recon - Check if LAM can be started.


SYNTAX

       recon [-abdhv] [<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.

       -v      Be verbose.


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 usu­
              ally  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 pass­
              word 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 any­
              thing to standard error when  invoked  non-interac­
              tively.

       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

       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.

   Remote shell invocation
       Note that the default remote shell command can be  overri­
       den  at  invocation time with the LAMRSH environment vari­
       able.  The LAMRSH environment variable can be set  with  a
       new command and optional command line arguments. For exam­
       ple, the 1.x series of ssh clients require the -x flag  to
       be  specified  to  suppress  standard ssh information from
       being sent to the standard error (which would cause  recon
       to  fail).   For  example  (for  the  C shell and its der­
       rivates):

              setenv LAMRSH "ssh -x"

       Normally, recon uses two remote shell invocations to  each
       node.  The first remote shell invocation is used to deter­
       mine the user's shell on  the  remote  node.   The  second
       remote  shell invocation is used to launch the desired LAM
       binary on the remote node.  If  the  -b  switch  is  used,
       recon  will  assume  that  the  user's shell on all remote
       nodes is the same as it is on the local node,  and  there­
       fore  only  one  remote shell invocation is used, which is
       noticably faster.

       In either case, on remote nodes, if the  user's  shell  is
       not  csh, tcsh, or bash, .profile is invoked by LAM before
       invoking any LAM binary.  This allows the  user  to  setup
       paths  and  any  necessary environment before LAM binaries
       are invoked (csh and tcsh users  can  put  such  setup  in
       their  $HOME/.cshrc or $HOME/.tcshrc files; bash users can
       put this setup in their $HOME/.bashrc file).


FILES

       $LAMHOME/etc/lam-bhost.def        default boot schema file

       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), wipe(1), lam-help­
       file(5)


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