MOUNT(8)                NetBSD System Manager's Manual                MOUNT(8)

NAME
     mount -- mount file systems

SYNOPSIS
     mount [-Aadfruvw] [-t type]
     mount [-dfruvw] {special | node}
     mount [-dfruvw] [-o options] [-t type] special node

DESCRIPTION
     The mount command invokes a file system-specific program to prepare and
     graft the special device on to the file system tree at the point node, or
     to update options for an already-mounted file system.

     The node argument is always interpreted as a directory in the name space
     of currently mounted file systems.  The special argument is interpreted
     in different ways by the programs that handle different file system
     types; for example, mount_ffs(8) interprets it as a device node,
     mount_null(8) interprets it as a directory name, and mount_nfs(8) inter-
     prets it as reference to a remote host and a directory on that host.

     The system maintains a list of currently mounted file systems.  This list
     is printed if mount is invoked with no arguments, and with no options
     that require some other behaviour.

     If exactly one of special or node is provided, then the missing informa-
     tion (including the file system type) is taken from the fstab(5) file.
     The provided argument is looked up first in the ``fs_file'', then in the
     ``fs_spec'' column.  If the matching entry in fstab(5) has the string
     ``from_mount'' as its ``fs_spec'' field, the device or remote file system
     already mounted at the location specified by ``fs_spec'' will be used.

     If both special and node are provided, then fstab(5) is not used.  In
     this case, if the file system type is not specified via the -t flag, then
     mount may determine the type from the disk label (see disklabel(8)).  In
     addition, if special contains a colon (`:') or at sign (`@'), then the
     nfs type is inferred, but this behaviour is deprecated, and will be
     removed in a future version of mount.

     In NetBSD, a file system can only be mounted by an ordinary user who owns
     the point node and has access to the special device (at least read per-
     missions).  Also, the vfs.generic.usermount sysctl(3) must be set to 1 to
     permit file system mounting by ordinary users, see sysctl(8).  Finally,
     the flags nosuid and nodev must be given for non-superuser mounts.

     The options are as follows:

     -A      Causes mount to try to mount all of the file systems listed in
             the fstab(5) file except those for which the ``noauto'' option is
             specified.

     -a      Similar to the -A flag, except that if a file system (other than
             the root file system) appears to be already mounted, mount will
             not try to mount it again.  mount assumes that a file system is
             already mounted if a file system with the same type is mounted on
             the given mount point.  More stringent checks are not possible
             because some file system types report strange values for the
             mounted-from device for mounted file systems.

     -d      Causes everything to be done except for the invocation of the
             file system-specific program.  This option is useful in conjunc-
             tion with the -v flag to determine what the mount command is try-
             ing to do.

     -f      Forces the revocation of write access when trying to downgrade a
             file system mount status from read-write to read-only.

     -o      Options are specified with a -o flag followed by a comma sepa-
             rated string of options.  The following options are available:

             async       All I/O to the file system should be done asyn-
                         chronously.  In the event of a crash, it is
                         impossible for the system to verify the integrity of
                         data on a file system mounted with this option.  You
                         should only use this option if you have an applica-
                         tion-specific data recovery mechanism, or are willing
                         to recreate the file system from scratch.

             noasync     Clear async mode.

             force       The same as -f; forces the revocation of write access
                         when trying to downgrade a file system mount status
                         from read-write to read-only.

             getargs     Retrieves the file system specific mount arguments
                         for the given mounted file system and prints them.

             hidden      By setting the MNT_IGNORE flag, causes the mount
                         point to be excluded from the list of file systems
                         shown by default with df(1).

             noatime     Never update the access time field for files.  This
                         option is useful for optimizing read performance on
                         file systems that are used as news spools.

             noauto      This file system should be skipped when mount is run
                         with the -a flag.

             nocoredump  Do not allow programs to create crash dumps (core
                         files) on the file system.  This option can be used
                         to help protect sensitive data by keeping core files
                         (which may contain sensitive data) from being created
                         on insecure file systems.  Only core files that would
                         be created by program crashes are prevented by use of
                         this flag; the behavior of savecore(8) is not
                         affected.

             nodev       Do not interpret character or block special devices
                         on the file system.  This option is useful for a
                         server that has file systems containing special
                         devices for architectures other than its own.

             nodevmtime  Do not update modification times on device special
                         files.  This option is useful on laptops or other
                         systems that perform power management.

             noexec      Do not allow execution of any binaries on the mounted
                         file system.  This option is useful for a server that
                         has file systems containing binaries for architec-
                         tures other than its own.

             nosuid      Do not allow set-user-identifier or set-group-identi-
                         fier bits to take effect.

             port        (NFS only) Use the specified NFS port.

             rdonly      The same as -r; mount the file system read-only (even
                         the super-user may not write it).

             reload      Reload all incore data for a file system.  This is
                         used mainly after running fsck(8) on the root file
                         system and finding things to fix.  The file system
                         must be mounted read-only.  All cached meta-data are
                         invalidated, superblock and summary information is
                         re-read from disk, all cached inactive vnodes and
                         file data are invalidated and all inode data are re-
                         read for all active vnodes.

             rump        Instead of running mount_type to mount the file sys-
                         tem, run rump_type.  This uses a userspace server to
                         mount the file system and does not require kernel
                         support for the specific file system type.  See the
                         -t flag and respective rump_type manual page for more
                         information.

             softdep     (FFS only) Mount the file system using soft dependen-
                         cies.  This means that metadata will not be written
                         immediately, but is written in an ordered fashion to
                         keep the on-disk state of the file system consistent.
                         This results in significant speedups for file cre-
                         ate/delete operations.  This option will be ignored
                         when using the -u flag and a file system is already
                         mounted read/write.  This option has gone through
                         moderate to heavy testing, but should still be used
                         with care.  A file system mounted with softdep can
                         not be mounted with async or log.  It requires the
                         SOFTDEP option to be enabled in the running kernel.

             log         (FFS only with UFS2 superblock layout) Mount the file
                         system with wapbl(4) meta-data journaling.  It pro-
                         vides rapid file system consistency checking after a
                         system outage.  It also provides better general-use
                         performance over regular FFS similar to softdep.
                         This option has gone through moderate testing, but
                         still should be considered experimental.  A file sys-
                         tem mounted with log can not be mounted with async or
                         softdep.  It requires the WAPBL option to be enabled
                         in the running kernel.  See wapbl(4) for more infor-
                         mation.

             symperm     Recognize permission of symbolic link when reading or
                         traversing link.

             sync        All I/O to the file system should be done syn-
                         chronously.  This is not equivalent to the normal
                         mode in which only metadata is written synchronously.

             nosync      Clear sync mode.

             union       Causes the namespace at the mount point to appear as
                         the union of the mounted file system root and the
                         existing directory.  Lookups will be done in the
                         mounted file system first.  If those operations fail
                         due to a non-existent file the underlying directory
                         is then accessed.  All creates are done in the
                         mounted file system, except for the fdesc file sys-
                         tem.

             update      The same as -u; indicate that the status of an
                         already mounted file system should be changed.

             Any additional options specific to a given file system type (see
             the -t option) may be passed as a comma separated list; these
             options are distinguished by a leading ``-'' (dash).  Options
             that take a value are specified using the syntax -option=value.
             For example, the mount command:

                   mount -t mfs -o nosuid,-N,-s=32m swap /tmp

             causes mount to execute the equivalent of:

                   /sbin/mount_mfs -o nosuid -N -s 32m swap /tmp

     -r      The file system is to be mounted read-only.  Mount the file sys-
             tem read-only (even the super-user may not write it).  The same
             as the ``rdonly'' argument to the -o option.

     -t type
             The argument following the -t is used to indicate the file system
             type.  The type ffs is the default.  The -t option can be used to
             indicate that the actions should only be taken on file systems of
             the specified type.  More than one type may be specified in a
             comma separated list.  The list of file system types can be pre-
             fixed with ``no'' to specify the file system types for which
             action should not be taken.  For example, the mount command:

                   mount -a -t nonfs,mfs

             mounts all file systems except those of type NFS and MFS.

             mount will attempt to execute a program in /sbin/mount_XXX where
             XXX is replaced by the type name.  For example, nfs file systems
             are mounted by the program /sbin/mount_nfs.

     -u      The -u flag indicates that the status of an already mounted file
             system should be changed.  Any of the options discussed above
             (the -o option) may be changed; also a file system can be changed
             from read-only to read-write or vice versa.  An attempt to change
             from read-write to read-only will fail if any files on the file
             system are currently open for writing unless the -f flag is also
             specified.  The set of options is determined by first extracting
             the options for the file system from the fstab(5) file, then
             applying any options specified by the -o argument, and finally
             applying the -r or -w option.

     -v      Verbose mode.  If this flag is specified more than once, then the
             file system-specific mount arguments are printed for the given
             mounted file system.

     -w      The file system object is to be read and write.

     The options specific to the various file system types are described in
     the manual pages for those file systems' mount_XXX commands.  For
     instance the options specific to Berkeley Fast File System (FFS) are
     described in the mount_ffs(8) manual page.

     The particular type of file system in each partition of a disk can be
     found by examining the disk label with the disklabel(8) command.

FILES
     /etc/fstab  file system table

EXAMPLES
     Some useful examples:

           CD-ROM
                   mount -t cd9660 -r /dev/cd0a /cdrom

           MS-DOS
                   mount -t msdos /dev/fd0a /floppy

           NFS
                   mount -t nfs nfs-server-host:/directory/path /mount-point

           MFS (32 megabyte)
                   mount -t mfs -o nosuid,-s=32m swap /tmp

     The ``noauto'' directive in /etc/fstab can be used to make it easy to
     manually mount and unmount removable media using just the mountpoint
     filename, with an entry like this:

           /dev/cd0a /cdrom cd9660 ro,noauto 0 0

     That would allow a simple command like "mount /cdrom" or "umount /cdrom"
     for media using the ISO-9660 file system format in the first CD-ROM
     drive.

DIAGNOSTICS
     The error ``Operation not supported by device'' indicates that the mount
     for the specified file-system type cannot be completed because the kernel
     lacks support for the said file-system.  See options(4).

     The error ``Operation not permitted'' may indicate that the mount options
     include privileged options and/or don't include options that exclude
     privileged options.  One should try using at least ``nodev'' and
     ``nosuid'' in such cases:

           mount -t cd9660 -o nodev,nosuid /dev/cd0a /mnt

SEE ALSO
     df(1), mount(2), options(4), wapbl(4), fstab(5), disklabel(8), fsck(8),
     mount_ados(8), mount_cd9660(8), mount_ext2fs(8), mount_fdesc(8),
     mount_ffs(8), mount_filecore(8), mount_kernfs(8), mount_lfs(8),
     mount_mfs(8), mount_msdos(8), mount_nfs(8), mount_ntfs(8), mount_null(8),
     mount_overlay(8), mount_portal(8), mount_procfs(8), mount_tmpfs(8),
     mount_udf(8), mount_umap(8), mount_union(8), rump_cd9660(8), rump_efs(8),
     rump_ext2fs(8), rump_ffs(8), rump_hfs(8), rump_lfs(8), rump_msdos(8),
     rump_nfs(8), rump_ntfs(8), rump_sysvbfs(8), rump_tmpfs(8), rump_udf(8),
     umount(8)

HISTORY
     A mount command appeared in Version 6 AT&T UNIX.

NetBSD 5.0.1                   January 20, 2009                   NetBSD 5.0.1

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