mount

mount a file system
All files accessible in a Unix system are arranged in one big tree, the file hierarchy, rooted at /. These files can be spread out over several devices. The mount command serves to attach the file system found on some device to the big file tree.
The system maintains a list of currently mounted file systems. If no arguments are given to mount, this list is printed.

SYNTAX
      mount [-adfruvw] [-t ufs | lfs | external_type]

      mount [-dfruvw] special | node

      mount [-dfruvw] [-o options] [-t ufs | lfs | external_type] special node

OPTIONS

  -a	All the filesystems described in fstab(5) are mounted.  Excep-
	tions are those marked as ``noauto'' or are excluded by the -t
        flag (see below).
     

  -d	Causes everything to be done except for the actual system call.
	This option is useful in conjunction with the -v flag to deter-
	mine what the mount command is trying to do.

  -f	Forces the revocation of write access when trying to downgrade a
	filesystem 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 asynchronously.
		     This can be somewhat dangerous with respect to losing
		     data when faced with system crashes and power outages.
		     This is also the default.	It can be avoided with the
		     noasync option.

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

	     noasync
		     This filesystem should not force all I/O to be written
		     asynchronously.

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

	     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 architec-
		     tures other than its own.

	     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.

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

	     sync    All I/O to the file system should be done synchronously.

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

	     union   Causes the namespace at the mount point to appear as the
		     union of the mounted filesystem root and the existing
		     directory.	 Lookups will be done in the mounted filesys-
		     tem first.	 If those operations fail due to a non-exis-
		     tent file the underlying directory is then accessed.  All
		     creates are done in the mounted filesystem.

	     Any additional options specific to a filesystem type that is not
	     one of the internally known types (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 speci-
	     fied using the syntax -option=value.  For example, the mount com-
	     mand:
		   mount -t hfs -o nosuid,-w,-m=755 /dev/disk2s9 /tmp

	     causes mount to execute the equivalent of:

		   /sbin/mount_hfs -o nosuid -w -m 755 /dev/disk2s9 /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 ufs | lfs | external type

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

	   mount -a -t nonfs,hfs

	mounts all filesystems except those of type NFS and HFS.

	If the type is not one of the internally known types, mount will
	attempt to execute a program in /sbin/mount_XXX where XXX is
	replaced by the type name.	 For example, nfs filesystems 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
	filesystem 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 table,
	then applying any options specified by the -o argument, and
	finally applying the -r or -w option.

  -v	Verbose mode.

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

	The options specific to NFS filesystems are described in the
	mount_nfs(8) manual page.

The mount command calls the mount(2) system call to prepare and graft a special device or the remote node (rhost:path) on to the file system tree at the point node. If either special or node are not provided, the appropriate information is taken from the fstab(5) file.

"The Ten Commandments and the Sermon on the Mount contain my religion" - John Adams

Related commands:

bless - Set volume bootability and startup disk options.
diskutil - Disk utilities - Format, Verify, Repair
df - Display free disk space
hdiutil - manipulate disk images
umount - detach/unmount a device

Equivalent BASH command:

mount - mount a file system