Ubuntu Manpage: amd - automatically mount file systems

Provided by: am-utils_6.2+rc20110530-3.2ubuntu1_amd64

NAME

       amd - automatically mount file systems

SYNOPSIS

       amd -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  ]  [  -A  arch  ]  [  -C cluster-name ] [ -D option ] [ -F conf_file ] [ -O
       op_sys_name ] [ -T tag ] [ directory mapname [ -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 specified 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 filesystem.

       In the first form depicted above, amd will print a short help string.  In the second form,
       if no options are specified, 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.

-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 facility 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 standard 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 currently mounted. Whenever one of these would have been auto-
mounted, amd inherits it.

-t timeout.retransmit
Specify the NFS timeout interval, in tenths of a second, between 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.

Amd 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.

-v Version. Displays version and configuration information 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.

-x options
Specify run-time logging options. The options are a comma separated list chosen
from: fatal, error, user, warn, info, map, stats, defaults, and all. Note that
"fatal" and "error" are mandatory and cannot be turned off.

-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.

-A arch
Specifies the OS architecture. This is used solely to set the ${arch} selector.

-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 command 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
location 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 system. Useful when the built in
name is not desired for backward compatibility reasons. For example, if the build
in name is ``sunos5'', you can override it to ``sos5'', and use older maps which
were written with the latter in mind.

-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 reserving 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 interpolations 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.

AUTHORS

       Jan-Simon Pendry <jsp@doc.ic.ac.uk>, Department of Computing,  Imperial  College,  London,
       UK.

       Erez Zadok <ezk@cs.sunysb.edu>, Computer Science Department, Stony Brook University, Stony
       Brook, New York, USA.

       Other authors and contributors to am-utils are listed in the AUTHORS file distributed with
       am-utils.

                                         3 November 1989                                   AMD(8)