3.6 GFORTRAN_UNBUFFERED_ALL—Don't buffer I/O on all units

This environment variable controls whether all I/O is unbuffered. If the first letter is `y', `Y' or `1', all I/O is unbuffered. This will slow down small sequential reads and writes. If the first letter is `n', `N' or `0', I/O is buffered. This is the default.