This example creates a read-only file named "DOSFDEL.DAT", and then changes the file attributes. It uses DosForceDelete to delete the file so it can not be restored using UNDELETE.

 #define INCL_DOSFILEMGR   /* File Manager values */
 #define INCL_DOSERRORS    /* DOS error values    */
 #include <os2.h>
 #include <stdio.h>

 int main(VOID) {

 UCHAR       uchFileName[]   = "DOSFDEL.DAT";   /* File we want to delete    */
 HFILE       fhDelFile       = 0;               /* File handle from DosOpen  */
 FILESTATUS3 fsts3FileInfo   = {{0}};  /* Information associated with file   */
 ULONG       ulBufferSize    = sizeof(FILESTATUS3); /* File info buffer size */
 ULONG       ulOpenAction    = 0;                 /* Action taken by DosOpen */
 APIRET      rc              = NO_ERROR;          /* Return code             */

                 /* Create a read-only file */

  rc = DosOpen(uchFileName, &fhDelFile,
               &ulOpenAction, 10L, FILE_READONLY,
               OPEN_ACTION_CREATE_IF_NEW | OPEN_ACTION_OPEN_IF_EXISTS,
               OPEN_ACCESS_READWRITE | OPEN_SHARE_DENYNONE, 0L);
  if (rc != NO_ERROR) {
     printf("DosOpen error: return code = %u\n", rc);
     return 1;       }

  rc = DosQueryFileInfo(fhDelFile, FIL_STANDARD,
                        &fsts3FileInfo, ulBufferSize);  /* Get standard info */
  if (rc != NO_ERROR) {
      printf("DosQueryFileInfo error: return code = %u\n", rc);
      return 1;
  } else { printf("File %s created read-only.\n",uchFileName); }

    fsts3FileInfo.attrFile  = FILE_NORMAL;
    rc = DosSetFileInfo(fhDelFile, FIL_STANDARD,
                        &fsts3FileInfo, ulBufferSize);
    if (rc != NO_ERROR) {
        printf("DosSetFileInfo error: return code = %u\n", rc);
        return 1;
    }

    rc = DosClose(fhDelFile);
    /* should check (rc != NO_ERROR) here... */

           /* Delete the file */

    rc = DosForceDelete(uchFileName);
    if (rc != NO_ERROR) {
        printf("DosForceDelete error: return code = %u\n", rc);
        return 1;
    } else {
        printf("File %s has been deleted.\n",uchFileName);
    } /* endif */

   return NO_ERROR;
}