1 Recent changes to RCS (and possible future changes)
5 Copyright 1991, 1992, 1993, 1994, 1995 Paul Eggert
6 Distributed under license by the Free Software Foundation, Inc.
8 This file is part of RCS.
10 RCS is free software; you can redistribute it and/or modify it
11 under the terms of the GNU General Public License as published
12 by the Free Software Foundation; either version 2, or (at your
13 option) any later version.
15 RCS is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with RCS; see the file COPYING.
22 If not, write to the Free Software Foundation,
23 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
25 Report problems and direct all questions to:
27 rcs-bugs@cs.purdue.edu
30 Here is a brief summary of user-visible changes since 5.6.
33 `-kb' supports binary files.
34 `-T' preserves the modification time of RCS files.
35 `-V' prints the version number.
36 `-zLT' causes RCS to use local time in working files and logs.
37 `rcsclean -n' outputs what rcsclean would do, without actually doing it.
38 `rlog -N' omits symbolic names.
39 There is a new keyword `Name'.
40 Inserted log lines now have the same prefix as the preceding `$Log' line.
42 Most changes for RCS version 5.7 are to fix bugs and improve portability.
43 RCS now conforms to GNU configuration standards and to Posix 1003.1b-1993.
46 Features new to RCS version 5.7, and possibly incompatible
47 in minor ways with previous practice, include:
49 Inserted log lines now have the same prefix as the preceding `$Log' line.
50 E.g. if a $Log line starts with `// $Log', log lines are prefixed with `// '.
51 RCS still records the (now obsolescent) comment leader inside RCS files,
52 but it ignores the comment leader unless it is emulating older RCS versions.
53 If you plan to access a file with both old and new versions of RCS,
54 make sure its comment leader matches its `$Log' line prefix.
55 For backwards compatibility with older versions of RCS,
56 if the log prefix is `/*' or `(*' surrounded by optional white space,
57 inserted log lines contain ` *' instead of `/*' or `(*';
58 however, this usage is obsolescent and should not be relied on.
60 $Log string `Revision' times now use the same format as other times.
62 Log lines are now inserted even if -kk is specified; this simplifies merging.
64 ci's -rR option (with a nonempty R) now just specifies a revision number R.
65 In some beta versions, it also reestablished the default behavior of
66 releasing a lock and removing the working file.
67 Now, only the bare -r option does this.
69 With an empty extension, any appearance of a directory named `RCS'
70 in a pathname identifies the pathname as being that of an RCS file.
71 For example, `a/RCS/b/c' is now an RCS file with an empty extension.
72 Formerly, `RCS' had to be the last directory in the pathname.
74 rlog's -d option by default now uses exclusive time ranges.
75 E.g. `rlog -d"<T"' now excludes revisions whose times equal T exactly.
76 Use `rlog -d"<=T"' to get the old behavior.
78 merge now takes up to three -L options, one for each input file.
79 Formerly, it took at most two -L options, for the 1st and 3rd input files.
81 `rcs' now requires at least one option; this is for future expansion.
83 Other features new to RCS version 5.7 include:
85 merge and rcsmerge now pass -A, -E, and -e options to the subsidiary diff3.
87 rcs -kb acts like rcs -ko, except it uses binary I/O on working files.
88 This makes no difference under Posix or Unix, but it does matter elsewhere.
89 With -kb in effect, rcsmerge refuses to merge;
90 this avoids common problems with CVS merging.
92 The following is for future use by GNU Emacs 19's version control package:
94 rcs's new -M option causes it to not send mail when you break somebody
95 else's lock. This is not meant for casual use; see rcs(1).
97 ci's new -i option causes an error if the RCS file already exists.
98 Similarly, -j causes an error if the RCS file does not already exist.
100 The new keyword `Name' is supported; its value is the name, if any,
101 used to check out the revision. E.g. `co -rN foo' causes foo's
102 $Name...$ keyword strings to end in `: N $'.
104 The new -zZONE option causes RCS to output dates and times using ISO 8601
105 format with ZONE as the time zone, and to use ZONE as the default time
106 zone for input. Its most common use is the -zLT option, which causes RCS
107 to use local time externally. You can also specify foreign time zones;
108 e.g. -z+05:30 causes RCS to use India time (5 hours 30 minutes east of UTC).
109 This option does not affect RCS files themselves, which always use UTC;
110 it affects only output (e.g. rlog output, keyword expansion, diff -c times)
111 and interpretation of options (e.g. the -d option of ci, co, and rlog).
112 Bare -z restores the default behavior of UTC with no time zone indication,
113 and the traditional RCS date separator `/' instead of the ISO 8601 `-'.
114 RCSINIT may contain a -z option. ci -k parses UTC offsets.
116 The new -T option of ci, co, rcs, and rcsclean preserves the modification
117 time of the RCS file unless a revision is added or removed.
118 ci -T sets the RCS file's modification time to the new revision's time
119 if the former precedes the latter and there is a new revision;
120 otherwise, it preserves the RCS file's modification time.
121 Use this option with care, as it can confuse `make'; see ci(1).
123 The new -N option of rlog omits symbolic names from the output.
125 A revision number that starts with `.' is considered to be relative to
126 the default branch (normally the trunk). A branch number followed by `.'
127 stands for the last revision on that branch.
129 If someone else already holds the lock, rcs -l now asks whether you want
130 to break it, instead of immediately reporting an error.
132 ci now always unlocks a revision like 3.5 if you check in a revision
133 like 3.5.2.1 that is the first of a new branch of that revision.
134 Formerly it was inconsistent.
136 File names may now contain tab, newline, space, and '$'.
137 They are represented in keyword strings with \t, \n, \040, and \044.
138 \ in a file name is now represented by \\ in a keyword string.
140 Identifiers may now start with a digit and (unless they are symbolic names)
141 may contain `.'. This permits author names like `john.doe' and `4tran'.
143 A bare -V option now prints the current version number.
145 rcsdiff outputs more readable context diff headers if diff -L works.
147 rcsdiff -rN -rN now suppresses needless checkout and comparison
148 of identical revisions.
150 Error messages now contain the names of files to which they apply.
152 Mach style memory mapping is now supported.
154 The installation procedure now conforms to the GNU coding standards.
156 When properly configured, RCS now strictly conforms to Posix 1003.1b-1993.
159 Features new to RCS version 5.6 include:
161 Security holes have been plugged; setgid use is no longer supported.
163 co can retrieve old revisions much more efficiently.
164 To generate the Nth youngest revision on the trunk,
165 the old method used up to N passes through copies of the working file;
166 the new method uses a piece table to generate the working file in one pass.
168 When ci finds no changes in the working file,
169 it automatically reverts to the previous revision unless -f is given.
171 RCS follows symbolic links to RCS files instead of breaking them,
172 and warns when it breaks hard links to RCS files.
174 `$' stands for the revision number taken from working file keyword strings.
175 E.g. if F contains an Id keyword string,
176 `rcsdiff -r$ F' compares F to its checked-in revision, and
177 `rcs -nL:$ F' gives the symbolic name L to F's revision.
179 co and ci's new -M option sets the modification time
180 of the working file to be that of the revision.
181 Without -M, ci now tries to avoid changing the working file's
182 modification time if its contents are unchanged.
184 rcs's new -m option changes the log message of an old revision.
186 RCS is portable to hosts that do not permit `,' in filenames.
187 (`,' is not part of the Posix portable filename character set.)
188 A new -x option specifies extensions other than `,v' for RCS files.
189 The Unix default is `-x,v/', so that the working file `w' corresponds
190 to the first file in the list `RCS/w,v', `w,v', `RCS/w' that works.
191 The non-Unix default is `-x', so that only `RCS/w' is tried.
192 Eventually, the Unix default should change to `-x/,v'
193 to encourage interoperability among all Posix hosts.
195 A new RCSINIT environment variable specifies defaults for options like -x.
197 The separator for revision ranges has been changed from `-' to `:', because
198 the range `A-B' is ambiguous if `A', `B' and `A-B' are all symbolic names.
199 E.g. the old `rlog -r1.5-1.7' is now `rlog -r1.5:1.7'; ditto for `rcs -o'.
200 For a while RCS will still support (but warn about) the old `-' separator.
202 RCS manipulates its lock files using a method that is more reliable under NFS.
205 Features new to RCS version 5 include:
207 RCS can check in arbitrary files, not just text files, if diff -a works.
208 RCS can merge lines containing just a single `.' if diff3 -m works.
209 GNU diff supports the -a and -m options.
211 RCS can now be used as a setuid program.
212 See ci(1) for how users can employ setuid copies of ci, co, and rcsclean.
213 Setuid privileges yield extra security if the effective user owns RCS files
214 and directories, and if only the effective user can write RCS directories.
215 RCS uses the real user for all accesses other than writing RCS directories.
216 As described in ci(1), there are three levels of setuid support.
218 1. Setuid works fully if the seteuid() system call lets any
219 process switch back and forth between real and effective users,
220 as specified in Posix 1003.1a Draft 5.
222 2. On hosts with saved setuids (a Posix 1003.1-1990 option) and without
223 a modern seteuid(), setuid works unless the real or effective user is root.
225 3. On hosts that lack both modern seteuid() and saved setuids,
226 setuid does not work, and RCS uses the effective user for all accesses;
227 formerly it was inconsistent.
229 New options to co, rcsdiff, and rcsmerge give more flexibility to keyword
232 -kkv substitutes the default `$Keyword: value $' for keyword strings.
233 However, a locker's name is inserted only as a file is being locked,
234 i.e. by `ci -l' and `co -l'. This is normally the default.
236 -kkvl acts like -kkv, except that a locker's name is always inserted
237 if the given revision is currently locked. This was the default in
238 version 4. It is now the default only with when using rcsdiff to
239 compare a revision to a working file whose mode is that of a file
240 checked out for changes.
242 -kk substitutes just `$Keyword$', which helps to ignore keyword values
243 when comparing revisions.
245 -ko retrieves the old revision's keyword string, thus bypassing keyword
248 -kv retrieves just `value'. This can ease the use of keyword values, but
249 it is dangerous because it causes RCS to lose track of where the keywords
250 are, so for safety the owner write permission of the working file is
251 turned off when -kv is used; to edit the file later, check it out again
254 rcs -ko sets the default keyword substitution to be in the style of co -ko,
255 and similarly for the other -k options. This can be useful with file
256 formats that cannot tolerate changing the lengths of keyword strings.
257 However it also renders a RCS file readable only by RCS version 5 or later.
258 Use rcs -kkv to restore the usual default substitution.
260 RCS can now be used by development groups that span time zone boundaries.
261 All times are now displayed in UTC, and UTC is the default time zone.
262 To use local time with co -d, append ` LT' to the time.
263 When interchanging RCS files with sites running older versions of RCS,
264 time stamp discrepancies may prevent checkins; to work around this,
265 use `ci -d' with a time slightly in the future.
267 Dates are now displayed using four-digit years, not two-digit years.
268 Years given in -d options must now have four digits.
269 This change is required for RCS to continue to work after 1999/12/31.
270 The form of dates in version 5 RCS files will not change until 2000/01/01,
271 so in the meantime RCS files can still be interchanged with sites
272 running older versions of RCS. To make room for the longer dates,
273 rlog now outputs `lines: +A -D' instead of `lines added/del: A/D'.
275 To help prevent diff programs that are broken or have run out of memory
276 from trashing an RCS file, ci now checks diff output more carefully.
278 ci -k now handles the Log keyword, so that checking in a file
279 with -k does not normally alter the file's contents.
281 RCS no longer outputs white space at the ends of lines
282 unless the original working file had it.
283 For consistency with other keywords,
284 a space, not a tab, is now output after `$Log:'.
285 Rlog now puts lockers and symbolic names on separate lines in the output
286 to avoid generating lines that are too long.
287 A similar fix has been made to lists in the RCS files themselves.
289 RCS no longer outputs the string `Locker: ' when expanding Header or Id
290 keywords. This saves space and reverts back to version 3 behavior.
292 The default branch is not put into the RCS file unless it is nonempty.
293 Therefore, files generated by RCS version 5 can be read by RCS version 3
294 unless they use the default branch feature introduced in version 4.
295 This fixes a compatibility problem introduced by version 4.
297 RCS can now emulate older versions of RCS; see `co -V'.
298 This may be useful to overcome compatibility problems
299 due to the above changes.
301 Programs like Emacs can now interact with RCS commands via a pipe:
302 the new -I option causes ci, co, and rcs to run interactively,
303 even if standard input is not a terminal.
304 These commands now accept multiple inputs from stdin separated by `.' lines.
306 ci now silently ignores the -t option if the RCS file already exists.
307 This simplifies some shell scripts and improves security in setuid sites.
309 Descriptive text may be given directly in an argument of the form -t-string.
311 The character set for symbolic names has been upgraded
312 from Ascii to ISO 8859.
314 rcsdiff now passes through all options used by GNU diff;
315 this is a longer list than 4.3BSD diff.
317 merge's new -L option gives tags for merge's overlap report lines.
318 This ability used to be present in a different, undocumented form;
319 the new form is chosen for compatibility with GNU diff3's -L option.
321 rcsmerge and merge now have a -q option, just like their siblings do.
323 rcsclean's new -n option outputs what rcsclean would do,
324 without actually doing it.
326 RCS now attempts to ignore parts of an RCS file that look like they come
327 from a future version of RCS.
329 When properly configured, RCS now strictly conforms with Posix 1003.1-1990.
330 RCS can still be compiled in non-Posix traditional Unix environments,
331 and can use common BSD and USG extensions to Posix.
332 RCS is a conforming Standard C program, and also compiles under traditional C.
334 Arbitrary limits on internal table sizes have been removed.
335 The only limit now is the amount of memory available via malloc().
337 File temporaries, lock files, signals, and system call return codes
338 are now handled more cleanly, portably, and quickly.
339 Some race conditions have been removed.
341 A new compile-time option RCSPREFIX lets administrators avoid absolute path
342 names for subsidiary programs, trading speed for flexibility.
344 The configuration procedure is now more automatic.
346 Snooping has been removed.
349 Version 4 was the first version distributed by FSF.
350 Beside bug fixes, features new to RCS version 4 include:
352 The notion of default branch has been added; see rcs -b.
355 Version 3 was included in the 4.3BSD distribution.
358 Here are some possible future changes for RCS:
360 Bring back sccstorcs.
362 Add an option to `rcsmerge' so that it can use an arbitrary program
363 to do the 3-way merge, instead of the default `merge'.
364 Likewise for `rcsdiff' and `diff'. It should be possible to pass
365 arbitrary options to these programs, and to the subsidiary `co's.
367 Add format options for finer control over the output of ident and rlog.
368 E.g. there should be an easy way for rlog to output lines like
369 `src/main.c 2.4 wft', one for each locked revision.
370 rlog options should have three orthogonal types: selecting files,
371 selecting revisions, and selecting rlog format.
373 Add format options for finer control over the output of keyword strings.
374 E.g. there should be some way to prepend @(#), and there should be some
375 way to change $ to some other character to disable further substitution.
376 These options should make the resulting files uneditable, like -kv.
378 Add long options, e.g. `--version'. Unfortunately RCS's option syntax
379 is incompatible with getopt. Perhaps the best way is to overload `rcs', e.g.
380 `rcs diff --keyword-substitution=old file' instead of `rcsdiff -ko file'.
382 Add a way to put only the interesting part of the path into the $Header
385 rlog -rM:N should work even if M and N have different numbers of fields,
386 so long as M is an ancestor of N or vice versa.
388 rcs should evaluate options in order; this allows rcs -oS -nS.
390 rcs should be able to fix minor mistakes in checkin dates and authors.
392 Be able to redo your most recent checkin with minor changes.
394 co -u shouldn't complain about a writable working file if it won't change
397 Configure the Makefile automatically, as well as conf.h.
399 Add a new option to rcs that behaves like -o, but that doesn't lose the
400 nonempty log messages, but instead merges them with the next revision
401 if it exists, perhaps with a 1-line header containing author, date, etc.
403 Add a `-' option to take the list of pathnames from standard input.
404 Perhaps the pathnames should be null-terminated, not newline-terminated,
405 so that pathnames that contain newlines are handled properly.
407 Permit multiple option-pathname pairs, e.g. co -r1.4 a -r1.5 b.
409 Add options to allow arbitrary combinations of working file names
410 with RCS file names -- they shouldn't have to match.
412 Add an option to break a symbolic link to an RCS file,
413 instead of breaking the hard link that it points to.
415 Add ways to specify the earliest revision, the most recent revision,
416 the earliest or latest revision on a particular branch, and
417 the parent or child of some other revision.
419 If a user has multiple locks, perhaps ci should fall back on ci -k's
420 method to figure out which revision to use.
422 Symbolic names need not refer to existing branches and revisions.
423 rcs(1)'s BUGS section says this is a bug. Is it? If so, it should be fixed.
425 Add an option to rcs -o so that old log messages are not deleted if
426 the next undeleted revision exists, but are merely appended to the log
427 message of that revision.
429 ci -k should be able to get keyword values from the first `$Log' entry.
431 Add an option to rcsclean to clean directories recursively.
433 Write an rcsck program that repairs corrupted RCS files,
434 much as fsck repairs corrupted file systems.
435 For example, it should remove stale lock files.
437 Clean up the source code with a consistent indenting style.
439 Update the date parser to use the more modern getdate.y by Bellovin,
440 Salz, and Berets, or the even more modern getdate by Moraes. None of
441 these getdate implementations are as robust as RCS's old warhorse in
442 avoiding problems like arithmetic overflow, so they'll have to be
445 Break up the code into a library so that it's easier to write new programs
446 that manipulate RCS files, and so that useless code is removed from the
447 existing programs. For example, the rcs command contains unnecessary
448 keyword substitution baggage, and the merge command can be greatly pruned.
450 Make it easier to use your favorite text editor to edit log messages,
451 etc. instead of having to type them in irretrievably at the terminal.
453 Let the user specify a search path for default branches,
454 e.g. to use L as the default branch if it works, and M otherwise.
455 Let the user require that at least one entry in the default branch path works.
456 Let the user say that later entries in the default branch path are read only,
457 i.e. one cannot check in changes to them.
458 This should be an option settable by RCSINIT.
460 Add a way for a user to see which revisions affected which lines.
462 Have `rlog -nN F' print just the revision number that N translates to.
463 E.g. `rlog -nB. F' would print the highest revision on the branch B.
464 Use this to add an option -bB to rcsbranch, to freeze the named branch.
465 This should interact well with default branches.
467 Add a co option that prints the revision number before each line,
468 as SCCS's `get -m' does.
470 The following projects require a change to RCS file format.
472 Allow keyword expansion to be changed on a per-revision basis,
473 not on a per-file basis as now. This would allow -ko to be used
474 on imported revisions, with the default -kkv otherwise.
476 When two or more branches are merged, record all the ancestors
477 of the new revision. The hard part of this is keeping track of all
478 the ancestors of a working file while it's checked out.
480 Add loose locking, which is like non-strict but applies to all users,
481 not just the owner of the RCS file.
483 Be able to store RCS files in compressed format.
484 Don't bother to use a .Z extension that would exceed file name length limits;
485 just look at the magic number.
487 Add locker commentary, e.g. `co -l -m"checkout to fix merge bug" foo'
488 to tell others why you checked out `foo'.
489 Also record the time when the revision was locked,
490 and perhaps the working pathname (if applicable).
492 Let the user mark an RCS revision as deleted; checking out such a revision
493 would result in no working file. Similarly, using `co -d' with a date either
494 before the initial revision or after the file was marked deleted should
495 remove the working file. For extra credit, extend the notion of `deleted' to
496 include `renamed'. RCS should support arbitrary combinations of renaming and
497 deletion, e.g. renaming A to B and B to A, checking in new revisions to both
498 files, and then renaming them back.
500 Be able to check in an entire directory structure into a single RCS file.
502 Use a better scheme for locking revisions; the current scheme requires
503 changing the RCS file just to lock or unlock a revision.
504 The new scheme should coexist as well as possible with older versions of RCS,
505 and should avoid the rare NFS bugs mentioned in rcsedit.c.
506 E.g. if there's a reliable lockd running, RCS should use it
507 instead of relying on NFS.
509 Add rcs options for changing keyword names, e.g. XConsortium instead of Id.
511 Add a `$Description' keyword; but this may be tricky, since descriptions can
512 contain newlines and $s.
514 Add a `$Copyright' keyword that expands to a copyright notice.
516 Add frozen branches a la SCCS. In general, be able to emulate all of
517 SCCS, so that an SCCS-to-RCS program can be practical. For example,
518 there should be an equivalent to the SCCS prt command.
520 Add support for distributed RCS, where widely separated
521 users cannot easily access each others' RCS files,
522 and must periodically distribute and reconcile new revisions.
524 Be able to create empty branches.
526 Be able to store just deltas from a read-only principal copy,
527 e.g. from source on CD-ROM.
529 Improve RCS's method for storing binary files.
530 Although it is more efficient than SCCS's,
531 the diff algorithm is still line oriented,
532 and often generates long output for minor changes to an executable file.
534 From the user's point of view, it would be best if
535 RCS detected and handled binary files without human intervention,
536 switching expansion methods as needed from revision to revision.
538 Allow RCS to determine automagically whether -ko or -kb should be the default
539 by inspecting the file's contents or name. The magic should be optional
540 and user-programmable.
542 Extend the grammar of RCS files so that keywords need not be in a fixed order.
544 Internationalize messages; unfortunately, there's no common standard yet.
545 This requires a change in RCS file format because of the
546 `empty log message' and `checked in with -k' hacks inside RCS files.
548 Add documentation in texinfo format.