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AMD(8)			FreeBSD	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 timeout.retransmit] [-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
     The amd utility is	a daemon that automatically mounts file	systems	when-
     ever a file or directory within that file system is accessed.  File sys-
     tems are automatically unmounted when they	appear to be quiescent.

     The amd utility 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 file sys-
     tem information 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.

OPTIONS
     -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'', then the log messages	will
	     be	sent to	the system log daemon by syslog(3).  The default sys-
	     log 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 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.  The amd utility 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.

	     The amd(8)	utility	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.

     -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 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(5) 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 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 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.

FILES
     /.amd_mnt	    directory under which file systems 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 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.  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 fea-
     tures.

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

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

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

     http://www.am-utils.org/

     Amd - The 4.4 BSD Automounter.

HISTORY
     The amd utility first appeared in 4.4BSD.

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.

FreeBSD	10.1			January	2, 2006			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FILES | CAVEATS | SEE ALSO | HISTORY | AUTHORS

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