Darshan does not catch files opened with mkostemp()
The glibc mkostemp() function does not call the libc open() or create() calls, it instead issues an open64 system call directly at least in glibc 2.15.
This causes it to bypass the existing Darshan wrappers for open, and Darshan will not record any activity to that file.
This probably means that we need to add new wrappers for mkostemp (and its related functions, see man page). Need to check glibc implementation to confirm.