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diff --git a/util/autoconf/standards.texi b/util/autoconf/standards.texi deleted file mode 100644 index e50b367..0000000 --- a/util/autoconf/standards.texi +++ /dev/null @@ -1,2409 +0,0 @@ -\input texinfo @c -*-texinfo-*- -@c %**start of header -@setfilename standards.info -@settitle GNU Coding Standards -@c UPDATE THIS DATE WHENEVER YOU MAKE CHANGES! -@set lastupdate 21 September 1994 -@c %**end of header - -@ifinfo -@format -START-INFO-DIR-ENTRY -* Standards: (standards). GNU coding standards. -END-INFO-DIR-ENTRY -@end format -@end ifinfo - -@setchapternewpage off - -@ifinfo -GNU Coding Standards -Copyright (C) 1992, 1993, 1994 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 - -@titlepage -@title GNU Coding Standards -@author Richard Stallman -@author last updated @value{lastupdate} -@page - -@vskip 0pt plus 1filll -Copyright @copyright{} 1992, 1993 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. -@end titlepage - -@ifinfo -@node Top, Preface, (dir), (dir) -@top Version - -Last updated @value{lastupdate}. -@end ifinfo - -@menu -* Preface:: About the GNU Coding Standards -* Reading Non-Free Code:: Referring to Proprietary Programs -* Contributions:: Accepting Contributions -* Change Logs:: Recording Changes -* Compatibility:: Compatibility with Other Implementations -* Makefile Conventions:: Makefile Conventions -* Configuration:: How Configuration Should Work -* Source Language:: Using Languages Other Than C -* Formatting:: Formatting Your Source Code -* Comments:: Commenting Your Work -* Syntactic Conventions:: Clean Use of C Constructs -* Names:: Naming Variables and Functions -* Using Extensions:: Using Non-standard Features -* System Functions:: Portability and ``standard'' library functions -* Semantics:: Program Behavior for All Programs -* Errors:: Formatting Error Messages -* Libraries:: Library Behavior -* Portability:: Portability As It Applies to GNU -* User Interfaces:: Standards for Command Line Interfaces -* Documentation:: Documenting Programs -* Releases:: Making Releases -@end menu - -@node Preface -@chapter About the GNU Coding Standards - -The GNU Coding Standards were written by Richard Stallman and other GNU -Project volunteers. Their purpose is to make the GNU system clean, -consistent, and easy to install. This document can also be read as a -guide to write portable, robust and reliable programs. It focuses on -programs written in C, but many of the rules and principles are useful -even if you write in another programming language. The rules often -state reasons for writing in a certain way. - -Corrections or suggestions regarding this document should be sent to -@code{gnu@@prep.ai.mit.edu}. 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}. - -@node Reading Non-Free Code -@chapter Referring to Proprietary Programs - -Don't in any circumstances refer to Unix source code for or during -your work on GNU! (Or to any other proprietary programs.) - -If you have a vague recollection of the internals of a Unix program, -this does not absolutely mean you can't write an imitation of it, but -do try to organize the imitation internally along different lines, -because this is likely to make the details of the Unix version -irrelevant and dissimilar to your results. - -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 -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, on the contrary, emphasize simplicity instead of speed. For some -applications, the speed of today's computers makes simpler algorithms -adequate. - -Or go for generality. For example, Unix programs often have static -tables or fixed-size strings, which make for arbitrary limits; use -dynamic allocation instead. Make sure your program handles NULs and -other funny characters in the input files. Add a programming language -for extensibility and write part of the program in that language. - -Or turn some parts of the program into independently usable libraries. -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 -@chapter 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 -enough. - -So, before adding in any contributions from other people, tell us -so we can arrange to get the papers. Then wait until we tell you -that we have received the signed papers, before you actually use the -contribution. - -This applies both before you release the program and afterward. If -you receive diffs to fix a bug, and they make significant change, we -need legal papers for it. - -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. - -I 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! - -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 -result. - -@node Change Logs -@chapter Change Logs - -Keep a change log for each directory, describing the changes made to -source files in that directory. The purpose of this is so that people -investigating bugs in the future will know about the changes that -might have introduced the bug. Often a new bug can be found by -looking at what was recently changed. More importantly, change logs -can help eliminate conceptual inconsistencies between different parts -of a program; they can give you a history of how the conflicting -concepts arose. - -Use the Emacs command @kbd{M-x add-change} to start a new entry in the -change log. An entry should have an asterisk, the name of the changed -file, and then in parentheses the name of the changed functions, -variables or whatever, followed by a colon. Then describe the changes -you made to that function or variable. - -Separate unrelated entries with blank lines. When two entries -represent parts of the same change, so that they work together, 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. - -Here are some examples: - -@example -* register.el (insert-register): Return nil. -(jump-to-register): Likewise. - -* sort.el (sort-subr): Return nil. - -* tex-mode.el (tex-bibtex-file, tex-file, tex-region): -Restart the tex shell if process is gone or stopped. -(tex-shell-running): New function. - -* expr.c (store_one_arg): Round size up for move_block_to_reg. -(expand_call): Round up when emitting USE insns. -* stmt.c (assign_parms): Round size up for move_block_from_reg. -@end example - -It's important to name the changed function or variable in full. Don't -abbreviate them; don't combine them. Subsequent maintainers will often -search for a function name to find all the change log entries that -pertain to it; if you abbreviate the name, they won't find it when they -search. For example, some people are tempted to abbreviate groups of -function names by writing @samp{* register.el -(@{insert,jump-to@}-register)}; this is not a good idea, since searching -for @code{jump-to-register} or @code{insert-register} would not find the -entry. - -There's no need to describe the full purpose of the changes or how they -work together. It is better to put such explanations in comments in the -code. That's why just ``New function'' is enough; there is a comment -with the function in the source to explain what it does. - -However, sometimes it is useful to write one line to describe the -overall purpose of a large batch of changes. - -You can think of the change log as a conceptual ``undo list'' which -explains how earlier versions were different from the current version. -People can see the current version; they don't need the change log -to tell them what is in it. What they want from a change log is a -clear explanation of how the earlier version differed. - -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. Just write in -the entry for the function being called, ``All callers changed.'' - -When you change just comments or doc strings, it is enough to write an -entry for the file, without mentioning the functions. Write just, -``Doc fix.'' There's no need to keep a change log 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. - - -@node Compatibility -@chapter Compatibility with Other Implementations - -With certain 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. - -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} 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. - -Many GNU programs suppress extensions that conflict with 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. - -When a feature is used only by users (not by programs or command -files), and it is done poorly in Unix, feel free to replace it -completely with something totally different and better. (For example, -vi is replaced with Emacs.) But it is nice to offer a compatible -feature as well. (There is a free vi clone, so we offer it.) - -Additional useful features not in Berkeley Unix are welcome. -Additional programs with no counterpart in Unix may be useful, -but our first priority is usually to duplicate what Unix already -has. - -@comment The makefile standards are in a separate file that is also -@comment included by make.texinfo. Done by roland@gnu.ai.mit.edu on 1/6/93. -@include make-stds.texi - -@node Configuration -@chapter How Configuration Should Work - -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. - -The @code{configure} script must record the configuration options so -that they affect compilation. - -One way to do this is to make a link from a standard name such as -@file{config.h} to the proper configuration file for the chosen system. -If you use this technique, the distribution should @emph{not} contain a -file named @file{config.h}. This is so that people won't be able to -build the program without configuring it first. - -Another thing that @code{configure} can do is to edit the Makefile. If -you do this, the distribution should @emph{not} contain a file named -@file{Makefile}. Instead, include a file @file{Makefile.in} which -contains the input used for editing. Once again, this is so that people -won't be able to build the program without configuring it first. - -If @code{configure} does write the @file{Makefile}, then @file{Makefile} -should have a target named @file{Makefile} which causes @code{configure} -to be rerun, setting up the same configuration that was set up last -time. The files that @code{configure} reads should be listed as -dependencies of @file{Makefile}. - -All the files which are output from the @code{configure} script should -have comments at the beginning explaining that they were generated -automatically using @code{configure}. This is so that users won't think -of trying to edit them by hand. - -The @code{configure} script should write a file named @file{config.status} -which describes which configuration options were specified when the -program was last configured. This file should be a shell script which, -if run, will recreate the same configuration. - -The @code{configure} script should accept an option of the form -@samp{--srcdir=@var{dirname}} to specify the directory where sources are found -(if it is not the current directory). This makes it possible to build -the program in a separate directory, so that the actual source directory -is not modified. - -If the user does not specify @samp{--srcdir}, then @code{configure} should -check both @file{.} and @file{..} to see if it can find the sources. If -it finds the sources in one of these places, it should use them from -there. Otherwise, it should report that it cannot find the sources, and -should exit with nonzero status. - -Usually the easy way to support @samp{--srcdir} is by editing a -definition of @code{VPATH} into the Makefile. Some rules may need to -refer explicitly to the specified source directory. To make this -possible, @code{configure} can add to the Makefile a variable named -@code{srcdir} whose value is precisely the specified directory. - -The @code{configure} script should also take an argument which specifies the -type of system to build the program for. This argument should look like -this: - -@example -@var{cpu}-@var{company}-@var{system} -@end example - -For example, a Sun 3 might be @samp{m68k-sun-sunos4.1}. - -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. So would @samp{sun3-bsd4.2}, since SunOS is -basically @sc{BSD} and no other @sc{BSD} system is used on a Sun. 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. - -There is a shell script called @file{config.sub} that you can use -as a subroutine to validate system types and canonicalize aliases. - -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: - -@table @samp -@item --enable-@var{feature}@r{[}=@var{parameter}@r{]} -Configure the package to build and install an optional user-level -facility called @var{feature}. This allows users to choose which -optional features to include. Giving an optional @var{parameter} of -@samp{no} should omit @var{feature}, if it is built by default. - -No @samp{--enable} option should @strong{ever} cause one feature to -replace another. No @samp{--enable} option should ever substitute one -useful behavior for another useful behavior. The only proper use for -@samp{--enable} is for questions of whether to build part of the program -or exclude it. - -@item --with-@var{package} -@c @r{[}=@var{parameter}@r{]} -The package @var{package} will be installed, so configure this package -to work with @var{package}. - -@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 @samp{x}, @samp{x-toolkit}, -@samp{gnu-as} (or @samp{gas}), @samp{gnu-ld}, @samp{gnu-libc}, and -@samp{gdb}. - -Do not use a @samp{--with} option to specify the file name to use to -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 --x -The target machine has the X Window System installed. -This is obsolete; users should use @samp{--with-x} instead. -@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. - -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 -you might think of. That is deliberate. We want to limit the possible -configuration options in GNU software. We do not want GNU programs to -have idiosyncratic configuration options. - -Packages that perform part of compilation 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. - -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. - -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. - -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. - -Some programs have ways of configuring themselves automatically. If -your program is set up to do this, your @code{configure} script can simply -ignore most of its arguments. - - -@node Source Language -@chapter Using Languages Other Than C - -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. So please write in C. - -There are three exceptions for this rule: - -@itemize @bullet -@item -It is okay to use a special language if the same program contains an -interpreter for that language. - -Thus, it is not a problem that GNU Emacs contains code written in Emacs -Lisp, because it comes with a Lisp interpreter. - -@item -It is okay to use another language in a tool specifically intended for -use with that language. - -This is okay 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 not of extremely widespread interest, then perhaps -it's not important if the application is inconvenient to install. -@end itemize - -@node Formatting -@chapter Formatting Your Source Code - -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. - -It is also important for function definitions to start the name of the -function in column zero. This helps people to search for function -definitions, and may also help certain tools recognize them. Thus, -the proper format is this: - -@example -static char * -concat (s1, s2) /* Name starts in column zero here */ - char *s1, *s2; -@{ /* Open brace in column zero here */ - @dots{} -@} -@end example - -@noindent -or, if you want to use @sc{ANSI} C, format the definition like this: - -@example -static char * -concat (char *s1, char *s2) -@{ - @dots{} -@} -@end example - -In @sc{ANSI} C, if the arguments don't fit nicely on one line, -split it like this: - -@example -int -lots_of_args (int an_integer, long a_long, short a_short, - double a_double, float a_float) -@dots{} -@end example - -For the body of the function, we prefer code formatted like this: - -@example -if (x < foo (y, z)) - haha = bar[4] + 5; -else - @{ - while (z) - @{ - haha += foo (z, z); - z--; - @} - return ++x + bar (); - @} -@end example - -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: - -@example -if (foo_this_is_long && bar > win (x, y, z) - && remaining_condition) -@end example - -Try to avoid having two operators of different precedence at the same -level of indentation. For example, don't write this: - -@example -mode = (inmode[j] == VOIDmode - || GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j]) - ? outmode[j] : inmode[j]); -@end example - -Instead, use extra parentheses so that the indentation shows the nesting: - -@example -mode = ((inmode[j] == VOIDmode - || (GET_MODE_SIZE (outmode[j]) > GET_MODE_SIZE (inmode[j]))) - ? outmode[j] : inmode[j]); -@end example - -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: - -@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 - -Format do-while statements like this: - -@example -do - @{ - a = foo (a); - @} -while (a > 0); -@end example - -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 -@chapter Commenting Your Work - -Every program should start with a comment saying briefly what it is for. -Example: @samp{fmt - filter for simple filling of text}. - -Please put a comment on each function saying what the function does, -what sorts of arguments it gets, and what the possible values of -arguments mean and are used for. It is not necessary to duplicate in -words the meaning of the C argument declarations, if a C type is being -used in its customary fashion. If there is anything nonstandard about -its use (such as an argument of type @code{char *} which is really the -address of the second character of a string, not the first), or any -possible values that would not work the way one would expect (such as, -that strings containing newlines are not guaranteed to work), be sure -to say so. - -Also explain the significance of the return value, if there is one. - -Please put two spaces after the end of a sentence in your comments, so -that the Emacs sentence commands will work. Also, please write -complete sentences and capitalize the first word. If a lower-case -identifer comes at the beginning of a sentence, don't capitalize it! -Changing the spelling makes it a different identifier. If you don't -like starting a sentence with a lower case letter, write the sentence -differently (e.g., ``The identifier lower-case is @dots{}''). - -The comment on a function is much clearer if you use the argument -names to speak about the argument values. The variable name itself -should be lower case, but write it in upper case when you are speaking -about the value rather than the variable itself. Thus, ``the inode -number NODE_NUM'' rather than ``an inode''. - -There is usually no purpose in restating the name of the function in -the comment before it, because the reader can see that for himself. -There might be an exception when the comment is so long that the function -itself would be off the bottom of the screen. - -There should be a comment on each static variable as well, like this: - -@example -/* Nonzero means truncate lines in the display; - zero means continue them. */ -int truncate_lines; -@end example - -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 -its sense}. @samp{#else} should have a comment describing the condition -@emph{and sense} of the code that follows. For example: - -@example -#ifdef foo - @dots{} -#else /* not foo */ - @dots{} -#endif /* not foo */ -@end example - -@noindent -but, by contrast, write the comments this way for a @samp{#ifndef}: - -@example -#ifndef foo - @dots{} -#else /* foo */ - @dots{} -#endif /* foo */ -@end example - - -@node Syntactic Conventions -@chapter Clean Use of C Constructs - -Please explicitly declare all arguments to functions. -Don't omit them just because they are @code{int}s. - -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 -(somewhere before the first function definition in the file), or else -should go in a header file. Don't put @code{extern} declarations inside -functions. - -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 -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 -declaration of each local variable into the smallest scope that includes -all its uses. This makes the program even cleaner. - -Don't use local variables or parameters that shadow global identifiers. - -Don't declare multiple variables in one declaration that spans lines. -Start a new declaration on each line, instead. For example, instead -of this: - -@example -int foo, - bar; -@end example - -@noindent -write either this: - -@example -int foo, bar; -@end example - -@noindent -or this: - -@example -int foo; -int bar; -@end example - -@noindent -(If they are global variables, each should have a comment preceding it -anyway.) - -When you have an @code{if}-@code{else} statement nested in another -@code{if} statement, always put braces around the @code{if}-@code{else}. -Thus, never write like this: - -@example -if (foo) - if (bar) - win (); - else - lose (); -@end example - -@noindent -always like this: - -@example -if (foo) - @{ - if (bar) - win (); - else - lose (); - @} -@end example - -If you have an @code{if} statement nested inside of an @code{else} -statement, either write @code{else if} on one line, like this, - -@example -if (foo) - @dots{} -else if (bar) - @dots{} -@end example - -@noindent -with its @code{then}-part indented like the preceding @code{then}-part, -or write the nested @code{if} within braces like this: - -@example -if (foo) - @dots{} -else - @{ - if (bar) - @dots{} - @} -@end example - -Don't declare both a structure tag and variables or typedefs in the -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: - -@example -if ((foo = (char *) malloc (sizeof *foo)) == 0) - fatal ("virtual memory exhausted"); -@end example - -@noindent -instead, write this: - -@example -foo = (char *) malloc (sizeof *foo); -if (foo == 0) - fatal ("virtual memory exhausted"); -@end example - -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. - -@node Names -@chapter Naming Variables and Functions - -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 -that follow a uniform convention. - -For example, you should use names like @code{ignore_space_change_flag}; -don't use names like @code{iCantReadThis}. - -Variables that indicate whether command-line options have been -specified should be named after the meaning of the option, not after -the option-letter. A comment should state both the exact meaning of -the option and its letter. For example, - -@example -/* Ignore changes in horizontal whitespace (-b). */ -int ignore_space_change_flag; -@end example - -When you want to define names with constant integer values, use -@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 System V. 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. - - -@node Using Extensions -@chapter Using Non-standard Features - -Many GNU facilities that already exist support a number of convenient -extensions over the comparable Unix facilities. Whether to use these -extensions in implementing your program is a difficult question. - -On the one hand, using the extensions can make a cleaner program. -On the other hand, people will not be able to build the program -unless the other GNU tools are available. This might cause the -program to work on fewer kinds of machines. - -With some extensions, it might be easy to provide both alternatives. -For example, you can define functions with a ``keyword'' @code{INLINE} -and define that as a macro to expand into either @code{inline} or -nothing, depending on the compiler. - -In general, perhaps it is best not to use the extensions if you can -straightforwardly do without them, but to use the extensions if they -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. - -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. - -Since most computer systems do not yet implement @sc{ANSI} C, using the -@sc{ANSI} C features is effectively using a GNU extension, so the -same considerations apply. (Except for @sc{ANSI} features that we -discourage, such as trigraphs---don't ever use them.) - - -@node System Functions -@chapter Calling System Functions - -C implementations differ substantially. ANSI C reduces but does not -eliminate the incompatibilities; meanwhile, many users wish to compile -GNU software with pre-ANSI compilers. 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 -characters written on some systems, but not on all systems. - -@item -Don't declare system functions explicitly. - -Almost any declaration for a system function is wrong on some system. -To minimize conflicts, leave it to the system header files to declare -system functions. If the headers don't declare a function, let it -remain undeclared. - -While it may seem unclean to use a function without declaring it, in -practice this works fine for most system library functions on the -systems where this really happens. The problem is only theoretical. By -contrast, actual declarations have frequently caused actual conflicts. - -@item -If you must declare a system function, don't specify the argument types. -Use an old-style declaration, not an ANSI prototype. The more you -specify about the function, the more likely a conflict. - -@item -In particular, don't unconditionally declare @code{malloc} or -@code{realloc}. - -Most GNU programs use those functions just once, in functions -conventionally named @code{xmalloc} and @code{xrealloc}. These -functions call @code{malloc} and @code{realloc}, respectively, and -check the results. - -Because @code{xmalloc} and @code{xrealloc} are defined in your program, -you can declare them in other files without any risk of type conflict. - -On most systems, @code{int} is the same length as a pointer; thus, the -calls to @code{malloc} and @code{realloc} work fine. For the few -exceptional systems (mostly 64-bit machines), you can use -@strong{conditionalized} declarations of @code{malloc} and -@code{realloc}---or put these declarations in configuration files -specific to those systems. - -@item -The string functions require special treatment. Some Unix systems have -a header file @file{string.h}; other have @file{strings.h}. Neither -file name is portable. There are two things you can do: use Autoconf to -figure out which file to include, or don't include either file. - -@item -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 ANSI -string functions are off-limits anyway because many systems still don't -support them. The string functions you can use are these: - -@example -strcpy strncpy strcat strncat -strlen strcmp strncmp -strchr strrchr -@end example - -The copy and concatenate functions work fine without a declaration as -long as you don't use their values. Using their values without a -declaration fails on systems where the width of a pointer differs from -the width of @code{int}, and perhaps in other cases. It is trivial to -avoid using their values, so do that. - -The compare functions and @code{strlen} work fine without a declaration -on most systems, possibly all the ones that GNU software runs on. -You may find it necessary to declare them @strong{conditionally} on a -few systems. - -The search functions must be declared to return @code{char *}. Luckily, -there is no variation in the data type they return. But there is -variation in their names. Some systems give these functions the names -@code{index} and @code{rindex}; other systems use the names -@code{strchr} and @code{strrchr}. Some systems support both pairs of -names, but neither pair works on all systems. - -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}.) 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 beginning of your file (or in a header) if you want to use the -names @code{strchr} and @code{strrchr} throughout: - -@example -#ifndef HAVE_STRCHR -#define strchr index -#endif -#ifndef HAVE_STRRCHR -#define strrchr rindex -#endif - -char *strchr (); -char *strrchr (); -@end example -@end itemize - -Here we assume that @code{HAVE_STRCHR} and @code{HAVE_STRRCHR} are -macros defined in systems where the corresponding functions exist. -One way to get them properly defined is to use Autoconf. - -@node Semantics -@chapter Program Behavior for All Programs - -Avoid arbitrary limits on the length or number of @emph{any} data -structure, including filenames, 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. - -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. - -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 -system call, as well as the name of the file if any and the name of the -utility. Just ``cannot open foo.c'' or ``stat failed'' is not -sufficient. - -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, -@code{realloc} may get a different block if you ask for less space. - -In Unix, @code{realloc} can destroy the storage block if it returns -zero. GNU @code{realloc} does not have this bug: if it fails, the -original block is unchanged. Feel free to assume the bug is fixed. If -you wish to run your program on Unix, and wish to avoid lossage in this -case, you can use the GNU @code{malloc}. - -You must expect @code{free} to alter the contents of the block that was -freed. Anything you want to fetch from the block, you must fetch before -calling @code{free}. - -If @code{malloc} fails in a noninteractive program, make that a fatal -error. In an interactive program (one that reads commands from the -user), it is better to abort the command and return to the command -reader loop. This allows the user to kill other processes to free up -virtual memory, and then try the command again. - -Use @code{getopt_long} to decode arguments, unless the argument syntax -makes this unreasonable. - -When static storage is to be written in during program execution, use -explicit C code to initialize it. Reserve C initialized declarations -for data that will not be changed. - -Try to avoid low-level interfaces to obscure Unix data structures (such -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. - -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. - -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 -to read the source code and run a debugger. So explain the problem with -comments in the source. The relevant data will be in variables, which -are easy to examine with the debugger, so there is no point moving them -elsewhere. - - -@node Errors -@chapter Formatting Error Messages - -Error messages from compilers should look like this: - -@example -@var{source-file-name}:@var{lineno}: @var{message} -@end example - -Error messages from other noninteractive programs should look like this: - -@example -@var{program}:@var{source-file-name}:@var{lineno}: @var{message} -@end example - -@noindent -when there is an appropriate source file, or like this: - -@example -@var{program}: @var{message} -@end example - -@noindent -when there is no relevant source file. - -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 -prompt or with the screen layout. (When the same program runs with -input from a source other than a terminal, it is not interactive and -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 filename. 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 Libraries -@chapter Library Behavior - -Try to make library functions reentrant. If they need to do dynamic -storage allocation, at least try to avoid any nonreentrancy aside from -that of @code{malloc} itself. - -Here are certain name conventions for libraries, to avoid name -conflicts. - -Choose a name prefix for the library, more than two characters long. -All external function and variable names should start with this -prefix. In addition, there should only be one of these in any given -library member. This usually means putting each one in a separate -source file. - -An exception can be made when two external symbols are always used -together, so that no reasonable program could use one without the -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. - -Static functions and variables can be used as you like and need not -fit any naming convention. - - -@node Portability -@chapter Portability As It Applies to GNU - -Much of what is called ``portability'' in the Unix world refers to -porting to different Unix versions. This is a secondary consideration -for GNU software, because its primary purpose is to run on top of one -and only one kernel, the GNU kernel, compiled with one and only one C -compiler, the GNU C compiler. The amount and kinds of variation among -GNU systems on different cpu's will be like the variation among Berkeley -4.3 systems on different cpu's. - -All users today run GNU software on non-GNU systems. So supporting a -variety of non-GNU systems is desirable; simply not paramount. -The easiest way to achieve portability to a reasonable range of systems -is to use Autoconf. It's unlikely that your program needs to know more -information about the host machine than Autoconf can provide, simply -because most of the programs that need such knowledge have already been -written. - -It is difficult to be sure exactly what facilities the GNU kernel -will provide, since it isn't finished yet. Therefore, assume you can -use anything in 4.3; just avoid using the format of semi-internal data -bases (e.g., directories) when there is a higher-level alternative -(@code{readdir}). - -You can freely assume any reasonably standard facilities in the C -language, libraries or kernel, because we will find it necessary to -support these facilities in the full GNU system, whether or not we -have already done so. The fact that there may exist kernels or C -compilers that lack these facilities is irrelevant as long as the GNU -kernel and C compiler support them. - -It remains necessary to worry about differences among cpu types, such -as the difference in byte ordering and alignment restrictions. It's -unlikely that 16-bit machines will ever be supported by GNU, so there -is no point in spending any time to consider the possibility that an -int will be less than 32 bits. - -You can assume that all pointers have the same format, regardless -of the type they point to, and that this is really an integer. -There are some weird machines where this isn't true, but they aren't -important; don't waste time catering to them. Besides, eventually -we will put function prototypes into all GNU programs, and that will -probably make your program work even on weird machines. - -Since some important machines (including the 68000) are big-endian, -it is important not to assume that the address of an @code{int} object -is also the address of its least-significant byte. Thus, don't -make the following mistake: - -@example -int c; -@dots{} -while ((c = getchar()) != EOF) - write(file_descriptor, &c, 1); -@end example - -You can assume that it is reasonable to use a meg of memory. Don't -strain to reduce memory usage unless it can get to that level. If -your program creates complicated data structures, just make them in -core and give a fatal error if malloc returns zero. - -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. - - -@node User Interfaces -@chapter Standards for Command Line Interfaces - -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. - -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. - -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 -pipe, then it is usually best to make the default behavior the one that -is useful with output to a terminal, and have an option for the other -behavior. - -Compatibility requires certain programs to depend on the type of output -device. It would be disastrous if @code{ls} or @code{sh} did not do so -in the way all users expect. In some of these cases, we supplement the -program with a preferred alternate version that does not depend on the -output device type. For example, we provide a @code{dir} program much -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 -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} -specifies; it is a GNU extension. - -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 -@code{getopt_long}. - -One of the advantages of long-named options is that they can be -consistent from program to program. For example, users should be able -to expect the ``verbose'' option of any GNU program which has one, to be -spelled precisely @samp{--verbose}. To achieve this uniformity, look at -the table of common long-option names when you choose the option names -for your program. The table appears below. - -If you use names not already in the table, please send -@samp{gnu@@prep.ai.mit.edu} a list of them, with their meanings, so we -can update the table. - -It is usually a good idea for file names given as ordinary arguments -to be input files only; any output files would be specified using -options (preferably @samp{-o}). Even if you allow an output file name -as an ordinary argument for compatibility, try to provide a suitable -option as well. This will lead to more consistency among GNU -utilities, so that there are fewer idiosyncracies for users to -remember. - -Programs should support an option @samp{--version} which prints the -program's version number on standard output and exits successfully, and -an option @samp{--help} which prints option usage information on -standard output and exits successfully. These options should inhibit -the normal function of the command; they should do nothing except print -the requested information. - -@c Please leave newlines between items in this table; it's much easier -@c to update when it isn't completely squashed together and unreadable. -@c When there is more than one short option for a long option name, put -@c a semicolon between the lists of the programs that use them, not a -@c period. --friedman - -@table @samp - -@item auto-check -@samp{-a} in @code{recode}. - -@item auto-reference -@samp{-A} in @code{ptx}. - -@item after-date -@samp{-N} in @code{tar}. - -@item all -@samp{-a} in @code{du}, @code{ls}, @code{nm}, @code{stty}, @code{uname}, -and @code{unexpand}. - -@item all-text -@samp{-a} in @code{diff}. - -@item almost-all -@samp{-A} in @code{ls}. - -@item append -@samp{-a} in @code{etags}, @code{tee}, @code{time}; -@samp{-r} in @code{tar}. - -@item archive -@samp{-a} in @code{cp}. - -@item archive-name -@samp{-n} in @code{shar}. - -@item arglength -@samp{-l} in @code{m4}. - -@item ascii -@samp{-a} in @code{diff}. - -@item assume-new -@samp{-W} in Make. - -@item assume-old -@samp{-o} in Make. - -@item backward-search -@samp{-B} in etags. - -@item basename -@samp{-f} in @code{shar}. - -@item batch -Used in GDB. - -@item baud -Used in GDB. - -@item before -@samp{-b} in @code{tac}. - -@item binary -@samp{-b} in @code{cpio} and @code{diff}. - -@item bits-per-code -@samp{-b} in @code{shar}. - -@item block-size -Used in @code{cpio} and @code{tar}. - -@item blocks -@samp{-b} in @code{head} and @code{tail}. - -@item break-file -@samp{-b} in @code{ptx}. - -@item brief -Used in various programs to make output shorter. - -@item bytes -@samp{-c} in @code{head}, @code{split}, and @code{tail}. - -@item c@t{++} -@samp{-C} in @code{etags}. - -@item catenate -@samp{-A} in @code{tar}. - -@item cd -Used in various programs to specify the directory to use. - -@item changes -@samp{-c} in @code{chgrp} and @code{chown}. - -@item classify -@samp{-F} in @code{ls}. - -@item colons -@samp{-c} in @code{recode}. - -@item command -@samp{-c} in @code{su}; -@samp{-x} in GDB. - -@item compare -@samp{-d} in @code{tar}. - -@item compress -@samp{-Z} in @code{tar} and @code{shar}. - -@item concatenate -@samp{-A} in @code{tar}. - -@item confirmation -@samp{-w} in @code{tar}. - -@item context -Used in @code{diff}. - -@item copyright -@samp{-C} in @code{ptx} and @code{recode}. - -@item core -Used in GDB. - -@item count -@samp{-q} in @code{who}. - -@item count-links -@samp{-l} in @code{du}. - -@item create -Used in @code{tar} and @code{cpio}. - -@item cut-mark -@samp{-c} in @code{shar}. - -@item cxref -@samp{-x} in @code{etags}. - -@item date -@samp{-d} in @code{touch}. - -@item debug -@samp{-d} in Make and @code{m4}; -@samp{-t} in Bison. - -@item define -@samp{-D} in @code{m4}. - -@item defines -@samp{-d} in Bison and @code{etags}. - -@item delete -@samp{-D} in @code{tar}. - -@item dereference -@samp{-L} in @code{chgrp}, @code{chown}, @code{cpio}, @code{du}, -@code{ls}, and @code{tar}. - -@item dereference-args -@samp{-D} in @code{du}. - -@item diacritics -@samp{-d} in @code{recode}. - -@item dictionary-order -@samp{-d} in @code{look}. - -@item diff -@samp{-d} in @code{tar}. - -@item digits -@samp{-n} in @code{csplit}. - -@item directory -Specify the directory to use, in various programs. In @code{ls}, it -means to show directories themselves rather than their contents. In -@code{rm} and @code{ln}, it means to not treat links to directories -specially. - -@item discard-all -@samp{-x} in @code{strip}. - -@item discard-locals -@samp{-X} in @code{strip}. - -@item diversions -@samp{-N} in @code{m4}. - -@item dry-run -@samp{-n} in Make. - -@item ed -@samp{-e} in @code{diff}. - -@item elide-empty-files -@samp{-z} in @code{csplit}. - -@item entire-new-file -@samp{-N} in @code{diff}. - -@item environment-overrides -@samp{-e} in Make. - -@item eof -@samp{-e} in @code{xargs}. - -@item epoch -Used in GDB. - -@item error-limit -Used in Makeinfo. - -@item error-output -@samp{-o} in @code{m4}. - -@item escape -@samp{-b} in @code{ls}. - -@item exclude-from -@samp{-X} in @code{tar}. - -@item exec -Used in GDB. - -@item exit -@samp{-x} in @code{xargs}. - -@item exit-0 -@samp{-e} in @code{unshar}. - -@item expand-tabs -@samp{-t} in @code{diff}. - -@item expression -@samp{-e} in @code{sed}. - -@item extern-only -@samp{-g} in @code{nm}. - -@item extract -@samp{-i} in @code{cpio}; -@samp{-x} in @code{tar}. - -@item faces -@samp{-f} in @code{finger}. - -@item fast -@samp{-f} in @code{su}. - -@item fatal-warnings -@samp{-E} in @code{m4}. - -@item file -@samp{-f} in @code{info}, Make, @code{mt}, and @code{tar}; -@samp{-n} in @code{sed}; -@samp{-r} in @code{touch}. - -@item file-prefix -@samp{-b} in Bison. - -@item file-type -@samp{-F} in @code{ls}. - -@item files-from -@samp{-T} in @code{tar}. - -@item fill-column -Used in Makeinfo. - -@item flag-truncation -@samp{-F} in @code{ptx}. - -@item fixed-output-files -@samp{-y} in Bison. - -@item follow -@samp{-f} in @code{tail}. - -@item footnote-style -Used in Makeinfo. - -@item force -@samp{-f} in @code{cp}, @code{ln}, @code{mv}, and @code{rm}. - -@item force-prefix -@samp{-F} in @code{shar}. - -@item format -Used in @code{ls}, @code{time}, and @code{ptx}. - -@item forward-search -@samp{-F} in @code{etags}. - -@item fullname -Used in GDB. - -@item gap-size -@samp{-g} in @code{ptx}. - -@item get -@samp{-x} in @code{tar}. - -@item graphic -@samp{-i} in @code{ul}. - -@item graphics -@samp{-g} in @code{recode}. - -@item group -@samp{-g} in @code{install}. - -@item gzip -@samp{-z} in @code{tar} and @code{shar}. - -@item hashsize -@samp{-H} in @code{m4}. - -@item header -@samp{-h} in @code{objdump} and @code{recode} - -@item heading -@samp{-H} in @code{who}. - -@item help -Used to ask for brief usage information. - -@item here-delimiter -@samp{-d} in @code{shar}. - -@item hide-control-chars -@samp{-q} in @code{ls}. - -@item idle -@samp{-u} in @code{who}. - -@item ifdef -@samp{-D} in @code{diff}. - -@item ignore -@samp{-I} in @code{ls}; -@samp{-x} in @code{recode}. - -@item ignore-all-space -@samp{-w} in @code{diff}. - -@item ignore-backups -@samp{-B} in @code{ls}. - -@item ignore-blank-lines -@samp{-B} in @code{diff}. - -@item ignore-case -@samp{-f} in @code{look} and @code{ptx}; -@samp{-i} in @code{diff}. - -@item ignore-errors -@samp{-i} in Make. - -@item ignore-file -@samp{-i} in @code{ptx}. - -@item ignore-indentation -@samp{-S} in @code{etags}. - -@item ignore-init-file -@samp{-f} in Oleo. - -@item ignore-interrupts -@samp{-i} in @code{tee}. - -@item ignore-matching-lines -@samp{-I} in @code{diff}. - -@item ignore-space-change -@samp{-b} in @code{diff}. - -@item ignore-zeros -@samp{-i} in @code{tar}. - -@item include -@samp{-i} in @code{etags}; -@samp{-I} in @code{m4}. - -@item include-dir -@samp{-I} in Make. - -@item incremental -@samp{-G} in @code{tar}. - -@item info -@samp{-i}, @samp{-l}, and @samp{-m} in Finger. - -@item initial -@samp{-i} in @code{expand}. - -@item initial-tab -@samp{-T} in @code{diff}. - -@item inode -@samp{-i} in @code{ls}. - -@item interactive -@samp{-i} in @code{cp}, @code{ln}, @code{mv}, @code{rm}; -@samp{-e} in @code{m4}; -@samp{-p} in @code{xargs}; -@samp{-w} in @code{tar}. - -@item intermix-type -@samp{-p} in @code{shar}. - -@item jobs -@samp{-j} in Make. - -@item just-print -@samp{-n} in Make. - -@item keep-going -@samp{-k} in Make. - -@item keep-files -@samp{-k} in @code{csplit}. - -@item kilobytes -@samp{-k} in @code{du} and @code{ls}. - -@item level-for-gzip -@samp{-g} in @code{shar}. - -@item line-bytes -@samp{-C} in @code{split}. - -@item lines -Used in @code{split}, @code{head}, and @code{tail}. - -@item link -@samp{-l} in @code{cpio}. - -@item list -@samp{-t} in @code{cpio}; -@samp{-l} in @code{recode}. - -@item list -@samp{-t} in @code{tar}. - -@item literal -@samp{-N} in @code{ls}. - -@item load-average -@samp{-l} in Make. - -@item login -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 @code{gnu@@prep.ai.mit.edu}. - -@item macro-name -@samp{-M} in @code{ptx}. - -@item mail -@samp{-m} in @code{hello} and @code{uname}. - -@item make-directories -@samp{-d} in @code{cpio}. - -@item makefile -@samp{-f} in Make. - -@item mapped -Used in GDB. - -@item max-args -@samp{-n} in @code{xargs}. - -@item max-chars -@samp{-n} in @code{xargs}. - -@item max-lines -@samp{-l} in @code{xargs}. - -@item max-load -@samp{-l} in Make. - -@item max-procs -@samp{-P} in @code{xargs}. - -@item mesg -@samp{-T} in @code{who}. - -@item message -@samp{-T} in @code{who}. - -@item minimal -@samp{-d} in @code{diff}. - -@item mixed-uuencode -@samp{-M} in @code{shar}. - -@item mode -@samp{-m} in @code{install}, @code{mkdir}, and @code{mkfifo}. - -@item modification-time -@samp{-m} in @code{tar}. - -@item multi-volume -@samp{-M} in @code{tar}. - -@item name-prefix -@samp{-a} in Bison. - -@item nesting-limit -@samp{-L} in @code{m4}. - -@item net-headers -@samp{-a} in @code{shar}. - -@item new-file -@samp{-W} in Make. - -@item no-builtin-rules -@samp{-r} in Make. - -@item no-character-count -@samp{-w} in @code{shar}. - -@item no-check-existing -@samp{-x} in @code{shar}. - -@item no-create -@samp{-c} in @code{touch}. - -@item no-defines -@samp{-D} in @code{etags}. - -@item no-dereference -@samp{-d} in @code{cp}. - -@item no-keep-going -@samp{-S} in Make. - -@item no-lines -@samp{-l} in Bison. - -@item no-piping -@samp{-P} in @code{shar}. - -@item no-prof -@samp{-e} in @code{gprof}. - -@item no-sort -@samp{-p} in @code{nm}. - -@item no-split -Used in Makeinfo. - -@item no-static -@samp{-a} in @code{gprof}. - -@item no-time -@samp{-E} in @code{gprof}. - -@item no-timestamp -@samp{-m} in @code{shar}. - -@item no-validate -Used in Makeinfo. - -@item no-verbose -@samp{-v} in @code{shar}. - -@item no-warn -Used in various programs to inhibit warnings. - -@item node -@samp{-n} in @code{info}. - -@item nodename -@samp{-n} in @code{uname}. - -@item nonmatching -@samp{-f} in @code{cpio}. - -@item nstuff -@samp{-n} in @code{objdump}. - -@item null -@samp{-0} in @code{xargs}. - -@item number -@samp{-n} in @code{cat}. - -@item number-nonblank -@samp{-b} in @code{cat}. - -@item numeric-sort -@samp{-n} in @code{nm}. - -@item numeric-uid-gid -@samp{-n} in @code{cpio} and @code{ls}. - -@item nx -Used in GDB. - -@item old-archive -@samp{-o} in @code{tar}. - -@item old-file -@samp{-o} in Make. - -@item one-file-system -@samp{-l} in @code{tar}, @code{cp}, and @code{du}. - -@item only-file -@samp{-o} in @code{ptx}. - -@item only-prof -@samp{-f} in @code{gprof}. - -@item only-time -@samp{-F} in @code{gprof}. - -@item output -In various programs, specify the output file name. - -@item output-prefix -@samp{-o} in @code{shar}. - -@item override -@samp{-o} in @code{rm}. - -@item overwrite -@samp{-c} in @code{unshar}. - -@item owner -@samp{-o} in @code{install}. - -@item paginate -@samp{-l} in @code{diff}. - -@item paragraph-indent -Used in Makeinfo. - -@item parents -@samp{-p} in @code{mkdir} and @code{rmdir}. - -@item pass-all -@samp{-p} in @code{ul}. - -@item pass-through -@samp{-p} in @code{cpio}. - -@item port -@samp{-P} in @code{finger}. - -@item portability -@samp{-c} in @code{cpio} and @code{tar}. - -@item prefix-builtins -@samp{-P} in @code{m4}. - -@item prefix -@samp{-f} in @code{csplit}. - -@item preserve -Used in @code{tar} and @code{cp}. - -@item preserve-environment -@samp{-p} in @code{su}. - -@item preserve-modification-time -@samp{-m} in @code{cpio}. - -@item preserve-order -@samp{-s} in @code{tar}. - -@item preserve-permissions -@samp{-p} in @code{tar}. - -@item print -@samp{-l} in @code{diff}. - -@item print-chars -@samp{-L} in @code{cmp}. - -@item print-data-base -@samp{-p} in Make. - -@item print-directory -@samp{-w} in Make. - -@item print-file-name -@samp{-o} in @code{nm}. - -@item print-symdefs -@samp{-s} in @code{nm}. - -@item query-user -@samp{-X} in @code{shar}. - -@item question -@samp{-q} in Make. - -@item quiet -Used in many programs to inhibit the usual output. @strong{Note:} every -program accepting @samp{--quiet} should accept @samp{--silent} as a -synonym. - -@item quote-name -@samp{-Q} in @code{ls}. - -@item rcs -@samp{-n} in @code{diff}. - -@item read-full-blocks -@samp{-B} in @code{tar}. - -@item readnow -Used in GDB. - -@item recon -@samp{-n} in Make. - -@item record-number -@samp{-R} in @code{tar}. - -@item recursive -Used in @code{chgrp}, @code{chown}, @code{cp}, @code{ls}, @code{diff}, -and @code{rm}. - -@item reference-limit -Used in Makeinfo. - -@item references -@samp{-r} in @code{ptx}. - -@item regex -@samp{-r} in @code{tac}. - -@item release -@samp{-r} in @code{uname}. - -@item relocation -@samp{-r} in @code{objdump}. - -@item rename -@samp{-r} in @code{cpio}. - -@item replace -@samp{-i} in @code{xargs}. - -@item report-identical-files -@samp{-s} in @code{diff}. - -@item reset-access-time -@samp{-a} in @code{cpio}. - -@item reverse -@samp{-r} in @code{ls} and @code{nm}. - -@item reversed-ed -@samp{-f} in @code{diff}. - -@item right-side-defs -@samp{-R} in @code{ptx}. - -@item same-order -@samp{-s} in @code{tar}. - -@item same-permissions -@samp{-p} in @code{tar}. - -@item save -@samp{-g} in @code{stty}. - -@item se -Used in GDB. - -@item sentence-regexp -@samp{-S} in @code{ptx}. - -@item separate-dirs -@samp{-S} in @code{du}. - -@item separator -@samp{-s} in @code{tac}. - -@item sequence -Used by @code{recode} to chose files or pipes for sequencing passes. - -@item shell -@samp{-s} in @code{su}. - -@item show-all -@samp{-A} in @code{cat}. - -@item show-c-function -@samp{-p} in @code{diff}. - -@item show-ends -@samp{-E} in @code{cat}. - -@item show-function-line -@samp{-F} in @code{diff}. - -@item show-tabs -@samp{-T} in @code{cat}. - -@item silent -Used in many programs to inhibit the usual output. -@strong{Note:} every program accepting -@samp{--silent} should accept @samp{--quiet} as a synonym. - -@item size -@samp{-s} in @code{ls}. - -@item sort -Used in @code{ls}. - -@item sparse -@samp{-S} in @code{tar}. - -@item speed-large-files -@samp{-H} in @code{diff}. - -@item split-at -@samp{-E} in @code{unshar}. - -@item split-size-limit -@samp{-L} in @code{shar}. - -@item squeeze-blank -@samp{-s} in @code{cat}. - -@item starting-file -Used in @code{tar} and @code{diff} to specify which file within -a directory to start processing with. - -@item stdin-file-list -@samp{-S} in @code{shar}. - -@item stop -@samp{-S} in Make. - -@item strict -@samp{-s} in @code{recode}. - -@item strip -@samp{-s} in @code{install}. - -@item strip-all -@samp{-s} in @code{strip}. - -@item strip-debug -@samp{-S} in @code{strip}. - -@item submitter -@samp{-s} in @code{shar}. - -@item suffix -@samp{-S} in @code{cp}, @code{ln}, @code{mv}. - -@item suffix-format -@samp{-b} in @code{csplit}. - -@item sum -@samp{-s} in @code{gprof}. - -@item summarize -@samp{-s} in @code{du}. - -@item symbolic -@samp{-s} in @code{ln}. - -@item symbols -Used in GDB and @code{objdump}. - -@item synclines -@samp{-s} in @code{m4}. - -@item sysname -@samp{-s} in @code{uname}. - -@item tabs -@samp{-t} in @code{expand} and @code{unexpand}. - -@item tabsize -@samp{-T} in @code{ls}. - -@item terminal -@samp{-T} in @code{tput} and @code{ul}. - -@item text -@samp{-a} in @code{diff}. - -@item text-files -@samp{-T} in @code{shar}. - -@item time -Used in @code{ls} and @code{touch}. - -@item to-stdout -@samp{-O} in @code{tar}. - -@item total -@samp{-c} in @code{du}. - -@item touch -@samp{-t} in Make, @code{ranlib}, and @code{recode}. - -@item trace -@samp{-t} in @code{m4}. - -@item traditional -@samp{-t} in @code{hello}; -@samp{-G} in @code{m4} and @code{ptx}. - -@item tty -Used in GDB. - -@item typedefs -@samp{-t} in @code{etags}. - -@item typedefs-and-c++ -@samp{-T} in @code{etags}. - -@item typeset-mode -@samp{-t} in @code{ptx}. - -@item uncompress -@samp{-z} in @code{tar}. - -@item unconditional -@samp{-u} in @code{cpio}. - -@item undefine -@samp{-U} in @code{m4}. - -@item undefined-only -@samp{-u} in @code{nm}. - -@item update -@samp{-u} in @code{cp}, @samp{etags}, @samp{mv}, @samp{tar}. - -@item uuencode -@samp{-B} in @code{shar}. - -@item vanilla-operation -@samp{-V} in @code{shar}. - -@item verbose -Print more information about progress. Many programs support this. - -@item verify -@samp{-W} in @code{tar}. - -@item version -Print the version number. - -@item version-control -@samp{-V} in @code{cp}, @code{ln}, @code{mv}. - -@item vgrind -@samp{-v} in @code{etags}. - -@item volume -@samp{-V} in @code{tar}. - -@item what-if -@samp{-W} in Make. - -@item whole-size-limit -@samp{-l} in @code{shar}. - -@item width -@samp{-w} in @code{ls} and @code{ptx}. - -@item word-regexp -@samp{-W} in @code{ptx}. - -@item writable -@samp{-T} in @code{who}. - -@item zeros -@samp{-z} in @code{gprof}. - -@end table - -@node Documentation -@chapter Documenting Programs - -Please use Texinfo for documenting GNU programs. See the Texinfo -manual, either the hardcopy or the version in the GNU Emacs Info -subsystem (@kbd{C-h i}). See existing GNU Texinfo files (e.g., those -under the @file{man/} directory in the GNU Emacs distribution) for -examples. - -The title page of the manual should state the version of the program -which the manual applies to. The Top node of the manual should also -contain this information. If the manual is changing more frequently -than or independent of the program, also state a version number for -the manual in both of these places. - -The manual should document all command-line arguments and all -commands. It should give examples of their use. But don't organize -the manual as a list of features. Instead, organize it by the -concepts a user will have before reaching that point in the manual. -Address the goals that a user will have in mind, and explain how to -accomplish them. Don't use Unix man pages as a model for how to -write GNU documentation; they are a bad example to follow. - -The manual should have a node named @samp{@var{program} Invocation} or -@samp{Invoking @var{program}}, where @var{program} stands for the name -of the program being described, as you would type it in the shell to run -the 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} containing a template for all the options and arguments -that the program uses. - -Alternatively, put a menu item in some menu whose item name fits one of -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. - -If one manual describes several programs, it should have such a node for -each program described. - -In addition to its manual, the package should have a file named -@file{NEWS} which contains a list of user-visible changes worth -mentioning. In each new release, add items to the front of the file and -identify the version they pertain to. Don't discard old items; leave -them in the file after the newer items. This way, a user upgrading from -any previous version can see what is new. - -If the @file{NEWS} file gets very long, move some of the older items -into a file named @file{ONEWS} and put a note at the end referring the -user to that file. - -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. - -It is ok to supply a man page for the program as well as a Texinfo -manual if you wish to. But keep in mind that supporting a man page -requires continual effort, each time the program is changed. Any time -you spend on the man page is time taken away from more useful things you -could contribute. - -Thus, even if a user volunteers to donate a man page, you may find this -gift costly to accept. Unless you have time on your hands, it may be -better to refuse the man page unless the same volunteer agrees to take -full responsibility for maintaining it---so that you can wash your hands -of it entirely. If the volunteer ceases to do the job, then don't feel -obliged to pick it up yourself; it may be better to withdraw the man -page until another volunteer offers to carry on with it. - -Alternatively, if you expect the discrepancies to be small enough that -the man page remains useful, put a prominent note near the beginning of -the man page explaining that you don't maintain it and that the Texinfo -manual is more authoritative, and describing how to access the Texinfo -documentation. - -@node Releases -@chapter Making Releases - -Package the distribution of Foo version 69.96 in a gzipped tar file -named @file{foo-69.96.tar.gz}. It should unpack into a subdirectory -named @file{foo-69.96}. - -Building and installing the program should never modify any of the files -contained in the distribution. This means that all the files that form -part of the program in any way must be classified into @dfn{source -files} and @dfn{non-source files}. Source files are written by humans -and never changed automatically; non-source files are produced from -source files by programs under the control of the Makefile. - -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 -normally will never modify them. We commonly include non-source files -produced by Bison, Lex, @TeX{}, and Makeinfo; this helps avoid -unnecessary dependencies between our distributions, so that users can -install whichever packages they want to install. - -Non-source files that might actually be modified by building and -installing the program should @strong{never} be included in the -distribution. So if you do distribute non-source files, always make -sure they are up to date when you make a new distribution. - -Make sure that the directory into which the distribution unpacks (as -well as any subdirectories) are all world-writable (octal mode 777). -This is so that old versions of @code{tar} which preserve the -ownership and permissions of the files from the tar archive will be -able to extract all the files even if the user is unprivileged. - -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 -names for one file in different directories, because certain file -systems cannot handle this and that prevents unpacking the -distribution. - -Try to make sure that all the file names will be unique on MS-DOG. A -name on MS-DOG consists of up to 8 characters, optionally followed by a -period and up to three characters. MS-DOG will truncate extra -characters both before and after the period. Thus, -@file{foobarhacker.c} and @file{foobarhacker.o} are not ambiguous; they -are truncated to @file{foobarha.c} and @file{foobarha.o}, which are -distinct. - -Include in your distribution a copy of the @file{texinfo.tex} you used -to test print any @file{*.texinfo} files. - -Likewise, if your program uses small GNU software packages like regex, -getopt, obstack, or termcap, include them in the distribution file. -Leaving them out would make the distribution file a little smaller at -the expense of possible inconvenience to a user who doesn't know what -other files to get. - -@contents - -@bye |