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1 .\" $NetBSD: amd.8,v 1.1.1.2 2009/03/20 20:26:48 christos Exp $
2 .\"
3 .\"
4 .\" Copyright (c) 1997-2009 Erez Zadok
5 .\" Copyright (c) 1989 Jan-Simon Pendry
6 .\" Copyright (c) 1989 Imperial College of Science, Technology & Medicine
7 .\" Copyright (c) 1989 The Regents of the University of California.
8 .\" All rights reserved.
9 .\"
10 .\" This code is derived from software contributed to Berkeley by
11 .\" Jan-Simon Pendry at Imperial College, London.
12 .\"
13 .\" Redistribution and use in source and binary forms, with or without
14 .\" modification, are permitted provided that the following conditions
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16 .\" 1. Redistributions of source code must retain the above copyright
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18 .\" 2. Redistributions in binary form must reproduce the above copyright
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20 .\" documentation and/or other materials provided with the distribution.
21 .\" 3. All advertising materials mentioning features or use of this software
22 .\" must display the following acknowledgment:
23 .\" This product includes software developed by the University of
24 .\" California, Berkeley and its contributors.
25 .\" 4. Neither the name of the University nor the names of its contributors
26 .\" may be used to endorse or promote products derived from this software
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28 .\"
29 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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31 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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40 .\"
41 .\"
42 .\" File: am-utils/amd/amd.8
43 .\"
44 .TH AMD 8 "3 November 1989"
45 .SH NAME
46 amd \- automatically mount file systems
47 .SH SYNOPSIS
48 .B amd
49 .B \-H
50 .br
51 .B amd
52 [
53 .BI \-F " conf_file"
54 ]
55 .br
56 .B amd
57 [
58 .B \-nprvHS
59 ] [
60 .BI \-a " mount_point"
61 ] [
62 .BI \-c " duration"
63 ] [
64 .BI \-d " domain"
65 ] [
66 .BI \-k " kernel-arch"
67 ] [
68 .BI \-l " logfile"
69 ] [
70 .BI \-o " op_sys_ver"
71 ] [
72 .BI \-t " interval.interval"
73 ] [
74 .BI \-w " interval"
75 ] [
76 .BI \-x " log-option"
77 ] [
78 .BI \-y " YP-domain"
79 ] [
80 .BI \-A " arch"
81 ] [
82 .BI \-C " cluster-name"
83 ] [
84 .BI \-D " option"
85 ] [
86 .BI \-F " conf_file"
87 ] [
88 .BI \-O " op_sys_name"
89 ] [
90 .BI \-T " tag"
91 ]
92 [
93 .I directory
94 .I mapname
95 .RI [ " \-map-options " ]
96 ] .\|.\|.
97 .SH DESCRIPTION
98 .B Amd
99 is a daemon that automatically mounts filesystems
100 whenever a file or directory
101 within that filesystem is accessed.
102 Filesystems are automatically unmounted when they
103 appear to have become quiescent.
104 .LP
105 .B Amd
106 operates by attaching itself as an
107 .SM NFS
108 server to each of the specified
109 .IB directories .
110 Lookups within the specified directories
111 are handled by
112 .BR amd ,
113 which uses the map defined by
114 .I mapname
115 to determine how to resolve the lookup.
116 Generally, this will be a host name, some filesystem information
117 and some mount options for the given filesystem.
118 .LP
119 In the first form depicted above,
120 .B amd
121 will print a short help string. In the second form, if no options are
122 specified, or the
123 .B -F
124 is used,
125 .B amd
126 will read configuration parameters from the file
127 .I conf_file
128 which defaults to
129 .BR /etc/amd.conf .
130 The last form is described below.
131 .SH OPTIONS
133 .\"*******************************************************"
135 .TP
136 .BI \-a " temporary-directory"
137 Specify an alternative location for the real mount points.
138 The default is
139 .BR /a .
141 .TP
142 .BI \-c " duration"
143 Specify a
144 .IR duration ,
145 in seconds, that a looked up name remains
146 cached when not in use. The default is 5 minutes.
148 .TP
149 .BI \-d " domain"
150 Specify the local domain name. If this option is not
151 given the domain name is determined from the hostname.
153 .TP
154 .BI \-k " kernel-arch"
155 Specifies the kernel architecture. This is used solely
156 to set the ${karch} selector.
158 .TP
159 .BI \-l " logfile"
160 Specify a logfile in which to record mount and unmount events.
161 If
162 .I logfile
163 is the string
164 .B syslog
165 then the log messages will be sent to the system log daemon by
166 .IR syslog (3).
167 The default syslog facility used is LOG_DAEMON. If you
168 wish to change it, append its name to the log file name, delimited by a
169 single colon. For example, if
170 .I logfile
171 is the string
172 .B syslog:local7
173 then
174 .B Amd
175 will log messages via
176 .IR syslog (3)
177 using the LOG_LOCAL7 facility (if it exists on the system).
179 .TP
180 .B \-n
181 Normalize hostnames.
182 The name refereed to by ${rhost} is normalized relative to the
183 host database before being used. The effect is to translate
184 aliases into ``official'' names.
186 .TP
187 .BI \-o " op_sys_ver"
188 Override the compiled-in version number of the operating system. Useful
189 when the built in version is not desired for backward compatibility reasons.
190 For example, if the build in version is ``2.5.1'', you can override it to
191 ``5.5.1'', and use older maps that were written with the latter in mind.
193 .TP
194 .B \-p
195 Print PID.
196 Outputs the process-id of
197 .B amd
198 to standard output where it can be saved into a file.
200 .TP
201 .B \-r
202 Restart existing mounts.
203 .B Amd
204 will scan the mount file table to determine which filesystems
205 are currently mounted. Whenever one of these would have
206 been auto-mounted,
207 .B amd
208 .I inherits
209 it.
211 .TP
212 .BI \-t " timeout.retransmit"
213 Specify the NFS timeout
214 .IR interval ,
215 in tenths of a second, between NFS/RPC retries (for UDP only). The default
216 is 0.8 seconds. The second value alters the retransmit counter, which
217 defaults to 11 retransmissions. Both of these values are used by the kernel
218 to communicate with amd. Useful defaults are supplied if either or both
219 values are missing.
221 Amd relies on the kernel RPC retransmit mechanism to trigger mount retries.
222 The values of these parameters change the overall retry interval. Too long
223 an interval gives poor interactive response; too short an interval causes
224 excessive retries.
226 .TP
227 .B \-v
228 Version. Displays version and configuration information on standard error.
230 .TP
231 .BI \-w " interval"
232 Specify an
233 .IR interval ,
234 in seconds, between attempts to dismount
235 filesystems that have exceeded their cached times.
236 The default is 2 minutes.
238 .TP
239 .BI \-x " options"
240 Specify run-time logging options. The options are a comma separated
241 list chosen from: fatal, error, user, warn, info, map, stats, defaults, and
242 all. Note that "fatal" and "error" are mandatory and cannot be turned off.
244 .TP
245 .BI \-y " domain"
246 Specify an alternative NIS domain from which to fetch the NIS maps.
247 The default is the system domain name. This option is ignored if NIS
248 support is not available.
250 .TP
251 .BI \-A " arch"
252 Specifies the OS architecture. This is used solely to set the ${arch}
253 selector.
255 .TP
256 .BI \-C " cluster-name"
257 Specify an alternative HP-UX cluster name to use.
259 .TP
260 .BI \-D " option"
261 Select from a variety of debug options. Prefixing an
262 option with the strings
263 .B no
264 reverses the effect of that option. Options are cumulative.
265 The most useful option is
266 .BR all .
267 Since
268 .I \-D
269 is only used for debugging other options are not documented here:
270 the current supported set of options is listed by the \-v option
271 and a fuller description is available in the program source.
273 .TP
274 .BI \-F " conf_file"
275 Specify an amd configuration file to use. See
276 .BR amd.conf (5)
277 for description of this file's format. This configuration file is used to
278 specify any options in lieu of typing many of them on the command line. The
279 .I amd.conf
280 file includes directives for every command line option amd has, and many
281 more that are only available via the configuration file facility. The
282 configuration file specified by this option is processed after all other
283 options had been processed, regardless of the actual location of this option
284 on the command line.
286 .TP
287 .B \-H
288 Print help and usage string.
290 .TP
291 .BI \-O " op_sys_name"
292 Override the compiled-in name of the operating system. Useful when the
293 built in name is not desired for backward compatibility reasons. For
294 example, if the build in name is ``sunos5'', you can override it to
295 ``sos5'', and use older maps which were written with the latter in mind.
297 .TP
298 .B \-S
299 Do not lock the running executable pages of amd into memory. To improve
300 amd's performance, systems that support the
301 .BR plock (3)
302 call, could lock the amd process into memory. This way there is less chance
303 the operating system will schedule, page out, and swap the amd process as
304 needed. This tends improves amd's performance, at the cost of reserving the
305 memory used by the amd process (making it unavailable for other processes).
306 If this behavior is not desired, use the
307 .B \-S
308 option.
310 .TP
311 .BI \-T " tag"
312 Specify a tag to use with
313 .BR amd.conf (5).
314 All map entries tagged with
315 .I tag
316 will be processed. Map entries that are not tagged are always processed.
317 Map entries that are tagged with a tag other than
318 .I tag
319 will not be processed.
321 .SH FILES
322 .TP 5
323 .B /a
324 directory under which filesystems are dynamically mounted
325 .TP 5
326 .B /etc/amd.conf
327 default configuration file
328 .SH CAVEATS
329 Some care may be required when creating a mount map.
330 .LP
331 Symbolic links on an NFS filesystem can be incredibly inefficient.
332 In most implementations of NFS, their interpolations are not cached
333 by the kernel and each time a symlink is encountered during a
334 .I lookuppn
335 translation it costs an RPC call to the NFS server.
336 It would appear that a large improvement in real-time
337 performance could be gained by adding a cache somewhere.
338 Replacing symlinks with a suitable incarnation of the auto-mounter
339 results in a large real-time speedup, but also causes a large
340 number of process context switches.
341 .LP
342 A weird imagination is most useful to gain full advantage of all
343 the features.
344 .SH "SEE ALSO"
345 .BR domainname (1),
346 .BR hostname (1),
347 .BR syslog (3).
348 .BR amd.conf (5),
349 .BR mtab (5),
350 .BR amq (8),
351 .\" .BR automount (8),
352 .BR mount (8),
353 .BR umount (8),
354 .LP
355 ``am-utils''
356 .BR info (1)
357 entry.
358 .LP
359 .I "Linux NFS and Automounter Administration"
360 by Erez Zadok, ISBN 0-7821-2739-8, (Sybex, 2001).
361 .LP
362 .I http://www.am-utils.org
363 .LP
364 .I "Amd \- The 4.4 BSD Automounter"
365 .SH AUTHORS
366 Jan-Simon Pendry <jsp@doc.ic.ac.uk>, Department of Computing, Imperial College, London, UK.
367 .P
368 Erez Zadok <ezk@cs.sunysb.edu>, Computer Science Department, Stony Brook
369 University, Stony Brook, New York, USA.
370 .P
371 Other authors and contributors to am-utils are listed in the
372 .B AUTHORS
373 file distributed with am-utils.