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NAME    [Toc]    [Back]

     amd - automatically mount file systems

SYNOPSIS    [Toc]    [Back]

     amd [-nprv] [-a mount_point] [-c duration] [-d  domain]  [-k
         [-l  logfile]  [-t  interval.interval] [-w interval] [-x
         [-y YP-domain] [-C cluster-name] [-D option]  [directory
         [-map-options]] ...

DESCRIPTION    [Toc]    [Back]

     amd  is a daemon that automatically mounts filesystems whenever a file or
     directory within that filesystem is  accessed.   Filesystems
are automatically
 unmounted when they appear to be quiescent.

     amd operates by attaching itself as an NFS server to each of
the specified
 directories.  Lookups within the specified  directories
are handled
     by  amd,  which uses the map defined by mapname to determine
how to resolve
     the lookup.  Generally, this  will  be  a  host  name,  some
filesystem information
 and some mount options for the given filesystem.

     The options are as follows:

     -a temporary-directory
             Specify  an  alternative location for the real mount
points.  The
             default is /a.

     -c duration
             Specify a duration, in seconds,  that  a  looked  up
name remains
             cached when not in use.  The default is 5 minutes.

     -d domain
             Specify  the  local  domain name.  If this option is
not given the
             domain name is determined from the hostname.

     -k kernel-arch
             Specifies the kernel  architecture.   This  is  used
solely to set
             the ${karch} selector.

     -l logfile
             Specify  a  logfile in which to record mount and unmount events.
             If logfile is the string syslog,  the  log  messages
will be sent to
             the system log daemon by syslog(3).

     -n       Normalize  hostnames.   The  name  referred  to  by
${rhost} is normalized
 relative to  the  host  database  before  being
used.  The effect
             is to translate aliases into ``official'' names.

     -p       Print  PID.  Outputs the process ID of amd to standard output
             where it can be saved into a file.

     -r      Restart existing mounts.  amd will  scan  the  mount
file table to
             determine  which  filesystems are currently mounted.
Whenever one
             of these would have been auto-mounted, amd  inherits

     -t interval.interval
             Specify the interval, in tenths of a second, between
             retries.  The default is 0.8  seconds.   The  second
value alters
             the  retransmit  counter.   Useful defaults are supplied if either
             or both values are missing.

     -v      Version.  Displays version and configuration  information on standard

     -w interval
             Specify an interval, in seconds, between attempts to
             filesystems that have exceeded their  cached  times.
The default
             is 2 minutes.

     -y domain
             Specify  an  alternative  NIS  domain  from which to
fetch the NIS
             maps.  The default is the system domain name.   This
option is ignored
 if NIS support is not available.

     -x options
             Specify run-time logging options.  The options are a
comma separated
 list chosen from: fatal,  error,  user,  warn,
info, map,
             stats, all.

     -D option
             Select  from  a variety of debug options.  Prefixing
an option with
             the string ``no'' reverses the effect  of  that  option.  Options
             are cumulative.  The most useful option is all.

     Since  -D  is only used for debugging, other options are not
     here: the current supported set of options is listed by  the
-v option and
     a fuller description is available in the program source.

FILES    [Toc]    [Back]

     /a     directory  under  which  filesystems  are dynamically

SEE ALSO    [Toc]    [Back]

     hostname(1), amq(8), mount(8), umount(8)

     Amd - The 4.4 BSD Automounter, available by  running  ``info

HISTORY    [Toc]    [Back]

     The amd utility first appeared in 4.4BSD.

AUTHORS    [Toc]    [Back]

     Jan-Simon  Pendry  <jsp@doc.ic.ac.uk>, Department of Computing, Imperial
     College, London, UK.

CAVEATS    [Toc]    [Back]

     Some care may be required when creating a mount map.

     Symbolic links on an NFS filesystem can be incredibly  inefficient.  In
     most  implementations  of  NFS, their interpolations are not
cached by the
     kernel and each time a symbolic link is encountered during a
     translation it costs an RPC call to the NFS server.  A large
     in real-time performance could be gained by adding  a  cache
     Replacing  symlink(2) with a suitable incarnation of the auto-mounter results
 in a large real-time speedup, but also causes a  large
number of
     process context switches.

     A weird imagination is most useful to gain full advantage of
all the features.

OpenBSD     3.6                          April      19,      1994
[ Back ]
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