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

     mount -- mount file systems

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

     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 al-
     ready 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 re-
     moved in a	future version of mount.

     In	NetBSD,	the file-system	mounting policy	is dictated by the running se-
     curity models.  The default security model	may allow unprivileged mount-
     ing; 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

     -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.

	     extattr	 Enable	extended attributes, if	the filesystem sup-
			 ports them and	does not enable	them by	default.  Cur-
			 rently	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 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 af-

	     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 de-
			 vices 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

	     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
			 outage.  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 up-
			 date 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 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 ex-
			 isting	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-

	     update	 The same as -u; indicate that the status of an	al-
			 ready 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 op-
	     tions 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 ap-
	     plying any	options	specified by the -o argument, and finally ap-
	     plying 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 in-
     stance the	options	specific to Berkeley Fast File System (FFS) are	de-
     scribed 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.

     /etc/fstab	 file system table

     Some useful examples:

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

		   mount -t msdos /dev/fd0a /floppy

		   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 manu-
     ally mount	and unmount removable media using just the mountpoint file-
     name, 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

     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

     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)

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

BSD				 July 22, 2011				   BSD


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