1 @c Copyright (C) 2004, 2005
2 @c Free Software Foundation, Inc.
3 @c This is part of the GFORTRAN manual.
4 @c For copying conditions, see the file gfortran.texi.
8 Copyright @copyright{} 2004, 2005
9 Free Software Foundation, Inc.
11 Permission is granted to copy, distribute and/or modify this document
12 under the terms of the GNU Free Documentation License, Version 1.2 or
13 any later version published by the Free Software Foundation; with the
14 Invariant Sections being ``GNU General Public License'' and ``Funding
15 Free Software'', the Front-Cover texts being (a) (see below), and with
16 the Back-Cover Texts being (b) (see below). A copy of the license is
17 included in the gfdl(7) man page.
19 (a) The FSF's Front-Cover Text is:
23 (b) The FSF's Back-Cover Text is:
25 You have freedom to copy and modify this GNU Manual, like GNU
26 software. Copies published by the Free Software Foundation raise
27 funds for GNU development.
29 @c Set file name and title for the man page.
31 @settitle GNU Fortran 95 compiler.
33 gfortran [@option{-c}|@option{-S}|@option{-E}]
34 [@option{-g}] [@option{-pg}] [@option{-O}@var{level}]
35 [@option{-W}@var{warn}@dots{}] [@option{-pedantic}]
36 [@option{-I}@var{dir}@dots{}] [@option{-L}@var{dir}@dots{}]
37 [@option{-D}@var{macro}[=@var{defn}]@dots{}] [@option{-U}@var{macro}]
38 [@option{-f}@var{option}@dots{}]
39 [@option{-m}@var{machine-option}@dots{}]
40 [@option{-o} @var{outfile}] @var{infile}@dots{}
42 Only the most useful options are listed here; see below for the
46 gpl(7), gfdl(7), fsf-funding(7),
47 cpp(1), gcov(1), gcc(1), as(1), ld(1), gdb(1), adb(1), dbx(1), sdb(1)
48 and the Info entries for @file{gcc}, @file{cpp}, @file{gfortran}, @file{as},
49 @file{ld}, @file{binutils} and @file{gdb}.
52 For instructions on reporting bugs, see
53 @w{@uref{http://gcc.gnu.org/bugs.html}}.
56 See the Info entry for @command{gfortran} for contributors to GCC and
61 @node Invoking GFORTRAN
62 @chapter GNU Fortran 95 Command Options
63 @cindex GNU Fortran 95 command options
64 @cindex command options
65 @cindex options, GNU Fortran 95 command
67 @c man begin DESCRIPTION
69 The @command{gfortran} command supports all the options supported by the
70 @command{gcc} command. Only options specific to gfortran are documented here.
72 @xref{Invoking GCC,,GCC Command Options,gcc,Using the GNU Compiler
73 Collection (GCC)}, for information
74 on the non-Fortran-specific aspects of the @command{gcc} command (and,
75 therefore, the @command{gfortran} command).
77 @cindex options, negative forms
78 @cindex negative forms of options
79 All @command{gcc} and @command{gfortran} options
80 are accepted both by @command{gfortran} and by @command{gcc}
81 (as well as any other drivers built at the same time,
82 such as @command{g++}),
83 since adding @command{gfortran} to the @command{gcc} distribution
84 enables acceptance of @command{gfortran} options
85 by all of the relevant drivers.
87 In some cases, options have positive and negative forms;
88 the negative form of @option{-ffoo} would be @option{-fno-foo}.
89 This manual documents only one of these two forms, whichever
90 one is not the default.
94 * Option Summary:: Brief list of all @command{gfortran} options,
96 * Fortran Dialect Options:: Controlling the variant of Fortran language
98 * Warning Options:: How picky should the compiler be?
99 * Debugging Options:: Symbol tables, measurements, and debugging dumps.
100 * Directory Options:: Where to find module files
101 * Code Gen Options:: Specifying conventions for function calls, data layout
103 * Environment Variables:: Env vars that affect GNU Fortran.
107 @section Option Summary
111 Here is a summary of all the options specific to GNU Fortran, grouped
112 by type. Explanations are in the following sections.
115 @item Fortran Language Options
116 @xref{Fortran Dialect Options,,Options Controlling Fortran Dialect}.
118 -ffree-form -fno-fixed-form @gol
119 -fdollar-ok -fimplicit-none -fmax-identifier-length @gol
120 -std=@var{std} -fd-lines-as-code -fd-lines-as-comments @gol
121 -ffixed-line-length-@var{n} -ffixed-line-length-none @gol
122 -fdefault-double-8 -fdefault-integer-8 -fdefault-real-8 @gol
125 @item Warning Options
126 @xref{Warning Options,,Options to Request or Suppress Warnings}.
128 -fsyntax-only -pedantic -pedantic-errors @gol
129 -w -Wall -Waliasing -Wconversion @gol
130 -Wimplicit-interface -Wnonstd-intrinsics -Wsurprising -Wunderflow @gol
131 -Wunused-labels -Wline-truncation -W}
133 @item Debugging Options
134 @xref{Debugging Options,,Options for Debugging Your Program or GCC}.
136 -fdump-parse-tree -ffpe-trap=@var{list}}
138 @item Directory Options
139 @xref{Directory Options,,Options for Directory Search}.
141 -I@var{dir} -M@var{dir}}
143 @item Code Generation Options
144 @xref{Code Gen Options,,Options for Code Generation Conventions}.
146 -fno-automatic -ff2c -fno-underscoring -fsecond-underscore @gol
147 -fbounds-check -fmax-stack-var-size=@var{n} @gol
148 -fpackderived -frepack-arrays -fshort-enums}
152 * Fortran Dialect Options:: Controlling the variant of Fortran language
154 * Warning Options:: How picky should the compiler be?
155 * Debugging Options:: Symbol tables, measurements, and debugging dumps.
156 * Directory Options:: Where to find module files
157 * Code Gen Options:: Specifying conventions for function calls, data layout
161 @node Fortran Dialect Options
162 @section Options Controlling Fortran Dialect
163 @cindex dialect options
164 @cindex language, dialect options
165 @cindex options, dialect
167 The following options control the dialect of Fortran
168 that the compiler accepts:
171 @cindex -ffree-form option
172 @cindex options, -ffree-form
173 @cindex -fno-fixed-form option
174 @cindex options, -fno-fixed-form
175 @cindex source file format
179 @cindex Fortran 90, features
182 Specify the layout used by the source file. The free form layout
183 was introduced in Fortran 90. Fixed form was traditionally used in
184 older Fortran programs.
186 @cindex option, -fd-lines-as-code
187 @cindex -fd-lines-as-code, option
188 @cindex option, -fd-lines-as-comments
189 @cindex -fd-lines-as-comments, option
190 @item -fd-lines-as-code
191 @item -fd-lines-as-comment
192 Enables special treating for lines with @samp{d} or @samp{D} in fixed
193 form sources. If the @option{-fd-lines-as-code} option is given
194 they are treated as if the first column contained a blank. If the
195 @option{-fd-lines-as-comments} option is given, they are treated as
198 @cindex option, -fdefault-double-8
199 @cindex -fdefault-double-8, option
200 @item -fdefault-double-8
201 Set the "DOUBLE PRECISION" type to an 8 byte wide.
203 @cindex option, -fdefault-integer-8
204 @cindex -fdefault-integer-8, option
205 @item -fdefault-integer-8
206 Set the default integer and logical types to an 8 byte wide type.
207 Do nothing if this is already the default.
209 @cindex option, -fdefault-real-8
210 @cindex -fdefault-real-8, option
211 @item -fdefault-real-8
212 Set the default real type to an 8 byte wide type.
213 Do nothing if this is already the default.
215 @cindex -fdollar-ok option
216 @cindex options, -fdollar-ok
220 @cindex character set
221 Allow @samp{$} as a valid character in a symbol name.
223 @cindex -fno-backslash option
224 @cindex options, -fno-backslash
227 @cindex escape characters
228 Compile switch to change the interpretation of a backslash from
229 ``C''-style escape characters to a single backslash character.
231 @cindex -ffixed-line-length-@var{n} option
232 @cindex options, -ffixed-line-length-@var{n}
233 @item -ffixed-line-length-@var{n}
234 @cindex source file format
235 @cindex lines, length
236 @cindex length of source lines
238 @cindex limits, lengths of source lines
239 Set column after which characters are ignored in typical fixed-form
240 lines in the source file, and through which spaces are assumed (as
241 if padded to that length) after the ends of short fixed-form lines.
244 @cindex extended-source option
245 Popular values for @var{n} include 72 (the
246 standard and the default), 80 (card image), and 132 (corresponds
247 to ``extended-source'' options in some popular compilers).
248 @var{n} may be @samp{none}, meaning that the entire line is meaningful
249 and that continued character constants never have implicit spaces appended
250 to them to fill out the line.
251 @option{-ffixed-line-length-0} means the same thing as
252 @option{-ffixed-line-length-none}.
254 @cindex -fmax-identifier-length=@var{n} option
255 @cindex option -fmax-identifier-length=@var{n}
256 @item -fmax-identifier-length=@var{n}
257 Specify the maximum allowed identifier length. Typical values are
258 31 (Fortran 95) and 63 (Fortran 200x).
260 @cindex -fimplicit-none option
261 @cindex options, -fimplicit-none
262 @item -fimplicit-none
263 Specify that no implicit typing is allowed, unless overridden by explicit
264 @samp{IMPLICIT} statements. This is the equivalent of adding
265 @samp{implicit none} to the start of every procedure.
267 @cindex -fcray-pointer option
268 @cindex options, -fcray-pointer
270 Enables the Cray pointer extension, which provides a C-like pointer.
272 @cindex -std=@var{std} option
273 @cindex option, -std=@var{std}
275 Conform to the specified standard. Allowed values for @var{std} are
276 @samp{gnu}, @samp{f95}, @samp{f2003} and @samp{legacy}.
280 @node Warning Options
281 @section Options to Request or Suppress Warnings
282 @cindex options, warnings
283 @cindex warnings, suppressing
284 @cindex messages, warning
285 @cindex suppressing warnings
287 Warnings are diagnostic messages that report constructions which
288 are not inherently erroneous but which are risky or suggest there
289 might have been an error.
291 You can request many specific warnings with options beginning @option{-W},
292 for example @option{-Wimplicit} to request warnings on implicit
293 declarations. Each of these specific warning options also has a
294 negative form beginning @option{-Wno-} to turn off warnings;
295 for example, @option{-Wno-implicit}. This manual lists only one of the
296 two forms, whichever is not the default.
298 These options control the amount and kinds of warnings produced by GNU
302 @cindex syntax checking
303 @cindex -fsyntax-only option
304 @cindex options, -fsyntax-only
306 Check the code for syntax errors, but don't do anything beyond that.
308 @cindex -pedantic option
309 @cindex options, -pedantic
311 Issue warnings for uses of extensions to FORTRAN 95.
312 @option{-pedantic} also applies to C-language constructs where they
313 occur in GNU Fortran source files, such as use of @samp{\e} in a
314 character constant within a directive like @samp{#include}.
316 Valid FORTRAN 95 programs should compile properly with or without
318 However, without this option, certain GNU extensions and traditional
319 Fortran features are supported as well.
320 With this option, many of them are rejected.
322 Some users try to use @option{-pedantic} to check programs for conformance.
323 They soon find that it does not do quite what they want---it finds some
324 nonstandard practices, but not all.
325 However, improvements to @command{gfortran} in this area are welcome.
327 This should be used in conjunction with -std=@var{std}.
329 @cindex -pedantic-errors option
330 @cindex options, -pedantic-errors
331 @item -pedantic-errors
332 Like @option{-pedantic}, except that errors are produced rather than
338 Inhibit all warning messages.
342 @cindex options, -Wall
345 @cindex warnings, all
346 Enables commonly used warning options that which pertain to usage that
347 we recommend avoiding and that we believe is easy to avoid.
348 This currently includes @option{-Wunused-labels}, @option{-Waliasing},
349 @option{-Wsurprising}, @option{-Wnonstd-intrinsic} and
350 @option{-Wline-truncation}.
353 @cindex -Waliasing option
354 @cindex options, -Waliasing
357 Warn about possible aliasing of dummy arguments. Specifically, it warns
358 if the same actual argument is associated with a dummy argument with
359 @code{intent(in)} and a dummy argument with @code{intent(out)} in a call
360 with an explicit interface.
362 The following example will trigger the warning.
366 integer, intent(in) :: a
367 integer, intent(out) :: b
376 @cindex -Wconversion option
377 @cindex options, -Wconversion
380 Warn about implicit conversions between different types.
383 @cindex -Wimplicit-interface option
384 @cindex options, -Wimplicit-interface
385 @item -Wimplicit-interface
386 Warn about when procedure are called without an explicit interface.
387 Note this only checks that an explicit interface is present. It does not
388 check that the declared interfaces are consistent across program units.
391 @cindex -Wnonstd-intrinsic option
392 @cindex options, -Wnonstd-intrinsic
393 @item -Wnonstd-intrinsic
394 Warn if the user tries to use an intrinsic that does not belong to the
395 standard the user has chosen via the -std option.
399 @cindex options, -Wsurprising
402 Produce a warning when ``suspicious'' code constructs are encountered.
403 While technically legal these usually indicate that an error has been made.
405 This currently produces a warning under the following circumstances:
409 An INTEGER SELECT construct has a CASE that can never be matched as its
410 lower value is greater than its upper value.
413 A LOGICAL SELECT construct has three CASE statements.
417 @cindex options, -Wunderflow
420 Produce a warning when numerical constant expressions are
421 encountered, which yield an UNDERFLOW during compilation.
424 @cindex -Wunused-labels option
425 @cindex options, -Wunused-labels
426 @item -Wunused-labels
427 @cindex unused labels
428 @cindex labels, unused
429 Warn whenever a label is defined but never referenced.
433 @cindex options, -Werror
435 Turns all warnings into errors.
441 @cindex extra warnings
442 @cindex warnings, extra
443 Turns on ``extra warnings'' and, if optimization is specified
444 via @option{-O}, the @option{-Wuninitialized} option.
445 (This might change in future versions of @command{gfortran}
448 @xref{Warning Options,,Options to Request or Suppress Warnings,
449 gcc,Using the GNU Compiler Collection (GCC)}, for information on more
450 options offered by the GBE shared by @command{gfortran}, @command{gcc} and
453 Some of these have no effect when compiling programs written in Fortran.
455 @node Debugging Options
456 @section Options for Debugging Your Program or GNU Fortran
457 @cindex options, debugging
458 @cindex debugging information options
460 GNU Fortran has various special options that are used for debugging
461 either your program or @command{gfortran}
464 @cindex -fdump-parse-tree option
465 @cindex option, -fdump-parse-tree
466 @item -fdump-parse-tree
467 Output the internal parse tree before starting code generation. Only
468 really useful for debugging gfortran itself.
472 @cindex -ffpe-trap=@var{list} option
473 @cindex option, -ffpe-trap=@var{list}
474 @item -ffpe-trap=@var{list}
475 Specify a list of IEEE exceptions when a Floating Point Exception
476 (FPE) should be raised. On most systems, this will result in a SIGFPE
477 signal being sent and the program being interrupted, producing a core
478 file useful for debugging. @var{list} is a (possibly empty) comma-separated
479 list of the following IEEE exceptions: @samp{invalid} (invalid floating
480 point operation, such as @code{sqrt(-1.0)}), @samp{zero} (division by
481 zero), @samp{overflow} (overflow in a floating point operation),
482 @samp{underflow} (underflow in a floating point operation),
483 @samp{precision} (loss of precision during operation) and @samp{denormal}
484 (operation produced a denormal denormal value).
487 @xref{Debugging Options,,Options for Debugging Your Program or GCC,
488 gcc,Using the GNU Compiler Collection (GCC)}, for more information on
491 @node Directory Options
492 @section Options for Directory Search
493 @cindex directory, options
494 @cindex options, directory search
497 @cindex INCLUDE directive
498 @cindex directive, INCLUDE
499 These options affect how @command{gfortran} searches
500 for files specified by the @code{INCLUDE} directive and where it searches
501 for previously compiled modules.
503 It also affects the search paths used by @command{cpp} when used to preprocess
508 @cindex options, -Idir
510 @cindex directory, search paths for inclusion
511 @cindex inclusion, directory search paths for
512 @cindex search paths, for included files
513 @cindex paths, search
514 @cindex module search path
515 These affect interpretation of the @code{INCLUDE} directive
516 (as well as of the @code{#include} directive of the @command{cpp}
519 Also note that the general behavior of @option{-I} and
520 @code{INCLUDE} is pretty much the same as of @option{-I} with
521 @code{#include} in the @command{cpp} preprocessor, with regard to
522 looking for @file{header.gcc} files and other such things.
524 This path is also used to search for @samp{.mod} files when previously
525 compiled modules are required by a @code{USE} statement.
527 @xref{Directory Options,,Options for Directory Search,
528 gcc,Using the GNU Compiler Collection (GCC)}, for information on the
532 @cindex option, -Mdir
535 This option specifies where to put @samp{.mod} files for compiled modules.
536 It is also added to the list of directories to searched by an @code{USE}
539 The default is the current directory.
541 @option{-J} is an alias for @option{-M} to avoid conflicts with existing
545 @node Code Gen Options
546 @section Options for Code Generation Conventions
547 @cindex code generation, conventions
548 @cindex options, code generation
549 @cindex run-time, options
551 These machine-independent options control the interface conventions
552 used in code generation.
554 Most of them have both positive and negative forms; the negative form
555 of @option{-ffoo} would be @option{-fno-foo}. In the table below, only
556 one of the forms is listed---the one which is not the default. You
557 can figure out the other form by either removing @option{no-} or adding
561 @cindex @option{-fno-automatic} option
562 @cindex options, @option{-fno-automatic}
564 @cindex SAVE statement
565 @cindex statements, SAVE
566 Treat each program unit as if the @code{SAVE} statement was specified for
567 every local variable and array referenced in it. Does not affect common
568 blocks. (Some Fortran compilers provide this option under the name
571 @cindex @option{-ff2c} option
572 @cindex options, @option{-ff2c}
574 @cindex calling convention
575 @cindex @command{f2c} calling convention
576 @cindex @command{g77} calling convention
577 @cindex libf2c calling convention
578 Generate code designed to be compatible with code generated
579 by @command{g77} and @command{f2c}.
581 The calling conventions used by @command{g77} (originally implemented
582 in @command{f2c}) require functions that return type
583 default @code{REAL} to actually return the C type @code{double}, and
584 functions that return type @code{COMPLEX} to return the values via an
585 extra argument in the calling sequence that points to where to
586 store the return value. Under the default GNU calling conventions, such
587 functions simply return their results as they would in GNU
588 C -- default @code{REAL} functions return the C type @code{float}, and
589 @code{COMPLEX} functions return the GNU C type @code{complex}.
590 Additionally, this option implies the @option{-fsecond-underscore}
591 option, unless @option{-fno-second-underscore} is explicitly requested.
593 This does not affect the generation of code that interfaces with
594 the @command{libgfortran} library.
596 @emph{Caution:} It is not a good idea to mix Fortran code compiled
597 with @code{-ff2c} with code compiled with the default @code{-fno-f2c}
598 calling conventions as, calling @code{COMPLEX} or default @code{REAL}
599 functions between program parts which were compiled with different
600 calling conventions will break at execution time.
602 @emph{Caution:} This will break code which passes intrinsic functions
603 of type default @code{REAL} or @code{COMPLEX} as actual arguments, as
604 the library implementations use the @command{-fno-f2c} calling conventions.
606 @cindex @option{-fno-underscoring option}
607 @cindex options, @option{-fno-underscoring}
608 @item -fno-underscoring
610 @cindex symbol names, underscores
611 @cindex transforming symbol names
612 @cindex symbol names, transforming
613 Do not transform names of entities specified in the Fortran
614 source file by appending underscores to them.
616 With @option{-funderscoring} in effect, @command{gfortran} appends one
617 underscore to external names with no underscores. This is done to ensure
618 compatibility with code produced by many UNIX Fortran compilers.
620 @emph{Caution}: The default behavior of @command{gfortran} is
621 incompatible with @command{f2c} and @command{g77}, please use the
622 @option{-ff2c} option if you want object files compiled with
623 @option{gfortran} to be compatible with object code created with these
626 Use of @option{-fno-underscoring} is not recommended unless you are
627 experimenting with issues such as integration of (GNU) Fortran into
628 existing system environments (vis-a-vis existing libraries, tools, and
631 For example, with @option{-funderscoring}, and assuming other defaults like
632 @option{-fcase-lower} and that @samp{j()} and @samp{max_count()} are
633 external functions while @samp{my_var} and @samp{lvar} are local variables,
637 I = J() + MAX_COUNT (MY_VAR, LVAR)
641 is implemented as something akin to:
644 i = j_() + max_count__(&my_var__, &lvar);
647 With @option{-fno-underscoring}, the same statement is implemented as:
650 i = j() + max_count(&my_var, &lvar);
653 Use of @option{-fno-underscoring} allows direct specification of
654 user-defined names while debugging and when interfacing @command{gfortran}
655 code with other languages.
657 Note that just because the names match does @emph{not} mean that the
658 interface implemented by @command{gfortran} for an external name matches the
659 interface implemented by some other language for that same name.
660 That is, getting code produced by @command{gfortran} to link to code produced
661 by some other compiler using this or any other method can be only a
662 small part of the overall solution---getting the code generated by
663 both compilers to agree on issues other than naming can require
664 significant effort, and, unlike naming disagreements, linkers normally
665 cannot detect disagreements in these other areas.
667 Also, note that with @option{-fno-underscoring}, the lack of appended
668 underscores introduces the very real possibility that a user-defined
669 external name will conflict with a name in a system library, which
670 could make finding unresolved-reference bugs quite difficult in some
671 cases---they might occur at program run time, and show up only as
672 buggy behavior at run time.
674 In future versions of @command{gfortran} we hope to improve naming and linking
675 issues so that debugging always involves using the names as they appear
676 in the source, even if the names as seen by the linker are mangled to
677 prevent accidental linking between procedures with incompatible
680 @cindex @option{-fsecond-underscore option}
681 @cindex options, @option{-fsecond-underscore}
682 @item -fsecond-underscore
684 @cindex symbol names, underscores
685 @cindex transforming symbol names
686 @cindex symbol names, transforming
687 @cindex @command{f2c} calling convention
688 @cindex @command{g77} calling convention
689 @cindex libf2c calling convention
690 By default, @command{gfortran} appends an underscore to external
691 names. If this option is used @command{gfortran} appends two
692 underscores to names with underscores and one underscore to external names
693 with no underscores. (@command{gfortran} also appends two underscores to
694 internal names with underscores to avoid naming collisions with external
697 This option has no effect if @option{-fno-underscoring} is
698 in effect. It is implied by the @option{-ff2c} option.
700 Otherwise, with this option, an external name such as @samp{MAX_COUNT}
701 is implemented as a reference to the link-time external symbol
702 @samp{max_count__}, instead of @samp{max_count_}. This is required
703 for compatibility with @command{g77} and @command{f2c}, and is implied
704 by use of the @option{-ff2c} option.
707 @cindex -fbounds-check option
708 @cindex -ffortran-bounds-check option
710 @cindex bounds checking
711 @cindex range checking
712 @cindex array bounds checking
713 @cindex subscript checking
714 @cindex checking subscripts
715 Enable generation of run-time checks for array subscripts
716 and against the declared minimum and maximum values. It also
717 checks array indices for assumed and deferred
718 shape arrays against the actual allocated bounds.
720 In the future this may also include other forms of checking, eg. checking
721 substring references.
724 @cindex -fmax-stack-var-size option
725 @item -fmax-stack-var-size=@var{n}
726 This option specifies the size in bytes of the largest array that will be put
729 This option currently only affects local arrays declared with constant
730 bounds, and may not apply to all character variables.
731 Future versions of @command{gfortran} may improve this behavior.
733 The default value for @var{n} is 32768.
735 @cindex -fpackderived
737 @cindex Structure packing
738 This option tells gfortran to pack derived type members as closely as
739 possible. Code compiled with this option is likely to be incompatible
740 with code compiled without this option, and may execute slower.
742 @cindex -frepack-arrays option
743 @item -frepack-arrays
744 @cindex Repacking arrays
745 In some circumstances @command{gfortran} may pass assumed shape array
746 sections via a descriptor describing a discontiguous area of memory.
747 This option adds code to the function prologue to repack the data into
748 a contiguous block at runtime.
750 This should result in faster accesses to the array. However it can introduce
751 significant overhead to the function call, especially when the passed data
754 @cindex -fshort-enums
756 This option is provided for interoperability with C code that was
757 compiled with the @command{-fshort-enums} option. It will make
758 @command{gfortran} choose the smallest @code{INTEGER} kind a given
759 enumerator set will fit in, and give all its enumerators this kind.
762 @xref{Code Gen Options,,Options for Code Generation Conventions,
763 gcc,Using the GNU Compiler Collection (GCC)}, for information on more options
765 shared by @command{gfortran} @command{gcc} and other GNU compilers.
770 @node Environment Variables
771 @section Environment Variables Affecting GNU Fortran
772 @cindex environment variables
774 @c man begin ENVIRONMENT
776 GNU Fortran 95 currently does not make use of any environment
777 variables to control its operation above and beyond those
778 that affect the operation of @command{gcc}.
780 @xref{Environment Variables,,Environment Variables Affecting GCC,
781 gcc,Using the GNU Compiler Collection (GCC)}, for information on environment