### 3.6 `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.