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



NAME
       amd - automatically mount file systems

SYNOPSIS
       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 interval.interval ]
       [ -w interval ] [ -x log-option ] [ -y YP-domain ] [ -A arch ] [ -C
       cluster-name ] [ -D option ] [ -F conf_file ] [ -O op_sys_name ] [ -T
       tag ] [ directory mapname [ -map-options ] ] ...

DESCRIPTION
       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 have become 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.

       In the first form depicted above, amd will print a short help string.
       In the second form, if no options are specified, or 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.

OPTIONS



       -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 then 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 messages via syslog(3) using the LOG_LOCAL7 facility (if it
              exists on the system).


       -n     Normalize hostnames.  The name refereed to by ${rhost} is
              normalized 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
              compatibility 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 filesystems 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
              standard error.


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


       -x options
              Specify run-time logging options.  The options are a comma
              separated list chosen from: fatal, error, user, warn, info, map,
              stats, defaults, and all.  Note that "fatal" and "error" are
              mandatory and cannot be turned off.


       -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.


       -A arch
              Specifies the OS architecture.  This is used solely to set the
              ${arch} selector.


       -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 strings 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.


       -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
              available via the configuration file facility.  The
              configuration file specified by this option is processed after
              all other options had 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 improves amd's
              performance, 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.


FILES
       /a   directory under which filesystems are dynamically mounted

       /etc/amd.conf
            default configuration file

CAVEATS
       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 symlink is encountered during a lookuppn
       translation it costs an RPC call to the NFS server.  It would appear
       that a large improvement in real-time performance could be gained by
       adding a cache somewhere.  Replacing symlinks 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.

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

       ``am-utils'' info(1) entry.

       Linux NFS and Automounter Administration by Erez Zadok, ISBN
       0-7821-2739-8, (Sybex, 2001).

       http://www.am-utils.org

       Amd - The 4.4 BSD Automounter

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

       Erez Zadok <ezkATcs.edu>, Computer Science Department, Stony
       Brook University, Stony Brook, New York, USA.

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



                                3 November 1989                         AMD(8)