@setfilename standards.info
@settitle GNU Coding Standards
@c This date is automagically updated when you save this file:
-@set lastupdate March 13, 1998
+@set lastupdate June 8, 2010
@c %**end of header
-@ifinfo
-@format
-START-INFO-DIR-ENTRY
-* Standards: (standards). GNU coding standards.
-END-INFO-DIR-ENTRY
-@end format
-@end ifinfo
+@dircategory GNU organization
+@direntry
+* Standards: (standards). GNU coding standards.
+@end direntry
@c @setchapternewpage odd
@setchapternewpage off
+@c Put everything in one index (arbitrarily chosen to be the concept index).
+@syncodeindex fn cp
+@syncodeindex ky cp
+@syncodeindex pg cp
+@syncodeindex vr cp
+
@c This is used by a cross ref in make-stds.texi
@set CODESTD 1
@iftex
@set CHAPTER node
@end ifinfo
-@ifinfo
-GNU Coding Standards
-Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 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.
-
-@ignore
-Permission is granted to process this file through TeX and print the
-results, provided the printed document carries copying permission
-notice identical to this one except for the removal of this paragraph
-(this paragraph not being relevant to the printed manual).
-@end ignore
-
-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 stated in a translation approved
-by the Free Software Foundation.
-@end ifinfo
+@copying
+The GNU coding standards, last updated @value{lastupdate}.
+
+Copyright @copyright{} 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
+2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2010 Free Software
+Foundation, Inc.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3
+or any later version published by the Free Software Foundation;
+with no Invariant Sections, with no
+Front-Cover Texts, and with no Back-Cover Texts.
+A copy of the license is included in the section entitled ``GNU
+Free Documentation License''.
+@end copying
@titlepage
@title GNU Coding Standards
-@author Richard Stallman
+@author Richard Stallman, et al.
@author last updated @value{lastupdate}
@page
-
@vskip 0pt plus 1filll
-Copyright @copyright{} 1992, 1993, 1994, 1995, 1996, 1997, 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 stated in a translation approved
-by the Free Software Foundation.
+@insertcopying
@end titlepage
-@ifinfo
+@contents
+
+@ifnottex
@node Top, Preface, (dir), (dir)
@top Version
-Last updated @value{lastupdate}.
-@end ifinfo
+@insertcopying
+@end ifnottex
@menu
-* Preface:: About the GNU Coding Standards
-* Intellectual Property:: Keeping Free Software Free
-* Design Advice:: General Program Design
-* Program Behavior:: Program Behavior for All Programs
-* Writing C:: Making The Best Use of C
-* Documentation:: Documenting Programs
-* Managing Releases:: The Release Process
+* Preface:: About the GNU Coding Standards.
+* Legal Issues:: Keeping free software free.
+* Design Advice:: General program design.
+* Program Behavior:: Program behavior for all programs
+* Writing C:: Making the best use of C.
+* Documentation:: Documenting programs.
+* Managing Releases:: The release process.
+* References:: Mentioning non-free software or documentation.
+* GNU Free Documentation License:: Copying and sharing this manual.
+* Index::
+
@end menu
@node Preface
even if you write in another programming language. The rules often
state reasons for writing in a certain way.
+This release of the GNU Coding Standards was last updated
+@value{lastupdate}.
+
+@cindex where to obtain @code{standards.texi}
+@cindex downloading this manual
+If you did not obtain this file directly from the GNU project and
+recently, please check for a newer version. You can get the GNU
+Coding Standards from the GNU web server in many
+different formats, including the Texinfo source, PDF, HTML, DVI, plain
+text, and more, at: @uref{http://www.gnu.org/prep/standards/}.
+
Corrections or suggestions for this document should be sent to
-@email{gnu@@gnu.org}. If you make a suggestion, please include a
+@email{bug-standards@@gnu.org}. If you make a suggestion, please include a
suggested new wording for it; our time is limited. We prefer a context
diff to the @file{standards.texi} or @file{make-stds.texi} files, but if
you don't have those files, please mail your suggestion anyway.
-This release of the GNU Coding Standards was last updated
-@value{lastupdate}.
+These standards cover the minimum of what is important when writing a
+GNU package. Likely, the need for additional standards will come up.
+Sometimes, you might suggest that such standards be added to this
+document. If you think your standards would be generally useful, please
+do suggest them.
-@node Intellectual Property
+You should also set standards for your package on many questions not
+addressed or not firmly specified here. The most important point is to
+be self-consistent---try to stick to the conventions you pick, and try
+to document them as much as possible. That way, your program will be
+more maintainable by others.
+
+The GNU Hello program serves as an example of how to follow the GNU
+coding standards for a trivial program.
+@uref{http://www.gnu.org/software/hello/hello.html}.
+
+@node Legal Issues
@chapter Keeping Free Software Free
+@cindex legal aspects
-This @value{CHAPTER} discusses how you can make sure that GNU software
-remains unencumbered.
+This chapter discusses how you can make sure that GNU software
+avoids legal difficulties, and other related issues.
@menu
-* Reading Non-Free Code:: Referring to Proprietary Programs
-* Contributions:: Accepting Contributions
+* Reading Non-Free Code:: Referring to proprietary programs.
+* Contributions:: Accepting contributions.
+* Trademarks:: How we deal with trademark issues.
@end menu
@node Reading Non-Free Code
@section Referring to Proprietary Programs
+@cindex proprietary programs
+@cindex avoiding proprietary code
Don't in any circumstances refer to Unix source code for or during
your work on GNU! (Or to any other proprietary programs.)
For example, Unix utilities were generally optimized to minimize
memory use; if you go for speed instead, your program will be very
-different. You could keep the entire input file in core and scan it
+different. You could keep the entire input file in memory and scan it
there instead of using stdio. Use a smarter algorithm discovered more
recently than the Unix program. Eliminate use of temporary files. Do
it in one pass instead of two (we did this in the assembler).
Or use a simple garbage collector instead of tracking precisely when
to free memory, or use a new GNU facility such as obstacks.
-
@node Contributions
@section Accepting Contributions
-
-If someone else sends you a piece of code to add to the program you are
-working on, we need legal papers to use it---the same sort of legal
-papers we will need to get from you. @emph{Each} significant
-contributor to a program must sign some sort of legal papers in order
-for us to have clear title to the program. The main author alone is not
+@cindex legal papers
+@cindex accepting contributions
+
+If the program you are working on is copyrighted by the Free Software
+Foundation, then when someone else sends you a piece of code to add to
+the program, we need legal papers to use it---just as we asked you to
+sign papers initially. @emph{Each} person who makes a nontrivial
+contribution to a program must sign some sort of legal papers in order
+for us to have clear title to the program; the main author alone is not
enough.
So, before adding in any contributions from other people, please tell
law, comments and code are just text. Copyright applies to all kinds of
text, so we need legal papers for all kinds.
+We know it is frustrating to ask for legal papers; it's frustrating for
+us as well. But if you don't wait, you are going out on a limb---for
+example, what if the contributor's employer won't sign a disclaimer?
+You might have to take that code out again!
+
You don't need papers for changes of a few lines here or there, since
they are not significant for copyright purposes. Also, you don't need
papers if all you get from the suggestion is some ideas, not actual code
-which you use. For example, if you write a different solution to the
-problem, you don't need to get papers.
-
-We know this is frustrating; it's frustrating for us as well. But if
-you don't wait, you are going out on a limb---for example, what if the
-contributor's employer won't sign a disclaimer? You might have to take
-that code out again!
+which you use. For example, if someone sent you one implementation, but
+you write a different implementation of the same idea, you don't need to
+get papers.
The very worst thing is if you forget to tell us about the other
contributor. We could be very embarrassed in court some day as a
We have more detailed advice for maintainers of programs; if you have
reached the stage of actually maintaining a program for GNU (whether
-released or not), please ask us for a copy.
+released or not), please ask us for a copy. It is also available
+online for your perusal: @uref{http://www.gnu.org/prep/maintain/}.
+
+@node Trademarks
+@section Trademarks
+@cindex trademarks
+
+Please do not include any trademark acknowledgements in GNU software
+packages or documentation.
+
+Trademark acknowledgements are the statements that such-and-such is a
+trademark of so-and-so. The GNU Project has no objection to the basic
+idea of trademarks, but these acknowledgements feel like kowtowing,
+and there is no legal requirement for them, so we don't use them.
+
+What is legally required, as regards other people's trademarks, is to
+avoid using them in ways which a reader might reasonably understand as
+naming or labeling our own programs or activities. For example, since
+``Objective C'' is (or at least was) a trademark, we made sure to say
+that we provide a ``compiler for the Objective C language'' rather
+than an ``Objective C compiler''. The latter would have been meant as
+a shorter way of saying the former, but it does not explicitly state
+the relationship, so it could be misinterpreted as using ``Objective
+C'' as a label for the compiler rather than for the language.
+
+Please don't use ``win'' as an abbreviation for Microsoft Windows in
+GNU software or documentation. In hacker terminology, calling
+something a ``win'' is a form of praise. If you wish to praise
+Microsoft Windows when speaking on your own, by all means do so, but
+not in GNU software. Usually we write the name ``Windows'' in full,
+but when brevity is very important (as in file names and sometimes
+symbol names), we abbreviate it to ``w''. For instance, the files and
+functions in Emacs that deal with Windows start with @samp{w32}.
@node Design Advice
@chapter General Program Design
+@cindex program design
-This @value{CHAPTER} discusses some of the issues you should take into
+This chapter discusses some of the issues you should take into
account when designing your program.
+@c Standard or ANSI C
+@c
+@c In 1989 the American National Standards Institute (ANSI) standardized
+@c C as standard X3.159-1989. In December of that year the
+@c International Standards Organization ISO adopted the ANSI C standard
+@c making minor changes. In 1990 ANSI then re-adopted ISO standard
+@c C. This version of C is known as either ANSI C or Standard C.
+
+@c A major revision of the C Standard appeared in 1999.
+
@menu
-* Compatibility:: Compatibility with other implementations
-* Using Extensions:: Using non-standard features
-* ANSI C:: Using ANSI C features
-* Source Language:: Using languages other than C
+* Source Language:: Which languages to use.
+* Compatibility:: Compatibility with other implementations.
+* Using Extensions:: Using non-standard features.
+* Standard C:: Using standard C features.
+* Conditional Compilation:: Compiling code only if a conditional is true.
@end menu
+@node Source Language
+@section Which Languages to Use
+@cindex programming languages
+
+When you want to use a language that gets compiled and runs at high
+speed, the best language to use is C. Using another language is like
+using a non-standard feature: it will cause trouble for users. Even if
+GCC supports the other language, users may find it inconvenient to have
+to install the compiler for that other language in order to build your
+program. For example, if you write your program in C++, people will
+have to install the GNU C++ compiler in order to compile your program.
+
+C has one other advantage over C++ and other compiled languages: more
+people know C, so more people will find it easy to read and modify the
+program if it is written in C.
+
+So in general it is much better to use C, rather than the
+comparable alternatives.
+
+But there are two exceptions to that conclusion:
+
+@itemize @bullet
+@item
+It is no problem to use another language to write a tool specifically
+intended for use with that language. That is because the only people
+who want to build the tool will be those who have installed the other
+language anyway.
+
+@item
+If an application is of interest only to a narrow part of the community,
+then the question of which language it is written in has less effect on
+other people, so you may as well please yourself.
+@end itemize
+
+Many programs are designed to be extensible: they include an interpreter
+for a language that is higher level than C. Often much of the program
+is written in that language, too. The Emacs editor pioneered this
+technique.
+
+@cindex GUILE
+The standard extensibility interpreter for GNU software is GUILE
+(@uref{http://www.gnu.org/software/guile/}), which implements the
+language Scheme (an especially clean and simple dialect of Lisp). We
+don't reject programs written in other ``scripting languages'' such as
+Perl and Python, but using GUILE is very important for the overall
+consistency of the GNU system.
+
@node Compatibility
@section Compatibility with Other Implementations
+@cindex compatibility with C and @sc{posix} standards
+@cindex @sc{posix} compatibility
With occasional exceptions, utility programs and libraries for GNU
should be upward compatible with those in Berkeley Unix, and upward
-compatible with @sc{ansi} C if @sc{ansi} C specifies their behavior, and
-upward compatible with @sc{POSIX} if @sc{POSIX} specifies their
-behavior.
+compatible with Standard C if Standard C specifies their
+behavior, and upward compatible with @sc{posix} if @sc{posix} specifies
+their behavior.
When these standards conflict, it is useful to offer compatibility
modes for each of them.
-@sc{ansi} C and @sc{POSIX} prohibit many kinds of extensions. Feel free
-to make the extensions anyway, and include a @samp{--ansi},
+@cindex options for compatibility
+Standard C and @sc{posix} prohibit many kinds of extensions. Feel
+free to make the extensions anyway, and include a @samp{--ansi},
@samp{--posix}, or @samp{--compatible} option to turn them off.
However, if the extension has a significant chance of breaking any real
-programs or scripts, then it is not really upward compatible. Try to
-redesign its interface.
+programs or scripts, then it is not really upward compatible. So you
+should try to redesign its interface to make it upward compatible.
-Many GNU programs suppress extensions that conflict with POSIX if the
+@cindex @code{POSIXLY_CORRECT}, environment variable
+Many GNU programs suppress extensions that conflict with @sc{posix} if the
environment variable @code{POSIXLY_CORRECT} is defined (even if it is
defined with a null value). Please make your program recognize this
variable if appropriate.
@code{vi} is replaced with Emacs.) But it is nice to offer a compatible
feature as well. (There is a free @code{vi} clone, so we offer it.)
-Additional useful features not in Berkeley Unix are welcome.
+Additional useful features are welcome regardless of whether
+there is any precedent for them.
@node Using Extensions
@section Using Non-standard Features
+@cindex non-standard extensions
Many GNU facilities that already exist support a number of convenient
extensions over the comparable Unix facilities. Whether to use these
are a big improvement.
An exception to this rule are the large, established programs (such as
-Emacs) which run on a great variety of systems. Such programs would
-be broken by use of GNU extensions.
+Emacs) which run on a great variety of systems. Using GNU extensions in
+such programs would make many users unhappy, so we don't do that.
+
+Another exception is for programs that are used as part of compilation:
+anything that must be compiled with other compilers in order to
+bootstrap the GNU compilation facilities. If these require the GNU
+compiler, then no one can compile them without having them installed
+already. That would be extremely troublesome in certain cases.
-Another exception is for programs that are used as part of
-compilation: anything that must be compiled with other compilers in
-order to bootstrap the GNU compilation facilities. If these require
-the GNU compiler, then no one can compile them without having them
-installed already. That would be no good.
+@node Standard C
+@section Standard C and Pre-Standard C
+@cindex @sc{ansi} C standard
-@node ANSI C
-@section @sc{ansi} C and pre-@sc{ansi} C
+1989 Standard C is widespread enough now that it is ok to use its
+features in new programs. There is one exception: do not ever use the
+``trigraph'' feature of Standard C.
-Do not ever use the ``trigraph'' feature of @sc{ansi} C.
+1999 Standard C is not widespread yet, so please do not require its
+features in programs. It is ok to use its features if they are present.
-@sc{ansi} C is widespread enough now that it is ok to write new programs
-that use @sc{ansi} C features (and therefore will not work in
-non-@sc{ansi} compilers). And if a program is already written in
-@sc{ansi} C, there's no need to convert it to support non-@sc{ansi}
-compilers.
+However, it is easy to support pre-standard compilers in most programs,
+so if you know how to do that, feel free. If a program you are
+maintaining has such support, you should try to keep it working.
-However, it is easy to support non-@sc{ansi} compilers in most programs,
-so you might still consider doing so when you write a program. Instead
-of writing function definitions in @sc{ansi} prototype form,
+@cindex function prototypes
+To support pre-standard C, instead of writing function definitions in
+standard prototype form,
@example
int
@end example
@noindent
-write the definition in pre-@sc{ansi} style like this,
+write the definition in pre-standard style like this,
@example
int
@end example
You need such a declaration anyway, in a header file, to get the benefit
-of @sc{ansi} C prototypes in all the files where the function is called.
-And once you have it, you lose nothing by writing the function
-definition in the pre-@sc{ansi} style.
+of prototypes in all the files where the function is called. And once
+you have the declaration, you normally lose nothing by writing the
+function definition in the pre-standard style.
+
+This technique does not work for integer types narrower than @code{int}.
+If you think of an argument as being of a type narrower than @code{int},
+declare it as @code{int} instead.
+
+There are a few special cases where this technique is hard to use. For
+example, if a function argument needs to hold the system type
+@code{dev_t}, you run into trouble, because @code{dev_t} is shorter than
+@code{int} on some machines; but you cannot use @code{int} instead,
+because @code{dev_t} is wider than @code{int} on some machines. There
+is no type you can safely use on all machines in a non-standard
+definition. The only way to support non-standard C and pass such an
+argument is to check the width of @code{dev_t} using Autoconf and choose
+the argument type accordingly. This may not be worth the trouble.
+
+In order to support pre-standard compilers that do not recognize
+prototypes, you may want to use a preprocessor macro like this:
-If you don't know non-@sc{ansi} C, there's no need to learn it; just
-write in @sc{ansi} C.
+@example
+/* Declare the prototype for a general external function. */
+#if defined (__STDC__) || defined (WINDOWSNT)
+#define P_(proto) proto
+#else
+#define P_(proto) ()
+#endif
+@end example
-@node Source Language
-@section Using Languages Other Than C
+@node Conditional Compilation
+@section Conditional Compilation
-Using a language other than C is like using a non-standard feature: it
-will cause trouble for users. Even if GCC supports the other language,
-users may find it inconvenient to have to install the compiler for that
-other language in order to build your program. For example, if you
-write your program in C++, people will have to install the C++ compiler
-in order to compile your program. Thus, it is better if you write in C.
+When supporting configuration options already known when building your
+program we prefer using @code{if (... )} over conditional compilation,
+as in the former case the compiler is able to perform more extensive
+checking of all possible code paths.
-But there are three situations when there is no disadvantage in using
-some other language:
+For example, please write
-@itemize @bullet
-@item
-It is okay to use another language if your program contains an
-interpreter for that language.
+@smallexample
+ if (HAS_FOO)
+ ...
+ else
+ ...
+@end smallexample
-For example, if your program links with GUILE, it is ok to write part of
-the program in Scheme or another language supported by GUILE.
+@noindent
+instead of:
-@item
-It is okay to use another language in a tool specifically intended for
-use with that language.
+@smallexample
+ #ifdef HAS_FOO
+ ...
+ #else
+ ...
+ #endif
+@end smallexample
-This is okay because the only people who want to build the tool will be
-those who have installed the other language anyway.
+A modern compiler such as GCC will generate exactly the same code in
+both cases, and we have been using similar techniques with good success
+in several projects. Of course, the former method assumes that
+@code{HAS_FOO} is defined as either 0 or 1.
-@item
-If an application is of interest to a narrow community, then perhaps
-it's not important if the application is inconvenient to install.
-@end itemize
+While this is not a silver bullet solving all portability problems,
+and is not always appropriate, following this policy would have saved
+GCC developers many hours, or even days, per year.
-C has one other advantage over C++ and other compiled languages: more
-people know C, so more people will find it easy to read and modify the
-program if it is written in C.
+In the case of function-like macros like @code{REVERSIBLE_CC_MODE} in
+GCC which cannot be simply used in @code{if( ...)} statements, there is
+an easy workaround. Simply introduce another macro
+@code{HAS_REVERSIBLE_CC_MODE} as in the following example:
+
+@smallexample
+ #ifdef REVERSIBLE_CC_MODE
+ #define HAS_REVERSIBLE_CC_MODE 1
+ #else
+ #define HAS_REVERSIBLE_CC_MODE 0
+ #endif
+@end smallexample
@node Program Behavior
@chapter Program Behavior for All Programs
-This @value{CHAPTER} describes how to write robust software. It also
-describes general standards for error messages, the command line interface,
-and how libraries should behave.
+This chapter describes conventions for writing robust
+software. It also describes general standards for error messages, the
+command line interface, and how libraries should behave.
@menu
-* Semantics:: Writing robust programs
-* Libraries:: Library behavior
-* Errors:: Formatting error messages
-* User Interfaces:: Standards for command line interfaces
+* Non-GNU Standards:: We consider standards such as POSIX;
+ we don't "obey" them.
+* Semantics:: Writing robust programs.
+* Libraries:: Library behavior.
+* Errors:: Formatting error messages.
+* User Interfaces:: Standards about interfaces generally.
+* Graphical Interfaces:: Standards for graphical interfaces.
+* Command-Line Interfaces:: Standards for command line interfaces.
* Option Table:: Table of long options.
-* Memory Usage:: When and how to care about memory needs
+* Memory Usage:: When and how to care about memory needs.
+* File Usage:: Which files to use, and where.
@end menu
+@node Non-GNU Standards
+@section Non-GNU Standards
+
+The GNU Project regards standards published by other organizations as
+suggestions, not orders. We consider those standards, but we do not
+``obey'' them. In developing a GNU program, you should implement
+an outside standard's specifications when that makes the GNU system
+better overall in an objective sense. When it doesn't, you shouldn't.
+
+In most cases, following published standards is convenient for
+users---it means that their programs or scripts will work more
+portably. For instance, GCC implements nearly all the features of
+Standard C as specified by that standard. C program developers would
+be unhappy if it did not. And GNU utilities mostly follow
+specifications of POSIX.2; shell script writers and users would be
+unhappy if our programs were incompatible.
+
+But we do not follow either of these specifications rigidly, and there
+are specific points on which we decided not to follow them, so as to
+make the GNU system better for users.
+
+For instance, Standard C says that nearly all extensions to C are
+prohibited. How silly! GCC implements many extensions, some of which
+were later adopted as part of the standard. If you want these
+constructs to give an error message as ``required'' by the standard,
+you must specify @samp{--pedantic}, which was implemented only so that
+we can say ``GCC is a 100% implementation of the standard,'' not
+because there is any reason to actually use it.
+
+POSIX.2 specifies that @samp{df} and @samp{du} must output sizes by
+default in units of 512 bytes. What users want is units of 1k, so
+that is what we do by default. If you want the ridiculous behavior
+``required'' by POSIX, you must set the environment variable
+@samp{POSIXLY_CORRECT} (which was originally going to be named
+@samp{POSIX_ME_HARDER}).
+
+GNU utilities also depart from the letter of the POSIX.2 specification
+when they support long-named command-line options, and intermixing
+options with ordinary arguments. This minor incompatibility with
+POSIX is never a problem in practice, and it is very useful.
+
+In particular, don't reject a new feature, or remove an old one,
+merely because a standard says it is ``forbidden'' or ``deprecated.''
+
@node Semantics
@section Writing Robust Programs
+@cindex arbitrary limits on data
Avoid arbitrary limits on the length or number of @emph{any} data
structure, including file names, lines, files, and symbols, by allocating
all data structures dynamically. In most Unix utilities, ``long lines
are silently truncated''. This is not acceptable in a GNU utility.
+@cindex @code{NUL} characters
Utilities reading files should not drop NUL characters, or any other
-nonprinting characters @emph{including those with codes above 0177}. The
-only sensible exceptions would be utilities specifically intended for
-interface to certain types of printers that can't handle those characters.
-
+nonprinting characters @emph{including those with codes above 0177}.
+The only sensible exceptions would be utilities specifically intended
+for interface to certain types of terminals or printers
+that can't handle those characters.
+Whenever possible, try to make programs work properly with
+sequences of bytes that represent multibyte characters, using encodings
+such as UTF-8 and others.
+
+@cindex error messages
Check every system call for an error return, unless you know you wish to
ignore errors. Include the system error text (from @code{perror} or
equivalent) in @emph{every} error message resulting from a failing
utility. Just ``cannot open foo.c'' or ``stat failed'' is not
sufficient.
+@cindex @code{malloc} return value
+@cindex memory allocation failure
Check every call to @code{malloc} or @code{realloc} to see if it
returned zero. Check @code{realloc} even if you are making the block
smaller; in a system that rounds block sizes to a power of 2,
reader loop. This allows the user to kill other processes to free up
virtual memory, and then try the command again.
+@cindex command-line arguments, decoding
Use @code{getopt_long} to decode arguments, unless the argument syntax
makes this unreasonable.
as file directories, utmp, or the layout of kernel memory), since these
are less likely to work compatibly. If you need to find all the files
in a directory, use @code{readdir} or some other high-level interface.
-These will be supported compatibly by GNU.
+These are supported compatibly by GNU.
-By default, the GNU system will provide the signal handling functions of
-@sc{BSD} and of @sc{POSIX}. So GNU software should be written to use
-these.
+@cindex signal handling
+The preferred signal handling facilities are the BSD variant of
+@code{signal}, and the @sc{posix} @code{sigaction} function; the
+alternative USG @code{signal} interface is an inferior design.
+Nowadays, using the @sc{posix} signal functions may be the easiest way
+to make a program portable. If you use @code{signal}, then on GNU/Linux
+systems running GNU libc version 1, you should include
+@file{bsd/signal.h} instead of @file{signal.h}, so as to get BSD
+behavior. It is up to you whether to support systems where
+@code{signal} has only the USG behavior, or give up on them.
+
+@cindex impossible conditions
In error checks that detect ``impossible'' conditions, just abort.
There is usually no point in printing any message. These checks
indicate the existence of bugs. Whoever wants to fix the bugs will have
errors; if you try to return 256 as the exit status, the parent process
will see 0 as the status, and it will appear that the program succeeded.
+@cindex temporary files
+@cindex @code{TMPDIR} environment variable
If you make temporary files, check the @code{TMPDIR} environment
variable; if that variable is defined, use the specified directory
instead of @file{/tmp}.
+In addition, be aware that there is a possible security problem when
+creating temporary files in world-writable directories. In C, you can
+avoid this problem by creating temporary files in this manner:
+
+@example
+fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0600);
+@end example
+
+@noindent
+or by using the @code{mkstemps} function from libiberty.
+
+In bash, use @code{set -C} to avoid this problem.
+
@node Libraries
@section Library Behavior
+@cindex libraries
Try to make library functions reentrant. If they need to do dynamic
storage allocation, at least try to avoid any nonreentrancy aside from
other; then they can both go in the same file.
External symbols that are not documented entry points for the user
-should have names beginning with @samp{_}. They should also contain
-the chosen name prefix for the library, to prevent collisions with
-other libraries. These can go in the same files with user entry
-points if you like.
+should have names beginning with @samp{_}. The @samp{_} should be
+followed by the chosen name prefix for the library, to prevent
+collisions with other libraries. These can go in the same files with
+user entry points if you like.
Static functions and variables can be used as you like and need not
fit any naming convention.
@node Errors
@section Formatting Error Messages
+@cindex formatting error messages
+@cindex error messages, formatting
Error messages from compilers should look like this:
@var{source-file-name}:@var{lineno}: @var{message}
@end example
+@noindent
+If you want to mention the column number, use one of these formats:
+
+@example
+@var{source-file-name}:@var{lineno}:@var{column}: @var{message}
+@var{source-file-name}:@var{lineno}.@var{column}: @var{message}
+
+@end example
+
+@noindent
+Line numbers should start from 1 at the beginning of the file, and
+column numbers should start from 1 at the beginning of the line. (Both
+of these conventions are chosen for compatibility.) Calculate column
+numbers assuming that space and all ASCII printing characters have
+equal width, and assuming tab stops every 8 columns.
+
+The error message can also give both the starting and ending positions
+of the erroneous text. There are several formats so that you can
+avoid redundant information such as a duplicate line number.
+Here are the possible formats:
+
+@example
+@var{source-file-name}:@var{lineno-1}.@var{column-1}-@var{lineno-2}.@var{column-2}: @var{message}
+@var{source-file-name}:@var{lineno-1}.@var{column-1}-@var{column-2}: @var{message}
+@var{source-file-name}:@var{lineno-1}-@var{lineno-2}: @var{message}
+@end example
+
+@noindent
+When an error is spread over several files, you can use this format:
+
+@example
+@var{file-1}:@var{lineno-1}.@var{column-1}-@var{file-2}:@var{lineno-2}.@var{column-2}: @var{message}
+@end example
+
Error messages from other noninteractive programs should look like this:
@example
@noindent
when there is no relevant source file.
+If you want to mention the column number, use this format:
+
+@example
+@var{program}:@var{source-file-name}:@var{lineno}:@var{column}: @var{message}
+@end example
+
In an interactive program (one that is reading commands from a
terminal), it is better not to include the program name in an error
message. The place to indicate which program is running is in the
would do best to print error messages using the noninteractive style.)
The string @var{message} should not begin with a capital letter when
-it follows a program name and/or file name. Also, it should not end
-with a period.
+it follows a program name and/or file name, because that isn't the
+beginning of a sentence. (The sentence conceptually starts at the
+beginning of the line.) Also, it should not end with a period.
Error messages from interactive programs, and other messages such as
usage messages, should start with a capital letter. But they should not
end with a period.
@node User Interfaces
-@section Standards for Command Line Interfaces
+@section Standards for Interfaces Generally
+@cindex program name and its behavior
+@cindex behavior, dependent on program's name
Please don't make the behavior of a utility depend on the name used
to invoke it. It is useful sometimes to make a link to a utility
with a different name, and that should not change what it does.
Instead, use a run time option or a compilation switch or both
to select among the alternate behaviors.
+@cindex output device and program's behavior
Likewise, please don't make the behavior of the program depend on the
type of output device it is used with. Device independence is an
-important principle of the system's design; do not compromise it
-merely to save someone from typing an option now and then.
+important principle of the system's design; do not compromise it merely
+to save someone from typing an option now and then. (Variation in error
+message syntax when using a terminal is ok, because that is a side issue
+that people do not depend on.)
If you think one behavior is most useful when the output is to a
terminal, and another is most useful when the output is a file or a
like @code{ls} except that its default output format is always
multi-column format.
-It is a good idea to follow the @sc{POSIX} guidelines for the
+
+@node Graphical Interfaces
+@section Standards for Graphical Interfaces
+@cindex graphical user interface
+
+@cindex gtk+
+When you write a program that provides a graphical user interface,
+please make it work with X Windows and the GTK+ toolkit unless the
+functionality specifically requires some alternative (for example,
+``displaying jpeg images while in console mode'').
+
+In addition, please provide a command-line interface to control the
+functionality. (In many cases, the graphical user interface can be a
+separate program which invokes the command-line program.) This is
+so that the same jobs can be done from scripts.
+
+@cindex corba
+@cindex gnome
+Please also consider providing a CORBA interface (for use from GNOME), a
+library interface (for use from C), and perhaps a keyboard-driven
+console interface (for use by users from console mode). Once you are
+doing the work to provide the functionality and the graphical interface,
+these won't be much extra work.
+
+
+@node Command-Line Interfaces
+@section Standards for Command Line Interfaces
+@cindex command-line interface
+
+@findex getopt
+It is a good idea to follow the @sc{posix} guidelines for the
command-line options of a program. The easiest way to do this is to use
@code{getopt} to parse them. Note that the GNU version of @code{getopt}
will normally permit options anywhere among the arguments unless the
-special argument @samp{--} is used. This is not what @sc{POSIX}
+special argument @samp{--} is used. This is not what @sc{posix}
specifies; it is a GNU extension.
+@cindex long-named options
Please define long-named options that are equivalent to the
single-letter Unix-style options. We hope to make GNU more user
friendly this way. This is easy to do with the GNU function
(preferably @samp{-o} or @samp{--output}). Even if you allow an output
file name as an ordinary argument for compatibility, try to provide an
option as another way to specify it. This will lead to more consistency
-among GNU utilities, and fewer idiosyncracies for users to remember.
+among GNU utilities, and fewer idiosyncrasies for users to remember.
+@cindex standard command-line options
+@cindex options, standard command-line
+@cindex CGI programs, standard options for
+@cindex PATH_INFO, specifying standard options as
All programs should support two standard options: @samp{--version}
-and @samp{--help}.
+and @samp{--help}. CGI programs should accept these as command-line
+options, and also if given as the @env{PATH_INFO}; for instance,
+visiting @url{http://example.org/p.cgi/--help} in a browser should
+output the same information as invoking @samp{p.cgi --help} from the
+command line.
-@table @code
-@item --version
-This option should direct the program to information about its name,
-version, origin and legal status, all on standard output, and then exit
-successfully. Other options and arguments should be ignored once this
-is seen, and the program should not perform its normal function.
+@menu
+* --version:: The standard output for --version.
+* --help:: The standard output for --help.
+@end menu
+
+@node --version
+@subsection @option{--version}
+
+@cindex @samp{--version} output
+The standard @code{--version} option should direct the program to
+print information about its name, version, origin and legal status,
+all on standard output, and then exit successfully. Other options and
+arguments should be ignored once this is seen, and the program should
+not perform its normal function.
+
+@cindex canonical name of a program
+@cindex program's canonical name
The first line is meant to be easy for a program to parse; the version
number proper starts after the last space. In addition, it contains
the canonical name for this program, in this format:
program's version number, you can mention the package version number
just before the close-parenthesis.
-If you @strong{need} to mention the version numbers of libraries which
+If you @emph{need} to mention the version numbers of libraries which
are distributed separately from the package which contains this program,
you can do so by printing an additional line of version info for each
library you want to mention. Use the same format for these lines as for
copyright notice. If more than one copyright notice is called for, put
each on a separate line.
-Next should follow a brief statement that the program is free software,
-and that users are free to copy and change it on certain conditions. If
-the program is covered by the GNU GPL, say so here. Also mention that
-there is no warranty, to the extent permitted by law.
+Next should follow a line stating the license, preferably using one of
+abbrevations below, and a brief statement that the program is free
+software, and that users are free to copy and change it. Also mention
+that there is no warranty, to the extent permitted by law. See
+recommended wording below.
It is ok to finish the output with a list of the major authors of the
program, as a way of giving credit.
Here's an example of output that follows these rules:
@smallexample
-GNU Emacs 19.34.5
-Copyright (C) 1996 Free Software Foundation, Inc.
-GNU Emacs comes with NO WARRANTY,
-to the extent permitted by law.
-You may redistribute copies of GNU Emacs
-under the terms of the GNU General Public License.
-For more information about these matters,
-see the files named COPYING.
+GNU hello 2.3
+Copyright (C) 2007 Free Software Foundation, Inc.
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
@end smallexample
You should adapt this to your program, of course, filling in the proper
which changes were made---there's no need to list the years for previous
versions' changes. You don't have to mention the name of the program in
these notices, if that is inconvenient, since it appeared in the first
-line.
+line. (The rules are different for copyright notices in source files;
+@pxref{Copyright Notices,,,maintain,Information for GNU Maintainers}.)
-@item --help
-This option should output brief documentation for how to invoke the
-program, on standard output, then exit successfully. Other options and
-arguments should be ignored once this is seen, and the program should
-not perform its normal function.
+Translations of the above lines must preserve the validity of the
+copyright notices (@pxref{Internationalization}). If the translation's
+character set supports it, the @samp{(C)} should be replaced with the
+copyright symbol, as follows:
+
+@ifinfo
+(the official copyright symbol, which is the letter C in a circle);
+@end ifinfo
+@ifnotinfo
+@copyright{}
+@end ifnotinfo
+
+Write the word ``Copyright'' exactly like that, in English. Do not
+translate it into another language. International treaties recognize
+the English word ``Copyright''; translations into other languages do not
+have legal significance.
+
+Finally, here is the table of our suggested license abbreviations.
+Any abbreviation can be followed by @samp{v@var{version}[+]}, meaning
+that particular version, or later versions with the @samp{+}, as shown
+above.
+
+In the case of exceptions for extra permissions with the GPL, we use
+@samp{/} for a separator; the version number can follow the license
+abbreviation as usual, as in the examples below.
+
+@table @asis
+@item GPL
+GNU General Public License, @url{http://www.gnu.org/licenses/gpl.html}.
+
+@item LGPL
+GNU Lesser General Public License, @url{http://www.gnu.org/licenses/lgpl.html}.
+
+@item GPL/Guile
+GNU GPL with the exception for Guile; for example, GPLv3+/Guile means
+the GNU GPL version 3 or later, with the extra exception for Guile.
+
+GNU GPL with the exception for Ada.
+
+@item Apache
+The Apache Software Foundation license,
+@url{http://www.apache.org/licenses}.
+@item Artistic
+The Artistic license used for Perl, @url{http://www.perlfoundation.org/legal}.
+
+@item Expat
+The Expat license, @url{http://www.jclark.com/xml/copying.txt}.
+
+@item MPL
+The Mozilla Public License, @url{http://www.mozilla.org/MPL/}.
+
+@item OBSD
+The original (4-clause) BSD license, incompatible with the GNU GPL
+@url{http://www.xfree86.org/3.3.6/COPYRIGHT2.html#6}.
+
+@item PHP
+The license used for PHP, @url{http://www.php.net/license/}.
+
+@item public domain
+The non-license that is being in the public domain,
+@url{http://www.gnu.org/licenses/license-list.html#PublicDomain}.
+
+@item Python
+The license for Python, @url{http://www.python.org/2.0.1/license.html}.
+
+@item RBSD
+The revised (3-clause) BSD, compatible with the GNU GPL,
+@url{http://www.xfree86.org/3.3.6/COPYRIGHT2.html#5}.
+
+@item X11
+The simple non-copyleft license used for most versions of the X Window
+system, @url{http://www.xfree86.org/3.3.6/COPYRIGHT2.html#3}.
+
+@item Zlib
+The license for Zlib, @url{http://www.gzip.org/zlib/zlib_license.html}.
+
+@end table
+
+More information about these licenses and many more are on the GNU
+licensing web pages,
+@url{http://www.gnu.org/licenses/license-list.html}.
+
+
+@node --help
+@subsection @option{--help}
+
+@cindex @samp{--help} output
+
+The standard @code{--help} option should output brief documentation
+for how to invoke the program, on standard output, then exit
+successfully. Other options and arguments should be ignored once this
+is seen, and the program should not perform its normal function.
+
+@cindex address for bug reports
+@cindex bug reports
Near the end of the @samp{--help} option's output there should be a line
that says where to mail bug reports. It should have this format:
@example
Report bugs to @var{mailing-address}.
@end example
-@end table
+
@node Option Table
@section Table of Long Options
+@cindex long option names
+@cindex table of long options
Here is a table of long options used by GNU programs. It is surely
incomplete, but we aim to list all the options that a new program might
want to be compatible with. If you use names not already in the table,
-please send @email{gnu@@gnu.org} a list of them, with their
+please send @email{bug-standards@@gnu.org} a list of them, with their
meanings, so we can update the table.
@c Please leave newlines between items in this table; it's much easier
@item avoid-wraps
@samp{-n} in @code{wdiff}.
+@item background
+For server programs, run in the background.
+
@item backward-search
@samp{-B} in @code{ctags}.
@item dereference-args
@samp{-D} in @code{du}.
+@item device
+Specify an I/O device (special file name).
+
@item diacritics
@samp{-d} in @code{recode}.
@item force-prefix
@samp{-F} in @code{shar}.
+@item foreground
+For server programs, run in the foreground;
+in other words, don't do anything special to run the server
+in the background.
+
@item format
Used in @code{ls}, @code{time}, and @code{ptx}.
@item hide-control-chars
@samp{-q} in @code{ls}.
+@item html
+In @code{makeinfo}, output HTML.
+
@item idle
@samp{-u} in @code{who}.
@item info
@samp{-i}, @samp{-l}, and @samp{-m} in Finger.
+@item init-file
+In some programs, specify the name of the file to read as the user's
+init file.
+
@item initial
@samp{-i} in @code{expand}.
@item intermix-type
@samp{-p} in @code{shar}.
+@item iso-8601
+Used in @code{date}
+
@item jobs
@samp{-j} in Make.
Used in @code{su}.
@item machine
-No listing of which programs already use this;
-someone should check to
-see if any actually do, and tell @email{gnu@@gnu.org}.
+Used in @code{uname}.
@item macro-name
@samp{-M} in @code{ptx}.
@item no-sort
@samp{-p} in @code{nm}.
+@item no-splash
+Don't print a startup splash screen.
+
@item no-split
Used in @code{makeinfo}.
@item only-time
@samp{-F} in @code{gprof}.
+@item options
+@samp{-o} in @code{getopt}, @code{fdlist}, @code{fdmount},
+@code{fdmountd}, and @code{fdumount}.
+
@item output
In various programs, specify the output file name.
@item prompt
@samp{-p} in @code{ed}.
+@item proxy
+Specify an HTTP proxy.
+
@item query-user
@samp{-X} in @code{shar}.
@samp{-q} in Make.
@item quiet
-Used in many programs to inhibit the usual output. @strong{Note:} every
+Used in many programs to inhibit the usual output. Every
program accepting @samp{--quiet} should accept @samp{--silent} as a
synonym.
@item silent
Used in many programs to inhibit the usual output.
-@strong{Note:} every program accepting
+Every program accepting
@samp{--silent} should accept @samp{--quiet} as a synonym.
@item size
@samp{-s} in @code{ls}.
+@item socket
+Specify a file descriptor for a network server to use for its socket,
+instead of opening and binding a new socket. This provides a way to
+run, in a non-privileged process, a server that normally needs a
+reserved port number.
+
@item sort
Used in @code{ls}.
@item time
Used in @code{ls} and @code{touch}.
+@item timeout
+Specify how long to wait before giving up on some operation.
+
@item to-stdout
@samp{-O} in @code{tar}.
@node Memory Usage
@section Memory Usage
+@cindex memory usage
-If it typically uses just a few meg of memory, don't bother making any
+If a program typically uses just a few meg of memory, don't bother making any
effort to reduce memory usage. For example, if it is impractical for
other reasons to operate on files more than a few meg long, it is
-reasonable to read entire input files into core to operate on them.
+reasonable to read entire input files into memory to operate on them.
However, for programs such as @code{cat} or @code{tail}, that can
usefully operate on very large files, it is important to avoid using a
If a program works by lines and could be applied to arbitrary
user-supplied input files, it should keep only a line in memory, because
this is not very hard and users will want to be able to operate on input
-files that are bigger than will fit in core all at once.
+files that are bigger than will fit in memory all at once.
If your program creates complicated data structures, just make them in
-core and give a fatal error if @code{malloc} returns zero.
+memory and give a fatal error if @code{malloc} returns zero.
+
+@node File Usage
+@section File Usage
+@cindex file usage
+
+Programs should be prepared to operate when @file{/usr} and @file{/etc}
+are read-only file systems. Thus, if the program manages log files,
+lock files, backup files, score files, or any other files which are
+modified for internal purposes, these files should not be stored in
+@file{/usr} or @file{/etc}.
+
+There are two exceptions. @file{/etc} is used to store system
+configuration information; it is reasonable for a program to modify
+files in @file{/etc} when its job is to update the system configuration.
+Also, if the user explicitly asks to modify one file in a directory, it
+is reasonable for the program to store other files in the same
+directory.
@node Writing C
@chapter Making The Best Use of C
-This @value{CHAPTER} provides advice on how best to use the C language
+This chapter provides advice on how best to use the C language
when writing GNU software.
@menu
-* Formatting:: Formatting Your Source Code
-* Comments:: Commenting Your Work
-* Syntactic Conventions:: Clean Use of C Constructs
-* Names:: Naming Variables and Functions
-* System Portability:: Portability between different operating systems
-* CPU Portability:: Supporting the range of CPU types
-* System Functions:: Portability and ``standard'' library functions
-* Internationalization:: Techniques for internationalization
+* Formatting:: Formatting your source code.
+* Comments:: Commenting your work.
+* Syntactic Conventions:: Clean use of C constructs.
+* Names:: Naming variables, functions, and files.
+* System Portability:: Portability among different operating systems.
+* CPU Portability:: Supporting the range of CPU types.
+* System Functions:: Portability and ``standard'' library functions.
+* Internationalization:: Techniques for internationalization.
+* Character Set:: Use ASCII by default.
+* Quote Characters:: Use `...' in the C locale.
* Mmap:: How you can safely use @code{mmap}.
@end menu
@node Formatting
@section Formatting Your Source Code
+@cindex formatting source code
+@cindex open brace
+@cindex braces, in C source
It is important to put the open-brace that starts the body of a C
-function in column zero, and avoid putting any other open-brace or
-open-parenthesis or open-bracket in column zero. Several tools look
-for open-braces in column zero to find the beginnings of C functions.
-These tools will not work on code not formatted that way.
+function in column one, so that they will start a defun. Several
+tools look for open-braces in column one to find the beginnings of C
+functions. These tools will not work on code not formatted that way.
+
+Avoid putting open-brace, open-parenthesis or open-bracket in column
+one when they are inside a function, so that they won't start a defun.
+The open-brace that starts a @code{struct} body can go in column one
+if you find it useful to treat that definition as a defun.
It is also important for function definitions to start the name of the
-function in column zero. This helps people to search for function
+function in column one. This helps people to search for function
definitions, and may also help certain tools recognize them. Thus,
-the proper format is this:
+using Standard C syntax, the format is this:
@example
static char *
-concat (s1, s2) /* Name starts in column zero here */
- char *s1, *s2;
-@{ /* Open brace in column zero here */
+concat (char *s1, char *s2)
+@{
@dots{}
@}
@end example
@noindent
-or, if you want to use @sc{ansi} C, format the definition like this:
+or, if you want to use traditional C syntax, format the definition like
+this:
@example
static char *
-concat (char *s1, char *s2)
-@{
+concat (s1, s2) /* Name starts in column one here */
+ char *s1, *s2;
+@{ /* Open brace in column one here */
@dots{}
@}
@end example
-In @sc{ansi} C, if the arguments don't fit nicely on one line,
+In Standard C, if the arguments don't fit nicely on one line,
split it like this:
@example
@dots{}
@end example
-For the body of the function, we prefer code formatted like this:
+The rest of this section gives our recommendations for other aspects of
+C formatting style, which is also the default style of the @code{indent}
+program in version 1.2 and newer. It corresponds to the options
+
+@smallexample
+-nbad -bap -nbc -bbo -bl -bli2 -bls -ncdb -nce -cp1 -cs -di2
+-ndj -nfc1 -nfca -hnl -i2 -ip5 -lp -pcs -psl -nsc -nsob
+@end smallexample
+
+We don't think of these recommendations as requirements, because it
+causes no problems for users if two different programs have different
+formatting styles.
+
+But whatever style you use, please use it consistently, since a mixture
+of styles within one program tends to look ugly. If you are
+contributing changes to an existing program, please follow the style of
+that program.
+
+For the body of the function, our recommended style looks like this:
@example
if (x < foo (y, z))
@}
@end example
+@cindex spaces before open-paren
We find it easier to read a program when it has spaces before the
open-parentheses and after the commas. Especially after the commas.
When you split an expression into multiple lines, split it
before an operator, not after one. Here is the right way:
+@cindex expressions, splitting
@example
if (foo_this_is_long && bar > win (x, y, z)
&& remaining_condition)
Insert extra parentheses so that Emacs will indent the code properly.
For example, the following indentation looks nice if you do it by hand,
-but Emacs would mess it up:
@example
v = rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
+ rup->ru_stime.tv_sec*1000 + rup->ru_stime.tv_usec/1000;
@end example
-But adding a set of parentheses solves the problem:
+@noindent
+but Emacs would alter it. Adding a set of parentheses produces
+something that looks equally nice, and which Emacs will preserve:
@example
v = (rup->ru_utime.tv_sec*1000 + rup->ru_utime.tv_usec/1000
while (a > 0);
@end example
+@cindex formfeed
+@cindex control-L
Please use formfeed characters (control-L) to divide the program into
pages at logical places (but not within a function). It does not matter
just how long the pages are, since they do not have to fit on a printed
page. The formfeeds should appear alone on lines by themselves.
-
@node Comments
@section Commenting Your Work
+@cindex commenting
Every program should start with a comment saying briefly what it is for.
-Example: @samp{fmt - filter for simple filling of text}.
+Example: @samp{fmt - filter for simple filling of text}. This comment
+should be at the top of the source file containing the @samp{main}
+function of the program.
+
+Also, please write a brief comment at the start of each source file,
+with the file name and a line or two about the overall purpose of the
+file.
Please write the comments in a GNU program in English, because English
is the one language that nearly all programmers in all countries can
int truncate_lines;
@end example
+@cindex conditionals, comments for
+@cindex @code{#endif}, commenting
Every @samp{#endif} should have a comment, except in the case of short
conditionals (just a few lines) that are not nested. The comment should
state the condition of the conditional that is ending, @emph{including
@node Syntactic Conventions
@section Clean Use of C Constructs
-
-Please explicitly declare all arguments to functions.
-Don't omit them just because they are @code{int}s.
+@cindex syntactic conventions
+
+@cindex implicit @code{int}
+@cindex function argument, declaring
+Please explicitly declare the types of all objects. For example, you
+should explicitly declare all arguments to functions, and you should
+declare functions to return @code{int} rather than omitting the
+@code{int}.
+
+@cindex compiler warnings
+@cindex @samp{-Wall} compiler option
+Some programmers like to use the GCC @samp{-Wall} option, and change the
+code whenever it issues a warning. If you want to do this, then do.
+Other programmers prefer not to use @samp{-Wall}, because it gives
+warnings for valid and legitimate code which they do not want to change.
+If you want to do this, then do. The compiler should be your servant,
+not your master.
Declarations of external functions and functions to appear later in the
source file should all go in one place near the beginning of the file
should go in a header file. Don't put @code{extern} declarations inside
functions.
+@cindex temporary variables
It used to be common practice to use the same local variables (with
names like @code{tem}) over and over for different values within one
-function. Instead of doing this, it is better declare a separate local
+function. Instead of doing this, it is better to declare a separate local
variable for each distinct purpose, and give it a name which is
meaningful. This not only makes programs easier to understand, it also
facilitates optimization by good compilers. You can also move the
Don't use local variables or parameters that shadow global identifiers.
+@cindex multiple variables in a line
Don't declare multiple variables in one declaration that spans lines.
Start a new declaration on each line, instead. For example, instead
of this:
same declaration. Instead, declare the structure tag separately
and then use it to declare the variables or typedefs.
-Try to avoid assignments inside @code{if}-conditions. For example,
-don't write this:
+Try to avoid assignments inside @code{if}-conditions (assignments
+inside @code{while}-conditions are ok). For example, don't write
+this:
@example
if ((foo = (char *) malloc (sizeof *foo)) == 0)
fatal ("virtual memory exhausted");
@end example
+@pindex lint
Don't make the program ugly to placate @code{lint}. Please don't insert any
casts to @code{void}. Zero without a cast is perfectly fine as a null
pointer constant, except when calling a varargs function.
-@node Names
-@section Naming Variables and Functions
+@node Names
+@section Naming Variables, Functions, and Files
+@cindex names of variables, functions, and files
The names of global variables and functions in a program serve as
comments of a sort. So don't choose terse names---instead, look for
names that give useful information about the meaning of the variable or
Local variable names can be shorter, because they are used only within
one context, where (presumably) comments explain their purpose.
+Try to limit your use of abbreviations in symbol names. It is ok to
+make a few abbreviations, explain what they mean, and then use them
+frequently, but don't use lots of obscure abbreviations.
+
Please use underscores to separate words in a name, so that the Emacs
word commands can be useful within them. Stick to lower case; reserve
upper case for macros and @code{enum} constants, and for name-prefixes
@code{enum} rather than @samp{#define}. GDB knows about enumeration
constants.
-Use file names of 14 characters or less, to avoid creating gratuitous
-problems on older System V systems. You can use the program
-@code{doschk} to test for this. @code{doschk} also tests for potential
-name conflicts if the files were loaded onto an MS-DOS file
-system---something you may or may not care about.
+@cindex file-name limitations
+@pindex doschk
+You might want to make sure that none of the file names would conflict
+if the files were loaded onto an MS-DOS file system which shortens the
+names. You can use the program @code{doschk} to test for this.
+
+Some GNU programs were designed to limit themselves to file names of 14
+characters or less, to avoid file name conflicts if they are read into
+older System V systems. Please preserve this feature in the existing
+GNU programs that have it, but there is no need to do this in new GNU
+programs. @code{doschk} also reports file names longer than 14
+characters.
@node System Portability
@section Portability between System Types
+@cindex portability, between system types
In the Unix world, ``portability'' refers to porting to different Unix
versions. For a GNU program, this kind of portability is desirable, but
not paramount.
The primary purpose of GNU software is to run on top of the GNU kernel,
-compiled with the GNU C compiler, on various types of @sc{cpu}. The
-amount and kinds of variation among GNU systems on different @sc{cpu}s
-will be comparable to the variation among Linux-based GNU systems or
-among BSD systems today. So the kinds of portability that are absolutely
-necessary are quite limited.
-
-But many users do run GNU software on non-GNU Unix or Unix-like systems.
-So supporting a variety of Unix-like systems is desirable, although not
-paramount.
-
+compiled with the GNU C compiler, on various types of @sc{cpu}. So the
+kinds of portability that are absolutely necessary are quite limited.
+But it is important to support Linux-based GNU systems, since they
+are the form of GNU that is popular.
+
+Beyond that, it is good to support the other free operating systems
+(*BSD), and it is nice to support other Unix-like systems if you want
+to. Supporting a variety of Unix-like systems is desirable, although
+not paramount. It is usually not too hard, so you may as well do it.
+But you don't have to consider it an obligation, if it does turn out to
+be hard.
+
+@pindex autoconf
The easiest way to achieve portability to most Unix-like systems is to
use Autoconf. It's unlikely that your program needs to know more
information about the host platform than Autoconf can provide, simply
Avoid using the format of semi-internal data bases (e.g., directories)
when there is a higher-level alternative (@code{readdir}).
-As for systems that are not like Unix, such as MSDOS, Windows, the
-Macintosh, VMS, and MVS, supporting them is usually so much work that it
-is better if you don't.
-
-The planned GNU kernel is not finished yet, but you can tell which
-facilities it will provide by looking at the GNU C Library Manual. The
-GNU kernel is based on Mach, so the features of Mach will also be
-available. However, if you use Mach features, you'll probably have
-trouble debugging your program today.
+@cindex non-@sc{posix} systems, and portability
+As for systems that are not like Unix, such as MSDOS, Windows, VMS, MVS,
+and older Macintosh systems, supporting them is often a lot of work.
+When that is the case, it is better to spend your time adding features
+that will be useful on GNU and GNU/Linux, rather than on supporting
+other incompatible systems.
+
+If you do support Windows, please do not abbreviate it as ``win''. In
+hacker terminology, calling something a ``win'' is a form of praise.
+You're free to praise Microsoft Windows on your own if you want, but
+please don't do this in GNU packages. Instead of abbreviating
+``Windows'' to ``un'', you can write it in full or abbreviate it to
+``woe'' or ``w''. In GNU Emacs, for instance, we use @samp{w32} in
+file names of Windows-specific files, but the macro for Windows
+conditionals is called @code{WINDOWSNT}.
+
+It is a good idea to define the ``feature test macro''
+@code{_GNU_SOURCE} when compiling your C files. When you compile on GNU
+or GNU/Linux, this will enable the declarations of GNU library extension
+functions, and that will usually give you a compiler error message if
+you define the same function names in some other way in your program.
+(You don't have to actually @emph{use} these functions, if you prefer
+to make the program more portable to other systems.)
+
+But whether or not you use these GNU extensions, you should avoid
+using their names for any other meanings. Doing so would make it hard
+to move your code into other GNU programs.
@node CPU Portability
@section Portability between @sc{cpu}s
+@cindex data types, and portability
+@cindex portability, and data types
Even GNU systems will differ because of differences among @sc{cpu}
types---for example, difference in byte ordering and alignment
requirements. It is absolutely essential to handle these differences.
@code{int} will be less than 32 bits. We don't support 16-bit machines
in GNU.
+Similarly, don't make any effort to cater to the possibility that
+@code{long} will be smaller than predefined types like @code{size_t}.
+For example, the following code is ok:
+
+@example
+printf ("size = %lu\n", (unsigned long) sizeof array);
+printf ("diff = %ld\n", (long) (pointer2 - pointer1));
+@end example
+
+1989 Standard C requires this to work, and we know of only one
+counterexample: 64-bit programs on Microsoft Windows. We will
+leave it to those who want to port GNU programs to that environment
+to figure out how to do it.
+
+Predefined file-size types like @code{off_t} are an exception: they are
+longer than @code{long} on many platforms, so code like the above won't
+work with them. One way to print an @code{off_t} value portably is to
+print its digits yourself, one by one.
+
Don't assume that the address of an @code{int} object is also the
address of its least-significant byte. This is false on big-endian
machines. Thus, don't make the following mistake:
@example
int c;
@dots{}
-while ((c = getchar()) != EOF)
- write(file_descriptor, &c, 1);
+while ((c = getchar ()) != EOF)
+ write (file_descriptor, &c, 1);
+@end example
+
+@noindent Instead, use @code{unsigned char} as follows. (The @code{unsigned}
+is for portability to unusual systems where @code{char} is signed and
+where there is integer overflow checking.)
+
+@example
+int c;
+while ((c = getchar ()) != EOF)
+ @{
+ unsigned char u = c;
+ write (file_descriptor, &u, 1);
+ @}
@end example
-When calling functions, you need not worry about the difference between
-pointers of various types, or between pointers and integers. On most
-machines, there's no difference anyway. As for the few machines where
-there is a difference, all of them support @sc{ansi} C, so you can use
-prototypes (conditionalized to be active only in @sc{ansi} C) to make
-the code work on those systems.
+It used to be ok to not worry about the difference between pointers
+and integers when passing arguments to functions. However, on most
+modern 64-bit machines pointers are wider than @code{int}.
+Conversely, integer types like @code{long long int} and @code{off_t}
+are wider than pointers on most modern 32-bit machines. Hence it's
+often better nowadays to use prototypes to define functions whose
+argument types are not trivial.
+
+In particular, if functions accept varying argument counts or types
+they should be declared using prototypes containing @samp{...} and
+defined using @file{stdarg.h}. For an example of this, please see the
+@uref{http://www.gnu.org/software/gnulib/, Gnulib} error module, which
+declares and defines the following function:
+
+@example
+/* Print a message with `fprintf (stderr, FORMAT, ...)';
+ if ERRNUM is nonzero, follow it with ": " and strerror (ERRNUM).
+ If STATUS is nonzero, terminate the program with `exit (STATUS)'. */
+
+void error (int status, int errnum, const char *format, ...);
+@end example
-In certain cases, it is ok to pass integer and pointer arguments
-indiscriminately to the same function, and use no prototype on any
-system. For example, many GNU programs have error-reporting functions
-that pass their arguments along to @code{printf} and friends:
+A simple way to use the Gnulib error module is to obtain the two
+source files @file{error.c} and @file{error.h} from the Gnulib library
+source code repository at
+@uref{http://savannah.gnu.org/cgi-bin/viewcvs/gnulib/gnulib/lib/}.
+Here's a sample use:
@example
-error (s, a1, a2, a3)
- char *s;
- int a1, a2, a3;
+#include "error.h"
+#include <errno.h>
+#include <stdio.h>
+
+char *program_name = "myprogram";
+
+FILE *
+xfopen (char const *name)
@{
- fprintf (stderr, "error: ");
- fprintf (stderr, s, a1, a2, a3);
+ FILE *fp = fopen (name, "r");
+ if (! fp)
+ error (1, errno, "cannot read %s", name);
+ return fp;
@}
@end example
-@noindent
-In practice, this works on all machines, and it is much simpler than any
-``correct'' alternative. Be sure @emph{not} to use a prototype
-for such functions.
-
-However, avoid casting pointers to integers unless you really need to.
-These assumptions really reduce portability, and in most programs they
-are easy to avoid. In the cases where casting pointers to integers is
-essential---such as, a Lisp interpreter which stores type information as
-well as an address in one word---it is ok to do so, but you'll have to
-make explicit provisions to handle different word sizes.
+@cindex casting pointers to integers
+Avoid casting pointers to integers if you can. Such casts greatly
+reduce portability, and in most programs they are easy to avoid. In the
+cases where casting pointers to integers is essential---such as, a Lisp
+interpreter which stores type information as well as an address in one
+word---you'll have to make explicit provisions to handle different word
+sizes. You will also need to make provision for systems in which the
+normal range of addresses you can get from @code{malloc} starts far away
+from zero.
@node System Functions
@section Calling System Functions
+@cindex library functions, and portability
+@cindex portability, and library functions
-C implementations differ substantially. @sc{ansi} C reduces but does not
-eliminate the incompatibilities; meanwhile, many users wish to compile
-GNU software with pre-@sc{ansi} compilers. This chapter gives
-recommendations for how to use the more or less standard C library
-functions to avoid unnecessary loss of portability.
+C implementations differ substantially. Standard C reduces but does
+not eliminate the incompatibilities; meanwhile, many GNU packages still
+support pre-standard compilers because this is not hard to do. This
+chapter gives recommendations for how to use the more-or-less standard C
+library functions to avoid unnecessary loss of portability.
@itemize @bullet
@item
-Don't use the value of @code{sprintf}. It returns the number of
+Don't use the return value of @code{sprintf}. It returns the number of
characters written on some systems, but not on all systems.
+@item
+Be aware that @code{vfprintf} is not always available.
+
@item
@code{main} should be declared to return type @code{int}. It should
terminate either by calling @code{exit} or by returning the integer
status code; make sure it cannot ever return an undefined value.
+@cindex declaration for system functions
@item
Don't declare system functions explicitly.
@item
If you must declare a system function, don't specify the argument types.
-Use an old-style declaration, not an @sc{ansi} prototype. The more you
+Use an old-style declaration, not a Standard C prototype. The more you
specify about the function, the more likely a conflict.
@item
@code{realloc}---or put these declarations in configuration files
specific to those systems.
+@cindex string library functions
@item
The string functions require special treatment. Some Unix systems have
a header file @file{string.h}; others have @file{strings.h}. Neither
If you don't include either strings file, you can't get declarations for
the string functions from the header file in the usual way.
-That causes less of a problem than you might think. The newer @sc{ansi}
+That causes less of a problem than you might think. The newer standard
string functions should be avoided anyway because many systems still
don't support them. The string functions you can use are these:
You should pick a single pair of names and use it throughout your
program. (Nowadays, it is better to choose @code{strchr} and
-@code{strrchr} for new programs, since those are the standard @sc{ansi}
+@code{strrchr} for new programs, since those are the standard
names.) Declare both of those names as functions returning @code{char
*}. On systems which don't support those names, define them as macros
in terms of the other pair. For example, here is what to put at the
@node Internationalization
@section Internationalization
+@cindex internationalization
+@pindex gettext
GNU has a library called GNU gettext that makes it easy to translate the
messages in a program into various languages. You should use this
library in every program. Use English for the messages as they appear
name} for the package. The text domain name is used to separate the
translations for this package from the translations for other packages.
Normally, the text domain name should be the same as the name of the
-package---for example, @samp{fileutils} for the GNU file utilities.
+package---for example, @samp{coreutils} for the GNU core utilities.
+@cindex message text, and internationalization
To enable gettext to work well, avoid writing code that makes
assumptions about the structure of words or sentences. When you want
the precise text of a sentence to vary depending on the data, use two or
Here is an example of what not to do:
+@smallexample
+printf ("%s is full", capacity > 5000000 ? "disk" : "floppy disk");
+@end smallexample
+
+If you apply gettext to all strings, like this,
+
+@smallexample
+printf (gettext ("%s is full"),
+ capacity > 5000000 ? gettext ("disk") : gettext ("floppy disk"));
+@end smallexample
+
+@noindent
+the translator will hardly know that "disk" and "floppy disk" are meant to
+be substituted in the other string. Worse, in some languages (like French)
+the construction will not work: the translation of the word "full" depends
+on the gender of the first part of the sentence; it happens to be not the
+same for "disk" as for "floppy disk".
+
+Complete sentences can be translated without problems:
+
+@example
+printf (capacity > 5000000 ? gettext ("disk is full")
+ : gettext ("floppy disk is full"));
+@end example
+
+A similar problem appears at the level of sentence structure with this
+code:
+
+@example
+printf ("# Implicit rule search has%s been done.\n",
+ f->tried_implicit ? "" : " not");
+@end example
+
+@noindent
+Adding @code{gettext} calls to this code cannot give correct results for
+all languages, because negation in some languages requires adding words
+at more than one place in the sentence. By contrast, adding
+@code{gettext} calls does the job straightforwardly if the code starts
+out like this:
+
+@example
+printf (f->tried_implicit
+ ? "# Implicit rule search has been done.\n",
+ : "# Implicit rule search has not been done.\n");
+@end example
+
+Another example is this one:
+
@example
printf ("%d file%s processed", nfiles,
nfiles != 1 ? "s" : "");
@end example
@noindent
-The problem with that example is that it assumes that plurals are made
+The problem with this example is that it assumes that plurals are made
by adding `s'. If you apply gettext to the format string, like this,
@example
@noindent
the message can use different words, but it will still be forced to use
-`s' for the plural. Here is a better way:
+`s' for the plural. Here is a better way, with gettext being applied to
+the two strings independently:
@example
-printf ((nfiles != 1 ? "%d files processed"
- : "%d file processed"),
+printf ((nfiles != 1 ? gettext ("%d files processed")
+ : gettext ("%d file processed")),
nfiles);
@end example
@noindent
-This way, you can apply gettext to each of the two strings
-independently:
+But this still doesn't work for languages like Polish, which has three
+plural forms: one for nfiles == 1, one for nfiles == 2, 3, 4, 22, 23, 24, ...
+and one for the rest. The GNU @code{ngettext} function solves this problem:
@example
-printf ((nfiles != 1 ? gettext ("%d files processed")
- : gettext ("%d file processed")),
+printf (ngettext ("%d files processed", "%d file processed", nfiles),
nfiles);
@end example
-@noindent
-This can be any method of forming the plural of the word for ``file'', and
-also handles languages that require agreement in the word for
-``processed''.
-A similar problem appears at the level of sentence structure with this
-code:
+@node Character Set
+@section Character Set
+@cindex character set
+@cindex encodings
+@cindex ASCII characters
+@cindex non-ASCII characters
-@example
-printf ("# Implicit rule search has%s been done.\n",
- f->tried_implicit ? "" : " not");
-@end example
+Sticking to the ASCII character set (plain text, 7-bit characters) is
+preferred in GNU source code comments, text documents, and other
+contexts, unless there is good reason to do something else because of
+the application domain. For example, if source code deals with the
+French Revolutionary calendar, it is OK if its literal strings contain
+accented characters in month names like ``Flor@'eal''. Also, it is OK
+to use non-ASCII characters to represent proper names of contributors in
+change logs (@pxref{Change Logs}).
-@noindent
-Adding @code{gettext} calls to this code cannot give correct results for
-all languages, because negation in some languages requires adding words
-at more than one place in the sentence. By contrast, adding
-@code{gettext} calls does the job straightfowardly if the code starts
-out like this:
+If you need to use non-ASCII characters, you should normally stick with
+one encoding, as one cannot in general mix encodings reliably.
+
+
+@node Quote Characters
+@section Quote Characters
+@cindex quote characters
+@cindex locale-specific quote characters
+@cindex left quote
+@cindex grave accent
+
+In the C locale, GNU programs should stick to plain ASCII for quotation
+characters in messages to users: preferably 0x60 (@samp{`}) for left
+quotes and 0x27 (@samp{'}) for right quotes. It is ok, but not
+required, to use locale-specific quotes in other locales.
+
+The @uref{http://www.gnu.org/software/gnulib/, Gnulib} @code{quote} and
+@code{quotearg} modules provide a reasonably straightforward way to
+support locale-specific quote characters, as well as taking care of
+other issues, such as quoting a filename that itself contains a quote
+character. See the Gnulib documentation for usage details.
+
+In any case, the documentation for your program should clearly specify
+how it does quoting, if different than the preferred method of @samp{`}
+and @samp{'}. This is especially important if the output of your
+program is ever likely to be parsed by another program.
+
+Quotation characters are a difficult area in the computing world at
+this time: there are no true left or right quote characters in Latin1;
+the @samp{`} character we use was standardized there as a grave
+accent. Moreover, Latin1 is still not universally usable.
+
+Unicode contains the unambiguous quote characters required, and its
+common encoding UTF-8 is upward compatible with Latin1. However,
+Unicode and UTF-8 are not universally well-supported, either.
+
+This may change over the next few years, and then we will revisit
+this.
-@example
-printf (f->tried_implicit
- ? "# Implicit rule search has been done.\n",
- : "# Implicit rule search has not been done.\n");
-@end example
@node Mmap
@section Mmap
+@findex mmap
Don't assume that @code{mmap} either works on all files or fails
for all files. It may work on some files and fail on others.
@node Documentation
@chapter Documenting Programs
+@cindex documentation
+
+A GNU program should ideally come with full free documentation, adequate
+for both reference and tutorial purposes. If the package can be
+programmed or extended, the documentation should cover programming or
+extending it, as well as just using it.
@menu
* GNU Manuals:: Writing proper manuals.
+* Doc Strings and Manuals:: Compiling doc strings doesn't make a manual.
* Manual Structure Details:: Specific structure conventions.
+* License for Manuals:: Writing the distribution terms for a manual.
+* Manual Credits:: Giving credit to documentation contributors.
+* Printed Manuals:: Mentioning the printed manual.
* NEWS File:: NEWS files supplement manuals.
-* Change Logs:: Recording Changes
+* Change Logs:: Recording changes.
* Man Pages:: Man pages are secondary.
* Reading other Manuals:: How far you can go in learning
from other manuals.
@node GNU Manuals
@section GNU Manuals
-The preferred way to document part of the GNU system is to write a
-manual in the Texinfo formatting language. See the Texinfo manual,
-either the hardcopy, or the on-line version available through
-@code{info} or the Emacs Info subsystem (@kbd{C-h i}).
-
-Programmers often find it most natural to structure the documentation
-following the structure of the implementation, which they know. But
-this structure is not necessarily good for explaining how to use the
-program; it may be irrelevant and confusing for a user.
-
-At every level, from the sentences in a paragraph to the grouping of
-topics into separate manuals, the right way to structure documentation
-is according to the concepts and questions that a user will have in mind
-when reading it. Sometimes this structure of ideas matches the
+The preferred document format for the GNU system is the Texinfo
+formatting language. Every GNU package should (ideally) have
+documentation in Texinfo both for reference and for learners. Texinfo
+makes it possible to produce a good quality formatted book, using
+@TeX{}, and to generate an Info file. It is also possible to generate
+HTML output from Texinfo source. See the Texinfo manual, either the
+hardcopy, or the on-line version available through @code{info} or the
+Emacs Info subsystem (@kbd{C-h i}).
+
+Nowadays some other formats such as Docbook and Sgmltexi can be
+converted automatically into Texinfo. It is ok to produce the Texinfo
+documentation by conversion this way, as long as it gives good results.
+
+Make sure your manual is clear to a reader who knows nothing about the
+topic and reads it straight through. This means covering basic topics
+at the beginning, and advanced topics only later. This also means
+defining every specialized term when it is first used.
+
+Programmers tend to carry over the structure of the program as the
+structure for its documentation. But this structure is not
+necessarily good for explaining how to use the program; it may be
+irrelevant and confusing for a user.
+
+Instead, the right way to structure documentation is according to the
+concepts and questions that a user will have in mind when reading it.
+This principle applies at every level, from the lowest (ordering
+sentences in a paragraph) to the highest (ordering of chapter topics
+within the manual). Sometimes this structure of ideas matches the
structure of the implementation of the software being documented---but
-often they are different. Often the most important part of learning to
-write good documentation is learning to notice when you are structuring
-the documentation like the implementation, and think about better
-alternatives.
+often they are different. An important part of learning to write good
+documentation is to learn to notice when you have unthinkingly
+structured the documentation like the implementation, stop yourself,
+and look for better alternatives.
For example, each program in the GNU system probably ought to be
documented in one manual; but this does not mean each program should
programs, as well as @code{cmp}. By documenting these programs
together, we can make the whole subject clearer.
-The manual which discusses a program should document all of the
-program's command-line options and all of its commands. It should give
-examples of their use. But don't organize the manual as a list of
-features. Instead, organize it logically, by subtopics. Address the
-questions that a user will ask when thinking about the job that the
-program does.
+The manual which discusses a program should certainly document all of
+the program's command-line options and all of its commands. It should
+give examples of their use. But don't organize the manual as a list
+of features. Instead, organize it logically, by subtopics. Address
+the questions that a user will ask when thinking about the job that
+the program does. Don't just tell the reader what each feature can
+do---say what jobs it is good for, and show how to use it for those
+jobs. Explain what is recommended usage, and what kinds of usage
+users should avoid.
In general, a GNU manual should serve both as tutorial and reference.
It should be set up for convenient access to each topic through Info,
and for reading straight through (appendixes aside). A GNU manual
should give a good introduction to a beginner reading through from the
start, and should also provide all the details that hackers want.
+The Bison manual is a good example of this---please take a look at it
+to see what we mean.
That is not as hard as it first sounds. Arrange each chapter as a
logical breakdown of its topic, but order the sections, and write their
the framework for a beginner to understand the rest of the manual. The
Bison manual provides a good example of how to do this.
+To serve as a reference, a manual should have an Index that list all the
+functions, variables, options, and important concepts that are part of
+the program. One combined Index should do for a short manual, but
+sometimes for a complex package it is better to use multiple indices.
+The Texinfo manual includes advice on preparing good index entries, see
+@ref{Index Entries, , Making Index Entries, texinfo, GNU Texinfo}, and
+see @ref{Indexing Commands, , Defining the Entries of an
+Index, texinfo, GNU Texinfo}.
+
Don't use Unix man pages as a model for how to write GNU documentation;
most of them are terse, badly structured, and give inadequate
-explanation of the underlying concepts. (There are, of course
-exceptions.) Also Unix man pages use a particular format which is
+explanation of the underlying concepts. (There are, of course, some
+exceptions.) Also, Unix man pages use a particular format which is
different from what we use in GNU manuals.
+Please include an email address in the manual for where to report
+bugs @emph{in the text of the manual}.
+
Please do not use the term ``pathname'' that is used in Unix
documentation; use ``file name'' (two words) instead. We use the term
-``path'' only for search paths, which are lists of file names.
-
-Please do not use the term ``illegal'' to refer to erroneous input to a
-computer program. Please use ``invalid'' for this, and reserve the term
-``illegal'' for violations of law.
+``path'' only for search paths, which are lists of directory names.
+
+Please do not use the term ``illegal'' to refer to erroneous input to
+a computer program. Please use ``invalid'' for this, and reserve the
+term ``illegal'' for activities prohibited by law.
+
+Please do not write @samp{()} after a function name just to indicate
+it is a function. @code{foo ()} is not a function, it is a function
+call with no arguments.
+
+@node Doc Strings and Manuals
+@section Doc Strings and Manuals
+
+Some programming systems, such as Emacs, provide a documentation string
+for each function, command or variable. You may be tempted to write a
+reference manual by compiling the documentation strings and writing a
+little additional text to go around them---but you must not do it. That
+approach is a fundamental mistake. The text of well-written
+documentation strings will be entirely wrong for a manual.
+
+A documentation string needs to stand alone---when it appears on the
+screen, there will be no other text to introduce or explain it.
+Meanwhile, it can be rather informal in style.
+
+The text describing a function or variable in a manual must not stand
+alone; it appears in the context of a section or subsection. Other text
+at the beginning of the section should explain some of the concepts, and
+should often make some general points that apply to several functions or
+variables. The previous descriptions of functions and variables in the
+section will also have given information about the topic. A description
+written to stand alone would repeat some of that information; this
+redundancy looks bad. Meanwhile, the informality that is acceptable in
+a documentation string is totally unacceptable in a manual.
+
+The only good way to use documentation strings in writing a good manual
+is to use them as a source of information for writing good text.
@node Manual Structure Details
@section Manual Structure Details
+@cindex manual structure
The title page of the manual should state the version of the programs or
packages documented in the manual. The Top node of the manual should
frequently than or independent of the program, also state a version
number for the manual in both of these places.
-Each program documented in the manual should should have a node named
+Each program documented in the manual should have a node named
@samp{@var{program} Invocation} or @samp{Invoking @var{program}}. This
node (together with its subnodes, if any) should describe the program's
command line arguments and how to run it (the sort of information people
-would look in a man page for). Start with an @samp{@@example}
+would look for in a man page). Start with an @samp{@@example}
containing a template for all the options and arguments that the program
uses.
the above patterns. This identifies the node which that item points to
as the node for this purpose, regardless of the node's actual name.
-There will be automatic features for specifying a program name and
-quickly reading just this part of its manual.
+The @samp{--usage} feature of the Info reader looks for such a node
+or menu item in order to find the relevant text, so it is essential
+for every Texinfo file to have one.
If one manual describes several programs, it should have such a node for
-each program described.
+each program described in the manual.
+
+@node License for Manuals
+@section License for Manuals
+@cindex license for manuals
+
+Please use the GNU Free Documentation License for all GNU manuals that
+are more than a few pages long. Likewise for a collection of short
+documents---you only need one copy of the GNU FDL for the whole
+collection. For a single short document, you can use a very permissive
+non-copyleft license, to avoid taking up space with a long license.
+
+See @uref{http://www.gnu.org/copyleft/fdl-howto.html} for more explanation
+of how to employ the GFDL.
+
+Note that it is not obligatory to include a copy of the GNU GPL or GNU
+LGPL in a manual whose license is neither the GPL nor the LGPL. It can
+be a good idea to include the program's license in a large manual; in a
+short manual, whose size would be increased considerably by including
+the program's license, it is probably better not to include it.
+
+@node Manual Credits
+@section Manual Credits
+@cindex credits for manuals
+
+Please credit the principal human writers of the manual as the authors,
+on the title page of the manual. If a company sponsored the work, thank
+the company in a suitable place in the manual, but do not cite the
+company as an author.
+
+@node Printed Manuals
+@section Printed Manuals
+
+The FSF publishes some GNU manuals in printed form. To encourage sales
+of these manuals, the on-line versions of the manual should mention at
+the very start that the printed manual is available and should point at
+information for getting it---for instance, with a link to the page
+@url{http://www.gnu.org/order/order.html}. This should not be included
+in the printed manual, though, because there it is redundant.
+
+It is also useful to explain in the on-line forms of the manual how the
+user can print out the manual from the sources.
@node NEWS File
@section The NEWS File
+@cindex @file{NEWS} file
In addition to its manual, the package should have a file named
@file{NEWS} which contains a list of user-visible changes worth
@node Change Logs
@section Change Logs
+@cindex change logs
Keep a change log to describe all the changes made to program source
files. The purpose of this is so that people investigating bugs in the
history of how the conflicting concepts arose and who they came from.
@menu
-* Change Log Concepts::
-* Style of Change Logs::
-* Simple Changes::
-* Conditional Changes::
+* Change Log Concepts::
+* Style of Change Logs::
+* Simple Changes::
+* Conditional Changes::
+* Indicating the Part Changed::
@end menu
@node Change Log Concepts
Another alternative is to record change log information with a version
control system such as RCS or CVS. This can be converted automatically
-to a @file{ChangeLog} file.
+to a @file{ChangeLog} file using @code{rcs2log}; in Emacs, the command
+@kbd{C-x v a} (@code{vc-update-change-log}) does the job.
There's no need to describe the full purpose of the changes or how they
work together. If you think that a change calls for explanation, you're
you add a function, because there should be a comment before the
function definition to explain what it does.
+In the past, we recommended not mentioning changes in non-software
+files (manuals, help files, etc.) in change logs. However, we've been
+advised that it is a good idea to include them, for the sake of
+copyright records.
+
However, sometimes it is useful to write one line to describe the
overall purpose of a batch of changes.
@node Style of Change Logs
@subsection Style of Change Logs
+@cindex change logs, style
-Here are some examples of change log entries:
+Here are some simple examples of change log entries, starting with the
+header line that says who made the change and when it was installed,
+followed by descriptions of specific changes. (These examples are
+drawn from Emacs and GCC.)
@example
+1998-08-17 Richard Stallman <rms@@gnu.org>
+
* register.el (insert-register): Return nil.
(jump-to-register): Likewise.
then don't put blank lines between them. Then you can omit the file
name and the asterisk when successive entries are in the same file.
+Break long lists of function names by closing continued lines with
+@samp{)}, rather than @samp{,}, and opening the continuation with
+@samp{(} as in this example:
+
+@example
+* keyboard.c (menu_bar_items, tool_bar_items)
+(Fexecute_extended_command): Deal with `keymap' property.
+@end example
+
+When you install someone else's changes, put the contributor's name in
+the change log entry rather than in the text of the entry. In other
+words, write this:
+
+@example
+2002-07-14 John Doe <jdoe@@gnu.org>
+
+ * sewing.c: Make it sew.
+@end example
+
+@noindent
+rather than this:
+
+@example
+2002-07-14 Usual Maintainer <usual@@gnu.org>
+
+ * sewing.c: Make it sew. Patch by jdoe@@gnu.org.
+@end example
+
+As for the date, that should be the date you applied the change.
+
@node Simple Changes
@subsection Simple Changes
log.
When you change the calling sequence of a function in a simple fashion,
-and you change all the callers of the function, there is no need to make
-individual entries for all the callers that you changed. Just write in
-the entry for the function being called, ``All callers changed.''
+and you change all the callers of the function to use the new calling
+sequence, there is no need to make individual entries for all the
+callers that you changed. Just write in the entry for the function
+being called, ``All callers changed''---like this:
@example
* keyboard.c (Fcommand_execute): New arg SPECIAL.
entry for the file, without mentioning the functions. Just ``Doc
fixes'' is enough for the change log.
-There's no need to make change log entries for documentation files.
-This is because documentation is not susceptible to bugs that are hard
-to fix. Documentation does not consist of parts that must interact in a
-precisely engineered fashion. To correct an error, you need not know
-the history of the erroneous passage; it is enough to compare what the
-documentation says with the way the program actually works.
+There's no technical need to make change log entries for documentation
+files. This is because documentation is not susceptible to bugs that
+are hard to fix. Documentation does not consist of parts that must
+interact in a precisely engineered fashion. To correct an error, you
+need not know the history of the erroneous passage; it is enough to
+compare what the documentation says with the way the program actually
+works.
+
+However, you should keep change logs for documentation files when the
+project gets copyright assignments from its contributors, so as to
+make the records of authorship more accurate.
@node Conditional Changes
@subsection Conditional Changes
+@cindex conditional changes, and change logs
+@cindex change logs, conditional changes
C programs often contain compile-time @code{#if} conditionals. Many
changes are conditional; sometimes you add a new definition which is
(gethostname) [!HAVE_SOCKETS]: Replace with winsock version.
@end example
+@node Indicating the Part Changed
+@subsection Indicating the Part Changed
+
+Indicate the part of a function which changed by using angle brackets
+enclosing an indication of what the changed part does. Here is an entry
+for a change in the part of the function @code{sh-while-getopts} that
+deals with @code{sh} commands:
+
+@example
+* progmodes/sh-script.el (sh-while-getopts) <sh>: Handle case that
+user-specified option string is empty.
+@end example
+
+
@node Man Pages
@section Man Pages
+@cindex man pages
In the GNU project, man pages are secondary. It is not necessary or
expected for every GNU program to have a man page, but some of them do.
is more authoritative. The note should say how to access the Texinfo
documentation.
+Be sure that man pages include a copyright statement and free
+license. The simple all-permissive license is appropriate for simple
+man pages:
+
+@example
+Copying and distribution of this file, with or without modification,
+are permitted in any medium without royalty provided the copyright
+notice and this notice are preserved.
+@end example
+
+For long man pages, with enough explanation and documentation that
+they can be considered true manuals, use the GFDL (@pxref{License for
+Manuals}).
+
+Finally, the GNU help2man program
+(@uref{http://www.gnu.org/software/help2man/}) is one way to automate
+generation of a man page, in this case from @option{--help} output.
+This is sufficient in many cases.
+
@node Reading other Manuals
@section Reading other Manuals
@node Managing Releases
@chapter The Release Process
+@cindex releasing
Making a release is more than just bundling up your source files in a
tar file and putting it up for FTP. You should set up your software so
all GNU software.
@menu
-* Configuration:: How Configuration Should Work
-* Makefile Conventions:: Makefile Conventions
-* Releases:: Making Releases
+* Configuration:: How configuration of GNU packages should work.
+* Makefile Conventions:: Makefile conventions.
+* Releases:: Making releases
@end menu
@node Configuration
@section How Configuration Should Work
+@cindex program configuration
+@pindex configure
Each GNU distribution should come with a shell script named
@code{configure}. This script is given arguments which describe the
kind of machine and system you want to compile the program for.
@var{cpu}-@var{company}-@var{system}
@end example
-For example, a Sun 3 might be @samp{m68k-sun-sunos4.1}.
+For example, an Athlon-based GNU/Linux system might be
+@samp{i686-pc-linux-gnu}.
The @code{configure} script needs to be able to decode all plausible
-alternatives for how to describe a machine. Thus, @samp{sun3-sunos4.1}
-would be a valid alias. For many programs, @samp{vax-dec-ultrix} would
-be an alias for @samp{vax-dec-bsd}, simply because the differences
-between Ultrix and @sc{BSD} are rarely noticeable, but a few programs
-might need to distinguish them.
-@c Real 4.4BSD now runs on some Suns.
-
-There is a shell script called @file{config.sub} that you can use
-as a subroutine to validate system types and canonicalize aliases.
-
+alternatives for how to describe a machine. Thus,
+@samp{athlon-pc-gnu/linux} would be a valid alias. There is a shell
+script called
+@uref{http://savannah.gnu.org/@/cgi-bin/@/viewcvs/@/*checkout*/@/config/@/config/@/config.sub,
+@file{config.sub}} that you can use as a subroutine to validate system
+types and canonicalize aliases.
+
+The @code{configure} script should also take the option
+@option{--build=@var{buildtype}}, which should be equivalent to a
+plain @var{buildtype} argument. For example, @samp{configure
+--build=i686-pc-linux-gnu} is equivalent to @samp{configure
+i686-pc-linux-gnu}. When the build type is not specified by an option
+or argument, the @code{configure} script should normally guess it using
+the shell script
+@uref{http://savannah.gnu.org/@/cgi-bin/@/viewcvs/@/*checkout*/@/config/@/config/@/config.guess,
+@file{config.guess}}.
+
+@cindex optional features, configure-time
Other options are permitted to specify in more detail the software
-or hardware present on the machine, and include or exclude optional
-parts of the package:
+or hardware present on the machine, to include or exclude optional parts
+of the package, or to adjust the name of some tools or arguments to them:
@table @samp
@item --enable-@var{feature}@r{[}=@var{parameter}@r{]}
@c Giving an optional @var{parameter} of
@c @samp{no} should omit @var{package}, if it is used by default.
-Possible values of @var{package} include
+Possible values of @var{package} include
@samp{gnu-as} (or @samp{gas}), @samp{gnu-ld}, @samp{gnu-libc},
@samp{gdb},
-@samp{x},
+@samp{x},
and
@samp{x-toolkit}.
find certain files. That is outside the scope of what @samp{--with}
options are for.
-@item --nfp
-The target machine has no floating point processor.
-
-@item --gas
-The target machine assembler is GAS, the GNU assembler.
-This is obsolete; users should use @samp{--with-gnu-as} instead.
+@item @var{variable}=@var{value}
+Set the value of the variable @var{variable} to @var{value}. This is
+used to override the default values of commands or arguments in the
+build process. For example, the user could issue @samp{configure
+CFLAGS=-g CXXFLAGS=-g} to build with debugging information and without
+the default optimization.
-@item --x
-The target machine has the X Window System installed.
-This is obsolete; users should use @samp{--with-x} instead.
+Specifying variables as arguments to @code{configure}, like this:
+@example
+./configure CC=gcc
+@end example
+is preferable to setting them in environment variables:
+@example
+CC=gcc ./configure
+@end example
+as it helps to recreate the same configuration later with
+@file{config.status}.
@end table
-All @code{configure} scripts should accept all of these ``detail''
-options, whether or not they make any difference to the particular
-package at hand. In particular, they should accept any option that
-starts with @samp{--with-} or @samp{--enable-}. This is so users will
-be able to configure an entire GNU source tree at once with a single set
-of options.
+All @code{configure} scripts should accept all of the ``detail''
+options and the variable settings, whether or not they make any
+difference to the particular package at hand. In particular, they
+should accept any option that starts with @samp{--with-} or
+@samp{--enable-}. This is so users will be able to configure an
+entire GNU source tree at once with a single set of options.
You will note that the categories @samp{--with-} and @samp{--enable-}
are narrow: they @strong{do not} provide a place for any sort of option
configuration options in GNU software. We do not want GNU programs to
have idiosyncratic configuration options.
-Packages that perform part of the compilation process may support cross-compilation.
-In such a case, the host and target machines for the program may be
-different. The @code{configure} script should normally treat the
-specified type of system as both the host and the target, thus producing
-a program which works for the same type of machine that it runs on.
+Packages that perform part of the compilation process may support
+cross-compilation. In such a case, the host and target machines for the
+program may be different.
+
+The @code{configure} script should normally treat the specified type of
+system as both the host and the target, thus producing a program which
+works for the same type of machine that it runs on.
+
+To compile a program to run on a host type that differs from the build
+type, use the configure option @option{--host=@var{hosttype}}, where
+@var{hosttype} uses the same syntax as @var{buildtype}. The host type
+normally defaults to the build type.
-The way to build a cross-compiler, cross-assembler, or what have you, is
-to specify the option @samp{--host=@var{hosttype}} when running
-@code{configure}. This specifies the host system without changing the
-type of target system. The syntax for @var{hosttype} is the same as
-described above.
+To configure a cross-compiler, cross-assembler, or what have you, you
+should specify a target different from the host, using the configure
+option @samp{--target=@var{targettype}}. The syntax for
+@var{targettype} is the same as for the host type. So the command would
+look like this:
-Bootstrapping a cross-compiler requires compiling it on a machine other
-than the host it will run on. Compilation packages accept a
-configuration option @samp{--build=@var{hosttype}} for specifying the
-configuration on which you will compile them, in case that is different
-from the host.
+@example
+./configure --host=@var{hosttype} --target=@var{targettype}
+@end example
+The target type normally defaults to the host type.
Programs for which cross-operation is not meaningful need not accept the
-@samp{--host} option, because configuring an entire operating system for
-cross-operation is not a meaningful thing.
+@samp{--target} option, because configuring an entire operating system for
+cross-operation is not a meaningful operation.
Some programs have ways of configuring themselves automatically. If
your program is set up to do this, your @code{configure} script can simply
@node Releases
@section Making Releases
+@cindex packaging
+
+You should identify each release with a pair of version numbers, a
+major version and a minor. We have no objection to using more than
+two numbers, but it is very unlikely that you really need them.
Package the distribution of @code{Foo version 69.96} up in a gzipped tar
file with the name @file{foo-69.96.tar.gz}. It should unpack into a
and never changed automatically; non-source files are produced from
source files by programs under the control of the Makefile.
+@cindex @file{README} file
+The distribution should contain a file named @file{README} which gives
+the name of the package, and a general description of what it does. It
+is also good to explain the purpose of each of the first-level
+subdirectories in the package, if there are any. The @file{README} file
+should either state the version number of the package, or refer to where
+in the package it can be found.
+
+The @file{README} file should refer to the file @file{INSTALL}, which
+should contain an explanation of the installation procedure.
+
+The @file{README} file should also refer to the file which contains the
+copying conditions. The GNU GPL, if used, should be in a file called
+@file{COPYING}. If the GNU LGPL is used, it should be in a file called
+@file{COPYING.LIB}.
+
Naturally, all the source files must be in the distribution. It is okay
to include non-source files in the distribution, provided they are
up-to-date and machine-independent, so that building the distribution
Make sure that all the files in the distribution are world-readable.
-Make sure that no file name in the distribution is more than 14
-characters long. Likewise, no file created by building the program
-should have a name longer than 14 characters. The reason for this is
-that some systems adhere to a foolish interpretation of the POSIX
-standard, and refuse to open a longer name, rather than truncating as
-they did in the past.
-
Don't include any symbolic links in the distribution itself. If the tar
file contains symbolic links, then people cannot even unpack it on
systems that don't support symbolic links. Also, don't use multiple
are truncated to @file{foobarha.c} and @file{foobarha.o}, which are
distinct.
+@cindex @file{texinfo.tex}, in a distribution
Include in your distribution a copy of the @file{texinfo.tex} you used
to test print any @file{*.texinfo} or @file{*.texi} files.
the expense of possible inconvenience to a user who doesn't know what
other files to get.
-@contents
+@node References
+@chapter References to Non-Free Software and Documentation
+@cindex references to non-free material
+
+A GNU program should not recommend use of any non-free program. We
+can't stop some people from writing proprietary programs, or stop
+other people from using them, but we can and should refuse to
+advertise them to new potential customers. Proprietary software is a
+social and ethical problem, and the point of GNU is to solve that
+problem.
+
+The GNU definition of free software is found on the GNU web site at
+@url{http://www.gnu.org/philosophy/free-sw.html}, and the definition
+of free documentation is found at
+@url{http://www.gnu.org/philosophy/free-doc.html}. A list of
+important licenses and whether they qualify as free is in
+@url{http://www.gnu.org/@/licenses/@/license-list.html}. The terms
+``free'' and ``non-free'', used in this document, refer to that
+definition. If it is not clear whether a license qualifies as free
+under this definition, please ask the GNU Project by writing to
+@email{licensing@@gnu.org}. We will answer, and if the license is an
+important one, we will add it to the list.
+
+When a non-free program or system is well known, you can mention it in
+passing---that is harmless, since users who might want to use it
+probably already know about it. For instance, it is fine to explain
+how to build your package on top of some widely used non-free
+operating system, or how to use it together with some widely used
+non-free program.
+
+However, you should give only the necessary information to help those
+who already use the non-free program to use your program with
+it---don't give, or refer to, any further information about the
+proprietary program, and don't imply that the proprietary program
+enhances your program, or that its existence is in any way a good
+thing. The goal should be that people already using the proprietary
+program will get the advice they need about how to use your free
+program with it, while people who don't already use the proprietary
+program will not see anything to lead them to take an interest in it.
+
+If a non-free program or system is obscure in your program's domain,
+your program should not mention or support it at all, since doing so
+would tend to popularize the non-free program more than it popularizes
+your program. (You cannot hope to find many additional users among
+the users of Foobar if the users of Foobar are few.)
+
+Sometimes a program is free software in itself but depends on a
+non-free platform in order to run. For instance, many Java programs
+depend on the parts of Sun's Java implementation which are not yet
+free software, and won't run on the GNU Java Compiler (which does not
+yet have all the features) or won't run with the GNU Java libraries.
+We hope this particular problem will be gone in a few months, when Sun
+makes the standard Java libraries free software, but of course the
+general principle remains: you should not recommend programs that
+depend on non-free software to run.
+
+Some free programs encourage the use of non-free software. A typical
+example is @command{mplayer}. It is free software in itself, and the
+free code can handle some kinds of files. However, @command{mplayer}
+recommends use of non-free codecs for other kinds of files, and users
+that install @command{mplayer} are very likely to install those codecs
+along with it. To recommend @command{mplayer} is, in effect, to
+recommend the non-free codecs. We must not do that, so we cannot
+recommend @command{mplayer} either.
+
+In general, you should also not recommend programs that themselves
+strongly recommend the use of non-free software.
+
+A GNU package should not refer the user to any non-free documentation
+for free software. Free documentation that can be included in free
+operating systems is essential for completing the GNU system, or any
+free operating system, so it is a major focus of the GNU Project; to
+recommend use of documentation that we are not allowed to use in GNU
+would weaken the impetus for the community to produce documentation
+that we can include. So GNU packages should never recommend non-free
+documentation.
+
+By contrast, it is ok to refer to journal articles and textbooks in
+the comments of a program for explanation of how it functions, even
+though they be non-free. This is because we don't include such things
+in the GNU system even if we are allowed to---they are outside the
+scope of an operating system project.
+
+Referring to a web site that describes or recommends a non-free
+program is in effect promoting that software, so please do not make
+links (or mention by name) web sites that contain such material. This
+policy is relevant particularly for the web pages for a GNU package.
+
+Following links from nearly any web site can lead to non-free
+software; this is an inescapable aspect of the nature of the web, and
+in itself is no objection to linking to a site. As long as the site
+does not itself recommend a non-free program, there is no need be
+concerned about the sites it links to for other reasons.
+
+Thus, for example, you should not make a link to AT&T's web site,
+because that recommends AT&T's non-free software packages; you should
+not make a link to a site that links to AT&T's site saying it is a
+place to get a non-free program; but if a site you want to link to
+refers to AT&T's web site in some other context (such as long-distance
+telephone service), that is not a problem.
+
+
+@node GNU Free Documentation License
+@appendix GNU Free Documentation License
+
+@cindex FDL, GNU Free Documentation License
+@include fdl.texi
+
+@node Index
+@unnumbered Index
+@printindex cp
@bye
+
Local variables:
-update-date-leading-regexp: "@c This date is automagically updated when you save this file:\n@set lastupdate "
-update-date-trailing-regexp: ""
-eval: (load "/gd/gnuorg/update-date.el")
-eval: (add-hook 'write-file-hooks 'update-date)
+eval: (add-hook 'write-file-hooks 'time-stamp)
+time-stamp-start: "@set lastupdate "
+time-stamp-end: "$"
+time-stamp-format: "%:b %:d, %:y"
+compile-command: "make just-standards"
End:
projects / deliverable / binutils-gdb.git / blobdiff