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RocketLink!--> Man page versions: OpenBSD FreeBSD NetBSD Others

AMD(8)                  OpenBSD System Manager's Manual                 AMD(8)

     amd - automatically mount file systems

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

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

     Amd operates by attaching itself as an NFS server to each of the speci-
     fied 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 infor-
     mation and some mount options for the given filesystem.

     -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 normal-
             ized 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 it.

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

     -v      Version.  Displays version and configuration information on stan-
             dard error.

     -w interval
             Specify an interval, in seconds, between attempts to dismount
             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 ig-
             nored if NIS support is not available.

     -x options
             Specify run-time logging options.  The options are a comma sepa-
             rated 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 documented
     here: the current supported set of options is listed by the -v option and
     a fuller description is available in the program source.

     /a    directory under which filesystems are dynamically mounted

     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 lookuppn
     translation it costs an RPC call to the NFS server.  A large improvement
     in real-time performance could be gained by adding a cache somewhere.
     Replacing symlinks(2) with a suitable incarnation of the auto-mounter re-
     sults 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 fea-

     amq(8),  fsinfo(8),  hostname(1),  mk-amd-map(8),  mount(8),  umount(8).

     Amd - The 4.4 BSD Automounter.

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

     The amd utility first appeared in 4.4BSD.

OpenBSD 2.3                     April, 19, 1994                              2

Source: OpenBSD 2.6 man pages. Copyright: Portions are copyrighted by BERKELEY
SOFTWARE DESIGN, INC., The Regents of the University of California, Massachusetts
Institute of Technology, Free Software Foundation, FreeBSD Inc., and others.

(Corrections, notes, and links courtesy of RocketAware.com)

[Detailed Topics]
FreeBSD Sources for amd(8)
OpenBSD sources for amd(8)

[Overview Topics]

Up to: Specific Types of File Systems - Specific forms of file systems. DFS, NFS, MS-DOS, etc.
Up to: File System Operations - Operations for entire file-systems (quotas, configuration, consistency, mount, unmount, et al)

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