Man Linux: Main Page and Category List


       amd - automatically mount file systems


       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 ] ] ...


       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.


       -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

       -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, 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.

       -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.


       /a   directory under which filesystems are dynamically mounted

            default configuration file


       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


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

       ‘‘am-utils’’ info(1) entry.

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

       Amd - The 4.4 BSD Automounter


       Jan-Simon  Pendry <>, Department of Computing, Imperial
       College, London, UK.

       Erez Zadok  <>,  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