Lahey/GNU Fortran

Running GFortran Directly

Running tools

The installation contains 32 bit compiler applications named gfortran.exe and gcc.exe among other tools that can generate both 32 bit and 64 bit executables capable of running in parallel on multiple processors. A brief synopsis of tool operation can be obtained by opening a console with the compiler on the path and typing the tool name with the option --help.

Note - when building an application, if no output executable file is specified, the executable will be named "a.exe"

For more information on gfortran, see The GNU Fortran compiler.

Getting Help

A comprehensive synopsis of compiler options can be obtained using one of the GFortran options --help=fortran --help=optimize --help=target --help=params

Application Target Architecture

When compiling or linking, specify the -m64 or the -m32 option to build a 64-bit application or a 32-bit application, respectively.


The installation contains 32-bit and 64-bit debuggers as separate applications. In order to debug a 32 bit executable, you must use the 32 bit debugger, gdb32.exe. To debug a 64 bit executable, use gdb64.exe.


Lahey has made a few changes to the runtime environment that affects how GFortran is linked:

Copies of the modified source code are provided in the src installation directory.