bionic (8) amd.8.gz

Provided by: am-utils_6.2+rc20110530-3.2ubuntu2_amd64 bug

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.

SEE ALSO

       amq(8), domainname(1), hostname(1), syslog(3).  amd.conf(5), mtab(5), automount(8), mount(8), umount(8),

       ``am-utils'' info(1) entry.

       Linux NFS and Automounter Administration by Erez Zadok, ISBN 0-7821-2739-8, (Sybex, 2001).

       http://www.am-utils.org

       Amd - The 4.4 BSD Automounter

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)