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.TH "MPI_INFO_GET" "3" "May 30, 2025" "" "Open MPI"
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\fI\%MPI_Info_get\fP — Retrieves the value associated with a key in an info
object.
.SH SYNTAX
.SS C Syntax
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.INDENT 3.5
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.nf
.ft C
#include <mpi.h>

int MPI_Info_get(MPI_Info info, const char *key, int valuelen, char *value, int *flag)
.ft P
.fi
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.SS Fortran Syntax
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.INDENT 3.5
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.nf
.ft C
USE MPI
! or the older form: INCLUDE \(aqmpif.h\(aq
MPI_INFO_GET(INFO, KEY, VALUELEN, VALUE, FLAG, IERROR)
     INTEGER INFO, VALUELEN, IERROR
     CHARACTER*(*) KEY, VALUE
     LOGICAL FLAG
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.fi
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.SS Fortran 2008 Syntax
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.nf
.ft C
USE mpi_f08
MPI_Info_get(info, key, valuelen, value, flag, ierror)
     TYPE(MPI_Info), INTENT(IN) :: info
     CHARACTER(LEN=*), INTENT(IN) :: key
     INTEGER, INTENT(IN) :: valuelen
     CHARACTER(LEN=valuelen), INTENT(OUT) :: value
     LOGICAL, INTENT(OUT) :: flag
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror
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.fi
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.SH INPUT PARAMETERS
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.IP \(bu 2
\fBinfo\fP: Info object (handle).
.IP \(bu 2
\fBkey\fP: Key (string).
.IP \(bu 2
\fBvaluelen\fP: Length of value arg (integer).
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.SH OUTPUT PARAMETER
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.IP \(bu 2
\fBvalue\fP: Value (string).
.IP \(bu 2
\fBflag\fP: Returns true if key defined, false if not (boolean).
.IP \(bu 2
\fBierror\fP: Fortran only: Error status (integer).
.UNINDENT
.SH DESCRIPTION
.sp
\fI\%MPI_Info_get\fP retrieves the value associated with \fIkey\fP in a previous
call to \fI\%MPI_Info_set\fP\&. If such a key exists, it sets \fIflag\fP to true and
returns the value in \fIvalue\fP; otherwise it sets \fIflag\fP to false and
leaves \fIvalue\fP unchanged. \fIvaluelen\fP is the number of characters
available in value. If it is less than the actual size of the value, the
returned value is truncated. In C, \fIvaluelen\fP should be one less than
the amount of allocated space to allow for the null terminator.
.sp
If \fIkey\fP is larger than MPI_MAX_INFO_KEY, the call is erroneous.
.SH ERRORS
.sp
Almost all MPI routines return an error value; C routines as the return result
of the function and Fortran routines in the last argument.
.sp
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
\fI\%MPI_Init\fP/\fI\%MPI_Init_thread\fP, after \fI\%MPI_Finalize\fP, or when using the Sessions
Model exclusively) the error raises the initial error handler. The initial
error handler can be changed by calling \fI\%MPI_Comm_set_errhandler\fP on
MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI
argument to mpiexec or info key to \fI\%MPI_Comm_spawn\fP/\fI\%MPI_Comm_spawn_multiple\fP\&.
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.
.sp
Open MPI includes three predefined error handlers that can be used:
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.IP \(bu 2
\fBMPI_ERRORS_ARE_FATAL\fP
Causes the program to abort all connected MPI processes.
.IP \(bu 2
\fBMPI_ERRORS_ABORT\fP
An error handler that can be invoked on a communicator,
window, file, or session. When called on a communicator, it
acts as if \fI\%MPI_Abort\fP was called on that communicator. If
called on a window or file, acts as if \fI\%MPI_Abort\fP 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.
.IP \(bu 2
\fBMPI_ERRORS_RETURN\fP
Returns an error code to the application.
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MPI applications can also implement their own error handlers by calling:
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.IP \(bu 2
\fI\%MPI_Comm_create_errhandler\fP then \fI\%MPI_Comm_set_errhandler\fP
.IP \(bu 2
\fI\%MPI_File_create_errhandler\fP then \fI\%MPI_File_set_errhandler\fP
.IP \(bu 2
\fI\%MPI_Session_create_errhandler\fP then \fI\%MPI_Session_set_errhandler\fP or at \fI\%MPI_Session_init\fP
.IP \(bu 2
\fI\%MPI_Win_create_errhandler\fP then \fI\%MPI_Win_set_errhandler\fP
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Note that MPI does not guarantee that an MPI program can continue past
an error.
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See the \fI\%MPI man page\fP for a full list of \fI\%MPI error codes\fP\&.
.sp
See the Error Handling section of the MPI\-3.1 standard for
more information.
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\fBSEE ALSO:\fP
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.INDENT 3.5
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.IP \(bu 2
\fI\%MPI_Info_create\fP
.IP \(bu 2
\fI\%MPI_Info_delete\fP
.IP \(bu 2
\fI\%MPI_Info_dup\fP
.IP \(bu 2
\fI\%MPI_Info_free\fP
.IP \(bu 2
\fI\%MPI_Info_get_valuelen\fP
.IP \(bu 2
\fI\%MPI_Info_get_nkeys\fP
.IP \(bu 2
\fI\%MPI_Info_get_nthkey\fP
.IP \(bu 2
\fI\%MPI_Info_set\fP
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.UNINDENT
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.SH COPYRIGHT
2003-2025, The Open MPI Community
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