1 GNU make NEWS -*-indented-text-*-
2 History of user-visible changes.
5 Copyright (C) 1992,93,94,95,96,97,98,1999 Free Software Foundation, Inc.
6 See the end for copying conditions.
8 All changes mentioned here are more fully described in the GNU make
9 manual, which is contained in this distribution as the file make.texinfo.
11 Please send GNU make bug reports to bug-make@gnu.org.
12 See the README file and the GNU make manual for details on sending bug
17 * Two new functions, $(error ...) and $(warning ...) are available. The
18 former will cause make to fail and exit immediately upon expansion of
19 the function, with the text provided as the error message. The latter
20 causes the text provided to be printed as a warning message, but make
23 * A new function $(call ...) is available. This allows users to create
24 their own parameterized macros and invoke them later. Original
25 implementation of this function was provided by Han-Wen Nienhuys
28 * A new function $(if ...) is available. It provides if-then-else
29 capabilities in a builtin function. Original implementation of this
30 function was provided by Han-Wen Nienhuys <hanwen@cs.uu.nl>.
32 * Make defines a new variable, .LIBPATTERNS. This variable controls how
33 library dependency expansion (dependencies like ``-lfoo'') is performed.
35 * Make accepts CRLF sequences as well as traditional LF, for
36 compatibility with makefiles created on other operating systems.
38 * Make accepts a new option: -R, or --no-builtin-variables. This option
39 disables the definition of the rule-specific builtin variables (CC,
40 LD, AR, etc.). Specifying this option forces -r (--no-builtin-rules)
43 * A "job server" feature, suggested by Howard Chu <hyc@highlandsun.com>.
45 On systems that support POSIX pipe(2) semantics, GNU make can now pass
46 -jN options to submakes rather than forcing them all to use -j1. The
47 top make and all its sub-make processes use a pipe to communicate with
48 each other to ensure that no more than N jobs are started across all
49 makes. To get the old behavior of -j back, you can configure make
50 with the --disable-job-server option.
52 * The confusing term "dependency" has been replaced by the more accurate
53 and standard term "prerequisite", both in the manual and in all GNU make
56 * GNU make supports the "big archive" library format introduced in AIX 4.3.
58 * GNU make supports large files on AIX, HP-UX, and IRIX. These changes
59 were provided by Paul Eggert <eggert@twinsun.com>. (Large file
60 support for Solaris and Linux was introduced in 3.77, but the
61 configuration had issues: these have also been resolved).
63 * The Windows 95/98/NT (W32) version of GNU make now has native support
64 for the Cygnus Cygwin release B20.1 shell (bash).
66 * The GNU make regression test suite, long available separately "under
67 the table", has been integrated into the release. You can invoke it
68 by running "make check" in the distribution. Note that it requires
69 Perl (either Perl 4 or Perl 5) to run.
73 * Implement BSD make's "?=" variable assignment operator. The variable
74 is assigned the specified value only if that variable is not already
77 * Make defines a new variable, "CURDIR", to contain the current working
78 directory (after the -C option, if any, has been processed).
79 Modifying this variable has no effect on the operation of make.
81 * Make defines a new default RCS rule, for new-style master file
82 storage: ``% :: RCS/%'' (note no ``,v'' suffix).
84 Make defines new default rules for DOS-style C++ file naming
85 conventions, with ``.cpp'' suffixes. All the same rules as for
86 ``.cc'' and ``.C'' suffixes are provided, along with LINK.cpp and
87 COMPILE.cpp macros (which default to the same value as LINK.cc and
88 COMPILE.cc). Note CPPFLAGS is still C preprocessor flags! You should
89 use CXXFLAGS to change C++ compiler flags.
91 * A new feature, "target-specific variable values", has been added.
92 This is a large change so please see the appropriate sections of the
93 manual for full details. Briefly, syntax like this:
95 TARGET: VARIABLE = VALUE
97 defines VARIABLE as VALUE within the context of TARGET. This is
98 similar to SunOS make's "TARGET := VARIABLE = VALUE" feature. Note
99 that the assignment may be of any type, not just recursive, and that
100 the override keyword is available.
102 COMPATIBILITY: This new syntax means that if you have any rules where
103 the first or second dependency has an equal sign (=) in its name,
104 you'll have to escape them with a backslash: "foo : bar\=baz".
105 Further, if you have any dependencies which already contain "\=",
106 you'll have to escape both of them: "foo : bar\\\=baz".
108 * A new appendix listing the most common error and warning messages
109 generated by GNU make, with some explanation, has been added to the
110 GNU make User's Manual.
112 * Updates to the GNU make Customs library support (see README.customs).
114 * Updates to the Windows 95/NT port from Rob Tulloh (see README.W32),
115 and to the DOS port from Eli Zaretski (see README.DOS).
119 * Small (but serious) bug fix. Quick rollout to get into the GNU source CD.
123 * GNU make now uses automake to control Makefile.in generation. This
124 should make it more consistent with the GNU standards.
126 * VPATH functionality has been changed to incorporate the VPATH+ patch,
127 previously maintained by Paul Smith <psmith@baynetworks.com>. See the
130 * Make defines a new variable, `MAKECMDGOALS', to contain the goals that
131 were specified on the command line, if any. Modifying this variable
132 has no effect on the operation of make.
134 * A new function, `$(wordlist S,E,TEXT)', is available: it returns a
135 list of words from number S to number E (inclusive) of TEXT.
137 * Instead of an error, detection of future modification times gives a
138 warning and continues. The warning is repeated just before GNU make
139 exits, so it is less likely to be lost.
141 * Fix the $(basename) and $(suffix) functions so they only operate on
142 the last filename, not the entire string:
144 Command Old Result New Result
145 ------- ---------- ----------
147 $(basename a.b/c) a a.b/c
149 $(suffix a.b/c) b/c <empty>
151 * The $(strip) function now removes newlines as well as TABs and spaces.
153 * The $(shell) function now changes CRLF (\r\n) pairs to a space as well
156 * Updates to the Windows 95/NT port from Rob Tulloh (see README.W32).
158 * Eli Zaretskii has updated the port to 32-bit protected mode on MSDOS
159 and MS-Windows, building with the DJGPP v2 port of GNU C/C++ compiler
160 and utilities. See README.DOS for details, and direct all questions
161 concerning this port to Eli Zaretskii <eliz@is.elta.co.il> or DJ
162 Delorie <dj@delorie.com>.
164 * John W. Eaton has updated the VMS port to support libraries and VPATH.
168 * The directory messages printed by `-w' and implicitly in sub-makes,
169 are now omitted if Make runs no commands and has no other messages to print.
171 * Make now detects files that for whatever reason have modification times
172 in the future and gives an error. Files with such impossible timestamps
173 can result from unsynchronized clocks, or archived distributions
174 containing bogus timestamps; they confuse Make's dependency engine
177 * The new directive `sinclude' is now recognized as another name for
178 `-include', for compatibility with some other Makes.
180 * Aaron Digulla has contributed a port to AmigaDOS. See README.Amiga for
181 details, and direct all Amiga-related questions to <digulla@fh-konstanz.de>.
183 * Rob Tulloh of Tivoli Systems has contributed a port to Windows NT or 95.
184 See README.W32 for details, and direct all Windows-related questions to
185 <rob_tulloh@tivoli.com>.
189 * Converted to use Autoconf version 2, so `configure' has some new options.
190 See INSTALL for details.
192 * You can now send a SIGUSR1 signal to Make to toggle printing of debugging
193 output enabled by -d, at any time during the run.
197 * DJ Delorie has ported Make to MS-DOS using the GO32 extender.
198 He is maintaining the DOS port, not the GNU Make maintainer;
199 please direct bugs and questions for DOS to <djgpp@sun.soe.clarkson.edu>.
200 MS-DOS binaries are available for FTP from ftp.simtel.net in
201 /pub/simtelnet/gnu/djgpp/.
203 * The `MAKEFLAGS' variable (in the environment or in a makefile) can now
204 contain variable definitions itself; these are treated just like
205 command-line variable definitions. Make will automatically insert any
206 variable definitions from the environment value of `MAKEFLAGS' or from
207 the command line, into the `MAKEFLAGS' value exported to children. The
208 `MAKEOVERRIDES' variable previously included in the value of `$(MAKE)'
209 for sub-makes is now included in `MAKEFLAGS' instead. As before, you can
210 reset `MAKEOVERRIDES' in your makefile to avoid putting all the variables
211 in the environment when its size is limited.
213 * If `.DELETE_ON_ERROR' appears as a target, Make will delete the target of
214 a rule if it has changed when its commands exit with a nonzero status,
215 just as when the commands get a signal.
217 * The automatic variable `$+' is new. It lists all the dependencies like
218 `$^', but preserves duplicates listed in the makefile. This is useful
219 for linking rules, where library files sometimes need to be listed twice
222 * You can now specify the `.IGNORE' and `.SILENT' special targets with
223 dependencies to limit their effects to those files. If a file appears as
224 a dependency of `.IGNORE', then errors will be ignored while running the
225 commands to update that file. Likewise if a file appears as a dependency
226 of `.SILENT', then the commands to update that file will not be printed
227 before they are run. (This change was made to conform to POSIX.2.)
231 * The automatic variables `$(@D)', `$(%D)', `$(*D)', `$(<D)', `$(?D)', and
232 `$(^D)' now omit the trailing slash from the directory name. (This change
233 was made to comply with POSIX.2.)
235 * The source distribution now includes the Info files for the Make manual.
236 There is no longer a separate distribution containing Info and DVI files.
238 * You can now set the variables `binprefix' and/or `manprefix' in
239 Makefile.in (or on the command line when installing) to install GNU make
240 under a name other than `make' (i.e., ``make binprefix=g install''
241 installs GNU make as `gmake').
243 * The built-in Texinfo rules use the new variables `TEXI2DVI_FLAGS' for
244 flags to the `texi2dvi' script, and `MAKEINFO_FLAGS' for flags to the
247 * The exit status of Make when it runs into errors is now 2 instead of 1.
248 The exit status is 1 only when using -q and some target is not up to date.
249 (This change was made to comply with POSIX.2.)
253 * It is no longer a fatal error to have a NUL character in a makefile.
254 You should never put a NUL in a makefile because it can have strange
255 results, but otherwise empty lines full of NULs (such as produced by
256 the `xmkmf' program) will always work fine.
258 * The error messages for nonexistent included makefiles now refer to the
259 makefile name and line number where the `include' appeared, so Emacs's
260 C-x ` command takes you there (in case it's a typo you need to fix).
264 * Implicit rule search for archive member references is now done in the
265 opposite order from previous versions: the whole target name `LIB(MEM)'
266 first, and just the member name and parentheses `(MEM)' second.
268 * Make now gives an error for an unterminated variable or function reference.
269 For example, `$(foo' with no matching `)' or `${bar' with no matching `}'.
271 * The new default variable `MAKE_VERSION' gives the version number of
272 Make, and a string describing the remote job support compiled in (if any).
273 Thus the value (in this release) is something like `3.69' or `3.69-Customs'.
275 * Commands in an invocation of the `shell' function are no longer run with
276 a modified environment like target commands are. As in versions before
277 3.68, they now run with the environment that `make' started with. We
278 have reversed the change made in version 3.68 because it turned out to
279 cause a paradoxical situation in cases like:
281 export variable = $(shell echo value)
283 When Make attempted to put this variable in the environment for a target
284 command, it would try expand the value by running the shell command
285 `echo value'. In version 3.68, because it constructed an environment
286 for that shell command in the same way, Make would begin to go into an
287 infinite loop and then get a fatal error when it detected the loop.
289 * The commands given for `.DEFAULT' are now used for phony targets with no
294 * You can list several archive member names inside parenthesis:
295 `lib(mem1 mem2 mem3)' is equivalent to `lib(mem1) lib(mem2) lib(mem3)'.
297 * You can use wildcards inside archive member references. For example,
298 `lib(*.o)' expands to all existing members of `lib' whose names end in
299 `.o' (e.g. `lib(a.o) lib(b.o)'); `*.a(*.o)' expands to all such members
300 of all existing files whose names end in `.a' (e.g. `foo.a(a.o)
301 foo.a(b.o) bar.a(c.o) bar.a(d.o)'.
303 * A suffix rule `.X.a' now produces two pattern rules:
304 (%.o): %.X # Previous versions produced only this.
305 %.a: %.X # Now produces this as well, just like other suffixes.
307 * The new flag `--warn-undefined-variables' says to issue a warning message
308 whenever Make expands a reference to an undefined variable.
310 * The new `-include' directive is just like `include' except that there is
311 no error (not even a warning) for a nonexistent makefile.
313 * Commands in an invocation of the `shell' function are now run with a
314 modified environment like target commands are, so you can use `export' et
315 al to set up variables for them. They used to run with the environment
316 that `make' started with.
320 * `make --version' (or `make -v') now exits immediately after printing
325 * Make now supports long-named members in `ar' archive files.
329 * Make now supports the `+=' syntax for a variable definition which appends
330 to the variable's previous value. See the section `Appending More Text
331 to Variables' in the manual for full details.
333 * The new option `--no-print-directory' inhibits the `-w' or
334 `--print-directory' feature. Make turns on `--print-directory'
335 automatically if you use `-C' or `--directory', and in sub-makes; some
336 users have found this behavior undesirable.
338 * The built-in implicit rules now support the alternative extension
339 `.txinfo' for Texinfo files, just like `.texinfo' and `.texi'.
343 * Make now uses a standard GNU `configure' script. See the new file
344 INSTALL for the new (and much simpler) installation procedure.
346 * There is now a shell script to build Make the first time, if you have no
347 other `make' program. `build.sh' is created by `configure'; see README.
349 * GNU Make now completely conforms to the POSIX.2 specification for `make'.
351 * Elements of the `$^' and `$?' automatic variables that are archive
352 member references now list only the member name, as in Unix and POSIX.2.
354 * You should no longer ever need to specify the `-w' switch, which prints
355 the current directory before and after Make runs. The `-C' switch to
356 change directory, and recursive use of Make, now set `-w' automatically.
358 * Multiple double-colon rules for the same target will no longer have their
359 commands run simultaneously under -j, as this could result in the two
360 commands trying to change the file at the same time and interfering with
363 * The `SHELL' variable is now never taken from the environment.
364 Each makefile that wants a shell other than the default (/bin/sh) must
365 set SHELL itself. SHELL is always exported to child processes.
366 This change was made for compatibility with POSIX.2.
368 * Make now accepts long options. There is now an informative usage message
369 that tells you what all the options are and what they do. Try `make --help'.
371 * There are two new directives: `export' and `unexport'. All variables are
372 no longer automatically put into the environments of the commands that
373 Make runs. Instead, only variables specified on the command line or in
374 the environment are exported by default. To export others, use:
376 or you can define variables with:
377 export VARIABLE = VALUE
379 export VARIABLE := VALUE
383 .EXPORT_ALL_VARIABLES:
384 to get the old behavior. See the node `Variables/Recursion' in the manual
385 for a full description.
387 * The commands from the `.DEFAULT' special target are only applied to
388 targets which have no rules at all, not all targets with no commands.
389 This change was made for compatibility with Unix make.
391 * All fatal error messages now contain `***', so they are easy to find in
394 * Dependency file names like `-lNAME' are now replaced with the actual file
395 name found, as with files found by normal directory search (VPATH).
396 The library file `libNAME.a' may now be found in the current directory,
397 which is checked before VPATH; the standard set of directories (/lib,
398 /usr/lib, /usr/local/lib) is now checked last.
399 See the node `Libraries/Search' in the manual for full details.
401 * A single `include' directive can now specify more than one makefile to
404 You can also use shell file name patterns in an `include' directive:
407 * The default directories to search for included makefiles, and for
408 libraries specified with `-lNAME', are now set by configuration.
410 * You can now use blanks as well as colons to separate the directories in a
411 search path for the `vpath' directive or the `VPATH' variable.
413 * You can now use variables and functions in the left hand side of a
414 variable assignment, as in "$(foo)bar = value".
416 * The `MAKE' variable is always defined as `$(MAKE_COMMAND) $(MAKEOVERRIDES)'.
417 The `MAKE_COMMAND' variable is now defined to the name with which make
420 * The built-in rules for C++ compilation now use the variables `$(CXX)' and
421 `$(CXXFLAGS)' instead of `$(C++)' and `$(C++FLAGS)'. The old names had
422 problems with shells that cannot have `+' in environment variable names.
424 * The value of a recursively expanded variable is now expanded when putting
425 it into the environment for child processes. This change was made for
426 compatibility with Unix make.
428 * A rule with no targets before the `:' is now accepted and ignored.
429 This change was made for compatibility with SunOS 4 make.
430 We do not recommend that you write your makefiles to take advantage of this.
432 * The `-I' switch can now be used in MAKEFLAGS, and are put there
433 automatically just like other switches.
437 * Built-in rules for C++ source files with the `.C' suffix.
438 We still recommend that you use `.cc' instead.
440 * If commands are given too many times for a single target,
441 the last set given is used, and a warning message is printed.
443 * Error messages about makefiles are in standard GNU error format,
444 so C-x ` in Emacs works on them.
446 * Dependencies of pattern rules which contain no % need not actually exist
447 if they can be created (just like dependencies which do have a %).
451 * A message is always printed when Make decides there is nothing to be done.
452 It used to be that no message was printed for top-level phony targets
453 (because "`phony' is up to date" isn't quite right). Now a different
454 message "Nothing to be done for `phony'" is printed in that case.
456 * Archives on AIX now supposedly work.
458 * When the commands specified for .DEFAULT are used to update a target,
459 the $< automatic variable is given the same value as $@ for that target.
460 This is how Unix make behaves, and this behavior is mandated by POSIX.2.
464 * The -n, -q, and -t options are not put in the `MAKEFLAGS' and `MFLAG'
465 variables while remaking makefiles, so recursive makes done while remaking
466 makefiles will behave properly.
468 * If the special target `.NOEXPORT' is specified in a makefile,
469 only variables that came from the environment and variables
470 defined on the command line are exported.
474 * Suffix rules may have dependencies (which are ignored).
478 * Dependencies of the form `-lLIB' are searched for as /usr/local/lib/libLIB.a
479 as well as libLIB.a in /usr/lib, /lib, the current directory, and VPATH.
483 * There is now a Unix man page for GNU Make. It is certainly not a replacement
484 for the Texinfo manual, but it documents the basic functionality and the
485 switches. For full documentation, you should still read the Texinfo manual.
486 Thanks to Dennis Morse of Stanford University for contributing the initial
489 * Variables which are defined by default (e.g., `CC') will no longer be put
490 into the environment for child processes. (If these variables are reset by the
491 environment, makefiles, or the command line, they will still go into the
494 * Makefiles which have commands but no dependencies (and thus are always
495 considered out of date and in need of remaking), will not be remade (if they
496 were being remade only because they were makefiles). This means that GNU
497 Make will no longer go into an infinite loop when fed the makefiles that
498 `imake' (necessary to build X Windows) produces.
500 * There is no longer a warning for using the `vpath' directive with an explicit
501 pathname (instead of a `%' pattern).
505 * When removing intermediate files, only one `rm' command line is printed,
506 listing all file names.
508 * There are now automatic variables `$(^D)', `$(^F)', `$(?D)', and `$(?F)'.
509 These are the directory-only and file-only versions of `$^' and `$?'.
511 * Library dependencies given as `-lNAME' will use "libNAME.a" in the current
512 directory if it exists.
514 * The automatic variable `$($/)' is no longer defined.
516 * Leading `+' characters on a command line make that line be executed even
517 under -n, -t, or -q (as if the line contained `$(MAKE)').
519 * For command lines containing `$(MAKE)', `${MAKE}', or leading `+' characters,
520 only those lines are executed, not their entire rules.
521 (This is how Unix make behaves for lines containing `$(MAKE)' or `${MAKE}'.)
525 * Filenames in rules will now have ~ and ~USER expanded.
527 * The `-p' output has been changed so it can be used as a makefile.
528 (All information that isn't specified by makefiles is prefaced with comment
533 * The % character can be quoted with backslash in implicit pattern rules,
534 static pattern rules, `vpath' directives, and `patsubst', `filter', and
535 `filter-out' functions. A warning is issued if a `vpath' directive's
536 pattern contains no %.
538 * The `wildcard' variable expansion function now expands ~ and ~USER.
540 * Messages indicating failed commands now contain the target name:
541 make: *** [target] Error 1
543 * The `-p' output format has been changed somewhat to look more like
544 makefile rules and to give all information that Make has about files.
550 * The `-l' switch with no argument removes any previous load-average limit.
552 * When the `-w' switch is in effect, and Make has updated makefiles,
553 it will write a `Leaving directory' messagfe before re-executing itself.
554 This makes the `directory change tracking' changes to Emacs's compilation
555 commands work properly.
559 * The automatic variable `$*' is now defined for explicit rules,
560 as it is in Unix make.
564 * The `-j' switch is now put in the MAKEFLAGS and MFLAGS variables when
565 specified without an argument (indicating infinite jobs).
566 The `-l' switch is not always put in the MAKEFLAGS and MFLAGS variables.
568 * Make no longer checks hashed directories after running commands.
569 The behavior implemented in 3.41 caused too much slowdown.
573 * A dependency is NOT considered newer than its dependent if
574 they have the same modification time. The behavior implemented
575 in 3.43 conflicts with RCS.
579 * Dependency loops are no longer fatal errors.
581 * A dependency is considered newer than its dependent if
582 they have the same modification time.
586 * The variables F77 and F77FLAGS are now set by default to $(FC) and
587 $(FFLAGS). Makefiles designed for System V make may use these variables in
588 explicit rules and expect them to be set. Unfortunately, there is no way to
589 make setting these affect the Fortran implicit rules unless FC and FFLAGS
590 are not used (and these are used by BSD make).
594 * Make now checks to see if its hashed directories are changed by commands.
595 Other makes that hash directories (Sun, 4.3 BSD) don't do this.
599 * The `shell' function no longer captures standard error output.
603 * A file beginning with a dot can be the default target if it also contains
604 a slash (e.g., `../bin/foo'). (Unix make allows this as well.)
608 * Archive member names are truncated to 15 characters.
610 * Yet more USG stuff.
612 * Minimal support for Microport System V (a 16-bit machine and a
613 brain-damaged compiler). This has even lower priority than other USG
614 support, so if it gets beyond trivial, I will take it out completely.
616 * Revamped default implicit rules (not much visible change).
618 * The -d and -p options can come from the environment.
622 * Improved support for USG and HPUX (hopefully).
624 * A variable reference like `$(foo:a=b)', if `a' contains a `%', is
625 equivalent to `$(patsubst a,b,$(foo))'.
627 * Defining .DEFAULT with no deps or commands clears its commands.
629 * New default implicit rules for .S (cpp, then as), and .sh (copy and make
630 executable). All default implicit rules that use cpp (even indirectly), use
635 * Giving the -j option with no arguments gives you infinite jobs.
639 * New option: "-l LOAD" says not to start any new jobs while others are
640 running if the load average is not below LOAD (a floating-point number).
642 * There is support in place for implementations of remote command execution
643 in Make. See the file remote.c.
647 * No more than 10 directories will be kept open at once.
648 (This number can be changed by redefining MAX_OPEN_DIRECTORIES in dir.c.)
652 * Archive files will have their modification times recorded before doing
653 anything that might change their modification times by updating an archive
658 * The `MAKELEVEL' variable is defined for use by makefiles.
662 * The recursion level indications in error messages are much shorter than
663 they were in version 3.14.
667 * Leading spaces before directives are ignored (as documented).
669 * Included makefiles can determine the default goal target.
670 (System V Make does it this way, so we are being compatible).
674 * Variables that are defaults built into Make will not be put in the
675 environment for children. This just saves some environment space and,
676 except under -e, will be transparent to sub-makes.
678 * Error messages from sub-makes will indicate the level of recursion.
680 * Hopefully some speed-up for large directories due to a change in the
681 directory hashing scheme.
683 * One child will always get a standard input that is usable.
685 * Default makefiles that don't exist will be remade and read in.
689 * Count parentheses inside expansion function calls so you can
690 have nested calls: `$(sort $(foreach x,a b,$(x)))'.
694 * Several bug fixes, including USG and Sun386i support.
696 * `shell' function to expand shell commands a la `
698 * If the `-d' flag is given, version information will be printed.
700 * The `-c' option has been renamed to `-C' for compatibility with tar.
702 * The `-p' option no longer inhibits other normal operation.
704 * Makefiles will be updated and re-read if necessary.
706 * Can now run several commands at once (parallelism), -j option.
708 * Error messages will contain the level of Make recursion, if any.
710 * The `MAKEFLAGS' and `MFLAGS' variables will be scanned for options after
713 * A double-colon rule with no dependencies will always have its commands run.
714 (This is how both the BSD and System V versions of Make do it.)
718 (Changes from versions 1 through 3.05 were never recorded. Sorry.)
720 ----------------------------------------------------------------------
721 Copyright information:
723 Permission is granted to anyone to make or distribute verbatim copies
724 of this document as received, in any medium, provided that the
725 copyright notice and this permission notice are preserved, thus
726 giving the recipient permission to redistribute in turn.
728 Permission is granted to distribute modified versions of this
729 document, or of portions of it, under the above conditions, provided
730 also that they carry prominent notices stating who last changed them.