GFORTRAN_UNBUFFERED_PRECONNECTED—Do not buffer I/O on preconnected units ¶The environment variable named GFORTRAN_UNBUFFERED_PRECONNECTED controls
whether I/O on a preconnected unit (i.e. STDOUT or STDERR) is unbuffered. If
the first letter is ‘y’, ‘Y’ or ‘1’, 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.