MPI_INFO_GET_STRING(3)				     Open MPI				    MPI_INFO_GET_STRING(3)

MPI_Info_get_string — Retrieves the value associated with a key in an info object.

SYNTAX
   C Syntax
	  #include <mpi.h>

	  int MPI_Info_get_string(MPI_Info info, const char *key, int *buflen, char *value, int *flag)

   Fortran Syntax
	  USE MPI
	  ! or the older form: INCLUDE 'mpif.h'
	  MPI_INFO_GET_STRING(INFO, KEY, BUFLEN, VALUE, FLAG, IERROR)
	       INTEGER INFO, BUFLEN, IERROR
	       CHARACTER*(*) KEY, VALUE
	       LOGICAL FLAG

   Fortran 2008 Syntax
	  USE mpi_f08
	  MPI_Info_get_string(info, key, buflen, value, flag, ierror)
	       TYPE(MPI_Info), INTENT(IN) :: info
	       CHARACTER(LEN=*), INTENT(IN) :: key
	       INTEGER, INTENT(INOUT) :: buflen
	       CHARACTER(LEN=valuelen), INTENT(OUT) :: value
	       LOGICAL, INTENT(OUT) :: flag
	       INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS
       • info: Info object (handle).

       • key: Key (string).

OUTPUT PARAMETER
       • buflen On entry, length of value arg. On return, set to required size to: hold value string (integer).

       • value: Value (string).

       • flag: Returns true if key defined, false if not (boolean).

       • ierror: Fortran only: Error status (integer).

DESCRIPTION
       MPI_Info_get_string  retrieves  the  value  associated  with key from info, if any. If such a key exists in
       info, it sets flag to true and returns the value in value, otherwise it sets flag to false and leaves value
       unchanged. buflen on input is the size of the provided buffer, for the output of buflen it is the  size	of
       the buffer needed to store the value string. If the buflen passed into the function is less than the actual
       size  needed to store the value string (including null terminator in C), the value is truncated. On return,
       the value of buflen will be set to the required buffer size to hold the value string. If buflen is  set	to
       0,  value  is  not  changed.  In	 C, buflen includes the required space for the null terminator. In C, this
       function returns a null terminated string in all cases where the buflen input value is greater than 0.

       If key is larger than MPI_MAX_INFO_KEY, the call is erroneous.

ERRORS
       Almost all MPI routines return an error value; C routines as the return result of the function and  Fortran
       routines in the last argument.

       Before  the error value is returned, the current MPI error handler associated with the communication object
       (e.g., communicator, window, file) is called.  If no communication object is associated with the MPI  call,
       then  the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When
       MPI_COMM_SELF is not initialized (i.e.,	before	MPI_Init  <#mpi-init>/MPI_Init_thread  <#mpi-init-thread>,
       after  MPI_Finalize  <#mpi-finalize>,  or  when	using the Sessions Model exclusively) the error raises the
       initial error handler. The initial error handler can  be	 changed  by  calling  MPI_Comm_set_errhandler	<#
       mpi-comm-set-errhandler>	 on  MPI_COMM_SELF  when  using the World model, or the mpi_initial_errhandler CLI
       argument	 to  mpiexec  or  info	key   to   MPI_Comm_spawn   <#mpi-comm-spawn>/MPI_Comm_spawn_multiple	<#
       mpi-comm-spawn-multiple>.   If  no other appropriate error handler has been set, then the MPI_ERRORS_RETURN
       error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error  handler  is  called  for  all
       other MPI functions.

       Open MPI includes three predefined error handlers that can be used:

       • MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.

       • MPI_ERRORS_ABORT  An  error handler that can be invoked on a communicator, window, file, or session. When
	 called on a communicator, it acts as if MPI_Abort <#mpi-abort> was called on that communicator. If called
	 on a window or file, acts as if MPI_Abort <#mpi-abort> was called on a communicator containing the  group
	 of processes in the corresponding window or file. If called on a session, aborts only the local process.

       • MPI_ERRORS_RETURN Returns an error code to the application.

       MPI applications can also implement their own error handlers by calling:

       • MPI_Comm_create_errhandler	 <#mpi-comm-create-errhandler>	   then	    MPI_Comm_set_errhandler	<#
	 mpi-comm-set-errhandler>

       • MPI_File_create_errhandler	<#mpi-file-create-errhandler>	  then	   MPI_File_set_errhandler	<#
	 mpi-file-set-errhandler>

       • MPI_Session_create_errhandler	 <#mpi-session-create-errhandler>   then   MPI_Session_set_errhandler	<#
	 mpi-session-set-errhandler> or at MPI_Session_init <#mpi-session-init>

       • MPI_Win_create_errhandler	<#mpi-win-create-errhandler>	  then	    MPI_Win_set_errhandler	<#
	 mpi-win-set-errhandler>

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page <#open-mpi> for a full list of MPI error codes <#open-mpi-errors>.

       See the Error Handling section of the MPI-3.1 standard for more information.

       See also:

	  • MPI_Info_create <#mpi-info-create>

	  • MPI_Info_delete <#mpi-info-delete>

	  • MPI_Info_dup <#mpi-info-dup>

	  • MPI_Info_free <#mpi-info-free>

	  • MPI_Info_get_nkeys <#mpi-info-get-nkeys>

	  • MPI_Info_get_nthkey <#mpi-info-get-nthkey>

	  • MPI_Info_set <#mpi-info-set>

Copyright
       2003-2026, The Open MPI Community

						   Mar 05, 2026				    MPI_INFO_GET_STRING(3)
