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NetBSD 6.1.5 - man page for mount (netbsd section 8)

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MOUNT(8)			   BSD 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) interprets 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 information (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, the file-system mounting policy is dictated by the running security models.  The
     default security model may allow unprivileged mounting; see secmodel_suser(9) for details.

     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 sys-
	     tem) 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 conjunction with the -v flag to determine what
	     the mount command is trying 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 separated string of
	     options.  The following options are available:

	     async	 All I/O to the file system should be done asynchronously.  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 application-specific data recovery mechanism,
			 or are willing to recreate the file system from scratch.

	     noasync	 Clear async mode.

	     extattr	 Enable extended attributes, if the filesystem supports them and does not
			 enable them by default.  Currently this is only the case for UFS1.

	     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 keep-
			 ing 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 spe-
			 cial 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 architectures other than its own.

	     nosuid	 Do not allow set-user-identifier or set-group-identifier 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 invali-
			 dated, 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 system, 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.

	     log	 (FFS only) Mount the file system with wapbl(4) meta-data journaling,
			 also known simply as logging.	It provides rapid metadata updates and
			 eliminates the need to check file system consistency after a system out-
			 age.  A file system mounted with log can not be mounted with async.  It
			 requires the WAPBL option to be enabled in the running kernel.  See
			 wapbl(4) for more information.  This option requires the ``UFS2'' (level
			 4) superblock layout, which is the default for newly created FFSv1 and
			 FFSv2 file systems.  To update an old file system with an earlier
			 superblock format, use the -c option of fsck_ffs(8).

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

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

	     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 cre-
			 ates 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 sys-
			 tem 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 system 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 prefixed
	     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-spe-
	     cific 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-sys-
     tem.  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_smbfs(8), rump_sysvbfs(8), rump_tmpfs(8), rump_udf(8), umount(8)

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

BSD					  July 22, 2011 				      BSD
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