Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
MOUNT(2)		  FreeBSD System Calls Manual		      MOUNT(2)

NAME
     mount, unmount -- mount or	dismount a file	system

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/param.h>
     #include <sys/mount.h>

     int
     mount(const char *type, const char	*dir, int flags, void *data);

     int
     unmount(const char	*dir, int flags);

DESCRIPTION
     The mount() function grafts a file	system object onto the system file
     tree at the point dir.  The argument data describes the file system
     object to be mounted.  The	argument type tells the	kernel how to inter-
     pret data (See type below).  The contents of the file system become
     available through the new mount point dir.	 Any files in dir at the time
     of	a successful mount are swept under the carpet so to speak, and are
     unavailable until the file	system is unmounted.

     The following flags may be	specified to suppress default semantics	which
     affect file system	access.

     MNT_RDONLY	      The file system should be	treated	as read-only; Even the
		      super-user may not write on it.  Specifying MNT_UPDATE
		      without this option will upgrade a read-only file	system
		      to read/write.

     MNT_NOEXEC	      Do not allow files to be executed	from the file system.

     MNT_NOSUID	      Do not honor setuid or setgid bits on files when execut-
		      ing them.

     MNT_NOATIME      Disable update of	file access times.

     MNT_NODEV	      Do not interpret special files on	the file system.

     MNT_SUIDDIR      Directories with the SUID	bit set	chown new files	to
		      their own	owner.

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

     MNT_ASYNC	      All I/O to the file system should	be done	asyn-
		      chronously.

     MNT_FORCE	      Force a read-write mount even if the file	system appears
		      to be unclean.  Dangerous.

     MNT_NOCLUSTERR   Disable read clustering.

     MNT_NOCLUSTERW   Disable write clustering.

     The flag MNT_UPDATE indicates that	the mount command is being applied to
     an	already	mounted	file system.  This allows the mount flags to be
     changed without requiring that the	file system be unmounted and
     remounted.	 Some file systems may not allow all flags to be changed.  For
     example, many file	systems	will not allow a change	from read-write	to
     read-only.

     The flag MNT_RELOAD causes	the vfs	subsystem to update its	data struc-
     tures pertaining to the specified already mounted file system.

     The type argument names the file system.  The types of file systems known
     to	the system can be obtained with	lsvfs(1).

     Data is a pointer to a structure that contains the	type specific argu-
     ments to mount.  The format for these argument structures is described in
     the manual	page for each file system.  By convention file system manual
     pages are named by	prefixing ``mount_'' to	the name of the	file system as
     returned by lsvfs(1).  Thus the NFS file system is	described by the
     mount_nfs(8) manual page.

     The unmount() function call disassociates the file	system from the	speci-
     fied mount	point dir.

     The flags argument	may specify MNT_FORCE to specify that the file system
     should be forcibly	unmounted or made read-only (if	MNT_UPDATE and
     MNT_RDONLY	are also specified) even if files are still active.  Active
     special devices continue to work, but any further accesses	to any other
     active files result in errors even	if the file system is later remounted.

     The MNT_SUIDDIR option requires the SUIDDIR option	to have	been compiled
     into the kernel to	have any effect.  See the mount(8) and chmod(2)	pages
     for more information.

RETURN VALUES
     Upon successful completion, the value 0 is	returned; otherwise the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     The mount() function will fail when one of	the following occurs:

     [EPERM]		The caller is not the super-user.

     [ENAMETOOLONG]	A component of a pathname exceeded 255 characters, or
			the entire length of a path name exceeded 1023 charac-
			ters.

     [ELOOP]		Too many symbolic links	were encountered in translat-
			ing a pathname.

     [ENOENT]		A component of dir does	not exist.

     [ENOTDIR]		A component of name is not a directory,	or a path pre-
			fix of special is not a	directory.

     [EBUSY]		Another	process	currently holds	a reference to dir.

     [EFAULT]		Dir points outside the process's allocated address
			space.

     The following errors can occur for	a ufs file system mount:

     [ENODEV]		A component of ufs_args	fspec does not exist.

     [ENOTBLK]		Fspec is not a block device.

     [ENXIO]		The major device number	of fspec is out	of range (this
			indicates no device driver exists for the associated
			hardware).

     [EBUSY]		Fspec is already mounted.

     [EMFILE]		No space remains in the	mount table.

     [EINVAL]		The super block	for the	file system had	a bad magic
			number or an out of range block	size.

     [ENOMEM]		Not enough memory was available	to read	the cylinder
			group information for the file system.

     [EIO]		An I/O error occurred while reading the	super block or
			cylinder group information.

     [EFAULT]		Fspec points outside the process's allocated address
			space.

     The following errors can occur for	a nfs file system mount:

     [ETIMEDOUT]	Nfs timed out trying to	contact	the server.

     [EFAULT]		Some part of the information described by nfs_args
			points outside the process's allocated address space.

     The unmount() function may	fail with one of the following errors:

     [EPERM]		The caller is not the super-user.

     [ENOTDIR]		A component of the path	is not a directory.

     [ENAMETOOLONG]	A component of a pathname exceeded 255 characters, or
			an entire path name exceeded 1023 characters.

     [ELOOP]		Too many symbolic links	were encountered in translat-
			ing the	pathname.

     [EINVAL]		The requested directory	is not in the mount table.

     [EBUSY]		A process is holding a reference to a file located on
			the file system.

     [EIO]		An I/O error occurred while writing cached file	system
			information.

     [EFAULT]		Dir points outside the process's allocated address
			space.

     A ufs mount can also fail if the maximum number of	file systems are cur-
     rently mounted.

SEE ALSO
     lsvfs(1), mount(8), umount(8)

BUGS
     Some of the error codes need translation to more obvious messages.

HISTORY
     Mount() and unmount() function calls appeared in Version 6	AT&T UNIX.

FreeBSD	10.1			 May 24, 1995			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | BUGS | HISTORY

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=mount&sektion=2&manpath=FreeBSD+5.0-RELEASE>

home | help