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| .TH MOUNT 8 "August 2015" "util-linux" "System Administration" |
| .SH NAME |
| mount \- mount a filesystem |
| .SH SYNOPSIS |
| .B mount |
| .RB [ \-l | \-h | \-V ] |
| .LP |
| .B mount \-a |
| .RB [ \-fFnrsvw ] |
| .RB [ \-t |
| .IR fstype ] |
| .RB [ \-O |
| .IR optlist ] |
| .LP |
| .B mount |
| .RB [ \-fnrsvw ] |
| .RB [ \-o |
| .IR options ] |
| .IR device | dir |
| .LP |
| .B mount |
| .RB [ \-fnrsvw ] |
| .RB [ \-t |
| .IB fstype ] |
| .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 |
| .IR / . |
| 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 filesystem is used to control how data is |
| stored on the device or provided in a virtual way by network or another services. |
| |
| 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 option \fB\-t \fItype\fR is optional. The |
| .B mount |
| command is usually able to detect a filesystem. The root permissions are necessary |
| to mount a filesystem by default. See section "Non-superuser mounts" below for more details. |
| 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 |
| .sp |
| .B mount /dir |
| .sp |
| .RE |
| then \fBmount\fR looks for a mountpoint (and if not found then for a device) in the |
| .I /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 |
| .sp |
| .B mount \-\-target /mountpoint |
| .sp |
| .RE |
| |
| The same filesystem may be mounted more than once, and in some cases (e.g. |
| network filesystems) the same filesystem maybe be mounted on the same |
| mountpoint more times. The mount command does not implement any policy to |
| control this behavior. All behavior is controlled by kernel and it is usually |
| specific to filesystem driver. The exception is \fB\-\-all\fR, in this case |
| already mounted filesystems are ignored (see \fB\-\-all\fR below for more details). |
| |
| .SS Listing the mounts |
| 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 |
| .sp |
| .BR "mount " [ \-l "] [" "\-t \fItype\/\fP" ] |
| .sp |
| .RE |
| The option \fB\-l\fR adds labels to this listing. See below. |
| |
| .SS Indicating the device and filesystem |
| 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). |
| |
| The device name of disk partitions are unstable; hardware reconfiguration, |
| adding or removing a device can cause change in names. This is reason why it's |
| strongly recommended to use filesystem or partition identificators like UUID or |
| LABEL. |
| |
| The command \fBlsblk --fs\fR provides overview of filesystems, LABELs and UUIDs |
| on available block devices. The command \fBblkid -p <device>\fR provides details about |
| a filesystem on the specified device. |
| |
| 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.\& \fBUUID=\fIuuid\fR) rather than |
| .I /dev/disk/by-{label,uuid,partuuid,partlabel} |
| udev symlinks in the |
| .I /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 already mounted' from |
| .B mount |
| can be confusing.) |
| |
| .SS The files /etc/fstab, /etc/mtab and /proc/mounts |
| 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 \fBmount\fR 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. |
| .sp |
| The programs |
| .B mount |
| and |
| .B umount |
| traditionally maintained a list of currently mounted filesystems in the file |
| .IR /etc/mtab . |
| The support for regular classic |
| .IR /etc/mtab |
| is completely disabled in compile time by default, because on current Linux |
| systems it is better to make it a symlink to |
| .I /proc/mounts |
| instead. The regular mtab file maintained in userspace cannot reliably |
| work with namespaces, containers and other advanced Linux features. |
| If the regular mtab support is enabled than it's possible to |
| use the file as well as the symlink. |
| .sp |
| If no arguments are given to |
| .BR mount , |
| the list of mounted filesystems is printed. |
| .sp |
| 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 . |
| This default behaviour is possible to change by command line |
| option \fB\-\-options\-mode\fR. |
| The usual behavior is that the last option wins if there are conflicting |
| ones. |
| .sp |
| 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 |
| This default behaviour is possible to change by command line option |
| \fB\-\-options\-source\-force\fR to always read configuration from fstab. For |
| non-root users |
| .B mount |
| always read fstab configuration. |
| |
| .SS Non-superuser mounts |
| 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 |
| .B "mount /cd" |
| .sp |
| .RE |
| Note that \fBmount\fR is very strict about non-root users and all paths |
| specified on command line are verified before fstab is parsed or a helper |
| program is executed. It's strongly recommended to use a valid mountpoint to |
| specify filesystem, otherwise \fBmount\fR may fail. For example it's bad idea |
| to use NFS or CIFS source on command line. |
| .PP |
| 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. |
| |
| .SS Bind mount operation |
| 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. |
| |
| It is important to understand that "bind" does not to create any second-class |
| or special node in the kernel VFS. The "bind" is just another operation to |
| attach a filesystem. There is nowhere stored information that the filesystem |
| has been attached by "bind" operation. The \fIolddir\fR and \fInewdir\fR are |
| independent and the \fIolddir\fR maybe be umounted. |
| |
| 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. |
| |
| .BR mount (8) |
| since v2.27 allows to change the mount options by passing the |
| relevant options along with |
| .BR \-\-bind . |
| For example: |
| |
| .RS |
| .br |
| .B mount -o bind,ro foo foo |
| .RE |
| |
| This feature is not supported by the Linux kernel; it is implemented in userspace |
| by an additional \fBmount\fR(2) remounting system call. |
| This solution is not atomic. |
| |
| The alternative (classic) way to create a read-only bind mount is to use the remount |
| operation, for example: |
| |
| .RS |
| .br |
| .B mount \-\-bind |
| .I olddir newdir |
| .br |
| .B mount \-o remount,bind,ro |
| .I olddir newdir |
| .RE |
| |
| Note that a read-only 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. |
| |
| It's also possible to change nosuid, nodev, noexec, noatime, nodiratime and |
| relatime VFS entry flags by "remount,bind" operation. The another (for example |
| filesystem specific flags) are silently ignored. It's impossible to change mount |
| options recursively (for example with \fB-o rbind,ro\fR). |
| |
| .BR mount (8) |
| since v2.31 ignores the \fBbind\fR flag from |
| .I /etc/fstab |
| on |
| .B remount operation |
| (if "-o remount" specified on command line). This is necessary to fully control |
| mount options on remount by command line. In the previous versions the bind |
| flag has been always applied and it was impossible to re-define mount options |
| without interaction with the bind semantic. This |
| .BR mount (8) |
| behavior does not affect situations when "remount,bind" is specified in the |
| .I /etc/fstab |
| file. |
| .RE |
| |
| .SS The move operation |
| Move a |
| .B mounted tree |
| to another place (atomically). 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 |
| to see the current propagation flags. |
| |
| .SS Shared subtree operations |
| 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 |
| .I 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) |
| system call, and the flags cannot be mixed with other mount options and operations. |
| |
| Since util-linux 2.23 the \fBmount\fR command allows to do more propagation |
| (topology) changes by one mount(8) call and do it also together with other |
| mount operations. This feature is EXPERIMENTAL. The propagation flags are applied |
| by additional \fBmount\fR(2) system calls when the preceding 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 |
| .B mount \-\-make\-private \-\-make\-unbindable /dev/sda1 /foo |
| .fi |
| .RE |
| |
| is the same as: |
| |
| .RS |
| .nf |
| .B mount /dev/sda1 /foox |
| .B mount \-\-make\-private /foo |
| .B mount \-\-make\-unbindable /foo |
| .fi |
| .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 \fBEXTERNAL HELPERS\fR. |
| .sp |
| Command-line options available for the |
| .B mount |
| command are: |
| .TP |
| .BR \-a , " \-\-all" |
| 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 . |
| The mount command compares filesystem source, target (and fs root for bind |
| mount or btrfs) to detect already mounted filesystems. The kernel table with |
| already mounted filesystems is cached during \fBmount \-\-all\fR. It means |
| that all duplicated fstab entries will be mounted. |
| .sp |
| Note that it is a bad practice to use \fBmount \-a\fR for |
| .I fstab |
| checking. The recommended solution is \fBfindmnt \-\-verify\fR. |
| .TP |
| .BR \-B , " \-\-bind" |
| Remount a subtree somewhere else (so that its contents are available |
| in both places). See above, under \fBBind mounts\fR. |
| .TP |
| .BR \-c , " \-\-no\-canonicalize" |
| 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. |
| .sp |
| Note that \fBmount\fR(8) does not pass this option to the |
| \fB/sbin/mount.\fItype\fR helpers. |
| .TP |
| .BR \-F , " \-\-fork" |
| (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. |
| .TP |
| .BR \-L , " \-\-label " \fIlabel |
| Mount the partition that has the specified |
| .IR label . |
| .TP |
| .BR \-l , " \-\-show\-labels" |
| Add the labels in the mount output. \fBmount\fR must have |
| permission to read the disk device (e.g.\& be set-user-ID 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). |
| .TP |
| .BR \-M , " \-\-move" |
| Move a subtree to some other place. See above, the subsection |
| \fBThe move operation\fR. |
| .TP |
| .BR \-n , " \-\-no\-mtab" |
| Mount without writing in |
| .IR /etc/mtab . |
| This is necessary for example when |
| .I /etc |
| is on a read-only filesystem. |
| .TP |
| .BR \-N , " \-\-namespace " \fIns |
| Perform mount in namespace specified by \fIns\fR. |
| \fIns\fR is either PID of process running in that namespace |
| or special file representing that namespace. |
| .sp |
| .BR mount (8) |
| switches to the namespace when it reads /etc/fstab, writes /etc/mtab (or writes to /run/mount) and calls |
| .BR mount(2) |
| system call, otherwise it runs in the original namespace. It means that the target namespace does not have |
| to contain any libraries or another requirements necessary to execute |
| .BR mount(2) |
| command. |
| .sp |
| See \fBnamespaces\fR(7) for more information. |
| .TP |
| .BR \-O , " \-\-test\-opts " \fIopts |
| 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 |
| .TP |
| .BR \-o , " \-\-options " \fIopts |
| 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 |
| |
| .TP |
| .BR "\-\-options\-mode " \fImode |
| Controls how to combine options from fstab/mtab with options from command line. |
| \fImode\fR can be one of |
| .BR ignore ", " append ", " prepend " or " replace . |
| For example \fBappend\fR means that options from fstab are appended to options from command line. |
| Default value is \fBprepend\fR -- it means command line options are evaluated after fstab options. |
| Note that the last option wins if there are conflicting ones. |
| |
| .TP |
| .BR "\-\-options\-source " \fIsource |
| Source of default options. |
| \fIsource\fR is comma separated list of |
| .BR fstab ", " mtab " and " disable . |
| \fBdisable\fR disables |
| .BR fstab " and " mtab |
| and disables \fB\-\-options\-source\-force\fR. |
| Default value is \fBfstab,mtab\fR. |
| |
| .TP |
| .B \-\-options\-source\-force |
| Use options from fstab/mtab even if both \fIdevice\fR and \fIdir\fR are specified. |
| |
| .TP |
| .BR \-R , " \-\-rbind" |
| Remount a subtree and all possible submounts somewhere else (so that its |
| contents are available in both places). See above, the subsection |
| \fBBind mounts\fR. |
| .TP |
| .BR \-r , " \-\-read\-only" |
| Mount the filesystem read-only. A synonym is |
| .BR "\-o ro" . |
| .sp |
| 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. |
| .TP |
| .B \-s |
| Tolerate sloppy mount options rather than failing. This will ignore mount |
| options not supported by a filesystem type. Not all filesystems support this |
| option. Currently it's supported by the \fBmount.nfs\fR mount helper only. |
| .TP |
| .BI \-\-source " device" |
| 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. |
| .TP |
| .BI \-\-target " directory" |
| 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. |
| .TP |
| .BR \-T , " \-\-fstab " \fIpath |
| 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. |
| .sp |
| 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. |
| .TP |
| .BR \-t , " \-\-types " \fIfstype |
| The argument following the |
| .B \-t |
| is used to indicate the filesystem type. The filesystem types which are |
| currently supported depend on the running kernel. See |
| .I /proc/filesystems |
| and |
| .I /lib/modules/$(uname -r)/kernel/fs |
| for a complete list of the filesystems. The most common are ext2, ext3, ext4, |
| xfs, btrfs, vfat, sysfs, proc, nfs and cifs. |
| .sp |
| 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). |
| |
| 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. |
| .sp |
| 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. |
| .sp |
| More than one type may be specified in a comma-separated |
| list, for option |
| .B \-t |
| as well as in an |
| .I /etc/fstab |
| entry. The list of filesystem types for option |
| .B \-t |
| can be prefixed with |
| .B no |
| to specify the filesystem types on which no action should be taken. |
| The prefix |
| .B no |
| has no effect when specified in an |
| .I /etc/fstab |
| entry. |
| .sp |
| The prefix |
| .B no |
| can be meaningful with the |
| .B \-a |
| option. For example, the command |
| .RS |
| .RS |
| .sp |
| .B "mount \-a \-t nomsdos,smbfs" |
| .sp |
| .RE |
| mounts all filesystems except those of type |
| .I msdos |
| and |
| .IR smbfs . |
| .sp |
| For most types all the |
| .B mount |
| program has to do is issue a simple |
| .BR 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. |
| .RE |
| .TP |
| .BR \-U , " \-\-uuid " \fIuuid |
| Mount the partition that has the specified |
| .IR uuid . |
| .TP |
| .BR \-v , " \-\-verbose" |
| Verbose mode. |
| .TP |
| .BR \-w , " \-\-rw" , " \-\-read\-write" |
| Mount the filesystem read/write. The read-write is kernel default. A synonym is |
| .BR "\-o rw" . |
| |
| Note that specify \fB\-w\fR on command line forces \fBmount\fR command |
| to never try read-only mount on write-protected devices. The default is |
| try read-only if the previous mount syscall with read-write flags failed. |
| .TP |
| .BR \-V , " \-\-version" |
| Display version information and exit. |
| .TP |
| .BR \-h , " \-\-help" |
| Display help text and exit. |
| |
| .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 \fBnoatime\fR feature, so the inode access time is controlled |
| by kernel defaults. See also the descriptions of the \fB\%relatime\fR and |
| .B strictatime |
| 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). This works for all |
| inode types (directories too), so it implies \fB\%nodiratime\fR. |
| .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 |
| .na |
| .BR context=\fIcontext ", " fscontext=\fIcontext ", " defcontext=\fIcontext ", and " \%rootcontext=\fIcontext |
| .ad |
| 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. |
| (This option is ignored when \fBnoatime\fR is set.) |
| .TP |
| .B nodiratime |
| Do not update directory inode access times on this filesystem. |
| (This option is implied when \fBnoatime\fR is set.) |
| .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. |
| .TP |
| .B group |
| Allow an ordinary user to mount the filesystem if one |
| of that user's 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 \fB\%noatime\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 lazytime |
| Only update times (atime, mtime, ctime) on the in-memory version of the file inode. |
| |
| This mount option significantly reduces writes to the inode table for |
| workloads that perform frequent random writes to preallocated files. |
| |
| The on-disk timestamps are updated only when: |
| .sp |
| .RS |
| - the inode needs to be updated for some change unrelated to file timestamps |
| .sp |
| - the application employs |
| .BR fsync (2), |
| .BR syncfs (2), |
| or |
| .BR sync (2) |
| .sp |
| - an undeleted inode is evicted from memory |
| .sp |
| - more than 24 hours have passed since the i-node was written to disk. |
| .RE |
| .sp |
| .TP |
| .B nolazytime |
| Do not use the lazytime feature. |
| .TP |
| .B suid |
| Allow set-user-ID or set-group-ID bits to take |
| effect. |
| .TP |
| .B nosuid |
| Do not allow set-user-ID or set-group-ID 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 user to mount the filesystem if that |
| user 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 operation together with the |
| .B bind |
| flag has special semantic. See above, the subsection \fBBind mounts\fR. |
| |
| The remount functionality follows the standard way the mount command works |
| with options from fstab. This means that \fBmount\fR does not |
| read fstab (or mtab) only when both |
| .I device |
| and |
| .I dir |
| are specified. |
| .sp |
| .in +4 |
| .B "mount \-o remount,rw /dev/foo /dir" |
| .in |
| .sp |
| After this call all old mount options are replaced and arbitrary stuff from |
| fstab (or mtab) is ignored, except the loop= option which is internally |
| generated and maintained by the mount command. |
| .sp |
| .in +4 |
| .B "mount \-o remount,rw /dir" |
| .in |
| .sp |
| After this call, mount reads fstab and merges these options with |
| the options from the command line (\fB\-o\fR). |
| If no mountpoint is found in fstab, then a remount with unspecified source is |
| allowed. |
| .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 the mtab file (or to the private |
| libmount file in /run/mount on systems without a regular mtab) so that this |
| same user 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 user to mount the filesystem. |
| This is the default; it does not imply any other options. |
| .TP |
| .B users |
| Allow any user to mount and to unmount the filesystem, even |
| when some other ordinary user mounted it. |
| 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 as userspace |
| application-specific options. These options are not stored in the user space (e.g. mtab file), |
| nor sent to the mount.\fItype\fR helpers nor to the |
| .BR mount (2) |
| system call. The suggested format is \fBX-\fIappname\fR.\fIoption\fR. |
| .TP |
| .B x-* |
| The same as \fBX-*\fR options, but stored permanently in the user space. It |
| means the options are also available for umount or another operations. Note |
| that maintain mount options in user space is tricky, because it's necessary use |
| libmount based tools and there is no guarantee that the options will be always |
| available (for example after a move mount operation or in unshared namespace). |
| |
| Note that before util-linux v2.30 the x-* options have not been maintained by |
| libmount and stored in user space (functionality was the same as have X-* now), |
| but due to growing number of use-cases (in initrd, systemd etc.) the |
| functionality have been extended to keep existing fstab configurations usable |
| without a change. |
| .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. The option is also supported as x-mount.mkdir, this notation |
| is deprecated for mount.mkdir since v2.30. |
| |
| .SH "FILESYSTEM-SPECIFIC MOUNT OPTIONS" |
| You should consult the respective man page for the filesystem first. |
| If you want to know what options the ext4 filesystem supports, then check the |
| .BR ext4 (5) |
| man page. |
| If that doesn't exist, you can also check the corresponding mount page like |
| .BR mount.cifs (8). |
| Note that you might have to install the respective userland tools. |
| .sp |
| The following options apply only to certain filesystems. |
| We sort them by filesystem. They all follow the |
| .B \-o |
| flag. |
| .sp |
| What options are supported depends a bit on the running kernel. |
| More info may be found in the kernel source subdirectory |
| .IR Documentation/filesystems . |
| |
| .SS "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 . |
| |
| .SS "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 .) |
| |
| .SS "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. |
| |
| .SS "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. |
| |
| .SS "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. |
| .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. |
| .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 pickyness 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 |
| This option is obsolete and may fail or being ignored. |
| .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 |
| .B dos1xfloppy |
| If set, use a fallback default BIOS Parameter Block configuration, determined |
| by backing device size. These static parameters match defaults assumed by DOS |
| 1.x for 160 kiB, 180 kiB, 320 kiB, and 360 kiB floppies and floppy images. |
| .TP |
| .BR errors= { panic | continue | remount-ro } |
| Specify FAT behavior on critical errors: panic, continue without doing |
| anything, or remount the partition in read-only mode (default behavior). |
| .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 |
| .BR nfs= { stale_rw | nostale_ro } |
| Enable this only if you want to export the FAT filesystem over NFS. |
| |
| .BR stale_rw : |
| This option maintains an index (cache) of directory inodes which is used by the |
| nfs-related code to improve look-ups. Full file operations (read/write) over |
| NFS are supported but with cache eviction at NFS server, this could result in |
| spurious |
| .B ESTALE |
| errors. |
| |
| .BR nostale_ro : |
| This option bases the inode number and file handle |
| on the on-disk location of a file in the FAT directory entry. |
| This ensures that |
| .B ESTALE |
| will not be returned after a file is |
| evicted from the inode cache. However, it means that operations |
| such as rename, create and unlink could cause file handles that |
| previously pointed at one file to point at a different file, |
| potentially causing data corruption. For this reason, this |
| option also mounts the filesystem readonly. |
| |
| To maintain backward compatibility, '-o nfs' is also accepted, |
| defaulting to |
| .BR stale_rw . |
| .TP |
| .B 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 |
| .BI time_offset= minutes |
| Set offset for conversion of timestamps from local time used by FAT to UTC. |
| I.e., |
| .I minutes |
| will be subtracted from each timestamp to convert it to UTC used |
| internally by Linux. This is useful when the time zone set in the kernel via |
| .BR settimeofday (2) |
| is not the time zone used by the filesystem. Note |
| that this option still does not provide correct time stamps in all cases in |
| presence of DST - time stamps in a different DST setting will be off by one |
| hour. |
| .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 rodir |
| FAT has the ATTR_RO (read-only) attribute. On Windows, the ATTR_RO of the |
| directory will just be ignored, and is used only by applications as a flag |
| (e.g.\& it's set for the customized folder). |
| |
| If you want to use ATTR_RO as read-only flag even for the directory, set this |
| option. |
| .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. |
| |
| .SS "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. |
| |
| .SS "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 |
| .BI conv= mode |
| This option is obsolete and may fail or being ignored. |
| .TP |
| .B nocheck |
| Do not abort mounting when certain consistency checks fail. |
| |
| .SS "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.) |
| Octal mode values require 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 |
| .BI conv= mode |
| This option is obsolete and may fail or being ignored. |
| .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. |
| .TP |
| .BI sbsector= xxx |
| Session begins from sector xxx. |
| .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. |
| |
| .SS "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. |
| |
| .SS "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. |
| |
| .SS "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. |
| |
| .SS "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. |
| .TP |
| .BI nls= name |
| New name for the option earlier called |
| .IR iocharset . |
| .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. |
| |
| .SS "Mount options for overlay" |
| Since Linux 3.18 the overlay pseudo filesystem implements a union mount for |
| other filesystems. |
| |
| An overlay filesystem combines two filesystems - an \fBupper\fR filesystem and |
| a \fBlower\fR filesystem. When a name exists in both filesystems, the object |
| in the upper filesystem is visible while the object in the lower filesystem is |
| either hidden or, in the case of directories, merged with the upper object. |
| |
| The lower filesystem can be any filesystem supported by Linux and does not need |
| to be writable. The lower filesystem can even be another overlayfs. The upper |
| filesystem will normally be writable and if it is it must support the creation |
| of trusted.* extended attributes, and must provide a valid d_type in readdir |
| responses, so NFS is not suitable. |
| |
| A read-only overlay of two read-only filesystems may use any filesystem type. |
| The options \fBlowerdir\fR and \fBupperdir\fR are combined into a merged |
| directory by using: |
| |
| .RS |
| .br |
| .nf |
| .B "mount \-t overlay overlay \e" |
| .B " \-olowerdir=/lower,upperdir=/upper,workdir=/work /merged" |
| .fi |
| .br |
| .RE |
| |
| .TP |
| .BI lowerdir= directory |
| Any filesystem, does not need to be on a writable filesystem. |
| .TP |
| .BI upperdir= directory |
| The upperdir is normally on a writable filesystem. |
| .TP |
| .BI workdir= directory |
| The workdir needs to be an empty directory on the same filesystem as upperdir. |
| |
| .SS "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. |
| |
| .SS "Mount options for ubifs" |
| UBIFS is a flash filesystem which works on top of UBI volumes. Note that |
| \fBatime\fR 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. |
| |
| .SS "Mount options for udf" |
| UDF is the "Universal Disk Format" filesystem defined by OSTA, the Optical |
| Storage Technology Association, and is often used for DVD-ROM, frequently |
| in the form of a hybrid UDF/ISO-9660 filesystem. It is, however, |
| perfectly usable by itself on disk drives, flash drives and other block devices. |
| See also |
| .IR iso9660 . |
| .TP |
| .B uid= |
| Make all files in the filesystem belong to the given user. |
| uid=forget can be specified independently of (or usually in |
| addition to) uid=<user> and results in UDF |
| not storing uids to the media. In fact the recorded uid |
| is the 32-bit overflow uid -1 as defined by the UDF standard. |
| The value is given as either <user> which is a valid user name or the corresponding |
| decimal user id, or the special string "forget". |
| .TP |
| .B gid= |
| Make all files in the filesystem belong to the given group. |
| gid=forget can be specified independently of (or usually in |
| addition to) gid=<group> and results in UDF |
| not storing gids to the media. In fact the recorded gid |
| is the 32-bit overflow gid -1 as defined by the UDF standard. |
| The value is given as either <group> which is a valid group name or the corresponding |
| decimal group id, or the special string "forget". |
| .TP |
| .B umask= |
| Mask out the given permissions from all inodes read from the filesystem. |
| The value is given in octal. |
| .TP |
| .B mode= |
| If mode= is set the permissions of all non-directory inodes read from the |
| filesystem will be set to the given mode. The value is given in octal. |
| .TP |
| .B dmode= |
| If dmode= is set the permissions of all directory inodes read from the |
| filesystem will be set to the given dmode. The value is given in octal. |
| .TP |
| .B bs= |
| Set the block size. Default value prior to kernel version 2.6.30 was |
| 2048. Since 2.6.30 and prior to 4.11 it was logical device block size with |
| fallback to 2048. Since 4.11 it is logical block size with fallback to |
| any valid block size between logical device block size and 4096. |
| |
| For other details see the \fBmkudffs\fP(8) 2.0+ manpage, sections |
| \fBCOMPATIBILITY\fP and \fBBLOCK SIZE\fP. |
| .TP |
| .B unhide |
| Show otherwise hidden files. |
| .TP |
| .B undelete |
| Show deleted files in lists. |
| .TP |
| .B adinicb |
| Embed data in the inode. (default) |
| .TP |
| .B noadinicb |
| Don't embed data in the inode. |
| .TP |
| .B shortad |
| Use short UDF address descriptors. |
| .TP |
| .B longad |
| Use long UDF address descriptors. (default) |
| .TP |
| .B nostrict |
| Unset strict conformance. |
| .TP |
| .B iocharset= |
| Set the NLS character set. This requires kernel compiled with CONFIG_UDF_NLS option. |
| .TP |
| .B utf8 |
| Set the UTF-8 character set. |
| .SS Mount options for debugging and disaster recovery |
| .TP |
| .B novrs |
| Ignore the Volume Recognition Sequence and attempt to mount anyway. |
| .TP |
| .B session= |
| Select the session number for multi-session recorded optical media. (default= last session) |
| .TP |
| .B anchor= |
| Override standard anchor location. (default= 256) |
| .TP |
| .B lastblock= |
| Set the last block of the filesystem. |
| .SS Unused historical mount options that may be encountered and should be removed |
| .TP |
| .B uid=ignore |
| Ignored, use uid=<user> instead. |
| .TP |
| .B gid=ignore |
| Ignored, use gid=<group> instead. |
| .TP |
| .B volume= |
| Unimplemented and ignored. |
| .TP |
| .B partition= |
| Unimplemented and ignored. |
| .TP |
| .B fileset= |
| Unimplemented and ignored. |
| .TP |
| .B rootdir= |
| Unimplemented and ignored. |
| |
| .SS "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 |
| |
| .SS "Mount options for umsdos" |
| See mount options for msdos. |
| The |
| .B dotsOK |
| option is explicitly killed by |
| .IR umsdos . |
| |
| .SS "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 |
| |
| .SS "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 "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" . |
| |
| Since util-linux v2.29 mount command re-uses the loop device rather than |
| initialize a new device if the same backing file is already used for some loop |
| device with the same offset and sizelimit. This is necessary to avoid |
| a filesystem corruption. |
| |
| .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: |
| .sp |
| .in +4 |
| .BI /sbin/mount. suffix |
| .I spec dir |
| .RB [ \-sfnv ] |
| .RB [ \-N |
| .IR namespace ] |
| .RB [ \-o |
| .IR options ] |
| .RB [ \-t |
| .IR type \fB. subtype ] |
| .in |
| .sp |
| where the \fIsuffix\fR is the filesystem type and the \fB\-sfnvoN\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 |
| See also "\fBThe files /etc/fstab, /etc/mtab and /proc/mounts\fR" section above. |
| .TP 18n |
| .I /etc/fstab |
| filesystem table |
| .TP |
| .I /run/mount |
| libmount private runtime directory |
| .TP |
| .I /etc/mtab |
| table of mounted filesystems or symlink to /proc/mounts |
| .TP |
| .I /etc/mtab\s+3~\s0 |
| lock file (unused on systems with mtab symlink) |
| .TP |
| .I /etc/mtab.tmp |
| temporary file (unused on systems with mtab symlink) |
| .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 (ignored for suid) |
| .IP LIBMOUNT_MTAB=<path> |
| overrides the default location of the mtab file (ignored for suid) |
| .IP LIBMOUNT_DEBUG=all |
| enables libmount debug output |
| .IP LIBBLKID_DEBUG=all |
| enables libblkid debug output |
| .IP LOOPDEV_DEBUG=all |
| enables loop device setup debug output |
| .SH "SEE ALSO" |
| .na |
| .BR mount (2), |
| .BR umount (2), |
| .BR umount (8), |
| .BR fstab (5), |
| .BR nfs (5), |
| .BR xfs (5), |
| .BR e2label (8), |
| .BR findmnt (8), |
| .BR losetup (8), |
| .BR mke2fs (8), |
| .BR mountd (8), |
| .BR nfsd (8), |
| .BR swapon (8), |
| .BR tune2fs (8), |
| .BR xfs_admin (8) |
| .ad |
| .SH BUGS |
| It is possible for a corrupted filesystem to cause a crash. |
| .PP |
| Some Linux filesystems don't support |
| .BR "\-o sync " nor " \-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 the files |
| .I /etc/mtab |
| and |
| .I /proc/mounts |
| don't match on systems with a 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.\& on a remote NFS server -- in certain cases |
| the mount command may report unreliable information about an NFS mount point |
| and the /proc/mounts file usually contains more reliable information.) This is |
| another reason to replace the mtab file with a symlink to the |
| .I /proc/mounts |
| file. |
| .PP |
| Checking files on NFS filesystems referenced by file descriptors (i.e.\& the |
| .B fcntl |
| and |
| .B ioctl |
| families of functions) may lead to inconsistent results due to the lack of |
| a consistency check in the 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 |
| https://www.kernel.org/pub/linux/utils/util-linux/. |