Quick Start

Your first build

Given a project tree:

└── src
    ├── main.f90
    └── nested-1
        ├── first_dep.f90
        └── nested-2
            └── second_dep.inc

where main.f90 contains a Fortran program that uses nested_1, and first_dep.f90 defines module nested_1 which includes second_dep.inc.

Just run:

fobis build

Legacy command name

The FoBiS.py command is preserved as a backward-compatible alias. Both fobis and FoBiS.py invoke the same tool — existing scripts using FoBiS.py continue to work without changes.

FoBiS.py will:

1. Recursively scan ./ for all Fortran source files
2. Parse each file, extracting use, include, and module statements
3. Resolve the full dependency hierarchy automatically
4. Compile in the correct order (include → module → program)
5. Place compiled objects in ./obj/, module interfaces in ./mod/, and the executable in ./

After the build your tree looks like:

├── main           ← the executable
├── mod/
│   └── nested_1.mod
├── obj/
│   ├── first_dep.o
│   └── main.o
└── src/
    ├── main.f90
    └── nested-1/
        ├── first_dep.f90
        └── nested-2/
            └── second_dep.inc

Customising output directories

Override any directory with CLI flags:

fobis build --obj-dir my-objs --mod-dir my-mods --build-dir my-build

The obj and mod directories are always relative to the build directory, so the tree becomes:

└── my-build/
    ├── my-mods/
    ├── my-objs/
    └── main

Cleaning the project

fobis clean

This removes all compiled objects (*.o) and module files (*.mod) from the obj/ and mod/ directories. If you used custom paths during the build, repeat them:

fobis clean --obj-dir my-objs --mod-dir my-mods --build-dir my-build

Clean only compiled objects (keep executable):

fobis clean --only-obj

Clean only the executable (keep objects for faster incremental rebuild):

fobis clean --only-target

Parsed file extensions

By default FoBiS.py parses files with these extensions:

Category	Extensions
Modern Fortran	.f90 .F90 .f95 .F95 .f03 .F03 .f08 .F08 .f2k .F2K
Legacy Fortran	.f .F .for .FOR .fpp .FPP .fortran .f77 .F77
Include files	.inc .INC .h .H

Add custom include extensions (tab-completable):

fobis build --inc .cmn .icp

Selecting a specific target

Build only one program instead of all programs found:

fobis build -t src/main.f90

With a custom output name:

fobis build -t src/main.f90 -o myapp

Using a fobos configuration file

For anything beyond a one-off build, create a fobos file in the project root. FoBiS.py loads it automatically:

[default]
compiler  = gnu
cflags    = -c -O2
src       = ./src/
build_dir = ./build/
obj_dir   = ./obj/
mod_dir   = ./mod/
target    = src/main.f90
output    = myapp

Then simply:

fobis build
fobis clean

See the fobos section for the full reference.

Quoted string arguments

Flag values that start with - should be prefixed with a leading space to prevent the parser from misinterpreting them as option names:

# problematic:
fobis build --cflags "-c -fPIC"

# correct:
fobis build --cflags " -c -fPIC"