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   1GNU Emacs NEWS -- history of user-visible changes.  17-Aug-1988
   2
   3Copyright (C) 1988, 2006-2012  Free Software Foundation, Inc.
   4See the end of the file for license conditions.
   5
   6
   7This file is about changes in emacs version 18.
   8
   9
  10
  11Changes in version 18.52.
  12
  13* X windows version 10 is supported under system V.
  14
  15* Pop-up menus are now supported with the same Lisp interface in
  16both version 10 and 11 of X windows.
  17
  18* C-x 4 a is a new command to edit a change-log entry in another window.
  19
  20* The emacs client program now allows an option +NNN to specify the
  21line number to go to in the file whose name follows.  Thus,
  22    emacsclient foo.c +45 bar.c
  23will find the files `foo.c' and `bar.c', going to line 45 in `bar.c'.
  24
  25* Dired allows empty directories to be deleted like files.
  26
  27* When the terminal type is used to find a terminal-specific file to
  28run, Emacs now tries the entire terminal type first.  If that doesn't
  29yield a file that exists, the last hyphen and what follows it is
  30stripped.  If that doesn't yield a file that exists, the previous
  31hyphen is stripped, and so on until all hyphens are gone.  For
  32example, if the terminal type is `aaa-48-foo', Emacs will try first
  33`term/aaa-48-foo.el', then `term/aaa-48.el' and finally `term/aaa.el'.
  34
  35Underscores now receive the same treatment as hyphens.
  36
  37* Texinfo features: @defun, etc.  texinfo-show-structure.
  38New template commands.  texinfo-format-region.
  39
  40* The special "local variable" `eval' is now ignored if you are running
  41as root.
  42
  43* New command `c-macro-expand' shows the result of C macro expansion
  44in the region.  It works using the C preprocessor, so its results
  45are completely accurate.
  46
  47* Errors in trying to auto save now flash error messages for a few seconds.
  48
  49* Killing a buffer now sends SIGHUP to the buffer's process.
  50
  51* New hooks.
  52
  53** `spell-region' now allows you to filter the text before spelling-checking.
  54If the value of `spell-filter' is non-nil, it is called, with no arguments,
  55looking at a temporary buffer containing a copy of the text to be checked.
  56It can alter the text freely before the spell program sees it.
  57
  58** The variable `lpr-command' now specifies the command to be used when
  59you use the commands to print text (such as M-x print-buffer).
  60
  61** Posting netnews now calls the value of `news-inews-hook' (if not nil)
  62as a function of no arguments before the actual posting.
  63
  64** Rmail now calls the value of `rmail-show-message-hook' (if not nil)
  65as a function of no arguments, each time a new message is selected.
  66
  67** `kill-emacs' calls the value of `kill-emacs-hook' as a function of no args.
  68
  69* New libraries.
  70See the source code of each library for more information.
  71
  72** icon.el: a major mode for editing programs written in Icon.
  73
  74** life.el: a simulator for the cellular automaton "life".  Load the
  75library and run M-x life.
  76
  77** doctex.el: a library for converting the Emacs `etc/DOC' file of
  78documentation strings into TeX input.
  79
  80** saveconf.el: a library which records the arrangement of windows and
  81buffers when you exit Emacs, and automatically recreates the same
  82setup the next time you start Emacs.
  83
  84** uncompress.el: a library that automatically uncompresses files
  85when you visit them.
  86
  87** c-fill.el: a mode for editing filled comments in C.
  88
  89** kermit.el: an extended version of shell-mode designed for running kermit.
  90
  91** spook.el: a library for adding some "distract the NSA" keywords to every
  92message you send.
  93
  94** hideif.el: a library for hiding parts of a C program based on preprocessor
  95conditionals.
  96
  97** autoinsert.el: a library to put in some initial text when you visit
  98a nonexistent file.  The text used depends on the major mode, and
  99comes from a directory of files created by you.
 100
 101* New programming features.
 102
 103** The variable `window-system-version' now contains the version number
 104of the window system you are using (if appropriate).  When using X windows,
 105its value is either 10 or 11.
 106
 107** (interactive "N") uses the prefix argument if any; otherwise, it reads
 108a number using the minibuffer.
 109
 110** VMS: there are two new functions `vms-system-info' and `shrink-to-icon'.
 111The former allows you to get many kinds of system status information.
 112See its self-documentation for full details.
 113The second is used with the window system: it iconifies the Emacs window.
 114
 115** VMS: the new function `define-logical-name' allows you to create
 116job-wide logical names.  The old function `define-dcl-symbol' has been
 117removed.
 118
 119
 120
 121Changes in version 18.50.
 122
 123* X windows version 11 is supported.
 124
 125Define X11 in config.h if you want X version 11 instead of version 10.
 126
 127* The command M-x gdb runs the GDB debugger as an inferior.
 128It asks for the filename of the executable you want to debug.
 129
 130GDB runs as an inferior with I/O through an Emacs buffer.  All the
 131facilities of Shell mode are available.  In addition, each time your
 132program stops, and each time you select a new stack frame, the source
 133code is displayed in another window with an arrow added to the line
 134where the program is executing.
 135
 136Special GDB-mode commands include M-s, M-n, M-i, M-u, M-d, and C-c C-f
 137which send the GDB commands `step', `next', `stepi', `up', `down'
 138and `finish'.
 139
 140In any source file, the commands C-x SPC tells GDB to set a breakpoint
 141on the current line.
 142
 143* M-x calendar displays a three-month calendar.
 144
 145* C-u 0 C-x C-s never makes a backup file.
 146
 147This is a way you can explicitly request not to make a backup.
 148
 149* `term-setup-hook' is for users only.
 150
 151Emacs never uses this variable for internal purposes, so you can freely
 152set it in your `.emacs' file to make Emacs do something special after
 153loading any terminal-specific setup file from `lisp/term'.
 154
 155* `copy-keymap' now copies recursive submaps.
 156
 157* New overlay-arrow feature.
 158
 159If you set the variable `overlay-arrow-string' to a string
 160and `overlay-arrow-position' to a marker, that string is displayed on
 161the screen at the position of that marker, hiding whatever text would
 162have appeared there.  If that position isn't on the screen, or if
 163the buffer the marker points into isn't displayed, there is no effect.
 164
 165* -batch mode can read from the terminal.
 166
 167It now works to use `read-char' to do terminal input in a noninteractive
 168Emacs run.  End of file causes Emacs to exit.
 169
 170* Variables `data-bytes-used' and `data-bytes-free' removed.
 171
 172These variables cannot really work because the 24-bit range of an
 173integer in (most ports of) GNU Emacs is not large enough to hold their
 174values on many systems.
 175
 176
 177
 178Changes in version 18.45, since version 18.41.
 179
 180* C indentation parameter `c-continued-brace-offset'.
 181
 182This parameter's value is added to the indentation of any
 183line that is in a continuation context and starts with an open-brace.
 184For example, it applies to the open brace shown here:
 185
 186     if (x)
 187       {
 188
 189The default value is zero.
 190
 191* Dabbrev expansion (Meta-/) preserves case.
 192
 193When you use Meta-/ to search the buffer for an expansion of an
 194abbreviation, if the expansion found is all lower case except perhaps
 195for its first letter, then the case pattern of the abbreviation
 196is carried over to the expansion that replaces it.
 197
 198* TeX-mode syntax.
 199
 200\ is no longer given "escape character" syntax in TeX mode.  It now
 201has the syntax of an ordinary punctuation character.  As a result,
 202\[...\] and such like are considered to balance each other.
 203
 204* Mail-mode automatic Reply-to field.
 205
 206If the variable `mail-default-reply-to' is non-`nil', then each time
 207you start to compose a message, a Reply-to field is inserted with
 208its contents taken from the value of `mail-default-reply-to'.
 209
 210* Where is your .emacs file?
 211
 212If you run Emacs under `su', so your real and effective uids are
 213different, Emacs uses the home directory associated with the real uid
 214(the name you actually logged in under) to find the .emacs file.
 215
 216Otherwise, Emacs uses the environment variable HOME to find the .emacs
 217file.
 218
 219The .emacs file is not loaded at all if -batch is specified.
 220
 221* Prolog mode is the default for ".pl" files.
 222
 223* File names are not case-sensitive on VMS.
 224
 225On VMS systems, all file names that you specify are converted to upper
 226case.  You can use either upper or lower case indiscriminately.
 227
 228* VMS-only function 'define-dcl-symbol'.
 229
 230This is a new name for the function formerly called
 231`define-logical-name'.
 232
 233
 234
 235Editing Changes in Emacs 18
 236
 237* Additional systems and machines are supported.
 238
 239GNU Emacs now runs on Vax VMS.  However, many facilities that are normally
 240implemented by running subprocesses do not work yet.  This includes listing
 241a directory and sending mail.  There are features for running subprocesses
 242but they are incompatible with those on Unix.  I hope that some of
 243the VMS users can reimplement these features for VMS (compatibly for
 244the user, if possible).
 245
 246VMS wizards are also asked to work on making the subprocess facilities
 247more upward compatible with those on Unix, and also to rewrite their
 248internals to use the same Lisp objects that are used on Unix to
 249represent processes.
 250
 251In addition, the TI Nu machine running Unix system V, the AT&T 3b, and
 252the Wicat, Masscomp, Integrated Solutions, Alliant, Amdahl uts, Mips,
 253Altos 3068 and Gould Unix systems are now supported.  The IBM PC-RT is
 254supported under 4.2, but not yet under system V.  The GEC 93 is close
 255to working.  The port for the Elxsi is partly merged.  See the file
 256MACHINES for full status information and machine-specific installation
 257advice.
 258
 259* Searching is faster.
 260
 261Forward search for a text string, or for a regexp that is equivalent
 262to a text string, is now several times faster.  Motion by lines and
 263counting lines is also faster.
 264
 265* Memory usage improvements.
 266
 267It is no longer possible to run out of memory during garbage
 268collection.  As a result, running out of memory is never fatal.  This
 269is due to a new garbage collection algorithm which compactifies
 270strings in place rather than copying them.  Another consequence of the
 271change is a reduction in total memory usage and a slight increase in
 272garbage collection speed.
 273
 274* Display changes.
 275
 276** Editing above top of screen.
 277
 278When you delete or kill or alter text that reaches to the top of the
 279screen or above it, so that display would start in the middle of a
 280line, Emacs will usually attempt to scroll the text so that display
 281starts at the beginning of a line again.
 282
 283** Yanking in the minibuffer.
 284
 285The message "Mark Set" is no longer printed when the minibuffer is
 286active.  This is convenient with many commands, including C-y, that
 287normally print such a message.
 288
 289** Cursor appears in last line during y-or-n questions.
 290
 291Questions that want a `y' or `n' answer now move the cursor
 292to the last line, following the question.
 293
 294* Library loading changes.
 295
 296`load' now considers all possible suffixes (`.elc', `.el' and none)
 297for each directory in `load-path' before going on to the next directory.
 298It now accepts an optional fourth argument which, if non-nil, says to
 299use no suffixes; then the file name must be given in full.  The search
 300of the directories in `load-path' goes on as usual in this case, but
 301it too can be prevented by passing an absolute file name.
 302
 303The value of `load-path' no longer by default includes nil (meaning to
 304look in the current default directory).  The idea is that `load' should
 305be used to search the path only for libraries to be found in the standard
 306places.  If you want to override system libraries with your own, place
 307your own libraries in one special directory and add that directory to the
 308front of `load-path'.
 309
 310The function `load' is no longer a command; that is to say, `M-x load'
 311is no longer allowed.  Instead, there are two commands for loading files.
 312`M-x load-library' is equivalent to the old meaning of `M-x load'.
 313`M-x load-file' reads a file name with completion and defaulting
 314and then loads exactly that file, with no searching and no suffixes.
 315
 316* Emulation of other editors.
 317
 318** `edt-emulation-on' starts emulating DEC's EDT editor.
 319
 320Do `edt-emulation-off' to return Emacs to normal.
 321
 322** `vi-mode' and `vip-mode' starts emulating vi.
 323
 324These are two different vi emulations provided by GNU Emacs users.
 325We are interested in feedback as to which emulation is preferable.
 326
 327See the documentation and source code for these functions
 328for more information.
 329
 330** `set-gosmacs-bindings' emulates Gosling Emacs.
 331
 332This command changes many global bindings to resemble those of
 333Gosling Emacs.  The previous bindings are saved and can be restored using
 334`set-gnu-bindings'.
 335
 336* Emulation of a display terminal.
 337
 338Within Emacs it is now possible to run programs (such as emacs or
 339supdup) which expect to do output to a visual display terminal.
 340
 341See the function `terminal-emulator' for more information.
 342
 343* New support for keypads and function keys.
 344
 345There is now a first attempt at terminal-independent support for
 346keypad and function keys.
 347
 348Emacs now defines a standard set of key-names for function and keypad
 349keys, and provides standard hooks for defining them.  Most of the
 350standard key-names have default definitions built into Emacs; you can
 351override these in a terminal-independent manner.  The default definitions
 352and the conventions for redefining them are in the file `lisp/keypad.el'.
 353
 354These keys on the terminal normally work by sending sequences of
 355characters starting with ESC.  The exact sequences used vary from
 356terminal to terminal.  Emacs interprets them in two stages:
 357in the first stage, terminal-dependent sequences are mapped into
 358the standard key-names; then second stage maps the standard key-names
 359into their definitions in a terminal-independent fashion.
 360
 361The terminal-specific file `term/$TERM.el' now is responsible only for
 362establishing the mapping from the terminal's escape sequences into
 363standard key-names.  It no longer knows what Emacs commands are
 364assigned to the standard key-names.
 365
 366One other change in terminal-specific files: if the value of the TERM
 367variable contains a hyphen, only the part before the first hyphen is
 368used in forming the name of the terminal-specific file.  Thus, for
 369terminal type `aaa-48', the file loaded is now `term/aaa.el' rather
 370than `term/aaa-48.el'.
 371
 372* New startup command line options.
 373
 374`-i FILE' or `-insert FILE' in the command line to Emacs tells Emacs to
 375insert the contents of FILE into the current buffer at that point in
 376command line processing.  This is like using the command M-x insert-file.
 377
 378`-funcall', `-load', `-user' and `-no-init-file' are new synonyms for
 379`-f', `-l', `-u' and `-q'.
 380
 381`-nw' means don't use a window system.  If you are using a terminal
 382emulator on the X window system and you want to run Emacs to work through
 383the terminal emulator instead of working directly with the window system,
 384use this switch.
 385
 386* Buffer-sorting commands.
 387
 388Various M-x commands whose names start with `sort-' sort parts of
 389the region:
 390
 391sort-lines	divides the region into lines and sorts them alphabetically.
 392sort-pages	divides into pages and sorts them alphabetically.
 393sort-paragraphs	divides into paragraphs and sorts them alphabetically.
 394sort-fields	divides into lines and sorts them alphabetically
 395		according to one field in the line.
 396		The numeric argument specifies which field (counting
 397		from field 1 at the beginning of the line).  Fields in a line
 398		are separated by whitespace.
 399sort-numeric-fields
 400		is similar but converts the specified fields to numbers
 401		and sorts them numerically.
 402sort-columns	divides into lines and sorts them according to the contents
 403		of a specified range of columns.
 404
 405Refer to the self-documentation of these commands for full usage information.
 406
 407* Changes in various commands.
 408
 409** `tags-query-replace' and `tags-search' change.
 410
 411These functions now display the name of the file being searched at the moment.
 412
 413** `occur' output now serves as a menu.  `occur-menu' command deleted.
 414
 415`M-x occur' now allows you to move quickly to any of the occurrences
 416listed.  Select the `*Occur*' buffer that contains the output of `occur',
 417move point to the occurrence you want, and type C-c C-c.
 418This will move point to the same occurrence in the buffer that the
 419occurrences were found in.
 420
 421The command `occur-menu' is thus obsolete, and has been deleted.
 422
 423One way to get a list of matching lines without line numbers is to
 424copy the text to another buffer and use the command `keep-lines'.
 425
 426** Incremental search changes.
 427
 428Ordinary and regexp incremental searches now have distinct default
 429search strings.  Thus, regexp searches recall only previous regexp
 430searches.
 431
 432If you exit an incremental search when the search string is empty,
 433the old default search string is kept.  The default does not become
 434empty.
 435
 436Reversing the direction of an incremental search with C-s or C-r
 437when the search string is empty now does not get the default search
 438string.  It leaves the search string empty.  A second C-s or C-r
 439will get the default search string.  As a result, you can do a reverse
 440incremental regexp search with C-M-s C-r.
 441
 442If you add a `*', `?' or `\|' to an incremental search regexp,
 443point will back up if that is appropriate.  For example, if
 444you have searched for `ab' and add a `*', point moves to the
 445first match for `ab*', which may be before the match for `ab'
 446that was previously found.
 447
 448If an incremental search is failing and you ask to repeat it,
 449it will start again from the beginning of the buffer (or the end,
 450if it is a backward search).
 451
 452The search-controlling parameters `isearch-slow-speed' and
 453`isearch-slow-window-lines' have now been renamed to start with
 454`search' instead of `isearch'.  Now all the parameters' names start
 455with `search'.
 456
 457If `search-slow-window-lines' is negative, the slow search window
 458is put at the top of the screen, and the absolute value or the
 459negative number specifies the height of it.
 460
 461** Undo changes
 462
 463The undo command now will mark the buffer as unmodified only when it is
 464identical to the contents of the visited file.
 465
 466** C-M-v in minibuffer.
 467
 468If while in the minibuffer you request help in a way that uses a
 469window to display something, then until you exit the minibuffer C-M-v
 470in the minibuffer window scrolls the window of help.
 471
 472For example, if you request a list of possible completions, C-M-v can
 473be used reliably to scroll the completion list.
 474
 475** M-TAB command.
 476
 477Meta-TAB performs completion on the Emacs Lisp symbol names.  The sexp
 478in the buffer before point is compared against all existing nontrivial
 479Lisp symbols and completed as far as is uniquely determined by them.
 480Nontrivial symbols are those with either function definitions, values
 481or properties.
 482
 483If there are multiple possibilities for the very next character, a
 484list of possible completions is displayed.
 485
 486** Dynamic abbreviation package.
 487
 488The new command Meta-/ expands an abbreviation in the buffer before point
 489by searching the buffer for words that start with the abbreviation.
 490
 491** Changes in saving kbd macros.
 492
 493The commands `write-kbd-macro' and `append-kbd-macro' have been
 494deleted.  The way to save a keyboard macro is to use the new command
 495`insert-kbd-macro', which inserts Lisp code to define the macro as
 496it is currently defined into the buffer before point.  Visit a Lisp
 497file such as your Emacs init file `~/.emacs', insert the macro
 498definition (perhaps deleting an old definition for the same macro)
 499and then save the file.
 500
 501** C-x ' command.
 502
 503The new command C-x ' (expand-abbrev) expands the word before point as
 504an abbrev, even if abbrev-mode is not turned on.
 505
 506** Sending to inferior Lisp.
 507
 508The command C-M-x in Lisp mode, which sends the current defun to
 509an inferior Lisp process, now works by writing the text into a temporary
 510file and actually sending only a `load'-form to load the file.
 511As a result, it avoids the Unix bugs that used to strike when the
 512text was above a certain length.
 513
 514With a prefix argument, this command now makes the inferior Lisp buffer
 515appear on the screen and scrolls it so that the bottom is showing.
 516
 517Two variables `inferior-lisp-load-command' and `inferior-lisp-prompt',
 518exist to customize these feature for different Lisp implementations.
 519
 520** C-x p now disabled.
 521
 522The command C-x p, a nonrecommended command which narrows to the current
 523page, is now initially disabled like C-x n.
 524
 525* Dealing with files.
 526
 527** C-x C-v generalized
 528
 529This command is now allowed even if the current buffer is not visiting
 530a file.  As usual, it kills the current buffer and replaces it with a
 531newly found file.
 532
 533** M-x recover-file improved; auto save file names changed.
 534
 535M-x recover-file now checks whether the last auto-save file is more
 536recent than the real visited file before offering to read in the
 537auto-save file.  If the auto-save file is newer, a directory listing
 538containing the two files is displayed while you are asked whether you
 539want the auto save file.
 540
 541Visiting a file also makes this check.  If the auto-save file is more recent,
 542a message is printed suggesting that you consider using M-x recover file.
 543
 544Auto save file names now by default have a `#' at the end as well
 545as at the beginning.  This is so that `*.c' in a shell command
 546will never match auto save files.
 547
 548On VMS, auto save file names are made by appending `_$' at the front
 549and `$' at the end.
 550
 551When you change the visited file name of a buffer, the auto save file
 552is now renamed to belong to the new visited file name.
 553
 554You can customize the way auto save file names are made by redefining
 555the two functions `make-auto-save-file-name' and `auto-save-file-name-p',
 556both of which are defined in `files.el'.
 557
 558** Modifying a buffer whose file is changed on disk is detected instantly.
 559
 560On systems where clash detection (locking of files being edited) is
 561implemented, Emacs also checks the first time you modify a buffer
 562whether the file has changed on disk since it was last visited or saved.
 563If it has, you are asked to confirm that you want to change the buffer.
 564
 565** Exiting Emacs offers to save `*mail*'.
 566
 567Emacs can now know about buffers that it should offer to save on exit
 568even though they are not visiting files.  This is done for any buffer
 569which has a non-nil local value of `buffer-offer-save'.  By default,
 570Mail mode provides such a local value.
 571
 572** Backup file changes.
 573
 574If a backup file cannot be written in the directory of the visited file
 575due to fascist file protection, a backup file is now written in your home
 576directory as `~/%backup%~'.  Only one such file is made, ever, so only
 577the most recently made such backup is available.
 578
 579When backup files are made by copying, the last-modification time of the
 580original file is now preserved in the backup copy.
 581
 582** Visiting remote files.
 583
 584On an internet host, you can now visit and save files on any other
 585internet host directly from Emacs with the commands M-x ftp-find-file
 586and M-x ftp-write-file.  Specify an argument of the form HOST:FILENAME.
 587Since standard internet FTP is used, the other host may be any kind
 588of machine and is not required to have any special facilities.
 589
 590The first time any one remote host is accessed, you will be asked to
 591give the user name and password for use on that host.  FTP is reinvoked
 592each time you ask to use it, but previously specified user names and
 593passwords are remembered automatically.
 594
 595** Dired `g' command.
 596
 597`g' in Dired mode is equivalent to M-x revert-buffer; it causes the
 598current contents of the same directory to be read in.
 599
 600* Changes in major modes.
 601
 602** C mode indentation change.
 603
 604The binding of Linefeed is no longer changed by C mode.  It once again
 605has its normal meaning, which is to insert a newline and then indent
 606afterward.
 607
 608The old definition did one additional thing: it reindented the line
 609before the new newline.  This has been removed because it made the
 610command twice as slow.  The only time it was really useful was after the
 611insertion of an `else', since the fact of starting with `else' may change
 612the way that line is indented.  Now you will have to type TAB again
 613yourself to reindent the `else' properly.
 614
 615If the variable `c-tab-always-indent' is set to `nil', the TAB command
 616in C mode, with no argument, will just insert a tab character if there
 617is non-whitespace preceding point on the current line.  Giving it a
 618prefix argument will force reindentation of the line (as well as
 619of the compound statement that begins after point, if any).
 620
 621** Fortran mode now exists.
 622
 623This mode provides commands for motion and indentation of Fortran code,
 624plus built-in abbrevs for Fortran keywords.  For details, see the manual
 625or the on-line documentation of the command `fortran-mode'.
 626
 627** Scribe mode now exists.
 628
 629This mode does something useful for editing files of Scribe input.
 630It is used automatically for files with names ending in ".mss".
 631
 632** Modula2 and Prolog modes now exist.
 633
 634These modes are for editing programs in the languages of the same names.
 635They can be selected with M-x modula-2-mode and M-x prolog-mode.
 636
 637** Telnet mode changes.
 638
 639The telnet mode special commands have now been assigned to C-c keys.
 640Most of them are the same as in Shell mode.
 641
 642** Picture mode changes.
 643
 644The special picture-mode commands to specify the direction of cursor
 645motion after insertion have been moved to C-c keys.  The commands to
 646specify diagonal motion were already C-c keys; they are unchanged.
 647The keys to specify horizontal or vertical motion are now
 648C-c < (left), C-c > (right), C-c ^ (up) and C-c . (down).
 649
 650** Nroff mode comments.
 651
 652Comments are now supported in Nroff mode.  The standard comment commands
 653such as M-; and C-x ; know how to insert, align and delete comments
 654that start with backslash-doublequote.
 655
 656** LaTeX mode.
 657
 658LaTeX mode now exists.  Use M-x latex-mode to select this mode, and
 659M-x plain-tex-mode to select the previously existing mode for Plain
 660TeX.  M-x tex-mode attempts to examine the contents of the buffer and
 661choose between latex-mode and plain-tex-mode accordingly; if the
 662buffer is empty or it cannot tell, the variable `TeX-default-mode'
 663controls the choice.  Its value should be the symbol for the mode to
 664be used.
 665
 666The facilities for running TeX on all or part of the buffer
 667work with LaTeX as well.
 668
 669Some new commands available in both modes:
 670
 671C-c C-l		recenter the window showing the TeX output buffer
 672		 so most recent line of output can be seen.
 673C-c C-k		kill the TeX subprocess.
 674C-c C-q		show the printer queue.
 675C-c C-f		close a block (appropriate for LaTeX only).
 676		 If the current line contains a \begin{...},
 677		 this inserts an \end{...} on the following line
 678		 and puts point on a blank line between them.
 679
 680** Outline mode changes.
 681
 682Invisible lines in outline mode are now indicated by `...' at the
 683end of the previous visible line.
 684
 685The special outline heading motion commands are now all on C-c keys.
 686A few new ones have been added.  Here is a full list:
 687
 688C-c C-n   Move to next visible heading (formerly M-})
 689C-c C-p   Move to previous visible heading (formerly M-{)
 690C-c C-f   Move to next visible heading at the same level.
 691	   Thus, if point is on a level-2 heading line,
 692	   this command moves to the next visible level-2 heading.
 693C-c C-b   Move to previous visible heading at the same level.
 694C-c C-u   Move up to previous visible heading at a higher level.
 695
 696The variable `outline-regexp' now controls recognition of heading lines.
 697Any line whose beginning matches this regexp is a heading line.
 698The depth in outline structure is determined by the length of
 699the string that matches.
 700
 701A line starting with a ^L (formfeed) is now by default considered
 702a header line.
 703
 704* Mail reading and sending.
 705
 706** MH-E changes.
 707
 708MH-E has been extensively modified and improved since the v17 release.
 709It contains many new features, including commands to: extracted failed
 710messages, kill a draft message, undo changes to a mail folder, monitor
 711delivery of a letter, print multiple messages, page digests backwards,
 712insert signatures, and burst digests.  Also, many commands have been
 713made to able to deal with named sequences of messages, instead of
 714single messages.  MH-E also has had numerous bugs fixed and commands
 715made to run faster.  Furthermore, its keybindings have been changed to
 716be compatible with Rmail and the rest of GNU Emacs.
 717
 718** Mail mode changes.
 719
 720The C-c commands of mail mode have been rearranged:
 721
 722C-c s, C-c c, C-c t and C-c b (move point to various header fields)
 723have been reassigned as C-c C-f C-s, C-c C-f C-c, C-c C-f C-t and C-c
 724C-f C-b.  C-c C-f is for "field".
 725
 726C-c y, C-c w and C-c q have been changed to C-c C-y, C-c C-w and C-c C-q.
 727
 728Thus, C-c LETTER is always unassigned.
 729
 730** Rmail C-r command changed to w.
 731
 732The Rmail command to edit the current message is now `w'.  This change
 733has been made because people frequently type C-r while in Rmail hoping
 734to do a reverse incremental search.  That now works.
 735
 736* Rnews changes.
 737
 738** Caesar rotation added.
 739
 740The function news-caesar-buffer-body performs encryption and
 741decryption of the body of a news message.  It defaults to the USENET
 742standard of 13, and accepts any numeric arg between 1 to 25 and -25 to -1.
 743The function is bound to C-c C-r in both news-mode and news-reply-mode.
 744
 745** rmail-output command added.
 746
 747The C-o command has been bound to rmail-output in news-mode.
 748This allows one to append an article to a file which is in either Unix
 749mail or RMAIL format.
 750
 751** news-reply-mode changes.
 752
 753The C-c commands of news reply mode have been rearranged and changed,
 754so that C-c LETTER is always unassigned:
 755
 756C-c y, C-c w and C-c q have been changed to C-c C-y, C-c C-w and C-c C-q.
 757
 758C-c c, C-c t, and C-c b (move to various mail header fields) have been
 759deleted (they make no sense for posting and replying to USENET).
 760
 761C-c s (move to Subject: header field) has been reassigned as C-c C-f
 762C-s.  C-c C-f is for "field".  Several additional move to news header
 763field commands have been added.
 764
 765The local news-reply-mode bindings now look like this:
 766
 767C-c C-s  news-inews (post the message)    C-c C-c  news-inews
 768C-c C-f	 move to a header field (and create it if there isn't):
 769	 C-c C-f C-n  move to Newsgroups:	C-c C-f C-s  move to Subj:
 770	 C-c C-f C-f  move to Followup-To:      C-c C-f C-k  move to Keywords:
 771	 C-c C-f C-d  move to Distribution:	C-c C-f C-a  move to Summary:
 772C-c C-y  news-reply-yank-original (insert current message, in NEWS).
 773C-c C-q  mail-fill-yanked-message (fill what was yanked).
 774C-c C-r  caesar rotate all letters by 13 places in the article's body (rot13).
 775
 776* Existing Emacs usable as a server.
 777
 778Programs such as mailers that invoke "the editor" as an inferior
 779to edit some text can now be told to use an existing Emacs process
 780instead of creating a new editor.
 781
 782To do this, you must have an Emacs process running and capable of
 783doing terminal I/O at the time you want to invoke it.  This means that
 784either you are using a window system and give Emacs a separate window
 785or you run the other programs as inferiors of Emacs (such as, using
 786M-x shell).
 787
 788First prepare the existing Emacs process by loading the `server'
 789library and executing M-x server-start.  (Your .emacs can do this
 790automatically.)
 791
 792Now tell the other programs to use, as "the editor", the Emacs client
 793program (etc/emacsclient, located in the same directory as this file).
 794This can be done by setting the environment variable EDITOR.
 795
 796When another program invokes the emacsclient as "the editor", the
 797client actually transfers the file names to be edited to the existing
 798Emacs, which automatically visits the files.
 799
 800When you are done editing a buffer for a client, do C-x # (server-edit).
 801This marks that buffer as done, and selects the next buffer that the client
 802asked for.  When all the buffers requested by a client are marked in this
 803way, Emacs tells the client program to exit, so that the program that
 804invoked "the editor" will resume execution.
 805
 806You can only have one server Emacs at a time, but multiple client programs
 807can put in requests at the same time.
 808
 809The client/server work only on Berkeley Unix, since they use the Berkeley
 810sockets mechanism for their communication.
 811
 812
 813Changes in Lisp programming in Emacs version 18.
 814
 815* Init file changes.
 816
 817** Suffixes no longer accepted on `.emacs'.
 818
 819Emacs will no longer load a file named `.emacs.el' or `emacs.elc'
 820in place of `.emacs'.  This is so that it will take less time to
 821find `.emacs'.  If you want to compile your init file, give it another
 822name and make `.emacs' a link to the `.elc' file, or make it contain
 823a call to `load' to load the `.elc' file.
 824
 825** `default-profile' renamed to `default', and loaded after `.emacs'.
 826
 827It used to be the case that the file `default-profile' was loaded if
 828and only if `.emacs' was not found.
 829
 830Now the name `default-profile' is not used at all.  Instead, a library
 831named `default' is loaded after the `.emacs' file.  `default' is loaded
 832whether the `.emacs' file exists or not.  However, loading of `default'
 833can be prevented if the `.emacs' file sets `inhibit-default-init' to non-nil.
 834
 835In fact, you would call the default file `default.el' and probably would
 836byte-compile it to speed execution.
 837
 838Note that for most purposes you are better off using a `site-init' library
 839since that will be loaded before the runnable Emacs is dumped.  By using
 840a `site-init' library, you avoid taking up time each time Emacs is started.
 841
 842** inhibit-command-line has been eliminated.
 843
 844This variable used to exist for .emacs files to set.  It has been
 845eliminated because you can get the same effect by setting
 846command-line-args to nil and setting inhibit-startup-message to t.
 847
 848* `apply' is more general.
 849
 850`apply' now accepts any number of arguments.  The first one is a function;
 851the rest are individual arguments to pass to that function, except for the
 852last, which is a list of arguments to pass.
 853
 854Previously, `apply' required exactly two arguments.  Its old behavior
 855follows as a special case of the new definition.
 856
 857* New code-letter for `interactive'.
 858
 859(interactive "NFoo: ") is like (interactive "nFoo: ") in reading
 860a number using the minibuffer to serve as the argument; however,
 861if a prefix argument was specified, it uses the prefix argument
 862value as the argument, and does not use the minibuffer at all.
 863
 864This is used by the `goto-line' and `goto-char' commands.
 865
 866* Semantics of variables.
 867
 868** Built-in per-buffer variables improved.
 869
 870Several built-in variables which in the past had a different value in
 871each buffer now behave exactly as if `make-variable-buffer-local' had
 872been done to them.
 873
 874These variables are `tab-width', `ctl-arrow', `truncate-lines',
 875`fill-column', `left-margin', `mode-line-format', `abbrev-mode',
 876`overwrite-mode', `case-fold-search', `auto-fill-hook',
 877`selective-display', `selective-display-ellipses'.
 878
 879To be precise, each variable has a default value which shows through
 880in most buffers and can be accessed with `default-value' and set with
 881`set-default'.  Setting the variable with `setq' makes the variable
 882local to the current buffer.  Changing the default value has retroactive
 883effect on all buffers in which the variable is not local.
 884
 885The variables `default-case-fold-search', etc., are now obsolete.
 886They now refer to the default value of the variable, which is not
 887quite the same behavior as before, but it should enable old init files
 888to continue to work.
 889
 890** New per-buffer variables.
 891
 892The variables `fill-prefix', `comment-column' and `indent-tabs-mode'
 893are now per-buffer.  They work just like `fill-column', etc.
 894
 895** New function `setq-default'.
 896
 897`setq-default' sets the default value of a variable, and uses the
 898same syntax that `setq' accepts: the variable name is not evaluated
 899and need not be quoted.
 900
 901`(setq-default case-fold-search nil)' would make searches case-sensitive
 902in all buffers that do not have local values for `case-fold-search'.
 903
 904** Functions `global-set' and `global-value' deleted.
 905
 906These functions were never used except by mistake by users expecting
 907the functionality of `set-default' and `default-value'.
 908
 909* Changes in defaulting of major modes.
 910
 911When `default-major-mode' is `nil', new buffers are supposed to
 912get their major mode from the buffer that is current.  However,
 913certain major modes (such as Dired mode, Rmail mode, Rmail Summary mode,
 914and others) are not reasonable to use in this way.
 915
 916Now such modes' names have been given non-`nil' `mode-class' properties.
 917If the current buffer's mode has such a property, Fundamental mode is
 918used as the default for newly created buffers.
 919
 920* `where-is-internal' requires additional arguments.
 921
 922This function now accepts three arguments, two of them required:
 923DEFINITION, the definition to search for; LOCAL-KEYMAP, the keymap
 924to use as the local map when doing the searching, and FIRST-ONLY,
 925which is nonzero to return only the first key found.
 926
 927This function returns a list of keys (strings) whose definitions
 928(in the LOCAL-KEYMAP or the current global map) are DEFINITION.
 929
 930If FIRST-ONLY is non-nil, it returns a single key (string).
 931
 932This function has changed incompatibly in that now two arguments
 933are required when previously only one argument was allowed.  To get
 934the old behavior of this function, write `(current-local-map)' as
 935the expression for the second argument.
 936
 937The incompatibility is sad, but `nil' is a legitimate value for the
 938second argument (it means there is no local keymap), so it cannot also
 939serve as a default meaning to use the current local keymap.
 940
 941* Abbrevs with hooks.
 942
 943When an abbrev defined with a hook is expanded, it now performs the
 944usual replacement of the abbrev with the expansion before running the
 945hook.  Previously the abbrev itself was deleted but the expansion was
 946not inserted.
 947
 948* Function `scan-buffer' deleted.
 949
 950Use `search-forward' or `search-backward' in place of `scan-buffer'.
 951You will have to rearrange the arguments.
 952
 953* X window interface improvements.
 954
 955** Detect release of mouse buttons.
 956
 957Button-up events can now be detected.  See the file `lisp/x-mouse.el'
 958for details.
 959
 960** New pop-up menu facility.
 961
 962The new function `x-popup-menu' pops up a menu (in a X window)
 963and returns an indication of which selection the user made.
 964For more information, see its self-documentation.
 965
 966* M-x disassemble.
 967
 968This command prints the disassembly of a byte-compiled Emacs Lisp function.
 969
 970Would anyone like to interface this to the debugger?
 971
 972* `insert-buffer-substring' can insert part of the current buffer.
 973
 974The old restriction that the text being inserted had to come from
 975a different buffer is now lifted.
 976
 977When inserting text from the current buffer, the text to be inserted
 978is determined from the specified bounds before any copying takes place.
 979
 980* New function `substitute-key-definition'.
 981
 982This is a new way to replace one command with another command as the
 983binding of whatever keys may happen to refer to it.
 984
 985(substitute-key-definition OLDDEF NEWDEF KEYMAP) looks through KEYMAP
 986for keys defined to run OLDDEF, and rebinds those keys to run NEWDEF
 987instead.
 988
 989* New function `insert-char'.
 990
 991Insert a specified character, a specified number of times.
 992
 993* `mark-marker' changed.
 994
 995When there is no mark, this now returns a marker that points
 996nowhere, rather than `nil'.
 997
 998* `ding' accepts argument.
 999
1000When given an argument, the function `ding' does not terminate
1001execution of a keyboard macro.  Normally, `ding' does terminate
1002all macros that are currently executing.
1003
1004* New function `minibuffer-depth'.
1005
1006This function returns the current depth in minibuffer activations.
1007The value is zero when the minibuffer is not in use.
1008Values greater than one are possible if the user has entered the
1009minibuffer recursively.
1010
1011* New function `documentation-property'.
1012
1013(documentation-property SYMBOL PROPNAME) is like (get SYMBOL PROPNAME),
1014except that if the property value is a number `documentation-property'
1015will take that number (or its absolute value) as a character position
1016in the DOC file and return the string found there.
1017
1018(documentation-property VAR 'variable-documentation) is the proper
1019way for a Lisp program to get the documentation of variable VAR.
1020
1021* New documentation-string expansion feature.
1022
1023If a documentation string (for a variable or function) contains text
1024of the form `\<FOO>', it means that all command names specified in
1025`\[COMMAND]' construct from that point on should be turned into keys
1026using the value of the variable FOO as the local keymap.  Thus, for example,
1027
1028  `\<emacs-lisp-mode-map>\[eval-defun] evaluates the defun containing point.'
1029
1030will expand into
1031
1032  "ESC C-x evaluates the defun containing point."
1033
1034regardless of the current major mode, because ESC C-x is defined to
1035run `eval-defun' in the keymap `emacs-lisp-mode-map'.  The effect is
1036to show the key for `eval-defun' in Emacs Lisp mode regardless of the
1037current major mode.
1038
1039The `\<...>' construct applies to all `\[...]' constructs that follow it,
1040up to the end of the documentation string or the next `\<...>'.
1041
1042Without `\<...>', the keys for commands specified in `\[...]' are found
1043in the current buffer's local map.
1044
1045The current global keymap is always searched second, whether `\<...>'
1046has been used or not.
1047
1048* Multiple hooks allowed in certain contexts.
1049
1050The old hook variables `find-file-hook', `find-file-not-found-hook' and
1051`write-file-hook' have been replaced.
1052
1053The replacements are `find-file-hooks', `find-file-not-found-hooks'
1054and `write-file-hooks'.  Each holds a list of functions to be called;
1055by default, `nil', for no functions.  The functions are called in
1056order of appearance in the list.
1057
1058In the case of `find-file-hooks', all the functions are executed.
1059
1060In the case of `find-file-not-found-hooks', if any of the functions
1061returns non-`nil', the rest of the functions are not called.
1062
1063In the case of `write-file-hooks', if any of the functions returns
1064non-`nil', the rest of the functions are not called, and the file is
1065considered to have been written already; so actual writing in the
1066usual way is not done.  If `write-file-hooks' is local to a buffer,
1067it is set to its global value if `set-visited-file-name' is called
1068(and thus by C-x C-w as well).
1069
1070`find-file-not-found-hooks' and `write-file-hooks' can be used
1071together to implement editing of files that are not stored as Unix
1072files: stored in archives, or inside version control systems, or on
1073other machines running other operating systems and accessible via ftp.
1074
1075* New hooks for suspending Emacs.
1076
1077Suspending Emacs runs the hook `suspend-hook' before suspending
1078and the hook `suspend-resume-hook' if the suspended Emacs is resumed.
1079Running a hook is done by applying the variable's value to no arguments
1080if the variable has a non-`nil' value.  If `suspend-hook' returns
1081non-`nil', then suspending is inhibited and so is running the
1082`suspend-resume-hook'.  The non-`nil' value means that the `suspend-hook'
1083has done whatever suspending is required.
1084
1085* Disabling commands can print a special message.
1086
1087A command is disabled by giving it a non-`nil' `disabled' property.
1088Now, if this property is a string, it is included in the message
1089printed when the user tries to run the command.
1090
1091* Emacs can open TCP connections.
1092
1093The function `open-network-stream' opens a TCP connection to
1094a specified host and service.  Its value is a Lisp object that represents
1095the connection.  The object is a kind of "subprocess", and I/O are
1096done like I/O to subprocesses.
1097
1098* Display-related changes.
1099
1100** New mode-line control features.
1101
1102The display of the mode line used to be controlled by a format-string
1103that was the value of the variable `mode-line-format'.
1104
1105This variable still exists, but it now allows more general values,
1106not just strings.  Lists, cons cells and symbols are also meaningful.
1107
1108The mode line contents are created by outputting various mode elements
1109one after the other.  Here are the kinds of objects that can be
1110used as mode elements, and what they do in the display:
1111
1112  string        the contents of the string are output to the mode line,
1113		and %-constructs are replaced by other text.
1114
1115  t or nil	ignored; no output results.
1116
1117  symbol	the symbol's value is used.  If the value is a string,
1118		the string is output verbatim to the mode line
1119		(so %-constructs are not interpreted).  Otherwise,
1120		the symbol's value is processed as a mode element.
1121
1122  list (whose first element is a string or list or cons cell)
1123		the elements of the list are treated as as mode elements,
1124		so that the output they generate is concatenated,
1125
1126  list (whose car is a symbol)
1127		if the symbol's value is non-nil, the second element of the
1128		list is treated as a mode element.  Otherwise, the third
1129		element (if any) of the list is treated as a mode element.
1130
1131  cons (whose car is a positive integer)
1132		the cdr of the cons is used as a mode element, but
1133		the text it produces is padded, if necessary, to have
1134		at least the width specified by the integer.
1135
1136  cons (whose car is a negative integer)
1137		the cdr of the cons is used as a mode element, but
1138		the text it produces is truncated, if necessary, to have
1139		at most the width specified by the integer.
1140
1141There is always one mode element to start with, that being the value of
1142`mode-line-format', but if this value is a list then it leads to several
1143more mode elements, which can lead to more, and so on.
1144
1145There is one new %-construct for mode elements that are strings:
1146`%n' displays ` Narrow' for a buffer that is narrowed.
1147
1148The default value of `mode-line-format' refers to several other variables.
1149These variables are `mode-name', `mode-line-buffer-identification',
1150`mode-line-process', `mode-line-modified', `global-mode-string' and
1151`minor-mode-alist'.  The first four are local in every buffer in which they
1152are changed from the default.
1153
1154mode-name	Name of buffer's major mode.  Local in every buffer.
1155
1156mode-line-buffer-identification
1157		Normally the list ("Emacs: %17b"), it is responsible
1158		for displaying text to indicate what buffer is being shown
1159		and what kind of editing it is doing.  `Emacs' means
1160		that a file of characters is being edited.  Major modes
1161		such as Info and Dired which edit or view other kinds
1162		of data often change this value.  This variables becomes
1163		local to the current buffer if it is setq'd.
1164
1165mode-line-process
1166		Normally nil, this variable is responsible for displaying
1167		information about the process running in the current buffer.
1168		M-x shell-mode and M-x compile alter this variable.
1169
1170mode-line-modified
1171		This variable is responsible for displaying the indication
1172		of whether the current buffer is modified or read-only.
1173		By default its value is `("--%*%*-")'.
1174
1175minor-mode-alist
1176		This variable is responsible for displaying text for those
1177		minor modes that are currently enabled.  Its value
1178		is a list of elements of the form (VARIABLE STRING),
1179		where STRING is to be displayed if VARIABLE's value
1180		(in the buffer whose mode line is being displayed)
1181		is non-nil.  This variable is not made local to particular
1182		buffers, but loading some libraries may add elements to it.
1183
1184global-mode-string
1185		This variable is used to display the time, if you ask
1186		for that.
1187
1188The idea of these variables is to eliminate the need for major modes
1189to alter mode-line-format itself.
1190
1191** `window-point' valid for selected window.
1192
1193The value returned by `window-point' used to be incorrect when its
1194argument was the selected window.  Now the value is correct.
1195
1196** Window configurations may be saved as Lisp objects.
1197
1198The function `current-window-configuration' returns a special type of
1199Lisp object that represents the current layout of windows: the
1200sizes and positions of windows, which buffers appear in them, and
1201which parts of the buffers appear on the screen.
1202
1203The function `set-window-configuration' takes one argument, which must
1204be a window configuration object, and restores that configuration.
1205
1206** New hook `temp-output-buffer-show-hook'.
1207
1208This hook allows you to control how help buffers are displayed.
1209Whenever `with-output-to-temp-buffer' has executed its body and wants
1210to display the temp buffer, if this variable is bound and non-`nil'
1211then its value is called with one argument, the temp buffer.
1212The hook function is solely responsible for displaying the buffer.
1213The standard manner of display--making the buffer appear in a window--is
1214used only if there is no hook function.
1215
1216** New function `minibuffer-window'.
1217
1218This function returns the window used (sometimes) for displaying
1219the minibuffer.  It can be used even when the minibuffer is not active.
1220
1221** New feature to `next-window'.
1222
1223If the optional second argument is neither `nil' nor `t', the minibuffer
1224window is omitted from consideration even when active; if the starting
1225window was the last non-minibuffer window, the value will be the first
1226non-minibuffer window.
1227
1228** New variable `minibuffer-scroll-window'.
1229
1230When this variable is non-`nil', the command `scroll-other-window'
1231uses it as the window to be scrolled.  Displays of completion-lists
1232set this variable to the window containing the display.
1233
1234** New argument to `sit-for'.
1235
1236A non-nil second argument to `sit-for' means do not redisplay;
1237just wait for the specified time or until input is available.
1238
1239** Deleted function `set-minor-mode'; minor modes must be changed.
1240
1241The function `set-minor-mode' has been eliminated.  The display
1242of minor mode names in the mode line is now controlled by the
1243variable `minor-mode-alist'.  To specify display of a new minor
1244mode, it is sufficient to add an element to this list.  Once that
1245is done, you can turn the mode on and off just by setting a variable,
1246and the display will show its status automatically.
1247
1248** New variable `cursor-in-echo-area'.
1249
1250If this variable is non-nil, the screen cursor appears on the
1251last line of the screen, at the end of the text displayed there.
1252
1253Binding this variable to t is useful at times when reading single
1254characters of input with `read-char'.
1255
1256** New per-buffer variable `selective-display-ellipses'.
1257
1258If this variable is non-nil, an ellipsis (`...') appears on the screen
1259at the end of each text line that is followed by invisible text.
1260
1261If this variable is nil, no ellipses appear.  Then there is no sign
1262on the screen that invisible text is present.
1263
1264Text is made invisible under the control of the variable
1265`selective-display'; this is how Outline mode and C-x $ work.
1266
1267** New variable `no-redraw-on-reenter'.
1268
1269If you set this variable non-nil, Emacs will not clear the screen when
1270you resume it after suspending it.  This is for the sake of terminals
1271with multiple screens of memory, where the termcap entry has been set
1272up to switch between screens when Emacs is suspended and resumed.
1273
1274** New argument to `set-screen-height' or `set-screen-width'.
1275
1276These functions now take an optional second argument which says
1277what significance the newly specified height or width has.
1278
1279If the argument is nil, or absent, it means that Emacs should
1280believe that the terminal height or width really is as just specified.
1281
1282If the argument is t, it means Emacs should not believe that the
1283terminal really is this high or wide, but it should use the
1284specific height or width as the number of lines or columns to display.
1285Thus, you could display only 24 lines on a screen known to have 48 lines.
1286
1287What practical difference is there between using only 24 lines for display
1288and really believing that the terminal has 24 lines?
1289
12901. The ``real'' height of the terminal says what the terminal command
1291to move the cursor to the last line will do.
1292
12932. The ``real'' height of the terminal determines how much padding is
1294needed.
1295
1296* File-related changes.
1297
1298** New parameter `backup-by-copying-when-mismatch'.
1299
1300If this variable is non-`nil', then when Emacs is about to save a
1301file, it will create the backup file by copying if that would avoid
1302changing the file's uid or gid.
1303
1304The default value of this variable is `nil', because usually it is
1305useful to have the uid of a file change according to who edited it
1306last.  I recommend that this variable be left normally `nil' and
1307changed with a local variables list in those particular files where
1308the uid needs to be preserved.
1309
1310** New parameter `file-precious-flag'.
1311
1312If this variable is non-`nil', saving the buffer tries to avoid
1313leaving an incomplete file due to disk full or other I/O errors.
1314It renames the old file before saving.  If saving is successful,
1315the renamed file is deleted; if saving gets an error, the renamed
1316file is renamed back to the name you visited.
1317
1318Backups are always made by copying for such files.
1319
1320** New variable `buffer-offer-save'.
1321
1322If the value of this variable is non-`nil' in a buffer then exiting
1323Emacs will offer to save the buffer (if it is modified and nonempty)
1324even if the buffer is not visiting a file.  This variable is
1325automatically made local to the current buffer whenever it is set.
1326
1327** `rename-file', `copy-file', `add-name-to-file' and `make-symbolic-link'.
1328
1329The third argument to these functions used to be `t' or `nil'; `t'
1330meaning go ahead even if the specified new file name already has a file,
1331and `nil' meaning to get an error.
1332
1333Now if the third argument is a number it means to ask the user for
1334confirmation in this case.
1335
1336** New optional argument to `copy-file'.
1337
1338If `copy-file' receives a non-nil fourth argument, it attempts
1339to give the new copy the same time-of-last-modification that the
1340original file has.
1341
1342** New function `file-newer-than-file-p'.
1343
1344(file-newer-than-file-p FILE1 FILE2) returns non-nil if FILE1 has been
1345modified more recently than FILE2.  If FILE1 does not exist, the value
1346is always nil; otherwise, if FILE2 does not exist, the value is t.
1347This is meant for use when FILE2 depends on FILE1, to see if changes
1348in FILE1 make it necessary to recompute FILE2 from it.
1349
1350** Changed function `file-exists-p'.
1351
1352This function is no longer the same as `file-readable-p'.
1353`file-exists-p' can now return t for a file that exists but which
1354the fascists won't allow you to read.
1355
1356** New function `file-locked-p'.
1357
1358This function receives a file name as argument and returns `nil'
1359if the file is not locked, `t' if locked by this Emacs, or a
1360string giving the name of the user who has locked it.
1361
1362** New function `file-name-sans-versions'.
1363
1364(file-name-sans-versions NAME) returns a substring of NAME, with any
1365version numbers or other backup suffixes deleted from the end.
1366
1367** New functions for directory names.
1368
1369Although a directory is really a kind of file, specifying a directory
1370uses a somewhat different syntax from specifying a file.
1371In Emacs, a directory name is used as part of a file name.
1372
1373On Unix, the difference is small: a directory name ends in a slash,
1374while a file name does not: thus, `/usr/rms/' to name a directory,
1375while `/usr/rms' names the file which holds that directory.
1376
1377On VMS, the difference is considerable: `du:[rms.foo]' specifies a
1378directory, but the name of the file that holds that directory is
1379`du:[rms]foo.dir'.
1380
1381There are two new functions for converting between directory names
1382and file names.  `directory-file-name' takes a directory name and
1383returns the name of the file in which that directory's data is stored.
1384`file-name-as-directory' takes the name of a file and returns
1385the corresponding directory name.  These always understand Unix file name
1386syntax; on VMS, they understand VMS syntax as well.
1387
1388For example, (file-name-as-directory "/usr/rms") returns "/usr/rms/"
1389and (directory-file-name "/usr/rms/") returns "/usr/rms".
1390On VMS, (file-name-as-directory "du:[rms]foo.dir") returns "du:[rms.foo]"
1391and (directory-file-name "du:[rms.foo]") returns "du:[rms]foo.dir".
1392
1393** Value of `file-attributes' changed.
1394
1395The function file-attributes returns a list containing many kinds of
1396information about a file.  Now the list has eleven elements.
1397
1398The tenth element is `t' if deleting the file and creating another
1399file of the same name would result in a change in the file's group;
1400`nil' if there would be no change.  You can also think of this as
1401comparing the file's group with the default group for files created in
1402the same directory by you.
1403
1404The eleventh element is the inode number of the file.
1405
1406** VMS-only function `file-name-all-versions'.
1407
1408This function returns a list of all the completions, including version
1409number, of a specified version-number-less file name.  This is like
1410`file-name-all-completions', except that the latter returns values
1411that do not include version numbers.
1412
1413** VMS-only variable `vms-stmlf-recfm'.
1414
1415On a VMS system, if this variable is non-nil, Emacs will give newly
1416created files the record format `stmlf'.  This is necessary for files
1417that must contain lines of arbitrary length, such as compiled Emacs
1418Lisp.
1419
1420When writing a new version of an existing file, Emacs always keeps
1421the same record format as the previous version; so this variable has
1422no effect.
1423
1424This variable has no effect on Unix systems.
1425
1426** `insert-file-contents' on an empty file.
1427
1428This no longer sets the buffer's "modified" flag.
1429
1430** New function (VMS only) `define-logical-name':
1431
1432(define-logical-name LOGICAL TRANSLATION) defines a VMS logical name
1433LOGICAL whose translation is TRANSLATION.  The new name applies to
1434the current process only.
1435
1436** Deleted variable `ask-about-buffer-names'.
1437
1438If you want buffer names for files to be generated in a special way,
1439you must redefine `create-file-buffer'.
1440
1441* Subprocess-related changes.
1442
1443** New function `process-list'.
1444
1445This function takes no arguments and returns a list of all
1446of Emacs's asynchronous subprocesses.
1447
1448** New function `process-exit-status'.
1449
1450This function, given a process, process name or buffer as argument,
1451returns the exit status code or signal number of the process.
1452If the process has not yet exited or died, this function returns 0.
1453
1454** Process output ignores `buffer-read-only'.
1455
1456Output from a process will go into the process's buffer even if the
1457buffer is read only.
1458
1459** Switching buffers in filter functions and sentinels.
1460
1461Emacs no longer saves and restore the current buffer around calling
1462the filter and sentinel functions, so these functions can now
1463permanently alter the selected buffer in a straightforward manner.
1464
1465** Specifying environment variables for subprocesses.
1466
1467When a subprocess is started with `start-process' or `call-process',
1468the value of the variable `process-environment' is taken to
1469specify the environment variables to give the subprocess.  The
1470value should be a list of strings, each of the form "VAR=VALUE".
1471
1472`process-environment' is initialized when Emacs starts up
1473based on Emacs's environment.
1474
1475** New variable `process-connection-type'.
1476
1477If this variable is `nil', when a subprocess is created, Emacs uses
1478a pipe rather than a pty to communicate with it.  Normally this
1479variable is `t', telling Emacs to use a pty if ptys are supported
1480and one is available.
1481
1482** New function `waiting-for-user-input-p'.
1483
1484This function, given a subprocess as argument, returns `t' if that
1485subprocess appears to be waiting for input sent from Emacs,
1486or `nil' otherwise.
1487
1488** New hook `shell-set-directory-error-hook'.
1489
1490The value of this variable is called, with no arguments, whenever
1491Shell mode gets an error trying to keep track of directory-setting
1492commands (such as `cd' and `pushd') used in the shell buffer.
1493
1494* New functions `user-uid' and `user-real-uid'.
1495
1496These functions take no arguments and return, respectively,
1497the effective uid and the real uid of the Emacs process.
1498The value in each case is an integer.
1499
1500* New variable `print-escape-newlines' controls string printing.
1501
1502If this variable is non-`nil', then when a Lisp string is printed
1503by the Lisp printing function `prin1' or `print', newline characters
1504are printed as `\n' rather than as a literal newline.
1505
1506* New function `sysnetunam' on HPUX.
1507
1508This function takes two arguments, a network address PATH and a
1509login string LOGIN, and executes the system call `netunam'.
1510It returns `t' if the call succeeds, otherwise `nil'.
1511
1512News regarding installation:
1513
1514* Many `s-...' file names changed.
1515
1516Many `s-...' files have been renamed.  All periods in such names,
1517except the ones just before the final `h', have been changed to
1518hyphens.  Thus, `s-bsd4.2.h' has been renamed to `s-bsd4-2.h'.
1519
1520This is so a Unix distribution can be moved mechanically to VMS.
1521
1522* `DOCSTR...' file now called `DOC-...'.
1523
1524The file of on-line documentation strings, that used to be
1525`DOCSTR.mm.nn.oo' in this directory, is now called `DOC-mm.nn.oo'.
1526This is so that it can port to VMS using the standard conventions
1527for translating filenames for VMS.
1528
1529This file also now contains the doc strings for variables as
1530well as functions.
1531
1532* Emacs no longer uses floating point arithmetic.
1533
1534This may make it easier to port to some machines.
1535
1536* Macros `XPNTR' and `XSETPNTR'; flag `DATA_SEG_BITS'.
1537
1538These macros exclusively are used to unpack a pointer from a Lisp_Object
1539and to insert a pointer into a Lisp_Object.  Redefining them may help
1540port Emacs to machines in which all pointers to data objects have
1541certain high bits set.
1542
1543If `DATA_SEG_BITS' is defined, it should be a number which contains
1544the high bits to be inclusive or'ed with pointers that are unpacked.
1545
1546* New flag `HAVE_X_MENU'.
1547
1548Define this flag in `config.h' in addition to `HAVE_X_WINDOWS'
1549to enable use of the Emacs interface to X Menus.  On some operating
1550systems, the rest of the X interface works properly but X Menus
1551do not work; hence this separate flag.  See the file `src/xmenu.c'
1552for more information.
1553
1554* Macros `ARRAY_MARK_FLAG' and `DONT_COPY_FLAG'.
1555
1556* `HAVE_ALLOCA' prevents assembly of `alloca.s'.
1557
1558* `SYSTEM_MALLOC' prevents use of GNU `malloc.c'.
1559
1560SYSTEM_MALLOC, if defined, means use the system's own `malloc' routines
1561rather than those that come with Emacs.
1562
1563Use this only if absolutely necessary, because if it is used you do
1564not get warnings when space is getting low.
1565
1566* New flags to control unexec.
1567
1568See the file `unexec.c' for a long comment on the compilation
1569switches that suffice to make it work on many machines.
1570
1571* `PNTR_COMPARISON_TYPE'
1572
1573Pointers that need to be compared for ordering are converted to this type
1574first.  Normally this is `unsigned int'.
1575
1576* `HAVE_VFORK', `HAVE_DUP2' and `HAVE_GETTIMEOFDAY'.
1577
1578These flags just say whether certain system calls are available.
1579
1580* New macros control compiler switches, linker switches and libraries.
1581
1582The m- and s- files can now control in a modular fashion the precise
1583arguments passed to `cc' and `ld'.
1584
1585LIBS_STANDARD defines the standard C libraries.  Default is `-lc'.
1586LIBS_DEBUG defines the extra libraries to use when debugging.  Default `-lg'.
1587LIBS_SYSTEM can be defined by the s- file to specify extra libraries.
1588LIBS_MACHINE can be defined by the m- file to specify extra libraries.
1589LIBS_TERMCAP defines the libraries for Termcap or Terminfo.
1590  It is defined by default in a complicated fashion but the m- or s- file
1591  can override it.
1592
1593LD_SWITCH_SYSTEM can be defined by the s- file to specify extra `ld' switches.
1594  The default is `-X' on BSD systems except those few that use COFF object files.
1595LD_SWITCH_MACHINE can be defined by the m- file to specify extra `ld' switches.
1596
1597C_DEBUG_SWITCH defines the switches to give `cc' when debugging.  Default `-g'.
1598C_OPTIMIZE_SWITCH defines the switches to give `cc' to optimize.  Default `-O'.
1599C_SWITCH_MACHINE can be defined by the m- file to specify extra `cc' switches.
1600
1601
1602
1603----------------------------------------------------------------------
1604This file is part of GNU Emacs.
1605
1606GNU Emacs is free software: you can redistribute it and/or modify
1607it under the terms of the GNU General Public License as published by
1608the Free Software Foundation, either version 3 of the License, or
1609(at your option) any later version.
1610
1611GNU Emacs is distributed in the hope that it will be useful,
1612but WITHOUT ANY WARRANTY; without even the implied warranty of
1613MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
1614GNU General Public License for more details.
1615
1616You should have received a copy of the GNU General Public License
1617along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
1618
1619
1620Local variables:
1621mode: text
1622end: