MOUNT(ADM)                           UNIX System V



     Name
          mount - mounts and unmounts a file structure


     Syntax
          /etc/mount [-v] [-r] [-f fstyp] special directory

          /etc/umount special-device


     Description
          mount  announces  to  the  system  that  a  removable   file
          structure  is  present on special-device. The file structure
          is mounted on directory. The directory must  already  exist;
          it  becomes  the  name of the root of the newly mounted file
          structure.   directory  should  be  empty.    If   directory
          contains  files, they will appear to have been removed while
          the  special-device  is  mounted  and  reappear   when   the
          special-device is unmounted.

          The mount and umount commands maintain a  table  of  mounted
          devices.   If  mount  is  invoked  without any arguments, it
          displays the name of each mounted device, and the  directory
          on  which it is mounted, whether the file structure is read-
          only, and the date it was mounted.

          The -f fstyp option indicates that fstyp is the file  system
          type  to  be  mounted.   If  this  argument  is  omitted, it
          defaults to the root fstyp.

          The optional -r argument indicates that the file  is  to  be
          mounted    read-only.    Physically   write-protected   file
          structures, such as floppy disks  with  write-protect  tabs,
          must  be  mounted  in  this  way or errors occur when access
          times are updated, whether or  not  any  explicit  write  is
          attempted.

          The  optional  -v  argument   displays   mount   information
          verbosely.

          umount  removes  the  removable  file  structure  on  device
          special-device.  Any  pending  I/O  for  the  file system is
          completed and the file structure is marked as clean.


     Files
          /etc/mnttab         Mount table

          /etc/default/filesys
                              Filesystem data


     See Also
          umount(ADM),  mnt(C),   mount(S),   mnttab(F),   default(F),
          setmnt(ADM)

     Diagnostics
          mount issues a warning  if  directory  does  not  match  the
          s_fname  field  in  the  superblock  of the filesystem to be
          mounted.  The first six characters in the last component  of
          directory  are  compared  with  the  name  in s_fname (i.e.,
          mounting a filesystem named spool on /usr/spool won't  cause
          a  warning message, but mounting the same filesystem on /mnt
          will.).

          Busy file structures cannot be  dismounted  with  umount.  A
          file  structure  is busy if it contains an open file or some
          user's working directory.


     Notes
          Only the super-user can use the mount command.

          Some degree of validation is done  on  the  file  structure,
          however  it  is  generally  unwise  to  mount  corrupt  file
          structures.

          Be warned that when in single-user mode, the  commands  that
          look  in  /etc/mnttab for default arguments (for example df,
          ncheck, quot,  mount,  and  umount)  give  either  incorrect
          results  (due  to  a corrupt /etc/mnttab from a non-shutdown
          stoppage) or no results (due  to  an  empty  mnttab  from  a
          shutdown stoppage).

          When multi-user, this is not a problem; the /etc/rc2 scripts
          initialize   /etc/mnttab   to  contain  only  /dev/root  and
          subsequent mounts update it appropriately.

          The mount(ADM) and umount(ADM) commands use a lock  file  to
          guarantee  exclusive  access  to  /etc/mnttab.  The commands
          which just read it (those mentioned above) do not, so it  is
          possible  that they may hit a window, which is corrupt. This
          is not a problem in practice since mount and umount are  not
          frequent operations.

          When mounting a file system on a floppy disk  you  need  not
          use  the  same  directory each time. However, if you do, the
          full pathnames for the files are consistent with each use.

          Always unmount filesystems on floppy disks  before  removing
          them  from  the  floppy  drive.   Failure  to do so requires
          running fsck the next time the disk is mounted .

          The directory /etc/fscmd.d/TYPE contains programs  for  each
          file  system  type;  mount/umount  invokes  the  appropriate
          binary.


     Standards Conformance
          mount is conformant with:
          AT&T SVID Issue 2, Select Code 307-127;
          and The X/Open Portability Guide II of January 1987.


     (printed 2/15/90)                                 MOUNT(ADM)