1MOUNT(8) Linux Programmer's Manual MOUNT(8)
2
6 mount - mount a file system
7
9 mount [-lhV]
10 mount -a [-fFnrsvw] [-t vfstype] [-O optlist]
12 mount [-fnrsvw] [-o options [,...]] device | dir
13 mount [-fnrsvw] [-t vfstype] [-o options] device dir
14
16 All files accessible in a Unix system are arranged in one big tree, the
17 file hierarchy, rooted at /. These files can be spread out over sev‐
18 eral devices. The mount command serves to attach the file system found
19 on some device to the big file tree. Conversely, the umount(8) command
20 will detach it again.
21 The standard form of the mount command, is
23 mount -t type device dir
24 This tells the kernel to attach the file system found on device (which
25 is of type type) at the directory dir. The previous contents (if any)
26 and owner and mode of dir become invisible, and as long as this file
27 system remains mounted, the pathname dir refers to the root of the file
28 system on device.
29 Three forms of invocation do not actually mount anything:
31 mount -h
32 prints a help message;
33 mount -V
34 prints a version string; and just
35 mount [-l] [-t type]
36 lists all mounted file systems (of type type). The option -l adds the
37 (ext2, ext3 and XFS) labels in this listing. See below.
38 Since Linux 2.4.0 it is possible to remount part of the file hierarchy
40 somewhere else. The call is
41 mount --bind olddir newdir
42 After this call the same contents is accessible in two places. One can
43 also remount a single file (on a single file).
44 This call attaches only (part of) a single filesystem, not possible
46 submounts. The entire file hierarchy including submounts is attached a
47 second place using
48 mount --rbind olddir newdir
49 Note that the filesystem mount options will remain the same as those on
51 the original mount point, and cannot be changed by passing the -o
52 option along with --bind/--rbind.
53 Since Linux 2.5.1 it is possible to atomically move a mounted tree to
55 another place. The call is
56 mount --move olddir newdir
57 Since Linux 2.6.15 it is possible to mark a mount and its submounts as
59 shared, private, slave or unbindable. A shared mount provides ability
60 to create mirrors of that mount such that mounts and umounts within any
61 of the mirrors propagate to the other mirror. A slave mount receives
62 propagation from its master, but any not vice-versa. A private mount
63 carries no propagation abilities. A unbindable mount is a private
64 mount which cannot cloned through a bind operation. Detailed semantics
65 is documented in Documentation/sharedsubtree.txt file in the kernel
66 source tree.
67 mount --make-shared mountpoint
68 mount --make-slave mountpoint
69 mount --make-private mountpoint
70 mount --make-unbindable mountpoint
71 The following commands allows one to recursively change the type of all
73 the mounts under a given mountpoint.
74 mount --make-rshared mountpoint
75 mount --make-rslave mountpoint
76 mount --make-rprivate mountpoint
77 "mount --make-runbindable mountpoint"
78 The proc file system is not associated with a special device, and when
80 mounting it, an arbitrary keyword, such as proc can be used instead of
81 a device specification. (The customary choice none is less fortunate:
82 the error message `none busy' from umount can be confusing.)
83 Most devices are indicated by a file name (of a block special device),
85 like /dev/sda1, but there are other possibilities. For example, in the
86 case of an NFS mount, device may look like knuth.cwi.nl:/dir. It is
87 possible to indicate a block special device using its volume label or
88 UUID (see the -L and -U options below).
89 The file /etc/fstab (see fstab(5)), may contain lines describing what
91 devices are usually mounted where, using which options. This file is
92 used in three ways:
93 (i) The command
95 mount -a [-t type] [-O optlist]
96 (usually given in a bootscript) causes all file systems mentioned in
97 fstab (of the proper type and/or having or not having the proper
98 options) to be mounted as indicated, except for those whose line con‐
99 tains the noauto keyword. Adding the -F option will make mount fork, so
100 that the filesystems are mounted simultaneously.
101 (ii) When mounting a file system mentioned in fstab, it suffices to
103 give only the device, or only the mount point.
104 (iii) Normally, only the superuser can mount file systems. However,
106 when fstab contains the user option on a line, anybody can mount the
107 corresponding system.
108 Thus, given a line
110 /dev/cdrom /cd iso9660 ro,user,noauto,unhide
111 any user can mount the iso9660 file system found on his CDROM using the
112 command
113 mount /dev/cdrom
114 or
115 mount /cd
116 For more details, see fstab(5). Only the user that mounted a filesys‐
117 tem can unmount it again. If any user should be able to unmount, then
118 use users instead of user in the fstab line. The owner option is simi‐
119 lar to the user option, with the restriction that the user must be the
120 owner of the special file. This may be useful e.g. for /dev/fd if a
121 login script makes the console user owner of this device. The group
122 option is similar, with the restriction that the user must be member of
123 the group of the special file.
124 The programs mount and umount maintain a list of currently mounted file
126 systems in the file /etc/mtab. If no arguments are given to mount,
127 this list is printed.
128 When the proc filesystem is mounted (say at /proc), the files /etc/mtab
130 and /proc/mounts have very similar contents. The former has somewhat
131 more information, such as the mount options used, but is not necessar‐
132 ily up-to-date (cf. the -n option below). It is possible to replace
133 /etc/mtab by a symbolic link to /proc/mounts, and especially when you
134 have very large numbers of mounts things will be much faster with that
135 symlink, but some information is lost that way, and in particular work‐
136 ing with the loop device will be less convenient, and using the "user"
137 option will fail.
138
141 The full set of options used by an invocation of mount is determined by
142 first extracting the options for the file system from the fstab table,
143 then applying any options specified by the -o argument, and finally
144 applying a -r or -w option, when present.
145 Options available for the mount command:
147 -V Output version.
149 -h Print a help message.
151 -v Verbose mode.
153 -a Mount all filesystems (of the given types) mentioned in fstab.
155 -F (Used in conjunction with -a.) Fork off a new incarnation of
157 mount for each device. This will do the mounts on different
158 devices or different NFS servers in parallel. This has the
159 advantage that it is faster; also NFS timeouts go in parallel. A
160 disadvantage is that the mounts are done in undefined order.
161 Thus, you cannot use this option if you want to mount both /usr
162 and /usr/spool.
163 -f Causes everything to be done except for the actual system call;
165 if it's not obvious, this ``fakes'' mounting the file system.
166 This option is useful in conjunction with the -v flag to deter‐
167 mine what the mount command is trying to do. It can also be used
168 to add entries for devices that were mounted earlier with the -n
169 option.
170 -i Don't call the /sbin/mount.<filesystem> helper even if it
172 exists.
173 -l Add the ext2, ext3 and XFS labels in the mount output. Mount
175 must have permission to read the disk device (e.g. be suid root)
176 for this to work. One can set such a label for ext2 or ext3
177 using the e2label(8) utility, or for XFS using xfs_admin(8), or
178 for reiserfs using reiserfstune(8).
179 -n Mount without writing in /etc/mtab. This is necessary for exam‐
181 ple when /etc is on a read-only file system.
182 -p num In case of a loop mount with encryption, read the passphrase
184 from file descriptor num instead of from the terminal.
185 -s Tolerate sloppy mount options rather than failing. This will
187 ignore mount options not supported by a filesystem type. Not all
188 filesystems support this option. This option exists for support
189 of the Linux autofs-based automounter.
190 -r Mount the file system read-only. A synonym is -o ro.
192 -w Mount the file system read/write. This is the default. A synonym
194 is -o rw.
195 -L label
197 Mount the partition that has the specified label.
198 -U uuid
200 Mount the partition that has the specified uuid. These two
201 options require the file /proc/partitions (present since Linux
202 2.1.116) to exist.
203 -t vfstype
205 The argument following the -t is used to indicate the file sys‐
206 tem type. The file system types which are currently supported
207 include: adfs, affs, autofs, cifs, coda, coherent, cramfs,
208 debugfs, devpts, efs, ext, ext2, ext3, hfs, hpfs, iso9660, jfs,
209 minix, msdos, ncpfs, nfs, nfs4, ntfs, proc, qnx4, ramfs, reis‐
210 erfs, romfs, smbfs, sysv, tmpfs, udf, ufs, umsdos, usbfs, vfat,
211 xenix, xfs, xiafs. Note that coherent, sysv and xenix are
212 equivalent and that xenix and coherent will be removed at some
213 point in the future — use sysv instead. Since kernel version
214 2.1.21 the types ext and xiafs do not exist anymore. Earlier,
215 usbfs was known as usbdevfs.
216 For most types all the mount program has to do is issue a simple
218 mount(2) system call, and no detailed knowledge of the filesys‐
219 tem type is required. For a few types however (like nfs, nfs4,
220 cifs, smbfs, ncpfs) ad hoc code is necessary. The nfs ad hoc
221 code is built in, but cifs, smbfs, and ncpfs have a separate
222 mount program. In order to make it possible to treat all types
223 in a uniform way, mount will execute the program
224 /sbin/mount.TYPE (if that exists) when called with type TYPE.
225 Since various versions of the smbmount program have different
226 calling conventions, /sbin/mount.smbfs may have to be a shell
227 script that sets up the desired call.
228 If no -t option is given, or if the auto type is specified,
230 mount will try to guess the desired type. If mount was compiled
231 with the blkid library, the guessing is done by this library.
232 Otherwise, mount guesses itself by probing the superblock; if
233 that does not turn up anything that looks familiar, mount will
234 try to read the file /etc/filesystems, or, if that does not
235 exist, /proc/filesystems. All of the filesystem types listed
236 there will be tried, except for those that are labeled "nodev"
237 (e.g., devpts, proc, nfs, and nfs4). If /etc/filesystems ends
238 in a line with a single * only, mount will read /proc/filesys‐
239 tems afterwards.
240 The auto type may be useful for user-mounted floppies. Creating
242 a file /etc/filesystems can be useful to change the probe order
243 (e.g., to try vfat before msdos or ext3 before ext2) or if you
244 use a kernel module autoloader. Warning: the probing uses a
245 heuristic (the presence of appropriate `magic'), and could rec‐
246 ognize the wrong filesystem type, possibly with catastrophic
247 consequences. If your data is valuable, don't ask mount to
248 guess.
249 More than one type may be specified in a comma separated list.
251 The list of file system types can be prefixed with no to specify
252 the file system types on which no action should be taken. (This
253 can be meaningful with the -a option.)
254 For example, the command:
256 mount -a -t nomsdos,ext
257 mounts all file systems except those of type msdos and ext.
258 -O Used in conjunction with -a, to limit the set of filesystems to
260 which the -a is applied. Like -t in this regard except that it
261 is useless except in the context of -a. For example, the com‐
262 mand:
263 mount -a -O no_netdev
264 mounts all file systems except those which have the option _net‐
265 dev specified in the options field in the /etc/fstab file.
266 It is different from -t in that each option is matched exactly;
268 a leading no at the beginning of one option does not negate the
269 rest.
270 The -t and -O options are cumulative in effect; that is, the
272 command
273 mount -a -t ext2 -O _netdev
274 mounts all ext2 filesystems with the _netdev option, not all
275 filesystems that are either ext2 or have the _netdev option
276 specified.
277 -o Options are specified with a -o flag followed by a comma sepa‐
279 rated string of options. Some of these options are only useful
280 when they appear in the /etc/fstab file. The following options
281 apply to any file system that is being mounted (but not every
282 file system actually honors them - e.g., the sync option today
283 has effect only for ext2, ext3, fat, vfat and ufs):
284 async All I/O to the file system should be done asynchronously.
286 atime Update inode access time for each access. This is the
288 default.
289 auto Can be mounted with the -a option.
291 defaults
293 Use default options: rw, suid, dev, exec, auto, nouser,
294 and async.
295 dev Interpret character or block special devices on the file
297 system.
298 exec Permit execution of binaries.
300 group Allow an ordinary (i.e., non-root) user to mount the file
302 system if one of his groups matches the group of the
303 device. This option implies the options nosuid and nodev
304 (unless overridden by subsequent options, as in the
305 option line group,dev,suid).
306 mand Allow mandatory locks on this filesystem. See fcntl(2).
308 _netdev
310 The filesystem resides on a device that requires network
311 access (used to prevent the system from attempting to
312 mount these filesystems until the network has been
313 enabled on the system).
314 noatime
316 Do not update inode access times on this file system
317 (e.g, for faster access on the news spool to speed up
318 news servers).
319 nodiratime
321 Do not update directory inode access times on this
322 filesystem.
323 relatime
325 Update inode access times relative to modify or change
326 time. Access time is only updated if the previous access
327 time was earlier than the current modify or change time.
328 (Similar to noatime, but doesn't break mutt or other
329 applications that need to know if a file has been read
330 since the last time it was modified.)
331 noauto Can only be mounted explicitly (i.e., the -a option will
333 not cause the file system to be mounted).
334 nodev Do not interpret character or block special devices on
336 the file system.
337 noexec Do not allow direct execution of any binaries on the
339 mounted file system. (Until recently it was possible to
340 run binaries anyway using a command like /lib/ld*.so
341 /mnt/binary. This trick fails since Linux 2.4.25 /
342 2.6.0.)
343 nomand Do not allow mandatory locks on this filesystem.
345 nosuid Do not allow set-user-identifier or set-group-identifier
347 bits to take effect. (This seems safe, but is in fact
348 rather unsafe if you have suidperl(1) installed.)
349 nouser Forbid an ordinary (i.e., non-root) user to mount the
351 file system. This is the default.
352 owner Allow an ordinary (i.e., non-root) user to mount the file
354 system if he is the owner of the device. This option
355 implies the options nosuid and nodev (unless overridden
356 by subsequent options, as in the option line
357 owner,dev,suid).
358 remount
360 Attempt to remount an already-mounted file system. This
361 is commonly used to change the mount flags for a file
362 system, especially to make a readonly file system write‐
363 able. It does not change device or mount point.
364 ro Mount the file system read-only.
366 rw Mount the file system read-write.
368 suid Allow set-user-identifier or set-group-identifier bits to
370 take effect.
371 sync All I/O to the file system should be done synchronously.
373 In case of media with limited number of write cycles
374 (e.g. some flash drives) "sync" may cause life-cycle
375 shortening.
376 dirsync
378 All directory updates within the file system should be
379 done synchronously. This affects the following system
380 calls: creat, link, unlink, symlink, mkdir, rmdir, mknod
381 and rename.
382 user Allow an ordinary user to mount the file system. The
384 name of the mounting user is written to mtab so that he
385 can unmount the file system again. This option implies
386 the options noexec, nosuid, and nodev (unless overridden
387 by subsequent options, as in the option line
388 user,exec,dev,suid).
389 users Allow every user to mount and unmount the file system.
391 This option implies the options noexec, nosuid, and nodev
392 (unless overridden by subsequent options, as in the
393 option line users,exec,dev,suid).
394 context=context, fscontext=context and defcontext=context
396 The context= option is useful when mounting filesystems
397 that do not support extended attributes, such as a floppy
398 or hard disk formatted with VFAT, or systems that are not
399 normally running under SELinux, such as an ext3 formatted
400 disk from a non-SELinux workstation. You can also use
401 context= on filesystems you do not trust, such as a
402 floppy. It also helps in compatibility with xattr-sup‐
403 porting filesystems on earlier 2.4.<x> kernel versions.
404 Even where xattrs are supported, you can save time not
405 having to label every file by assigning the entire disk
406 one security context.
407 A commonly used option for removable media is con‐
409 text=system_u:object_r:removable_t.
410 Two other options are fscontext= and defcontext=, both of
412 which are mutually exclusive of the context option. This
413 means you can use fscontext and defcontext with each
414 other, but neither can be used with context.
415 The fscontext= option works for all filesystems, regard‐
417 less of their xattr support. The fscontext option sets
418 the overarching filesystem label to a specific security
419 context. This filesystem label is separate from the indi‐
420 vidual labels on the files. It represents the entire
421 filesystem for certain kinds of permission checks, such
422 as during mount or file creation. Individual file labels
423 are still obtained from the xattrs on the files them‐
424 selves. The context option actually sets the aggregate
425 context that fscontext provides, in addition to supplying
426 the same label for individual files.
427 You can set the default security context for unlabeled
429 files using defcontext= option. This overrides the value
430 set for unlabeled files in the policy and requires a file
431 system that supports xattr labeling.
432 For more details see selinux(8)
434 --bind Remount a subtree somewhere else (so that its contents are
436 available in both places). See above.
437 --move Move a subtree to some other place. See above.
439
442 The following options apply only to certain file systems. We sort them
443 by file system. They all follow the -o flag.
444 What options are supported depends a bit on the running kernel. More
446 info may be found in the kernel source subdirectory Documenta‐
447 tion/filesystems.
448
451 uid=value and gid=value
452 Set the owner and group of the files in the file system
453 (default: uid=gid=0).
454 ownmask=value and othmask=value
456 Set the permission mask for ADFS 'owner' permissions and 'other'
457 permissions, respectively (default: 0700 and 0077, respec‐
458 tively). See also /usr/src/linux/Documentation/filesys‐
459 tems/adfs.txt.
460
462 uid=value and gid=value
463 Set the owner and group of the root of the file system (default:
464 uid=gid=0, but with option uid or gid without specified value,
465 the uid and gid of the current process are taken).
466 setuid=value and setgid=value
468 Set the owner and group of all files.
469 mode=value
471 Set the mode of all files to value & 0777 disregarding the orig‐
472 inal permissions. Add search permission to directories that
473 have read permission. The value is given in octal.
474 protect
476 Do not allow any changes to the protection bits on the file sys‐
477 tem.
478 usemp Set uid and gid of the root of the file system to the uid and
480 gid of the mount point upon the first sync or umount, and then
481 clear this option. Strange...
482 verbose
484 Print an informational message for each successful mount.
485 prefix=string
487 Prefix used before volume name, when following a link.
488 volume=string
490 Prefix (of length at most 30) used before '/' when following a
491 symbolic link.
492 reserved=value
494 (Default: 2.) Number of unused blocks at the start of the
495 device.
496 root=value
498 Give explicitly the location of the root block.
499 bs=value
501 Give blocksize. Allowed values are 512, 1024, 2048, 4096.
502 grpquota / noquota / quota / usrquota
504 These options are accepted but ignored. (However, quota utili‐
505 ties may react to such strings in /etc/fstab.)
506
509 See the options section of the mount.cifs(8) man page (cifs-mount pack‐
510 age must be installed).
511
514 Just like nfs or smbfs implementation expects a binary argument to the
515 mount system call. This argument is constructed by mount.cifs(8) and
516 the current version of mount (2.12) does not know anything about cifs.
517
520 None.
521
524 The debugfs file system is a pseudo file system, traditionally mounted
525 on /sys/kernel/debug. There are no mount options.
526
529 The devpts file system is a pseudo file system, traditionally mounted
530 on /dev/pts. In order to acquire a pseudo terminal, a process opens
531 /dev/ptmx; the number of the pseudo terminal is then made available to
532 the process and the pseudo terminal slave can be accessed as
533 /dev/pts/<number>.
534 uid=value and gid=value
536 This sets the owner or the group of newly created PTYs to the
537 specified values. When nothing is specified, they will be set to
538 the UID and GID of the creating process. For example, if there
539 is a tty group with GID 5, then gid=5 will cause newly created
540 PTYs to belong to the tty group.
541 mode=value
543 Set the mode of newly created PTYs to the specified value. The
544 default is 0600. A value of mode=620 and gid=5 makes "mesg y"
545 the default on newly created PTYs.
546
549 None. Note that the `ext' file system is obsolete. Don't use it.
550 Since Linux version 2.1.21 extfs is no longer part of the kernel
551 source.
552
555 The `ext2' file system is the standard Linux file system. Since Linux
556 2.5.46, for most mount options the default is determined by the
557 filesystem superblock. Set them with tune2fs(8).
558 acl / noacl
560 Support POSIX Access Control Lists (or not).
561 bsddf / minixdf
563 Set the behaviour for the statfs system call. The minixdf behav‐
564 iour is to return in the f_blocks field the total number of
565 blocks of the file system, while the bsddf behaviour (which is
566 the default) is to subtract the overhead blocks used by the ext2
567 file system and not available for file storage. Thus
568 % mount /k -o minixdf; df /k; umount /k
570 Filesystem 1024-blocks Used Available Capacity Mounted on
571 /dev/sda6 2630655 86954 2412169 3% /k
572 % mount /k -o bsddf; df /k; umount /k
573 Filesystem 1024-blocks Used Available Capacity Mounted on
574 /dev/sda6 2543714 13 2412169 0% /k
575 (Note that this example shows that one can add command line options to
577 the options given in /etc/fstab.)
578 check=none / nocheck
581 No checking is done at mount time. This is the default. This is
582 fast. It is wise to invoke e2fsck(8) every now and then, e.g.
583 at boot time.
584 debug Print debugging info upon each (re)mount.
586 errors=continue / errors=remount-ro / errors=panic
588 Define the behaviour when an error is encountered. (Either
589 ignore errors and just mark the file system erroneous and con‐
590 tinue, or remount the file system read-only, or panic and halt
591 the system.) The default is set in the filesystem superblock,
592 and can be changed using tune2fs(8).
593 grpid or bsdgroups / nogrpid or sysvgroups
595 These options define what group id a newly created file gets.
596 When grpid is set, it takes the group id of the directory in
597 which it is created; otherwise (the default) it takes the fsgid
598 of the current process, unless the directory has the setgid bit
599 set, in which case it takes the gid from the parent directory,
600 and also gets the setgid bit set if it is a directory itself.
601 grpquota / noquota / quota / usrquota
603 These options are accepted but ignored.
604 nobh Do not attach buffer_heads to file pagecache. (Since 2.5.49.)
606 nouid32
608 Disables 32-bit UIDs and GIDs. This is for interoperability
609 with older kernels which only store and expect 16-bit values.
610 oldalloc or orlov
612 Use old allocator or Orlov allocator for new inodes. Orlov is
613 default.
614 resgid=n and resuid=n
616 The ext2 file system reserves a certain percentage of the avail‐
617 able space (by default 5%, see mke2fs(8) and tune2fs(8)). These
618 options determine who can use the reserved blocks. (Roughly:
619 whoever has the specified uid, or belongs to the specified
620 group.)
621 sb=n Instead of block 1, use block n as superblock. This could be
623 useful when the filesystem has been damaged. (Earlier, copies
624 of the superblock would be made every 8192 blocks: in block 1,
625 8193, 16385, ... (and one got thousands of copies on a big
626 filesystem). Since version 1.08, mke2fs has a -s (sparse
627 superblock) option to reduce the number of backup superblocks,
628 and since version 1.15 this is the default. Note that this may
629 mean that ext2 filesystems created by a recent mke2fs cannot be
630 mounted r/w under Linux 2.0.*.) The block number here uses 1k
631 units. Thus, if you want to use logical block 32768 on a
632 filesystem with 4k blocks, use "sb=131072".
633 user_xattr / nouser_xattr
635 Support "user." extended attributes (or not).
636
640 The `ext3' file system is a version of the ext2 file system which has
641 been enhanced with journalling. It supports the same options as ext2
642 as well as the following additions:
643 journal=update
645 Update the ext3 file system's journal to the current format.
646 journal=inum
648 When a journal already exists, this option is ignored. Other‐
649 wise, it specifies the number of the inode which will represent
650 the ext3 file system's journal file; ext3 will create a new
651 journal, overwriting the old contents of the file whose inode
652 number is inum.
653 noload Do not load the ext3 file system's journal on mounting.
655 data=journal / data=ordered / data=writeback
657 Specifies the journalling mode for file data. Metadata is
658 always journaled. To use modes other than ordered on the root
659 file system, pass the mode to the kernel as boot parameter, e.g.
660 rootflags=data=journal.
661 journal
663 All data is committed into the journal prior to being
664 written into the main file system.
665 ordered
667 This is the default mode. All data is forced directly
668 out to the main file system prior to its metadata being
669 committed to the journal.
670 writeback
672 Data ordering is not preserved - data may be written into
673 the main file system after its metadata has been commit‐
674 ted to the journal. This is rumoured to be the highest-
675 throughput option. It guarantees internal file system
676 integrity, however it can allow old data to appear in
677 files after a crash and journal recovery.
678 commit=nrsec
680 Sync all data and metadata every nrsec seconds. The default
681 value is 5 seconds. Zero means default.
682
685 (Note: fat is not a separate filesystem, but a common part of the
686 msdos, umsdos and vfat filesystems.)
687 blocksize=512 / blocksize=1024 / blocksize=2048
689 Set blocksize (default 512).
690 uid=value and gid=value
692 Set the owner and group of all files. (Default: the uid and gid
693 of the current process.)
694 umask=value
696 Set the umask (the bitmask of the permissions that are not
697 present). The default is the umask of the current process. The
698 value is given in octal.
699 dmask=value
701 Set the umask applied to directories only. The default is the
702 umask of the current process. The value is given in octal.
703 fmask=value
705 Set the umask applied to regular files only. The default is the
706 umask of the current process. The value is given in octal.
707 check=value
709 Three different levels of pickyness can be chosen:
710 r[elaxed]
712 Upper and lower case are accepted and equivalent, long
713 name parts are truncated (e.g. verylongname.foobar
714 becomes verylong.foo), leading and embedded spaces are
715 accepted in each name part (name and extension).
716 n[ormal]
718 Like "relaxed", but many special characters (*, ?, <,
719 spaces, etc.) are rejected. This is the default.
720 s[trict]
722 Like "normal", but names may not contain long parts and
723 special characters that are sometimes used on Linux, but
724 are not accepted by MS-DOS are rejected. (+, =, spaces,
725 etc.)
726 codepage=value
728 Sets the codepage for converting to shortname characters on FAT
729 and VFAT filesystems. By default, codepage 437 is used.
730 conv=b[inary] / conv=t[ext] / conv=a[uto]
732 The fat file system can perform CRLF<-->NL (MS-DOS text format
733 to UNIX text format) conversion in the kernel. The following
734 conversion modes are available:
735 binary no translation is performed. This is the default.
737 text CRLF<-->NL translation is performed on all files.
739 auto CRLF<-->NL translation is performed on all files that
741 don't have a "well-known binary" extension. The list of
742 known extensions can be found at the beginning of
743 fs/fat/misc.c (as of 2.0, the list is: exe, com, bin,
744 app, sys, drv, ovl, ovr, obj, lib, dll, pif, arc, zip,
745 lha, lzh, zoo, tar, z, arj, tz, taz, tzp, tpz, gz, tgz,
746 deb, gif, bmp, tif, gl, jpg, pcx, tfm, vf, gf, pk, pxl,
747 dvi).
748 Programs that do computed lseeks won't like in-kernel text con‐
750 version. Several people have had their data ruined by this
751 translation. Beware!
752 For file systems mounted in binary mode, a conversion tool
754 (fromdos/todos) is available.
755 cvf_format=module
757 Forces the driver to use the CVF (Compressed Volume File) module
758 cvf_module instead of auto-detection. If the kernel supports
759 kmod, the cvf_format=xxx option also controls on-demand CVF mod‐
760 ule loading.
761 cvf_option=option
763 Option passed to the CVF module.
764 debug Turn on the debug flag. A version string and a list of file
766 system parameters will be printed (these data are also printed
767 if the parameters appear to be inconsistent).
768 fat=12 / fat=16 / fat=32
770 Specify a 12, 16 or 32 bit fat. This overrides the automatic
771 FAT type detection routine. Use with caution!
772 iocharset=value
774 Character set to use for converting between 8 bit characters and
775 16 bit Unicode characters. The default is iso8859-1. Long file‐
776 names are stored on disk in Unicode format.
777 quiet Turn on the quiet flag. Attempts to chown or chmod files do not
779 return errors, although they fail. Use with caution!
780 sys_immutable, showexec, dots, nodots, dotsOK=[yes|no]
782 Various misguided attempts to force Unix or DOS conventions onto
783 a FAT file system.
784
787 creator=cccc, type=cccc
788 Set the creator/type values as shown by the MacOS finder used
789 for creating new files. Default values: '????'.
790 uid=n, gid=n
792 Set the owner and group of all files. (Default: the uid and gid
793 of the current process.)
794 dir_umask=n, file_umask=n, umask=n
796 Set the umask used for all directories, all regular files, or
797 all files and directories. Defaults to the umask of the current
798 process.
799 session=n
801 Select the CDROM session to mount. Defaults to leaving that
802 decision to the CDROM driver. This option will fail with any‐
803 thing but a CDROM as underlying device.
804 part=n Select partition number n from the device. Only makes sense for
806 CDROMS. Defaults to not parsing the partition table at all.
807 quiet Don't complain about invalid mount options.
809
812 uid=value and gid=value
813 Set the owner and group of all files. (Default: the uid and gid
814 of the current process.)
815 umask=value
817 Set the umask (the bitmask of the permissions that are not
818 present). The default is the umask of the current process. The
819 value is given in octal.
820 case=lower / case=asis
822 Convert all files names to lower case, or leave them. (Default:
823 case=lower.)
824 conv=binary / conv=text / conv=auto
826 For conv=text, delete some random CRs (in particular, all fol‐
827 lowed by NL) when reading a file. For conv=auto, choose more or
828 less at random between conv=binary and conv=text. For
829 conv=binary, just read what is in the file. This is the default.
830 nocheck
832 Do not abort mounting when certain consistency checks fail.
833
836 ISO 9660 is a standard describing a filesystem structure to be used on
837 CD-ROMs. (This filesystem type is also seen on some DVDs. See also the
838 udf filesystem.)
839 Normal iso9660 filenames appear in a 8.3 format (i.e., DOS-like
841 restrictions on filename length), and in addition all characters are in
842 upper case. Also there is no field for file ownership, protection,
843 number of links, provision for block/character devices, etc.
844 Rock Ridge is an extension to iso9660 that provides all of these unix
846 like features. Basically there are extensions to each directory record
847 that supply all of the additional information, and when Rock Ridge is
848 in use, the filesystem is indistinguishable from a normal UNIX file
849 system (except that it is read-only, of course).
850 norock Disable the use of Rock Ridge extensions, even if available. Cf.
852 map.
853 nojoliet
855 Disable the use of Microsoft Joliet extensions, even if avail‐
856 able. Cf. map.
857 check=r[elaxed] / check=s[trict]
859 With check=relaxed, a filename is first converted to lower case
860 before doing the lookup. This is probably only meaningful
861 together with norock and map=normal. (Default: check=strict.)
862 uid=value and gid=value
864 Give all files in the file system the indicated user or group
865 id, possibly overriding the information found in the Rock Ridge
866 extensions. (Default: uid=0,gid=0.)
867 map=n[ormal] / map=o[ff] / map=a[corn]
869 For non-Rock Ridge volumes, normal name translation maps upper
870 to lower case ASCII, drops a trailing `;1', and converts `;' to
871 `.'. With map=off no name translation is done. See norock.
872 (Default: map=normal.) map=acorn is like map=normal but also
873 apply Acorn extensions if present.
874 mode=value
876 For non-Rock Ridge volumes, give all files the indicated mode.
877 (Default: read permission for everybody.) Since Linux 2.1.37
878 one no longer needs to specify the mode in decimal. (Octal is
879 indicated by a leading 0.)
880 unhide Also show hidden and associated files. (If the ordinary files
882 and the associated or hidden files have the same filenames, this
883 may make the ordinary files inaccessible.)
884 block=[512|1024|2048]
886 Set the block size to the indicated value. (Default:
887 block=1024.)
888 conv=a[uto] / conv=b[inary] / conv=m[text] / conv=t[ext]
890 (Default: conv=binary.) Since Linux 1.3.54 this option has no
891 effect anymore. (And non-binary settings used to be very dan‐
892 gerous, possibly leading to silent data corruption.)
893 cruft If the high byte of the file length contains other garbage, set
895 this mount option to ignore the high order bits of the file
896 length. This implies that a file cannot be larger than 16MB.
897 session=x
899 Select number of session on multisession CD. (Since 2.3.4.)
900 sbsector=xxx
902 Session begins from sector xxx. (Since 2.3.4.)
903 The following options are the same as for vfat and specifying them only
905 makes sense when using discs encoded using Microsoft's Joliet exten‐
906 sions.
907 iocharset=value
909 Character set to use for converting 16 bit Unicode characters on
910 CD to 8 bit characters. The default is iso8859-1.
911 utf8 Convert 16 bit Unicode characters on CD to UTF-8.
913
916 iocharset=name
917 Character set to use for converting from Unicode to ASCII. The
918 default is to do no conversion. Use iocharset=utf8 for UTF8
919 translations. This requires CONFIG_NLS_UTF8 to be set in the
920 kernel .config file.
921 resize=value
923 Resize the volume to value blocks. JFS only supports growing a
924 volume, not shrinking it. This option is only valid during a
925 remount, when the volume is mounted read-write. The resize key‐
926 word with no value will grow the volume to the full size of the
927 partition.
928 nointegrity
930 Do not write to the journal. The primary use of this option is
931 to allow for higher performance when restoring a volume from
932 backup media. The integrity of the volume is not guaranteed if
933 the system abnormally abends.
934 integrity
936 Default. Commit metadata changes to the journal. Use this
937 option to remount a volume where the nointegrity option was pre‐
938 viously specified in order to restore normal behavior.
939 errors=continue / errors=remount-ro / errors=panic
941 Define the behaviour when an error is encountered. (Either
942 ignore errors and just mark the file system erroneous and con‐
943 tinue, or remount the file system read-only, or panic and halt
944 the system.)
945 noquota / quota / usrquota / grpquota
947 These options are accepted but ignored.
948
951 None.
952
955 See mount options for fat. If the msdos file system detects an incon‐
956 sistency, it reports an error and sets the file system read-only. The
957 file system can be made writeable again by remounting it.
958
961 Just like nfs, the ncpfs implementation expects a binary argument (a
962 struct ncp_mount_data) to the mount system call. This argument is con‐
963 structed by ncpmount(8) and the current version of mount (2.12) does
964 not know anything about ncpfs.
965
968 Instead of a textual option string, parsed by the kernel, the nfs file
969 system expects a binary argument of type struct nfs_mount_data. The
970 program mount itself parses the following options of the form
971 `tag=value', and puts them in the structure mentioned: rsize=n,
972 wsize=n, timeo=n, retrans=n, acregmin=n, acregmax=n, acdirmin=n,
973 acdirmax=n, actimeo=n, retry=n, port=n, mountport=n, mounthost=name,
974 mountprog=n, mountvers=n, nfsprog=n, nfsvers=n, namlen=n. The option
975 addr=n is accepted but ignored. Also the following Boolean options,
976 possibly preceded by no are recognized: bg, fg, soft, hard, intr,
977 posix, cto, ac, tcp, udp, lock. For details, see nfs(5).
978 Especially useful options include
980 rsize=32768,wsize=32768
982 This causes the NFS client to try to negotiate a buffer size up
983 to the size specified. A large buffer size does improve perfor‐
984 mance, but both the server and client have to support it. In
985 the case where one of these does not support the size specified,
986 the size negotiated will be the largest that both support.
987 intr This will allow NFS operations (on hard mounts) to be inter‐
989 rupted while waiting for a response from the server.
990 nolock Do not use locking. Do not start lockd.
992
995 Instead of a textual option string, parsed by the kernel, the nfs4 file
996 system expects a binary argument of type struct nfs4_mount_data. The
997 program mount itself parses the following options of the form
998 `tag=value', and puts them in the structure mentioned: rsize=n,
999 wsize=n, timeo=n, retrans=n, acregmin=n, acregmax=n, acdirmin=n,
1000 acdirmax=n, actimeo=n, retry=n, port=n, proto=n, clientaddr=n, sec=n.
1001 The option addr=n is accepted but ignored. Also the following Boolean
1002 options, possibly preceded by no are recognized: bg, fg, soft, hard,
1003 intr, cto, ac, For details, see nfs(5).
1004 Especially useful options include
1006 rsize=32768,wsize=32768
1008 This causes the NFS4 client to try to negotiate a buffer size up
1009 to the size specified. A large buffer size does improve perfor‐
1010 mance, but both the server and client have to support it. In
1011 the case where one of these does not support the size specified,
1012 the size negotiated will be the largest that both support.
1013 intr This will allow NFS4 operations (on hard mounts) to be inter‐
1015 rupted while waiting for a response from the server.
1016
1019 iocharset=name
1020 Character set to use when returning file names. Unlike VFAT,
1021 NTFS suppresses names that contain unconvertible characters.
1022 Deprecated.
1023 nls=name
1025 New name for the option earlier called iocharset.
1026 utf8 Use UTF-8 for converting file names.
1028 uni_xlate=[0|1|2]
1030 For 0 (or `no' or `false'), do not use escape sequences for
1031 unknown Unicode characters. For 1 (or `yes' or `true') or 2,
1032 use vfat-style 4-byte escape sequences starting with ":". Here 2
1033 give a little-endian encoding and 1 a byteswapped bigendian
1034 encoding.
1035 posix=[0|1]
1037 If enabled (posix=1), the file system distinguishes between
1038 upper and lower case. The 8.3 alias names are presented as hard
1039 links instead of being suppressed.
1040 uid=value, gid=value and umask=value
1042 Set the file permission on the filesystem. The umask value is
1043 given in octal. By default, the files are owned by root and not
1044 readable by somebody else.
1045
1048 uid=value and gid=value
1049 These options are recognized, but have no effect as far as I can
1050 see.
1051
1054 Ramfs is a memory based filesystem. Mount it and you have it. Unmount
1055 it and it is gone. Present since Linux 2.3.99pre4. There are no mount
1056 options.
1057
1060 Reiserfs is a journaling filesystem. The reiserfs mount options are
1061 more fully described at http://www.namesys.com/mount-options.html.
1062 conv Instructs version 3.6 reiserfs software to mount a version 3.5
1064 file system, using the 3.6 format for newly created objects.
1065 This file system will no longer be compatible with reiserfs 3.5
1066 tools.
1067 hash=rupasov / hash=tea / hash=r5 / hash=detect
1069 Choose which hash function reiserfs will use to find files
1070 within directories.
1071 rupasov
1073 A hash invented by Yury Yu. Rupasov. It is fast and pre‐
1074 serves locality, mapping lexicographically close file
1075 names to close hash values. This option should not be
1076 used, as it causes a high probability of hash collisions.
1077 tea A Davis-Meyer function implemented by Jeremy
1079 Fitzhardinge. It uses hash permuting bits in the name.
1080 It gets high randomness and, therefore, low probability
1081 of hash collisions at some CPU cost. This may be used if
1082 EHASHCOLLISION errors are experienced with the r5 hash.
1083 r5 A modified version of the rupasov hash. It is used by
1085 default and is the best choice unless the file system has
1086 huge directories and unusual file-name patterns.
1087 detect Instructs mount to detect which hash function is in use
1089 by examining the file system being mounted, and to write
1090 this information into the reiserfs superblock. This is
1091 only useful on the first mount of an old format file sys‐
1092 tem.
1093 hashed_relocation
1095 Tunes the block allocator. This may provide performance improve‐
1096 ments in some situations.
1097 no_unhashed_relocation
1099 Tunes the block allocator. This may provide performance improve‐
1100 ments in some situations.
1101 noborder
1103 Disable the border allocator algorithm invented by Yury Yu.
1104 Rupasov. This may provide performance improvements in some sit‐
1105 uations.
1106 nolog Disable journalling. This will provide slight performance
1108 improvements in some situations at the cost of losing reiserfs's
1109 fast recovery from crashes. Even with this option turned on,
1110 reiserfs still performs all journalling operations, save for
1111 actual writes into its journalling area. Implementation of
1112 nolog is a work in progress.
1113 notail By default, reiserfs stores small files and `file tails'
1115 directly into its tree. This confuses some utilities such as
1116 LILO(8). This option is used to disable packing of files into
1117 the tree.
1118 replayonly
1120 Replay the transactions which are in the journal, but do not
1121 actually mount the file system. Mainly used by reiserfsck.
1122 resize=number
1124 A remount option which permits online expansion of reiserfs par‐
1125 titions. Instructs reiserfs to assume that the device has num‐
1126 ber blocks. This option is designed for use with devices which
1127 are under logical volume management (LVM). There is a special
1128 resizer utility which can be obtained from
1129 ftp://ftp.namesys.com/pub/reiserfsprogs.
1130
1133 None.
1134
1137 Just like nfs, the smbfs implementation expects a binary argument (a
1138 struct smb_mount_data) to the mount system call. This argument is con‐
1139 structed by smbmount(8) and the current version of mount (2.12) does
1140 not know anything about smbfs.
1141
1144 None.
1145
1148 The following parameters accept a suffix k, m or g for Ki, Mi, Gi
1149 (binary kilo, mega and giga) and can be changed on remount.
1150 size=nbytes
1152 Override default maximum size of the filesystem. The size is
1153 given in bytes, and rounded down to entire pages. The default
1154 is half of the memory.
1155 nr_blocks=
1157 Set number of blocks.
1158 nr_inodes=
1160 Set number of inodes.
1161 mode= Set initial permissions of the root directory.
1163
1166 udf is the "Universal Disk Format" filesystem defined by the Optical
1167 Storage Technology Association, and is often used for DVD-ROM. See
1168 also iso9660.
1169 gid= Set the default group.
1171 umask= Set the default umask. The value is given in octal.
1173 uid= Set the default user.
1175 unhide Show otherwise hidden files.
1177 undelete
1179 Show deleted files in lists.
1180 nostrict
1182 Unset strict conformance.
1183 iocharset
1185 Set the NLS character set.
1186 bs= Set the block size. (May not work unless 2048.)
1188 novrs Skip volume sequence recognition.
1190 session=
1192 Set the CDROM session counting from 0. Default: last session.
1193 anchor=
1195 Override standard anchor location. Default: 256.
1196 volume=
1198 Override the VolumeDesc location. (unused)
1199 partition=
1201 Override the PartitionDesc location. (unused)
1202 lastblock=
1204 Set the last block of the filesystem.
1205 fileset=
1207 Override the fileset block location. (unused)
1208 rootdir=
1210 Override the root directory location. (unused)
1211
1214 ufstype=value
1215 UFS is a file system widely used in different operating systems.
1216 The problem are differences among implementations. Features of
1217 some implementations are undocumented, so its hard to recognize
1218 the type of ufs automatically. That's why the user must specify
1219 the type of ufs by mount option. Possible values are:
1220 old Old format of ufs, this is the default, read only.
1222 (Don't forget to give the -r option.)
1223 44bsd For filesystems created by a BSD-like system (Net‐
1225 BSD,FreeBSD,OpenBSD).
1226 sun For filesystems created by SunOS or Solaris on Sparc.
1228 sunx86 For filesystems created by Solaris on x86.
1230 hp For filesystems created by HP-UX, read-only.
1232 nextstep
1234 For filesystems created by NeXTStep (on NeXT station)
1235 (currently read only).
1236 nextstep-cd
1238 For NextStep CDROMs (block_size == 2048), read-only.
1239 openstep
1241 For filesystems created by OpenStep (currently read
1242 only). The same filesystem type is also used by Mac OS
1243 X.
1244 onerror=value
1247 Set behaviour on error:
1248 panic If an error is encountered, cause a kernel panic.
1250 [lock|umount|repair]
1252 These mount options don't do anything at present; when an
1253 error is encountered only a console message is printed.
1254
1257 See mount options for msdos. The dotsOK option is explicitly killed by
1258 umsdos.
1259
1262 First of all, the mount options for fat are recognized. The dotsOK
1263 option is explicitly killed by vfat. Furthermore, there are
1264 uni_xlate
1266 Translate unhandled Unicode characters to special escaped
1267 sequences. This lets you backup and restore filenames that are
1268 created with any Unicode characters. Without this option, a '?'
1269 is used when no translation is possible. The escape character is
1270 ':' because it is otherwise illegal on the vfat filesystem. The
1271 escape sequence that gets used, where u is the unicode charac‐
1272 ter, is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).
1273 posix Allow two files with names that only differ in case.
1275 nonumtail
1277 First try to make a short name without sequence number, before
1278 trying name~num.ext.
1279 utf8 UTF8 is the filesystem safe 8-bit encoding of Unicode that is
1281 used by the console. It can be be enabled for the filesystem
1282 with this option. If `uni_xlate' gets set, UTF8 gets disabled.
1283 shortname=[lower|win95|winnt|mixed]
1285 Defines the behaviour for creation and display of filenames
1287 which fit into 8.3 characters. If a long name for a file exists,
1288 it will always be preferred display. There are four modes:
1289 lower Force the short name to lower case upon display; store a
1291 long name when the short name is not all upper case.
1292 win95 Force the short name to upper case upon display; store a
1294 long name when the short name is not all upper case.
1295 winnt Display the shortname as is; store a long name when the
1297 short name is not all lower case or all upper case.
1298 mixed Display the short name as is; store a long name when the
1300 short name is not all upper case.
1301 The default is "lower".
1303
1306 devuid=uid and devgid=gid and devmode=mode
1307 Set the owner and group and mode of the device files in the
1308 usbfs file system (default: uid=gid=0, mode=0644). The mode is
1309 given in octal.
1310 busuid=uid and busgid=gid and busmode=mode
1312 Set the owner and group and mode of the bus directories in the
1313 usbfs file system (default: uid=gid=0, mode=0555). The mode is
1314 given in octal.
1315 listuid=uid and listgid=gid and listmode=mode
1317 Set the owner and group and mode of the file devices (default:
1318 uid=gid=0, mode=0444). The mode is given in octal.
1319
1322 None.
1323
1326 biosize=size
1327 Sets the preferred buffered I/O size (default size is 64K).
1328 size must be expressed as the logarithm (base2) of the desired
1329 I/O size. Valid values for this option are 14 through 16,
1330 inclusive (i.e. 16K, 32K, and 64K bytes). On machines with a 4K
1331 pagesize, 13 (8K bytes) is also a valid size. The preferred
1332 buffered I/O size can also be altered on an individual file
1333 basis using the ioctl(2) system call.
1334 dmapi / xdsm
1336 Enable the DMAPI (Data Management API) event callouts.
1337 logbufs=value
1339 Set the number of in-memory log buffers. Valid numbers range
1340 from 2-8 inclusive. The default value is 8 buffers for filesys‐
1341 tems with a blocksize of 64K, 4 buffers for filesystems with a
1342 blocksize of 32K, 3 buffers for filesystems with a blocksize of
1343 16K, and 2 buffers for all other configurations. Increasing the
1344 number of buffers may increase performance on some workloads at
1345 the cost of the memory used for the additional log buffers and
1346 their associated control structures.
1347 logbsize=value
1349 Set the size of each in-memory log buffer. Valid sizes are
1350 16384 (16K) and 32768 (32K). The default value for machines
1351 with more than 32MB of memory is 32768, machines with less mem‐
1352 ory use 16384 by default.
1353 logdev=device and rtdev=device
1355 Use an external log (metadata journal) and/or real-time device.
1356 An XFS filesystem has up to three parts: a data section, a log
1357 section, and a real-time section. The real-time section is
1358 optional, and the log section can be separate from the data sec‐
1359 tion or contained within it. Refer to xfs(5).
1360 noalign
1362 Data allocations will not be aligned at stripe unit boundaries.
1363 noatime
1365 Access timestamps are not updated when a file is read.
1366 norecovery
1368 The filesystem will be mounted without running log recovery. If
1369 the filesystem was not cleanly unmounted, it is likely to be
1370 inconsistent when mounted in norecovery mode. Some files or
1371 directories may not be accessible because of this. Filesystems
1372 mounted norecovery must be mounted read-only or the mount will
1373 fail.
1374 nouuid Ignore the filesystem uuid. This avoids errors for duplicate
1376 uuids.
1377 osyncisdsync
1379 Make writes to files opened with the O_SYNC flag set behave as
1380 if the O_DSYNC flag had been used instead. This can result in
1381 better performance without compromising data safety. However if
1382 this option is in effect, timestamp updates from O_SYNC writes
1383 can be lost if the system crashes.
1384 quota / usrquota / uqnoenforce
1386 User disk quota accounting enabled, and limits (optionally)
1387 enforced.
1388 grpquota / gqnoenforce
1390 Group disk quota accounting enabled and limits (optionally)
1391 enforced.
1392 sunit=value and swidth=value
1394 Used to specify the stripe unit and width for a RAID device or a
1395 stripe volume. value must be specified in 512-byte block units.
1396 If this option is not specified and the filesystem was made on a
1397 stripe volume or the stripe width or unit were specified for the
1398 RAID device at mkfs time, then the mount system call will
1399 restore the value from the superblock. For filesystems that are
1400 made directly on RAID devices, these options can be used to
1401 override the information in the superblock if the underlying
1402 disk layout changes after the filesystem has been created. The
1403 swidth option is required if the sunit option has been speci‐
1404 fied, and must be a multiple of the sunit value.
1405
1408 None. Although nothing is wrong with xiafs, it is not used much, and is
1409 not maintained. Probably one shouldn't use it. Since Linux version
1410 2.1.21 xiafs is no longer part of the kernel source.
1411
1414 One further possible type is a mount via the loop device. For example,
1415 the command
1416 mount /tmp/fdimage /mnt -t msdos -o loop=/dev/loop3,blocksize=1024
1418 will set up the loop device /dev/loop3 to correspond to the file
1420 /tmp/fdimage, and then mount this device on /mnt.
1421 This type of mount knows about three options, namely loop, offset and
1423 encryption, that are really options to losetup(8). (These options can
1424 be used in addition to those specific to the filesystem type.)
1425 If no explicit loop device is mentioned (but just an option `-o loop'
1427 is given), then mount will try to find some unused loop device and use
1428 that. If you are not so unwise as to make /etc/mtab a symbolic link to
1429 /proc/mounts then any loop device allocated by mount will be freed by
1430 umount. You can also free a loop device by hand, using `losetup -d',
1431 see losetup(8).
1432
1435 mount has the following return codes (the bits can be ORed):
1436 0 success
1438 1 incorrect invocation or permissions
1440 2 system error (out of memory, cannot fork, no more loop devices)
1442 4 internal mount bug or missing nfs support in mount
1444 8 user interrupt
1446 16 problems writing or locking /etc/mtab
1448 32 mount failure
1450 64 some mount succeeded
1452
1455 /etc/fstab file system table
1456 /etc/mtab table of mounted file systems
1458 /etc/mtab~ lock file
1460 /etc/mtab.tmp temporary file
1462 /etc/filesystems a list of filesystem types to try
1464
1467 mount(2), umount(2), fstab(5), umount(8), swapon(8), nfs(5), xfs(5),
1468 e2label(8), xfs_admin(8), mountd(8), nfsd(8), mke2fs(8), tune2fs(8),
1469 losetup(8)
1470
1472 It is possible for a corrupted file system to cause a crash.
1473 Some Linux file systems don't support -o sync and -o dirsync (the ext2,
1475 ext3, fat and vfat file systems do support synchronous updates (a la
1476 BSD) when mounted with the sync option).
1477 The -o remount may not be able to change mount parameters (all ext2fs-
1479 specific parameters, except sb, are changeable with a remount, for
1480 example, but you can't change gid or umask for the fatfs).
1481 Mount by label or uuid will work only if your devices have the names
1483 listed in /proc/partitions. In particular, it may well fail if the
1484 kernel was compiled with devfs but devfs is not mounted.
1485 It is possible that files /etc/mtab and /proc/mounts don't match. The
1487 first file is based only on the mount command options, but the content
1488 of the second file also depends on the kernel and others settings (e.g.
1489 remote NFS server. In particular case the mount command may reports
1490 unreliable information about a NFS mount point and the /proc/mounts
1491 file usually contains more reliable information.)
1492 Checking files on NFS filesystem referenced by file descriptors (i.e.
1494 the fcntl and ioctl families of functions) may lead to inconsistent
1495 result due to the lack of consistency check in kernel even if noac is
1496 used.
1497
1499 A mount command existed in Version 5 AT&T UNIX.
1500Linux 2.6 2004-12-16 MOUNT(8)