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NetBSD 6.1.5 - man page for amd (netbsd section 8)

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AMD(8)											   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}  selec-
	      tor.

       -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  sys-
	      log(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 retrans-
	      mit 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  docu-
	      mented  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 per-
	      formance, 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  implementa-
       tions 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 <jsp@doc.ic.ac.uk>, Department of Computing,  Imperial	College,  London,
       UK.

       Erez Zadok <ezk@cs.sunysb.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)
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