2075 Override the root directory location. (unused)
2077 .SH "Mount options for ufs"
2080 UFS is a filesystem widely used in different operating systems.
2081 The problem are differences among implementations. Features of some
2082 implementations are undocumented, so its hard to recognize the
2083 type of ufs automatically.
2084 That's why the user must specify the type of ufs by mount option.
2085 Possible values are:
2089 Old format of ufs, this is the default, read only.
2090 (Don't forget to give the \-r option.)
2093 For filesystems created by a BSD-like system (NetBSD,FreeBSD,OpenBSD).
2096 For filesystems created by SunOS or Solaris on Sparc.
2099 For filesystems created by Solaris on x86.
2102 For filesystems created by HP-UX, read-only.
2105 For filesystems created by NeXTStep (on NeXT station) (currently read only).
2108 For NextStep CDROMs (block_size == 2048), read-only.
2111 For filesystems created by OpenStep (currently read only).
2112 The same filesystem type is also used by Mac OS X.
2117 Set behaviour on error:
2121 If an error is encountered, cause a kernel panic.
2123 .RB [ lock | umount | repair ]
2124 These mount options don't do anything at present;
2125 when an error is encountered only a console message is printed.
2128 .SH "Mount options for umsdos"
2129 See mount options for msdos.
2132 option is explicitly killed by
2135 .SH "Mount options for vfat"
2136 First of all, the mount options for
2141 option is explicitly killed by
2143 Furthermore, there are
2146 Translate unhandled Unicode characters to special escaped sequences.
2147 This lets you backup and restore filenames that are created with any
2148 Unicode characters. Without this option, a '?' is used when no
2149 translation is possible. The escape character is ':' because it is
2150 otherwise illegal on the vfat filesystem. The escape sequence
2151 that gets used, where u is the unicode character,
2152 is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).
2155 Allow two files with names that only differ in case.
2158 First try to make a short name without sequence number,
2163 UTF8 is the filesystem safe 8-bit encoding of Unicode that is used by the
2164 console. It can be be enabled for the filesystem with this option or disabled
2165 with utf8=0, utf8=no or utf8=false. If `uni_xlate' gets set, UTF8 gets
2168 .BR shortname= { lower | win95 | winnt | mixed }
2170 Defines the behaviour for creation and display of filenames which fit into
2171 8.3 characters. If a long name for a file exists, it will always be
2172 preferred display. There are four modes:
2177 Force the short name to lower case upon display; store a long name when
2178 the short name is not all upper case. This mode is the default.
2181 Force the short name to upper case upon display; store a long name when
2182 the short name is not all upper case.
2185 Display the shortname as is; store a long name when the short name is
2186 not all lower case or all upper case.
2189 Display the short name as is; store a long name when the short name is not
2194 .SH "Mount options for usbfs"
2196 \fBdevuid=\fP\fIuid\fP and \fBdevgid=\fP\fIgid\fP and \fBdevmode=\fP\fImode\fP
2197 Set the owner and group and mode of the device files in the usbfs filesystem
2198 (default: uid=gid=0, mode=0644). The mode is given in octal.
2200 \fBbusuid=\fP\fIuid\fP and \fBbusgid=\fP\fIgid\fP and \fBbusmode=\fP\fImode\fP
2201 Set the owner and group and mode of the bus directories in the usbfs
2202 filesystem (default: uid=gid=0, mode=0555). The mode is given in octal.
2204 \fBlistuid=\fP\fIuid\fP and \fBlistgid=\fP\fIgid\fP and \fBlistmode=\fP\fImode\fP
2205 Set the owner and group and mode of the file
2207 (default: uid=gid=0, mode=0444). The mode is given in octal.
2209 .SH "Mount options for xenix"
2212 .SH "Mount options for xfs"
2215 Sets the buffered I/O end-of-file preallocation size when
2216 doing delayed allocation writeout (default size is 64KiB).
2217 Valid values for this option are page size (typically 4KiB)
2218 through to 1GiB, inclusive, in power-of-2 increments.
2221 The options enable/disable (default is disabled for backward
2222 compatibility on-disk) an "opportunistic" improvement to be
2223 made in the way inline extended attributes are stored on-disk.
2224 When the new form is used for the first time (by setting or
2225 removing extended attributes) the on-disk superblock feature
2226 bit field will be updated to reflect this format being in use.
2229 Enables the use of block layer write barriers for writes into
2230 the journal and unwritten extent conversion. This allows for
2231 drive level write caching to be enabled, for devices that
2232 support write barriers.
2235 Enable the DMAPI (Data Management API) event callouts.
2240 .BR grpid | bsdgroups " and " nogrpid | sysvgroups
2241 These options define what group ID a newly created file gets.
2242 When grpid is set, it takes the group ID of the directory in
2243 which it is created; otherwise (the default) it takes the fsgid
2244 of the current process, unless the directory has the setgid bit
2245 set, in which case it takes the gid from the parent directory,
2246 and also gets the setgid bit set if it is a directory itself.
2248 .BI ihashsize= value
2249 Sets the number of hash buckets available for hashing the
2250 in-memory inodes of the specified mount point. If a value
2251 of zero is used, the value selected by the default algorithm
2252 will be displayed in
2256 When inode clusters are emptied of inodes, keep them around
2257 on the disk (ikeep) - this is the traditional XFS behaviour
2258 and is still the default for now. Using the noikeep option,
2259 inode clusters are returned to the free space pool.
2262 Indicates that XFS is allowed to create inodes at any location
2263 in the filesystem, including those which will result in inode
2264 numbers occupying more than 32 bits of significance. This is
2265 provided for backwards compatibility, but causes problems for
2266 backup applications that cannot handle large inode numbers.
2268 .BR largeio | nolargeio
2271 is specified, the optimal I/O reported in
2274 will be as small as possible to allow user
2275 applications to avoid inefficient read/modify/write I/O.
2278 is specified, a filesystem that has a
2283 value (in bytes) in st_blksize. If the
2284 filesystem does not have a
2286 specified but does specify
2291 (in bytes) will be returned
2293 If neither of these two options are specified, then filesystem
2299 Set the number of in-memory log buffers. Valid numbers range
2301 The default value is 8 buffers for filesystems with a
2302 blocksize of 64KiB, 4 buffers for filesystems with a blocksize
2303 of 32KiB, 3 buffers for filesystems with a blocksize of 16KiB
2304 and 2 buffers for all other configurations. Increasing the
2305 number of buffers may increase performance on some workloads
2306 at the cost of the memory used for the additional log buffers
2307 and their associated control structures.
2310 Set the size of each in-memory log buffer.
2311 Size may be specified in bytes, or in kilobytes with a "k" suffix.
2312 Valid sizes for version 1 and version 2 logs are 16384 (16k) and
2313 32768 (32k). Valid sizes for version 2 logs also include
2314 65536 (64k), 131072 (128k) and 262144 (256k).
2315 The default value for machines with more than 32MiB of memory
2316 is 32768, machines with less memory use 16384 by default.
2318 \fBlogdev=\fP\fIdevice\fP and \fBrtdev=\fP\fIdevice\fP
2319 Use an external log (metadata journal) and/or real-time device.
2320 An XFS filesystem has up to three parts: a data section, a log section,
2321 and a real-time section.
2322 The real-time section is optional, and the log section can be separate
2323 from the data section or contained within it.
2327 .BI mtpt= mountpoint
2330 option. The value specified here will be
2331 included in the DMAPI mount event, and should be the path of
2332 the actual mountpoint that is used.
2335 Data allocations will not be aligned at stripe unit boundaries.
2338 Access timestamps are not updated when a file is read.
2341 The filesystem will be mounted without running log recovery.
2342 If the filesystem was not cleanly unmounted, it is likely to
2343 be inconsistent when mounted in
2346 Some files or directories may not be accessible because of this.
2349 must be mounted read-only or the mount will fail.
2352 Don't check for double mounted filesystems using the filesystem uuid.
2353 This is useful to mount LVM snapshot volumes.
2356 Make O_SYNC writes implement true O_SYNC. WITHOUT this option,
2357 Linux XFS behaves as if an
2360 which will make writes to files opened with the O_SYNC flag set
2361 behave as if the O_DSYNC flag had been used instead.
2362 This can result in better performance without compromising
2364 However if this option is not in effect, timestamp updates from
2365 O_SYNC writes can be lost if the system crashes.
2366 If timestamp updates are critical, use the
2370 .BR uquota | usrquota | uqnoenforce | quota
2371 User disk quota accounting enabled, and limits (optionally)
2374 for further details.
2376 .BR gquota | grpquota | gqnoenforce
2377 Group disk quota accounting enabled and limits (optionally)
2380 for further details.
2382 .BR pquota | prjquota | pqnoenforce
2383 Project disk quota accounting enabled and limits (optionally)
2386 for further details.
2388 \fBsunit=\fP\fIvalue\fP and \fBswidth=\fP\fIvalue\fP
2389 Used to specify the stripe unit and width for a RAID device or a stripe
2392 must be specified in 512-byte block units.
2393 If this option is not specified and the filesystem was made on a stripe
2394 volume or the stripe width or unit were specified for the RAID device at
2395 mkfs time, then the mount system call will restore the value from the
2397 For filesystems that are made directly on RAID devices, these options can be
2398 used to override the information in the superblock if the underlying disk
2399 layout changes after the filesystem has been created.
2402 option is required if the
2404 option has been specified,
2405 and must be a multiple of the
2410 Data allocations will be rounded up to stripe width boundaries
2411 when the current end of file is being extended and the file
2412 size is larger than the stripe width size.
2414 .SH "Mount options for xiafs"
2415 None. Although nothing is wrong with xiafs, it is not used much,
2416 and is not maintained. Probably one shouldn't use it.
2417 Since Linux version 2.1.21 xiafs is no longer part of the kernel source.
2419 .SH "THE LOOP DEVICE"
2420 One further possible type is a mount via the loop device. For example,
2424 .B " mount /tmp/fdimage /mnt -t vfat -o loop=/dev/loop3
2427 will set up the loop device
2429 to correspond to the file
2431 and then mount this device on
2434 This type of mount knows about four options, namely
2435 .BR loop ", " offset ", " sizelimit " and " encryption ,
2436 that are really options to
2438 (These options can be used in addition to those specific
2439 to the filesystem type.)
2441 If no explicit loop device is mentioned
2442 (but just an option `\fB\-o loop\fP' is given), then
2444 will try to find some unused loop device and use that.
2446 Since Linux 2.6.25 is supported auto-destruction of loop devices and
2447 then any loop device allocated by
2454 You can also free a loop device by hand, using `losetup -d' or `umount -d`.
2458 has the following return codes (the bits can be ORed):
2464 incorrect invocation or permissions
2467 system error (out of memory, cannot fork, no more loop devices)
2478 problems writing or locking /etc/mtab
2484 some mount succeeded
2487 The syntax of external mount helpers is:
2490 .BI /sbin/mount. <suffix>
2497 where the <suffix> is filesystem type and \-sfnvo options have same meaning like
2498 standard mount options.
2506 table of mounted filesystems
2515 a list of filesystem types to try
2533 It is possible for a corrupted filesystem to cause a crash.
2535 Some Linux filesystems don't support
2536 .B "\-o sync and \-o dirsync"
2537 (the ext2, ext3, fat and vfat filesystems
2539 support synchronous updates (a la BSD) when mounted with the
2545 may not be able to change mount parameters (all
2546 .IR ext2fs -specific
2549 are changeable with a remount, for example, but you can't change
2556 Mount by label or uuid will work only if your devices have the names listed in
2557 .IR /proc/partitions .
2558 In particular, it may well fail if the kernel was compiled with devfs
2559 but devfs is not mounted.
2561 It is possible that files
2565 don't match. The first file is based only on the mount command options, but the
2566 content of the second file also depends on the kernel and others settings (e.g.
2567 remote NFS server. In particular case the mount command may reports unreliable
2568 information about a NFS mount point and the /proc/mounts file usually contains
2569 more reliable information.)
2571 Checking files on NFS filesystem referenced by file descriptors (i.e. the
2575 families of functions) may lead to inconsistent result due to the lack of
2576 consistency check in kernel even if noac is used.
2580 command existed in Version 5 AT&T UNIX.
2582 The mount command is part of the util-linux-ng package and is available from
2583 ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
projects / framework / base / util-linux-ng.git / blob