RECON(1)							     LAM TOOLS								  RECON(1)

NAME

       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  config-
	      ured.   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.

   Remote shell invocation
       Note  that  the default remote shell command can be overriden at invocation time with the LAMRSH environment variable.  The LAMRSH environ-
       ment variable can be set with a new command and optional command line arguments. For example, 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 derrivates):

	      setenv LAMRSH "ssh -x"

       Normally, recon uses two remote shell invocations to each node.	The first remote shell invocation is used to determine 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  therefore  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

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), wipe(1), lam-helpfile(5)

LAM 6.5.8							  November, 2002							  RECON(1)