.\" $Id: amd.8,v 5.2 90/06/23 22:21:12 jsp Rel $
.\" 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 are permitted provided
.\" that: (1) source distributions retain this entire copyright notice and
.\" comment, and (2) distributions including binaries display the following
.\" acknowledgement:  ``This product includes software developed by the
.\" University of California, Berkeley and its contributors'' in the
.\" documentation or other materials provided with the distribution and in
.\" all advertising materials mentioning features or use of this software.
.\" 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.\"	@(#)amd.8	5.1 (Berkeley) 6/29/90
.\"
.TH AMD 8 "June 29, 1990"
.SH NAME
amd \- automatically mount file systems
.SH SYNOPSIS
.B amd
[
.B \-nprv
] [
.BI \-a " mount_point"
] [
.BI \-c " duration"
] [
.BI \-d " domain"
] [
.BI \-k " kernel-arch"
] [
.BI \-l " logfile"
] [
.BI \-t " interval.interval"
] [
.BI \-w " interval"
] [
.BI \-x " log-option"
] [
.BI \-y " YP-domain"
] [
.BI \-C " cluster-name"
] [
.BI \-D " option"
]
[
.I directory
.I mapname
.RI [ " \-map-options " ]
] .\|.\|.
.SH DESCRIPTION
.B 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.
.LP
.B Amd
has been designed as a value-added replacement
for the SunOS 4
.IR automount (8)
program.
Considerable design effort has been expended in making
.B amd
robust in the face of
.SM NFS
servers going down.
.B Amd
operates by attaching itself as an
.SM NFS
server to each of the specified
.IB directories .
Lookups within the specified directories
are handled by
.BR amd ,
which uses the map contained in
.I 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.
.SH OPTIONS
.TP
.B \-n
Normalize hostnames.
The name refered to by ${rhost} are normalized relative to the
host database before being used.  The effect is to translate
aliases into ``official'' names.
.TP
.B \-p
Print PID.
Outputs the process-id of
.B amd
to standard output where it can be saved into a file.
.TP
.B \-r
Restart existing mounts.
.B Amd
will scan the mount file table to determine which filesystems
are currently mounted.  Whenever one of these would have
been auto-mounted,
.B amd
.I inherits
it.
.TP
.B \-v
Version.  Displays version and configuration information on standard error.
If you send a bug report, this should be used to determine
which version of
.B amd
you are using.
.TP
.BI \-a " temporary-directory"
Specify an alternative location for the real mount points.
The default is
.BR /a .
.TP
.BI \-c " duration"
Specify a
.IR duration ,
in seconds, that a looked up name remains
cached when not in use.  The default is 5 minutes.
.TP
.BI \-d " domain"
Specify the local domain name.  If this option is not
given the domain name is determined from the hostname.
.TP
.BI \-k " kernel-arch"
Specifies the kernel architecture.  This is used solely
to set the ${karch} selector.
.TP
.BI \-l " logfile"
Specify a logfile in which to record mount and unmount events.
If
.I logfile
is the string
.B syslog
then the log messages will be sent to the system log daemon by
.IR syslog (3).
This is only available on certain systems (e.g.
.I not
.SM HP-UX
and early versions of Ultrix).
.TP
.BI \-t " interval.interval"
Specify the
.IR interval ,
in tenths of a second, between NFS/RPC/UDP retries.
The default is 0.8 seconds.
The second values alters the restransmit counter.
Useful defaults are supplied if either or both
values are missing.
.TP
.BI \-w " interval"
Specify an
.IR interval ,
in seconds, between attempts to dismount
filesystems that have exceeded their cached times.
The default is 2 minutes.
.TP
.BI \-y " domain"
Specify an alternative YP domain from which to fetch the YP maps.
The default is the system domain name.
.TP
.BI \-x " options"
Specify run-time logging options.  The options are a comma separated
list chosen from: fatal, error, user, warn, info, all.
.TP
.BI \-D " option"
Select from a variety of debug options.  Prefixing an
option with the strings
.B no
reverses the effect of that option.  Options are cumulative.
The most useful option is
.BR all .
Since
.I \-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.
.SH FILES
.PD 0
.TP 5
.B /a
directory under which filesystems are dynamically mounted
.PD
.SH CAVEATS
Some care may be required when creating a mount map.
.LP
Symbolic links on an NFS filesystem are incredibly inefficient.
Their interpolations are not cached by the kernel and each time a symlink is
encountered during a
.I 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.
.LP
A weird imagination is most useful to gain full advantage of all
the features.
.SH "SEE ALSO"
.BR amq (8),
.BR domainname (1),
.BR hostname (1),
.BR automount (8),
.BR mount (8),
.BR umount (8),
.BR mtab (5),
.LP
.I "Amd \- An Automounter"
.SH AUTHOR
Jan-Simon Pendry <jsp@doc.ic.ac.uk>, Department of Computing, Imperial College, London, UK.