Unix/Linux Go Back    


NetBSD 6.1.5 - man page for mount (netbsd section 2)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


MOUNT(2)			     BSD 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, size_t data_len);

     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, and is data_len bytes
     long.  The argument type tells the kernel how to interpret data (See type below).	The con-
     tents 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 unavail-
     able 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.

     MNT_UNION	      Union with underlying filesystem instead of obscuring it.

     MNT_HIDDEN       Cause the df(1) program, and perhaps others, to, by default, exclude this
		      filesystem from its output.

     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 executing them.

     MNT_NODEV	      Do not interpret special files on the file system.

     MNT_NOCOREDUMP   Do not allow programs to dump core files on the file system.

     MNT_NOATIME      Never update access time in the file system.

     MNT_RELATIME     Update access time on write and change.  This helps programs that verify
		      that the file has been read after written to work.

     MNT_NODEVMTIME   Never update modification time of device files.

     MNT_SYMPERM      Recognize the permission of symbolic link when reading or traversing.

     MNT_SYNCHRONOUS  All I/O to the file system should be done synchronously.	This will slow
		      I/O performance considerably, but enhances overall filesystem reliability.

     MNT_ASYNC	      All I/O to the file system should be done asynchronously.  This vastly
		      improves I/O throughput, but at a cost of making the filesystem likely to
		      be completely unrecoverable should the system crash while unwritten data is
		      pending in kernel buffers.

     MNT_LOG	      Use a filesystem journal.  MNT_LOG causes a journal (or log) to be created
		      in the filesystem, creating a record of meta-data writes to be performed,
		      allowing the actual writes to be deferred.  This improves performance in
		      most cases.

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

     The MNT_UPDATE, MNT_RELOAD, and MNT_GETARGS flags indicate that the mount command is being
     applied to an already mounted file system.  The MNT_UPDATE flag allows the mount flags to be
     changed without requiring that the file system be unmounted and remounted.  A conversion
     from read-write to read-only will fail if any files are currently open for writing on the
     filesystem, unless the MNT_FORCE flag is also applied.  Some file systems may not allow all
     flags to be changed.  For example, some file systems will not allow a change from read-write
     to read-only.  The MNT_RELOAD flag causes kernel filesystem data to be reloaded from the
     filesystem device.  It is only permitted on filesystems mounted read-only.  Its purpose is
     to notify the system that the filesystem data has been modified by some external process.
     The MNT_GETARGS flag does not alter any of the mounted filesystem's properties, but returns
     the filesystem-specific arguments for the currently mounted filesystem.

     The type argument defines the type of the file system.  The types of file systems known to
     the system are defined in <sys/mount.h>, and those supported by the current running kernel
     obtained using sysctl(8) to obtain the node vfs.generic.fstypes.  data is a pointer to a
     structure that contains the type specific arguments to mount.  Some of the currently sup-
     ported types of file systems and their type specific data are:

     MOUNT_FFS
	   struct ufs_args {
		 char	   *fspec;	       /* block special file to mount */
	   };

     MOUNT_NFS
	   struct nfs_args {
		 int		 version;      /* args structure version */
		 struct sockaddr *addr;        /* file server address */
		 int		 addrlen;      /* length of address */
		 int		 sotype;       /* Socket type */
		 int		 proto;        /* and Protocol */
		 u_char 	 *fh;	       /* File handle to be mounted */
		 int		 fhsize;       /* Size, in bytes, of fh */
		 int		 flags;        /* flags */
		 int		 wsize;        /* write size in bytes */
		 int		 rsize;        /* read size in bytes */
		 int		 readdirsize;  /* readdir size in bytes */
		 int		 timeo;        /* initial timeout in .1 secs */
		 int		 retrans;      /* times to retry send */
		 int		 maxgrouplist; /* Max. size of group list */
		 int		 readahead;    /* # of blocks to readahead */
		 int		 leaseterm;    /* Term (sec) of lease */
		 int		 deadthresh;   /* Retrans threshold */
		 char		 *hostname;    /* server's name */
	   };

     MOUNT_MFS
	   struct mfs_args {
		 char	   *fspec;	       /* name to export for statfs */
		 struct    export_args30 pad;  /* unused */
		 caddr_t   base;	       /* base of file system in mem */
		 u_long    size;	       /* size of file system */
	   };

     The unmount() function call disassociates the file system from the specified mount point
     dir.

     The flags argument may specify MNT_FORCE to specify that the file system should be forcibly
     unmounted 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.

RETURN VALUES
     mount() returns the value 0 if the mount was successful, the number of bytes written to data
     for MNT_GETARGS, otherwise -1 is returned and the variable errno is set to indicate the
     error.

     unmount() returns the value 0 if the unmount succeeded; otherwise -1 is returned and the
     variable errno is set to indicate the error.

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

     [EBUSY]		Another process currently holds a reference to dir, or for an update from
			read-write to read-only there are files on the filesystem open for
			writes.

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

     [ELOOP]		Too many symbolic links were encountered in translating a pathname.

     [ENAMETOOLONG]	A component of a pathname exceeded {NAME_MAX} characters, or an entire
			path name exceeded {PATH_MAX} characters.

     [ENOENT]		A component of dir does not exist.

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

     [EPERM]		The caller is not the super-user, and ordinary user mounts are not per-
			mitted or this particular request violates the rules.

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

     [EBUSY]		Fspec is already mounted.

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

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

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

     [EMFILE]		No space remains in the mount table.

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

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

     [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).

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

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

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

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

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

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

     [EIO]		A paging error occurred while reading the super block or cylinder group
			information.

     [EMFILE]		No space remains in the mount table.

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

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

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

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

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

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

     [ELOOP]		Too many symbolic links were encountered in translating the pathname.

     [ENAMETOOLONG]	A component of a pathname exceeded {NAME_MAX} characters, or an entire
			path name exceeded {PATH_MAX} characters.

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

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

     A ufs or mfs mount can also fail if the maximum number of file systems are currently
     mounted.

SEE ALSO
     df(1), getvfsstat(2), nfssvc(2), getmntinfo(3), symlink(7), mount(8), sysctl(8), umount(8)

HISTORY
     The mount() and umount() (now unmount()) function calls were all present in Version 6 AT&T
     UNIX.

     Prior to NetBSD 4.0 the mount call was used to export NFS filesystems.  This is now done
     through nfssvc().

     The data_len argument was added for NetBSD 5.0.

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

     Far more filesystems are supported than those those listed.

BSD					November 18, 2011				      BSD
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 01:53 AM.