Output version.

Print a help message.

Verbose mode.

Mount all filesystems (of the given types) mentioned in fstab.

(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.

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.

Don't call the /sbin/mount.<filesystem> helper even if it exists.

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), or for reiserfs using reiserfstune(8).

Mount without writing in /etc/mtab. This is necessary for example when /etc is on a read-only file system.

In case of a loop mount with encryption, read the passphrase from file descriptor num instead of from the terminal.

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.

Mount the file system read-only. A synonym is −o ro.

Mount the file system read/write. This is the default. A synonym is −o rw.

Mount the partition that has the specified label.

Mount the partition that has the specified uuid. These two options require the file /proc/partitions (present since Linux 2.1.116) to exist.

The argument following the −t is used to indicate the file system type. The file system types which are currently supported include: adfs, affs, autofs, cifs, coda, coherent, cramfs, debugfs, 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, usbfs, 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 — use sysv instead. Since kernel version 2.1.21 the types ext and xiafs do not exist anymore. Earlier, usbfs was known as usbdevfs.

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, cifs, smbfs, ncpfs) ad hoc code is necessary. The nfs ad hoc code is built in, but cifs, 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.smbfs may have to be a shell script that sets up the desired call.

If no −t option is given, or if the auto type is specified, mount will try to guess the desired type. If mount was compiled with the blkid library, the guessing is done by this library. Otherwise, mount guesses itself by probing the superblock; if that does not turn up anything that looks familiar, mount will try to read the file /etc/filesystems, or, if that does not exist, /proc/filesystems. All of the filesystem types listed there will be tried, except for those that are labeled "nodev" (e.g., devpts, proc and nfs). If /etc/filesystems ends in a line with a single * 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 ext3 before ext2) 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:

mounts all file systems except those of type msdos and ext.

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:

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

mounts all ext2 filesystems with the _netdev option, not all filesystems that are either ext2 or have the _netdev option specified.

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, fat, vfat and ufs):

Remount a subtree somewhere else (so that its contents are available in both places). See above.

Move a subtree to some other place. See above.

Set the owner and group of the files in the file system (default: uid=gid=0).

Set the permission mask for ADFS 'owner' permissions and 'other' permissions, respectively (default: 0700 and 0077, respectively). See also /usr/src/linux/Documentation/filesystems/adfs.txt.

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).

Set the owner and group of all files.

Set the mode of all files to value & 0777 disregarding the original permissions. Add search permission to directories that have read permission. The value is given in octal.

Do not allow any changes to the protection bits on the file system.

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...

Print an informational message for each successful mount.

Prefix used before volume name, when following a link.

Prefix (of length at most 30) used before '/' when following a symbolic link.

(Default: 2.) Number of unused blocks at the start of the device.

Give explicitly the location of the root block.

Give blocksize. Allowed values are 512, 1024, 2048, 4096.

These options are accepted but ignored. (However, quota utilities may react to such strings in /etc/fstab.)

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.

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.

Support POSIX Access Control Lists (or not).

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.)

No checking is done at mount time. This is the default. This is fast. It is wise to invoke e2fsck(8) every now and then, e.g. at boot time.

Print debugging info upon each (re)mount.

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).

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.

These options are accepted but ignored.

Do not attach buffer_heads to file pagecache. (Since 2.5.49.)

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

Use old allocator or Orlov allocator for new inodes. Orlov is default.

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.)

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 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".

Support "user." extended attributes (or not).

Update the ext3 file system's journal to the current format.

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.

Do not load the ext3 file system's journal on mounting.

Specifies the journalling mode for file data. Metadata is always journaled. To use modes other than ordered on the root file system, pass the mode to the kernel as boot parameter, e.g. rootflags=data=journal.

Sync all data and metadata every nrsec seconds. The default value is 5 seconds. Zero means default.

Set blocksize (default 512).

Set the owner and group of all files. (Default: the uid and gid of the current process.)

Set the umask (the bitmask of the permissions that are not present). The default is the umask of the current process. The value is given in octal.

Set the umask applied to directories only. The default is the umask of the current process. The value is given in octal.

Set the umask applied to regular files only. The default is the umask of the current process. The value is given in octal.

Three different levels of pickyness can be chosen:

Sets the codepage for converting to shortname characters on FAT and VFAT filesystems. By default, codepage 437 is used.

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:

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.

Option passed to the CVF module.

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).

Specify a 12, 16 or 32 bit fat. This overrides the automatic FAT type detection routine. Use with caution!

Character set to use for converting between 8 bit characters and 16 bit Unicode characters. The default is iso8859-1. Long filenames are stored on disk in Unicode format.

Turn on the quiet flag. Attempts to chown or chmod files do not return errors, although they fail. Use with caution!

Various misguided attempts to force Unix or DOS conventions onto a FAT file system.

Set the creator/type values as shown by the MacOS finder used for creating new files. Default values: '????'.

Set the owner and group of all files. (Default: the uid and gid of the current process.)

Set the umask used for all directories, all regular files, or all files and directories. Defaults to the umask of the current process.

Select the CDROM session to mount. Defaults to leaving that decision to the CDROM driver. This option will fail with anything but a CDROM as underlying device.

Select partition number n from the device. Only makes sense for CDROMS. Defaults to not parsing the partition table at all.

Don't complain about invalid mount options.

Set the owner and group of all files. (Default: the uid and gid of the current process.)

Set the umask (the bitmask of the permissions that are not present). The default is the umask of the current process. The value is given in octal.

Convert all files names to lower case, or leave them. (Default: case=lower.)

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.

Do not abort mounting when certain consistency checks fail.

Disable the use of Rock Ridge extensions, even if available. Cf. map.

Disable the use of Microsoft Joliet extensions, even if available. Cf. map.

With check=relaxed, a filename is first converted to lower case before doing the lookup. This is probably only meaningful together with norock and map=normal. (Default: check=strict.)

Give all files in the file system the indicated user or group id, possibly overriding the information found in the Rock Ridge extensions. (Default: uid=0,gid=0.)

For non-Rock Ridge volumes, normal name translation maps upper to lower case ASCII, drops a trailing `;1', and converts `;' to `.'. With map=off no name translation is done. See norock. (Default: map=normal.) map=acorn is like map=normal but also apply Acorn extensions if present.

For non-Rock Ridge volumes, give all files the indicated mode. (Default: read 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.)

Also show hidden and associated files. (If the ordinary files and the associated or hidden files have the same filenames, this may make the ordinary files inaccessible.)

Set the block size to the indicated value. (Default: block=1024.)

(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.)

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.

Select number of session on multisession CD. (Since 2.3.4.)

Session begins from sector xxx. (Since 2.3.4.)

Character set to use for converting 16 bit Unicode characters on CD to 8 bit characters. The default is iso8859-1.

Convert 16 bit Unicode characters on CD to UTF-8.

Character set to use for converting from Unicode to ASCII. The default is to do no conversion. Use iocharset=utf8 for UTF8 translations. This requires CONFIG_NLS_UTF8 to be set in the kernel .config file.

Resize the volume to value blocks. JFS only supports growing a volume, not shrinking it. This option is only valid during a remount, when the volume is mounted read-write. The resize keyword with no value will grow the volume to the full size of the partition.

Do not write to the journal. The primary use of this option is to allow for higher performance when restoring a volume from backup media. The integrity of the volume is not guaranteed if the system abnormally abends.

Default. Commit metadata changes to the journal. Use this option to remount a volume where the nointegrity option was previously specified in order to restore normal behavior.

Define the 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.)

These options are accepted but ignored.

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.)

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.

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.

Do not use locking. Do not start lockd.

Character set to use when returning file names. Unlike VFAT, NTFS suppresses names that contain unconvertible characters. Deprecated.

New name for the option earlier called iocharset.

Use UTF-8 for converting file names.

For 0 (or `no' or `false'), do not use escape sequences for unknown Unicode characters. For 1 (or `yes' or `true') or 2, use vfat-style 4-byte escape sequences starting with ":". Here 2 give a little-endian encoding and 1 a byteswapped bigendian encoding.

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.

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.

These options are recognized, but have no effect as far as I can see.

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.

Choose which hash function reiserfs will use to find files within directories.

Tunes the block allocator. This may provide performance improvements in some situations.

Tunes the block allocator. This may provide performance improvements in some situations.

Disable the border allocator algorithm invented by Yury Yu. Rupasov. This may provide performance improvements in some situations.

Disable 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.

By default, reiserfs stores small files and `file tails' directly into its tree. This confuses some utilities such as LILO(8). This option is used to disable packing of files into the tree.

Replay the transactions which are in the journal, but do not actually mount the file system. Mainly used by reiserfsck.

A remount option which permits online expansion of reiserfs partitions. Instructs reiserfs to assume that the device has number blocks. This option is designed for use with devices which are under logical volume management (LVM). There is a special resizer utility which can be obtained from ftp://ftp.namesys.com/pub/reiserfsprogs.

Override default maximum size of the filesystem. The size is given in bytes, and rounded down to entire pages. The default is half of the memory.

Set number of blocks.

Set number of inodes.

Set initial permissions of the root directory.

Set the default group.

Set the default umask. The value is given in octal.

Set the default user.

Show otherwise hidden files.

Show deleted files in lists.

Unset strict conformance.

Set the NLS character set.

Set the block size. (May not work unless 2048.)

Skip volume sequence recognition.

Set the CDROM session counting from 0. Default: last session.

Override standard anchor location. Default: 256.

Override the VolumeDesc location. (unused)

Override the PartitionDesc location. (unused)

Set the last block of the filesystem.

Override the fileset block location. (unused)

Override the root directory location. (unused)

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:

Set behaviour on error:

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).

Allow two files with names that only differ in case.

First try to make a short name without sequence number, before trying name~num.ext.

UTF8 is the filesystem safe 8-bit encoding of Unicode that is used by the console. It can be be enabled for the filesystem with this option. If `uni_xlate' gets set, UTF8 gets disabled.

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:

The default is "lower".

Set the owner and group and mode of the device files in the usbfs file system (default: uid=gid=0, mode=0644). The mode is given in octal.

Set the owner and group and mode of the bus directories in the usbfs file system (default: uid=gid=0, mode=0555). The mode is given in octal.

Set the owner and group and mode of the file devices (default: uid=gid=0, mode=0444). The mode is given in octal.

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.

Enable the DMAPI (Data Management API) event callouts.

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.

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.

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).

Data allocations will not be aligned at stripe unit boundaries.

Access timestamps are not updated when a file is read.

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.

Ignore the filesystem uuid. This avoids errors for duplicate uuids.

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.

User disk quota accounting enabled, and limits (optionally) enforced.

Group disk quota accounting enabled and limits (optionally) enforced.

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.

success

incorrect invocation or permissions

system error (out of memory, cannot fork, no more loop devices)

internal mount bug or missing nfs support in mount

user interrupt

problems writing or locking /etc/mtab

mount failure

some mount succeeded

file system table

table of mounted file systems

lock file

temporary file

a list of filesystem types to try