AMD(8)AMD(8)NAMEamd - automatically mount file systems
SYNOPSISamd-H
amd [ -F conf_file ]
amd [ -nprvHS ] [ -a mount_point ] [ -c duration ] [ -d
domain ] [ -k kernel-arch ] [ -l logfile ] [ -o op_sys_ver
] [ -t interval.interval ] [ -w interval ] [ -x log-option
] [ -y YP-domain ] [ -C cluster-name ] [ -D option ] [ -F
conf_file ] [ -O op_sys_name ] [ -T tag ] [ directory map-
name [ -map-options ] ] ...
DESCRIPTION
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.
Amd operates by attaching itself as an NFS server to each
of the specified directories. Lookups within the speci-
fied 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 filesystem
information and some mount options for the given filesys-
tem.
In the first form depicted above, amd will print a short
help string. In the second form, if no options are speci-
fied, or 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 /a.
-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.
3 November 1989 1
AMD(8)AMD(8)-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 syslog facil-
ity 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 refereed to by
${rhost} is normalized 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 compatibility 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 stan-
dard output where it can be saved into a file.
-r Restart existing mounts. Amd will scan the mount
file table to determine which filesystems are cur-
rently mounted. Whenever one of these would have
been auto-mounted, amd inherits it.
-t interval.interval
Specify the 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.
-v Version. Displays version and configuration infor-
mation on standard error.
-w interval
Specify an interval, in seconds, between attempts
to dismount filesystems that have exceeded their
cached times. The default is 2 minutes.
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AMD(8)AMD(8)-x options
Specify run-time logging options. The options are
a comma separated 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.
-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 strings 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 documented here:
the current supported set of options is listed by
the -v option and a fuller description is available
in the program 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 com-
mand line. The amd.conf 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 loca-
tion 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 sys-
tem. Useful when the built in name is not desired
for backward compatibility reasons. For example,
if the build in name is ``sunos5'', you can over-
ride it to ``sos5'', and use older maps which were
written with the latter in mind.
3 November 1989 3
AMD(8)AMD(8)-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
improves amd's performance, at the cost of reserv-
ing 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
/a directory under which filesystems 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 filesystem can be incredibly
inefficient. In most implementations of NFS, their inter-
polations are not cached by the kernel and each time a
symlink 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 features.
SEE ALSOamd.conf(5), amq(8), domainname(1), hostname(1), auto-
mount(8), mount(8), umount(8), mtab(5), syslog(3).
Amd - The 4.4 BSD Automounter
AUTHORS
Jan-Simon Pendry <jsp@doc.ic.ac.uk>, Department of Comput-
ing, Imperial College, London, UK.
Erez Zadok <ezk@cs.columbia.edu>, Department of Computer
Science, Columbia University, New York, USA.
3 November 1989 4
AMD(8)AMD(8)
Other authors and contributors to am-utils are listed in
the AUTHORS file distributed with am-utils.
3 November 1989 5
