g77 - GNU project Fortran Compiler (v0.5.24)

g77 [c option | filename ]...

The information in this man page is an extract from the full documentation of the GNU Fortran compiler (version 0.5.24), and is limited to the meaning of some of the options.

This man page is not up to date, since no volunteers want to maintain it. If you find a discrepancy between the man page and the software, please check the Info file, which is the authoritative documentation.

If we find that the things in this man page that are out of date cause significant confusion or complaints, we will stop distributing the man page. The alternative, updating the man page when we update the Info file, is impractical because the rest of the work of maintaining GNU Fortran leaves us no time for that. The GNU project regards man pages as obsolete and should not let them take time away from other things.

For complete and current documentation, refer to the Info file `c g77c ' or the manual Using and Porting GNU Fortran (for version 0.5.24)c . Both are made from the Texinfo source file g77.texi.

If your system has the `c infoc ' command installed, the command `c info g77c ' should work, unless g77 has not been properly installed. If your system lacks `c infoc ', or you wish to avoid using it for now, the command `c more /usr/info/g77.info*c ' should work, unless g77 has not been properly installed.

If g77 has not been properly installed, so that you cannot easily access the Info file for it, ask your system administrator, or the installer of g77 (if you know who that is) to fix the problem.

The C and F77 compilers are integrated; g77 is a program to call gcc with options to recognize programs written in Fortran (ANSI FORTRAN 77, also called F77). gcc processes input files through one or more of four stages: preprocessing, compilation, assembly, and linking. This man page contains full descriptions for only F77-specific aspects of the compiler, though it also contains summaries of some general-purpose options. For a fuller explanation of the compiler, see gcc(1).

For complete documentation on GNU Fortran, type `c info g77c '.

F77 source files use the suffix `c .fc ', `c .forc ', or `c .FORc '; F77 files to be preprocessed by cpp(1) use the suffix `c .Fc ', `c .fppc ', or `c .FPPc '; Ratfor source files use the suffix `c .rc ' (though ratfor itself is not supplied as part of g77c ).

There are many command-line options, including options to control details of optimization, warnings, and code generation, which are common to both gcc and g77c . For full information on all options, see gcc(1).

Options must be separate: `c -drc ' is quite different from `c -d -r '.

Most `c -fc ' and `c -Wc ' options have two contrary forms: -fname and -fno-namec (or -Wname and -Wno-namec ). Only the non-default forms are shown here.

-c

Compile or assemble the source files, but do not link. The compiler output is an object file corresponding to each source file.

-Dmacro

Define macro c macroc with the string `c 1c ' as its definition.

-Dmacro=defn

Define macro c macroc as c defnc .

-E

Stop after the preprocessing stage; do not run the compiler proper. The output is preprocessed source code, which is sent to the standard output.

-g

Produce debugging information in the operating system's native format (for DBX or SDB or DWARF). GDB also can work with this debugging information. On most systems that use DBX format, `c -gc ' enables use of extra debugging information that only GDB can use.

Unlike most other Fortran compilers, GNU Fortran allows you to use `c -gc ' with `c -Oc '. The shortcuts taken by optimized code may occasionally produce surprising results: some variables you declared may not exist at all; flow of control may briefly move where you did not expect it; some statements may not be executed because they compute constant results or their values were already at hand; some statements may execute in different places because they were moved out of loops.

Nevertheless it proves possible to debug optimized output. This makes it reasonable to use the optimizer for programs that might have bugs.

-Idirc

Append directory c dirc to the list of directories searched for include files.

-Ldirc

Add directory c dirc to the list of directories to be searched for `c -lc '.

-llibraryc

Use the library named c libraryc when linking.

-nostdinc

Do not search the standard system directories for header files. Only the directories you have specified with -I options (and the current directory, if appropriate) are searched.

-O

Optimize. Optimizing compilation takes somewhat more time, and a lot more memory for a large function. See the GCC documentation for further optimisation options. Loop unrolling, in particular, may be worth investigating for typical numerical Fortran programs.

-o filec

Place output in file c filec .

-S

Stop after the stage of compilation proper; do not assemble. The output is an assembler code file for each non-assembler input file specified.

-Umacro

Undefine macro c macroc .

-v

Print (on standard error output) the commands executed to run the stages of compilation. Also print the version number of the compiler driver program and of the preprocessor and the compiler proper. The version numbers of g77 itself and the GCC distribution on which it is based are distinct.

-Wall

Issue warnings for conditions which pertain to usage that we recommend avoiding and that we believe is easy to avoid, even in conjunction with macros.

file.h C header (preprocessor) file

file.f Fortran source file

file.for Fortran source file

file.FOR Fortran source file

file.F preprocessed Fortran source file

file.fpp preprocessed Fortran source file

file.FPP preprocessed Fortran source file

file.r Ratfor source file (ratfor not included)

file.s assembly language file

file.o object file

a.out link edited output

TMPDIR/cc temporary files

LIBDIR/cpp preprocessor

LIBDIR/f771 compiler

LIBDIR/libg2c.a Fortran run-time library

LIBDIR/libgcc.a GCC subroutine library

/lib/crt[01n].o start-up routine

/lib/libc.a standard C library, see intro(3)

/usr/include standard directory for #include files

LIBDIR/include standard gcc directory for #include

files. LIBDIR is usually /usr/local/lib/c machine/version. TMPDIR comes from the environment variable TMPDIR (default /usr/tmp if available, else /tmpc ).

gcc(1), cpp(1), as(1), ld(1), gdb(1), adb(1), dbx(1), sdb(1).

`g77', `gcc', `cpp', `as', `ld', and `gdb' entries in infoc .

Using and Porting GNU Fortran (for version 0.5.24)c , James Craig Burley; Using and Porting GNU CC (for version 2.0)c , Richard M. Stallman; The C Preprocessorc , Richard M. Stallman; Debugging with GDB: the GNU Source-Level Debuggerc , Richard M. Stallman and Roland H. Pesch; Using as: the GNU Assemblerc , Dean Elsner, Jay Fenlason & friends; gld: the GNU linkerc , Steve Chamberlain and Roland Pesch.

For instructions on how to report bugs, type `c info g77 -n Bugsc '.

Copyright (c) 1991-1998 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.

See the GNU CC Manual for the contributors to GNU CC. See the GNU Fortran Manual for the contributors to GNU Fortran.