mount, umount - mount and unmount filesystems.


     #include <sys/mount.h>
     #include <linux/fs.h>        /* very unwise */

     int mount(const char *specialfile, const char * dir ,  const
     char  *  filesystemtype, unsigned long rwflag , const void *

     int umount(const char *specialfile));

     int umount(const char *dir));


     mount  attaches  the  filesystem  specified  by  specialfile
     (which is often a device name) to the directory specified by

     umount removes the attachment of the filesystem specified by
     specialfile or dir.

     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 rwflag argument has the magic number 0xC0ED in  the  top
     16   bits,   and   various   mount   flags  (as  defined  in
     <linux/fs.h>) 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 /* disallow access to device special files */
     #define MS_NOEXEC    8 /* disallow program execution */
     #define MS_SYNC     16 /* writes are synced at once */
     #define MS_REMOUNT  32 /* alter flags of a mounted FS */
     #define MS_MGC_VAL 0xC0ED0000
     If the magic number is absent, then the last  two  arguments
     are not used.

     The data argument is interpreted by the different file  sys-


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


     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 kernel
     source code for details.

     EPERM   The user is not the super-user.

     ENODEV  Filesystemtype not configured in the kernel.

     ENOTBLK Specialfile is not a block device (if a  device  was

     EBUSY   Specialfile is already mounted.  Or,  it  cannot  be
             remounted  read-only,  because  it still holds files
             open for writing.  Or, it cannot be mounted  on  dir
             because  dir is still busy (it is the working direc-
             tory of some task, the mount point of  another  dev-
             ice, has open files, etc.).

     EINVAL  Specialfile  had  an  invalid  superblock.   Or,   a
             remount  was  attempted,  while  specialfile was not
             already  mounted  on  dir.   Or,   an   umount   was
             attempted, while dir was not a mount point.

     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.

             A pathname was longer than MAXPATHLEN.

     ENOENT  A pathname was empty or had a nonexistent component.

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

     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 Specialfile  is  located  on  a
             filesystem mounted with the MS_NODEV option.

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

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


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


     mount(8), umount(8)