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GNU Info File | 1994-11-17 | 44KB | 1,198 lines

This is Info file ../standards.info, produced by Makeinfo-1.55 from the input file ../standards.texi. START-INFO-DIR-ENTRY * Standards: (standards). GNU coding standards. END-INFO-DIR-ENTRY 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. 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. File: standards.info, Node: Syntactic Conventions, Next: Names, Prev: Comments, Up: Top Clean Use of C Constructs ************************* Please explicitly declare all arguments to functions. Don't omit them just because they are `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 `extern' declarations inside functions. It used to be common practice to use the same local variables (with names like `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: int foo, bar; write either this: int foo, bar; or this: int foo; int bar; (If they are global variables, each should have a comment preceding it anyway.) When you have an `if'-`else' statement nested in another `if' statement, always put braces around the `if'-`else'. Thus, never write like this: if (foo) if (bar) win (); else lose (); always like this: if (foo) { if (bar) win (); else lose (); } If you have an `if' statement nested inside of an `else' statement, either write `else if' on one line, like this, if (foo) ... else if (bar) ... with its `then'-part indented like the preceding `then'-part, or write the nested `if' within braces like this: if (foo) ... else { if (bar) ... } 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 `if'-conditions. For example, don't write this: if ((foo = (char *) malloc (sizeof *foo)) == 0) fatal ("virtual memory exhausted"); instead, write this: foo = (char *) malloc (sizeof *foo); if (foo == 0) fatal ("virtual memory exhausted"); Don't make the program ugly to placate `lint'. Please don't insert any casts to `void'. Zero without a cast is perfectly fine as a null pointer constant. File: standards.info, Node: Names, Next: Using Extensions, Prev: Syntactic Conventions, Up: Top 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 `enum' constants, and for name-prefixes that follow a uniform convention. For example, you should use names like `ignore_space_change_flag'; don't use names like `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, /* Ignore changes in horizontal whitespace (-b). */ int ignore_space_change_flag; When you want to define names with constant integer values, use `enum' rather than `#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 `doschk' to test for this. `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. File: standards.info, Node: Using Extensions, Next: System Functions, Prev: Names, Up: Top 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" `INLINE' and define that as a macro to expand into either `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 ANSI C, using the ANSI C features is effectively using a GNU extension, so the same considerations apply. (Except for ANSI features that we discourage, such as trigraphs--don't ever use them.) File: standards.info, Node: System Functions, Next: Semantics, Prev: Using Extensions, Up: Top 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. * Don't use the value of `sprintf'. It returns the number of characters written on some systems, but not on all systems. * 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. * 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. * In particular, don't unconditionally declare `malloc' or `realloc'. Most GNU programs use those functions just once, in functions conventionally named `xmalloc' and `xrealloc'. These functions call `malloc' and `realloc', respectively, and check the results. Because `xmalloc' and `xrealloc' are defined in your program, you can declare them in other files without any risk of type conflict. On most systems, `int' is the same length as a pointer; thus, the calls to `malloc' and `realloc' work fine. For the few exceptional systems (mostly 64-bit machines), you can use *conditionalized* declarations of `malloc' and `realloc'--or put these declarations in configuration files specific to those systems. * The string functions require special treatment. Some Unix systems have a header file `string.h'; other have `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. * 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: strcpy strncpy strcat strncat strlen strcmp strncmp strchr strrchr 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 `int', and perhaps in other cases. It is trivial to avoid using their values, so do that. The compare functions and `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 *conditionally* on a few systems. The search functions must be declared to return `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 `index' and `rindex'; other systems use the names `strchr' and `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 `strchr' and `strrchr'.) Declare both of those names as functions returning `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 `strchr' and `strrchr' throughout: #ifndef HAVE_STRCHR #define strchr index #endif #ifndef HAVE_STRRCHR #define strrchr rindex #endif char *strchr (); char *strrchr (); Here we assume that `HAVE_STRCHR' and `HAVE_STRRCHR' are macros defined in systems where the corresponding functions exist. One way to get them properly defined is to use Autoconf. File: standards.info, Node: Semantics, Next: Errors, Prev: System Functions, Up: Top Program Behavior for All Programs ********************************* Avoid arbitrary limits on the length or number of *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 *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 `perror' or equivalent) in *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 `malloc' or `realloc' to see if it returned zero. Check `realloc' even if you are making the block smaller; in a system that rounds block sizes to a power of 2, `realloc' may get a different block if you ask for less space. In Unix, `realloc' can destroy the storage block if it returns zero. GNU `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 `malloc'. You must expect `free' to alter the contents of the block that was freed. Anything you want to fetch from the block, you must fetch before calling `free'. If `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 `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 `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 BSD and of 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. File: standards.info, Node: Errors, Next: Libraries, Prev: Semantics, Up: Top Formatting Error Messages ************************* Error messages from compilers should look like this: SOURCE-FILE-NAME:LINENO: MESSAGE Error messages from other noninteractive programs should look like this: PROGRAM:SOURCE-FILE-NAME:LINENO: MESSAGE when there is an appropriate source file, or like this: PROGRAM: MESSAGE 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 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. File: standards.info, Node: Libraries, Next: Portability, Prev: Errors, Up: Top 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 `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 `_'. 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. File: standards.info, Node: Portability, Next: User Interfaces, Prev: Libraries, Up: Top 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 (`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 `int' object is also the address of its least-significant byte. Thus, don't make the following mistake: int c; ... while ((c = getchar()) != EOF) write(file_descriptor, &c, 1); 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. File: standards.info, Node: User Interfaces, Next: Documentation, Prev: Portability, Up: Top 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 `ls' or `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 `dir' program much like `ls' except that its default output format is always multi-column format. It is a good idea to follow the POSIX guidelines for the command-line options of a program. The easiest way to do this is to use `getopt' to parse them. Note that the GNU version of `getopt' will normally permit options anywhere among the arguments unless the special argument `--' is used. This is not what 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 `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 `--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 `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 `-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 `--version' which prints the program's version number on standard output and exits successfully, and an option `--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. `auto-check' `-a' in `recode'. `auto-reference' `-A' in `ptx'. `after-date' `-N' in `tar'. `all' `-a' in `du', `ls', `nm', `stty', `uname', and `unexpand'. `all-text' `-a' in `diff'. `almost-all' `-A' in `ls'. `append' `-a' in `etags', `tee', `time'; `-r' in `tar'. `archive' `-a' in `cp'. `archive-name' `-n' in `shar'. `arglength' `-l' in `m4'. `ascii' `-a' in `diff'. `assume-new' `-W' in Make. `assume-old' `-o' in Make. `backward-search' `-B' in etags. `basename' `-f' in `shar'. `batch' Used in GDB. `baud' Used in GDB. `before' `-b' in `tac'. `binary' `-b' in `cpio' and `diff'. `bits-per-code' `-b' in `shar'. `block-size' Used in `cpio' and `tar'. `blocks' `-b' in `head' and `tail'. `break-file' `-b' in `ptx'. `brief' Used in various programs to make output shorter. `bytes' `-c' in `head', `split', and `tail'. `c++' `-C' in `etags'. `catenate' `-A' in `tar'. Used in various programs to specify the directory to use. `changes' `-c' in `chgrp' and `chown'. `classify' `-F' in `ls'. `colons' `-c' in `recode'. `command' `-c' in `su'; `-x' in GDB. `compare' `-d' in `tar'. `compress' `-Z' in `tar' and `shar'. `concatenate' `-A' in `tar'. `confirmation' `-w' in `tar'. `context' Used in `diff'. `copyright' `-C' in `ptx' and `recode'. `core' Used in GDB. `count' `-q' in `who'. `count-links' `-l' in `du'. `create' Used in `tar' and `cpio'. `cut-mark' `-c' in `shar'. `cxref' `-x' in `etags'. `date' `-d' in `touch'. `debug' `-d' in Make and `m4'; `-t' in Bison. `define' `-D' in `m4'. `defines' `-d' in Bison and `etags'. `delete' `-D' in `tar'. `dereference' `-L' in `chgrp', `chown', `cpio', `du', `ls', and `tar'. `dereference-args' `-D' in `du'. `diacritics' `-d' in `recode'. `dictionary-order' `-d' in `look'. `diff' `-d' in `tar'. `digits' `-n' in `csplit'. `directory' Specify the directory to use, in various programs. In `ls', it means to show directories themselves rather than their contents. In `rm' and `ln', it means to not treat links to directories specially. `discard-all' `-x' in `strip'. `discard-locals' `-X' in `strip'. `diversions' `-N' in `m4'. `dry-run' `-n' in Make. `-e' in `diff'. `elide-empty-files' `-z' in `csplit'. `entire-new-file' `-N' in `diff'. `environment-overrides' `-e' in Make. `eof' `-e' in `xargs'. `epoch' Used in GDB. `error-limit' Used in Makeinfo. `error-output' `-o' in `m4'. `escape' `-b' in `ls'. `exclude-from' `-X' in `tar'. `exec' Used in GDB. `exit' `-x' in `xargs'. `exit-0' `-e' in `unshar'. `expand-tabs' `-t' in `diff'. `expression' `-e' in `sed'. `extern-only' `-g' in `nm'. `extract' `-i' in `cpio'; `-x' in `tar'. `faces' `-f' in `finger'. `fast' `-f' in `su'. `fatal-warnings' `-E' in `m4'. `file' `-f' in `info', Make, `mt', and `tar'; `-n' in `sed'; `-r' in `touch'. `file-prefix' `-b' in Bison. `file-type' `-F' in `ls'. `files-from' `-T' in `tar'. `fill-column' Used in Makeinfo. `flag-truncation' `-F' in `ptx'. `fixed-output-files' `-y' in Bison. `follow' `-f' in `tail'. `footnote-style' Used in Makeinfo. `force' `-f' in `cp', `ln', `mv', and `rm'. `force-prefix' `-F' in `shar'. `format' Used in `ls', `time', and `ptx'. `forward-search' `-F' in `etags'. `fullname' Used in GDB. `gap-size' `-g' in `ptx'. `get' `-x' in `tar'. `graphic' `-i' in `ul'. `graphics' `-g' in `recode'. `group' `-g' in `install'. `gzip' `-z' in `tar' and `shar'. `hashsize' `-H' in `m4'. `header' `-h' in `objdump' and `recode' `heading' `-H' in `who'. `help' Used to ask for brief usage information. `here-delimiter' `-d' in `shar'. `hide-control-chars' `-q' in `ls'. `idle' `-u' in `who'. `ifdef' `-D' in `diff'. `ignore' `-I' in `ls'; `-x' in `recode'. `ignore-all-space' `-w' in `diff'. `ignore-backups' `-B' in `ls'. `ignore-blank-lines' `-B' in `diff'. `ignore-case' `-f' in `look' and `ptx'; `-i' in `diff'. `ignore-errors' `-i' in Make. `ignore-file' `-i' in `ptx'. `ignore-indentation' `-S' in `etags'. `ignore-init-file' `-f' in Oleo. `ignore-interrupts' `-i' in `tee'. `ignore-matching-lines' `-I' in `diff'. `ignore-space-change' `-b' in `diff'. `ignore-zeros' `-i' in `tar'. `include' `-i' in `etags'; `-I' in `m4'. `include-dir' `-I' in Make. `incremental' `-G' in `tar'. `info' `-i', `-l', and `-m' in Finger. `initial' `-i' in `expand'. `initial-tab' `-T' in `diff'. `inode' `-i' in `ls'. `interactive' `-i' in `cp', `ln', `mv', `rm'; `-e' in `m4'; `-p' in `xargs'; `-w' in `tar'. `intermix-type' `-p' in `shar'. `jobs' `-j' in Make. `just-print' `-n' in Make. `keep-going' `-k' in Make. `keep-files' `-k' in `csplit'. `kilobytes' `-k' in `du' and `ls'. `level-for-gzip' `-g' in `shar'. `line-bytes' `-C' in `split'. `lines' Used in `split', `head', and `tail'. `link' `-l' in `cpio'. `list' `-t' in `cpio'; `-l' in `recode'. `list' `-t' in `tar'. `literal' `-N' in `ls'. `load-average' `-l' in Make. `login' Used in `su'. `machine' No listing of which programs already use this; someone should check to see if any actually do and tell `gnu@prep.ai.mit.edu'. `macro-name' `-M' in `ptx'. `mail' `-m' in `hello' and `uname'. `make-directories' `-d' in `cpio'. `makefile' `-f' in Make. `mapped' Used in GDB. `max-args' `-n' in `xargs'. `max-chars' `-n' in `xargs'. `max-lines' `-l' in `xargs'. `max-load' `-l' in Make. `max-procs' `-P' in `xargs'. `mesg' `-T' in `who'. `message' `-T' in `who'. `minimal' `-d' in `diff'. `mixed-uuencode' `-M' in `shar'. `mode' `-m' in `install', `mkdir', and `mkfifo'. `modification-time' `-m' in `tar'. `multi-volume' `-M' in `tar'. `name-prefix' `-a' in Bison. `nesting-limit' `-L' in `m4'. `net-headers' `-a' in `shar'. `new-file' `-W' in Make. `no-builtin-rules' `-r' in Make. `no-character-count' `-w' in `shar'. `no-check-existing' `-x' in `shar'. `no-create' `-c' in `touch'. `no-defines' `-D' in `etags'. `no-dereference' `-d' in `cp'. `no-keep-going' `-S' in Make. `no-lines' `-l' in Bison. `no-piping' `-P' in `shar'. `no-prof' `-e' in `gprof'. `no-sort' `-p' in `nm'. `no-split' Used in Makeinfo. `no-static' `-a' in `gprof'. `no-time' `-E' in `gprof'. `no-timestamp' `-m' in `shar'. `no-validate' Used in Makeinfo. `no-verbose' `-v' in `shar'. `no-warn' Used in various programs to inhibit warnings. `node' `-n' in `info'. `nodename' `-n' in `uname'. `nonmatching' `-f' in `cpio'. `nstuff' `-n' in `objdump'. `null' `-0' in `xargs'. `number' `-n' in `cat'. `number-nonblank' `-b' in `cat'. `numeric-sort' `-n' in `nm'. `numeric-uid-gid' `-n' in `cpio' and `ls'. Used in GDB. `old-archive' `-o' in `tar'. `old-file' `-o' in Make. `one-file-system' `-l' in `tar', `cp', and `du'. `only-file' `-o' in `ptx'. `only-prof' `-f' in `gprof'. `only-time' `-F' in `gprof'. `output' In various programs, specify the output file name. `output-prefix' `-o' in `shar'. `override' `-o' in `rm'. `overwrite' `-c' in `unshar'. `owner' `-o' in `install'. `paginate' `-l' in `diff'. `paragraph-indent' Used in Makeinfo. `parents' `-p' in `mkdir' and `rmdir'. `pass-all' `-p' in `ul'. `pass-through' `-p' in `cpio'. `port' `-P' in `finger'. `portability' `-c' in `cpio' and `tar'. `prefix-builtins' `-P' in `m4'. `prefix' `-f' in `csplit'. `preserve' Used in `tar' and `cp'. `preserve-environment' `-p' in `su'. `preserve-modification-time' `-m' in `cpio'. `preserve-order' `-s' in `tar'. `preserve-permissions' `-p' in `tar'. `print' `-l' in `diff'. `print-chars' `-L' in `cmp'. `print-data-base' `-p' in Make. `print-directory' `-w' in Make. `print-file-name' `-o' in `nm'. `print-symdefs' `-s' in `nm'. `query-user' `-X' in `shar'. `question' `-q' in Make. `quiet' Used in many programs to inhibit the usual output. *Note:* every program accepting `--quiet' should accept `--silent' as a synonym. `quote-name' `-Q' in `ls'. `rcs' `-n' in `diff'. `read-full-blocks' `-B' in `tar'. `readnow' Used in GDB. `recon' `-n' in Make. `record-number' `-R' in `tar'. `recursive' Used in `chgrp', `chown', `cp', `ls', `diff', and `rm'. `reference-limit' Used in Makeinfo. `references' `-r' in `ptx'. `regex' `-r' in `tac'. `release' `-r' in `uname'. `relocation' `-r' in `objdump'. `rename' `-r' in `cpio'. `replace' `-i' in `xargs'. `report-identical-files' `-s' in `diff'. `reset-access-time' `-a' in `cpio'. `reverse' `-r' in `ls' and `nm'. `reversed-ed' `-f' in `diff'. `right-side-defs' `-R' in `ptx'. `same-order' `-s' in `tar'. `same-permissions' `-p' in `tar'. `save' `-g' in `stty'. Used in GDB. `sentence-regexp' `-S' in `ptx'. `separate-dirs' `-S' in `du'. `separator' `-s' in `tac'. `sequence' Used by `recode' to chose files or pipes for sequencing passes. `shell' `-s' in `su'. `show-all' `-A' in `cat'. `show-c-function' `-p' in `diff'. `show-ends' `-E' in `cat'. `show-function-line' `-F' in `diff'. `show-tabs' `-T' in `cat'. `silent' Used in many programs to inhibit the usual output. *Note:* every program accepting `--silent' should accept `--quiet' as a synonym. `size' `-s' in `ls'. `sort' Used in `ls'. `sparse' `-S' in `tar'. `speed-large-files' `-H' in `diff'. `split-at' `-E' in `unshar'. `split-size-limit' `-L' in `shar'. `squeeze-blank' `-s' in `cat'. `starting-file' Used in `tar' and `diff' to specify which file within a directory to start processing with. `stdin-file-list' `-S' in `shar'. `stop' `-S' in Make. `strict' `-s' in `recode'. `strip' `-s' in `install'. `strip-all' `-s' in `strip'. `strip-debug' `-S' in `strip'. `submitter' `-s' in `shar'. `suffix' `-S' in `cp', `ln', `mv'. `suffix-format' `-b' in `csplit'. `sum' `-s' in `gprof'. `summarize' `-s' in `du'. `symbolic' `-s' in `ln'. `symbols' Used in GDB and `objdump'. `synclines' `-s' in `m4'. `sysname' `-s' in `uname'. `tabs' `-t' in `expand' and `unexpand'. `tabsize' `-T' in `ls'. `terminal' `-T' in `tput' and `ul'. `text' `-a' in `diff'. `text-files' `-T' in `shar'. `time' Used in `ls' and `touch'. `to-stdout' `-O' in `tar'. `total' `-c' in `du'. `touch' `-t' in Make, `ranlib', and `recode'. `trace' `-t' in `m4'. `traditional' `-t' in `hello'; `-G' in `m4' and `ptx'. `tty' Used in GDB. `typedefs' `-t' in `etags'. `typedefs-and-c++' `-T' in `etags'. `typeset-mode' `-t' in `ptx'. `uncompress' `-z' in `tar'. `unconditional' `-u' in `cpio'. `undefine' `-U' in `m4'. `undefined-only' `-u' in `nm'. `update' `-u' in `cp', `etags', `mv', `tar'. `uuencode' `-B' in `shar'. `vanilla-operation' `-V' in `shar'. `verbose' Print more information about progress. Many programs support this. `verify' `-W' in `tar'. `version' Print the version number. `version-control' `-V' in `cp', `ln', `mv'. `vgrind' `-v' in `etags'. `volume' `-V' in `tar'. `what-if' `-W' in Make. `whole-size-limit' `-l' in `shar'. `width' `-w' in `ls' and `ptx'. `word-regexp' `-W' in `ptx'. `writable' `-T' in `who'. `zeros' `-z' in `gprof'. File: standards.info, Node: Documentation, Next: Releases, Prev: User Interfaces, Up: Top 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 (`C-h i'). See existing GNU Texinfo files (e.g., those under the `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 `PROGRAM Invocation' or `Invoking PROGRAM', where 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 `@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 `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 `NEWS' file gets very long, move some of the older items into a file named `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. File: standards.info, Node: Releases, Prev: Documentation, Up: Top Making Releases *************** Package the distribution of Foo version 69.96 in a gzipped tar file named `foo-69.96.tar.gz'. It should unpack into a subdirectory named `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 "source files" and "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 *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 `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, `foobarhacker.c' and `foobarhacker.o' are not ambiguous; they are truncated to `foobarha.c' and `foobarha.o', which are distinct. Include in your distribution a copy of the `texinfo.tex' you used to test print any `*.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.