.\"
.\" Copyright (c) 1997-2006 Erez Zadok
.\" Copyright (c) 1989 Jan-Simon Pendry
.\" Copyright (c) 1989 Imperial College of Science, Technology & Medicine
.\" Copyright (c) 1989 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Jan-Simon Pendry at Imperial College, London.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgment:
.\"      This product includes software developed by the University of
.\"      California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	%W% (Berkeley) %G%
.\"
.\" $Id: amd.8,v 1.14.2.1 2006/01/02 18:48:23 ezk Exp $
.\" $FreeBSD: release/10.0.0/contrib/amd/amd/amd.8 174415 2007-12-07 20:16:21Z ru $
.\"
.Dd January 2, 2006
.Dt AMD 8
.Os
.Sh NAME
.Nm amd
.Nd automatically mount file systems
.Sh SYNOPSIS
.Nm
.Fl H
.Nm
.Op Fl F Ar conf_file
.Nm
.Op Fl nprvHS
.Op Fl a Ar mount_point
.Op Fl c Ar duration
.Op Fl d Ar domain
.Op Fl k Ar kernel-arch
.Op Fl l Ar logfile
.Op Fl o Ar op_sys_ver
.Op Fl t Ar timeout.retransmit
.Op Fl w Ar interval
.Op Fl x Ar log-option
.Op Fl y Ar YP-domain
.Op Fl A Ar arch
.Op Fl C Ar cluster-name
.Op Fl D Ar option
.Op Fl F Ar conf_file
.Op Fl O Ar op_sys_name
.Op Fl T Ar tag
.Oo
.Ar directory mapname
.Op Fl map-options
.Oc
.Ar ...
.Sh DESCRIPTION
The
.Nm
utility
is a daemon that automatically mounts file systems
whenever a file or directory
within that file system is accessed.
File systems are automatically unmounted when they
appear to be quiescent.
.Pp
The
.Nm
utility
operates by attaching itself as an
.Tn NFS
server to each of the specified
.Ar directories .
Lookups within the specified directories
are handled by
.Nm ,
which uses the map defined by
.Ar mapname
to determine how to resolve the lookup.
Generally, this will be a host name, some file system information
and some mount options for the given file system.
.Pp
In the first form depicted above,
.Nm
will print a short help string.
In the second form, if no options are
specified, or if the
.Fl F
is used,
.Nm
will read configuration parameters from the file
.Ar conf_file
which defaults to
.Pa /etc/amd.conf .
The last form is described below.
.Sh OPTIONS
.Bl -tag -width indent
.It Fl a Ar temporary-directory
Specify an alternative location for the real mount points.
The default is
.Pa /.amd_mnt .
.It Fl c Ar duration
Specify a
.Ar duration ,
in seconds, that a looked up name remains
cached when not in use.
The default is 5 minutes.
.It Fl d Ar domain
Specify the local domain name.
If this option is not
given the domain name is determined from the hostname.
.It Fl k Ar kernel-arch
Specifies the kernel architecture.
This is used solely
to set the ${karch} selector.
.It Fl l Ar logfile
Specify a logfile in which to record mount and unmount events.
If
.Ar logfile
is the string
.Dq Li syslog ,
then the log messages will be sent to the system log daemon by
.Xr syslog 3 .
The default syslog facility used is
.Dv LOG_DAEMON .
If you
wish to change it, append its name to the log file name, delimited by a
single colon.
For example, if
.Ar logfile
is the string
.Dq Li syslog:local7
then
.Nm
will log messages via
.Xr syslog 3
using the
.Dv LOG_LOCAL7
facility (if it exists on the system).
.It Fl n
Normalize hostnames.
The name referred to by ${rhost} is normalized relative to the
host database before being used.
The effect is to translate
aliases into
.Dq official
names.
.It Fl o Ar 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
.Dq Li 2.5.1 ,
you can override it to
.Dq Li 5.5.1 ,
and use older maps that were written with the latter in mind.
.It Fl p
Print PID.
Outputs the process ID of
.Nm
to standard output where it can be saved into a file.
.It Fl r
Restart existing mounts.
The
.Nm
utility
will scan the mount file table to determine which file systems
are currently mounted.
Whenever one of these would have
been auto-mounted,
.Nm
.Em inherits
it.
.It Fl t Ar timeout.retransmit
Specify the NFS
.Ar timeout
interval,
in tenths of a second, between
.Tn 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.
.Pp
The
.Xr 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.
.It Fl v
Version.
Displays version and configuration information on standard error.
.It Fl w Ar interval
Specify an
.Ar interval ,
in seconds, between attempts to dismount
file systems that have exceeded their cached times.
The default is 2 minutes.
.It Fl x Ar options
Specify run-time logging options.
The options are a comma separated
list chosen from:
.Li fatal , error , user , warn , info , map , stats , all .
.It Fl y Ar domain
Specify an alternative
.Tn NIS
domain from which to fetch the
.Tn NIS
maps.
The default is the system domain name.
This option is ignored if
.Tn NIS
support is not available.
.It Fl A Ar arch
Specifies the OS architecture.
This is used solely to set the ${arch}
selector.
.It Fl C Ar cluster-name
Specify an alternative HP-UX cluster name to use.
.It Fl D Ar option
Select from a variety of debug options.
Prefixing an
option with the string
.Dq Li no
reverses the effect of that option.
Options are cumulative.
The most useful option is
.Dq Li all .
.Pp
Since
.Fl D
is only used for debugging other options are not documented here:
the current supported set of options is listed by the
.Fl v
option
and a fuller description is available in the program source.
.It Fl F Ar conf_file
Specify an
.Nm
configuration file to use.
See
.Xr 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
.Xr amd.conf 5
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.
.It Fl H
Print help and usage string.
.It Fl O Ar 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
.Dq Li sunos5 ,
you can override it to
.Dq Li sos5
and use older maps which were written with the latter in mind.
.It Fl S
Do not lock the running executable pages of
.Nm
into memory.
To improve
.Nm Ns 's
performance, systems that support the
.Xr plock 3
call, could lock the
.Nm
process into memory.
This way there is less chance
the operating system will schedule, page out, and swap the
.Nm
process as
needed.
This tends to improve
.Nm Ns 's
performance, at the cost of reserving the
memory used by the
.Nm
process (making it unavailable for other processes).
If this behavior is not desired, use the
.Fl S
option.
.It Fl T Ar tag
Specify a tag to use with
.Xr amd.conf 5 .
All map entries tagged with
.Ar tag
will be processed.
Map entries that are not tagged are always processed.
Map entries that are tagged with a tag other than
.Ar tag
will not be processed.
.El
.Sh FILES
.Bl -tag -width ".Pa /etc/amd.conf"
.It Pa /.amd_mnt
directory under which file systems are dynamically mounted
.It Pa /etc/amd.conf
default configuration file
.El
.Sh CAVEATS
Some care may be required when creating a mount map.
.Pp
Symbolic links on an
.Tn NFS
file system can be incredibly inefficient.
In most implementations of
.Tn NFS ,
their interpolations are not cached
by the kernel and each time a symbolic link is encountered during a
.Em lookuppn
translation it costs an
.Tn RPC
call to the
.Tn 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.
.Pp
A weird imagination is most useful to gain full advantage of all
the features.
.Sh SEE ALSO
.Xr domainname 1 ,
.Xr hostname 1 ,
.Xr syslog 3 ,
.Xr amd.conf 5 ,
.Xr mtab 5 ,
.Xr amq 8 ,
.Xr mount 8 ,
.Xr umount 8
.Pp
.Dq am-utils
.Xr info 1
entry.
.Rs
.%A Erez Zadok
.%B "Linux NFS and Automounter Administration"
.%O ISBN 0-7821-2739-8
.%I Sybex
.%D 2001
.Re
.Pp
.Pa http://www.am-utils.org/
.Rs
.%T Amd \- The 4.4 BSD Automounter
.Re
.Sh HISTORY
The
.Nm
utility first appeared in
.Bx 4.4 .
.Sh AUTHORS
.An Jan-Simon Pendry Aq jsp@doc.ic.ac.uk ,
Department of Computing, Imperial College, London, UK.
.Pp
.An Erez Zadok Aq ezk@cs.sunysb.edu ,
Computer Science Department, Stony Brook
University, Stony Brook, New York, USA.
.Pp
Other authors and contributors to am-utils are listed in the
.Pa AUTHORS
file distributed with am-utils.
