3 Runtime: Influencing runtime behavior with environment variables

The behavior of the gfortran can be influenced by environment variables.

Malformed environment variables are silently ignored.

• TMPDIR:		Directory for scratch files
• GFORTRAN_STDIN_UNIT:		Unit number for standard input
• GFORTRAN_STDOUT_UNIT:		Unit number for standard output
• GFORTRAN_STDERR_UNIT:		Unit number for standard error
• GFORTRAN_UNBUFFERED_ALL:		Do not buffer I/O for all units.
• GFORTRAN_UNBUFFERED_PRECONNECTED:		Do not buffer I/O for preconnected units.
• GFORTRAN_SHOW_LOCUS:		Show location for runtime errors
• GFORTRAN_OPTIONAL_PLUS:		Print leading + where permitted
• GFORTRAN_DEFAULT_RECL:		Default record length for new files
• GFORTRAN_LIST_SEPARATOR:		Separator for list output
• GFORTRAN_CONVERT_UNIT:		Set endianness for unformatted I/O
• GFORTRAN_ERROR_BACKTRACE:		Show backtrace on run-time errors