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A work-in-progress collection of Fortran 2008 ISO C binding interfaces to selected POSIX and SysV types, functions, and routines on 64-bit Unix-like operating systems:

• standard input/output,
• file and directory access,
• clocks and timers,
• signals,
• processes,
• pipes,
• serial port input/output,
• terminal control,
• POSIX threads,
• POSIX mutexes and semaphores,
• POSIX regular expressions,
• BSD sockets,
• UNIX System V message queues,
• POSIX message queues.

Similar libraries for modern Fortran:

• M_process,
• M_system,
• forthreads,
• fortran-server,
• fortranposix,
• fortyxima,
• fsockets,
• posix90.

Currently, only Linux (glibc) and FreeBSD are supported. The library has been tested on:

• FreeBSD 14 (GCC 14, LLVM 20),
• Debian 12 (GCC 12, Intel oneAPI 2024).

Preprocessor macros are used to achieve platform-independent interoperability. Therefore, your Fortran compiler has to support at least GNU preprocessor conditionals.

Run either GNU/BSD make or FPM to build the static library libfortran-unix.a. Link your Fortran application with libfortran-unix.a, and optionally with -lpthread to access POSIX threads, or -lrt to access POSIX message queues.

On FreeBSD, run:

$ make freebsd

To build with LLVM 20 instead:

$ make freebsd CC=clang20 FC=flang20

On Linux (x86-64), run:

$ make linux

On Linux (aarch64), run:

$ make linux_aarch64

To build with Intel oneAPI, run:

$ make CC=icx FC=ifx PPFLAGS=

Optionally, install libfortran-unix.a and the associated module files system-wide:

$ make install PREFIX=/opt
--- Installing libfortran-unix.a to /opt/lib/ ...
--- Installing module files to /opt/include/libfortran-unix/ ...

Using FPM, a preprocessor flag has to be passed to GNU Fortran. On FreeBSD:

$ fpm @freebsd-build
$ fpm @freebsd-install

On Linux (x86-64):

$ fpm @linux-amd64-build
$ fpm @linux-amd64-install

On Linux (aarch64):

$ fpm @linux-aarch64-build
$ fpm @linux-aarch64-install

The source code documentation of the library has to be created with FORD. Install the Python package with:

$ python3 -m pip install -U ford

In the source repository, either run:

$ make freebsd_doc

Or:

$ make linux_doc

The HTML files will be written to directory doc/. Open index.html in a web browser.

Examples are provided in directory examples/:

• dirent prints the contents of a file system directory.
• fifo creates a named pipe for IPC.
• fork forks a process and uses anonymous pipes for IPC.
• irc implements a basic IRC bot, based on BSD sockets.
• key reads single key-strokes from standard input.
• mqueue creates a POSIX message queue.
• msg shows message passing with UNIX System V message queues.
• mutex demonstrates threaded access to variable using a mutex.
• os returns the name of the operating system (Linux, macOS, FreeBSD, ...).
• pid outputs the process id.
• pipe creates anonymous pipes for bidirectional IPC.
• pthread runs a Fortran subroutine inside multiple POSIX threads.
• regex calls POSIX regex functions.
• semaphore tests POSIX semaphores.
• serial shows some basic serial port input reading (requires socat(1) and minicom(1)).
• signal catches SIGINT (CTRL + C).
• socket creates a TCP/IP connection to a local netcat server (requires nc(1)).
• stat reads and outputs status of a file.
• time prints out the results of time functions.
• uname prints OS information from uname().
• uptime outputs system uptime.

To compile the example programs, either run:

$ make freebsd_examples

Or:

$ make linux_examples

ISC