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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 auto-
       matically unmounted when they appear to have become 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 filesys-
       tem 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 nor-
	      malized 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 restransmit 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	 over-
	      all 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 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.


       -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  configura-
	      tion  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 writ-
	      ten 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 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.



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 trans-
       lation 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

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

       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.columbia.edu>,  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.



				3 November 1989				amd(8)

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