Specify directory where gfortran should look for modules

module fortran gfortran
astay13 picture astay13 · Jan 13, 2012 · Viewed 19.5k times · Source

I currently compile programs based on modules (such as main program foo which depends on module bar) as follows:

gfortran -c bar.f90
gfortran -o foo.exe foo.f90 bar.o

This works fine when foo.f90 and bar.f90 are in the same directory. How do I specify a directory where gfortran should look for bar.o when I call use bar in foo.f90? (i.e. I don't want to specify that the compiler should link bar.o specifically, I just want it to go find it.)

Answer

Chris picture Chris · Jan 16, 2012

You can tell gfortran where your module files (.mod files) are located with the -I compiler flag. In addition, you can tell the compiler where to put compiled modules with the -J compiler flag. See the section "Options for directory search" in the gfortran man page.

I use these to place both my object (.o files) and my module files in the same directory, but in a different directory to all my source files, so I don't clutter up my source directory. For example,

SRC = /path/to/project/src
OBJ = /path/to/project/obj
BIN = /path/to/project/bin

gfortran -J$(OBJ) -c $(SRC)/bar.f90 -o $(OBJ)/bar.o
gfortran -I$(OBJ) -c $(SRC)/foo.f90 -o $(OBJ)/foo.o
gfortran -o $(BIN)/foo.exe $(OBJ)/foo.o $(OBJ)/bar.o

While the above looks like a lot of effort to type out on the command line, I generally use this idea in my makefiles.

Just for reference, the equivalent Intel fortran compiler flags are -I and -module. Essentially ifort replaces the -J option with -module. Note that there is a space after module, but not after J.

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