## 9.2.7. Querying File Parameters

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MPI_FILE_GET_GROUP(fh, group)
IN fh | file handle (handle)
OUT group | group which opened the file (handle)

`int MPI_File_get_group(MPI_File fh, MPI_Group *group)
` `MPI_FILE_GET_GROUP(FH, GROUP, IERROR)
INTEGER FH, GROUP, IERROR
` `MPI::Group MPI::File::Get_group() const
`

MPI_FILE_GET_GROUP returns a duplicate of the group of the communicator used to open the file associated with fh. The group is returned in group. The user is responsible for freeing group.

MPI_FILE_GET_AMODE(fh, amode)
IN fh | file handle (handle)
OUT amode | file access mode used to open the file (integer)

`int MPI_File_get_amode(MPI_File fh, int *amode)
` `MPI_FILE_GET_AMODE(FH, AMODE, IERROR)
INTEGER FH, AMODE, IERROR
` `int MPI::File::Get_amode() const
`

MPI_FILE_GET_AMODE returns, in amode, the access mode of the file associated with fh.

Example In Fortran 77, decoding an amode bit vector will require a routine such as the following:

          SUBROUTINE BIT_QUERY(TEST_BIT, MAX_BIT, AMODE, BIT_FOUND)
    !
    !   TEST IF THE INPUT TEST_BIT IS SET IN THE INPUT AMODE
    !   IF SET, RETURN 1 IN BIT_FOUND, 0 OTHERWISE
    !
          INTEGER TEST_BIT, AMODE, BIT_FOUND, CP_AMODE, HIFOUND
          BIT_FOUND = 0
          CP_AMODE = AMODE
     100  CONTINUE
          LBIT = 0
          HIFOUND = 0
          DO 20 L = MAX_BIT, 0, -1
             MATCHER = 2**L
             IF (CP_AMODE .GE. MATCHER .AND. HIFOUND .EQ. 0) THEN
                HIFOUND = 1
                LBIT = MATCHER
                CP_AMODE = CP_AMODE - MATCHER
             END IF
      20  CONTINUE
          IF (HIFOUND .EQ. 1 .AND. LBIT .EQ. TEST_BIT) BIT_FOUND = 1
          IF (BIT_FOUND .EQ. 0 .AND. HIFOUND .EQ. 1 .AND. &
              CP_AMODE .GT. 0) GO TO 100
          END

This routine could be called successively to decode amode, one bit at a time. For example, the following code fragment would check for MPI_MODE_RDONLY.

          CALL BIT_QUERY(MPI_MODE_RDONLY, 30, AMODE, BIT_FOUND)
          IF (BIT_FOUND .EQ. 1) THEN
             PRINT *, ' FOUND READ-ONLY BIT IN AMODE=', AMODE
          ELSE
             PRINT *, ' READ-ONLY BIT NOT FOUND IN AMODE=', AMODE
          END IF

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MPI-2.0 of July 18, 1997
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