/*D

    mpiexec - Run an MPI program

   Synopsis:

.vb

    mpiexec args executable pgmargs [ : args executable pgmargs ... ]

.ve

   where 'args' are command line arguments for 'mpiexec' (see below), 

   'executable' is the name of an executable MPI program, and 'pgmargs'

   are command line arguments for the executable.  Multiple executables 

   can be specified by using the colon notation (for MPMD - Multiple Program

   Multiple Data applications).

   Standard Parameters:

.N mpiexecstdargs

   Environment Variables:

   The following environment variables affect the behavior of 'mpiexec'\:

+  MPIEXEC_UNIVERSE_SIZE - Sets the maximum number of processes to allow.

.  MPIEXEC_TIMEOUT - Maximum running time in seconds.  'mpiexec' will

   terminate MPI programs that take longer than the value specified by

   'MPIEXEC_TIMEOUT'.  This version of 'mpiexec' (forker process manager)

   sets a default timelimit of 3 minutes (180 seconds) since the forker

   process manager is intended for debugging applications.

.  MPIEXEC_PREFIX_DEFAULT - If this environment variable is set, output

   to standard output is prefixed by the rank in 'MPI_COMM_WORLD' of the 

   process and output to standard error is prefixed by the rank and the 

   text '(err)'; both are followed by an angle bracket ('>').  If

   this variable is not set, there is no prefix.

.  MPIEXEC_PREFIX_STDOUT - Set the prefix for output from standard output.

   This is a string containing text and (optionally) the expression '%d';

   if '%d' is seen, it is replaced by the rank in 'MPI_COMM_WORLD' of the 

   process.  If there is more than one 'MPI_COMM_WORLD'; for example, 

   if 'MPI_Comm_spawn' is used, the expression '%w' is replaced with a

   numeric `world number`, assigned by 'mpiexec'.  The expression '%%' 

   produces a single percent character.

.  MPIEXEC_PREFIX_STDERR - Like 'MPIEXEC_PREFIX_STDOUT', but for output from

   standard error.

.  MPIEXEC_STDIN_DEST - Sets the destination process for input from standard in,

   by rank in the corresponding 'MPI_COMM_WORLD'.

.  MPIEXEC_STDOUTBUF - Sets the buffering mode for standard output.  Valid

   values are 'NONE' (no buffering), 'LINE' (buffering by lines), and

   'BLOCK' (buffering by blocks of characters; the size of the block is

   implementation defined).  The default is 'NONE'.

-  MPIEXEC_STDERRBUF - Like 'MPIEXEC_STDOUTBUF', but for standard error.

   Note that the 'MPIEXEC_PREFIX_xxx' and 'MPIEXEC_STDIN_DEST' variables

   are not fully implemented.

   Startup Environment:

   All of the users environment variables are provided to each of the 

   created processes.  This is not required by the MPI standard, but 

   is often very convenient.  

   Return Status:

   'mpiexec' returns the maximum of the exit status values of all of the

   processes created by 'mpiexec'.  

   Notes:

   A few additional enviroment variables are defined for the use of

   developers and in debugging.  These are

.  MPIEXEC_DEBUG - If set, 'mpiexec' will write additional information

   about the steps that it is taking.

D*/