MPI_FILE_GET_POSITION(3)

💖 MPI_FILE_GET_POSITION(3) 💖

okay bestie, so this one lives in the Open MPI manual, section 3, and it's all about finding out exactly where your individual file pointer is sitting rn. like a little "you are here" map but for your file. iconic.

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✨ NAME ✨

MPI_File_get_position — Returns the current position of the individual file pointer.

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🌸 SYNTAX 🌸

C Syntax

#include <mpi.h>

int MPI_File_get_position(MPI_File fh, MPI_Offset *offset)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_GET_POSITION(FH, OFFSET, IERROR)
     INTEGER FH, IERROR
     INTEGER(KIND=MPI_OFFSET_KIND)   OFFSET

Fortran 2008 Syntax

USE mpi_f08
MPI_File_get_position(fh, offset, ierror)
     TYPE(MPI_File), INTENT(IN) :: fh
     INTEGER(KIND=MPI_OFFSET_KIND), INTENT(OUT) :: offset
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🫶 INPUT PARAMETER 🫶

• fh — File handle (handle). like, the lil ticket that says which file we're chatting about.

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👑 OUTPUT PARAMETERS 👑

• offset — Offset of the individual file pointer (integer). this is the answer bestie, the whole reason we're here.
• ierror — Fortran only: Error status (integer).

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🦋 DESCRIPTION 🦋

MPI_File_get_position returns, in offset, the current position of the individual file pointer — measured in etype units, relative to the current displacement and file type. so it's not just "byte 4002", it's etype units, no cap. periodt.

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💀 ERRORS 💀

So basically almost every MPI routine hands you back an error value. In C it comes back as the return result of the function, and in Fortran it lands in that last argument. ok.

Before that error value gets returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. And if there's no communication object associated with the MPI call? Then the call is considered attached to MPI_COMM_SELF and it'll call the associated MPI error handler instead. The way that works:

When MPI_COMM_SELF is not initialized (i.e., before MPI_Init / MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. And that initial error handler can be changed by:

• calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or
• the mpi_initial_errhandler CLI argument to mpiexec, or
• the info key to MPI_Comm_spawn / 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 ships with three predefined error handlers you can use, and they are:

• MPI_ERRORS_ARE_FATAL — Causes the program to abort all connected MPI processes. 💀 genuinely fatal, bestie.
• 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 was called on that communicator. If called on a window or file, acts as if 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 then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler

Note that MPI does not guarantee that an MPI program can continue past an error. like, do not assume you can just keep vibing after an error, because you might not be able to. 🚨

See the MPI man page for a full list of MPI error codes.

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

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🎀 Copyright 🎀

2003-2026, The Open MPI Community

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and that's the whole thing, you ate that 🍓 mwah 💅 — this lil gem is from the Open MPI manual and it's dated Sep 10, 2026. go get your file position bestie, you got this 🦋✨