mount(ADM)                    06 January 1993                     mount(ADM)


 Name

    mount - mount and unmount a file structure

 Syntax

    /etc/mount [ -v ] [ -r ] [ -f fstyp ] special-device 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 optional -r argument indicates that the file is to be mounted read-
    only.  Physically write-protected filesystems, 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.

    The -f fstyp option indicates that fstyp is the type of filesystem to be
    mounted.  If this argument is omitted, it defaults to the same filesystem
    type as the root directory. Use the fstyp(ADM) command to find the file-
    system type for your system:

       /etc/fstyp /dev/root

    The filesystem types which may be mounted are:

    AFS       Acer Fast Filesystems.

    DOS       DOS filesystems.

    EAFS      Extended Acer Fast Filesystems.

    HS        High Sierra CD-ROM filesystems. The following option modifiers
              may be attached to this type:

              lower          Convert case of filenames to lower. The default
                             is to use upper case.

              showhidden     Show hidden files. The default is not to show
                             hidden files.

              version        Display version numbers. The default is not to
                             display version numbers.

              The options must be separated from each other and from the
              filesystem type using commas (,) and not including spaces. For
              example:

              /etc/mount  -r  -f  HS,lower,version  /dev/cd0  /cdrom


    S51K      AT&T UNIX System V 1 Kbyte filesystems.

    XENIX     XENIX 286/386 filesystems.

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

 Files

    /etc/mnttab     mount table
    /etc/default/filesys
                    filesystem data

 See also

    default(F), fstyp(ADM), mnt(C), mount(S), mnttab(F), setmnt(ADM) and
    umount(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 charac-
    ters in the last component of directory are compared with the name in
    ``s_fname''. (For example, mounting a filesystem named spool on
    /usr/spool won't cause a warning message, but mounting the same file-
    system on /mnt will.)

    Busy filesystems cannot be dismounted with umount.  A filesystem 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 filesystem, however it is gen-
    erally unwise to mount corrupt filesystems.

    If the mount command is invoked without a target directory, but with a
    valid filesystem as an argument, mount attempts to mount the system on
    the directory named in its entry in /etc/default/filesys. For further in-
    formation, refer to filesys(F).

    Note that when the system is in single-user mode, the commands that look
    in /etc/mnttab for default arguments (for example df(C), ncheck(ADM),
    quot(C), mount, and umount) give either incorrect results (due to a cor-
    rupt mnttab(F) left over from a non-shutdown stoppage) or no results (due
    to an empty /etc/mnttab from a shutdown stoppage).

    When in multi-user mode, this is not a problem; the /etc/bcheckrc script
    initializes /etc/mnttab to contain only /dev/root, and subsequent mounts
    update it appropriately.

    The mount and umount commands use a lock file to guarantee exclusive
    access to /etc/mnttab.  The other commands which read it (those mentioned
    above) do not, so it is possible that if they are invoked while a file
    system is being mounted or unmounted they will return incorrect values.
    This is not a problem in practice since mount and umount are not frequent
    operations.

    When mounting a filesystem 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(ADM) the next time
    the disk is mounted.

    The directories /etc/fscmd.d/fstyp contain programs that are dependent on
    the filesystem type; mount or umount invokes the appropriate binary.

 Standards conformance

    mount is conformant with:

    AT&T SVID Issue 2;
    and X/Open Portability Guide, Issue 3, 1989.