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NAME

       recon - Check if LAM can be started.

SYNOPSIS

       recon [-a] [-b] [-d] [-h] [-v] [-nn] [-np] [-ssi key value] [bhost]

OPTIONS

       -a      Report all host errors.

       -b      Assume local and remote shell are the same.  This means that only one remote shell
               invocation is used to each node.  If -b is not used, two remote shell  invocations
               are used to each node.

       -d      Turn on debugging.

       -h      Print the command help menu.

       -ssi key value
               Send arguments to various SSI modules.  See the "SSI" section, below.

       -v      Be verbose.

       -nn     Don't add "-n" to the remote agent command line

       -np     Do not force the execution of $HOME/.profile on remote hosts

DESCRIPTION

       In  order  for LAM to be started on a remote UNIX machine, several requirements have to be
       fulfilled:

       1)     The machine must be reachable via the network.

       2)     The user must be able to remotely execute on the machine with  the  default  remote
              shell program that was chosen when LAM was configured.  This is usually rsh(1), but
              any remote shell program is acceptable (such as ssh(1), etc.).   Note  that  remote
              host  permission must be configured such that the remote shell program will not ask
              for a password when a command is invoked on remote host.

       3)     The remote user's shell must have a search path that will locate LAM executables.

       4)     The remote shell's startup file must not print  anything  to  standard  error  when
              invoked non-interactively.

       If any of these requirements is not met for any machine declared in bhost, LAM will not be
       able to start.  By running recon first, the user will be  able  to  quickly  identify  and
       correct problems in the setup that would inhibit LAM from starting.

       The local machine where recon is invoked must be one of the machines specified in bhost.

       The  bhost  file  is  a  LAM  boot  schema written in the host file syntax.  See bhost(5).
       Instead of the command line, a boot schema can be specified in  the  LAMBHOST  environment
       variable.   Otherwise  a default file, bhost.def, is used.  LAM seaches for bhost first in
       the local directory and then in the installation directory under etc/.

       recon tests each machine defined in bhost by attempting to  execute  on  it  the  tkill(1)
       command  using  its  "pretend"  option  (no  action  is taken).  This test, if successful,
       indicates that all the requirements listed above are met, and thus LAM can be  started  on
       the  machine.   If  the  attempt  is successful, the next machine is checked.  In case the
       attempt fails, a descriptive error message is displayed and  recon  stops  unless  the  -a
       option is used, in which case recon continues checking the remaining machines.

       If  recon  takes a long time to finish successfully, this will be a good indication to the
       user that the LAM system to be started has slow  communication  links  or  heavily  loaded
       machines,  and  it  might  be preferable to exclude or replace some of the machines in the
       system.

   SSI (System Services Interface)
       The -ssi switch allows the passing of  parameters  to  various  SSI  modules.   LAM's  SSI
       modules  are  described  in  detail  in  lamssi(7).  SSI modules have direct impact on MPI
       programs because they allow tunable parameters to be set at run time (such as  which  boot
       device driver to use, what parameters to pass to that driver, etc.).

       The  -ssi switch takes two arguments: key and value.  The key argument generally specifies
       which SSI module will receive the value.  For example, the key "boot" is  used  to  select
       which  RPI  to  be used for starting processes on remote nodes.  The value argument is the
       value that is passed.  For example:

       recon -ssi boot tm
           Tells LAM to use the "tm" boot  module  for  native  launching  in  PBSPro  /  OpenPBS
           environments (the tm boot module does not require a boot schema).

       recon -ssi boot rsh -ssi rsh_agent "ssh -x" boot_file
           Tells  LAM  to  use the "rsh" boot module, and tells the rsh module to use "ssh -x" as
           the specific agent to launch executables on remote nodes.

       And so on.  LAM's boot SSI modules are described in lamssi_boot(7).  This page  should  be
       consulted  for  specific actions that are taken by, and how to tweak the run-time behavior
       of each boot module.

       The -ssi switch can  be  used  multiple  times  to  specify  different  key  and/or  value
       arguments.   If the same key is specified more than once, the values are concatenated with
       a comma (",") separating them.

       Note that the -ssi switch is simply a shortcut for  setting  environment  variables.   The
       same  effect  may  be  accomplished  by setting corresponding environment variables before
       running  lamboot.   The  form  of  the  environment   variables   that   LAM   sets   are:
       LAM_MPI_SSI_key=value.

       Note  that  the -ssi switch overrides any previously set environment variables.  Also note
       that unknown key arguments are still set as environment variable -- they are  not  checked
       (by  lamwipe)  for  correctness.   Illegal  or incorrect value arguments may or may not be
       reported -- it depends on the specific SSI module.

   Remote Executable Invocation
       All tweakable aspects of launching executables on remote nodes during recon are  discussed
       in  lamssi(7)  and  lamssi_boot(7).  Topics include (but are not limited to): discovery of
       remote shell, run-time overrides of the agent use to launch remote executables (e.g.,  rsh
       and ssh), etc.

FILES

       laminstalldir/etc/lam-bhost.def   default  boot  schema file, where "laminstalldir" is the
                                         directory where LAM/MPI was installed.

EXAMPLES

       recon -v mynodes
           Check if LAM can be started on all the UNIX machines  described  in  the  boot  schema
           mynodes.  Report about important steps as they are done.

       recon -v -a
           Check  if  LAM  can  be started on all the UNIX machines described in the default boot
           schema.  Report about important steps as they are done.  Check all  the  machines;  do
           not stop after the first error message.

SEE ALSO

       rsh(1),   tkill(1),   bhost(5),   lamboot(1),   lamwipe(1),   lam-helpfile(5),  lamssi(7),
       lamssi_boot(7)