usage:
mpiexec [-h or -help or --help]    # get this message
mpiexec -file filename             # (or -f) filename contains XML job description
mpiexec [global args] [local args] executable [args]
   where global args may be
      -l                           # line labels by MPI rank
      -bnr                         # MPICH1 compatibility mode
      -machinefile                 # file mapping procs to machines
      -s <spec>                    # direct stdin to "all" or 1,2 or 2-4,6 
      -1                           # override default of trying 1st proc locally
      -ifhn                        # network interface to use locally
      -tv                          # run procs under totalview (must be installed)
      -tvsu                        # totalview startup only
      -gdb                         # run procs under gdb
      -m                           # merge output lines (default with gdb)
      -a                           # means assign this alias to the job
      -ecfn                        # output_xml_exit_codes_filename
      -recvtimeout <integer_val>   # timeout for recvs to fail (e.g. from mpd daemon)
      -g<local arg name>           # global version of local arg (below)
    and local args may be
      -n <n> or -np <n>            # number of processes to start
      -wdir <dirname>              # working directory to start in
      -umask <umask>               # umask for remote process
      -path <dirname>              # place to look for executables
      -host <hostname>             # host to start on
      -soft <spec>                 # modifier of -n value
      -arch <arch>                 # arch type to start on (not implemented)
      -envall                      # pass all env vars in current environment
      -envnone                     # pass no env vars
      -envlist <list of env var names> # pass current values of these vars
      -env <name> <value>          # pass this value of this env var
mpiexec [global args] [local args] executable args : [local args] executable...
mpiexec -gdba jobid                # gdb-attach to existing jobid
mpiexec -configfile filename       # filename contains cmd line segs as lines
  (See User Guide for more details)

Examples:
   mpiexec -l -n 10 cpi 100
   mpiexec -genv QPL_LICENSE 4705 -n 3 a.out

   mpiexec -n 1 -host foo master : -n 4 -host mysmp slave