Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
AMD(8)                  FreeBSD System Manager's Manual                 AMD(8)

     amd -- automatically mount file systems

     amd -H
     amd [-F conf_file]
     amd [-nprvHS] [-a mount_point] [-c duration] [-d domain] [-k kernel-arch]
         [-l logfile] [-o op_sys_ver] [-t timeout.retransmit] [-w interval]
         [-x log-option] [-y YP-domain] [-C cluster-name] [-D option]
         [-F conf_file] [-O op_sys_name] [-T tag] [directory mapname
         [-map-options]] ...

     Amd is a daemon that automatically mounts file systems whenever a file or
     directory within that file system is accessed.  File systems are automat-
     ically 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 file system infor-
     mation and some mount options for the given file system.

     In the first form depicted above, amd will print a short help string.  In
     the second form, if no options are specified, or if the -F is used, amd
     will read configuration parameters from the file conf_file which defaults
     to /etc/amd.conf.  The last form is described below.

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

     -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).  The default syslog facility
             used is LOG_DAEMON.  If you wish to change it, append its name to
             the log file name, delimited by a single colon.  For example, if
             logfile is the string ``syslog:local7'' then amd will log mes-
             sages via syslog(3) using the LOG_LOCAL7 facility (if it exists
             on the system).

     -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.

     -o op_sys_ver
             Override the compiled-in version number of the operating system.
             Useful when the built in version is not desired for backward com-
             patibility reasons.  For example, if the build in version is
             ``2.5.1'', you can override it to ``5.5.1'', and use older maps
             that were written with the latter in mind.

     -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 file systems are currently mounted.  Whenever one
             of these would have been auto-mounted, amd inherits it.

     -t timeout.retransmit
             Specify the NFS timeout interval, in tenths of a second, between
             NFS/RPC retries (for UDP only).  The default is 0.8 seconds.  The
             second value alters the retransmit counter, which defaults to 11
             retransmissions.  Both of these values are used by the kernel to
             communicate with amd.  Useful defaults are supplied if either or
             both values are missing.

             Amd relies on the kernel RPC retransmit mechanism to trigger
             mount retries.  The values of these parameters change the overall
             retry interval.  Too long an interval gives poor interactive
             response; too short an interval causes excessive retries.

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

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

     -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.

     -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.

     -C cluster-name
             Specify an alternative HP-UX cluster name to use.

     -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 docu-
             mented here: the current supported set of options is listed by
             the -v option and a fuller description is available in the pro-
             gram source.

     -F conf_file
             Specify an amd configuration file to use.  See amd.conf(5) for
             description of this file's format.  This configuration file is
             used to specify any options in lieu of typing many of them on the
             command line.  The amd.conf file includes directives for every
             command line option amd has, and many more that are only avail-
             able via the configuration file facility.  The configuration file
             specified by this option is processed after all other options
             have been processed, regardless of the actual location of this
             option on the command line.

     -H      Print help and usage string.

     -O op_sys_name
             Override the compiled-in name of the operating system.  Useful
             when the built in name is not desired for backward compatibility
             reasons.  For example, if the build in name is ``sunos5'', you
             can override it to ``sos5'' and use older maps which were written
             with the latter in mind.

     -S      Do not lock the running executable pages of amd into memory.  To
             improve amd's performance, systems that support the plock(3)
             call, could lock the amd process into memory.  This way there is
             less chance the operating system will schedule, page out, and
             swap the amd process as needed.  This tends to improve amd's per-
             formance, at the cost of reserving the memory used by the amd
             process (making it unavailable for other processes).  If this
             behavior is not desired, use the -S option.

     -T tag  Specify a tag to use with amd.conf(5).  All Map entries tagged
             with tag will be processed.  Map entries that are not tagged are
             always processed.  Map entries that are tagged with a tag other
             than tag will not be processed.

           directory under which file systems are dynamically mounted

           default configuration file

     Some care may be required when creating a mount map.

     Symbolic links on an NFS file system 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 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 fea-

     domainname(1), hostname(1), syslog(3), amd.conf(5), mtab(5), amq(8),
     mount(8), umount(8)

     Amd - The 4.4 BSD Automounter.

     The amd utility first appeared in 4.4BSD.

     Jan-Simon Pendry <>, Department of Computing, Imperial
     College, London, UK.

     Erez Zadok <>, Department of Computer Science, Columbia
     University, New York, USA.

     Other authors and contributors to am-utils are listed in the AUTHORS file
     distributed with am-utils.

FreeBSD 6.2                     April 19, 1994                     FreeBSD 6.2


Want to link to this manual page? Use this URL:

home | help