Make is indispensable for managing large programs,
but is useful for smaller programs as well.
As an example, consider a program consisting of the files
main.f, file1.f, and file2.f.
Here is a sample makefile to take these three files and generate an
executable called main.
OBJ = main.o file1.o file2.o .f.o: f77 -c $< main: $(OBJ) f77 -o main $(OBJ)
.f.o: and main: begin with a TAB character.
This makefile is executed by the command make main.
First make ensures that all the files
after main: exist.
If any do not exist, make looks
for a rule to create it. In this case, the lines after .f.o
tell it how to make a .o file from a .f file.
Once all the appropriate .o files exist, make runs
f77 -o main $(OBJ) to create the executable.
Make also compares the modification time of the .f file with
that of the
.o file. If the .f file has been modified since it was last compiled,
make will recompile the
.f file.
In this example, suppose main.f had been modified.
Make would recompile main.f, but not file1.f
or file2.f .
main.f and file1.f include a file
param.h and that we would like these files recompiled if
it changes.
Add the line
main.o file1.o: param.hto the end of the makefile.