fbc command-line

Using the fbc command-line.
The official FreeBASIC distribution comes with fbc, FreeBASIC's flagship compiler. fbc is a command line compiler, and can be launched from the console - from DOS, the Windows command prompt or a Linux shell. Running fbc from the console without any arguments displays a list of available options, or command-line switches, that can be used to adjust the behavior of the compiler.

At its simplest, fbc takes a source file as a command-line argument and produces an executable file. It does this by compiling the source file (.bas) into an assembly (.asm) file, then compiling this into an object file (.o) using GAS and finally linking using LD this object file to other object files and libraries it needs to run, producing the final executable file. The assembly and compiled object files are deleted at this point by default. For example, the following command,

fbc foo.bas

produces the executable foo.exe in DOS and Windows, and ./foo in Linux. fbc can accept multiple source files at once, compile and link them all into one executable. For example, the following command,

fbc foo.bas bar.bas baz.bas

produces the executable foo.exe in DOS and Windows, and ./foo in Linux. Since foo.bas was listed first, it will be the main entry point into the executable, and also provide its name. To specify a different entry point or executable name, use the "-m" and "-x" switches, respectively. To have, for example, baz.bas provide the main entry point into an executable called foobar.exe, you would use

fbc -x foobar.exe -m baz foo.bas bar.bas baz.bas

The "-x" switch names the executable verbatim, so in Linux, the executable produced from the above command would be called ./foobar.exe.

fbc [ options ] [ input_list ]

Where input_list is a list of filenames. Accepted files are:

File extension Description
.bas FreeBASIC source file
.a Library
.o Object file
.rc Resource script (Windows only)
.res Compiled resource (Windows only)
.xpm X icon pixmap (Linux only)

Source code
-b < name >
Add a source file to compilation
-i < name >
Add a path to search for include files
-include < name >
Include a header file on each source compiled
-d < name=val >
Add a preprocessor's define
-lang < name >
Select language mode: fb, fblite, qb, deprecated
-forcelang < name >
Select language mode: fb, fblite, qb, deprecated (overides statements in code)

Code generation
-target < platform >
Set the target platform for cross compilation
-gen < backend >
Sets the compiler backend (default is 'gas').
-asm < format >
Sets the assembler format for Asm block.
-arch < type >
Set target architecture (default: 486)
-O < level >
Set the optimization level (-gen gcc).
-vec < level >
Set level of vector optimizations enabled by the compiler (default: 0)
-fpu < type >
Set the floating point arithmetics unit (default: FPU)
-fpmode < type >
Select between fast and accurate floating-point operations (default: PRECISE)
-z < value >
Sets miscellaneous or experimental options.

-m < name >
Main file without extension, the entry point (default is the first .bas file on the command line)
Add debug info
Enable function profiling
Add error checking
Add error checking with RESUME support
Same as -ex plus array bounds and null-pointer checking
-Wa < opt >
Pass options to GAS (separated by commas)
-Wc < opt >
Pass options to GCC (separated by commas)
-o < name >
Set object file path/name (must be passed after the .bas file)

-a < name >
Add an object file to linker's list
-l < name >
Add a library file to linker's list
-p < name >
Add a path to search for libraries
Link with thread-safe runtime library
Do not include the default libraries
Prefer static libraries over dynamic ones when linking
-map < name >
Save the linking map to file name
-Wl < opt >
Pass options to LD (separated by commas)
Export symbols for dynamic linkage
Create a static library
Create a DLL, including the import library
Create a DLL, including the import library. (Same as -dylib)
-x < name >
Set executable/library path/name

-prefix < path >
Set the compiler prefix path
Show compiler version on the command line, do not compile or link.
Be verbose
-print < option >
Display certain information (host, target, etc.)
Emit the preprocessed input file only, do not compile
Compile into intermediate file(s) only, do not assemble or link
Compile into asm file(s) only, do not assemble or link
Compile and assemble source file only, do not link
Do not delete the intermediate file(s)
Do not delete the asm file(s)
Do not delete the object file(s)
-w < value >
Set min warning level: all, pedantic, next or a value
-maxerr < val >
Only stop parsing if <val> errors occurred
Do not show source line where error occurred

Target specific
-s < name >
Set subsystem (gui, console)
-t < value >
Set stack size in kbytes (default: 1M)

@< file >
Read (additional) command-line options from a file


fbc myfile.bas
(With DOS version of FBC, compile and link a DOS executable MYFILE.EXE.)
fbc -s gui myfile.bas
(With Windows version of FBC, compile and link a Windows executable myfile.exe. Running the program will not show the console window ("MS-DOS Prompt"))
fbc -lib module1.bas module2.bas module3.bas -x libmylib.a
(Compile and link a static library libmylib.a from the three source files)
fbc -m main_module -c main_module.bas
(Compile an object file main_module.o and mark it as an entry point)
fbc -c sub_module.bas
(Compile an object file sub_module.o)
fbc -x application.exe main_module.o sub_module.o
(Link an executable application.exe)

Note: How to include an icon in a FB executable program
There is a simple command line option to compile a FB program into an executable with an Icon:
  • Create a *.rc file, for example appicon.rc, with this info:
  • FB_PROGRAM_ICON ICON "appicon.ico"
    (where appicon.ico is the name of icon)
  • Then when compiling program, add appicon.rc in the list of files to compile.

See also:
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