1AMD(8) System Manager's Manual AMD(8)
2
6 amd - automatically mount file systems
7
9 amd -H
10 amd [ -F conf_file ]
11 amd [ -nprvHS ] [ -a mount_point ] [ -c duration ] [ -d domain ] [ -k
12 kernel-arch ] [ -l logfile ] [ -o op_sys_ver ] [ -t interval.interval ]
13 [ -w interval ] [ -x log-option ] [ -y YP-domain ] [ -A arch ] [ -C
14 cluster-name ] [ -D option ] [ -F conf_file ] [ -O op_sys_name ] [ -T
15 tag ] [ directory mapname [ -map-options ] ] ...
16
18 Amd is a daemon that automatically mounts filesystems whenever a file
19 or directory within that filesystem is accessed. Filesystems are auto‐
20 matically unmounted when they appear to have become quiescent.
21 Amd operates by attaching itself as an NFS server to each of the speci‐
23 fied directories. Lookups within the specified directories are handled
24 by amd, which uses the map defined by mapname to determine how to
25 resolve the lookup. Generally, this will be a host name, some filesys‐
26 tem information and some mount options for the given filesystem.
27 In the first form depicted above, amd will print a short help string.
29 In the second form, if no options are specified, or the -F is used, amd
30 will read configuration parameters from the file conf_file which
31 defaults to /etc/amd.conf. The last form is described below.
32
34 -a temporary-directory
35 Specify an alternative location for the real mount points. The
36 default is /a.
37 -c duration
40 Specify a duration, in seconds, that a looked up name remains
41 cached when not in use. The default is 5 minutes.
42 -d domain
45 Specify the local domain name. If this option is not given the
46 domain name is determined from the hostname.
47 -k kernel-arch
50 Specifies the kernel architecture. This is used solely to set
51 the ${karch} selector.
52 -l logfile
55 Specify a logfile in which to record mount and unmount events.
56 If logfile is the string syslog then the log messages will be
57 sent to the system log daemon by syslog(3). The default syslog
58 facility used is LOG_DAEMON. If you wish to change it, append
59 its name to the log file name, delimited by a single colon. For
60 example, if logfile is the string syslog:local7 then Amd will
61 log messages via syslog(3) using the LOG_LOCAL7 facility (if it
62 exists on the system).
63 -n Normalize hostnames. The name refereed to by ${rhost} is nor‐
66 malized relative to the host database before being used. The
67 effect is to translate aliases into ``official'' names.
68 -o op_sys_ver
71 Override the compiled-in version number of the operating system.
72 Useful when the built in version is not desired for backward
73 compatibility reasons. For example, if the build in version is
74 ``2.5.1'', you can override it to ``5.5.1'', and use older maps
75 that were written with the latter in mind.
76 -p Print PID. Outputs the process-id of amd to standard output
79 where it can be saved into a file.
80 -r Restart existing mounts. Amd will scan the mount file table to
83 determine which filesystems are currently mounted. Whenever one
84 of these would have been auto-mounted, amd inherits it.
85 -t timeout.retransmit
88 Specify the NFS timeout interval, in tenths of a second, between
89 NFS/RPC retries (for UDP only). The default is 0.8 seconds.
90 The second value alters the retransmit counter, which defaults
91 to 11 retransmissions. Both of these values are used by the
92 kernel to communicate with amd. Useful defaults are supplied if
93 either or both values are missing.
94 Amd relies on the kernel RPC retransmit mechanism to trigger
96 mount retries. The values of these parameters change the over‐
97 all retry interval. Too long an interval gives poor interactive
98 response; too short an interval causes excessive retries.
99 -v Version. Displays version and configuration information on
102 standard error.
103 -w interval
106 Specify an interval, in seconds, between attempts to dismount
107 filesystems that have exceeded their cached times. The default
108 is 2 minutes.
109 -x options
112 Specify run-time logging options. The options are a comma sepa‐
113 rated list chosen from: fatal, error, user, warn, info, map,
114 stats, all.
115 -y domain
118 Specify an alternative NIS domain from which to fetch the NIS
119 maps. The default is the system domain name. This option is
120 ignored if NIS support is not available.
121 -A arch
124 Specifies the OS architecture. This is used solely to set the
125 ${arch} selector.
126 -C cluster-name
129 Specify an alternative HP-UX cluster name to use.
130 -D option
133 Select from a variety of debug options. Prefixing an option
134 with the strings no reverses the effect of that option. Options
135 are cumulative. The most useful option is all. Since -D is
136 only used for debugging other options are not documented here:
137 the current supported set of options is listed by the -v option
138 and a fuller description is available in the program source.
139 -F conf_file
142 Specify an amd configuration file to use. See amd.conf(5) for
143 description of this file's format. This configuration file is
144 used to specify any options in lieu of typing many of them on
145 the command line. The amd.conf file includes directives for
146 every command line option amd has, and many more that are only
147 available via the configuration file facility. The configura‐
148 tion file specified by this option is processed after all other
149 options had been processed, regardless of the actual location of
150 this option on the command line.
151 -H Print help and usage string.
154 -O op_sys_name
157 Override the compiled-in name of the operating system. Useful
158 when the built in name is not desired for backward compatibility
159 reasons. For example, if the build in name is ``sunos5'', you
160 can override it to ``sos5'', and use older maps which were writ‐
161 ten with the latter in mind.
162 -S Do not lock the running executable pages of amd into memory. To
165 improve amd's performance, systems that support the plock(3)
166 call, could lock the amd process into memory. This way there is
167 less chance the operating system will schedule, page out, and
168 swap the amd process as needed. This tends improves amd's per‐
169 formance, at the cost of reserving the memory used by the amd
170 process (making it unavailable for other processes). If this
171 behavior is not desired, use the -S option.
172 -T tag Specify a tag to use with amd.conf(5). All map entries tagged
175 with tag will be processed. Map entries that are not tagged are
176 always processed. Map entries that are tagged with a tag other
177 than tag will not be processed.
178
181 /a directory under which filesystems are dynamically mounted
182 /etc/amd.conf
184 default configuration file
185
187 Some care may be required when creating a mount map.
188 Symbolic links on an NFS filesystem can be incredibly inefficient. In
190 most implementations of NFS, their interpolations are not cached by the
191 kernel and each time a symlink is encountered during a lookuppn trans‐
192 lation it costs an RPC call to the NFS server. It would appear that a
193 large improvement in real-time performance could be gained by adding a
194 cache somewhere. Replacing symlinks with a suitable incarnation of the
195 auto-mounter results in a large real-time speedup, but also causes a
196 large number of process context switches.
197 A weird imagination is most useful to gain full advantage of all the
199 features.
200
202 amd.conf(5), amq(8), domainname(1), hostname(1), automount(8),
203 mount(8), umount(8), mtab(5), syslog(3).
204 ``am-utils'' info(1) entry.
206 Linux NFS and Automounter Administration by Erez Zadok, ISBN
208 0-7821-2739-8, (Sybex, 2001).
209 http://www.am-utils.org
211 Amd - The 4.4 BSD Automounter
213
215 Jan-Simon Pendry <jsp@doc.ic.ac.uk>, Department of Computing, Imperial
216 College, London, UK.
217 Erez Zadok <ezk@cs.sunysb.edu>, Computer Science Department, Stony
219 Brook University, Stony Brook, New York, USA.
220 Other authors and contributors to am-utils are listed in the AUTHORS
222 file distributed with am-utils.
223 3 November 1989 AMD(8)