gfortran: add page (#9854)

pages/common/gfortran.md

@@ -0,0 +1,24 @@
+# gfortran
+
+> Preprocess and compile Fortran source files, then assemble and link them together.
+> More information: <https://gcc.gnu.org/wiki/GFortran>.
+
+- Compile multiple source files into an executable:
+
+`gfortran {{path/to/source1.f90 path/to/source2.f90 ...}} -o {{path/to/output_executable}}`
+
+- Show common warnings, debug symbols in output, and optimize without affecting debugging:
+
+`gfortran {{path/to/source.f90}} -Wall -g -Og -o {{path/to/output_executable}}`
+
+- Include libraries from a different path:
+
+`gfortran {{path/to/source.f90}} -o {{path/to/output_executable}} -I{{path/to/mod_and_include}} -L{{path/to/library}} -l{{library_name}}`
+
+- Compile source code into Assembler instructions:
+
+`gfortran -S {{path/to/source.f90}}`
+
+- Compile source code into an object file without linking:
+
+`gfortran -c {{path/to/source.f90}}`