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| .TH MOUNT 8 "July 2014" "util-linux" "System Administration" |
| .SH NAME |
| mount \- mount a filesystem |
| .SH SYNOPSIS |
| .B mount |
| .RB [ \-lhV ] |
| .LP |
| .\" Quote used to include space between arguments |
| .B "mount \-a |
| .RB [ \-fFnrsvw ] |
| .RB [ \-t |
| .IR vfstype ] |
| .RB [ \-O |
| .IR optlist ] |
| .LP |
| .B mount |
| .RB [ \-fnrsvw ] |
| .RB [ \-o |
| .IR option [ \fB,\fIoption ]...] |
| .IR device | dir |
| .LP |
| .B mount |
| .RB [ \-fnrsvw ] |
| .RB [ \-t |
| .IB vfstype ] |
| .RB [ \-o |
| .IR options ] |
| .I device dir |
| .SH DESCRIPTION |
| All files accessible in a Unix system are arranged in one big |
| tree, the file hierarchy, rooted at |
| .BR / . |
| These files can be spread out over several devices. The |
| .B mount |
| command serves to attach the filesystem found on some device |
| to the big file tree. Conversely, the |
| .BR umount (8) |
| command will detach it again. |
| |
| The standard form of the |
| .B mount |
| command is: |
| .RS |
| |
| .br |
| .BI "mount \-t" " type device dir" |
| .br |
| |
| .RE |
| This tells the kernel to attach the filesystem found on |
| .I device |
| (which is of type |
| .IR type ) |
| at the directory |
| .IR dir . |
| The previous contents (if any) and owner and mode of |
| .I dir |
| become invisible, and as long as this filesystem remains mounted, |
| the pathname |
| .I dir |
| refers to the root of the filesystem on |
| .IR device . |
| |
| If only the directory or the device is given, for example: |
| .RS |
| |
| .br |
| .BI "mount /dir" |
| .br |
| |
| .RE |
| then \fBmount\fR looks for a mountpoint (and if not found then for a device) in the |
| .IR /etc/fstab |
| file. It's possible to use the |
| .B \-\-target |
| or |
| .B \-\-source |
| options to avoid ambivalent interpretation of the given argument. For example: |
| .RS |
| |
| .br |
| .BI "mount \-\-target /mountpoint" |
| .br |
| |
| .RE |
| |
| |
| .B The listing. |
| .RS |
| The listing mode is maintained for backward compatibility only. |
| |
| For more robust and customizable output use |
| .BR findmnt (8), |
| \fBespecially in your scripts\fP. Note that control characters in the |
| mountpoint name are replaced with '?'. |
| |
| The following command lists all mounted filesystems (of type |
| .IR type ): |
| |
| .RS |
| .br |
| .BR "mount " [ \-l "] [" "\-t \fItype\/\fP" ] |
| .br |
| .RE |
| |
| The option \fB\-l\fR adds labels to this listing. See below. |
| .RE |
| |
| .B The device indication. |
| .RS |
| Most devices are indicated by a filename (of a block special device), like |
| .IR /dev/sda1 , |
| but there are other possibilities. For example, in the case of an NFS mount, |
| .I device |
| may look like |
| .IR knuth.cwi.nl:/dir . |
| It is also possible to indicate a block special device using its filesystem label |
| or UUID (see the \fB\-L\fR and \fB\-U\fR options below), or its partition label |
| or UUID. (Partition identifiers are supported for example for GUID Partition |
| Tables (GPT).) |
| |
| Don't forget that there is no guarantee that UUIDs and labels are really |
| unique, especially if you move, share or copy the device. Use |
| .B "lsblk \-o +UUID,PARTUUID" |
| to verify that the UUIDs are really unique in your system. |
| |
| The recommended setup is to use tags (e.g. \fBLABEL=\fIlabel\fR) rather than |
| .B /dev/disk/by-{label,uuid,partuuid,partlabel} |
| udev symlinks in the /etc/fstab file. Tags are |
| more readable, robust and portable. The |
| .BR mount (8) |
| command internally uses udev |
| symlinks, so the use of symlinks in /etc/fstab has no advantage over tags. |
| For more details see |
| .BR libblkid (3). |
| |
| Note that |
| .BR mount (8) |
| uses UUIDs as strings. The UUIDs from the command line or from |
| .BR fstab (5) |
| are not converted to internal binary representation. The string representation |
| of the UUID should be based on lower case characters. |
| |
| The |
| .I proc |
| filesystem is not associated with a special device, and when |
| mounting it, an arbitrary keyword, such as |
| .I proc |
| can be used instead of a device specification. |
| (The customary choice |
| .I none |
| is less fortunate: the error message `none busy' from |
| .B umount |
| can be confusing.) |
| .RE |
| |
| .B The /etc/fstab, /etc/mtab and /proc/mounts files. |
| .RS |
| The file |
| .I /etc/fstab |
| (see |
| .BR fstab (5)), |
| may contain lines describing what devices are usually |
| mounted where, using which options. The default location of the |
| .BR fstab (5) |
| file can be overridden with the |
| .BI \-\-fstab " path" |
| command-line option (see below for more details). |
| .LP |
| The command |
| .RS |
| .sp |
| .B mount \-a |
| .RB [ \-t |
| .IR type ] |
| .RB [ \-O |
| .IR optlist ] |
| .sp |
| .RE |
| (usually given in a bootscript) causes all filesystems mentioned in |
| .I 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 |
| .B noauto |
| keyword. Adding the |
| .B \-F |
| option will make mount fork, so that the |
| filesystems are mounted simultaneously. |
| .LP |
| When mounting a filesystem mentioned in |
| .I fstab |
| or |
| .IR mtab , |
| it suffices to specify on the command line only the device, or only the mount point. |
| |
| |
| The programs |
| .B mount |
| and |
| .B umount |
| traditionally maintained list of currently mounted filesystems in the file |
| .IR /etc/mtab . |
| The mtab file is still supported, but it's recommended to use a symlink to |
| the file |
| .I /proc/mounts |
| rather than the regular mtab file on the current Linux systems. |
| The mtab file maintained in userspace cannot reliably work with namespaces, containers |
| and another advanced Linux features. |
| |
| If no arguments are given to |
| .BR mount , |
| this list is printed. |
| |
| If you want to override mount options from |
| .I /etc/fstab |
| you have to use the \fB\-o\fR option: |
| .RS |
| .sp |
| .BI mount " device" \fR| "dir " \-o " options" |
| .sp |
| .RE |
| and then the mount options from the command line will be appended to |
| the list of options from |
| .IR /etc/fstab . |
| The usual behavior is that the last option wins if there are conflicting |
| ones. |
| |
| The |
| .B mount |
| program does not read the |
| .I /etc/fstab |
| file if both |
| .I device |
| (or LABEL, UUID, PARTUUID or PARTLABEL) and |
| .I dir |
| are specified. For example, to mount device |
| .BR foo " at " /dir : |
| .RS |
| .sp |
| .B "mount /dev/foo /dir" |
| .sp |
| .RE |
| .RE |
| |
| .B The non-superuser mounts. |
| .RS |
| Normally, only the superuser can mount filesystems. |
| However, when |
| .I fstab |
| contains the |
| .B user |
| option on a line, anybody can mount the corresponding filesystem. |
| .LP |
| Thus, given a line |
| .RS |
| .sp |
| .B "/dev/cdrom /cd iso9660 ro,user,noauto,unhide" |
| .sp |
| .RE |
| any user can mount the iso9660 filesystem found on an inserted CDROM |
| using the command |
| .RS |
| .sp |
| .B "mount /dev/cdrom" |
| .sp |
| .RE |
| or |
| .RS |
| .sp |
| .B "mount /cd" |
| .sp |
| .RE |
| For more details, see |
| .BR fstab (5). |
| Only the user that mounted a filesystem can unmount it again. |
| If any user should be able to unmount it, then use |
| .B users |
| instead of |
| .B user |
| in the |
| .I fstab |
| line. |
| The |
| .B owner |
| option is similar to the |
| .B user |
| option, with the restriction that the user must be the owner |
| of the special file. This may be useful e.g.\& for |
| .I /dev/fd |
| if a login script makes the console user owner of this device. |
| The |
| .B group |
| option is similar, with the restriction that the user must be |
| member of the group of the special file. |
| .RE |
| |
| .B The bind mounts. |
| .RS |
| .\" In fact since 2.3.99. At first the syntax was mount -t bind. |
| Since Linux 2.4.0 it is possible to remount part of the |
| file hierarchy somewhere else. The call is: |
| |
| .RS |
| .br |
| .B mount \-\-bind |
| .I olddir newdir |
| .RE |
| |
| or by using this fstab entry: |
| |
| .RS |
| .br |
| .BI / olddir |
| .BI / newdir |
| .B none bind |
| .RE |
| |
| After this call the same contents are accessible in two places. |
| One can also remount a single file (on a single file). It's also |
| possible to use the bind mount to create a mountpoint from a regular |
| directory, for example: |
| |
| .RS |
| .br |
| .B mount \-\-bind foo foo |
| .RE |
| |
| The bind mount call attaches only (part of) a single filesystem, not possible |
| submounts. The entire file hierarchy including submounts is attached |
| a second place by using: |
| |
| .RS |
| .br |
| .B mount \-\-rbind |
| .I olddir newdir |
| .RE |
| |
| Note that the filesystem mount options will remain the same as those |
| on the original mount point, and cannot be changed by passing the |
| .B \-o |
| option along with |
| .BR \-\-bind / \-\-rbind . |
| The mount options can be |
| changed by a separate remount command, for example: |
| |
| .RS |
| .br |
| .B mount \-\-bind |
| .I olddir newdir |
| .br |
| .B mount \-o remount,ro |
| .I newdir |
| .RE |
| |
| Note that the behavior of the remount operation depends on the /etc/mtab file. |
| The first command stores the 'bind' flag in the /etc/mtab file and the second |
| command reads the flag from the file. If you have a system without the |
| /etc/mtab file or if you explicitly define source and target for the remount |
| command (then \fBmount\fR(8) does not read /etc/mtab), then you have to use |
| the bind flag (or option) for the remount command too. For example: |
| |
| .RS |
| .br |
| .B mount \-\-bind |
| .I olddir newdir |
| .br |
| .B mount \-o remount,ro,bind |
| .I olddir newdir |
| .RE |
| |
| Note that |
| .B remount,ro,bind |
| will create a read-only mountpoint (VFS entry), but the original filesystem |
| superblock will still be writable, meaning that the |
| .I olddir |
| will be writable, but the |
| .I newdir |
| will be read-only. |
| .RE |
| |
| .B The move operation. |
| .RS |
| Since Linux 2.5.1 it is possible to atomically move a |
| .B mounted tree |
| to another place. The call is: |
| |
| .RS |
| .br |
| .B mount \-\-move |
| .I olddir newdir |
| .RE |
| |
| This will cause the contents which previously appeared under |
| .I olddir |
| to now be accessible under |
| .IR newdir . |
| The physical location of the files is not changed. |
| Note that |
| .I olddir |
| has to be a mountpoint. |
| |
| Note also that moving a mount residing under a shared mount is invalid and |
| unsupported. Use |
| .B findmnt \-o TARGET,PROPAGATION /dir |
| to see the current propagation flags. |
| .RE |
| |
| .B The shared subtree operations. |
| .RS |
| Since Linux 2.6.15 it is possible to mark a mount and its submounts as shared, |
| private, slave or unbindable. A shared mount provides the ability to create mirrors |
| of that mount such that mounts and unmounts within any of the mirrors propagate |
| to the other mirror. A slave mount receives propagation from its master, but |
| not vice versa. A private mount carries no propagation abilities. An |
| unbindable mount is a private mount which cannot be cloned through a bind |
| operation. The detailed semantics are documented in |
| .B Documentation/filesystems/sharedsubtree.txt |
| file in the kernel source tree. |
| |
| Supported operations are: |
| |
| .RS |
| .nf |
| .BI "mount \-\-make-shared " mountpoint |
| .BI "mount \-\-make-slave " mountpoint |
| .BI "mount \-\-make-private " mountpoint |
| .BI "mount \-\-make-unbindable " mountpoint |
| .fi |
| .RE |
| |
| The following commands allow one to recursively change the type of all the |
| mounts under a given mountpoint. |
| |
| .RS |
| .nf |
| .BI "mount \-\-make-rshared " mountpoint |
| .BI "mount \-\-make-rslave " mountpoint |
| .BI "mount \-\-make-rprivate " mountpoint |
| .BI "mount \-\-make-runbindable " mountpoint |
| .fi |
| .RE |
| |
| .BR mount (8) |
| .B does not read |
| .BR fstab (5) |
| when a \fB\-\-make-\fR* operation is requested. All necessary information has to be |
| specified on the command line. |
| |
| Note that the Linux kernel does not allow to change multiple propagation flags |
| with a single |
| .BR mount (2) |
| syscall, and the flags cannot be mixed with other mount options. |
| |
| Since util-linux 2.23 the \fBmount\fR command allows to use several propagation flags |
| together and also together with other mount operations. This feature is EXPERIMENTAL. |
| The propagation flags are applied by additional \fBmount\fR(2) syscalls when the |
| preceeding mount operations were successful. Note that this use case is not |
| atomic. It is possible to specify the propagation flags in |
| .BR fstab (5) |
| as mount options |
| .RB ( private , |
| .BR slave , |
| .BR shared , |
| .BR unbindable , |
| .BR rprivate , |
| .BR rslave , |
| .BR rshared , |
| .BR runbindable ). |
| |
| For example: |
| |
| .RS |
| .nf |
| .BI "mount \-\-make-private \-\-make-unbindable /dev/sda1 /foo" |
| .fi |
| .RE |
| |
| is the same as: |
| |
| .RS |
| .nf |
| .BI "mount /dev/sda1 /foo" |
| .BI "mount \-\-make-private /foo" |
| .BI "mount \-\-make-unbindable /foo" |
| .fi |
| .RE |
| .RE |
| |
| .SH COMMAND-LINE OPTIONS |
| The full set of mount options used by an invocation of |
| .B mount |
| is determined by first extracting the |
| mount options for the filesystem from the |
| .I fstab |
| table, then applying any options specified by the |
| .B \-o |
| argument, and finally applying a |
| .BR \-r " or " \-w |
| option, when present. |
| |
| The command \fBmount\fR does not pass all command-line options to the |
| \fB/sbin/mount.\fIsuffix\fR mount helpers. The interface between \fBmount\fR |
| and the mount helpers is described below in the section EXTERNAL HELPERS. |
| |
| Command-line options available for the |
| .B mount |
| command are: |
| .IP "\fB\-V, \-\-version\fP" |
| Display version information and exit. |
| .IP "\fB\-h, \-\-help\fP" |
| Display help text and exit. |
| .IP "\fB\-v, \-\-verbose\fP" |
| Verbose mode. |
| .IP "\fB\-a, \-\-all\fP" |
| Mount all filesystems (of the given types) mentioned in |
| .I fstab |
| (except for those whose line contains the |
| .B noauto |
| keyword). The filesystems are mounted following their order in |
| .IR fstab . |
| .IP "\fB\-F, \-\-fork\fP" |
| (Used in conjunction with |
| .BR \-a .) |
| Fork off a new incarnation of \fBmount\fR 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 |
| .I /usr |
| and |
| .IR /usr/spool . |
| .IP "\fB\-f, \-\-fake\fP" |
| Causes everything to be done except for the actual system call; if it's not |
| obvious, this ``fakes'' mounting the filesystem. This option is useful in |
| conjunction with the |
| .B \-v |
| flag to determine what the |
| .B mount |
| command is trying to do. It can also be used to add entries for devices |
| that were mounted earlier with the \fB\-n\fR option. The \fB\-f\fR option |
| checks for an existing record in /etc/mtab and fails when the record already |
| exists (with a regular non-fake mount, this check is done by the kernel). |
| .IP "\fB\-i, \-\-internal-only\fP" |
| Don't call the \fB/sbin/mount.\fIfilesystem\fR helper even if it exists. |
| .IP "\fB\-l, \-\-show-labels\fP" |
| Add the labels in the mount output. \fBmount\fR 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, ext3 or ext4 using the |
| .BR e2label (8) |
| utility, or for XFS using |
| .BR xfs_admin (8), |
| or for reiserfs using |
| .BR reiserfstune (8). |
| .IP "\fB\-n, \-\-no-mtab\fP" |
| Mount without writing in |
| .IR /etc/mtab . |
| This is necessary for example when |
| .I /etc |
| is on a read-only filesystem. |
| .IP "\fB\-c, \-\-no-canonicalize\fP" |
| Don't canonicalize paths. The mount command canonicalizes all paths |
| (from command line or fstab) by default. This option can be used |
| together with the |
| .B \-f |
| flag for already canonicalized absolute paths. The option is designed for mount |
| helpers which call \fBmount -i\fR. It is strongly recommended to not use this |
| command-line option for normal mount operations. |
| |
| Note that \fBmount\fR(8) does not pass this option to the |
| \fB/sbin/mount.\fItype\fR helpers. |
| .IP "\fB\-s\fP" |
| Tolerate sloppy mount options rather than failing. This will ignore mount |
| options not supported by a filesystem type. Not all filesystems support this |
| option. Currently it's supported by the \fBmount.nfs\fR mount helper only. |
| .IP "\fB\-\-source \fIdev\fP" |
| If only one argument for the mount command is given then the argument might be |
| interpreted as target (mountpoint) or source (device). This option allows to |
| explicitly define that the argument is the mount source. |
| .IP "\fB\-\-target \fIdir\fP" |
| If only one argument for the mount command is given then the argument might be |
| interpreted as target (mountpoint) or source (device). This option allows to |
| explicitly define that the argument is the mount target. |
| .IP "\fB\-r, \-\-read-only\fP" |
| Mount the filesystem read-only. A synonym is |
| .BR "\-o ro" . |
| |
| Note that, depending on the filesystem type, state and kernel behavior, the |
| system may still write to the device. For example, ext3 and ext4 will replay the |
| journal if the filesystem is dirty. To prevent this kind of write access, you |
| may want to mount an ext3 or ext4 filesystem with the \fBro,noload\fR mount |
| options or set the block device itself to read-only mode, see the |
| .BR blockdev (8) |
| command. |
| .IP "\fB\-w, \-\-rw, \-\-read-write\fP" |
| Mount the filesystem read/write. This is the default. A synonym is |
| .BR "\-o rw" . |
| .IP "\fB\-L, \-\-label \fIlabel\fP" |
| Mount the partition that has the specified |
| .IR label . |
| .IP "\fB\-U, \-\-uuid \fIuuid\fP" |
| Mount the partition that has the specified |
| .IR uuid . |
| These two options require the file |
| .I /proc/partitions |
| (present since Linux 2.1.116) to exist. |
| .IP "\fB\-T, \-\-fstab \fIpath\fP" |
| Specifies an alternative fstab file. If \fIpath\fP is a directory then the files |
| in the directory are sorted by |
| .BR strverscmp (3); |
| files that start with "."\& or without an \&.fstab extension are ignored. The option |
| can be specified more than once. This option is mostly designed for initramfs |
| or chroot scripts where additional configuration is specified beyond standard |
| system configuration. |
| |
| Note that \fBmount\fR(8) does not pass the option \fB\-\-fstab\fP to the |
| \fB/sbin/mount.\fItype\fR helpers, meaning that the alternative fstab files will be |
| invisible for the helpers. This is no problem for normal mounts, but user |
| (non-root) mounts always require fstab to verify the user's rights. |
| .IP "\fB\-t, \-\-types \fIvfstype\fP" |
| The argument following the |
| .B \-t |
| is used to indicate the filesystem type. The filesystem types which are |
| currently supported include: |
| .IR adfs , |
| .IR affs , |
| .IR autofs , |
| .IR btrfs , |
| .IR cifs , |
| .IR coda , |
| .IR coherent , |
| .IR cramfs , |
| .IR debugfs , |
| .IR devpts , |
| .IR efs , |
| .IR ext , |
| .IR ext2 , |
| .IR ext3 , |
| .IR ext4 , |
| .IR hfs , |
| .IR hfsplus , |
| .IR hpfs , |
| .IR iso9660 , |
| .IR jfs , |
| .IR minix , |
| .IR msdos , |
| .IR ncpfs , |
| .IR nfs , |
| .IR nfs4 , |
| .IR ntfs , |
| .IR proc , |
| .IR qnx4 , |
| .IR ramfs , |
| .IR reiserfs , |
| .IR romfs , |
| .IR squashfs , |
| .IR smbfs , |
| .IR sysv , |
| .IR tmpfs , |
| .IR ubifs , |
| .IR udf , |
| .IR ufs , |
| .IR umsdos , |
| .IR usbfs , |
| .IR vfat , |
| .IR xenix , |
| .IR xfs , |
| .IR xiafs . |
| Note that coherent, sysv and xenix are equivalent and that |
| .I xenix |
| and |
| .I coherent |
| will be removed at some point in the future \(en use |
| .I sysv |
| instead. Since kernel version 2.1.21 the types |
| .I ext |
| and |
| .I xiafs |
| do not exist anymore. Earlier, |
| .I usbfs |
| was known as |
| .IR usbdevfs . |
| Note, the real list of all supported filesystems depends on your |
| kernel. |
| |
| The programs |
| .B mount |
| and |
| .B umount |
| support filesystem subtypes. The subtype is defined by a '.subtype' suffix. For |
| example 'fuse.sshfs'. It's recommended to use subtype notation rather than add |
| any prefix to the mount source (for example 'sshfs#example.com' is |
| deprecated). |
| |
| For most types all the |
| .B mount |
| program has to do is issue a simple |
| .IR mount (2) |
| system call, and no detailed knowledge of the filesystem type is required. |
| For a few types however (like nfs, nfs4, cifs, smbfs, ncpfs) an ad hoc code is |
| necessary. The nfs, nfs4, cifs, smbfs, and ncpfs filesystems |
| have a separate mount program. In order to make it possible to |
| treat all types in a uniform way, \fBmount\fR will execute the program |
| .BI /sbin/mount. type |
| (if that exists) when called with type |
| .IR type . |
| Since different versions of the |
| .B smbmount |
| program have different calling conventions, |
| .B /sbin/mount.smbfs |
| may have to be a shell script that sets up the desired call. |
| |
| If no |
| .B \-t |
| option is given, or if the |
| .B auto |
| type is specified, mount will try to guess the desired type. |
| Mount uses the blkid library for guessing the filesystem |
| type; if that does not turn up anything that looks familiar, |
| mount will try to read the file |
| .IR /etc/filesystems , |
| or, if that does not exist, |
| .IR /proc/filesystems . |
| All of the filesystem types listed there will be tried, |
| except for those that are labeled "nodev" (e.g., |
| .IR devpts , |
| .I proc |
| and |
| .IR nfs ). |
| If |
| .I /etc/filesystems |
| ends in a line with a single *, mount will read |
| .I /proc/filesystems |
| afterwards. While trying, all filesystem types will be |
| mounted with the mount option \fBsilent\fR. |
| |
| The |
| .B auto |
| type may be useful for user-mounted floppies. |
| Creating a file |
| .I /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. |
| |
| More than one type may be specified in a comma-separated |
| list. The list of filesystem types can be prefixed with |
| .B no |
| to specify the filesystem types on which no action should be taken. |
| (This can be meaningful with the |
| .B \-a |
| option.) For example, the command |
| .RS |
| .RS |
| .sp |
| .B "mount \-a \-t nomsdos,ext" |
| .sp |
| .RE |
| mounts all filesystems except those of type |
| .I msdos |
| and |
| .IR ext . |
| .RE |
| .IP "\fB\-O, \-\-test-opts \fIopts\fP" |
| Limit the set of filesystems to which the |
| .B \-a |
| option applies. In this regard it is like the |
| .B \-t |
| option except that |
| .B \-O |
| is useless without |
| .BR \-a . |
| For example, the command: |
| .RS |
| .RS |
| .sp |
| .B "mount \-a \-O no_netdev" |
| .sp |
| .RE |
| mounts all filesystems except those which have the option |
| .I _netdev |
| specified in the options field in the |
| .I /etc/fstab |
| file. |
| |
| It is different from |
| .B \-t |
| in that each option is matched exactly; a leading |
| .B no |
| at the beginning of one option does not negate the rest. |
| |
| The |
| .B \-t |
| and |
| .B \-O |
| options are cumulative in effect; that is, the command |
| .RS |
| .sp |
| .B "mount \-a \-t ext2 \-O _netdev" |
| .sp |
| .RE |
| mounts all ext2 filesystems with the _netdev option, not all filesystems |
| that are either ext2 or have the _netdev option specified. |
| .RE |
| .IP "\fB\-o, \-\-options \fIopts\fP" |
| Use the specified mount options. The \fIopts\fR argument is |
| a comma-separated list. For example: |
| .RS |
| .RS |
| .sp |
| .B "mount LABEL=mydisk \-o noatime,nodev,nosuid" |
| .sp |
| .RE |
| |
| For more details, see the |
| .B FILESYSTEM-INDEPENDENT MOUNT OPTIONS |
| and |
| .B FILESYSTEM-SPECIFIC MOUNT OPTIONS |
| sections. |
| .RE |
| .IP "\fB\-B, \-\-bind\fP" |
| Remount a subtree somewhere else (so that its contents are available |
| in both places). See above. |
| .IP "\fB\-R, \-\-rbind\fP" |
| Remount a subtree and all possible submounts somewhere else (so that its |
| contents are available in both places). See above. |
| .IP "\fB\-M, \-\-move\fP" |
| Move a subtree to some other place. See above. |
| |
| .SH FILESYSTEM-INDEPENDENT MOUNT OPTIONS |
| Some of these options are only useful when they appear in the |
| .I /etc/fstab |
| file. |
| |
| Some of these options could be enabled or disabled by default |
| in the system kernel. To check the current setting see the options |
| in /proc/mounts. Note that filesystems also have per-filesystem |
| specific default mount options (see for example \fBtune2fs \-l\fP |
| output for extN filesystems). |
| |
| The following options apply to any filesystem that is being |
| mounted (but not every filesystem actually honors them \(en e.g.\&, the |
| .B sync |
| option today has an effect only for ext2, ext3, fat, vfat and ufs): |
| |
| .TP |
| .B async |
| All I/O to the filesystem should be done asynchronously. (See also the |
| .B sync |
| option.) |
| .TP |
| .B atime |
| Do not use the noatime feature, so the inode access time is controlled by kernel |
| defaults. See also the descriptions of the |
| .B strictatime |
| and |
| .B relatime |
| mount options. |
| .TP |
| .B noatime |
| Do not update inode access times on this filesystem (e.g., for faster |
| access on the news spool to speed up news servers). |
| .TP |
| .B auto |
| Can be mounted with the |
| .B \-a |
| option. |
| .TP |
| .B noauto |
| Can only be mounted explicitly (i.e., the |
| .B \-a |
| option will not cause the filesystem to be mounted). |
| .TP |
| \fBcontext=\fP\,\fIcontext\fP, \fBfscontext=\fP\,/\fIcontext\fP, \fBdefcontext=\fP\,/\fIcontext\fP and \fBrootcontext=\fP\,\fIcontext\fP |
| The |
| .B context= |
| option is useful when mounting filesystems that do not support |
| extended attributes, such as a floppy or hard disk formatted with VFAT, or |
| systems that are not normally running under SELinux, such as an ext3 formatted |
| disk from a non-SELinux workstation. You can also use |
| .B context= |
| on filesystems you do not trust, such as a floppy. It also helps in compatibility with |
| xattr-supporting filesystems on earlier 2.4.<x> kernel versions. Even where |
| xattrs are supported, you can save time not having to label every file by |
| assigning the entire disk one security context. |
| |
| A commonly used option for removable media is |
| .BR context="system_u:object_r:removable_t" . |
| |
| Two other options are |
| .B fscontext= |
| and |
| .BR defcontext= , |
| both of which are mutually exclusive of the context option. This means you |
| can use fscontext and defcontext with each other, but neither can be used with |
| context. |
| |
| The |
| .B fscontext= |
| option works for all filesystems, regardless of their xattr |
| support. The fscontext option sets the overarching filesystem label to a |
| specific security context. This filesystem label is separate from the |
| individual labels on the files. It represents the entire filesystem for |
| certain kinds of permission checks, such as during mount or file creation. |
| Individual file labels are still obtained from the xattrs on the files |
| themselves. The context option actually sets the aggregate context that |
| fscontext provides, in addition to supplying the same label for individual |
| files. |
| |
| You can set the default security context for unlabeled files using |
| .B defcontext= |
| option. This overrides the value set for unlabeled files in the policy and requires a |
| filesystem that supports xattr labeling. |
| |
| The |
| .B rootcontext= |
| option allows you to explicitly label the root inode of a FS being mounted |
| before that FS or inode becomes visible to userspace. This was found to be |
| useful for things like stateless linux. |
| |
| Note that the kernel rejects any remount request that includes the context |
| option, \fBeven\fP when unchanged from the current context. |
| |
| .BR "Warning: the \fIcontext\fP value might contain commas" , |
| in which case the value has to be properly quoted, otherwise |
| .BR mount (8) |
| will interpret the comma as a separator between mount options. Don't forget that |
| the shell strips off quotes and thus |
| .BR "double quoting is required" . |
| For example: |
| .RS |
| .RS |
| .sp |
| .nf |
| .B mount \-t tmpfs none /mnt \-o \e |
| .B 'context="system_u:object_r:tmp_t:s0:c127,c456",noexec' |
| .fi |
| .sp |
| .RE |
| For more details, see |
| .BR selinux (8). |
| .RE |
| |
| .TP |
| .B defaults |
| Use the default options: |
| .BR rw ", " suid ", " dev ", " exec ", " auto ", " nouser ", and " async . |
| |
| Note that the real set of all default mount options depends on kernel |
| and filesystem type. See the beginning of this section for more details. |
| .TP |
| .B dev |
| Interpret character or block special devices on the filesystem. |
| .TP |
| .B nodev |
| Do not interpret character or block special devices on the file |
| system. |
| .TP |
| .B diratime |
| Update directory inode access times on this filesystem. This is the default. |
| .TP |
| .B nodiratime |
| Do not update directory inode access times on this filesystem. |
| .TP |
| .B dirsync |
| All directory updates within the filesystem should be done synchronously. |
| This affects the following system calls: creat, link, unlink, symlink, |
| mkdir, rmdir, mknod and rename. |
| .TP |
| .B exec |
| Permit execution of binaries. |
| .TP |
| .B noexec |
| Do not permit direct execution of any binaries on the mounted filesystem. |
| (Until recently it was possible to run binaries anyway using a command like |
| /lib/ld*.so /mnt/binary. This trick fails since Linux 2.4.25 / 2.6.0.) |
| .TP |
| .B group |
| Allow an ordinary (i.e., non-root) user to mount the filesystem if one |
| of his groups matches the group of the device. |
| This option implies the options |
| .BR nosuid " and " nodev |
| (unless overridden by subsequent options, as in the option line |
| .BR group,dev,suid ). |
| .TP |
| .B iversion |
| Every time the inode is modified, the i_version field will be incremented. |
| .TP |
| .B noiversion |
| Do not increment the i_version inode field. |
| .TP |
| .B mand |
| Allow mandatory locks on this filesystem. See |
| .BR fcntl (2). |
| .TP |
| .B nomand |
| Do not allow mandatory locks on this filesystem. |
| .TP |
| .B _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). |
| .TP |
| .B nofail |
| Do not report errors for this device if it does not exist. |
| .TP |
| .B relatime |
| Update inode access times relative to modify or change time. Access |
| time is only updated if the previous access time was earlier than the |
| current modify or change time. (Similar to \fBnoatime\fR, but it doesn't |
| break \fBmutt\fR or other applications that need to know if a file has been |
| read since the last time it was modified.) |
| |
| Since Linux 2.6.30, the kernel defaults to the behavior provided by this |
| option (unless |
| .B noatime |
| was specified), and the |
| .B strictatime |
| option is required to obtain traditional semantics. In addition, since Linux |
| 2.6.30, the file's last access time is always updated if it is more than 1 |
| day old. |
| .TP |
| .B norelatime |
| Do not use the |
| .B relatime |
| feature. See also the |
| .B strictatime |
| mount option. |
| .TP |
| .B strictatime |
| Allows to explicitly request full atime updates. This makes it |
| possible for the kernel to default to |
| .B relatime |
| or |
| .B noatime |
| but still allow userspace to override it. For more details about the default |
| system mount options see /proc/mounts. |
| .TP |
| .B nostrictatime |
| Use the kernel's default behavior for inode access time updates. |
| .TP |
| .B suid |
| Allow set-user-identifier or set-group-identifier bits to take |
| effect. |
| .TP |
| .B nosuid |
| Do not allow set-user-identifier or set-group-identifier bits to take |
| effect. |
| .TP |
| .B silent |
| Turn on the silent flag. |
| .TP |
| .B loud |
| Turn off the silent flag. |
| .TP |
| .B owner |
| Allow an ordinary (i.e., non-root) user to mount the filesystem if he |
| is the owner of the device. |
| This option implies the options |
| .BR nosuid " and " nodev |
| (unless overridden by subsequent options, as in the option line |
| .BR owner,dev,suid ). |
| .TP |
| .B remount |
| Attempt to remount an already-mounted filesystem. This is commonly |
| used to change the mount flags for a filesystem, especially to make a |
| readonly filesystem writable. It does not change device or mount point. |
| |
| The remount functionality follows the standard way the mount command works |
| with options from fstab. This means that the mount command only doesn't |
| read fstab (or mtab) when both the |
| .I device |
| and |
| .I dir |
| are specified. |
| |
| .B "mount \-o remount,rw /dev/foo /dir" |
| |
| After this call all old mount options are replaced and arbitrary stuff from |
| fstab is ignored, except the loop= option which is internally generated and |
| maintained by the mount command. |
| |
| .B "mount \-o remount,rw /dir" |
| |
| After this call mount reads fstab (or mtab) and merges these options with |
| the options from the command line (\c |
| .B \-o\c |
| ). |
| .TP |
| .B ro |
| Mount the filesystem read-only. |
| .TP |
| .B rw |
| Mount the filesystem read-write. |
| .TP |
| .B sync |
| All I/O to the filesystem should be done synchronously. In the case of |
| media with a limited number of write cycles |
| (e.g.\& some flash drives), \fBsync\fR may cause life-cycle shortening. |
| .TP |
| .B user |
| Allow an ordinary user to mount the filesystem. |
| The name of the mounting user is written to mtab (or to the private libmount |
| file in /run/mount on system without regular mtab) so that he can unmount the |
| filesystem again. |
| This option implies the options |
| .BR noexec ", " nosuid ", and " nodev |
| (unless overridden by subsequent options, as in the option line |
| .BR user,exec,dev,suid ). |
| .TP |
| .B nouser |
| Forbid an ordinary (i.e., non-root) user to mount the filesystem. |
| This is the default; it does not imply any other options. |
| .TP |
| .B users |
| Allow every user to mount and unmount the filesystem. |
| This option implies the options |
| .BR noexec ", " nosuid ", and " nodev |
| (unless overridden by subsequent options, as in the option line |
| .BR users,exec,dev,suid ). |
| .TP |
| .B x-* |
| All options prefixed with "x-" are interpreted as comments or userspace |
| application-specific options. These options are not stored in the mtab file, |
| nor sent to the mount.<type> helpers nor the |
| .BR mount (2) |
| system call. The suggested format is x-<appname>.<option> (e.g.\& x-systemd.automount). |
| .TP |
| .BR x-mount.mkdir [ = \fImode\fR ] |
| Allow to make a target directory (mountpoint). The optional argument |
| .I mode |
| specifies the filesystem access mode used for |
| .BR mkdir (2) |
| in octal notation. The default mode is 0755. This functionality is supported |
| only for root users. |
| |
| .SH "FILESYSTEM-SPECIFIC MOUNT OPTIONS" |
| The following options apply only to certain filesystems. |
| We sort them by filesystem. They all follow the |
| .B \-o |
| flag. |
| |
| What options are supported depends a bit on the running kernel. |
| More info may be found in the kernel source subdirectory |
| .IR Documentation/filesystems . |
| |
| .SH "Mount options for adfs" |
| .TP |
| \fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP |
| Set the owner and group of the files in the filesystem (default: uid=gid=0). |
| .TP |
| \fBownmask=\fP\,\fIvalue\fP and \fBothmask=\fP\,\fIvalue\fP |
| Set the permission mask for ADFS 'owner' permissions and 'other' permissions, |
| respectively (default: 0700 and 0077, respectively). |
| See also |
| .IR /usr/src/linux/Documentation/filesystems/adfs.txt . |
| .SH "Mount options for affs" |
| .TP |
| \fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP |
| Set the owner and group of the root of the filesystem (default: uid=gid=0, |
| but with option |
| .B uid |
| or |
| .B gid |
| without specified value, the uid and gid of the current process are taken). |
| .TP |
| \fBsetuid=\fP\,\fIvalue\fP and \fBsetgid=\fP\,\fIvalue\fP |
| Set the owner and group of all files. |
| .TP |
| .BI mode= value |
| Set the mode of all files to |
| .IR value " & 0777" |
| disregarding the original permissions. |
| Add search permission to directories that have read permission. |
| The value is given in octal. |
| .TP |
| .B protect |
| Do not allow any changes to the protection bits on the filesystem. |
| .TP |
| .B usemp |
| Set uid and gid of the root of the filesystem to the uid and gid |
| of the mount point upon the first sync or umount, and then |
| clear this option. Strange... |
| .TP |
| .B verbose |
| Print an informational message for each successful mount. |
| .TP |
| .BI prefix= string |
| Prefix used before volume name, when following a link. |
| .TP |
| .BI volume= string |
| Prefix (of length at most 30) used before '/' when following a symbolic link. |
| .TP |
| .BI reserved= value |
| (Default: 2.) Number of unused blocks at the start of the device. |
| .TP |
| .BI root= value |
| Give explicitly the location of the root block. |
| .TP |
| .BI bs= value |
| Give blocksize. Allowed values are 512, 1024, 2048, 4096. |
| .TP |
| .BR grpquota | noquota | quota | usrquota |
| These options are accepted but ignored. |
| (However, quota utilities may react to such strings in |
| .IR /etc/fstab .) |
| .SH "Mount options for btrfs" |
| Btrfs is a copy-on-write filesystem for Linux aimed at |
| implementing advanced features while focusing on fault tolerance, |
| repair, and easy administration. |
| .TP |
| .BI alloc_start= bytes |
| Debugging option to force all block allocations above a certain |
| byte threshold on each block device. The value is specified in |
| bytes, optionally with a K, M, or G suffix, case insensitive. |
| Default is 1MB. |
| .TP |
| .B autodefrag |
| Disable/enable auto defragmentation. |
| Auto defragmentation detects small random writes into files and queues |
| them up for the defrag process. Works best for small files; |
| not well-suited for large database workloads. |
| .TP |
| .BR check_int | check_int_data | check_int_print_mask =\fIvalue\fR |
| These debugging options control the behavior of the integrity checking |
| module(the BTRFS_FS_CHECK_INTEGRITY config option required). |
| |
| .B check_int |
| enables the integrity checker module, which examines all |
| block-write requests to ensure on-disk consistency, at a large |
| memory and CPU cost. |
| |
| .B check_int_data |
| includes extent data in the integrity checks, and |
| implies the check_int option. |
| |
| .B check_int_print_mask |
| takes a bitmask of BTRFSIC_PRINT_MASK_* values |
| as defined in fs/btrfs/check-integrity.c, to control the integrity |
| checker module behavior. |
| |
| See comments at the top of |
| .IR fs/btrfs/check-integrity.c |
| for more info. |
| .TP |
| .BI commit= seconds |
| Set the interval of periodic commit, 30 seconds by default. Higher |
| values defer data being synced to permanent storage, with obvious |
| consequences when the system crashes. The upper bound is not forced, |
| but a warning is printed if it's more than 300 seconds (5 minutes). |
| .TP |
| .BR compress | compress= \fItype\fR| compress-force | compress-force= \fItype\fR |
| Control BTRFS file data compression. Type may be specified as "zlib" |
| "lzo" or "no" (for no compression, used for remounting). If no type |
| is specified, zlib is used. If \fBcompress-force\fR is specified, |
| all files will be compressed, whether or not they compress well. |
| If compression is enabled, \fBnodatacow\fR and \fBnodatasum\fR are disabled. |
| .TP |
| .B degraded |
| Allow mounts to continue with missing devices. A read-write mount may |
| fail with too many devices missing, for example if a stripe member |
| is completely missing. |
| .TP |
| .BI device= devicepath |
| Specify a device during mount so that ioctls on the control device |
| can be avoided. Especially useful when trying to mount a multi-device |
| setup as root. May be specified multiple times for multiple devices. |
| .TP |
| .B discard |
| Disable/enable the discard mount option. |
| The discard function issues frequent commands to let the block device |
| reclaim space freed by the filesystem. |
| This is useful for SSD devices, thinly provisioned |
| LUNs and virtual machine images, but may have a significant |
| performance impact. (The \fBfstrim\fR command is also available to |
| initiate batch trims from userspace.) |
| .TP |
| .B enospc_debug |
| Disable/enable debugging option to be more verbose in some ENOSPC conditions. |
| .TP |
| .BI fatal_errors= action |
| Action to take when encountering a fatal error: |
| "bug" - BUG() on a fatal error. This is the default. |
| "panic" - panic() on a fatal error. |
| .TP |
| .B flushoncommit |
| The |
| .B flushoncommit |
| mount option forces any data dirtied by a write in a |
| prior transaction to commit as part of the current commit. This makes |
| the committed state a fully consistent view of the filesystem from the |
| application's perspective (i.e., it includes all completed filesystem |
| operations). This was previously the behavior only when a snapshot is |
| created. |
| .TP |
| .B inode_cache |
| Enable free inode number caching. Defaults to off due to an overflow |
| problem when the free space CRCs don't fit inside a single page. |
| .TP |
| .BI max_inline= bytes |
| Specify the maximum amount of space, in bytes, that can be inlined in |
| a metadata B-tree leaf. The value is specified in bytes, optionally |
| with a K, M, or G suffix, case insensitive. In practice, this value |
| is limited by the root sector size, with some space unavailable due |
| to leaf headers. For a 4k sectorsize, max inline data is ~3900 bytes. |
| .TP |
| .BI metadata_ratio= value |
| Specify that 1 metadata chunk should be allocated after every |
| .I value |
| data chunks. Off by default. |
| .TP |
| .B noacl |
| Enable/disable support for Posix Access Control Lists (ACLs). See the |
| .BR acl (5) |
| manual page for more information about ACLs. |
| .TP |
| .B nobarrier |
| Enable/disable the use of block-layer write barriers. Write barriers |
| ensure that certain IOs make it through the device cache and are on |
| persistent storage. If disabled on a device with a volatile |
| (non-battery-backed) write-back cache, the \fBnobarrier\fR option will |
| lead to filesystem corruption on a system crash or power loss. |
| .TP |
| .B nodatacow |
| Enable/disable data copy-on-write for newly created files. |
| This option implies \fBnodatasum\fR, and disables all compression. |
| .TP |
| .B nodatasum |
| Enable/disable data checksumming for newly created files. |
| This option implies \fBdatacow\fR. |
| .TP |
| .B notreelog |
| Enable/disable the tree logging used for fsync and O_SYNC writes. |
| .TP |
| .B recovery |
| Enable autorecovery attempts if a bad tree root is found at mount time. |
| Currently this scans a list of several previous tree roots and tries to |
| use the first readable. |
| .TP |
| .B rescan_uuid_tree |
| Force check and rebuild procedure of the UUID tree. This should not |
| normally be needed. |
| .TP |
| .B skip_balance |
| Skip automatic resume of an interrupted balance operation after mount. |
| May be resumed with "btrfs balance resume." |
| .TP |
| .B nospace_cache |
| Disable freespace cache loading without clearing the cache. |
| .TP |
| .B clear_cache |
| Force clearing and rebuilding of the disk space cache if something |
| has gone wrong. |
| .TP |
| .BR ssd | nossd | ssd_spread |
| Options to control ssd allocation schemes. By default, BTRFS will |
| enable or disable ssd allocation heuristics depending on whether a |
| rotational or nonrotational disk is in use. The \fBssd\fR and |
| \fBnossd\fR options can override this autodetection. |
| |
| The \fBssd_spread\fR mount option attempts to allocate into big chunks |
| of unused space, and may perform better on low-end ssds. \fBssd_spread\fR |
| implies \fBssd\fR, enabling all other ssd heuristics as well. |
| .TP |
| .BI subvol= path |
| Mount subvolume at |
| .IR path |
| rather than the root subvolume. The |
| .IR path |
| is relative to the top level subvolume. |
| .TP |
| .BI subvolid= ID |
| Mount subvolume specified by an ID number rather than the root subvolume. |
| This allows mounting of subvolumes which are not in the root of the mounted |
| filesystem. |
| You can use "btrfs subvolume list" to see subvolume ID numbers. |
| .TP |
| .BI subvolrootid= objectid " \fR(deprecated)" |
| Mount subvolume specified by |
| .IR objectid |
| rather than the root subvolume. |
| This allows mounting of subvolumes which are not in the root of the mounted |
| filesystem. |
| You can use "btrfs subvolume show " to see the object ID for a subvolume. |
| .TP |
| .BI thread_pool= number |
| The number of worker threads to allocate. The default number is equal |
| to the number of CPUs + 2, or 8, whichever is smaller. |
| .TP |
| .B user_subvol_rm_allowed |
| Allow subvolumes to be deleted by a non-root user. Use with caution. |
| |
| .SH "Mount options for cifs" |
| See the options section of the |
| .BR mount.cifs (8) |
| man page (cifs-utils package must be installed). |
| |
| .SH "Mount options for coherent" |
| None. |
| |
| .SH "Mount options for debugfs" |
| The debugfs filesystem is a pseudo filesystem, traditionally mounted on |
| .IR /sys/kernel/debug . |
| .\" or just /debug |
| .\" present since 2.6.11 |
| As of kernel version 3.4, debugfs has the following options: |
| .TP |
| .BI uid= n ", gid=" n |
| Set the owner and group of the mountpoint. |
| .TP |
| .BI mode= value |
| Sets the mode of the mountpoint. |
| .SH "Mount options for devpts" |
| The devpts filesystem is a pseudo filesystem, traditionally mounted on |
| .IR /dev/pts . |
| In order to acquire a pseudo terminal, a process opens |
| .IR /dev/ptmx ; |
| the number of the pseudo terminal is then made available to the process |
| and the pseudo terminal slave can be accessed as |
| .IR /dev/pts/ <number>. |
| .TP |
| \fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP |
| 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 |
| .B gid=5 |
| will cause newly created PTYs to belong to the tty group. |
| .TP |
| .BI mode= value |
| Set the mode of newly created PTYs to the specified value. |
| The default is 0600. |
| A value of |
| .B mode=620 |
| and |
| .B gid=5 |
| makes "mesg y" the default on newly created PTYs. |
| .TP |
| \fBnewinstance |
| Create a private instance of devpts filesystem, such that |
| indices of ptys allocated in this new instance are |
| independent of indices created in other instances of devpts. |
| |
| All mounts of devpts without this |
| .B newinstance |
| option share the same set of pty indices (i.e legacy mode). |
| Each mount of devpts with the |
| .B newinstance |
| option has a private set of pty indices. |
| |
| This option is mainly used to support containers in the |
| linux kernel. It is implemented in linux kernel versions |
| starting with 2.6.29. Further, this mount option is valid |
| only if CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the |
| kernel configuration. |
| |
| To use this option effectively, |
| .I /dev/ptmx |
| must be a symbolic link to |
| .I pts/ptmx. |
| See |
| .I Documentation/filesystems/devpts.txt |
| in the linux kernel source tree for details. |
| .TP |
| .BI ptmxmode= value |
| |
| Set the mode for the new |
| .I ptmx |
| device node in the devpts filesystem. |
| |
| With the support for multiple instances of devpts (see |
| .B newinstance |
| option above), each instance has a private |
| .I ptmx |
| node in the root of the devpts filesystem (typically |
| .IR /dev/pts/ptmx ). |
| |
| For compatibility with older versions of the kernel, the |
| default mode of the new |
| .I ptmx |
| node is 0000. |
| .BI ptmxmode= value |
| specifies a more useful mode for the |
| .I ptmx |
| node and is highly recommended when the |
| .B newinstance |
| option is specified. |
| |
| This option is only implemented in linux kernel versions |
| starting with 2.6.29. Further, this option is valid only if |
| CONFIG_DEVPTS_MULTIPLE_INSTANCES is enabled in the kernel |
| configuration. |
| |
| .SH "Mount options for ext" |
| None. |
| Note that the `ext' filesystem is obsolete. Don't use it. |
| Since Linux version 2.1.21 extfs is no longer part of the kernel source. |
| |
| .SH "Mount options for ext2" |
| The `ext2' filesystem is the standard Linux filesystem. |
| .\" Due to a kernel bug, it may be mounted with random mount options |
| .\" (fixed in Linux 2.0.4). |
| Since Linux 2.5.46, for most mount options the default |
| is determined by the filesystem superblock. Set them with |
| .BR tune2fs (8). |
| .TP |
| .BR acl | noacl |
| Support POSIX Access Control Lists (or not). |
| .\" requires CONFIG_EXT2_FS_POSIX_ACL |
| .TP |
| .BR bsddf | minixdf |
| Set the behavior for the |
| .I statfs |
| system call. The |
| .B minixdf |
| behavior is to return in the |
| .I f_blocks |
| field the total number of blocks of the filesystem, while the |
| .B bsddf |
| behavior (which is the default) is to subtract the overhead blocks |
| used by the ext2 filesystem and not available for file storage. Thus |
| .sp 1 |
| % mount /k \-o minixdf; df /k; umount /k |
| .TS |
| tab(#); |
| l2 l2 r2 l2 l2 l |
| l c r c c l. |
| Filesystem#1024-blocks#Used#Available#Capacity#Mounted on |
| /dev/sda6#2630655#86954#2412169#3%#/k |
| .TE |
| .sp 1 |
| % mount /k \-o bsddf; df /k; umount /k |
| .TS |
| tab(#); |
| l2 l2 r2 l2 l2 l |
| l c r c c l. |
| Filesystem#1024-blocks#Used#Available#Capacity#Mounted on |
| /dev/sda6#2543714#13#2412169#0%#/k |
| .TE |
| .sp 1 |
| (Note that this example shows that one can add command-line options |
| to the options given in |
| .IR /etc/fstab .) |
| |
| .TP |
| .BR check=none " or " nocheck |
| No checking is done at mount time. This is the default. This is fast. |
| It is wise to invoke |
| .BR e2fsck (8) |
| every now and then, e.g.\& at boot time. The non-default behavior is unsupported |
| (check=normal and check=strict options have been removed). Note that these mount options |
| don't have to be supported if ext4 kernel driver is used for ext2 and ext3 filesystems. |
| .TP |
| .B debug |
| Print debugging info upon each (re)mount. |
| .TP |
| .BR errors= { continue | remount-ro | panic } |
| Define the behavior when an error is encountered. |
| (Either ignore errors and just mark the filesystem erroneous and continue, |
| or remount the filesystem read-only, or panic and halt the system.) |
| The default is set in the filesystem superblock, and can be |
| changed using |
| .BR tune2fs (8). |
| .TP |
| .BR grpid | bsdgroups " and " nogrpid | sysvgroups |
| These options define what group id a newly created file gets. |
| When |
| .B 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. |
| .TP |
| .BR grpquota | noquota | quota | usrquota |
| The usrquota (same as quota) mount option enables user quota support on the |
| filesystem. grpquota enables group quotas support. You need the quota utilities |
| to actually enable and manage the quota system. |
| .TP |
| .B nouid32 |
| Disables 32-bit UIDs and GIDs. This is for interoperability with older |
| kernels which only store and expect 16-bit values. |
| .TP |
| .BR oldalloc " or " orlov |
| Use old allocator or Orlov allocator for new inodes. Orlov is default. |
| .TP |
| \fBresgid=\fP\,\fIn\fP and \fBresuid=\fP\,\fIn\fP |
| The ext2 filesystem reserves a certain percentage of the available |
| space (by default 5%, see |
| .BR mke2fs (8) |
| and |
| .BR tune2fs (8)). |
| These options determine who can use the reserved blocks. |
| (Roughly: whoever has the specified uid, or belongs to the specified group.) |
| .TP |
| .BI sb= n |
| Instead of block 1, use block |
| .I 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, |
| .B 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 |
| .B mke2fs |
| cannot be mounted r/w under Linux 2.0.*.) |
| The block number here uses 1\ k units. Thus, if you want to use logical |
| block 32768 on a filesystem with 4\ k blocks, use "sb=131072". |
| .TP |
| .BR user_xattr | nouser_xattr |
| Support "user." extended attributes (or not). |
| .\" requires CONFIG_EXT2_FS_XATTR |
| |
| |
| .SH "Mount options for ext3" |
| The ext3 filesystem is a version of the ext2 filesystem which has been |
| enhanced with journaling. It supports the same options as ext2 as |
| well as the following additions: |
| .\" .TP |
| .\" .BR abort |
| .\" Mount the filesystem in abort mode, as if a fatal error has occurred. |
| .TP |
| .B journal=update |
| Update the ext3 filesystem's journal to the current format. |
| .TP |
| .B journal=inum |
| When a journal already exists, this option is ignored. Otherwise, it |
| specifies the number of the inode which will represent the ext3 filesystem's |
| journal file; ext3 will create a new journal, overwriting the old contents |
| of the file whose inode number is |
| .IR inum . |
| .TP |
| .BR journal_dev=devnum / journal_path=path |
| When the external journal device's major/minor numbers |
| have changed, these options allow the user to specify |
| the new journal location. The journal device is |
| identified either through its new major/minor numbers encoded |
| in devnum, or via a path to the device. |
| .TP |
| .BR norecovery / noload |
| Don't load the journal on mounting. Note that |
| if the filesystem was not unmounted cleanly, |
| skipping the journal replay will lead to the |
| filesystem containing inconsistencies that can |
| lead to any number of problems. |
| .TP |
| .BR data= { journal | ordered | writeback } |
| Specifies the journaling mode for file data. Metadata is always journaled. |
| To use modes other than |
| .B ordered |
| on the root filesystem, pass the mode to the kernel as boot parameter, e.g.\& |
| .IR rootflags=data=journal . |
| .RS |
| .TP |
| .B journal |
| All data is committed into the journal prior to being written into the |
| main filesystem. |
| .TP |
| .B 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. |
| .TP |
| .B writeback |
| Data ordering is not preserved \(en data may be written into the main |
| filesystem after its metadata has been committed to the journal. |
| This is rumoured to be the highest-throughput option. It guarantees |
| internal filesystem integrity, however it can allow old data to appear |
| in files after a crash and journal recovery. |
| .RE |
| .TP |
| .B data_err=ignore |
| Just print an error message if an error occurs in a file data buffer in |
| ordered mode. |
| .TP |
| .B data_err=abort |
| Abort the journal if an error occurs in a file data buffer in ordered mode. |
| .TP |
| .BR barrier=0 " / " barrier=1 " |
| This disables / enables the use of write barriers in the jbd code. barrier=0 |
| disables, barrier=1 enables (default). This also requires an IO stack which can |
| support barriers, and if jbd gets an error on a barrier write, it will disable |
| barriers again with a warning. Write barriers enforce proper on-disk ordering |
| of journal commits, making volatile disk write caches safe to use, at some |
| performance penalty. If your disks are battery-backed in one way or another, |
| disabling barriers may safely improve performance. |
| .TP |
| .BI commit= nrsec |
| Sync all data and metadata every |
| .I nrsec |
| seconds. The default value is 5 seconds. Zero means default. |
| .TP |
| .B user_xattr |
| Enable Extended User Attributes. See the |
| .BR attr (5) |
| manual page. |
| .TP |
| .B acl |
| Enable POSIX Access Control Lists. See the |
| .BR acl (5) |
| manual page. |
| .TP |
| .BR usrjquota=aquota.user | grpjquota=aquota.group | jqfmt=vfsv0 |
| Apart from the old quota system (as in ext2, jqfmt=vfsold aka version 1 quota) |
| ext3 also supports journaled quotas (version 2 quota). jqfmt=vfsv0 |
| enables journaled quotas. For journaled quotas the mount options |
| usrjquota=aquota.user and grpjquota=aquota.group are required to tell the |
| quota system which quota database files to use. Journaled quotas have the |
| advantage that even after a crash no quota check is required. |
| |
| .SH "Mount options for ext4" |
| The ext4 filesystem is an advanced level of the ext3 filesystem which |
| incorporates scalability and reliability enhancements for supporting large |
| filesystem. |
| |
| The options |
| .B journal_dev, norecovery, noload, data, commit, orlov, oldalloc, [no]user_xattr |
| .B [no]acl, bsddf, minixdf, debug, errors, data_err, grpid, bsdgroups, nogrpid |
| .B sysvgroups, resgid, resuid, sb, quota, noquota, grpquota, usrquota |
| .B usrjquota, grpjquota and jqfmt |
| are backwardly compatible with ext3 or ext2. |
| .TP |
| .B journal_checksum |
| Enable checksumming of the journal transactions. This will allow the recovery |
| code in e2fsck and the kernel to detect corruption in the kernel. It is a |
| compatible change and will be ignored by older kernels. |
| .TP |
| .B journal_async_commit |
| Commit block can be written to disk without waiting for descriptor blocks. |
| If enabled, older kernels cannot mount the device. |
| This will enable 'journal_checksum' internally. |
| .TP |
| .BR barrier=0 " / " barrier=1 " / " barrier " / " nobarrier |
| These mount options have the same effect as in ext3. The mount options |
| "barrier" and "nobarrier" are added for consistency with other ext4 mount |
| options. |
| |
| The ext4 filesystem enables write barriers by default. |
| .TP |
| .BI inode_readahead_blks= n |
| This tuning parameter controls the maximum number of inode table blocks that |
| ext4's inode table readahead algorithm will pre-read into the buffer cache. |
| The value must be a power of 2. The default value is 32 blocks. |
| .TP |
| .BI stripe= n |
| Number of filesystem blocks that mballoc will try to use for allocation size |
| and alignment. For RAID5/6 systems this should be the number of data disks * |
| RAID chunk size in filesystem blocks. |
| .TP |
| .B delalloc |
| Deferring block allocation until write-out time. |
| .TP |
| .B nodelalloc |
| Disable delayed allocation. Blocks are allocated when data is copied from user |
| to page cache. |
| .TP |
| .BI max_batch_time= usec |
| Maximum amount of time ext4 should wait for additional filesystem operations to |
| be batch together with a synchronous write operation. Since a synchronous |
| write operation is going to force a commit and then a wait for the I/O |
| complete, it doesn't cost much, and can be a huge throughput win, we wait for a |
| small amount of time to see if any other transactions can piggyback on the |
| synchronous write. The algorithm used is designed to automatically tune for |
| the speed of the disk, by measuring the amount of time (on average) that it |
| takes to finish committing a transaction. Call this time the "commit time". |
| If the time that the transaction has been running is less than the commit time, |
| ext4 will try sleeping for the commit time to see if other operations will join |
| the transaction. The commit time is capped by the max_batch_time, which |
| defaults to 15000\ \[mc]s (15\ ms). This optimization can be turned off entirely by |
| setting max_batch_time to 0. |
| .TP |
| .BI min_batch_time= usec |
| This parameter sets the commit time (as described above) to be at least |
| min_batch_time. It defaults to zero microseconds. Increasing this parameter |
| may improve the throughput of multi-threaded, synchronous workloads on very |
| fast disks, at the cost of increasing latency. |
| .TP |
| .BI journal_ioprio= prio |
| The I/O priority (from 0 to 7, where 0 is the highest priority) which should be |
| used for I/O operations submitted by kjournald2 during a commit operation. |
| This defaults to 3, which is a slightly higher priority than the default I/O |
| priority. |
| .TP |
| .B abort |
| Simulate the effects of calling ext4_abort() for |
| debugging purposes. This is normally used while |
| remounting a filesystem which is already mounted. |
| .TP |
| .BR auto_da_alloc | noauto_da_alloc |
| Many broken applications don't use fsync() when |
| replacing existing files via patterns such as |
| |
| fd = open("foo.new")/write(fd,...)/close(fd)/ rename("foo.new", "foo") |
| |
| or worse yet |
| |
| fd = open("foo", O_TRUNC)/write(fd,...)/close(fd). |
| |
| If auto_da_alloc is enabled, ext4 will detect the replace-via-rename and |
| replace-via-truncate patterns and force that any delayed allocation blocks are |
| allocated such that at the next journal commit, in the default data=ordered |
| mode, the data blocks of the new file are forced to disk before the rename() |
| operation is committed. This provides roughly the same level of guarantees as |
| ext3, and avoids the "zero-length" problem that can happen when a system |
| crashes before the delayed allocation blocks are forced to disk. |
| .TP |
| .B noinit_itable |
| Do not initialize any uninitialized inode table blocks in the background. This |
| feature may be used by installation CD's so that the install process can |
| complete as quickly as possible; the inode table initialization process would |
| then be deferred until the next time the filesystem is mounted. |
| .TP |
| .B init_itable=n |
| The lazy itable init code will wait n times the number of milliseconds it took |
| to zero out the previous block group's inode table. This minimizes the impact on |
| system performance while the filesystem's inode table is being initialized. |
| .TP |
| .BR discard / nodiscard |
| Controls whether ext4 should issue discard/TRIM commands to the underlying |
| block device when blocks are freed. This is useful for SSD devices and |
| sparse/thinly-provisioned LUNs, but it is off by default until sufficient |
| testing has been done. |
| .TP |
| .B nouid32 |
| Disables 32-bit UIDs and GIDs. This is for |
| interoperability with older kernels which only |
| store and expect 16-bit values. |
| .TP |
| .BR block_validity / noblock_validity |
| This options allows to enables/disables the in-kernel facility for tracking |
| filesystem metadata blocks within internal data structures. This allows multi-\c |
| block allocator and other routines to quickly locate extents which might |
| overlap with filesystem metadata blocks. This option is intended for debugging |
| purposes and since it negatively affects the performance, it is off by default. |
| .TP |
| .BR dioread_lock / dioread_nolock |
| Controls whether or not ext4 should use the DIO read locking. If the |
| dioread_nolock option is specified ext4 will allocate uninitialized extent |
| before buffer write and convert the extent to initialized after IO completes. |
| This approach allows ext4 code to avoid using inode mutex, which improves |
| scalability on high speed storages. However this does not work with data |
| journaling and dioread_nolock option will be ignored with kernel warning. |
| Note that dioread_nolock code path is only used for extent-based files. |
| Because of the restrictions this options comprises it is off by default |
| (e.g.\& dioread_lock). |
| .TP |
| .B max_dir_size_kb=n |
| This limits the size of the directories so that any attempt to expand them |
| beyond the specified limit in kilobytes will cause an ENOSPC error. This is |
| useful in memory-constrained environments, where a very large directory can |
| cause severe performance problems or even provoke the Out Of Memory killer. (For |
| example, if there is only 512\ MB memory available, a 176\ MB directory may |
| seriously cramp the system's style.) |
| .TP |
| .B i_version |
| Enable 64-bit inode version support. This option is off by default. |
| |
| .SH "Mount options for fat" |
| (Note: |
| .I fat |
| is not a separate filesystem, but a common part of the |
| .IR msdos , |
| .I umsdos |
| and |
| .I vfat |
| filesystems.) |
| .TP |
| .BR blocksize= { 512 | 1024 | 2048 } |
| Set blocksize (default 512). This option is obsolete. |
| .TP |
| \fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP |
| Set the owner and group of all files. |
| (Default: the uid and gid of the current process.) |
| .TP |
| .BI umask= value |
| Set the umask (the bitmask of the permissions that are |
| .B not |
| present). The default is the umask of the current process. |
| The value is given in octal. |
| .TP |
| .BI 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 Linux 2.5.43. |
| .TP |
| .BI 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 Linux 2.5.43. |
| .TP |
| .BI allow_utime= value |
| This option controls the permission check of mtime/atime. |
| .RS |
| .TP |
| .B 20 |
| If current process is in group of file's group ID, you can change timestamp. |
| .TP |
| .B 2 |
| Other users can change timestamp. |
| .PP |
| The default is set from `dmask' option. (If the directory is writable, |
| .BR utime (2) |
| is also allowed. I.e.\& \s+3~\s0dmask & 022) |
| |
| Normally |
| .BR utime (2) |
| checks current process is owner of the file, or it has |
| CAP_FOWNER capability. But FAT filesystem doesn't have uid/gid on disk, so |
| normal check is too inflexible. With this option you can relax it. |
| .RE |
| .TP |
| .BI check= value |
| Three different levels of pickiness can be chosen: |
| .RS |
| .TP |
| .BR r [ elaxed ] |
| Upper and lower case are accepted and equivalent, long name parts are |
| truncated (e.g.\& |
| .I verylongname.foobar |
| becomes |
| .IR verylong.foo ), |
| leading and embedded spaces are accepted in each name part (name and extension). |
| .TP |
| .BR n [ ormal ] |
| Like "relaxed", but many special characters (*, ?, <, spaces, etc.) are |
| rejected. This is the default. |
| .TP |
| .BR s [ trict ] |
| Like "normal", but names that contain long parts or special characters |
| that are sometimes used on Linux but are not accepted by MS-DOS |
| (+, =, etc.) are rejected. |
| .RE |
| .TP |
| .BI codepage= value |
| Sets the codepage for converting to shortname characters on FAT |
| and VFAT filesystems. By default, codepage 437 is used. |
| .TP |
| .BI conv= mode |
| The |
| .I fat |
| filesystem can perform CRLF<-->NL conversion (MS-DOS text format to UNIX text |
| format) in the kernel. The following conversion \fImode\fRs are available: |
| .RS |
| .TP |
| .BR b [ inary ] |
| No translation is performed. This is the default. |
| .TP |
| .BR t [ ext ] |
| CRLF<-->NL translation is performed on all files. |
| .TP |
| .BR a [ uto ] |
| 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 |
| .I 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). |
| .PP |
| Programs that do computed lseeks won't like in-kernel text conversion. |
| Several people have had their data ruined by this translation. Beware! |
| |
| For filesystems mounted in binary mode, a conversion tool |
| (fromdos/todos) is available. This option is obsolete. |
| .RE |
| .TP |
| .BI cvf_format= module |
| Forces the driver to use the CVF (Compressed Volume File) module |
| .RI cvf_ module |
| instead of auto-detection. If the kernel supports kmod, the |
| cvf_format=xxx option also controls on-demand CVF module loading. |
| This option is obsolete. |
| .TP |
| .BI cvf_option= option |
| Option passed to the CVF module. This option is obsolete. |
| .TP |
| .B debug |
| Turn on the |
| .I debug |
| flag. A version string and a list of filesystem parameters will be |
| printed (these data are also printed if the parameters appear to be |
| inconsistent). |
| .TP |
| .B discard |
| If set, causes discard/TRIM commands to be issued to the block device |
| when blocks are freed. This is useful for SSD devices and |
| sparse/thinly-provisioned LUNs. |
| .TP |
| .BR fat= {12 | 16 | 32 } |
| Specify a 12, 16 or 32 bit fat. This overrides |
| the automatic FAT type detection routine. Use with caution! |
| .TP |
| .BI 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. |
| .TP |
| .B nfs |
| If set, enables in-memory indexing of directory inodes to reduce the |
| frequency of ESTALE errors in NFS client operations. Useful only when |
| the filesystem is exported via NFS. |
| .TP |
| .BI tz=UTC |
| This option disables the conversion of timestamps |
| between local time (as used by Windows on FAT) and UTC |
| (which Linux uses internally). This is particularly |
| useful when mounting devices (like digital cameras) |
| that are set to UTC in order to avoid the pitfalls of |
| local time. |
| .TP |
| .B quiet |
| Turn on the |
| .I quiet |
| flag. Attempts to chown or chmod files do not return errors, |
| although they fail. Use with caution! |
| .TP |
| .B showexec |
| If set, the execute permission bits of the file will be allowed only if |
| the extension part of the name is \&.EXE, \&.COM, or \&.BAT. Not set by default. |
| .TP |
| .B sys_immutable |
| If set, ATTR_SYS attribute on FAT is handled as IMMUTABLE flag on Linux. |
| Not set by default. |
| .TP |
| .B flush |
| If set, the filesystem will try to flush to disk more early than normal. |
| Not set by default. |
| .TP |
| .B usefree |
| Use the "free clusters" value stored on FSINFO. It'll |
| be used to determine number of free clusters without |
| scanning disk. But it's not used by default, because |
| recent Windows don't update it correctly in some |
| case. If you are sure the "free clusters" on FSINFO is |
| correct, by this option you can avoid scanning disk. |
| .TP |
| .BR dots ", " nodots ", " dotsOK= [ yes | no ] |
| Various misguided attempts to force Unix or DOS conventions |
| onto a FAT filesystem. |
| |
| .SH "Mount options for hfs" |
| .TP |
| .BI creator= cccc ", type=" cccc |
| Set the creator/type values as shown by the MacOS finder |
| used for creating new files. Default values: '????'. |
| .TP |
| .BI uid= n ", gid=" n |
| Set the owner and group of all files. |
| (Default: the uid and gid of the current process.) |
| .TP |
| .BI dir_umask= n ", file_umask=" n ", umask=" n |
| Set the umask used for all directories, all regular files, or all |
| files and directories. Defaults to the umask of the current process. |
| .TP |
| .BI session= n |
| 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. |
| .TP |
| .BI part= n |
| Select partition number n from the device. |
| Only makes sense for CDROMs. |
| Defaults to not parsing the partition table at all. |
| .TP |
| .B quiet |
| Don't complain about invalid mount options. |
| |
| .SH "Mount options for hpfs" |
| .TP |
| \fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP |
| Set the owner and group of all files. (Default: the uid and gid |
| of the current process.) |
| .TP |
| .BI umask= value |
| Set the umask (the bitmask of the permissions that are |
| .B not |
| present). The default is the umask of the current process. |
| The value is given in octal. |
| .TP |
| .BR case= { lower | asis } |
| Convert all files names to lower case, or leave them. |
| (Default: |
| .BR case=lower .) |
| .TP |
| .BR conv= { binary | text | auto } |
| For |
| .BR conv=text , |
| delete some random CRs (in particular, all followed by NL) |
| when reading a file. |
| For |
| .BR conv=auto , |
| choose more or less at random between |
| .BR conv=binary " and " conv=text . |
| For |
| .BR conv=binary , |
| just read what is in the file. This is the default. |
| .TP |
| .B nocheck |
| Do not abort mounting when certain consistency checks fail. |
| |
| .SH "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 |
| .I udf |
| filesystem.) |
| |
| Normal |
| .I 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 filesystem (except |
| that it is read-only, of course). |
| .TP |
| .B norock |
| Disable the use of Rock Ridge extensions, even if available. Cf.\& |
| .BR map . |
| .TP |
| .B nojoliet |
| Disable the use of Microsoft Joliet extensions, even if available. Cf.\& |
| .BR map . |
| .TP |
| .BR check= { r [ elaxed ]| s [ trict ]} |
| With |
| .BR check=relaxed , |
| a filename is first converted to lower case before doing the lookup. |
| This is probably only meaningful together with |
| .B norock |
| and |
| .BR map=normal . |
| (Default: |
| .BR check=strict .) |
| .TP |
| \fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP |
| Give all files in the filesystem the indicated user or group id, |
| possibly overriding the information found in the Rock Ridge extensions. |
| (Default: |
| .BR uid=0,gid=0 .) |
| .TP |
| .BR map= { n [ ormal ]| o [ ff ]| a [ corn ]} |
| For non-Rock Ridge volumes, normal name translation maps upper |
| to lower case ASCII, drops a trailing `;1', and converts `;' to `.'. |
| With |
| .B map=off |
| no name translation is done. See |
| .BR norock . |
| (Default: |
| .BR map=normal .) |
| .B map=acorn |
| is like |
| .B map=normal |
| but also apply Acorn extensions if present. |
| .TP |
| .BI mode= value |
| For non-Rock Ridge volumes, give all files the indicated mode. |
| (Default: read and execute 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.) |
| .TP |
| .B unhide |
| 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.) |
| .TP |
| .BR block= { 512 | 1024 | 2048 } |
| Set the block size to the indicated value. |
| (Default: |
| .BR block=1024 .) |
| .TP |
| .BR conv= { a [ uto ]| b [ inary ]| m [ text ]| t [ ext ]} |
| (Default: |
| .BR 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.) |
| .TP |
| .B 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 16\ MB. |
| .TP |
| .BI session= x |
| Select number of session on multisession CD. (Since 2.3.4.) |
| .TP |
| .BI sbsector= xxx |
| Session begins from sector xxx. (Since 2.3.4.) |
| .LP |
| The following options are the same as for vfat and specifying them only makes |
| sense when using discs encoded using Microsoft's Joliet extensions. |
| .TP |
| .BI iocharset= value |
| Character set to use for converting 16 bit Unicode characters on CD |
| to 8 bit characters. The default is iso8859-1. |
| .TP |
| .B utf8 |
| Convert 16 bit Unicode characters on CD to UTF-8. |
| |
| .SH "Mount options for jfs" |
| .TP |
| .BI iocharset= name |
| Character set to use for converting from Unicode to ASCII. The default is |
| to do no conversion. Use |
| .B iocharset=utf8 |
| for UTF8 translations. This requires CONFIG_NLS_UTF8 to be set in |
| the kernel |
| .I ".config" |
| file. |
| .TP |
| .BI resize= value |
| Resize the volume to |
| .I 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 |
| .B resize |
| keyword with no value will grow the volume to the full size of the partition. |
| .TP |
| .B nointegrity |
| 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 ends. |
| .TP |
| .B integrity |
| Default. Commit metadata changes to the journal. Use this option to remount |
| a volume where the |
| .B nointegrity |
| option was previously specified in order to restore normal behavior. |
| .TP |
| .BR errors= { continue | remount-ro | panic } |
| Define the behavior when an error is encountered. |
| (Either ignore errors and just mark the filesystem erroneous and continue, |
| or remount the filesystem read-only, or panic and halt the system.) |
| .TP |
| .BR noquota | quota | usrquota | grpquota |
| These options are accepted but ignored. |
| |
| .SH "Mount options for minix" |
| None. |
| |
| .SH "Mount options for msdos" |
| See mount options for fat. |
| If the |
| .I msdos |
| filesystem detects an inconsistency, it reports an error and sets the file |
| system read-only. The filesystem can be made writable again by remounting |
| it. |
| |
| .SH "Mount options for ncpfs" |
| Just like |
| .IR nfs ", the " ncpfs |
| implementation expects a binary argument (a |
| .IR "struct ncp_mount_data" ) |
| to the mount system call. This argument is constructed by |
| .BR ncpmount (8) |
| and the current version of |
| .B mount |
| (2.12) does not know anything about ncpfs. |
| |
| .SH "Mount options for nfs and nfs4" |
| See the options section of the |
| .BR nfs (5) |
| man page (nfs-utils package must be installed). |
| |
| The |
| .IR nfs " and " nfs4 |
| implementation expects a binary argument (a |
| .IR "struct nfs_mount_data" ) |
| to the mount system call. This argument is constructed by |
| .BR mount.nfs (8) |
| and the current version of |
| .B mount |
| (2.13) does not know anything about nfs and nfs4. |
| |
| .SH "Mount options for ntfs" |
| .TP |
| .BI iocharset= name |
| Character set to use when returning file names. |
| Unlike VFAT, NTFS suppresses names that contain |
| nonconvertible characters. Deprecated. |
| .\" since 2.5.11 |
| .TP |
| .BI nls= name |
| New name for the option earlier called |
| .IR iocharset . |
| .\" since 2.5.11 |
| .TP |
| .B utf8 |
| Use UTF-8 for converting file names. |
| .TP |
| .BR 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. |
| .TP |
| .B posix=[0|1] |
| If enabled (posix=1), the filesystem distinguishes between |
| upper and lower case. The 8.3 alias names are presented as |
| hard links instead of being suppressed. This option is obsolete. |
| .TP |
| \fBuid=\fP\,\fIvalue\fP, \fBgid=\fP\,\fIvalue\fP and \fBumask=\fP\,\fIvalue\fP |
| 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. |
| |
| .SH "Mount options for proc" |
| .TP |
| \fBuid=\fP\,\fIvalue\fP and \fBgid=\fP\,\fIvalue\fP |
| These options are recognized, but have no effect as far as I can see. |
| |
| .SH "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. |
| |
| .SH "Mount options for reiserfs" |
| Reiserfs is a journaling filesystem. |
| .TP |
| .B conv |
| Instructs version 3.6 reiserfs software to mount a version 3.5 filesystem, |
| using the 3.6 format for newly created objects. This filesystem will no |
| longer be compatible with reiserfs 3.5 tools. |
| .TP |
| .BR hash= { rupasov | tea | r5 | detect } |
| Choose which hash function reiserfs will use to find files within directories. |
| .RS |
| .TP |
| .B 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. |
| .TP |
| .B 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 some CPU cost. |
| This may be used if EHASHCOLLISION errors are experienced with the r5 hash. |
| .TP |
| .B r5 |
| A modified version of the rupasov hash. It is used by default and is |
| the best choice unless the filesystem has huge directories and |
| unusual file-name patterns. |
| .TP |
| .B detect |
| Instructs |
| .I mount |
| to detect which hash function is in use by examining |
| the filesystem being mounted, and to write this information into |
| the reiserfs superblock. This is only useful on the first mount of |
| an old format filesystem. |
| .RE |
| .TP |
| .B hashed_relocation |
| Tunes the block allocator. This may provide performance improvements |
| in some situations. |
| .TP |
| .B no_unhashed_relocation |
| Tunes the block allocator. This may provide performance improvements |
| in some situations. |
| .TP |
| .B noborder |
| Disable the border allocator algorithm invented by Yury Yu. Rupasov. |
| This may provide performance improvements in some situations. |
| .TP |
| .B nolog |
| Disable journaling. 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 journaling |
| operations, save for actual writes into its journaling area. Implementation |
| of |
| .I nolog |
| is a work in progress. |
| .TP |
| .B notail |
| By default, reiserfs stores small files and `file tails' directly into its |
| tree. This confuses some utilities such as |
| .BR LILO (8). |
| This option is used to disable packing of files into the tree. |
| .TP |
| .B replayonly |
| Replay the transactions which are in the journal, but do not actually |
| mount the filesystem. Mainly used by |
| .IR reiserfsck . |
| .TP |
| .BI resize= number |
| A remount option which permits online expansion of reiserfs partitions. |
| Instructs reiserfs to assume that the device has |
| .I number |
| blocks. |
| This option is designed for use with devices which are under logical |
| volume management (LVM). |
| There is a special |
| .I resizer |
| utility which can be obtained from |
| .IR ftp://ftp.namesys.com/pub/reiserfsprogs . |
| .TP |
| .B user_xattr |
| Enable Extended User Attributes. See the |
| .BR attr (5) |
| manual page. |
| .TP |
| .B acl |
| Enable POSIX Access Control Lists. See the |
| .BR acl (5) |
| manual page. |
| .TP |
| .BR barrier=none " / " barrier=flush " |
| This disables / enables the use of write barriers in the journaling code. |
| barrier=none disables, barrier=flush enables (default). This also requires an |
| IO stack which can support barriers, and if reiserfs gets an error on a barrier |
| write, it will disable barriers again with a warning. Write barriers enforce |
| proper on-disk ordering of journal commits, making volatile disk write caches |
| safe to use, at some performance penalty. If your disks are battery-backed in |
| one way or another, disabling barriers may safely improve performance. |
| |
| .SH "Mount options for romfs" |
| None. |
| |
| .SH "Mount options for squashfs" |
| None. |
| |
| .SH "Mount options for smbfs" |
| Just like |
| .IR nfs ", the " smbfs |
| implementation expects a binary argument (a |
| .IR "struct smb_mount_data" ) |
| to the mount system call. This argument is constructed by |
| .BR smbmount (8) |
| and the current version of |
| .B mount |
| (2.12) does not know anything about smbfs. |
| |
| .SH "Mount options for sysv" |
| None. |
| |
| .SH "Mount options for tmpfs" |
| .TP |
| .BI size= nbytes |
| Override default maximum size of the filesystem. |
| The size is given in bytes, and rounded up to entire pages. |
| The default is half of the memory. The size parameter also accepts a suffix % |
| to limit this tmpfs instance to that percentage of your physical RAM: |
| the default, when neither size nor nr_blocks is specified, is size=50% |
| .TP |
| .B nr_blocks= |
| The same as size, but in blocks of PAGE_CACHE_SIZE |
| .TP |
| .B nr_inodes= |
| The maximum number of inodes for this instance. The default |
| is half of the number of your physical RAM pages, or (on a |
| machine with highmem) the number of lowmem RAM pages, |
| whichever is the lower. |
| .PP |
| The tmpfs mount options for sizing (\c |
| .BR size , |
| .BR nr_blocks , |
| and |
| .BR nr_inodes ) |
| accept a suffix |
| .BR k , |
| .B m |
| or |
| .B g |
| for Ki, Mi, Gi (binary kilo (kibi), binary mega (mebi) and binary giga (gibi)) and can be changed on remount. |
| |
| .TP |
| .B mode= |
| Set initial permissions of the root directory. |
| .TP |
| .B uid= |
| The user id. |
| .TP |
| .B gid= |
| The group id. |
| .TP |
| .B mpol=[default|prefer:Node|bind:NodeList|interleave|interleave:NodeList] |
| Set the NUMA memory allocation policy for all files in that |
| instance (if the kernel CONFIG_NUMA is enabled) \(en which can be adjusted on the |
| fly via 'mount \-o remount \&...' |
| .RS |
| .TP |
| .B default |
| prefers to allocate memory from the local node |
| .TP |
| .B prefer:Node |
| prefers to allocate memory from the given Node |
| .TP |
| .B bind:NodeList |
| allocates memory only from nodes in NodeList |
| .TP |
| .B interleave |
| prefers to allocate from each node in turn |
| .TP |
| .B interleave:NodeList |
| allocates from each node of NodeList in turn. |
| .PP |
| The NodeList format is a comma-separated list of decimal numbers and ranges, a |
| range being two "hyphen-minus"-separated decimal numbers, the smallest and largest node |
| numbers in the range. For example, mpol=bind:0\(en3,5,7,9\(en15 |
| |
| Note that trying to mount a tmpfs with an mpol option will fail if the |
| running kernel does not support NUMA; and will fail if its nodelist |
| specifies a node which is not online. If your system relies on that |
| tmpfs being mounted, but from time to time runs a kernel built without |
| NUMA capability (perhaps a safe recovery kernel), or with fewer nodes |
| online, then it is advisable to omit the mpol option from automatic |
| mount options. It can be added later, when the tmpfs is already mounted |
| on MountPoint, by 'mount \-o remount,mpol=Policy:NodeList MountPoint'. |
| |
| .SH "Mount options for ubifs" |
| UBIFS is a flash file system which works on top of UBI volumes. Note that |
| .B |
| atime |
| is not supported and is always turned off. |
| .TP |
| The device name may be specified as |
| .RS |
| .B ubiX_Y |
| UBI device number |
| .BR X , |
| volume number |
| .B Y |
| .TP |
| .B ubiY |
| UBI device number |
| .BR 0 , |
| volume number |
| .B Y |
| .TP |
| .B ubiX:NAME |
| UBI device number |
| .BR X , |
| volume with name |
| .B NAME |
| .TP |
| .B ubi:NAME |
| UBI device number |
| .BR 0 , |
| volume with name |
| .B NAME |
| .RE |
| Alternative |
| .B ! |
| separator may be used instead of |
| .BR : . |
| .TP |
| The following mount options are available: |
| .TP |
| .B bulk_read |
| Enable bulk-read. VFS read-ahead is disabled because it slows down the file |
| system. Bulk-Read is an internal optimization. Some flashes may read faster if |
| the data are read at one go, rather than at several read requests. For |
| example, OneNAND can do "read-while-load" if it reads more than one NAND page. |
| .TP |
| .B no_bulk_read |
| Do not bulk-read. This is the default. |
| .TP |
| .B chk_data_crc |
| Check data CRC-32 checksums. This is the default. |
| .TP |
| .BR no_chk_data_crc . |
| Do not check data CRC-32 checksums. With this option, the filesystem does not |
| check CRC-32 checksum for data, but it does check it for the internal indexing |
| information. This option only affects reading, not writing. CRC-32 is always |
| calculated when writing the data. |
| .TP |
| .BR compr= { none | lzo | zlib } |
| Select the default compressor which is used when new files are written. It is |
| still possible to read compressed files if mounted with the |
| .B none |
| option. |
| |
| .SH "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 |
| .IR iso9660 . |
| .TP |
| .B gid= |
| Set the default group. |
| .TP |
| .B umask= |
| Set the default umask. |
| The value is given in octal. |
| .TP |
| .B uid= |
| Set the default user. |
| .TP |
| .B unhide |
| Show otherwise hidden files. |
| .TP |
| .B undelete |
| Show deleted files in lists. |
| .TP |
| .B nostrict |
| Unset strict conformance. |
| .\" .TP |
| .\" .B utf8 |
| .\" (unused). |
| .TP |
| .B iocharset |
| Set the NLS character set. |
| .TP |
| .B bs= |
| Set the block size. (May not work unless 2048.) |
| .TP |
| .B novrs |
| Skip volume sequence recognition. |
| .TP |
| .B session= |
| Set the CDROM session counting from 0. Default: last session. |
| .TP |
| .B anchor= |
| Override standard anchor location. Default: 256. |
| .TP |
| .B volume= |
| Override the VolumeDesc location. (unused) |
| .TP |
| .B partition= |
| Override the PartitionDesc location. (unused) |
| .TP |
| .B lastblock= |
| Set the last block of the filesystem. |
| .TP |
| .B fileset= |
| Override the fileset block location. (unused) |
| .TP |
| .B rootdir= |
| Override the root directory location. (unused) |
| |
| .SH "Mount options for ufs" |
| .TP |
| .BI ufstype= value |
| UFS is a filesystem 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: |
| .RS |
| .TP |
| .B old |
| Old format of ufs, this is the default, read only. |
| (Don't forget to give the \-r option.) |
| .TP |
| .B 44bsd |
| For filesystems created by a BSD-like system (NetBSD, FreeBSD, OpenBSD). |
| .TP |
| .B ufs2 |
| Used in FreeBSD 5.x supported as read-write. |
| .TP |
| .B 5xbsd |
| Synonym for ufs2. |
| .TP |
| .B sun |
| For filesystems created by SunOS or Solaris on Sparc. |
| .TP |
| .B sunx86 |
| For filesystems created by Solaris on x86. |
| .TP |
| .B hp |
| For filesystems created by HP-UX, read-only. |
| .TP |
| .B nextstep |
| For filesystems created by NeXTStep (on NeXT station) (currently read only). |
| .TP |
| .B nextstep-cd |
| For NextStep CDROMs (block_size == 2048), read-only. |
| .TP |
| .B openstep |
| For filesystems created by OpenStep (currently read only). |
| The same filesystem type is also used by Mac OS X. |
| .RE |
| |
| .TP |
| .BI onerror= value |
| Set behavior on error: |
| .RS |
| .TP |
| .B panic |
| If an error is encountered, cause a kernel panic. |
| .TP |
| .RB [ lock | umount | repair ] |
| These mount options don't do anything at present; |
| when an error is encountered only a console message is printed. |
| .RE |
| |
| .SH "Mount options for umsdos" |
| See mount options for msdos. |
| The |
| .B dotsOK |
| option is explicitly killed by |
| .IR umsdos . |
| |
| .SH "Mount options for vfat" |
| First of all, the mount options for |
| .I fat |
| are recognized. |
| The |
| .B dotsOK |
| option is explicitly killed by |
| .IR vfat . |
| Furthermore, there are |
| .TP |
| .B 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 invalid on the vfat filesystem. The escape sequence |
| that gets used, where u is the Unicode character, |
| is: ':', (u & 0x3f), ((u>>6) & 0x3f), (u>>12). |
| .TP |
| .B posix |
| Allow two files with names that only differ in case. |
| This option is obsolete. |
| .TP |
| .B nonumtail |
| First try to make a short name without sequence number, |
| before trying |
| .IR name\s+3~\s0num.ext . |
| .TP |
| .B utf8 |
| UTF8 is the filesystem safe 8-bit encoding of Unicode that is used by the |
| console. It can be enabled for the filesystem with this option or disabled |
| with utf8=0, utf8=no or utf8=false. If `uni_xlate' gets set, UTF8 gets |
| disabled. |
| .TP |
| .BI shortname= mode |
| Defines the behavior for creation and display of filenames which fit into |
| 8.3 characters. If a long name for a file exists, it will always be the |
| preferred one for display. There are four \fImode\fRs: |
| .RS |
| .TP |
| .B lower |
| Force the short name to lower case upon display; store a long name when |
| the short name is not all upper case. |
| .TP |
| .B win95 |
| Force the short name to upper case upon display; store a long name when |
| the short name is not all upper case. |
| .TP |
| .B winnt |
| Display the short name as is; store a long name when the short name is |
| not all lower case or all upper case. |
| .TP |
| .B mixed |
| Display the short name as is; store a long name when the short name is not |
| all upper case. This mode is the default since Linux 2.6.32. |
| .RE |
| |
| |
| .SH "Mount options for usbfs" |
| .TP |
| \fBdevuid=\fP\,\fIuid\fP and \fBdevgid=\fP\,\fIgid\fP and \fBdevmode=\fP\,\fImode\fP |
| Set the owner and group and mode of the device files in the usbfs filesystem |
| (default: uid=gid=0, mode=0644). The mode is given in octal. |
| .TP |
| \fBbusuid=\fP\,\fIuid\fP and \fBbusgid=\fP\,\fIgid\fP and \fBbusmode=\fP\,\fImode\fP |
| Set the owner and group and mode of the bus directories in the usbfs |
| filesystem (default: uid=gid=0, mode=0555). The mode is given in octal. |
| .TP |
| \fBlistuid=\fP\,\fIuid\fP and \fBlistgid=\fP\,\fIgid\fP and \fBlistmode=\fP\,\fImode\fP |
| Set the owner and group and mode of the file |
| .I devices |
| (default: uid=gid=0, mode=0444). The mode is given in octal. |
| |
| .SH "Mount options for xenix" |
| None. |
| |
| .SH "Mount options for xfs" |
| .TP |
| .BI allocsize= size |
| Sets the buffered I/O end-of-file preallocation size when |
| doing delayed allocation writeout. Valid values for this |
| option are page size (typically 4KiB) through to 1GiB, |
| inclusive, in power-of-2 increments. |
| .sp |
| The default behavior is for dynamic end-of-file |
| preallocation size, which uses a set of heuristics to |
| optimise the preallocation size based on the current |
| allocation patterns within the file and the access patterns |
| to the file. Specifying a fixed allocsize value turns off |
| the dynamic behavior. |
| .TP |
| .BR attr2 | noattr2 |
| The options enable/disable an "opportunistic" improvement to |
| be made in the way inline extended attributes are stored |
| on-disk. When the new form is used for the first time when |
| attr2 is selected (either when setting or removing extended |
| attributes) the on-disk superblock feature bit field will be |
| updated to reflect this format being in use. |
| .sp |
| The default behavior is determined by the on-disk feature |
| bit indicating that attr2 behavior is active. If either |
| mount option it set, then that becomes the new default used |
| by the filesystem. |
| .sp |
| CRC enabled filesystems always use the attr2 format, and so |
| will reject the noattr2 mount option if it is set. |
| .TP |
| .BR barrier | nobarrier |
| Enables/disables the use of block layer write barriers for |
| writes into the journal and for data integrity operations. |
| This allows for drive level write caching to be enabled, for |
| devices that support write barriers. |
| .TP |
| .BR discard | nodiscard |
| Enable/disable the issuing of commands to let the block |
| device reclaim space freed by the filesystem. This is |
| useful for SSD devices, thinly provisioned LUNs and virtual |
| machine images, but may have a performance impact. |
| .sp |
| Note: It is currently recommended that you use the fstrim |
| application to discard unused blocks rather than the discard |
| mount option because the performance impact of this option |
| is quite severe. |
| .TP |
| .BR grpid | bsdgroups | nogrpid | 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 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. |
| .TP |
| .B filestreams |
| Make the data allocator use the filestreams allocation mode |
| across the entire filesystem rather than just on directories |
| configured to use it. |
| .TP |
| .BR ikeep | noikeep |
| When ikeep is specified, XFS does not delete empty inode |
| clusters and keeps them around on disk. When noikeep is |
| specified, empty inode clusters are returned to the free |
| space pool. |
| .TP |
| .BR inode32 | inode64 |
| When inode32 is specified, it indicates that XFS limits |
| inode creation to locations which will not result in inode |
| numbers with more than 32 bits of significance. |
| .sp |
| When inode64 is specified, it indicates that XFS is allowed |
| to create inodes at any location in the filesystem, |
| including those which will result in inode numbers occupying |
| more than 32 bits of significance. |
| .sp |
| inode32 is provided for backwards compatibility with older |
| systems and applications, since 64 bits inode numbers might |
| cause problems for some applications that cannot handle |
| large inode numbers. If applications are in use which do |
| not handle inode numbers bigger than 32 bits, the inode32 |
| option should be specified. |
| .TP |
| .BR largeio | nolargeio |
| If "nolargeio" is specified, the optimal I/O reported in |
| st_blksize by stat(2) will be as small as possible to allow |
| user applications to avoid inefficient read/modify/write |
| I/O. This is typically the page size of the machine, as |
| this is the granularity of the page cache. |
| .sp |
| If "largeio" specified, a filesystem that was created with a |
| "swidth" specified will return the "swidth" value (in bytes) |
| in st_blksize. If the filesystem does not have a "swidth" |
| specified but does specify an "allocsize" then "allocsize" |
| (in bytes) will be returned instead. Otherwise the behavior |
| is the same as if "nolargeio" was specified. |
| .TP |
| .BI logbufs= value |
| Set the number of in-memory log buffers. Valid numbers |
| range from 2\(en8 inclusive. |
| .sp |
| The default value is 8 buffers. |
| .sp |
| If the memory cost of 8 log buffers is too high on small |
| systems, then it may be reduced at some cost to performance |
| on metadata intensive workloads. The logbsize option below |
| controls the size of each buffer and so is also relevant to |
| this case. |
| .TP |
| .BI logbsize= value |
| Set the size of each in-memory log buffer. The size may be |
| specified in bytes, or in kibibytes (KiB) with a "k" suffix. |
| Valid sizes for version 1 and version 2 logs are 16384 (value=16k) |
| and 32768 (value=32k). Valid sizes for version 2 logs also |
| include 65536 (value=64k), 131072 (value=128k) and 262144 (value=256k). |
| The logbsize must be an integer multiple of the log |
| stripe unit configured at mkfs time. |
| .sp |
| The default value for version 1 logs is 32768, while the |
| default value for version 2 logs is MAX(32768, log_sunit). |
| .TP |
| .BI logdev= "device \fRand " 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. |
| .TP |
| .B noalign |
| Data allocations will not be aligned at stripe unit |
| boundaries. This is only relevant to filesystems created |
| with non-zero data alignment parameters (sunit, swidth) by |
| mkfs. |
| .TP |
| .B 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. |
| .TP |
| .B nouuid |
| Don't check for double mounted file systems using the file |
| system uuid. This is useful to mount LVM snapshot volumes, |
| and often used in combination with "norecovery" for mounting |
| read-only snapshots. |
| .TP |
| .B noquota |
| Forcibly turns off all quota accounting and enforcement |
| within the filesystem. |
| .TP |
| .B uquota/usrquota/uqnoenforce/quota |
| User disk quota accounting enabled, and limits (optionally) |
| enforced. Refer to xfs_quota(8) for further details. |
| .TP |
| .B gquota/grpquota/gqnoenforce |
| Group disk quota accounting enabled and limits (optionally) |
| enforced. Refer to xfs_quota(8) for further details. |
| .TP |
| .B pquota/prjquota/pqnoenforce |
| Project disk quota accounting enabled and limits (optionally) |
| enforced. Refer to xfs_quota(8) for further details. |
| .TP |
| .BI sunit= "value \fRand " 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. These options are only relevant to filesystems |
| that were created with non-zero data alignment parameters. |
| .sp |
| The sunit and swidth parameters specified must be compatible |
| with the existing filesystem alignment characteristics. In |
| general, that means the only valid changes to sunit are |
| increasing it by a power-of-2 multiple. Valid swidth values |
| are any integer multiple of a valid sunit value. |
| .sp |
| Typically the only time these mount options are necessary if |
| after an underlying RAID device has had it's geometry |
| modified, such as adding a new disk to a RAID5 lun and |
| reshaping it. |
| .TP |
| .B swalloc |
| Data allocations will be rounded up to stripe width boundaries |
| when the current end of file is being extended and the file |
| size is larger than the stripe width size. |
| .TP |
| .B wsync |
| When specified, all filesystem namespace operations are |
| executed synchronously. This ensures that when the namespace |
| operation (create, unlink, etc) completes, the change to the |
| namespace is on stable storage. This is useful in HA setups |
| where failover must not result in clients seeing |
| inconsistent namespace presentation during or after a |
| failover event. |
| |
| .SH "THE LOOP DEVICE" |
| One further possible type is a mount via the loop device. For example, |
| the command |
| .RS |
| .sp |
| .B "mount /tmp/disk.img /mnt \-t vfat \-o loop=/dev/loop3" |
| .sp |
| .RE |
| will set up the loop device |
| .I /dev/loop3 |
| to correspond to the file |
| .IR /tmp/disk.img , |
| and then mount this device on |
| .IR /mnt . |
| |
| If no explicit loop device is mentioned |
| (but just an option `\fB\-o loop\fP' is given), then |
| .B mount |
| will try to find some unused loop device and use that, for example |
| .RS |
| .sp |
| .B "mount /tmp/disk.img /mnt \-o loop" |
| .sp |
| .RE |
| The mount command |
| .B automatically |
| creates a loop device from a regular file if a filesystem type is |
| not specified or the filesystem is known for libblkid, for example: |
| .RS |
| .sp |
| .B "mount /tmp/disk.img /mnt" |
| .sp |
| .B "mount \-t ext3 /tmp/disk.img /mnt" |
| .sp |
| .RE |
| This type of mount knows about three options, namely |
| .BR loop ", " offset " and " sizelimit , |
| that are really options to |
| .BR \%losetup (8). |
| (These options can be used in addition to those specific |
| to the filesystem type.) |
| |
| Since Linux 2.6.25 auto-destruction of loop devices is supported, |
| meaning that any loop device allocated by |
| .B mount |
| will be freed by |
| .B umount |
| independently of |
| .IR /etc/mtab . |
| |
| You can also free a loop device by hand, using |
| .BR "losetup \-d " or " umount \-d" . |
| |
| .SH RETURN CODES |
| .B mount |
| has the following return codes (the bits can be ORed): |
| .TP |
| .B 0 |
| success |
| .TP |
| .B 1 |
| incorrect invocation or permissions |
| .TP |
| .B 2 |
| system error (out of memory, cannot fork, no more loop devices) |
| .TP |
| .B 4 |
| internal |
| .B mount |
| bug |
| .TP |
| .B 8 |
| user interrupt |
| .TP |
| .B 16 |
| problems writing or locking /etc/mtab |
| .TP |
| .B 32 |
| mount failure |
| .TP |
| .B 64 |
| some mount succeeded |
| .RE |
| |
| The command \fBmount \-a\fR returns 0 (all succeeded), 32 (all failed), or 64 (some |
| failed, some succeeded). |
| |
| .SH "EXTERNAL HELPERS" |
| The syntax of external mount helpers is: |
| |
| .RS |
| .BI /sbin/mount. suffix |
| .I spec dir |
| .RB [ \-sfnv ] |
| .RB [ \-o |
| .IR options ] |
| .RB [ \-t |
| .IR type \fB. subtype ] |
| .RE |
| |
| where the \fIsuffix\fR is the filesystem type and the \fB\-sfnvo\fR options have |
| the same meaning as the normal mount options. The \fB\-t\fR option is used for |
| filesystems with subtypes support (for example |
| .BR "/sbin/mount.fuse \-t fuse.sshfs" ). |
| |
| The command \fBmount\fR does not pass the mount options |
| .BR unbindable , |
| .BR runbindable , |
| .BR private , |
| .BR rprivate , |
| .BR slave , |
| .BR rslave , |
| .BR shared , |
| .BR rshared , |
| .BR auto , |
| .BR noauto , |
| .BR comment , |
| .BR x-* , |
| .BR loop , |
| .B offset |
| and |
| .B sizelimit |
| to the mount.<suffix> helpers. All other options are used in a |
| comma-separated list as argument to the \fB\-o\fR option. |
| |
| .SH FILES |
| .TP 18n |
| .I /etc/fstab |
| filesystem table |
| .TP |
| .I /etc/mtab |
| table of mounted filesystems |
| .TP |
| .I /etc/mtab\s+3~\s0 |
| lock file |
| .TP |
| .I /etc/mtab.tmp |
| temporary file |
| .TP |
| .I /etc/filesystems |
| a list of filesystem types to try |
| .SH ENVIRONMENT |
| .IP LIBMOUNT_FSTAB=<path> |
| overrides the default location of the fstab file |
| .IP LIBMOUNT_MTAB=<path> |
| overrides the default location of the mtab file |
| .IP LIBMOUNT_DEBUG=0xffff |
| enables debug output |
| .SH "SEE ALSO" |
| .BR mount (2), |
| .BR umount (2), |
| .BR fstab (5), |
| .BR umount (8), |
| .BR swapon (8), |
| .BR findmnt (8), |
| .BR nfs (5), |
| .BR xfs (5), |
| .BR e2label (8), |
| .BR xfs_admin (8), |
| .BR mountd (8), |
| .BR nfsd (8), |
| .BR mke2fs (8), |
| .BR tune2fs (8), |
| .BR losetup (8) |
| .SH BUGS |
| It is possible for a corrupted filesystem to cause a crash. |
| .PP |
| Some Linux filesystems don't support |
| .B "\-o sync and \-o dirsync" |
| (the ext2, ext3, fat and vfat filesystems |
| .I do |
| support synchronous updates (a la BSD) when mounted with the |
| .B sync |
| option). |
| .PP |
| The |
| .B "\-o remount" |
| may not be able to change mount parameters (all |
| .IR ext2fs -specific |
| parameters, except |
| .BR sb , |
| are changeable with a remount, for example, but you can't change |
| .B gid |
| or |
| .B umask |
| for the |
| .IR fatfs ). |
| .PP |
| It is possible that files |
| .I /etc/mtab |
| and |
| .I /proc/mounts |
| don't match on systems with regular mtab file. The first file is based only on |
| the mount command options, but the content of the second file also depends on |
| the kernel and others settings (e.g.\& remote NFS server. In particular case |
| the mount command may reports unreliable information about a NFS mount point |
| and the /proc/mounts file usually contains more reliable information.) This is |
| another reason to replace mtab file with symlink to the |
| .I /proc/mounts |
| file. |
| .PP |
| Checking files on NFS filesystem referenced by file descriptors (i.e.\& the |
| .B fcntl |
| and |
| .B ioctl |
| families of functions) may lead to inconsistent result due to the lack of |
| consistency check in kernel even if noac is used. |
| .PP |
| The |
| .B loop |
| option with the |
| .B offset |
| or |
| .B sizelimit |
| options used may fail when using older kernels if the |
| .B mount |
| command can't confirm that the size of the block device has been configured |
| as requested. This situation can be worked around by using |
| the |
| .B losetup |
| command manually before calling |
| .B mount |
| with the configured loop device. |
| .SH HISTORY |
| A |
| .B mount |
| command existed in Version 5 AT&T UNIX. |
| .SH AUTHORS |
| .nf |
| Karel Zak <kzak@redhat.com> |
| .fi |
| .SH AVAILABILITY |
| The mount command is part of the util-linux package and is available from |
| ftp://ftp.kernel.org/pub/linux/utils/util-linux/. |
| |