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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