NAME
     sge_commd - Grid Engine communication agent

SYNOPSIS
     sge_commd [ -S ] [ -a aliasfile ] [ -dhr ] [ -help ]  [  -ll
     loglevel ] [ -ml fname ] [ -nd ] [ -p port ] [ -s service ]

DESCRIPTION
     All network communication in a Grid Engine cluster  is  per-
     formed  via the communication daemons sge_commd. Client pro-
     grams like qsub(1) or qstat(1) as well as Grid  Engine  dae-
     mons  such as sge_qmaster(8) or sge_execd(8) use the service
     provided by sge_commd  in  order  to  send/receive  messages
     to/from other Grid Engine components.

     sge_commd handles an arbitrary number of concurrent synchro-
     nous  or  asynchronous communications. Usually one sge_commd
     is  started  up  automatically  on  each   host   on   which
     sge_qmaster(8),   sge_execd(8)   or/and   sge_schedd(8)  are
     invoked. It is however possible to  connect  multiple  hosts
     via  one  sge_commd  or  to  use  a sge_commd on a submit or
     administrative Grid Engine host (without running one of  the
     other  Grid  Engine  daemons) as communication agent for the
     Grid Engine client programs invoked from that host.

OPTIONS
     -S   Forces  secure  ports  to  be  used  for  communication
          between  sge_commds  and between other Grid Engine com-
          ponents and the  sge_commds.  This  requires  all  Grid
          Engine  daemons  to be started with root permission and
          the client programs to be configured set-uid  root.  In
          turn,  it  ensures  that  unauthorized communication is
          prohibited for non-root accounts.

     -a aliasfile
          A file containing Grid Engine host aliases used by  the
          sge_commd  to  resolve Grid Engine unique hostnames for
          all hosts in the cluster. The hostname  resolving  ser-
          vice of sge_commd is also used by all other Grid Engine
          components.  The file format and the implication of its
          usage are described in sge_h_aliases(5).

     -dhr The hostname resolving  C-library  functions  (such  as
          gethostent(3),  gethostbyname(3)  and gethostbyaddr(3))
          perform some kind of caching on some OS  architectures.
          Network wide hostname databases distributed by services
          such as DNS (Domain  Name  Service)  and  NIS  (Network
          Information  Service)  are  updated  with  a  delay  of
          several minutes. This only affects  applications  which
          repeatedly  resolve  hostnames  (such as sge_commd). At
          start-up of a program the most  recent  information  is
          accessed,  thus  commands like telnet(1) or nslookup(1)
          are not affected.
          However, for sge_commd it makes  no  sense  to  resolve
          hostnames  anytime (the returned information may be out
          of date anyway)  and  resolving  can  be  an  expensive
          operation  if  the  network is overloaded and/or NIS or
          DNS  servers  are  very  busy.   Therefore,   sge_commd
          resolves hostname information from time to time only.
          Yet, if hostname resolving still causes problems due to
          network  load,  for  example, it can be turned off with
          the -dhr switch.  The administrator has  to  be  aware,
          that if the hostname resolving is turned off, sge_commd
          has to be restarted as soon as the  hostname  databases
          change significantly.

     -help
          Prints  a listing of all options.

     -ll loglevel
          Sets a logging level for error tracing. The error trace
          information      is     written     to     the     file
          /tmp/commd/err.<pid>. However, the directory /tmp/commd
          must  be  present, otherwise the tracing output is dis-
          carded. At present,  255  is  the  only  valid  logging
          level.

     -nd  Do not daemonize. If started with -nd, sge_commd  main-
          tains  its  connection  to the controlling terminal and
          thus outputs trace information directly to the terminal
          from which sge_commd was invoked. The trace information
          is the same as being accessible via the -ll option (see
          above).

     -p port_number
          Use this TCP port for communication with other commds.

     -s service_name
          Use this service name and thus the associated TCP  port
          for communication with other commds.

ENVIRONMENTAL VARIABLES
     SGE_ROOT       Specifies the location  of  the  Grid  Engine
                    standard configuration files.

     COMMD_PORT     If set,  specifies  the  tcp  port  on  which
                    sge_commd  is expected to listen for communi-
                    cation requests.  Most installations will use
                    a  services  map entry instead to define that
                    port.

     COMMD_HOST     (Does not affect the  behavior  of  sge_commd
                    but  of the other Grid Engine components con-
                    tacting sge_commd.)  If  set,  specifies  the
                    host  on which the particular sge_commd to be
                    used for Grid Engine communication  of  arbi-
                    trary  Grid Engine client programs or daemons
                    resides. Per default the local host is used.

RESTRICTIONS
     sge_commd usually is invoked by  a  starting  sge_qmaster(8)
     and  sge_execd(8) and thus is running under root permission.
     If started by a normal user the -S switch may not be used as
     the secure mode requires root permission (see above).

SEE ALSO
     sge_intro(1),        sge_h_aliases(5),         sge_execd(8),
     sge_qmaster(8), commdcntl(8).

COPYRIGHT
     See sge_intro(1) for a full statement of rights and  permis-
     sions.



































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