TMPDIR—Directory for scratch files
When opening a file with
STATUS='SCRATCH', GNU Fortran tries to
create the file in one of the potential directories by testing each
directory in the order below.
TMPDIR, if it exists.
GetTempPathfunction. Alternatively, on the Cygwin target, the
TEMPenvironment variables, if they exist, in that order.
P_tmpdirmacro if it is defined, otherwise the directory /tmp.