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1 \input texinfo @c -*-texinfo-*- 1 \input texinfo @c -*-texinfo-*-
2 @c %**start of header 2 @c %**start of header
3 @setfilename ../info/standards.info 3 @setfilename ../info/standards.info
4 @settitle GNU Coding Standards 4 @settitle GNU Coding Standards
5 @c This date is automagically updated when you save this file: 5 @c UPDATE THIS DATE WHENEVER YOU MAKE CHANGES!
6 @set lastupdate June 24, 1999 6 @set lastupdate 17 May 1996
7 @c %**end of header 7 @c %**end of header
8 8
9 @ifinfo 9 @ifinfo
10 @format 10 @format
11 START-INFO-DIR-ENTRY 11 START-INFO-DIR-ENTRY
26 @set CHAPTER node 26 @set CHAPTER node
27 @end ifinfo 27 @end ifinfo
28 28
29 @ifinfo 29 @ifinfo
30 GNU Coding Standards 30 GNU Coding Standards
31 Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999 Free Software Foundation, Inc. 31 Copyright (C) 1992, 1993, 1994, 1995, 1996 Free Software Foundation, Inc.
32 32
33 Permission is granted to make and distribute verbatim copies of 33 Permission is granted to make and distribute verbatim copies of
34 this manual provided the copyright notice and this permission notice 34 this manual provided the copyright notice and this permission notice
35 are preserved on all copies. 35 are preserved on all copies.
36 36
57 @author Richard Stallman 57 @author Richard Stallman
58 @author last updated @value{lastupdate} 58 @author last updated @value{lastupdate}
59 @page 59 @page
60 60
61 @vskip 0pt plus 1filll 61 @vskip 0pt plus 1filll
62 Copyright @copyright{} 1992, 1993, 1994, 1995, 1996, 1997, 1998 Free Software Foundation, Inc. 62 Copyright @copyright{} 1992, 1993, 1994, 1995, 1996 Free Software Foundation, Inc.
63 63
64 Permission is granted to make and distribute verbatim copies of 64 Permission is granted to make and distribute verbatim copies of
65 this manual provided the copyright notice and this permission notice 65 this manual provided the copyright notice and this permission notice
66 are preserved on all copies. 66 are preserved on all copies.
67 67
82 82
83 Last updated @value{lastupdate}. 83 Last updated @value{lastupdate}.
84 @end ifinfo 84 @end ifinfo
85 85
86 @menu 86 @menu
87 * Preface:: About the GNU Coding Standards 87 * Preface:: About the GNU Coding Standards
88 * Legal Issues:: Keeping Free Software Free 88 * Intellectual Property:: Keeping Free Software Free
89 * Design Advice:: General Program Design 89 * Design Advice:: General Program Design
90 * Program Behavior:: Program Behavior for All Programs 90 * Program Behavior:: Program Behavior for All Programs
91 * Writing C:: Making The Best Use of C 91 * Writing C:: Making The Best Use of C
92 * Documentation:: Documenting Programs 92 * Documentation:: Documenting Programs
93 * Managing Releases:: The Release Process 93 * Managing Releases:: The Release Process
94 * References:: References to Non-Free Software or Documentation
95 @end menu 94 @end menu
96 95
97 @node Preface 96 @node Preface
98 @chapter About the GNU Coding Standards 97 @chapter About the GNU Coding Standards
99 98
103 guide to writing portable, robust and reliable programs. It focuses on 102 guide to writing portable, robust and reliable programs. It focuses on
104 programs written in C, but many of the rules and principles are useful 103 programs written in C, but many of the rules and principles are useful
105 even if you write in another programming language. The rules often 104 even if you write in another programming language. The rules often
106 state reasons for writing in a certain way. 105 state reasons for writing in a certain way.
107 106
108 Corrections or suggestions for this document should be sent to 107 Corrections or suggestions regarding this document should be sent to
109 @email{gnu@@gnu.org}. If you make a suggestion, please include a 108 @code{gnu@@prep.ai.mit.edu}. If you make a suggestion, please include a
110 suggested new wording for it; our time is limited. We prefer a context 109 suggested new wording for it; our time is limited. We prefer a context
111 diff to the @file{standards.texi} or @file{make-stds.texi} files, but if 110 diff to the @file{standards.texi} or @file{make-stds.texi} files, but if
112 you don't have those files, please mail your suggestion anyway. 111 you don't have those files, please mail your suggestion anyway.
113 112
114 This release of the GNU Coding Standards was last updated 113 This release of the GNU Coding Standards was last updated
115 @value{lastupdate}. 114 @value{lastupdate}.
116 115
117 @node Legal Issues 116 @node Intellectual Property
118 @chapter Keeping Free Software Free 117 @chapter Keeping Free Software Free
119 118
120 This @value{CHAPTER} discusses how you can make sure that GNU software 119 This @value{CHAPTER} discusses how you can make sure that GNU software
121 remains unencumbered. 120 remains unencumbered.
122 121
123 @menu 122 @menu
124 * Reading Non-Free Code:: Referring to Proprietary Programs 123 * Reading Non-Free Code:: Referring to Proprietary Programs
125 * Contributions:: Accepting Contributions 124 * Contributions:: Accepting Contributions
126 @end menu 125 @end menu
127 126
128 @node Reading Non-Free Code 127 @node Reading Non-Free Code
129 @section Referring to Proprietary Programs 128 @section Referring to Proprietary Programs
130 129
160 159
161 160
162 @node Contributions 161 @node Contributions
163 @section Accepting Contributions 162 @section Accepting Contributions
164 163
165 If the program you are working on is copyrighted by the Free Software 164 If someone else sends you a piece of code to add to the program you are
166 Foundation, then when someone else sends you a piece of code to add to 165 working on, we need legal papers to use it---the same sort of legal
167 the program, we need legal papers to use it---just as we asked you to 166 papers we will need to get from you. @emph{Each} significant
168 sign papers initially. @emph{Each} person who makes a nontrivial 167 contributor to a program must sign some sort of legal papers in order
169 contribution to a program must sign some sort of legal papers in order 168 for us to have clear title to the program. The main author alone is not
170 for us to have clear title to the program; the main author alone is not
171 enough. 169 enough.
172 170
173 So, before adding in any contributions from other people, please tell 171 So, before adding in any contributions from other people, tell us
174 us, so we can arrange to get the papers. Then wait until we tell you 172 so we can arrange to get the papers. Then wait until we tell you
175 that we have received the signed papers, before you actually use the 173 that we have received the signed papers, before you actually use the
176 contribution. 174 contribution.
177 175
178 This applies both before you release the program and afterward. If 176 This applies both before you release the program and afterward. If
179 you receive diffs to fix a bug, and they make significant changes, we 177 you receive diffs to fix a bug, and they make significant changes, we
180 need legal papers for that change. 178 need legal papers for it.
181
182 This also applies to comments and documentation files. For copyright
183 law, comments and code are just text. Copyright applies to all kinds of
184 text, so we need legal papers for all kinds.
185
186 We know it is frustrating to ask for legal papers; it's frustrating for
187 us as well. But if you don't wait, you are going out on a limb---for
188 example, what if the contributor's employer won't sign a disclaimer?
189 You might have to take that code out again!
190 179
191 You don't need papers for changes of a few lines here or there, since 180 You don't need papers for changes of a few lines here or there, since
192 they are not significant for copyright purposes. Also, you don't need 181 they are not significant for copyright purposes. Also, you don't need
193 papers if all you get from the suggestion is some ideas, not actual code 182 papers if all you get from the suggestion is some ideas, not actual code
194 which you use. For example, if someone send you one implementation, but 183 which you use. For example, if you write a different solution to the
195 you write a different implementation of the same idea, you don't need to 184 problem, you don't need to get papers.
196 get papers. 185
186 We know this is frustrating; it's frustrating for us as well. But if
187 you don't wait, you are going out on a limb---for example, what if the
188 contributor's employer won't sign a disclaimer? You might have to take
189 that code out again!
197 190
198 The very worst thing is if you forget to tell us about the other 191 The very worst thing is if you forget to tell us about the other
199 contributor. We could be very embarrassed in court some day as a 192 contributor. We could be very embarrassed in court some day as a
200 result. 193 result.
201 194
202 We have more detailed advice for maintainers of programs; if you have
203 reached the stage of actually maintaining a program for GNU (whether
204 released or not), please ask us for a copy.
205
206 @node Design Advice 195 @node Design Advice
207 @chapter General Program Design 196 @chapter General Program Design
208 197
209 This @value{CHAPTER} discusses some of the issues you should take into 198 This @value{CHAPTER} discusses some of the issues you should take into
210 account when designing your program. 199 account when designing your program.
211 200
212 @menu 201 @menu
213 * Compatibility:: Compatibility with other implementations 202 * Compatibility:: Compatibility with other implementations
214 * Using Extensions:: Using non-standard features 203 * Using Extensions:: Using non-standard features
215 * ANSI C:: Using ANSI C features 204 * ANSI C:: Using ANSI C features
216 * Source Language:: Using languages other than C 205 * Source Language:: Using languages other than C
217 @end menu 206 @end menu
218 207
219 @node Compatibility 208 @node Compatibility
220 @section Compatibility with Other Implementations 209 @section Compatibility with Other Implementations
221 210
222 With occasional exceptions, utility programs and libraries for GNU 211 With occasional exceptions, utility programs and libraries for GNU
223 should be upward compatible with those in Berkeley Unix, and upward 212 should be upward compatible with those in Berkeley Unix, and upward
224 compatible with @sc{ansi} C if @sc{ansi} C specifies their behavior, and 213 compatible with @sc{ansi} C if @sc{ansi} C specifies their behavior, and
225 upward compatible with @sc{posix} if @sc{posix} specifies their 214 upward compatible with @sc{POSIX} if @sc{POSIX} specifies their
226 behavior. 215 behavior.
227 216
228 When these standards conflict, it is useful to offer compatibility 217 When these standards conflict, it is useful to offer compatibility
229 modes for each of them. 218 modes for each of them.
230 219
231 @sc{ansi} C and @sc{posix} prohibit many kinds of extensions. Feel free 220 @sc{ansi} C and @sc{POSIX} prohibit many kinds of extensions. Feel free
232 to make the extensions anyway, and include a @samp{--ansi}, 221 to make the extensions anyway, and include a @samp{--ansi},
233 @samp{--posix}, or @samp{--compatible} option to turn them off. 222 @samp{--posix}, or @samp{--compatible} option to turn them off.
234 However, if the extension has a significant chance of breaking any real 223 However, if the extension has a significant chance of breaking any real
235 programs or scripts, then it is not really upward compatible. Try to 224 programs or scripts, then it is not really upward compatible. Try to
236 redesign its interface. 225 redesign its interface.
237 226
238 Many GNU programs suppress extensions that conflict with @sc{posix} if the 227 Many GNU programs suppress extensions that conflict with POSIX if the
239 environment variable @code{POSIXLY_CORRECT} is defined (even if it is 228 environment variable @code{POSIXLY_CORRECT} is defined (even if it is
240 defined with a null value). Please make your program recognize this 229 defined with a null value). Please make your program recognize this
241 variable if appropriate. 230 variable if appropriate.
242 231
243 When a feature is used only by users (not by programs or command 232 When a feature is used only by users (not by programs or command
245 completely with something totally different and better. (For example, 234 completely with something totally different and better. (For example,
246 @code{vi} is replaced with Emacs.) But it is nice to offer a compatible 235 @code{vi} is replaced with Emacs.) But it is nice to offer a compatible
247 feature as well. (There is a free @code{vi} clone, so we offer it.) 236 feature as well. (There is a free @code{vi} clone, so we offer it.)
248 237
249 Additional useful features not in Berkeley Unix are welcome. 238 Additional useful features not in Berkeley Unix are welcome.
239 Additional programs with no counterpart in Unix may be useful,
240 but our first priority is usually to duplicate what Unix already
241 has.
250 242
251 @node Using Extensions 243 @node Using Extensions
252 @section Using Non-standard Features 244 @section Using Non-standard Features
253 245
254 Many GNU facilities that already exist support a number of convenient 246 Many GNU facilities that already exist support a number of convenient
288 that use @sc{ansi} C features (and therefore will not work in 280 that use @sc{ansi} C features (and therefore will not work in
289 non-@sc{ansi} compilers). And if a program is already written in 281 non-@sc{ansi} compilers). And if a program is already written in
290 @sc{ansi} C, there's no need to convert it to support non-@sc{ansi} 282 @sc{ansi} C, there's no need to convert it to support non-@sc{ansi}
291 compilers. 283 compilers.
292 284
293 If you don't know non-@sc{ansi} C, there's no need to learn it; just
294 write in @sc{ansi} C.
295
296 However, it is easy to support non-@sc{ansi} compilers in most programs, 285 However, it is easy to support non-@sc{ansi} compilers in most programs,
297 so you might still consider doing so when you write a program. And if a 286 so you might still consider doing so when you write a program. Instead
298 program you are maintaining has such support, you should try to keep it 287 of writing function definitions in @sc{ansi} prototype form,
299 working.
300
301 To support pre-@sc{ansi} C, instead of writing function definitions in
302 @sc{ansi} prototype form,
303 288
304 @example 289 @example
305 int 290 int
306 foo (int x, int y) 291 foo (int x, int y)
307 @dots{} 292 @dots{}
324 int foo (int, int); 309 int foo (int, int);
325 @end example 310 @end example
326 311
327 You need such a declaration anyway, in a header file, to get the benefit 312 You need such a declaration anyway, in a header file, to get the benefit
328 of @sc{ansi} C prototypes in all the files where the function is called. 313 of @sc{ansi} C prototypes in all the files where the function is called.
329 And once you have the declaration, you normally lose nothing by writing 314 And once you have it, you lose nothing by writing the function
330 the function definition in the pre-@sc{ansi} style. 315 definition in the pre-@sc{ansi} style.
331 316
332 This technique does not work for integer types narrower than @code{int}. 317 If you don't know non-@sc{ansi} C, there's no need to learn it; just
333 If you think of an argument as being of a type narrower than @code{int}, 318 write in @sc{ansi} C.
334 declare it as @code{int} instead.
335
336 There are a few special cases where this technique is hard to use. For
337 example, if a function argument needs to hold the system type
338 @code{dev_t}, you run into trouble, because @code{dev_t} is shorter than
339 @code{int} on some machines; but you cannot use @code{int} instead,
340 because @code{dev_t} is wider than @code{int} on some machines. There
341 is no type you can safely use on all machines in a non-@sc{ansi}
342 definition. The only way to support non-@sc{ansi} C and pass such an
343 argument is to check the width of @code{dev_t} using Autoconf and choose
344 the argument type accordingly. This may not be worth the trouble.
345 319
346 @node Source Language 320 @node Source Language
347 @section Using Languages Other Than C 321 @section Using Languages Other Than C
348 322
349 Using a language other than C is like using a non-standard feature: it 323 Using a language other than C is like using a non-standard feature: it
350 will cause trouble for users. Even if GCC supports the other language, 324 will cause trouble for users. Even if GCC supports the other language,
351 users may find it inconvenient to have to install the compiler for that 325 users may find it inconvenient to have to install the compiler for that
352 other language in order to build your program. For example, if you 326 other language in order to build your program. So please write in C.
353 write your program in C++, people will have to install the C++ compiler 327
354 in order to compile your program. Thus, it is better if you write in C. 328 There are three exceptions for this rule:
355
356 But there are three situations when there is no disadvantage in using
357 some other language:
358 329
359 @itemize @bullet 330 @itemize @bullet
360 @item 331 @item
361 It is okay to use another language if your program contains an 332 It is okay to use a special language if the same program contains an
362 interpreter for that language. 333 interpreter for that language.
363 334
364 For example, if your program links with GUILE, it is ok to write part of 335 For example, if your program links with GUILE, it is ok to write part of
365 the program in Scheme or another language supported by GUILE. 336 the program in Scheme or another language supported by GUILE.
366 337
370 341
371 This is okay because the only people who want to build the tool will be 342 This is okay because the only people who want to build the tool will be
372 those who have installed the other language anyway. 343 those who have installed the other language anyway.
373 344
374 @item 345 @item
375 If an application is of interest to a narrow community, then perhaps 346 If an application is not of extremely widespread interest, then perhaps
376 it's not important if the application is inconvenient to install. 347 it's not important if the application is inconvenient to install.
377 @end itemize 348 @end itemize
378
379 C has one other advantage over C++ and other compiled languages: more
380 people know C, so more people will find it easy to read and modify the
381 program if it is written in C.
382 349
383 @node Program Behavior 350 @node Program Behavior
384 @chapter Program Behavior for All Programs 351 @chapter Program Behavior for All Programs
385 352
386 This @value{CHAPTER} describes how to write robust software. It also 353 This @value{CHAPTER} describes how to write robust software. It also
387 describes general standards for error messages, the command line interface, 354 describes general standards for error messages, the command line interface,
388 and how libraries should behave. 355 and how libraries should behave.
389 356
390 @menu 357 @menu
391 * Semantics:: Writing robust programs 358 * Semantics:: Writing robust programs
392 * Libraries:: Library behavior 359 * Libraries:: Library behavior
393 * Errors:: Formatting error messages 360 * Errors:: Formatting error messages
394 * User Interfaces:: Standards for command line interfaces 361 * User Interfaces:: Standards for command line interfaces
395 * Option Table:: Table of long options.
396 * Memory Usage:: When and how to care about memory needs 362 * Memory Usage:: When and how to care about memory needs
397 @end menu 363 @end menu
398 364
399 @node Semantics 365 @node Semantics
400 @section Writing Robust Programs 366 @section Writing Robust Programs
403 structure, including file names, lines, files, and symbols, by allocating 369 structure, including file names, lines, files, and symbols, by allocating
404 all data structures dynamically. In most Unix utilities, ``long lines 370 all data structures dynamically. In most Unix utilities, ``long lines
405 are silently truncated''. This is not acceptable in a GNU utility. 371 are silently truncated''. This is not acceptable in a GNU utility.
406 372
407 Utilities reading files should not drop NUL characters, or any other 373 Utilities reading files should not drop NUL characters, or any other
408 nonprinting characters @emph{including those with codes above 0177}. 374 nonprinting characters @emph{including those with codes above 0177}. The
409 The only sensible exceptions would be utilities specifically intended 375 only sensible exceptions would be utilities specifically intended for
410 for interface to certain types of terminals or printers 376 interface to certain types of printers that can't handle those characters.
411 that can't handle those characters.
412 Whenever possible, try to make programs work properly with
413 sequences of bytes that represent multibyte characters, using encodings
414 such as UTF-8 and others.
415 377
416 Check every system call for an error return, unless you know you wish to 378 Check every system call for an error return, unless you know you wish to
417 ignore errors. Include the system error text (from @code{perror} or 379 ignore errors. Include the system error text (from @code{perror} or
418 equivalent) in @emph{every} error message resulting from a failing 380 equivalent) in @emph{every} error message resulting from a failing
419 system call, as well as the name of the file if any and the name of the 381 system call, as well as the name of the file if any and the name of the
451 413
452 Try to avoid low-level interfaces to obscure Unix data structures (such 414 Try to avoid low-level interfaces to obscure Unix data structures (such
453 as file directories, utmp, or the layout of kernel memory), since these 415 as file directories, utmp, or the layout of kernel memory), since these
454 are less likely to work compatibly. If you need to find all the files 416 are less likely to work compatibly. If you need to find all the files
455 in a directory, use @code{readdir} or some other high-level interface. 417 in a directory, use @code{readdir} or some other high-level interface.
456 These are supported compatibly by GNU. 418 These will be supported compatibly by GNU.
457 419
458 The preferred signal handling facilities are the BSD variant of 420 By default, the GNU system will provide the signal handling functions of
459 @code{signal}, and the @sc{posix} @code{sigaction} function; the 421 @sc{BSD} and of @sc{POSIX}. So GNU software should be written to use
460 alternative USG @code{signal} interface is an inferior design. 422 these.
461
462 Nowadays, using the @sc{posix} signal functions may be the easiest way
463 to make a program portable. If you use @code{signal}, then on GNU/Linux
464 systems running GNU libc version 1, you should include
465 @file{bsd/signal.h} instead of @file{signal.h}, so as to get BSD
466 behavior. It is up to you whether to support systems where
467 @code{signal} has only the USG behavior, or give up on them.
468 423
469 In error checks that detect ``impossible'' conditions, just abort. 424 In error checks that detect ``impossible'' conditions, just abort.
470 There is usually no point in printing any message. These checks 425 There is usually no point in printing any message. These checks
471 indicate the existence of bugs. Whoever wants to fix the bugs will have 426 indicate the existence of bugs. Whoever wants to fix the bugs will have
472 to read the source code and run a debugger. So explain the problem with 427 to read the source code and run a debugger. So explain the problem with
520 475
521 @example 476 @example
522 @var{source-file-name}:@var{lineno}: @var{message} 477 @var{source-file-name}:@var{lineno}: @var{message}
523 @end example 478 @end example
524 479
525 @noindent
526 If you want to mention the column number, use this format:
527
528 @example
529 @var{source-file-name}:@var{lineno}:@var{column}: @var{message}
530 @end example
531
532 @noindent
533 Line numbers should start from 1 at the beginning of the file, and
534 column numbers should start from 1 at the beginning of the line. (Both
535 of these conventions are chosen for compatibility.) Calculate column
536 numbers assuming that space and all ASCII printing characters have
537 equal width, and assuming tab stops every 8 columns.
538
539 Error messages from other noninteractive programs should look like this: 480 Error messages from other noninteractive programs should look like this:
540 481
541 @example 482 @example
542 @var{program}:@var{source-file-name}:@var{lineno}: @var{message} 483 @var{program}:@var{source-file-name}:@var{lineno}: @var{message}
543 @end example 484 @end example
549 @var{program}: @var{message} 490 @var{program}: @var{message}
550 @end example 491 @end example
551 492
552 @noindent 493 @noindent
553 when there is no relevant source file. 494 when there is no relevant source file.
554
555 If you want to mention the column number, use this format:
556
557 @example
558 @var{program}:@var{source-file-name}:@var{lineno}:@var{column}: @var{message}
559 @end example
560 495
561 In an interactive program (one that is reading commands from a 496 In an interactive program (one that is reading commands from a
562 terminal), it is better not to include the program name in an error 497 terminal), it is better not to include the program name in an error
563 message. The place to indicate which program is running is in the 498 message. The place to indicate which program is running is in the
564 prompt or with the screen layout. (When the same program runs with 499 prompt or with the screen layout. (When the same program runs with
583 Instead, use a run time option or a compilation switch or both 518 Instead, use a run time option or a compilation switch or both
584 to select among the alternate behaviors. 519 to select among the alternate behaviors.
585 520
586 Likewise, please don't make the behavior of the program depend on the 521 Likewise, please don't make the behavior of the program depend on the
587 type of output device it is used with. Device independence is an 522 type of output device it is used with. Device independence is an
588 important principle of the system's design; do not compromise it merely 523 important principle of the system's design; do not compromise it
589 to save someone from typing an option now and then. (Variation in error 524 merely to save someone from typing an option now and then.
590 message syntax when using a terminal is ok, because that is a side issue
591 that people do not depend on.)
592 525
593 If you think one behavior is most useful when the output is to a 526 If you think one behavior is most useful when the output is to a
594 terminal, and another is most useful when the output is a file or a 527 terminal, and another is most useful when the output is a file or a
595 pipe, then it is usually best to make the default behavior the one that 528 pipe, then it is usually best to make the default behavior the one that
596 is useful with output to a terminal, and have an option for the other 529 is useful with output to a terminal, and have an option for the other
602 program with a preferred alternate version that does not depend on the 535 program with a preferred alternate version that does not depend on the
603 output device type. For example, we provide a @code{dir} program much 536 output device type. For example, we provide a @code{dir} program much
604 like @code{ls} except that its default output format is always 537 like @code{ls} except that its default output format is always
605 multi-column format. 538 multi-column format.
606 539
607 It is a good idea to follow the @sc{posix} guidelines for the 540 It is a good idea to follow the @sc{POSIX} guidelines for the
608 command-line options of a program. The easiest way to do this is to use 541 command-line options of a program. The easiest way to do this is to use
609 @code{getopt} to parse them. Note that the GNU version of @code{getopt} 542 @code{getopt} to parse them. Note that the GNU version of @code{getopt}
610 will normally permit options anywhere among the arguments unless the 543 will normally permit options anywhere among the arguments unless the
611 special argument @samp{--} is used. This is not what @sc{posix} 544 special argument @samp{--} is used. This is not what @sc{POSIX}
612 specifies; it is a GNU extension. 545 specifies; it is a GNU extension.
613 546
614 Please define long-named options that are equivalent to the 547 Please define long-named options that are equivalent to the
615 single-letter Unix-style options. We hope to make GNU more user 548 single-letter Unix-style options. We hope to make GNU more user
616 friendly this way. This is easy to do with the GNU function 549 friendly this way. This is easy to do with the GNU function
619 One of the advantages of long-named options is that they can be 552 One of the advantages of long-named options is that they can be
620 consistent from program to program. For example, users should be able 553 consistent from program to program. For example, users should be able
621 to expect the ``verbose'' option of any GNU program which has one, to be 554 to expect the ``verbose'' option of any GNU program which has one, to be
622 spelled precisely @samp{--verbose}. To achieve this uniformity, look at 555 spelled precisely @samp{--verbose}. To achieve this uniformity, look at
623 the table of common long-option names when you choose the option names 556 the table of common long-option names when you choose the option names
624 for your program (@pxref{Option Table}). 557 for your program. The table appears below.
625 558
626 It is usually a good idea for file names given as ordinary arguments to 559 If you use names not already in the table, please send
627 be input files only; any output files would be specified using options 560 @samp{gnu@@prep.ai.mit.edu} a list of them, with their meanings, so we
628 (preferably @samp{-o} or @samp{--output}). Even if you allow an output 561 can update the table.
629 file name as an ordinary argument for compatibility, try to provide an 562
630 option as another way to specify it. This will lead to more consistency 563 It is usually a good idea for file names given as ordinary arguments
631 among GNU utilities, and fewer idiosyncracies for users to remember. 564 to be input files only; any output files would be specified using
632 565 options (preferably @samp{-o}). Even if you allow an output file name
633 All programs should support two standard options: @samp{--version} 566 as an ordinary argument for compatibility, try to provide a suitable
634 and @samp{--help}. 567 option as well. This will lead to more consistency among GNU
635 568 utilities, so that there are fewer idiosyncracies for users to
636 @table @code 569 remember.
637 @item --version 570
638 This option should direct the program to print information about its name, 571 Programs should support an option @samp{--version} which prints the
639 version, origin and legal status, all on standard output, and then exit 572 program's version number on standard output and exits successfully, and
640 successfully. Other options and arguments should be ignored once this 573 an option @samp{--help} which prints option usage information on
641 is seen, and the program should not perform its normal function. 574 standard output and exits successfully. These options should inhibit
642 575 the normal function of the command; they should do nothing except print
643 The first line is meant to be easy for a program to parse; the version 576 the requested information.
644 number proper starts after the last space. In addition, it contains
645 the canonical name for this program, in this format:
646
647 @example
648 GNU Emacs 19.30
649 @end example
650
651 @noindent
652 The program's name should be a constant string; @emph{don't} compute it
653 from @code{argv[0]}. The idea is to state the standard or canonical
654 name for the program, not its file name. There are other ways to find
655 out the precise file name where a command is found in @code{PATH}.
656
657 If the program is a subsidiary part of a larger package, mention the
658 package name in parentheses, like this:
659
660 @example
661 emacsserver (GNU Emacs) 19.30
662 @end example
663
664 @noindent
665 If the package has a version number which is different from this
666 program's version number, you can mention the package version number
667 just before the close-parenthesis.
668
669 If you @strong{need} to mention the version numbers of libraries which
670 are distributed separately from the package which contains this program,
671 you can do so by printing an additional line of version info for each
672 library you want to mention. Use the same format for these lines as for
673 the first line.
674
675 Please do not mention all of the libraries that the program uses ``just
676 for completeness''---that would produce a lot of unhelpful clutter.
677 Please mention library version numbers only if you find in practice that
678 they are very important to you in debugging.
679
680 The following line, after the version number line or lines, should be a
681 copyright notice. If more than one copyright notice is called for, put
682 each on a separate line.
683
684 Next should follow a brief statement that the program is free software,
685 and that users are free to copy and change it on certain conditions. If
686 the program is covered by the GNU GPL, say so here. Also mention that
687 there is no warranty, to the extent permitted by law.
688
689 It is ok to finish the output with a list of the major authors of the
690 program, as a way of giving credit.
691
692 Here's an example of output that follows these rules:
693
694 @smallexample
695 GNU Emacs 19.34.5
696 Copyright (C) 1996 Free Software Foundation, Inc.
697 GNU Emacs comes with NO WARRANTY,
698 to the extent permitted by law.
699 You may redistribute copies of GNU Emacs
700 under the terms of the GNU General Public License.
701 For more information about these matters,
702 see the files named COPYING.
703 @end smallexample
704
705 You should adapt this to your program, of course, filling in the proper
706 year, copyright holder, name of program, and the references to
707 distribution terms, and changing the rest of the wording as necessary.
708
709 This copyright notice only needs to mention the most recent year in
710 which changes were made---there's no need to list the years for previous
711 versions' changes. You don't have to mention the name of the program in
712 these notices, if that is inconvenient, since it appeared in the first
713 line.
714
715 @item --help
716 This option should output brief documentation for how to invoke the
717 program, on standard output, then exit successfully. Other options and
718 arguments should be ignored once this is seen, and the program should
719 not perform its normal function.
720
721 Near the end of the @samp{--help} option's output there should be a line
722 that says where to mail bug reports. It should have this format:
723
724 @example
725 Report bugs to @var{mailing-address}.
726 @end example
727 @end table
728
729 @node Option Table
730 @section Table of Long Options
731
732 Here is a table of long options used by GNU programs. It is surely
733 incomplete, but we aim to list all the options that a new program might
734 want to be compatible with. If you use names not already in the table,
735 please send @email{gnu@@gnu.org} a list of them, with their
736 meanings, so we can update the table.
737 577
738 @c Please leave newlines between items in this table; it's much easier 578 @c Please leave newlines between items in this table; it's much easier
739 @c to update when it isn't completely squashed together and unreadable. 579 @c to update when it isn't completely squashed together and unreadable.
740 @c When there is more than one short option for a long option name, put 580 @c When there is more than one short option for a long option name, put
741 @c a semicolon between the lists of the programs that use them, not a 581 @c a semicolon between the lists of the programs that use them, not a
742 @c period. --friedman 582 @c period. --friedman
743 583
584 Here is the table of long options used by GNU programs.
585
744 @table @samp 586 @table @samp
587
745 @item after-date 588 @item after-date
746 @samp{-N} in @code{tar}. 589 @samp{-N} in @code{tar}.
747 590
748 @item all 591 @item all
749 @samp{-a} in @code{du}, @code{ls}, @code{nm}, @code{stty}, @code{uname}, 592 @samp{-a} in @code{du}, @code{ls}, @code{nm}, @code{stty}, @code{uname},
790 @samp{-A} in @code{ptx}. 633 @samp{-A} in @code{ptx}.
791 634
792 @item avoid-wraps 635 @item avoid-wraps
793 @samp{-n} in @code{wdiff}. 636 @samp{-n} in @code{wdiff}.
794 637
795 @item background
796 For server programs, run in the background.
797
798 @item backward-search 638 @item backward-search
799 @samp{-B} in @code{ctags}. 639 @samp{-B} in @code{ctags}.
800 640
801 @item basename 641 @item basename
802 @samp{-f} in @code{shar}. 642 @samp{-f} in @code{shar}.
916 @samp{-L} in @code{chgrp}, @code{chown}, @code{cpio}, @code{du}, 756 @samp{-L} in @code{chgrp}, @code{chown}, @code{cpio}, @code{du},
917 @code{ls}, and @code{tar}. 757 @code{ls}, and @code{tar}.
918 758
919 @item dereference-args 759 @item dereference-args
920 @samp{-D} in @code{du}. 760 @samp{-D} in @code{du}.
921
922 @item device
923 Specify an I/O device (special file name).
924 761
925 @item diacritics 762 @item diacritics
926 @samp{-d} in @code{recode}. 763 @samp{-d} in @code{recode}.
927 764
928 @item dictionary-order 765 @item dictionary-order
1052 @samp{-f} in @code{cp}, @code{ln}, @code{mv}, and @code{rm}. 889 @samp{-f} in @code{cp}, @code{ln}, @code{mv}, and @code{rm}.
1053 890
1054 @item force-prefix 891 @item force-prefix
1055 @samp{-F} in @code{shar}. 892 @samp{-F} in @code{shar}.
1056 893
1057 @item foreground
1058 For server programs, run in the foreground;
1059 in other words, don't do anything special to run the server
1060 in the background.
1061
1062 @item format 894 @item format
1063 Used in @code{ls}, @code{time}, and @code{ptx}. 895 Used in @code{ls}, @code{time}, and @code{ptx}.
1064 896
1065 @item freeze-state 897 @item freeze-state
1066 @samp{-F} in @code{m4}. 898 @samp{-F} in @code{m4}.
1236 Used in @code{su}. 1068 Used in @code{su}.
1237 1069
1238 @item machine 1070 @item machine
1239 No listing of which programs already use this; 1071 No listing of which programs already use this;
1240 someone should check to 1072 someone should check to
1241 see if any actually do, and tell @email{gnu@@gnu.org}. 1073 see if any actually do and tell @code{gnu@@prep.ai.mit.edu}.
1242 1074
1243 @item macro-name 1075 @item macro-name
1244 @samp{-M} in @code{ptx}. 1076 @samp{-M} in @code{ptx}.
1245 1077
1246 @item mail 1078 @item mail
1361 @samp{-m} in @code{shar}. 1193 @samp{-m} in @code{shar}.
1362 1194
1363 @item no-validate 1195 @item no-validate
1364 Used in @code{makeinfo}. 1196 Used in @code{makeinfo}.
1365 1197
1366 @item no-wait
1367 Used in @code{emacsclient}.
1368
1369 @item no-warn 1198 @item no-warn
1370 Used in various programs to inhibit warnings. 1199 Used in various programs to inhibit warnings.
1371 1200
1372 @item node 1201 @item node
1373 @samp{-n} in @code{info}. 1202 @samp{-n} in @code{info}.
1415 @samp{-f} in @code{gprof}. 1244 @samp{-f} in @code{gprof}.
1416 1245
1417 @item only-time 1246 @item only-time
1418 @samp{-F} in @code{gprof}. 1247 @samp{-F} in @code{gprof}.
1419 1248
1420 @item options
1421 @samp{-o} in @code{getopt}, @code{fdlist}, @code{fdmount},
1422 @code{fdmountd}, and @code{fdumount}.
1423
1424 @item output 1249 @item output
1425 In various programs, specify the output file name. 1250 In various programs, specify the output file name.
1426 1251
1427 @item output-prefix 1252 @item output-prefix
1428 @samp{-o} in @code{shar}. 1253 @samp{-o} in @code{shar}.
1503 @samp{-p} in @code{wdiff}. 1328 @samp{-p} in @code{wdiff}.
1504 1329
1505 @item prompt 1330 @item prompt
1506 @samp{-p} in @code{ed}. 1331 @samp{-p} in @code{ed}.
1507 1332
1508 @item proxy
1509 Specify an HTTP proxy.
1510
1511 @item query-user 1333 @item query-user
1512 @samp{-X} in @code{shar}. 1334 @samp{-X} in @code{shar}.
1513 1335
1514 @item question 1336 @item question
1515 @samp{-q} in Make. 1337 @samp{-q} in Make.
1516 1338
1517 @item quiet 1339 @item quiet
1518 Used in many programs to inhibit the usual output. @strong{Note:} every 1340 Used in many programs to inhibit the usual output. @strong{Please
1519 program accepting @samp{--quiet} should accept @samp{--silent} as a 1341 note:} every program accepting @samp{--quiet} should accept
1520 synonym. 1342 @samp{--silent} as a synonym.
1521 1343
1522 @item quiet-unshar 1344 @item quiet-unshar
1523 @samp{-Q} in @code{shar} 1345 @samp{-Q} in @code{shar}
1524 1346
1525 @item quote-name 1347 @item quote-name
1628 @item show-tabs 1450 @item show-tabs
1629 @samp{-T} in @code{cat}. 1451 @samp{-T} in @code{cat}.
1630 1452
1631 @item silent 1453 @item silent
1632 Used in many programs to inhibit the usual output. 1454 Used in many programs to inhibit the usual output.
1633 @strong{Note:} every program accepting 1455 @strong{Please note:} every program accepting
1634 @samp{--silent} should accept @samp{--quiet} as a synonym. 1456 @samp{--silent} should accept @samp{--quiet} as a synonym.
1635 1457
1636 @item size 1458 @item size
1637 @samp{-s} in @code{ls}. 1459 @samp{-s} in @code{ls}.
1638
1639 @item socket
1640 Specify a file descriptor for a network server to use for its socket,
1641 instead of opening and binding a new socket. This provides a way to
1642 run, in a nonpriveledged process, a server that normally needs a
1643 reserved port number.
1644 1460
1645 @item sort 1461 @item sort
1646 Used in @code{ls}. 1462 Used in @code{ls}.
1647 1463
1648 @item source 1464 @item source
1737 @item text-files 1553 @item text-files
1738 @samp{-T} in @code{shar}. 1554 @samp{-T} in @code{shar}.
1739 1555
1740 @item time 1556 @item time
1741 Used in @code{ls} and @code{touch}. 1557 Used in @code{ls} and @code{touch}.
1742
1743 @item timeout
1744 Specify how long to wait before giving up on some operation.
1745 1558
1746 @item to-stdout 1559 @item to-stdout
1747 @samp{-O} in @code{tar}. 1560 @samp{-O} in @code{tar}.
1748 1561
1749 @item total 1562 @item total
1857 1670
1858 This @value{CHAPTER} provides advice on how best to use the C language 1671 This @value{CHAPTER} provides advice on how best to use the C language
1859 when writing GNU software. 1672 when writing GNU software.
1860 1673
1861 @menu 1674 @menu
1862 * Formatting:: Formatting Your Source Code 1675 * Formatting:: Formatting Your Source Code
1863 * Comments:: Commenting Your Work 1676 * Comments:: Commenting Your Work
1864 * Syntactic Conventions:: Clean Use of C Constructs 1677 * Syntactic Conventions:: Clean Use of C Constructs
1865 * Names:: Naming Variables and Functions 1678 * Names:: Naming Variables and Functions
1866 * System Portability:: Portability between different operating systems 1679 * System Portability:: Portability between different operating systems
1867 * CPU Portability:: Supporting the range of CPU types 1680 * CPU Portability:: Supporting the range of CPU types
1868 * System Functions:: Portability and ``standard'' library functions 1681 * System Functions:: Portability and ``standard'' library functions
1869 * Internationalization:: Techniques for internationalization 1682 * Internationalization:: Techniques for internationalization
1870 * Mmap:: How you can safely use @code{mmap}.
1871 @end menu 1683 @end menu
1872 1684
1873 @node Formatting 1685 @node Formatting
1874 @section Formatting Your Source Code 1686 @section Formatting Your Source Code
1875 1687
1994 @section Commenting Your Work 1806 @section Commenting Your Work
1995 1807
1996 Every program should start with a comment saying briefly what it is for. 1808 Every program should start with a comment saying briefly what it is for.
1997 Example: @samp{fmt - filter for simple filling of text}. 1809 Example: @samp{fmt - filter for simple filling of text}.
1998 1810
1999 Please write the comments in a GNU program in English, because English
2000 is the one language that nearly all programmers in all countries can
2001 read. If you do not write English well, please write comments in
2002 English as well as you can, then ask other people to help rewrite them.
2003 If you can't write comments in English, please find someone to work with
2004 you and translate your comments into English.
2005
2006 Please put a comment on each function saying what the function does, 1811 Please put a comment on each function saying what the function does,
2007 what sorts of arguments it gets, and what the possible values of 1812 what sorts of arguments it gets, and what the possible values of
2008 arguments mean and are used for. It is not necessary to duplicate in 1813 arguments mean and are used for. It is not necessary to duplicate in
2009 words the meaning of the C argument declarations, if a C type is being 1814 words the meaning of the C argument declarations, if a C type is being
2010 used in its customary fashion. If there is anything nonstandard about 1815 used in its customary fashion. If there is anything nonstandard about
2055 @dots{} 1860 @dots{}
2056 #else /* not foo */ 1861 #else /* not foo */
2057 @dots{} 1862 @dots{}
2058 #endif /* not foo */ 1863 #endif /* not foo */
2059 @end group 1864 @end group
2060 @group
2061 #ifdef foo
2062 @dots{}
2063 #endif /* foo */
2064 @end group
2065 @end example 1865 @end example
2066 1866
2067 @noindent 1867 @noindent
2068 but, by contrast, write the comments this way for a @samp{#ifndef}: 1868 but, by contrast, write the comments this way for a @samp{#ifndef}:
2069 1869
2073 @dots{} 1873 @dots{}
2074 #else /* foo */ 1874 #else /* foo */
2075 @dots{} 1875 @dots{}
2076 #endif /* foo */ 1876 #endif /* foo */
2077 @end group 1877 @end group
2078 @group 1878 @end example
2079 #ifndef foo 1879
2080 @dots{}
2081 #endif /* not foo */
2082 @end group
2083 @end example
2084 1880
2085 @node Syntactic Conventions 1881 @node Syntactic Conventions
2086 @section Clean Use of C Constructs 1882 @section Clean Use of C Constructs
2087 1883
2088 Please explicitly declare all arguments to functions. 1884 Please explicitly declare all arguments to functions.
2207 2003
2208 Don't make the program ugly to placate @code{lint}. Please don't insert any 2004 Don't make the program ugly to placate @code{lint}. Please don't insert any
2209 casts to @code{void}. Zero without a cast is perfectly fine as a null 2005 casts to @code{void}. Zero without a cast is perfectly fine as a null
2210 pointer constant, except when calling a varargs function. 2006 pointer constant, except when calling a varargs function.
2211 2007
2212 @node Names 2008 @node Names
2213 @section Naming Variables and Functions 2009 @section Naming Variables and Functions
2214
2215 The names of global variables and functions in a program serve as
2216 comments of a sort. So don't choose terse names---instead, look for
2217 names that give useful information about the meaning of the variable or
2218 function. In a GNU program, names should be English, like other
2219 comments.
2220
2221 Local variable names can be shorter, because they are used only within
2222 one context, where (presumably) comments explain their purpose.
2223
2224 Try to limit your use of abbreviations in symbol names. It is ok to
2225 make a few abbreviations, explain what they mean, and then use them
2226 frequently, but don't use lots of obscure abbreviations.
2227 2010
2228 Please use underscores to separate words in a name, so that the Emacs 2011 Please use underscores to separate words in a name, so that the Emacs
2229 word commands can be useful within them. Stick to lower case; reserve 2012 word commands can be useful within them. Stick to lower case; reserve
2230 upper case for macros and @code{enum} constants, and for name-prefixes 2013 upper case for macros and @code{enum} constants, and for name-prefixes
2231 that follow a uniform convention. 2014 that follow a uniform convention.
2248 When you want to define names with constant integer values, use 2031 When you want to define names with constant integer values, use
2249 @code{enum} rather than @samp{#define}. GDB knows about enumeration 2032 @code{enum} rather than @samp{#define}. GDB knows about enumeration
2250 constants. 2033 constants.
2251 2034
2252 Use file names of 14 characters or less, to avoid creating gratuitous 2035 Use file names of 14 characters or less, to avoid creating gratuitous
2253 problems on older System V systems. You can use the program 2036 problems on older System V systems. You can use the program @code{doschk} to test for
2254 @code{doschk} to test for this. @code{doschk} also tests for potential 2037 this. @code{doschk} also tests for potential name conflicts if the
2255 name conflicts if the files were loaded onto an MS-DOS file 2038 files were loaded onto an MS-DOS file system---something you may or may
2256 system---something you may or may not care about. 2039 not care about.
2257 2040
2258 @node System Portability 2041 @node System Portability
2259 @section Portability between System Types 2042 @section Portability between System Types
2260 2043
2261 In the Unix world, ``portability'' refers to porting to different Unix 2044 In the Unix world, ``portability'' refers to porting to different Unix
2281 2064
2282 Avoid using the format of semi-internal data bases (e.g., directories) 2065 Avoid using the format of semi-internal data bases (e.g., directories)
2283 when there is a higher-level alternative (@code{readdir}). 2066 when there is a higher-level alternative (@code{readdir}).
2284 2067
2285 As for systems that are not like Unix, such as MSDOS, Windows, the 2068 As for systems that are not like Unix, such as MSDOS, Windows, the
2286 Macintosh, VMS, and MVS, supporting them is often a lot of work. When 2069 Macintosh, VMS, and MVS, supporting them is usually so much work that it
2287 that is the case, it is better to spend your time adding features that 2070 is better if you don't.
2288 will be useful on GNU and GNU/Linux, rather than on supporting other 2071
2289 incompatible systems. 2072 The planned GNU kernel is not finished yet, but you can tell which
2073 facilities it will provide by looking at the GNU C Library Manual. The
2074 GNU kernel is based on Mach, so the features of Mach will also be
2075 available. However, if you use Mach features, you'll probably have
2076 trouble debugging your program today.
2290 2077
2291 @node CPU Portability 2078 @node CPU Portability
2292 @section Portability between @sc{cpu}s 2079 @section Portability between @sc{cpu}s
2293 2080
2294 Even GNU systems will differ because of differences among @sc{cpu} 2081 Even GNU systems will differ because of differences among @sc{cpu}
2322 that pass their arguments along to @code{printf} and friends: 2109 that pass their arguments along to @code{printf} and friends:
2323 2110
2324 @example 2111 @example
2325 error (s, a1, a2, a3) 2112 error (s, a1, a2, a3)
2326 char *s; 2113 char *s;
2327 char *a1, *a2, *a3; 2114 int a1, a2, a3;
2328 @{ 2115 @{
2329 fprintf (stderr, "error: "); 2116 fprintf (stderr, "error: ");
2330 fprintf (stderr, s, a1, a2, a3); 2117 fprintf (stderr, s, a1, a2, a3);
2331 @} 2118 @}
2332 @end example 2119 @end example
2333 2120
2334 @noindent 2121 @noindent
2335 In practice, this works on all machines, since a pointer is generally 2122 In practice, this works on all machines, and it is much simpler than any
2336 the widest possible kind of argument, and it is much simpler than any 2123 ``correct'' alternative. Be sure @emph{not} to use a prototype
2337 ``correct'' alternative. Be sure @emph{not} to use a prototype for such 2124 for such functions.
2338 functions.
2339 2125
2340 However, avoid casting pointers to integers unless you really need to. 2126 However, avoid casting pointers to integers unless you really need to.
2341 Outside of special situations, such casts greatly reduce portability, 2127 These assumptions really reduce portability, and in most programs they
2342 and in most programs they are easy to avoid. In the cases where casting 2128 are easy to avoid. In the cases where casting pointers to integers is
2343 pointers to integers is essential---such as, a Lisp interpreter which 2129 essential---such as, a Lisp interpreter which stores type information as
2344 stores type information as well as an address in one word---it is ok to 2130 well as an address in one word---it is ok to do so, but you'll have to
2345 do it, but you'll have to make explicit provisions to handle different 2131 make explicit provisions to handle different word sizes.
2346 word sizes.
2347 2132
2348 @node System Functions 2133 @node System Functions
2349 @section Calling System Functions 2134 @section Calling System Functions
2350 2135
2351 C implementations differ substantially. @sc{ansi} C reduces but does not 2136 C implementations differ substantially. @sc{ansi} C reduces but does not
2356 2141
2357 @itemize @bullet 2142 @itemize @bullet
2358 @item 2143 @item
2359 Don't use the value of @code{sprintf}. It returns the number of 2144 Don't use the value of @code{sprintf}. It returns the number of
2360 characters written on some systems, but not on all systems. 2145 characters written on some systems, but not on all systems.
2361
2362 @item
2363 @code{main} should be declared to return type @code{int}. It should
2364 terminate either by calling @code{exit} or by returning the integer
2365 status code; make sure it cannot ever return an undefined value.
2366 2146
2367 @item 2147 @item
2368 Don't declare system functions explicitly. 2148 Don't declare system functions explicitly.
2369 2149
2370 Almost any declaration for a system function is wrong on some system. 2150 Almost any declaration for a system function is wrong on some system.
2493 name} for the package. The text domain name is used to separate the 2273 name} for the package. The text domain name is used to separate the
2494 translations for this package from the translations for other packages. 2274 translations for this package from the translations for other packages.
2495 Normally, the text domain name should be the same as the name of the 2275 Normally, the text domain name should be the same as the name of the
2496 package---for example, @samp{fileutils} for the GNU file utilities. 2276 package---for example, @samp{fileutils} for the GNU file utilities.
2497 2277
2498 To enable gettext to work well, avoid writing code that makes 2278 To enable gettext to work, avoid writing code that makes assumptions
2499 assumptions about the structure of words or sentences. When you want 2279 about the structure of words. Don't construct words from parts. Here
2500 the precise text of a sentence to vary depending on the data, use two or 2280 is an example of what not to do:
2501 more alternative string constants each containing a complete sentences, 2281
2502 rather than inserting conditionalized words or phrases into a single 2282 @example
2503 sentence framework. 2283 prinf ("%d file%s processed", nfiles,
2504 2284 nfiles > 1 ? "s" : "");
2505 Here is an example of what not to do:
2506
2507 @example
2508 printf ("%d file%s processed", nfiles,
2509 nfiles != 1 ? "s" : "");
2510 @end example 2285 @end example
2511 2286
2512 @noindent 2287 @noindent
2513 The problem with that example is that it assumes that plurals are made 2288 The problem with that example is that it assumes that plurals are made
2514 by adding `s'. If you apply gettext to the format string, like this, 2289 by adding `s'. If you apply gettext to the format string, like this,
2515 2290
2516 @example 2291 @example
2517 printf (gettext ("%d file%s processed"), nfiles, 2292 prinf (gettext ("%d file%s processed"), nfiles,
2518 nfiles != 1 ? "s" : ""); 2293 nfiles > 1 ? "s" : "");
2519 @end example 2294 @end example
2520 2295
2521 @noindent 2296 @noindent
2522 the message can use different words, but it will still be forced to use 2297 the message can use different words, but it will still be forced to use
2523 `s' for the plural. Here is a better way: 2298 `s' for the plural. Here is a better way:
2524 2299
2525 @example 2300 @example
2526 printf ((nfiles != 1 ? "%d files processed" 2301 prinf ((nfiles > 1 ? "%d files processed"
2527 : "%d file processed"), 2302 : "%d file processed"),
2528 nfiles); 2303 nfiles);
2529 @end example 2304 @end example
2530 2305
2531 @noindent 2306 @noindent
2532 This way, you can apply gettext to each of the two strings 2307 This way, you can apply gettext to each of the two strings
2533 independently: 2308 independently:
2534 2309
2535 @example 2310 @example
2536 printf ((nfiles != 1 ? gettext ("%d files processed") 2311 prinf ((nfiles > 1 ? gettext ("%d files processed")
2537 : gettext ("%d file processed")), 2312 : gettext ("%d file processed")),
2538 nfiles); 2313 nfiles);
2539 @end example 2314 @end example
2540 2315
2541 @noindent 2316 @noindent
2542 This can be any method of forming the plural of the word for ``file'', and 2317 This can handle any language, no matter how it forms the plural of the
2543 also handles languages that require agreement in the word for 2318 word for ``file.''
2544 ``processed''.
2545
2546 A similar problem appears at the level of sentence structure with this
2547 code:
2548
2549 @example
2550 printf ("# Implicit rule search has%s been done.\n",
2551 f->tried_implicit ? "" : " not");
2552 @end example
2553
2554 @noindent
2555 Adding @code{gettext} calls to this code cannot give correct results for
2556 all languages, because negation in some languages requires adding words
2557 at more than one place in the sentence. By contrast, adding
2558 @code{gettext} calls does the job straightfowardly if the code starts
2559 out like this:
2560
2561 @example
2562 printf (f->tried_implicit
2563 ? "# Implicit rule search has been done.\n",
2564 : "# Implicit rule search has not been done.\n");
2565 @end example
2566
2567 @node Mmap
2568 @section Mmap
2569
2570 Don't assume that @code{mmap} either works on all files or fails
2571 for all files. It may work on some files and fail on others.
2572
2573 The proper way to use @code{mmap} is to try it on the specific file for
2574 which you want to use it---and if @code{mmap} doesn't work, fall back on
2575 doing the job in another way using @code{read} and @code{write}.
2576
2577 The reason this precaution is needed is that the GNU kernel (the HURD)
2578 provides a user-extensible file system, in which there can be many
2579 different kinds of ``ordinary files.'' Many of them support
2580 @code{mmap}, but some do not. It is important to make programs handle
2581 all these kinds of files.
2582 2319
2583 @node Documentation 2320 @node Documentation
2584 @chapter Documenting Programs 2321 @chapter Documenting Programs
2585 2322
2586 @menu 2323 @menu
2587 * GNU Manuals:: Writing proper manuals. 2324 * GNU Manuals:: Writing proper manuals.
2588 * Manual Structure Details:: Specific structure conventions. 2325 * Manual Structure Details:: Specific structure conventions.
2589 * License for Manuals:: Writing the distribution terms for a manual.
2590 * NEWS File:: NEWS files supplement manuals. 2326 * NEWS File:: NEWS files supplement manuals.
2591 * Change Logs:: Recording Changes 2327 * Change Logs:: Recording Changes
2592 * Man Pages:: Man pages are secondary. 2328 * Man Pages:: Man pages are secondary.
2593 * Reading other Manuals:: How far you can go in learning 2329 * Reading other Manuals:: How far you can go in learning
2594 from other manuals. 2330 from other manuals.
2595 @end menu 2331 @end menu
2596 2332
2597 @node GNU Manuals 2333 @node GNU Manuals
2598 @section GNU Manuals 2334 @section GNU Manuals
2599 2335
2600 The preferred way to document part of the GNU system is to write a 2336 The preferred way to document part of the GNU system is to write a
2601 manual in the Texinfo formatting language. This makes it possible to 2337 manual in the Texinfo formatting language. See the Texinfo manual,
2602 produce a good quality formatted book, using @TeX{}, and to generate an 2338 either the hardcopy, or the on-line version available through
2603 Info file. It is also possible to generate HTML output from Texinfo 2339 @code{info} or the Emacs Info subsystem (@kbd{C-h i}).
2604 source. See the Texinfo manual, either the hardcopy, or the on-line 2340
2605 version available through @code{info} or the Emacs Info subsystem 2341 The manual should document all of the program's command-line options and
2606 (@kbd{C-h i}). 2342 all of its commands. It should give examples of their use. But don't
2607 2343 organize the manual as a list of features. Instead, organize it
2608 Programmers often find it most natural to structure the documentation 2344 logically, by subtopics. Address the goals that a user will have in
2609 following the structure of the implementation, which they know. But 2345 mind, and explain how to accomplish them.
2610 this structure is not necessarily good for explaining how to use the
2611 program; it may be irrelevant and confusing for a user.
2612
2613 At every level, from the sentences in a paragraph to the grouping of
2614 topics into separate manuals, the right way to structure documentation
2615 is according to the concepts and questions that a user will have in mind
2616 when reading it. Sometimes this structure of ideas matches the
2617 structure of the implementation of the software being documented---but
2618 often they are different. Often the most important part of learning to
2619 write good documentation is learning to notice when you are structuring
2620 the documentation like the implementation, and think about better
2621 alternatives.
2622
2623 For example, each program in the GNU system probably ought to be
2624 documented in one manual; but this does not mean each program should
2625 have its own manual. That would be following the structure of the
2626 implementation, rather than the structure that helps the user
2627 understand.
2628
2629 Instead, each manual should cover a coherent @emph{topic}. For example,
2630 instead of a manual for @code{diff} and a manual for @code{diff3}, we
2631 have one manual for ``comparison of files'' which covers both of those
2632 programs, as well as @code{cmp}. By documenting these programs
2633 together, we can make the whole subject clearer.
2634
2635 The manual which discusses a program should document all of the
2636 program's command-line options and all of its commands. It should give
2637 examples of their use. But don't organize the manual as a list of
2638 features. Instead, organize it logically, by subtopics. Address the
2639 questions that a user will ask when thinking about the job that the
2640 program does.
2641 2346
2642 In general, a GNU manual should serve both as tutorial and reference. 2347 In general, a GNU manual should serve both as tutorial and reference.
2643 It should be set up for convenient access to each topic through Info, 2348 It should be set up for convenient access to each topic through Info,
2644 and for reading straight through (appendixes aside). A GNU manual 2349 and for reading straight through (appendixes aside). A GNU manual
2645 should give a good introduction to a beginner reading through from the 2350 should give a good introduction to a beginner reading through from the
2646 start, and should also provide all the details that hackers want. 2351 start, and should also provide all the details that hackers want.
2647 The Bison manual is a good example of this---please take a look at it
2648 to see what we mean.
2649 2352
2650 That is not as hard as it first sounds. Arrange each chapter as a 2353 That is not as hard as it first sounds. Arrange each chapter as a
2651 logical breakdown of its topic, but order the sections, and write their 2354 logical breakdown of its topic, but order the sections, and write their
2652 text, so that reading the chapter straight through makes sense. Do 2355 text, so that reading the chapter straight through makes sense. Do
2653 likewise when structuring the book into chapters, and when structuring a 2356 likewise when structuring the book into chapters, and when structuring a
2658 are purely tutorial and cover the basics of the subject. These provide 2361 are purely tutorial and cover the basics of the subject. These provide
2659 the framework for a beginner to understand the rest of the manual. The 2362 the framework for a beginner to understand the rest of the manual. The
2660 Bison manual provides a good example of how to do this. 2363 Bison manual provides a good example of how to do this.
2661 2364
2662 Don't use Unix man pages as a model for how to write GNU documentation; 2365 Don't use Unix man pages as a model for how to write GNU documentation;
2663 most of them are terse, badly structured, and give inadequate 2366 they are a bad example to follow.
2664 explanation of the underlying concepts. (There are, of course
2665 exceptions.) Also Unix man pages use a particular format which is
2666 different from what we use in GNU manuals.
2667
2668 Please include an email address in the manual for where to report
2669 bugs @emph{in the manual}.
2670 2367
2671 Please do not use the term ``pathname'' that is used in Unix 2368 Please do not use the term ``pathname'' that is used in Unix
2672 documentation; use ``file name'' (two words) instead. We use the term 2369 documentation; use ``file name'' (two words) instead. We use the term
2673 ``path'' only for search paths, which are lists of directory names. 2370 ``path'' only for search paths, which are lists of file names.
2674
2675 Please do not use the term ``illegal'' to refer to erroneous input to a
2676 computer program. Please use ``invalid'' for this, and reserve the term
2677 ``illegal'' for violations of law.
2678 2371
2679 @node Manual Structure Details 2372 @node Manual Structure Details
2680 @section Manual Structure Details 2373 @section Manual Structure Details
2681 2374
2682 The title page of the manual should state the version of the programs or 2375 The title page of the manual should state the version of the program
2683 packages documented in the manual. The Top node of the manual should 2376 to which the manual applies. The Top node of the manual should also
2684 also contain this information. If the manual is changing more 2377 contain this information. If the manual is changing more frequently
2685 frequently than or independent of the program, also state a version 2378 than or independent of the program, also state a version number for
2686 number for the manual in both of these places. 2379 the manual in both of these places.
2687 2380
2688 Each program documented in the manual should have a node named 2381 The manual should have a node named @samp{@var{program} Invocation} or
2689 @samp{@var{program} Invocation} or @samp{Invoking @var{program}}. This 2382 @samp{Invoking @var{program}}, where @var{program} stands for the name
2690 node (together with its subnodes, if any) should describe the program's 2383 of the program being described, as you would type it in the shell to run
2691 command line arguments and how to run it (the sort of information people 2384 the program. This node (together with its subnodes, if any) should
2692 would look in a man page for). Start with an @samp{@@example} 2385 describe the program's command line arguments and how to run it (the
2693 containing a template for all the options and arguments that the program 2386 sort of information people would look in a man page for). Start with an
2694 uses. 2387 @samp{@@example} containing a template for all the options and arguments
2388 that the program uses.
2695 2389
2696 Alternatively, put a menu item in some menu whose item name fits one of 2390 Alternatively, put a menu item in some menu whose item name fits one of
2697 the above patterns. This identifies the node which that item points to 2391 the above patterns. This identifies the node which that item points to
2698 as the node for this purpose, regardless of the node's actual name. 2392 as the node for this purpose, regardless of the node's actual name.
2699 2393
2700 There will be automatic features for specifying a program name and 2394 There will be automatic features for specifying a program name and
2701 quickly reading just this part of its manual. 2395 quickly reading just this part of its manual.
2702 2396
2703 If one manual describes several programs, it should have such a node for 2397 If one manual describes several programs, it should have such a node for
2704 each program described. 2398 each program described.
2705
2706 @node License for Manuals
2707 @section License for Manuals
2708
2709 If the manual contains a copy of the GNU GPL or GNU LGPL, or if it
2710 contains chapters that make political or personal statements, please
2711 copy the distribution terms of the GNU Emacs Manual, and adapt it by
2712 modifying appropriately the list of special chapters that may not be
2713 modified or deleted.
2714
2715 If the manual does not contain any such chapters, then imitate the
2716 simpler distribution terms of the Texinfo manual.
2717 2399
2718 @node NEWS File 2400 @node NEWS File
2719 @section The NEWS File 2401 @section The NEWS File
2720 2402
2721 In addition to its manual, the package should have a file named 2403 In addition to its manual, the package should have a file named
2734 2416
2735 Keep a change log to describe all the changes made to program source 2417 Keep a change log to describe all the changes made to program source
2736 files. The purpose of this is so that people investigating bugs in the 2418 files. The purpose of this is so that people investigating bugs in the
2737 future will know about the changes that might have introduced the bug. 2419 future will know about the changes that might have introduced the bug.
2738 Often a new bug can be found by looking at what was recently changed. 2420 Often a new bug can be found by looking at what was recently changed.
2739 More importantly, change logs can help you eliminate conceptual 2421 More importantly, change logs can help eliminate conceptual
2740 inconsistencies between different parts of a program, by giving you a 2422 inconsistencies between different parts of a program; they can give you
2741 history of how the conflicting concepts arose and who they came from. 2423 a history of how the conflicting concepts arose.
2742 2424
2743 @menu 2425 A change log file is normally called @file{ChangeLog} and covers an
2744 * Change Log Concepts:: 2426 entire directory. Each directory can have its own change log, or a
2745 * Style of Change Logs:: 2427 directory can use the change log of its parent directory--it's up to
2746 * Simple Changes:: 2428 you.
2747 * Conditional Changes:: 2429
2748 @end menu 2430 Another alternative is to record change log information with a version
2749 2431 control system such as RCS or CVS. This can be converted automatically
2750 @node Change Log Concepts 2432 to a @file{ChangeLog} file.
2751 @subsection Change Log Concepts 2433
2434 The easiest way to add an entry to @file{ChangeLog} is with the Emacs
2435 command @kbd{M-x add-change-log-entry}. An entry should have an
2436 asterisk, the name of the changed file, and then in parentheses the name
2437 of the changed functions, variables or whatever, followed by a colon.
2438 Then describe the changes you made to that function or variable.
2439
2440 Separate unrelated entries with blank lines. When two entries
2441 represent parts of the same change, so that they work together, then
2442 don't put blank lines between them. Then you can omit the file name
2443 and the asterisk when successive entries are in the same file.
2444
2445 Here are some examples:
2446
2447 @example
2448 * register.el (insert-register): Return nil.
2449 (jump-to-register): Likewise.
2450
2451 * sort.el (sort-subr): Return nil.
2452
2453 * tex-mode.el (tex-bibtex-file, tex-file, tex-region):
2454 Restart the tex shell if process is gone or stopped.
2455 (tex-shell-running): New function.
2456
2457 * expr.c (store_one_arg): Round size up for move_block_to_reg.
2458 (expand_call): Round up when emitting USE insns.
2459 * stmt.c (assign_parms): Round size up for move_block_from_reg.
2460 @end example
2461
2462 It's important to name the changed function or variable in full. Don't
2463 abbreviate function or variable names, and don't combine them.
2464 Subsequent maintainers will often
2465 search for a function name to find all the change log entries that
2466 pertain to it; if you abbreviate the name, they won't find it when they
2467 search. For example, some people are tempted to abbreviate groups of
2468 function names by writing @samp{* register.el
2469 (@{insert,jump-to@}-register)}; this is not a good idea, since searching
2470 for @code{jump-to-register} or @code{insert-register} would not find the
2471 entry.
2472
2473 There's no need to describe the full purpose of the changes or how they
2474 work together. It is better to put such explanations in comments in the
2475 code. That's why just ``New function'' is enough; there is a comment
2476 with the function in the source to explain what it does.
2477
2478 However, sometimes it is useful to write one line to describe the
2479 overall purpose of a large batch of changes.
2752 2480
2753 You can think of the change log as a conceptual ``undo list'' which 2481 You can think of the change log as a conceptual ``undo list'' which
2754 explains how earlier versions were different from the current version. 2482 explains how earlier versions were different from the current version.
2755 People can see the current version; they don't need the change log 2483 People can see the current version; they don't need the change log
2756 to tell them what is in it. What they want from a change log is a 2484 to tell them what is in it. What they want from a change log is a
2757 clear explanation of how the earlier version differed. 2485 clear explanation of how the earlier version differed.
2758 2486
2759 The change log file is normally called @file{ChangeLog} and covers an 2487 When you change the calling sequence of a function in a simple
2760 entire directory. Each directory can have its own change log, or a 2488 fashion, and you change all the callers of the function, there is no
2761 directory can use the change log of its parent directory--it's up to 2489 need to make individual entries for all the callers. Just write in
2762 you.
2763
2764 Another alternative is to record change log information with a version
2765 control system such as RCS or CVS. This can be converted automatically
2766 to a @file{ChangeLog} file using @code{rcs2log}; in Emacs, the command
2767 @kbd{C-x v a} (@code{vc-update-change-log}) does the job.
2768
2769 There's no need to describe the full purpose of the changes or how they
2770 work together. If you think that a change calls for explanation, you're
2771 probably right. Please do explain it---but please put the explanation
2772 in comments in the code, where people will see it whenever they see the
2773 code. For example, ``New function'' is enough for the change log when
2774 you add a function, because there should be a comment before the
2775 function definition to explain what it does.
2776
2777 However, sometimes it is useful to write one line to describe the
2778 overall purpose of a batch of changes.
2779
2780 The easiest way to add an entry to @file{ChangeLog} is with the Emacs
2781 command @kbd{M-x add-change-log-entry}. An entry should have an
2782 asterisk, the name of the changed file, and then in parentheses the name
2783 of the changed functions, variables or whatever, followed by a colon.
2784 Then describe the changes you made to that function or variable.
2785
2786 @node Style of Change Logs
2787 @subsection Style of Change Logs
2788
2789 Here are some examples of change log entries:
2790
2791 @example
2792 * register.el (insert-register): Return nil.
2793 (jump-to-register): Likewise.
2794
2795 * sort.el (sort-subr): Return nil.
2796
2797 * tex-mode.el (tex-bibtex-file, tex-file, tex-region):
2798 Restart the tex shell if process is gone or stopped.
2799 (tex-shell-running): New function.
2800
2801 * expr.c (store_one_arg): Round size up for move_block_to_reg.
2802 (expand_call): Round up when emitting USE insns.
2803 * stmt.c (assign_parms): Round size up for move_block_from_reg.
2804 @end example
2805
2806 It's important to name the changed function or variable in full. Don't
2807 abbreviate function or variable names, and don't combine them.
2808 Subsequent maintainers will often search for a function name to find all
2809 the change log entries that pertain to it; if you abbreviate the name,
2810 they won't find it when they search.
2811
2812 For example, some people are tempted to abbreviate groups of function
2813 names by writing @samp{* register.el (@{insert,jump-to@}-register)};
2814 this is not a good idea, since searching for @code{jump-to-register} or
2815 @code{insert-register} would not find that entry.
2816
2817 Separate unrelated change log entries with blank lines. When two
2818 entries represent parts of the same change, so that they work together,
2819 then don't put blank lines between them. Then you can omit the file
2820 name and the asterisk when successive entries are in the same file.
2821
2822 @node Simple Changes
2823 @subsection Simple Changes
2824
2825 Certain simple kinds of changes don't need much detail in the change
2826 log.
2827
2828 When you change the calling sequence of a function in a simple fashion,
2829 and you change all the callers of the function, there is no need to make
2830 individual entries for all the callers that you changed. Just write in
2831 the entry for the function being called, ``All callers changed.'' 2490 the entry for the function being called, ``All callers changed.''
2832 2491
2833 @example
2834 * keyboard.c (Fcommand_execute): New arg SPECIAL.
2835 All callers changed.
2836 @end example
2837
2838 When you change just comments or doc strings, it is enough to write an 2492 When you change just comments or doc strings, it is enough to write an
2839 entry for the file, without mentioning the functions. Just ``Doc 2493 entry for the file, without mentioning the functions. Write just,
2840 fixes'' is enough for the change log. 2494 ``Doc fix.''
2841 2495
2842 There's no need to make change log entries for documentation files. 2496 There's no need to make change log entries for documentation files.
2843 This is because documentation is not susceptible to bugs that are hard 2497 This is because documentation is not susceptible to bugs that are hard
2844 to fix. Documentation does not consist of parts that must interact in a 2498 to fix. Documentation does not consist of parts that must interact in a
2845 precisely engineered fashion. To correct an error, you need not know 2499 precisely engineered fashion. To correct an error, you need not know
2846 the history of the erroneous passage; it is enough to compare what the 2500 the history of the erroneous passage; it is enough to compare the
2847 documentation says with the way the program actually works. 2501 passage with the way the program actually works.
2848
2849 @node Conditional Changes
2850 @subsection Conditional Changes
2851
2852 C programs often contain compile-time @code{#if} conditionals. Many
2853 changes are conditional; sometimes you add a new definition which is
2854 entirely contained in a conditional. It is very useful to indicate in
2855 the change log the conditions for which the change applies.
2856
2857 Our convention for indicating conditional changes is to use square
2858 brackets around the name of the condition.
2859
2860 Here is a simple example, describing a change which is conditional but
2861 does not have a function or entity name associated with it:
2862
2863 @example
2864 * xterm.c [SOLARIS2]: Include string.h.
2865 @end example
2866
2867 Here is an entry describing a new definition which is entirely
2868 conditional. This new definition for the macro @code{FRAME_WINDOW_P} is
2869 used only when @code{HAVE_X_WINDOWS} is defined:
2870
2871 @example
2872 * frame.h [HAVE_X_WINDOWS] (FRAME_WINDOW_P): Macro defined.
2873 @end example
2874
2875 Here is an entry for a change within the function @code{init_display},
2876 whose definition as a whole is unconditional, but the changes themselves
2877 are contained in a @samp{#ifdef HAVE_LIBNCURSES} conditional:
2878
2879 @example
2880 * dispnew.c (init_display) [HAVE_LIBNCURSES]: If X, call tgetent.
2881 @end example
2882
2883 Here is an entry for a change that takes affect only when
2884 a certain macro is @emph{not} defined:
2885
2886 @example
2887 (gethostname) [!HAVE_SOCKETS]: Replace with winsock version.
2888 @end example
2889 2502
2890 @node Man Pages 2503 @node Man Pages
2891 @section Man Pages 2504 @section Man Pages
2892 2505
2893 In the GNU project, man pages are secondary. It is not necessary or 2506 In the GNU project, man pages are secondary. It is not necessary or
2943 layout should also conform to the standards discussed below. Doing so 2556 layout should also conform to the standards discussed below. Doing so
2944 makes it easy to include your package into the larger framework of 2557 makes it easy to include your package into the larger framework of
2945 all GNU software. 2558 all GNU software.
2946 2559
2947 @menu 2560 @menu
2948 * Configuration:: How Configuration Should Work 2561 * Configuration:: How Configuration Should Work
2949 * Makefile Conventions:: Makefile Conventions 2562 * Makefile Conventions:: Makefile Conventions
2950 * Releases:: Making Releases 2563 * Releases:: Making Releases
2951 @end menu 2564 @end menu
2952 2565
2953 @node Configuration 2566 @node Configuration
2954 @section How Configuration Should Work 2567 @section How Configuration Should Work
2955 2568
3018 2631
3019 The @code{configure} script needs to be able to decode all plausible 2632 The @code{configure} script needs to be able to decode all plausible
3020 alternatives for how to describe a machine. Thus, @samp{sun3-sunos4.1} 2633 alternatives for how to describe a machine. Thus, @samp{sun3-sunos4.1}
3021 would be a valid alias. For many programs, @samp{vax-dec-ultrix} would 2634 would be a valid alias. For many programs, @samp{vax-dec-ultrix} would
3022 be an alias for @samp{vax-dec-bsd}, simply because the differences 2635 be an alias for @samp{vax-dec-bsd}, simply because the differences
3023 between Ultrix and BSD are rarely noticeable, but a few programs 2636 between Ultrix and @sc{BSD} are rarely noticeable, but a few programs
3024 might need to distinguish them. 2637 might need to distinguish them.
3025 @c Real 4.4BSD now runs on some Suns. 2638 @c Real 4.4BSD now runs on some Suns.
3026 2639
3027 There is a shell script called @file{config.sub} that you can use 2640 There is a shell script called @file{config.sub} that you can use
3028 as a subroutine to validate system types and canonicalize aliases. 2641 as a subroutine to validate system types and canonicalize aliases.
3050 to work with @var{package}. 2663 to work with @var{package}.
3051 2664
3052 @c Giving an optional @var{parameter} of 2665 @c Giving an optional @var{parameter} of
3053 @c @samp{no} should omit @var{package}, if it is used by default. 2666 @c @samp{no} should omit @var{package}, if it is used by default.
3054 2667
3055 Possible values of @var{package} include 2668 Possible values of @var{package} include @samp{x}, @samp{x-toolkit},
3056 @samp{gnu-as} (or @samp{gas}), @samp{gnu-ld}, @samp{gnu-libc}, 2669 @samp{gnu-as} (or @samp{gas}), @samp{gnu-ld}, @samp{gnu-libc}, and
3057 @samp{gdb}, 2670 @samp{gdb}.
3058 @samp{x},
3059 and
3060 @samp{x-toolkit}.
3061 2671
3062 Do not use a @samp{--with} option to specify the file name to use to 2672 Do not use a @samp{--with} option to specify the file name to use to
3063 find certain files. That is outside the scope of what @samp{--with} 2673 find certain files. That is outside the scope of what @samp{--with}
3064 options are for. 2674 options are for.
3065 2675
3122 @raisesections 2732 @raisesections
3123 2733
3124 @node Releases 2734 @node Releases
3125 @section Making Releases 2735 @section Making Releases
3126 2736
3127 Package the distribution of @code{Foo version 69.96} up in a gzipped tar 2737 Package the distribution of Foo version 69.96 in a gzipped tar file
3128 file with the name @file{foo-69.96.tar.gz}. It should unpack into a 2738 named @file{foo-69.96.tar.gz}. It should unpack into a subdirectory
3129 subdirectory named @file{foo-69.96}. 2739 named @file{foo-69.96}.
3130 2740
3131 Building and installing the program should never modify any of the files 2741 Building and installing the program should never modify any of the files
3132 contained in the distribution. This means that all the files that form 2742 contained in the distribution. This means that all the files that form
3133 part of the program in any way must be classified into @dfn{source 2743 part of the program in any way must be classified into @dfn{source
3134 files} and @dfn{non-source files}. Source files are written by humans 2744 files} and @dfn{non-source files}. Source files are written by humans
3135 and never changed automatically; non-source files are produced from 2745 and never changed automatically; non-source files are produced from
3136 source files by programs under the control of the Makefile. 2746 source files by programs under the control of the Makefile.
3137
3138 The distribution should contain a file named @file{README} which gives
3139 the name of the package, and a general description of what it does. It
3140 is also good to explain the purpose of each of the first-level
3141 subdirectories in the package, if there are any. The @file{README} file
3142 should either state the version number of the package, or refer to where
3143 in the package it can be found.
3144
3145 The @file{README} file should refer to the file @file{INSTALL}, which
3146 should contain an explanation of the installation procedure.
3147
3148 The @file{README} file should also refer to the file which contains the
3149 copying conditions. The GNU GPL, if used, should be in a file called
3150 @file{COPYING}. If the GNU LGPL is used, it should be in a file called
3151 @file{COPYING.LIB}.
3152 2747
3153 Naturally, all the source files must be in the distribution. It is okay 2748 Naturally, all the source files must be in the distribution. It is okay
3154 to include non-source files in the distribution, provided they are 2749 to include non-source files in the distribution, provided they are
3155 up-to-date and machine-independent, so that building the distribution 2750 up-to-date and machine-independent, so that building the distribution
3156 normally will never modify them. We commonly include non-source files 2751 normally will never modify them. We commonly include non-source files
3172 Make sure that all the files in the distribution are world-readable. 2767 Make sure that all the files in the distribution are world-readable.
3173 2768
3174 Make sure that no file name in the distribution is more than 14 2769 Make sure that no file name in the distribution is more than 14
3175 characters long. Likewise, no file created by building the program 2770 characters long. Likewise, no file created by building the program
3176 should have a name longer than 14 characters. The reason for this is 2771 should have a name longer than 14 characters. The reason for this is
3177 that some systems adhere to a foolish interpretation of the @sc{posix} 2772 that some systems adhere to a foolish interpretation of the POSIX
3178 standard, and refuse to open a longer name, rather than truncating as 2773 standard, and refuse to open a longer name, rather than truncating as
3179 they did in the past. 2774 they did in the past.
3180 2775
3181 Don't include any symbolic links in the distribution itself. If the tar 2776 Don't include any symbolic links in the distribution itself. If the tar
3182 file contains symbolic links, then people cannot even unpack it on 2777 file contains symbolic links, then people cannot even unpack it on
3200 getopt, obstack, or termcap, include them in the distribution file. 2795 getopt, obstack, or termcap, include them in the distribution file.
3201 Leaving them out would make the distribution file a little smaller at 2796 Leaving them out would make the distribution file a little smaller at
3202 the expense of possible inconvenience to a user who doesn't know what 2797 the expense of possible inconvenience to a user who doesn't know what
3203 other files to get. 2798 other files to get.
3204 2799
3205 @node References
3206 @chapter References to Non-Free Software and Documentation
3207
3208 A GNU program should not recommend use of any non-free program. We
3209 can't stop some people from writing proprietary programs, or stop other
3210 people from using them. But we can and should avoid helping to
3211 advertise them to new customers.
3212
3213 Sometimes it is important to mention how to build your package on top of
3214 some non-free operating system or other non-free base package. In such
3215 cases, please mention the name of the non-free package or system in the
3216 briefest possible way. Don't include any references for where to find
3217 more information about the proprietary program. The goal should be that
3218 people already using the proprietary program will get the advice they
3219 need about how to use your free program, while people who don't already
3220 use the proprietary program will not see anything to encourage them to
3221 take an interest in it.
3222
3223 Likewise, a GNU package should not refer the user to any non-free
3224 documentation for free software. The need for free documentation to go
3225 with free software is now a major focus of the GNU project; to show that
3226 we are serious about the need for free documentation, we must not
3227 undermine our position by recommending use of documentation that isn't
3228 free.
3229
3230 @contents 2800 @contents
3231 2801
3232 @bye 2802 @bye