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
229 Compile switch to change the interpretation of a backslash from
230 ``C''-style escape characters to a single backslash character.
232 @cindex -ffixed-line-length-@var{n} option
233 @cindex options, -ffixed-line-length-@var{n}
234 @item -ffixed-line-length-@var{n}
235 @cindex source file format
236 @cindex lines, length
237 @cindex length of source lines
239 @cindex limits, lengths of source lines
240 Set column after which characters are ignored in typical fixed-form
241 lines in the source file, and through which spaces are assumed (as
242 if padded to that length) after the ends of short fixed-form lines.
245 @cindex extended-source option
246 Popular values for @var{n} include 72 (the
247 standard and the default), 80 (card image), and 132 (corresponds
248 to ``extended-source'' options in some popular compilers).
249 @var{n} may be @samp{none}, meaning that the entire line is meaningful
250 and that continued character constants never have implicit spaces appended
251 to them to fill out the line.
252 @option{-ffixed-line-length-0} means the same thing as
253 @option{-ffixed-line-length-none}.
255 @cindex -fmax-identifier-length=@var{n} option
256 @cindex option -fmax-identifier-length=@var{n}
257 @item -fmax-identifier-length=@var{n}
258 Specify the maximum allowed identifier length. Typical values are
259 31 (Fortran 95) and 63 (Fortran 200x).
261 @cindex -fimplicit-none option
262 @cindex options, -fimplicit-none
263 @item -fimplicit-none
264 Specify that no implicit typing is allowed, unless overridden by explicit
265 @samp{IMPLICIT} statements. This is the equivalent of adding
266 @samp{implicit none} to the start of every procedure.
268 @cindex -fcray-pointer option
269 @cindex options, -fcray-pointer
271 Enables the Cray pointer extension, which provides a C-like pointer.
273 @cindex -std=@var{std} option
274 @cindex option, -std=@var{std}
276 Conform to the specified standard. Allowed values for @var{std} are
277 @samp{gnu}, @samp{f95}, @samp{f2003} and @samp{legacy}.
281 @node Warning Options
282 @section Options to Request or Suppress Warnings
283 @cindex options, warnings
284 @cindex warnings, suppressing
285 @cindex messages, warning
286 @cindex suppressing warnings
288 Warnings are diagnostic messages that report constructions which
289 are not inherently erroneous but which are risky or suggest there
290 might have been an error.
292 You can request many specific warnings with options beginning @option{-W},
293 for example @option{-Wimplicit} to request warnings on implicit
294 declarations. Each of these specific warning options also has a
295 negative form beginning @option{-Wno-} to turn off warnings;
296 for example, @option{-Wno-implicit}. This manual lists only one of the
297 two forms, whichever is not the default.
299 These options control the amount and kinds of warnings produced by GNU
303 @cindex syntax checking
304 @cindex -fsyntax-only option
305 @cindex options, -fsyntax-only
307 Check the code for syntax errors, but don't do anything beyond that.
309 @cindex -pedantic option
310 @cindex options, -pedantic
312 Issue warnings for uses of extensions to FORTRAN 95.
313 @option{-pedantic} also applies to C-language constructs where they
314 occur in GNU Fortran source files, such as use of @samp{\e} in a
315 character constant within a directive like @samp{#include}.
317 Valid FORTRAN 95 programs should compile properly with or without
319 However, without this option, certain GNU extensions and traditional
320 Fortran features are supported as well.
321 With this option, many of them are rejected.
323 Some users try to use @option{-pedantic} to check programs for conformance.
324 They soon find that it does not do quite what they want---it finds some
325 nonstandard practices, but not all.
326 However, improvements to @command{gfortran} in this area are welcome.
328 This should be used in conjunction with -std=@var{std}.
330 @cindex -pedantic-errors option
331 @cindex options, -pedantic-errors
332 @item -pedantic-errors
333 Like @option{-pedantic}, except that errors are produced rather than
339 Inhibit all warning messages.
343 @cindex options, -Wall
346 @cindex warnings, all
347 Enables commonly used warning options that which pertain to usage that
348 we recommend avoiding and that we believe is easy to avoid.
349 This currently includes @option{-Wunused-labels}, @option{-Waliasing},
350 @option{-Wsurprising}, @option{-Wnonstd-intrinsic} and
351 @option{-Wline-truncation}.
354 @cindex -Waliasing option
355 @cindex options, -Waliasing
358 Warn about possible aliasing of dummy arguments. Specifically, it warns
359 if the same actual argument is associated with a dummy argument with
360 @code{intent(in)} and a dummy argument with @code{intent(out)} in a call
361 with an explicit interface.
363 The following example will trigger the warning.
367 integer, intent(in) :: a
368 integer, intent(out) :: b
377 @cindex -Wconversion option
378 @cindex options, -Wconversion
381 Warn about implicit conversions between different types.
384 @cindex -Wimplicit-interface option
385 @cindex options, -Wimplicit-interface
386 @item -Wimplicit-interface
387 Warn about when procedure are called without an explicit interface.
388 Note this only checks that an explicit interface is present. It does not
389 check that the declared interfaces are consistent across program units.
392 @cindex -Wnonstd-intrinsic option
393 @cindex options, -Wnonstd-intrinsic
394 @item -Wnonstd-intrinsic
395 Warn if the user tries to use an intrinsic that does not belong to the
396 standard the user has chosen via the -std option.
400 @cindex options, -Wsurprising
403 Produce a warning when ``suspicious'' code constructs are encountered.
404 While technically legal these usually indicate that an error has been made.
406 This currently produces a warning under the following circumstances:
410 An INTEGER SELECT construct has a CASE that can never be matched as its
411 lower value is greater than its upper value.
414 A LOGICAL SELECT construct has three CASE statements.
418 @cindex options, -Wunderflow
421 Produce a warning when numerical constant expressions are
422 encountered, which yield an UNDERFLOW during compilation.
425 @cindex -Wunused-labels option
426 @cindex options, -Wunused-labels
427 @item -Wunused-labels
428 @cindex unused labels
429 @cindex labels, unused
430 Warn whenever a label is defined but never referenced.
434 @cindex options, -Werror
436 Turns all warnings into errors.
442 @cindex extra warnings
443 @cindex warnings, extra
444 Turns on ``extra warnings'' and, if optimization is specified
445 via @option{-O}, the @option{-Wuninitialized} option.
446 (This might change in future versions of @command{gfortran}
449 @xref{Warning Options,,Options to Request or Suppress Warnings,
450 gcc,Using the GNU Compiler Collection (GCC)}, for information on more
451 options offered by the GBE shared by @command{gfortran}, @command{gcc} and
454 Some of these have no effect when compiling programs written in Fortran.
456 @node Debugging Options
457 @section Options for Debugging Your Program or GNU Fortran
458 @cindex options, debugging
459 @cindex debugging information options
461 GNU Fortran has various special options that are used for debugging
462 either your program or @command{gfortran}
465 @cindex -fdump-parse-tree option
466 @cindex option, -fdump-parse-tree
467 @item -fdump-parse-tree
468 Output the internal parse tree before starting code generation. Only
469 really useful for debugging gfortran itself.
473 @cindex -ffpe-trap=@var{list} option
474 @cindex option, -ffpe-trap=@var{list}
475 @item -ffpe-trap=@var{list}
476 Specify a list of IEEE exceptions when a Floating Point Exception
477 (FPE) should be raised. On most systems, this will result in a SIGFPE
478 signal being sent and the program being interrupted, producing a core
479 file useful for debugging. @var{list} is a (possibly empty) comma-separated
480 list of the following IEEE exceptions: @samp{invalid} (invalid floating
481 point operation, such as @code{sqrt(-1.0)}), @samp{zero} (division by
482 zero), @samp{overflow} (overflow in a floating point operation),
483 @samp{underflow} (underflow in a floating point operation),
484 @samp{precision} (loss of precision during operation) and @samp{denormal}
485 (operation produced a denormal denormal value).
488 @xref{Debugging Options,,Options for Debugging Your Program or GCC,
489 gcc,Using the GNU Compiler Collection (GCC)}, for more information on
492 @node Directory Options
493 @section Options for Directory Search
494 @cindex directory, options
495 @cindex options, directory search
498 @cindex INCLUDE directive
499 @cindex directive, INCLUDE
500 These options affect how @command{gfortran} searches
501 for files specified by the @code{INCLUDE} directive and where it searches
502 for previously compiled modules.
504 It also affects the search paths used by @command{cpp} when used to preprocess
509 @cindex options, -Idir
511 @cindex directory, search paths for inclusion
512 @cindex inclusion, directory search paths for
513 @cindex search paths, for included files
514 @cindex paths, search
515 @cindex module search path
516 These affect interpretation of the @code{INCLUDE} directive
517 (as well as of the @code{#include} directive of the @command{cpp}
520 Also note that the general behavior of @option{-I} and
521 @code{INCLUDE} is pretty much the same as of @option{-I} with
522 @code{#include} in the @command{cpp} preprocessor, with regard to
523 looking for @file{header.gcc} files and other such things.
525 This path is also used to search for @samp{.mod} files when previously
526 compiled modules are required by a @code{USE} statement.
528 @xref{Directory Options,,Options for Directory Search,
529 gcc,Using the GNU Compiler Collection (GCC)}, for information on the
533 @cindex option, -Mdir
536 This option specifies where to put @samp{.mod} files for compiled modules.
537 It is also added to the list of directories to searched by an @code{USE}
540 The default is the current directory.
542 @option{-J} is an alias for @option{-M} to avoid conflicts with existing
546 @node Code Gen Options
547 @section Options for Code Generation Conventions
548 @cindex code generation, conventions
549 @cindex options, code generation
550 @cindex run-time, options
552 These machine-independent options control the interface conventions
553 used in code generation.
555 Most of them have both positive and negative forms; the negative form
556 of @option{-ffoo} would be @option{-fno-foo}. In the table below, only
557 one of the forms is listed---the one which is not the default. You
558 can figure out the other form by either removing @option{no-} or adding
562 @cindex @option{-fno-automatic} option
563 @cindex options, @option{-fno-automatic}
565 @cindex SAVE statement
566 @cindex statements, SAVE
567 Treat each program unit as if the @code{SAVE} statement was specified for
568 every local variable and array referenced in it. Does not affect common
569 blocks. (Some Fortran compilers provide this option under the name
572 @cindex @option{-ff2c} option
573 @cindex options, @option{-ff2c}
575 @cindex calling convention
576 @cindex @command{f2c} calling convention
577 @cindex @command{g77} calling convention
578 @cindex libf2c calling convention
579 Generate code designed to be compatible with code generated
580 by @command{g77} and @command{f2c}.
582 The calling conventions used by @command{g77} (originally implemented
583 in @command{f2c}) require functions that return type
584 default @code{REAL} to actually return the C type @code{double}, and
585 functions that return type @code{COMPLEX} to return the values via an
586 extra argument in the calling sequence that points to where to
587 store the return value. Under the default GNU calling conventions, such
588 functions simply return their results as they would in GNU
589 C -- default @code{REAL} functions return the C type @code{float}, and
590 @code{COMPLEX} functions return the GNU C type @code{complex}.
591 Additionally, this option implies the @option{-fsecond-underscore}
592 option, unless @option{-fno-second-underscore} is explicitly requested.
594 This does not affect the generation of code that interfaces with
595 the @command{libgfortran} library.
597 @emph{Caution:} It is not a good idea to mix Fortran code compiled
598 with @code{-ff2c} with code compiled with the default @code{-fno-f2c}
599 calling conventions as, calling @code{COMPLEX} or default @code{REAL}
600 functions between program parts which were compiled with different
601 calling conventions will break at execution time.
603 @emph{Caution:} This will break code which passes intrinsic functions
604 of type default @code{REAL} or @code{COMPLEX} as actual arguments, as
605 the library implementations use the @command{-fno-f2c} calling conventions.
607 @cindex @option{-fno-underscoring option}
608 @cindex options, @option{-fno-underscoring}
609 @item -fno-underscoring
611 @cindex symbol names, underscores
612 @cindex transforming symbol names
613 @cindex symbol names, transforming
614 Do not transform names of entities specified in the Fortran
615 source file by appending underscores to them.
617 With @option{-funderscoring} in effect, @command{gfortran} appends one
618 underscore to external names with no underscores. This is done to ensure
619 compatibility with code produced by many UNIX Fortran compilers.
621 @emph{Caution}: The default behavior of @command{gfortran} is
622 incompatible with @command{f2c} and @command{g77}, please use the
623 @option{-ff2c} option if you want object files compiled with
624 @option{gfortran} to be compatible with object code created with these
627 Use of @option{-fno-underscoring} is not recommended unless you are
628 experimenting with issues such as integration of (GNU) Fortran into
629 existing system environments (vis-a-vis existing libraries, tools, and
632 For example, with @option{-funderscoring}, and assuming other defaults like
633 @option{-fcase-lower} and that @samp{j()} and @samp{max_count()} are
634 external functions while @samp{my_var} and @samp{lvar} are local variables,
638 I = J() + MAX_COUNT (MY_VAR, LVAR)
642 is implemented as something akin to:
645 i = j_() + max_count__(&my_var__, &lvar);
648 With @option{-fno-underscoring}, the same statement is implemented as:
651 i = j() + max_count(&my_var, &lvar);
654 Use of @option{-fno-underscoring} allows direct specification of
655 user-defined names while debugging and when interfacing @command{gfortran}
656 code with other languages.
658 Note that just because the names match does @emph{not} mean that the
659 interface implemented by @command{gfortran} for an external name matches the
660 interface implemented by some other language for that same name.
661 That is, getting code produced by @command{gfortran} to link to code produced
662 by some other compiler using this or any other method can be only a
663 small part of the overall solution---getting the code generated by
664 both compilers to agree on issues other than naming can require
665 significant effort, and, unlike naming disagreements, linkers normally
666 cannot detect disagreements in these other areas.
668 Also, note that with @option{-fno-underscoring}, the lack of appended
669 underscores introduces the very real possibility that a user-defined
670 external name will conflict with a name in a system library, which
671 could make finding unresolved-reference bugs quite difficult in some
672 cases---they might occur at program run time, and show up only as
673 buggy behavior at run time.
675 In future versions of @command{gfortran} we hope to improve naming and linking
676 issues so that debugging always involves using the names as they appear
677 in the source, even if the names as seen by the linker are mangled to
678 prevent accidental linking between procedures with incompatible
681 @cindex @option{-fsecond-underscore option}
682 @cindex options, @option{-fsecond-underscore}
683 @item -fsecond-underscore
685 @cindex symbol names, underscores
686 @cindex transforming symbol names
687 @cindex symbol names, transforming
688 @cindex @command{f2c} calling convention
689 @cindex @command{g77} calling convention
690 @cindex libf2c calling convention
691 By default, @command{gfortran} appends an underscore to external
692 names. If this option is used @command{gfortran} appends two
693 underscores to names with underscores and one underscore to external names
694 with no underscores. (@command{gfortran} also appends two underscores to
695 internal names with underscores to avoid naming collisions with external
698 This option has no effect if @option{-fno-underscoring} is
699 in effect. It is implied by the @option{-ff2c} option.
701 Otherwise, with this option, an external name such as @samp{MAX_COUNT}
702 is implemented as a reference to the link-time external symbol
703 @samp{max_count__}, instead of @samp{max_count_}. This is required
704 for compatibility with @command{g77} and @command{f2c}, and is implied
705 by use of the @option{-ff2c} option.
708 @cindex -fbounds-check option
709 @cindex -ffortran-bounds-check option
711 @cindex bounds checking
712 @cindex range checking
713 @cindex array bounds checking
714 @cindex subscript checking
715 @cindex checking subscripts
716 Enable generation of run-time checks for array subscripts
717 and against the declared minimum and maximum values. It also
718 checks array indices for assumed and deferred
719 shape arrays against the actual allocated bounds.
721 In the future this may also include other forms of checking, eg. checking
722 substring references.
725 @cindex -fmax-stack-var-size option
726 @item -fmax-stack-var-size=@var{n}
727 This option specifies the size in bytes of the largest array that will be put
730 This option currently only affects local arrays declared with constant
731 bounds, and may not apply to all character variables.
732 Future versions of @command{gfortran} may improve this behavior.
734 The default value for @var{n} is 32768.
736 @cindex -fpackderived
738 @cindex Structure packing
739 This option tells gfortran to pack derived type members as closely as
740 possible. Code compiled with this option is likely to be incompatible
741 with code compiled without this option, and may execute slower.
743 @cindex -frepack-arrays option
744 @item -frepack-arrays
745 @cindex Repacking arrays
746 In some circumstances @command{gfortran} may pass assumed shape array
747 sections via a descriptor describing a discontiguous area of memory.
748 This option adds code to the function prologue to repack the data into
749 a contiguous block at runtime.
751 This should result in faster accesses to the array. However it can introduce
752 significant overhead to the function call, especially when the passed data
755 @cindex -fshort-enums
757 This option is provided for interoperability with C code that was
758 compiled with the @command{-fshort-enums} option. It will make
759 @command{gfortran} choose the smallest @code{INTEGER} kind a given
760 enumerator set will fit in, and give all its enumerators this kind.
763 @xref{Code Gen Options,,Options for Code Generation Conventions,
764 gcc,Using the GNU Compiler Collection (GCC)}, for information on more options
766 shared by @command{gfortran} @command{gcc} and other GNU compilers.
771 @node Environment Variables
772 @section Environment Variables Affecting GNU Fortran
773 @cindex environment variables
775 @c man begin ENVIRONMENT
777 GNU Fortran 95 currently does not make use of any environment
778 variables to control its operation above and beyond those
779 that affect the operation of @command{gcc}.
781 @xref{Environment Variables,,Environment Variables Affecting GCC,
782 gcc,Using the GNU Compiler Collection (GCC)}, for information on environment