MOUNT(T)            Linux Programmer's Manual            MOUNT(T)



NAME
       mount, umount - mount and unmount filesystems.

SYNOPSIS
       #include <sys/mount.h>

       int  mount(const  char *source, const char *target , const
       char *filesystemtype, unsigned  long  mountflags  ,  const
       void *data);

       int umount(const char *target);

DESCRIPTION
       mount  attaches  the filesystem specified by source (which
       is often a device name, but can also be a  directory  name
       or a dummy) to the directory specified by target.

       umount  removes the attachment of the (topmost) filesystem
       mounted on target.

       Only the super-user may mount and unmount filesystems.

       The filesystemtype argument may take  one  of  the  values
       listed   in   /proc/filesystems   (like  "minix",  "ext2",
       "msdos", "proc", "nfs", "iso9660" etc.).

       The mountflags argument may have the magic  number  0xC0ED
       in the top 16 bits, and various mount flags (as defined in
       <linux/fs.h> for libc4 and libc5 and in <sys/mount.h>  for
       glibc2) in the low order 16 bits:

       #define MS_RDONLY        1 /* mount read-only */
       #define MS_NOSUID        2 /* ignore suid and sgid bits */
       #define MS_NODEV         4 /* no access to device special files */
       #define MS_NOEXEC        8 /* no program execution */
       #define MS_SYNCHRONOUS  16 /* writes are synced at once */
       #define MS_REMOUNT      32 /* alter flags of a mounted fs */
       #define MS_MANDLOCK     64 /* allow mandatory locks */
       #define MS_NOATIME    1024 /* do not update access times */
       #define MS_NODIRATIME 2048 /* do not update dir access times */
       #define MS_BIND       4096 /* bind subtree elsewhere */
       #define MS_MOVE       8192 /* atomically move subtree */

       The  data  argument  is  interpreted by the different file
       systems.


RETURN VALUE
       On success, zero is returned.  On error, -1  is  returned,
       and errno is set appropriately.

ERRORS
       The  error  values given below result from filesystem type
       independent errors. Each filesystem type may have its  own
       special errors and its own special behavior.  See the ker-
       nel source code for details.


       EPERM  The user is not the super-user.

       ENODEV Filesystemtype not configured in the kernel.

       ENOTBLK
              Source is not a block  device  (and  a  device  was
              required).

       EBUSY  Source   is  already  mounted.  Or,  it  cannot  be
              remounted read-only, because it still  holds  files
              open for writing.  Or, it cannot be mounted on tar-
              get because target is still busy (it is the working
              directory  of some task, the mount point of another
              device, has open files, etc.).

       EINVAL Source had an invalid superblock.   Or,  a  remount
              was attempted, while source was not already mounted
              on target.  Or, a move was attempted, while  source
              was  not  a mount point, or was '/'.  Or, an umount
              was attempted, while target was not a mount  point.

       ENOTDIR
              The second argument, or a prefix of the first argu-
              ment, is not a directory.

       EFAULT One of the pointer  arguments  points  outside  the
              user address space.

       ENOMEM The  kernel  could not allocate a free page to copy
              filenames or data into.

       ENAMETOOLONG
              A pathname was longer than MAXPATHLEN.

       ENOENT A pathname was empty or had  a  nonexistent  compo-
              nent.

       ELOOP  Too  many  link encountered during pathname resolu-
              tion.  Or, a move was attempted, while target is  a
              descendant of source.

       EACCES A component of a path was not searchable.
              Or,  mounting  a read-only filesystem was attempted
              without giving the MS_RDONLY flag.
              Or,  the  block  device  Source  is  located  on  a
              filesystem mounted with the MS_NODEV option.

       ENXIO  The  major number of the block device source is out
              of range.

       EMFILE (In case no block device  is  required:)  Table  of
              dummy devices is full.

CONFORMING TO
       These  functions are Linux-specific and should not be used
       in programs intended to be portable.

HISTORY
       The original umount function was called as  umount(t)
       and  would return ENOTBLK when called with something other
       than a block device.  In Linux 0.98p4 a  call  umount(t)
       was  added,  in  order  to  support anonymous devices.  In
       Linux 2.3.99-pre7 the  call  umount(t)  was  removed,
       leaving only umount(t) (since now devices can be mounted
       in more than one place, so specifying the device does  not
       suffice).

       The  original  MS_SYNC  flag was renamed MS_SYNCHRONOUS in
       1.1.69 when a different MS_SYNC was added to <mman.h>.

       Before Linux 2.4 an attempt to execute a set-UID  or  set-
       GID  program  on a filesystem mounted with MS_NOSUID would
       fail with EPERM.  Since Linux 2.4 the set-UID and  set-GID
       bits are just silently ignored in this case.

SEE ALSO
       mount(t), umount(t)



Linux 2.5                   2001-12-20                   MOUNT(T)