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!!NAME
mount - mount a file system

!!SYNOPSIS
__mount [[-lhV]__

__mount -a [[-fFnrsvw] [[-t __ ''vfstype'' __] [[-O __ ''optlist'' __]__
__mount [[-fnrsvw] [[-o __ ''options'' __ [[,...]] __ ''device '' __|__ '' dir''
__mount [[-fnrsvw] [[-t __ ''vfstype'' __] [[-o __ ''options'' __] __ ''device dir''

!!DESCRIPTION
All files accessible in a Unix system are arranged in one big tree, the file hierarchy, rooted at __/__ . These files can be spread out over several devices. The __mount__ command serves to attach the file system found on some device to the big file tree. Conversely, the umount(8) command will detach it again.

The standard form of the __mount__ command, is

 __mount -t__ '' type device dir''
This tells the kernel to attach the file system found on ''device'' (which is of type ''type'' ) at the directory ''dir'' . The previous contents (if any) and owner and mode of ''dir'' become invisible, and as long as this file system remains mounted, the pathname ''dir'' refers to the root of the file system on ''device'' .

Three forms of invocation do not actually mount anything:

 __mount -h__
prints a help message;

 __mount -V__
prints a version string; and just
 __mount [[-l] [[-t__ '' type'' __]__
lists all mounted file systems (of type ''type'' ). The option -l adds the (ext2, ext3 and XFS) labels in this listing. See below.

Since Linux 2.4.0 it is possible to remount part of the file hierarchy somewhere else. The call is

 __mount --bind olddir newdir__
After this call the same contents is accessible in two places.

This call attaches only (part of) a single filesystem, not possible submounts. The entire file hierarchy including submounts is attached a second place using

 __mount --rbind olddir newdir__


Since Linux 2.5.1 it is possible to atomically move a subtree to another place. The call is

 __mount --move olddir newdir__


The ''proc'' file system is not associated with a special device, and when mounting it, an arbitrary keyword, such as ''proc'' can be used instead of a device specification. (The customary choice ''none'' is less fortunate: the error message `none busy' from __umount__ can be confusing.)

Most devices are indicated by a file name (of a block special device), like ''/dev/sda1'' , but there are other possibilities. For example, in the case of an NFS mount, ''device'' may look like ''knuth.cwi.nl:/dir'' . It is possible to indicate a block special device using its volume label or UUID (see the -L and -U options below).

The file ''/etc/fstab'' (see fstab(5)), may contain lines describing what devices are usually mounted where, using which options. This file is used in three ways:


(i) The command

 __mount -a [[-t __ ''type'' __] [[-O __ ''optlist'' __]__
(usually given in a bootscript) causes all file systems mentioned in ''fstab'' (of the proper type and/or having or not having the proper options) to be mounted as indicated, except for those whose line contains the __noauto__ keyword. Adding the __-F__ option will make mount fork, so that the filesystems are mounted simultaneously.

(ii) When mounting a file system mentioned in ''fstab'' , it suffices to give only the device, or only the mount point.

(iii) Normally, only the superuser can mount file systems. However, when ''fstab'' contains the __user__ option on a line, then anybody can mount the corresponding system.

Thus, given a line

 __/dev/cdrom  /cd  iso9660  ro,user,noauto,unhide__
any user can mount the iso9660 file system found on his CDROM using the command

 __mount /dev/cdrom__
or

 __mount /cd__
For more details, see fstab(5). Only the user that mounted a filesystem can unmount it again. If any user should be able to unmount, then use __users__ instead of __user__ in the ''fstab'' line. The __owner__ option is similar to the __user__ option, with the restriction that the user must be the owner of the special file. This may be useful e.g. for ''/dev/fd'' if a login script makes the console user owner of this device.

The programs __mount__ and __umount__ maintain a list of currently mounted file systems in the file ''/etc/mtab'' . If no arguments are given to __mount__ , this list is printed.

When the ''proc'' filesystem is mounted (say at ''/proc'' ), the files ''/etc/mtab'' and ''/proc/mounts'' have very similar contents. The former has somewhat more information, such as the mount options used, but is not necessarily up-to-date (cf. the __-n__ option below). It is possible to replace ''/etc/mtab'' by a symbolic link to ''/proc/mounts'' , but some information is lost that way, and in particular working with the loop device will be less convenient, and using the "user" option will fail.


!!OPTIONS
The full set of options used by an invocation of __mount__ is determined by first extracting the options for the file system from the ''fstab'' table, then applying any options specified by the __-o__ argument, and finally applying a __-r__  or  __-w__ option, when present.

Options available for the __mount__ command:
;__-V__ : Output version.
;__-h__ : Print a help message.
;__-v__ : Verbose mode.
;__-p "''num''"__  : If the mount requires a passphrase to be entered, read it from file descriptor ''num''  instead of from the terminal.
;__-a__ : Mount all filesystems (of the given types) mentioned in ''fstab'' .
;__-F__ : (Used in conjunction with __-a__ .) Fork off a new incarnation of mount for each device. This will do the mounts on different devices or different NFS servers in parallel. This has the advantage that it is faster; also NFS timeouts go in parallel. A disadvantage is that the mounts are done in undefined order. Thus, you cannot use this option if you want to mount both ''/usr'' and ''/usr/spool'' .
;__-f__ : Causes everything to be done except for the actual system call; if it's not obvious, this "fakes" mounting the file system.  This option is useful in conjunction with the __-v__ flag to determine what the __mount__ command is trying to do. It can also be used to add entries for devices that were mounted earlier with the -n option.
;__-i__ : Don't call the /sbin/mount.<filesystem> helper even if it exists.
;__-l__ : Add the ext2, ext3 and XFS labels in the mount output. Mount must have permission to read the disk device (e.g. be suid root) for this to work. One can set such a label for ext2 or ext3 using the e2label(8) utility, or for XFS using xfs_admin(8).
;__-n__ : Mount without writing in ''/etc/mtab'' . This is necessary for example when ''/etc'' is on a read-only file system.
;__-s__ : Tolerate sloppy mount options rather than failing. This will ignore mount options not supported by a filesystem type. Not all filesystems support this option. This option exists for support of the Linux autofs-based automounter.
;__-r__ : Mount the file system read-only. A synonym is __-o ro__ .
;__-w__ : Mount the file system read/write. This is the default. A synonym is __-o rw__ .
;__-L__ '' label'' : Mount the partition that has the specified ''label'' .
;__-U__ '' uuid'' : Mount the partition that has the specified ''uuid'' . These two options require the file ''/proc/partitions'' (present since Linux 2.1.116) to exist.
;__-t__ '' vfstype'' : The argument following the __-t__ is used to indicate the file system type.  The file system types which are currently supported are: ''adfs'' , ''affs'' , ''autofs'' , ''coda'' , ''coherent'' , ''cramfs'' , ''devpts'' , ''efs'' , ''ext'' , ''ext2'' , ''ext3'' , ''hfs'' , ''hpfs'' , ''iso9660'' , ''jfs'' , ''minix'' , ''msdos'' , ''ncpfs'' , ''nfs'' , ''ntfs'' , ''proc'' , ''qnx4'' , ''ramfs'' , ''reiserfs'' , ''romfs'' , ''smbfs'' , ''sysv'' , ''tmpfs'' , ''udf'' , ''ufs'' , ''umsdos'' , ''vfat'' , ''xenix'' , ''xfs'' , ''xiafs'' . Note that coherent, sysv and xenix are equivalent and that ''xenix'' and ''coherent'' will be removed at some point in the future \(em use ''sysv'' instead. Since kernel version 2.1.21 the types ''ext'' and ''xiafs'' do not exist anymore.

For most types all the __mount__ program has to do is issue a simple mount(2) system call, and no detailed knowledge of the filesystem type is required. For a few types however (like nfs, smbfs, ncpfs) ad hoc code is necessary. The nfs ad hoc code is built in, but smbfs and ncpfs have a separate mount program. In order to make it possible to treat all types in a uniform way, mount will execute the program ''/sbin/mount.TYPE'' (if that exists) when called with type ''TYPE'' . Since various versions of the ''smbmount'' program have different calling conventions, ''/sbin/mount.smb'' may have to be a shell script that sets up the desired call.


The type ''iso9660'' is the default.  If no __-t__ option is given, or if the __auto__ type is specified, the superblock is probed for the filesystem type ( ''adfs'' , ''bfs'' , ''cramfs'' , ''ext'' , ''ext2'' , ''ext3'' , ''hfs'' , ''hpfs'' , ''iso9660'' , ''jfs'' , ''minix'' , ''ntfs'' , ''qnx4'' , ''reiserfs'' , ''romfs'' , ''udf'' , ''ufs'' , ''vxfs'' , ''xfs'' , ''xiafs'' are supported). If this probe fails, mount will try to read the file ''/etc/filesystems'' , or, if that does not exist, ''/proc/filesystems'' . All of the filesystem types listed there will be tried, except for those that are labeled "nodev" (e.g., ''devpts'' , ''proc'' and ''nfs'' ). If ''/etc/filesystems'' ends in a line with a single * only, mount will read ''/proc/filesystems'' afterwards.

The __auto__ type may be useful for user-mounted floppies. Creating a file ''/etc/filesystems'' can be useful to change the probe order (e.g., to try vfat before msdos) or if you use a kernel module autoloader. Warning: the probing uses a heuristic (the presence of appropriate `magic'), and could recognize the wrong filesystem type, possibly with catastrophic consequences. If your data is valuable, don't ask __mount__ to guess.

More than one type may be specified in a comma separated list.  The list of file system types can be prefixed with __no__ to specify the file system types on which no action should be taken. (This can be meaningful with the __-a__ option.)

For example, the command:

  __mount -a -t nomsdos,ext__
mounts all file systems except those of type  ''msdos''  and  ''ext'' .

;__-O__ : Used in conjunction with __-a__ , to limit the set of filesystems to which the __-a__ is applied.  Like __-t__ in this regard except that it is useless except in the context of __-a__ . For example, the command:

  __mount -a -O no_netdev__
mounts all file systems except those which have the option  ''_netdev''  specified in the options field in the  ''/etc/fstab''  file.
It is different from  __-t__  in that each option is matched exactly; a leading  __no__  at the beginning of one option does not negate the rest.
The  __-t__  and  __-O__  options are cumulative in effect; that is, the command
  __mount -a -t ext2 -O _netdev__
mounts all ext2 filesystems with the _netdev option, not all filesystems  that are either ext2 or have the _netdev option specified.

;__-o__ : Options are specified with a __-o__ flag followed by a comma separated string of options. Some of these options are only useful when they appear in the ''/etc/fstab'' file.  The following options apply to any file system that is being mounted (but not every file system actually honors them - e.g., the __sync__ option today has effect only for ext2, ext3 and ufs):

;__async__ : All I/O to the file system should be done asynchronously.
;__atime__ : Update inode access time for each access. This is the default.
;__auto__ : Can be mounted with the __-a__ option.
;__defaults__ : Use default options: __rw__ ,  __suid__ ,  __dev__ ,  __exec__ ,  __auto__ ,  __nouser__ , and  __async.__
;__dev__ : Interpret character or block special devices on the file system.
;__exec__ : Permit execution of binaries.
;___netdev__ : The filesystem resides on a device that requires network access (used to prevent the system from attempting to mount these filesystems until the network has been enabled on the system).
;__noatime__ : Do not update inode access times on this file system (e.g, for faster access on the news spool to speed up news servers).
;__noauto__ : Can only be mounted explicitly (i.e., the __-a__ option will not cause the file system to be mounted).
;__nodev__ : Do not interpret character or block special devices on the file system.
;__noexec__ : Do not allow execution of any binaries on the mounted file system. This option might be useful for a server that has file systems containing binaries for architectures other than its own.
;__nosuid__ : Do not allow set-user-identifier or set-group-identifier bits to take effect. (This seems safe, but is in fact rather unsafe if you have suidperl(1) installed.)
;__nouser__ : Forbid an ordinary (i.e., non-root) user to mount the file system. This is the default.
;__remount__ : Attempt to remount an already-mounted file system.  This is commonly used to change the mount flags for a file system, especially to make a readonly file system writeable. It does not change device or mount point.
;__ro__ : Mount the file system read-only.
;__rw__ : Mount the file system read-write.
;__suid__ : Allow set-user-identifier or set-group-identifier bits to take effect.
;__sync__ : All I/O to the file system should be done synchronously.
;__dirsync__ : All directory updates within the file system should be done synchronously. This affects the following system calls: creat, link, unlink, symlink, mkdir, rmdir, mknod and rename.
;__user__ : Allow an ordinary user to mount the file system. The name of the mounting user is written to mtab so that he can unmount the file system again. This option implies the options __noexec__ ,  __nosuid__ , and  __nodev__ (unless overridden by subsequent options, as in the option line __user,exec,dev,suid__ ).
;__users__ : Allow every user to mount and unmount the file system. This option implies the options __noexec__ ,  __nosuid__ , and  __nodev__ (unless overridden by subsequent options, as in the option line __users,exec,dev,suid__ ).
;__encryption__ : Specifies an encryption algorithm to use.  Used in conjunction with the __loop__  option.
;__keybits__ : Specifies the key size to use for an encryption algorithm. Used in conjunction with the __loop__  and  __encryption__  options.

;__- bind__ : Remount a subtree somewhere else (so that its contents are available in both places). See above.
;__- move__ : Move a subtree to some other place. See above.





!!FILESYSTEM SPECIFIC MOUNT OPTIONS
The following options apply only to certain file systems. We sort them by file system. They all follow the __-o__ flag.

!!Mount options for adfs

;__uid=__''value'' and __gid=__''value'' : Set the owner and group of the files in the file system (default: uid=gid=0).
;__ownmask=__''value'' and __othmask=__''value'' : Set the permission mask for ADFS 'owner' permissions and 'other' permissions, respectively (default: 0700 and 0077, respectively). See also ''/usr/src/linux/Documentation/filesystems/adfs.txt'' .

!!Mount options for affs

;__uid=__''value'' and __gid=__''value'' : Set the owner and group of the root of the file system (default: uid=gid=0, but with option __uid__ or __gid__ without specified value, the uid and gid of the current process are taken).
;__setuid=__''value'' and __setgid=__''value'' : Set the owner and group of all files.
;__mode=__ ''value'' : Set the mode of all files to ''value''  & 0777 disregarding the original permissions. Add search permission to directories that have read permission. The value is given in octal.
;__protect__ : Do not allow any changes to the protection bits on the file system.
;__usemp__ : Set uid and gid of the root of the file system to the uid and gid of the mount point upon the first sync or umount, and then clear this option. Strange...
;__verbose__ : Print an informational message for each successful mount.
;__prefix=__ ''string'' : Prefix used before volume name, when following a link.
;__volume=__ ''string'' : Prefix (of length at most 30) used before '/' when following a symbolic link.
;__reserved=__ ''value'' : (Default: 2.) Number of unused blocks at the start of the device.
;__root=__ ''value'' : Give explicitly the location of the root block.
;__bs=__ ''value'' : Give blocksize. Allowed values are 512, 1024, 2048, 4096.
;__grpquota__  /  __noquota__  /  __quota__  /  __usrquota__ : These options are accepted but ignored. (However, quota utilities may react to such strings in ''/etc/fstab'' .)



!!Mount options for coherent
None.



!!Mount options for devpts
The devpts file system is a pseudo file system, traditionally mounted on ''/dev/pts'' . In order to acquire a pseudo terminal, a process opens ''/dev/ptmx'' ; the number of the pseudo terminal is then made available to the process and the pseudo terminal slave can be accessed as ''/dev/pts/'' <number>.
;__uid=__''value'' and __gid=__''value'' : This sets the owner or the group of newly created PTYs to the specified values. When nothing is specified, they will be set to the UID and GID of the creating process. For example, if there is a tty group with GID 5, then __gid=5__ will cause newly created PTYs to belong to the tty group.
;__mode=__ ''value'' : Set the mode of newly created PTYs to the specified value. The default is 0600. A value of  __mode=620__ and  __gid=5__ makes "mesg y" the default on newly created PTYs.



!!Mount options for ext
None. Note that the `ext' file system is obsolete. Don't use it. Since Linux version 2.1.21 extfs is no longer part of the kernel source.



!!Mount options for ext2
The `ext2' file system is the standard Linux file system. Due to a kernel bug, it may be mounted with random mount options (fixed in Linux 2.0.4).
;__bsddf__  /  __minixdf__ : Set the behaviour for the ''statfs'' system call. The __minixdf__ behaviour is to return in the ''f_blocks'' field the total number of blocks of the file system, while the __bsddf__ behaviour (which is the default) is to subtract the overhead blocks used by the ext2 file system and not available for file storage. Thus

 % mount /k -o minixdf; df /k; umount /k
 Filesystem   1024-blocks  Used Available Capacity Mounted on
 /dev/sda6      2630655   86954  2412169      3%   /k
 % mount /k -o bsddf; df /k; umount /k
 Filesystem   1024-blocks  Used Available Capacity Mounted on
 /dev/sda6      2543714      13  2412169      0%   /k


(Note that this example shows that one can add command line options to the options given in ''/etc/fstab'' .)


;__check__  /  __check=normal__  /  __check=strict__ : Set checking level. When at least one of these options is set (and __check=normal__ is set by default) the inodes and blocks bitmaps are checked upon mount (which can take half a minute or so on a big disk, and is rather useless). With strict checking, block deallocation checks that the block to free is in the data zone.
;__check=none__  /  __nocheck__ : No checking is done. This is fast. Recent kernels do not have a check option anymore - checking with e2fsck(8) is more meaningful.
;__debug__ : Print debugging info upon each (re)mount.
;__errors=continue__  /  __errors=remount-ro__  /  __errors=panic__ : Define the behaviour when an error is encountered. (Either ignore errors and just mark the file system erroneous and continue, or remount the file system read-only, or panic and halt the system.) The default is set in the filesystem superblock, and can be changed using tune2fs(8).
;__grpid__  or  __bsdgroups__  /  __nogrpid__  or  __sysvgroups__ : These options define what group id a newly created file gets. When __grpid__ is set, it takes the group id of the directory in which it is created; otherwise (the default) it takes the fsgid of the current process, unless the directory has the setgid bit set, in which case it takes the gid from the parent directory, and also gets the setgid bit set if it is a directory itself.
;__resgid=__''n'' and __resuid=__''n'' : The ext2 file system reserves a certain percentage of the available space (by default 5%, see mke2fs(8) and tune2fs(8)). These options determine who can use the reserved blocks. (Roughly: whoever has the specified uid, or belongs to the specified group.)
;__sb=__ ''n'' : Instead of block 1, use block ''n'' as superblock. This could be useful when the filesystem has been damaged. (Earlier, copies of the superblock would be made every 8192 blocks: in block 1, 8193, 16385, ... (and one got hundreds or even thousands of copies on a big filesystem). Since version 1.08, __mke2fs__ has a -s (sparse superblock) option to reduce the number of backup superblocks, and since version 1.15 this is the default. Note that this may mean that ext2 filesystems created by a recent __mke2fs__ cannot be mounted r/w under Linux 2.0.*.) The block number here uses 1k units. Thus, if you want to use logical block 32768 on a filesystem with 4k blocks, use "sb=131072".
;__grpquota__  /  __noquota__  /  __quota__  /  __usrquota__ : These options are accepted but ignored.


;__nouid32__ : Disables 32-bit UIDs and GIDs.  This is for interoperability with older kernels which only store and expect 16-bit values.





!!Mount options for ext3
The `ext3' file system is version of the ext2 file system which has been enhanced with journalling.  It supports the same options as ext2 as well as the following additions:
;__journal=update__ : Update the ext3 file system's journal to the current format.
;__journal=inum__ : When a journal already exists, this option is ignored. Otherwise, it specifies the number of the inode which will represent the ext3 file system's journal file;  ext3 will create a new journal, overwriting the old contents of the file whose inode number is ''inum'' .
;__noload__ : Do not load the ext3 file system's journal on mounting.
;__data=journal__  /  __data=ordered__  /  __data=writeback__ : Specifies the journalling mode for file data.  Metadata is always journaled.

;__journal__ : All data is committed into the journal prior to being written into the main file system.
;__ordered__ : This is the default mode.  All data is forced directly out to the main file system prior to its metadata being committed to the journal.
;__writeback__ : Data ordering is not preserved - data may be written into the main file system after its metadata has been committed to the journal. This is rumoured to be the highest-throughput option.  It guarantees internal file system integrity, however it can allow old data to appear in files after a crash and journal recovery.



!!Mount options for fat
(Note: ''fat'' is not a separate filesystem, but a common part of the ''msdos'' , ''umsdos'' and ''vfat'' filesystems.)
;__blocksize=512__  /  __blocksize=1024__  /  __blocksize=2048__ : Set blocksize (default 512).
;__uid=__''value'' and __gid=__''value'' : Set the owner and group of all files. (Default: the uid and gid of the current process.)
;__umask=__ ''value'' : Set the umask (the bitmask of the permissions that are __not__ present). The default is the umask of the current process. The value is given in octal.
;__dmask=__ ''value'' : Set the umask applied to directories only. The default is the umask of the current process. The value is given in octal. Present since 2.5.43.
;__fmask=__ ''value'' : Set the umask applied to regular files only. The default is the umask of the current process. The value is given in octal. Present since 2.5.43.
;__check=__ ''value'' : Three different levels of pickyness can be chosen:


;__r[[elaxed]__ : Upper and lower case are accepted and equivalent, long name parts are truncated (e.g. ''verylongname.foobar'' becomes ''verylong.foo'' ), leading and embedded spaces are accepted in each name part (name and extension).
;__n[[ormal]__ : Like "relaxed", but many special characters (*, ?, <, spaces, etc.) are rejected.  This is the default.
;__s[[trict]__ : Like "normal", but names may not contain long parts and special characters that are sometimes used on Linux, but are not accepted by MS-DOS are rejected. (+, =, spaces, etc.)

;__codepage=__ ''value'' : Sets the codepage for converting to shortname characters on FAT and VFAT filesystems. By default, codepage 437 is used.
;__conv=b[[inary]__  /  __conv=t[[ext]__  /  __conv=a[[uto]__ : The ''fat'' file system can perform CRLF<-->NL (MS-DOS text format to UNIX text format) conversion in the kernel. The following conversion modes are available:

;__binary__ : no translation is performed.  This is the default.
;__text__ : CRLF<-->NL translation is performed on all files.
;__auto__ : CRLF<-->NL translation is performed on all files that don't have a "well-known binary" extension. The list of known extensions can be found at the beginning of ''fs/fat/misc.c'' (as of 2.0, the list is: exe, com, bin, app, sys, drv, ovl, ovr, obj, lib, dll, pif, arc, zip, lha, lzh, zoo, tar, z, arj, tz, taz, tzp, tpz, gz, tgz, deb, gif, bmp, tif, gl, jpg, pcx, tfm, vf, gf, pk, pxl, dvi).

Programs that do computed lseeks won't like in-kernel text conversion. Several people have had their data ruined by this translation. Beware!

For file systems mounted in binary mode, a conversion tool (fromdos/todos) is available.

;__cvf_format=__ ''module'' : Forces the driver to use the CVF (Compressed Volume File) module cvf_ ''module'' instead of auto-detection. If the kernel supports kmod, the cvf_format=xxx option also controls on-demand CVF module loading.
;__cvf_option=__ ''option'' : Option passed to the CVF module.
;__debug__ : Turn on the ''debug'' flag.  A version string and a list of file system parameters will be printed (these data are also printed if the parameters appear to be inconsistent).
;__fat=12__  /  __fat=16__  /  __fat=32__ : Specify a 12, 16 or 32 bit fat.  This overrides the automatic FAT type detection routine.  Use with caution!
;__iocharset=__ ''value'' : Character set to use for converting between 8 bit characters and 16 bit Unicode characters. The default is iso8859-1. Long filenames are stored on disk in Unicode format.
;__quiet__ : Turn on the ''quiet'' flag.  Attempts to chown or chmod files do not return errors, although they fail. Use with caution!
;__sys_immutable, showexec, dots, nodots, dotsOK=[[yes|no]__ : Various misguided attempts to force Unix or DOS conventions onto a FAT file system.



!!Mount options for hpfs

;__uid=__''value'' and __gid=__''value'' : Set the owner and group of all files. (Default: the uid and gid of the current process.)
;__umask=__ ''value'' : Set the umask (the bitmask of the permissions that are __not__ present). The default is the umask of the current process. The value is given in octal.
;__case=lower__  /  __case=asis__ : Convert all files names to lower case, or leave them. (Default: __case=lower__ .)
;__conv=binary__  /  __conv=text__  /  __conv=auto__ : For __conv=text__ , delete some random CRs (in particular, all followed by NL) when reading a file. For __conv=auto__ , choose more or less at random between __conv=binary__  and  __conv=text__ . For __conv=binary__ , just read what is in the file. This is the default.
;__nocheck__ : Do not abort mounting when certain consistency checks fail.



!!Mount options for iso9660
ISO 9660 is a standard describing a filesystem structure to be used on CD-ROMs. (This filesystem type is also seen on some DVDs. See also the ''udf'' filesystem.)

Normal ''iso9660'' filenames appear in a 8.3 format (i.e., DOS-like restrictions on filename length), and in addition all characters are in upper case.  Also there is no field for file ownership, protection, number of links, provision for block/character devices, etc.

Rock Ridge is an extension to iso9660 that provides all of these unix like features.  Basically there are extensions to each directory record that supply all of the additional information, and when Rock Ridge is in use, the filesystem is indistinguishable from a normal UNIX file system (except that it is read-only, of course).
;__norock__ : Disable the use of Rock Ridge extensions, even if available. Cf. __map__ .
;__nojoliet__ : Disable the use of Microsoft Joliet extensions, even if available. Cf. __map__ .
;__check=r[[elaxed]__  /  __check=s[[trict]__ : With __check=relaxed__ , a filename is first converted to lower case before doing the lookup. This is probably only meaningful together with __norock__ and __map=normal__ . (Default: __check=strict__ .)
;__uid=__''value'' and __gid=__''value'' : Give all files in the file system the indicated user or group id, possibly overriding the information found in the Rock Ridge extensions. (Default: __uid=0,gid=0__ .)
;__map=n[[ormal]__  /  __map=o[[ff]__  /  __map=a[[corn]__ : For non-Rock Ridge volumes, normal name translation maps upper to lower case ASCII, drops a trailing `;1', and converts `;' to `.'. With __map=off__ no name translation is done. See __norock__ . (Default: __map=normal__ .) __map=acorn__ is like __map=normal__ but also apply Acorn extensions if present.
;__mode=__ ''value'' : For non-Rock Ridge volumes, give all files the indicated mode. (Default: read permission for everybody.) Since Linux 2.1.37 one no longer needs to specify the mode in decimal. (Octal is indicated by a leading 0.)
;__unhide__ : Also show hidden and associated files.
;__block=[[512|1024|2048]__ : Set the block size to the indicated value. (Default: __block=1024__ .)

;__conv=a[[uto]__  /  __conv=b[[inary]__  /  __conv=m[[text]__  /  __conv=t[[ext]__ : (Default: __conv=binary__ .) Since Linux 1.3.54 this option has no effect anymore. (And non-binary settings used to be very dangerous, possibly leading to silent data corruption.)
;__cruft__ : If the high byte of the file length contains other garbage, set this mount option to ignore the high order bits of the file length. This implies that a file cannot be larger than 16MB. The `cruft' option is set automatically if the entire CDROM has a weird size (negative, or more than 800MB). It is also set when volume sequence numbers other than 0 or 1 are seen.
;__session=__ ''x'' : Select number of session on multisession CD. (Since 2.3.4.)
;__sbsector=__ ''xxx'' : Session begins from sector xxx. (Since 2.3.4.)

The following options are the same as for vfat and specifying them only makes sense when using discs encoded using Microsoft's Joliet extensions.
;__iocharset=__ ''value'' : Character set to use for converting 16 bit Unicode characters on CD to 8 bit characters. The default is iso8859-1.
;__utf8__ : Convert 16 bit Unicode characters on CD to UTF-8.



!!Mount options for minix
None.



!!Mount options for msdos
See mount options for fat. If the ''msdos'' file system detects an inconsistency, it reports an error and sets the file system read-only. The file system can be made writeable again by remounting it.



!!Mount options for ncp
Just like ''nfs'' , the  ''ncp'' implementation expects a binary argument (a ''struct ncp_mount_data'' ) to the mount system call. This argument is constructed by ncpmount(8) and the current version of __mount__ (2.6h) does not know anything about ncp.



!!Mount options for nfs
Instead of a textual option string, parsed by the kernel, the ''nfs'' file system expects a binary argument of type ''struct nfs_mount_data'' . The program __mount__ itself parses the following options of the form `tag=value', and puts them in the structure mentioned: __rsize=__ ''n,'' __wsize=__ ''n,'' __timeo=__ ''n,'' __retrans=__ ''n,'' __acregmin=__ ''n,'' __acregmax=__ ''n,'' __acdirmin=__ ''n,'' __acdirmax=__ ''n,'' __actimeo=__ ''n,'' __retry=__ ''n,'' __port=__ ''n,'' __mountport=__ ''n,'' __mounthost=__ ''name,'' __mountprog=__ ''n,'' __mountvers=__ ''n,'' __nfsprog=__ ''n,'' __nfsvers=__ ''n,'' __namlen=__ ''n.'' The option __addr=__ ''n'' is accepted but ignored. Also the following Boolean options, possibly preceded by __no__ are recognized: __bg__ , __fg__ , __soft__ , __hard__ , __intr__ , __posix__ , __cto__ , __ac__ , __tcp__ , __udp__ , __lock__ . For details, see nfs(5).

Especially useful options include
;__rsize=8192,wsize=8192__ : This will make your nfs connection faster than with the default buffer size of 4096. (NFSv2 does not work with larger values of __rsize__ and __wsize__ .)
;__hard__ : The program accessing a file on a NFS mounted file system will hang when the server crashes. The process cannot be interrupted or killed unless you also specify __intr__ . When the NFS server is back online the program will continue undisturbed from where it was. This is probably what you want.
;__soft__ : This option allows the kernel to time out if the nfs server is not responding for some time. The time can be specified with __timeo=time__ . This option might be useful if your nfs server sometimes doesn't respond or will be rebooted while some process tries to get a file from the server. Usually it just causes lots of trouble.
;__nolock__ : Do not use locking. Do not start lockd.



!!Mount options for ntfs

;__iocharset=__ ''name'' : Character set to use when returning file names. Unlike VFAT, NTFS suppresses names that contain unconvertible characters.
;__utf8__ : Use UTF-8 for converting file names.
;__uni_xlate=[[0|1|2]__ : For 0 (or `no' or `false'), do not use escape sequences for unknown Unicode characters. For 1 (or `yes' or `true') or 2, use vfat-style 4-byte escape sequences starting with ":". Here 2 give a little-endian encoding and 1 a byteswapped bigendian encoding.
;__posix=[[0|1]__ : If enabled (posix=1), the file system distinguishes between upper and lower case. The 8.3 alias names are presented as hard links instead of being suppressed.
;__uid=__''value'', __gid=__''value'' and __umask=__''value'' : Set the file permission on the filesystem. The umask value is given in octal. By default, the files are owned by root and not readable by somebody else.



!!Mount options for proc

;__uid=__''value'' and __gid=__''value'' : These options are recognized, but have no effect as far as I can see.


!!Mount options for ramfs
Ramfs is a memory based filesystem. Mount it and you have it. Unmount it and it is gone. Present since Linux 2.3.99pre4. There are no mount options.



!!Mount options for reiserfs
Reiserfs is a journaling filesystem. The reiserfs mount options are more fully described at ''http://www.namesys.com/mount-options.html'' .
;__conv__ : Instructs version 3.6 reiserfs software to mount a version 3.5 file system, using the 3.6 format for newly created objects. This file system will no longer be compatible with reiserfs 3.5 tools.
;__hash=rupasov__  /  __hash=tea__  /  __hash=r5__  /  __hash=detect__ : Choose which hash function reiserfs will use to find files within directories.
;__rupasov__ : A hash invented by Yury Yu. Rupasov.  It is fast and preserves locality, mapping lexicographically close file names to close hash values. This option should not be used, as it causes a high probability of hash collisions.
;__tea__ : A Davis-Meyer function implemented by Jeremy Fitzhardinge. It uses hash permuting bits in the name.  It gets high randomness and, therefore, low probability of hash collisions at come CPU cost. This may be used if EHASHCOLLISION errors are experienced with the r5 hash.
;__r5__ : A modified version of the rupasov hash. It is used by default and is the best choice unless the file system has huge directories and unusual file-name patterns.
;__detect__ : Instructs ''mount'' to detect which hash function is in use by examining the file system being mounted,  and to write this information into the reiserfs superblock. This is only useful on the first mount of an old format file system.

;__hashed_relocation__ : Tunes the block allocator. This may provide performance improvements in some situations.
;__no_unhashed_relocation__ : Tunes the block allocator. This may provide performance improvements in some situations.
;__noborder__ : Disable the border allocator algorithm invented by Yury Yu. Rupasov. This may provide performance improvements in some situations.
;__nolog__ : Disable journalling. This will provide slight performance improvements in some situations at the cost of losing reiserfs's fast recovery from crashes. Even with this option turned on, reiserfs still performs all journalling operations, save for actual writes into its journalling area.  Implementation of ''nolog'' is a work in progress.
;__notail__ : By default, reiserfs stores small files and `file tails' directly into its tree. This confuses some utilities such as lilo(8) __.__ This option is used to disable packing of files into the tree.
;__replayonly__ : Replay the transactions which are in the journal, but do not actually mount the file system. Mainly used by ''reiserfsck'' .
;__resize=__ ''number'' : A remount option which permits online expansion of reiserfs partitions. Instructs reiserfs to assume that the device has ''number'' blocks. This option is designed for use with devices which are under logical volume management (LVM). There is a special ''resizer'' utility which can be obtained from ''ftp://ftp.namesys.com/pub/reiserfsprogs'' .



!!Mount options for romfs
None.



!!Mount options for smbfs
Just like ''nfs'' , the  ''smb'' implementation expects a binary argument (a ''struct smb_mount_data'' ) to the mount system call. This argument is constructed by smbmount(8) and the current version of __mount__ (2.9w) does not know anything about smb.



!!Mount options for sysv
None.



!!Mount options for tmpfs
The following parameters accept a suffix __k__ , __m__ or __g__ for Ki, Mi, Gi (binary kilo, mega and giga) and can be changed on remount.
;__size=__ ''nbytes'' : Override default size of the filesystem. The size is given in bytes, and rounded down to entire pages. The default is half of the memory.
;__nr_blocks=__ : Set number of blocks.
;__nr_inodes=__ : Set number of inodes.
;__mode=__ : Set initial permissions of the root directory.



!!Mount options for udf
udf is the "Universal Disk Format" filesystem defined by the Optical Storage Technology Association, and is often used for DVD-ROM. See also ''iso9660'' .
;__gid=__ : Set the default group.
;__umask=__ : Set the default umask. The value is given in octal.
;__uid=__ : Set the default user.
;__unhide__ : Show otherwise hidden files.
;__undelete__ : Show deleted files in lists.
;__strict__ : Set strict conformance (unused).
;__utf8__ : (unused).
;__iocharset__ : (unused).
;__bs=__ : Set the block size. (May not work unless 2048.)
;__novrs__ : Skip volume sequence recognition.
;__session=__ : Set the CDROM session counting from 0. Default: last session.
;__anchor=__ : Override standard anchor location. Default: 256.
;__volume=__ : Override the !VolumeDesc location. (unused)
;__partition=__ : Override the !PartitionDesc location. (unused)
;__lastblock=__ : Set the last block of the filesystem.
;__fileset=__ : Override the fileset block location. (unused)
;__rootdir=__ : Override the root directory location. (unused)



!!Mount options for ufs

;__ufstype=__ ''value'' : UFS is a file system widely used in different operating systems. The problem are differences among implementations. Features of some implementations are undocumented, so its hard to recognize the type of ufs automatically. That's why the user must specify the type of ufs by mount option. Possible values are:

;__old__ : Old format of ufs, this is the default, read only. (Don't forget to give the -r option.)
;__44bsd__ : For filesystems created by a BSD-like system (NetBSD,FreeBSD,OpenBSD).
;__sun__ : For filesystems created by SunOS or Solaris on Sparc.
;__sunx86__ : For filesystems created by Solaris on x86.
;__nextstep__ : For filesystems created by NeXTStep (on NeXT station) (currently read only).
;__nextstep-cd__ : For !NextStep CDROMs (block_size == 2048), read-only.
;__openstep__ : For filesystems created by !OpenStep (currently read only). The same filesystem type is also used by Mac OS X.


;__onerror=__ ''value'' : Set behaviour on error:

;__panic__ : If an error is encountered, cause a kernel panic.
;__[[lock|umount|repair]__ : These mount options don't do anything at present; when an error is encountered only a console message is printed.




!!Mount options for umsdos
See mount options for msdos. The __dotsOK__ option is explicitly killed by ''umsdos'' .



!!Mount options for vfat
First of all, the mount options for ''fat'' are recognized. The __dotsOK__ option is explicitly killed by ''vfat'' . Furthermore, there are
;__uni_xlate__ : Translate unhandled Unicode characters to special escaped sequences. This lets you backup and restore filenames that are created with any Unicode characters. Without this option, a '?' is used when no translation is possible. The escape character is ':' because it is otherwise illegal on the vfat filesystem. The escape sequence that gets used, where u is the unicode character, is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12).
;__posix__ : Allow two files with names that only differ in case.
;__nonumtail__ : First try to make a short name without sequence number, before trying ''name~num.ext'' .
;__utf8__ : UTF8 is the filesystem safe 8-bit encoding of Unicode that is used by the console. It can be be enabled for the filesystem with this option. If `uni_xlate' gets set, UTF8 gets disabled.
;__shortname=[[lower|win95|winnt|mixed]__ :

Defines the behaviour for creation and display of filenames which fit into 8.3 characters. If a long name for a file exists, it will always be preferred display. There are four modes:

;''lower'' : Force the short name to lower case upon display; store a long name when  the short name is not all upper case.
;''win95'' : Force the short name to upper case upon display; store a long name when the short name is not all upper case. . TP ''winnt'' Display the shortname as is; store a long name when the short name is  not all lower case or all upper case.
;''mixed'' : Display the short name as is; store a long name when the short name is not all upper case.


The default is "lower".



!!Mount options for xenix
None.



!!Mount options for xfs

;__biosize=__ ''size'' : Sets the preferred buffered I/O size (default size is 64K). ''size'' must be expressed as the logarithm (base2) of the desired I/O size. Valid values for this option are 14 through 16, inclusive (i.e. 16K, 32K, and 64K bytes). On machines with a 4K pagesize, 13 (8K bytes) is also a valid ''size'' . The preferred buffered I/O size can also be altered on an individual file basis using the ioctl(2) system call.
;__dmapi " / " xdsm__ : Enable the DMAPI (Data Management API) event callouts.
;__logbufs=__ ''value'' : Set the number of in-memory log buffers. Valid numbers range from 2-8 inclusive. The default value is 8 buffers for filesystems with a blocksize of 64K, 4 buffers for filesystems with a blocksize of 32K, 3 buffers for filesystems with a blocksize of 16K, and 2 buffers for all other configurations. Increasing the number of buffers may increase performance on some workloads at the cost of the memory used for the additional log buffers and their associated control structures.
;__logbsize=__ ''value'' : Set the size of each in-memory log buffer. Valid sizes are 16384 (16K) and 32768 (32K). The default value for machines with more than 32MB of memory is 32768, machines with less memory use 16384 by default.
;__logdev=__''device'' and __rtdev=__''device'' : Use an external log (metadata journal) and/or real-time device. An XFS filesystem has up to three parts: a data section, a log section, and a real-time section. The real-time section is optional, and the log section can be separate from the data section or contained within it. Refer to xfs(5).
;__noalign__ : Data allocations will not be aligned at stripe unit boundaries.
;__noatime__ : Access timestamps are not updated when a file is read.
;__norecovery__ : The filesystem will be mounted without running log recovery. If the filesystem was not cleanly unmounted, it is likely to be inconsistent when mounted in __norecovery__ mode. Some files or directories may not be accessible because of this. Filesystems mounted __norecovery__ must be mounted read-only or the mount will fail.
;__osyncisdsync__ : Make writes to files opened with the O_SYNC flag set behave as if the O_DSYNC flag had been used instead. This can result in better performance without compromising data safety. However if this option is in effect, timestamp updates from O_SYNC writes can be lost if the system crashes.
;__quota__  /  __usrquota__  /  __uqnoenforce__ : User disk quota accounting enabled, and limits (optionally) enforced.
;__grpquota__  /  __gqnoenforce__ : Group disk quota accounting enabled and limits (optionally) enforced.
;__sunit=__''value'' and __swidth=__''value'' : Used to specify the stripe unit and width for a RAID device or a stripe volume. ''value'' must be specified in 512-byte block units. If this option is not specified and the filesystem was made on a stripe volume or the stripe width or unit were specified for the RAID device at mkfs time, then the mount system call will restore the value from the superblock. For filesystems that are made directly on RAID devices, these options can be used to override the information in the superblock if the underlying disk layout changes after the filesystem has been created. The __swidth__ option is required if the __sunit__ option has been specified, and must be a multiple of the __sunit__ value.



!!Mount options for xiafs
None. Although nothing is wrong with xiafs, it is not used much, and is not maintained. Probably one shouldn't use it. Since Linux version 2.1.21 xiafs is no longer part of the kernel source.



!!THE LOOP DEVICE
One further possible type is a mount via the loop device. For example, the command


 __mount /tmp/fdimage /mnt -t msdos -o loop=/dev/loop3,blocksize=1024__



will set up the loop device ''/dev/loop3'' to correspond to the file ''/tmp/fdimage'' , and then mount this device on ''/mnt'' . This type of mount knows about three options, namely __loop__ ,  __offset__  and  __encryption__ , that are really options to losetup(8). If the mount requires a passphrase, you will be prompted for one unless you specify a file descriptor to read from instead with the  __- pass-fd__ option. If no explicit loop device is mentioned (but just an option `__-o loop__' is given), then __mount__ will try to find some unused loop device and use that. If you are not so unwise as to make ''/etc/mtab'' a symbolic link to ''/proc/mounts'' then any loop device allocated by __mount__ will be freed by __umount__ . You can also free a loop device by hand, using `losetup -d', see losetup(8).



!!RETURN CODES
__mount__ has the following return codes (the bits can be ORed):
;__0__ : success
;__1__ : incorrect invocation or permissions
;__2__ : system error (out of memory, cannot fork, no more loop devices)
;__4__ : internal __mount__ bug or missing __nfs__ support in __mount__
;__8__ : user interrupt
;__16__ : problems writing or locking /etc/mtab
;__32__ : mount failure
;__64__ : some mount succeeded




!!FILES
''/etc/fstab'' file system table
''/etc/mtab'' table of mounted file systems
''/etc/mtab~'' lock file
''/etc/mtab.tmp'' temporary file

!!SEE ALSO
mount(2), umount(2), fstab(5), umount(8), swapon(8), nfs(5), xfs(5), e2label(8), xfs_admin(8), mountd(8), nfsd(8), mke2fs(8), tune2fs(8), losetup(8)

!!BUGS
It is possible for a corrupted file system to cause a crash.

Some Linux file systems don't support __-o sync and -o dirsync__ (the ext2 and ext3 file systems ''do'' support synchronous updates (a la BSD) when mounted with the __sync__ option).

The __-o remount__ may not be able to change mount parameters (all ''ext2fs'' -specific parameters, except __sb__ , are changeable with a remount, for example, but you can't change __gid__ or __umask__ for the ''fatfs'' ).

!!HISTORY
A __mount__ command existed in Version 5 AT&T UNIX.
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Last edited on Friday, October 3, 2003 5:13:18 pm by JohnMcPherson
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