18.2.222. MPI_Info_env — Open MPI 5.0.2 documentation

# 18.2.222. MPI_Info_env

MPI_Info_env — Static MPI_Info object containing info about the application

## 18.2.222.1. DESCRIPTION

The MPI-3 standard established a static MPI_Info object named MPI_Info_env that can be used to access information about how the application was executed from the run-time.

## 18.2.222.2. SUPPORTED FIELDS

command

  If available, the value will be set to argv[0]. Note that the value may not always be available - e.g., it is valid for a program to call MPI_Init with NULL parameters, in which case argv[0] will not be set if run as a singleton. This value will never be set in a Fortran program as the argv are not available.

argv

  The argv given for the application. If no arguments are passed to the application, then this value will not be set. It will also not be set in the case of a singleton that calls MPI_Init with NULL parameters, or a Fortran program.

maxprocs

  The number of processes in the job.

soft

  Open MPI does not support the soft option for specifying the number of processes to be executed, so this value is set to the same as maxprocs.

host

  The name of the host this process is executing upon - the value returned from gethostname().

arch

  The architecture of the host this process is executing upon. This value indicates the underlying chip architecture (e.g., x86_64), if it can be determined.

wdir

  The working directory at the time of process launch by mpiexec. Note that this value will not be set for processes launched as singletons as there is no reliable way for the MPI library to determine the location.

file

  Although specified by the MPI-3 standard, no value is currently set for this field.

thread_level

  The requested MPI thread level - note that this may differ from the actual MPI thread level of the application.

ompi_num_apps

  The number of application contexts in an MPMD job. This is an Open MPI-specific field and value.

ompi_np

  The number of processes in each application context, provided as a space-delimited list of integers. This is an Open MPI-specific field and value.

ompi_first_rank

  The MPI rank of the first process in each application context, provided as a space-delimited list of integers This is an Open MPI-specific field and value.

ompi_positioned_file_dir

  If Open MPI was asked to pre-position files, this field provides the top-level directory where those files were place. This is an Open MPI-specific field and value.

## 18.2.222.3. ERRORS

When calling MPI_Info_get, the flag parameter will be set to zero (false) if a value for the field has not been set.

See also

- MPI_Info_get