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GNU Emacs Frequently Asked Questions with Answers (part 2 of 2)

Sun May 12 23:47:35 1991


Building/Installing/Porting Emacs and Machine/OS-Specific Bugs:

50: Why do I get an "f68881_used undefined" error, when I build Emacs on my
 Sun 3?
  
  Barry A. Warsaw <warsaw@cme.nist.gov> writes:
  
  Some of the code that is being linked on the "ld" line of emacs'
  build command has been compiled with the -f68881 option.  Most
  common reason is that you're linking with X libraries which were
  built with -f68881 option set.  You need to either remove all
  dependencies to the 68881 (may mean a recompile of the X libraries
  with -fswitch or -fsoft option), or you need to link emacs with
  the 68881 startup file /usr/lib/Mcrt1.o.  Make this change to
  src/ymakefile:
  
	  change: #define START_FILES crt0.o
	  to:     #define START_FILES crt0.o /usr/lib/Mcrt1.o
  
  The order of these start files is critical.
  
51: How do I get Emacs running on VMS under DECwindows?
  
  Hal R. Brand <BRAND@addvax.llnl.gov> is said to have a VMS save set with
  a ready-to-run VMS version of Emacs for X Windows.  It is available via
  anonymous FTP (addvax.llnl.gov).
  
  Johan Vromans <jv@mh.nl> writes:
  
  Getting Emacs to run on VMS with DECwindows requires a number of changes
  to the sources. Fortunately this has been done already.  Joshua Marantz
  <josh@viewlogic.com> did most of the work for Emacs 18.52, and the mods
  were ported to 18.55 by Johan Vromans <jv@mh.nl>. Also included is the
  handling of DEC's LK201 keyboard.  You need to apply the changes to a
  fresh Emacs 18.55 distribution on a Unix system, and then you can copy
  the sources to VMS to perform the compile/link/build.
  
  The set of changes have been posted a number of times three times the
  last 12 months, so they should be widely available.
  
52: Why does Emacs ignore my X resources (my .Xdefaults file)?
  
  Try compiling Emacs with the XBACKWARDS macro defined.  There is a bug
  in some implementations of XGetDefault, which do not correspond to the
  documentation or the header files.
  
53: What should I do if I have trouble building Emacs?
  
  RMS writes:
  
  If you try to build Emacs and it does not run, the first thing to do is
  look in the file called PROBLEMS to see if a solution is given there.
  
  If none is given, then please send a report by mail to
  bug-gnu-emacs@prep.ai.mit.edu.  Please do not send it to
  help-gnu-emacs@prep.ai.mit.edu.
  
  Sending to help-gnu-emacs (which has the effect of posting on
  gnu.emacs.help) is undesirable because it takes the time of an
  unnecessarily large group of people, most of whom are just users and
  have no idea how to fix these problem.  bug-gnu-emacs reaches a much
  smaller group of people who are more likely to know what to do and have
  expressed a wish to receive more messages about Emacs than the others.
  


Weird/Confusing Problems:

54: Does Emacs have problems with files larger than 8 Megs?
  
  Most installed versions of GNU Emacs will use 24 bit signed integers
  (and 24 bit pointers!) internally.  This limits the file size that Emacs
  can handle to 8388608 bytes.
  
  Leonard N. Zubkoff <lnz@lucid.com> writes:
  
  Putting the following two lines in src/config.h before compiling Emacs
  allows for 26 bit integers and pointers:
  
    #define VALBITS 26
    #define GCTYPEBITS 5
  
  See question 55 for an explanation.
  
55: Why does Emacs use 24 bit integers and pointers?
  
  David Gillespie <daveg@csvax.cs.caltech.edu> writes:
  
  Emacs is largely written in a dialect of Lisp; Lisp is a freely-typed
  language in the sense that you can put any value of any type into any
  variable, or return it from a function, and so on.  So each value must
  carry a "tag" along with it identifying what kind of thing it is, e.g.,
  integer, pointer to a list, pointer to an editing buffer, and so on.
  Emacs uses standard 32-bit integers for data objects, taking the top 8
  bits for the tag and the bottom 24 bits for the value.  So integers (and
  pointers) are somewhat restricted compared to true C integers and
  pointers.
  
  Emacs uses 8-bit tags because that's a little faster on byte-oriented
  machines, but there are only really enough tags to require 6 bits.  See
  question 54 to find how to recompile Emacs with 6-bit tags and
  26-bit integers and pointers if space is at a premium for you.
  
56: Why does Emacs start up using the wrong directory?
  
  Most likely, you have an environment variable named PWD that is set to a
  value other than the name of your current directory.  This is most
  likely caused by using two different shell programs.  "ksh" and (some
  versions of) "csh" set and maintain the value of the PWD environment
  variable, but "sh" doesn't.  If you start sh from ksh, change your
  current directory inside sh, and then start Emacs from inside sh, PWD
  will have the wrong value but Emacs will use this value.  See the
  etc/OPTIONS file for more details.
  
  Perhaps an easier solution is not to use two shells.  The "chsh" program
  can often be used to change one's default login shell.
  
57: How do I edit a file with a "$" in its name?
  
  When entering a filename in the minibuffer, Emacs will attempt to expand
  a "$" followed by a word as an environment variable.  To suppress this
  behavior, type "$$" instead.
  
58: Why does Shell mode lose track of the shell's current directory?
  
  Emacs has no way of knowing when the shell actually changes its
  directory.  This is an intrinsic limitation of Unix.  So it tries to
  guess by recognizing "cd" commands.  If you type "cd" followed by a
  directory name with a variable reference ("cd $HOME/bin") or with a
  shell metacharacter ("cd ../lib*"), Emacs will fail to correctly guess
  the shell's new current directory.  A number of fixes and enhancements
  to Shell mode for this problem have been written, check the Emacs Lisp
  Archive (question 14).
  
59: Why doesn't Emacs expand my aliases when sending mail?
  
  First, you must separate multiple addresses with commas.
  
  Second, Emacs normally only reads the ".mailrc" file once per session,
  when you start to compose your first mail message.  If you edit .mailrc,
  you can type "M-ESC (build-mail-aliases) RET" to make Emacs reread
  .mailrc.
  
60: Why doesn't setting default-directory always work?
  
  There is a separate value of default-directory for each Emacs buffer.
  The value in the current buffer is the one that is used.
  
61: Why doesn't my change to load-path work?
  
  If you added file names with tildes (~) in them to your load-path,
  you'll need to do something like this:
  
    (setq load-path (mapcar 'expand-file-name load-path))
  
62: Why does the cursor always go to the wrong column when I move up or
 down one line?
  
  You have inadvertently typed "C-x C-n" (set-goal-column) which sets the
  "goal-column" to the column where the cursor was.  To undo this type
  "C-u C-x C-n".
  
  If you make this mistake frequently, you might want to unbind this
  command by doing one of these two:
  
    (define-key ctl-x-map "\C-n" nil)
    (put 'set-goal-column 'disabled t)
  
63: Why does Emacs hang with message "Unknown XMenu" with X11R4?
  
  Many different X errors can produce this message.  Here is the solution
  to one problem:
  
  X11 Release 4 now enforces some conditions in the X protocol that were
  previously allowed to pass unnoticed.  You need to put the X11R4 server
  into X11R3 bug compatibility mode for Emacs's Xmenu code to work.  You
  can do this with the command "xset bc".
  
64: Why doesn't display-time show the load average in the mode line anymore?
  
  In GNU Emacs 18.56, a change was made in the display-time code.
  Formerly, in version 18.55, Emacs used a program named "loadst" to
  notify Emacs of the change in time every minute.  loadst also sent Emacs
  the system load average if it was installed with sufficient privilege to
  get that information (or was on a system where no such privilege was
  needed).  Emacs then displayed this information in the mode line.
  
  In version 18.56, this code was changed to use a program named "wakeup".
  wakeup doesn't send Emacs any information, it's only purpose is to send
  Emacs *something* every minute, thus invoking the filter function in
  Emacs once a minute.  The filter function in Emacs does all the work of
  finding the time, date, and load average.  However, getting the load
  average requires the privilege to read kernel memory on most systems.
  Since giving Emacs this privilege would destroy any security a system
  might have, for almost everyone this is not an option.  In addition,
  Emacs does not have the code built into it to get this information on
  the systems which have special system calls for this purpose, even
  though loadst had code for this.
  
  The solution I use is to get the files lisp/display-time.el and
  etc/loadst.c from version 18.55 and use those with 18.57.  (I have heard
  a rumor that loadst disappeared because of the legal action Unipress
  threatened against IBM.)
  
  WARNING:  Do not install Emacs setgid kmem unless you wish to destroy
  any security your system might have!!!!!!!!!!
  
  If you are using Emacs 18.55 or earlier, or the solution I describe
  above, read further:
  
  The most likely cause of the problem is that "loadst" can't read the
  special file /dev/kmem.  To properly install loadst, it should be either
  setuid to the owner of /dev/kmem, or is should be setgid to the group to
  which /dev/kmem belongs.  In either case, /dev/kmem should be readable by
  its owner or its group, respectively.
  
  Another possibility is that your version of Unix doesn't have the load
  average data available in /dev/kmem.  Your version of Unix might have a
  special system call to retrieve this information (eg., inq_stats under
  UMAX), and loadst might not have been enhanced to cope with this.
  
65: Why doesn't GNUS work anymore via NNTP?
  
  There is a bug in NNTP version 1.5.10, such that when multiple requests
  are sent to the NNTP server, the server only handles the first one before
  blocking waiting for more input which never comes.  NNTP version 1.5.11
  claims to fix this.
  
  You can work around the bug inside Emacs like this:
  
    (setq nntp-maximum-request 1)
  
  I also have a patch for NNTP 1.5.10 that is based on the timeout code
  that was in 1.5.9.  However, please try to upgrade to 1.5.11 first.
  
66: Why does ispell sometimes ignore the local dictionary?
  
  You need to update the version of ispell to 2.0.02.  A patch is
  available via anonymous FTP
  (tut.cis.ohio-state.edu:/pub/gnu/ispell/patch2.Z).
  
  You also need to change a line in ispell.el from:
  
    (defconst ispell-version "2.0.01") ;; Check against output of "ispell -v".
  
  to:
  
    (defconst ispell-version "2.0.02") ;; Check against output of "ispell -v".
  
67: How do I get rid of the ^M junk in my Shell buffer?
  
  For tcsh, put this in your ".cshrc" (or ".tcshrc") file:
  
    if ($?EMACS) then
        if ($?tcsh) unset edit
        stty nl
    endif
  
  Or put this in your .emacs_tcsh file:
  
    unset edit
    stty nl
  
  Alternatively, use csh in your Shell buffers instead of tcsh.  One way
  is:
  
    (setq explicit-shell-file-name "/bin/csh") 
  
  and another is to do this in your .cshrc (or .tcshrc) file:
  
    setenv ESHELL /bin/csh
  
68: Does GNU Emacs have a vulnerability to Trojan horses?
  
  Yes.  Your site should put this in lisp/site-init.el before building
  Emacs:
  
    (setq inhibit-local-variables t)
  
  If Emacs has already been built, the expression should be put in
  lisp/default.el instead.
  
  The security hole that would otherwise be left open is described in the
  "File Variables" section of the manual (and Info tree).
  
69: How do I recover my mail files after RMAIL munges their format?
  
  You may have noticed that RMAIL has a disturbing way of eating your
  "mbox" file and producing instead an RMAIL file in an entirely different
  format.  To remedy this, Ken Manheimer <klm@cme.nist.gov> wrote a
  package called "rmail-to-vm" that does a very nice job of recovering
  mail files, even entire directories of mail files.
  
  WARNING:  The last version I used didn't correctly handle the number of
  spaces after the day of the month in the date portion of the "From "
  line message separator.  So you may have to add an extra space by hand
  after days with only one digit in them, or else Mail will think several
  messages are just one.
  


Configuring Emacs for yourself:

70: How do I set up a .emacs file properly?
  
  See the section of the manual on the .emacs file, inside the section on
  customization.  To reach this section of the online Info manual, type
  this:
  
    C-h i m emacs RET g init SPC file RET
  
  WARNING:  In general, new Emacs users should not have .emacs files,
  because it causes confusing non-standard behavior.  Then they send
  questions to help-gnu-emacs asking why Emacs isn't behaving as
  documented.  :-)
  
71: How do you debug a .emacs file?
  
  First start Emacs with the "-q" command line option.  Then, in the
  *scratch* buffer, type the following:
  
    (setq debug-on-error t) C-j
    (load-file "~/.emacs") C-j
  
  (C-j stands for Control-J, ie., hold the control key and press J.)
  
  If you have an error in your .emacs file, this will invoke the debugger
  when the error occurs.  If you don't know how to use the debugger do
  (setq stack-trace-on-error t) instead.
  
  WARNING: this will not discover errors caused by trying to do something
  that requires the terminal/window-system initialization code to have
  been loaded.  See question 37.
  
72: How do I turn on abbrevs by default just in mode XXX?
  
  Put this in your .emacs file:
  
    (condition-case ()
	(read-abbrev-file nil t)
      (file-error nil))
  
    (setq XXX-mode-hook
	  (function
	   (lambda ()
	     (setq abbrev-mode t))))
  
73: How do I turn on Auto-Fill mode by default?
  
  To turn on Auto-Fill mode just once for one buffer, you type "M-x
  auto-fill-mode".  To turn it on for every buffer in, for example, Text
  mode, do this:
  
    (setq text-mode-hook 'turn-on-auto-fill)
  
  If you want Auto-Fill mode on in all major modes, do this:
  
    (setq-default auto-fill-hook 'do-auto-fill)
  
74: How do I make Emacs use a certain major mode for certain files?
  
  If you want to use XXX mode for all files which end with the extension
  ".YYY", this will do it for you:
  
    (setq auto-mode-alist (cons '("\\.YYY\\'" . XXX-mode) auto-mode-alist))
  
  Otherwise put this somewhere in the first line of any file you want to
  edit in XXX mode:
  
    -*-XXX-*-
  
75: What are the valid X resource settings (ie., stuff in .Xdefaults file)?
  
  See the Emacs man page, or the etc/OPTIONS file.
  
76: How do I stop Emacs from beeping on a terminal?
  
  Martin R. Frank <martin@cc.gatech.edu> writes:
  
  Tell Emacs to use the 'visible bell' instead of the audible bell, and
  set the visible bell to nothing.
  
  Put this in your TERMCAP environment variable:
  
    ... :vb=: ...                       
  
  And evaluate this:
  
    (setq visible-bell t)
  
77: How do I turn down the bell volume in Emacs running under X Windows?
  
  Under Epoch you can do:
  
    (setq epoch::bell-volume 20)
  
  Under normal GNU Emacs you must modify the XTfeep function in
  src/x11term.c, and change the number 50 to -50:
  
    XTfeep ()
    {
	    BLOCK_INPUT_DECLARE ();
    #ifdef XDEBUG
	    fprintf (stderr, "XTfeep\n");
    #endif
	    BLOCK_INPUT ();
	    XBell (XXdisplay,50);	/* change this 50 to -50 */
	    UNBLOCK_INPUT ();
    }
  
  Then "xset b 0" will turn off Emacs's beeping.
  
  After "xset b BASE":
  
    XBell (disp,  VAL) beeps with volume BASE - (BASE*VAL)/100 + VAL,
    XBell (disp, -VAL) beeps with volume BASE - (BASE*VAL)/100.
  
78: How do I make Emacs send 8-bit characters to my terminal?
  
  Johan Widen <jw@sics.se> writes:
  
  A patch for emacs-18.55 is available by ftp and mail-server from
  sics.se.
  
  Anonymous FTP:
  site: sics.se [192.16.123.90]
  file: archive/emacs-18.55-8bit-diff
  
  E-mail:
  To: mail-server@sics.se
  body: send emacs-18.55-8bit-diff
  
79: How do I change load-path?
  
  In general, you should only *add* to the load-path.  You can add
  directory /XXX/YYY to the load path like this:
  
    (setq load-path (append load-path '("/XXX/YYY/")))
  
  To do this relative to your home directory:
  
    (setq load-path (append load-path (list (expand-file-name "~/YYY/"))))
  


Emacs Lisp programming:

80: What dialect of Lisp is Emacs Lisp?
  
  It's the dialect of Lisp called Emacs Lisp.  (No joke!)  People also
  call it elisp or e-lisp.  (NOTE: The term "Elisp" is trademarked by
  someone else.)
  
81: How close is Emacs Lisp to Common Lisp?
  
  Pretty far.  GNU Emacs Lisp is case-sensitive, uses dynamic scoping,
  doesn't have packages, doesn't have multiple return values, doesn't have
  reader macros, etc.  For people used to Common Lisp, some of the
  functions in Common Lisp that are not in Emacs Lisp by default are
  provided in the file lisp/cl.el.  There is a Texinfo manual describing
  these functions in man/cl.texinfo.
  
82: How do I execute a piece of Emacs Lisp code?
  
  There are a number of ways to execute (called "evaluate") an Emacs Lisp
  "form":
  
  * If you want it evaluated every time you run Emacs, put it in a file
    named ".emacs" in your home directory.
  
  * You can type the form in the "*scratch*" buffer, and then type C-j
    after it.  The result of evaluating the form will be inserted in the
    buffer.
  
  * In in Emacs-Lisp mode, typing M-C-x evaluates a top-level form before
    or around point.
  
  * Typing "C-x C-e" in any buffer evaluates the Lisp form immediately
    before point and prints its value in the echo area.
  
  * Typing M-ESC or M-x eval-expression allows you to type a Lisp form in
    the minibuffer which will be evaluated.
  
  * You can use M-x load-file to have Emacs evaluate all the Lisp forms in
    a file.  (To do this from Lisp use the function "load" instead.)
  
83: How do I make a set of operations fully local to a region?
  
  Use narrow-to-region inside of save-restriction.
  
84: How can I highlight a region?
  
  There are ways to get highlighting in GNU Emacs 18.57, but they all
  require patching the C code of Emacs and rebuilding.  They are also slow
  and the highlighting disappears if you scroll or redraw the screen.  One
  patch is by Kenichi Handa <handa@etl.go.jp>.
  
  You can highlight regions in a variety of ways in Epoch.  GNU Emacs 19
  will have everything you need, but won't be out soon.
  
85: How do I change Emacs's idea of the tab character's length?
  
  Example: (setq default-tab-width 10).
  
86: What is the difference between (interactive "P") and (interactive "p")?
  
  The value that is a result of "P" can be a list, a symbol, or an
  integer; the value that is a result of "p" is always an integer:
  
    Prefix keys typed       result of:   "P"        "p"
      nothing                            nil         1
      "M-1"                              1           1
      "C-u 1"                            1           1
      "M--"                              '-         -1
      "C-u -"                            '-         -1
      "C-u"                              (4)         4
      "C-u C-u"                          (16)       16
  


Carrying Out Common Tasks:

87: How do I insert ">"'s in the beginning of every line in a buffer?
  
  Type "M-x replace-regexp RET ^ RET > RET".  ("replace-regexp" can be
  shortened to "repl TAB r".)
  
  To do this only in the region, type "C-x n M-x replace-regexp RET ^ RET
  > RET C-x w".  (You're going to remember that, right?)
  
88: How do I insert "_^H" characters before each character in a
 paragraph to get an underlined paragraph?
  
  M-x underline-region.
  
89: How do I repeat a command as many times as possible?
  
  Make a keyboard macro that invokes the command and then type "M-0 C-x e".
  
  WARNING: any messages your command prints in the echo area will be
  suppressed.
  
90: How do I search for or delete unprintable (8-bit or control) characters?
  
  To search for a single character that appears in the buffer as, for
  example, \237, you can type "C-s C-q 2 3 7".  (This assumes the value of
  search-quote-char is 17 (C-q).)
  
  Searching for ALL unprintable characters is best done with a "regexp"
  search.  The easiest regexp to use for the unprintable chars is the
  complement of the regexp for the printable chars.
  
  Regexp for the printable chars: [\t\n\r\f -~]
  
  Regexp for the unprintable chars: [^\t\n\r\f -~]
  
  To type some of these special characters (\t, \n, \r, \f) as an
  interactive argument to isearch-forward-regexp or re-search-forward, you
  need to use C-q.
  
  So, to search for unprintable characters using re-search-forward:
  
    M-x re-search-forward RET [^ TAB C-q C-j C-q RET C-q C-l SPC -~] RET
  
  Using isearch-forward-regexp:
  
    M-C-s [^ TAB RET C-q RET C-q C-l SPC -~]
  
  To delete all unprintable characters, simply use a replace-regexp:
  
    M-x replace-regexp RET [^ TAB C-q C-j C-q RET C-q C-l SPC -~] RET RET
  
  Notes:
  
  * With isearch, you can type RET to get a quoted C-j.  (Not a quoted C-m.)
  
  * You don't need to quote TAB with either isearch or typing something in
    the minibuffer.
  
  Here are the Emacs Lisp forms of the above regexps:
  
    ;; regexp matching all printable characters:
    "[\t\n\r\f -~]"
  
    ;; regexp matching all unprintable characters:
    "[^\t\n\r\f -~]"
  
    ;; alternative regexps for all unprintable characters:
    "[\C-@-\C-h\C-k\C-n-\C-_\C-?-\377]"
    "[\000-\010\013\016-\037\177-\377]"
  
  (To use "[\000-\010\013\016-\037\177-\377]" interactively, type:
  
    [ C-q 000 - C-q 010 C-q 013 C-q 016 - C-q 037 C-q 177 - C-q 377 ]
  
   )
  
91: How do I control Emacs's case sensitivitiy when searching/replacing?
    
  For searching, the value of the variable case-fold-search determines
  whether they are case sensitive:
  
    (setq case-fold-search nil) ; make searches case sensitive
    (setq case-fold-search t)   ; make searches case insensitive
  
  Similarly, for replacing the variable case-replace determines whether
  replacements preserve case.
  
92: How do I tell Emacs to automatically indent a new line to the
 indentation of the previous line?
  
  M-x indented-text-mode.  (This is a major mode.)
  
  If you have Auto-Fill mode on (minor mode), you can tell Emacs to prefix
  every line with a certain character sequence, the "fill prefix".  Type
  the prefix at the beginning of a line, position point after it, and then
  type "C-x ." (set-fill-prefix) to set the fill prefix.  Thereafter,
  auto-filling will automatically put the fill prefix at the beginning of
  new lines, and M-q (fill-paragraph) will maintain any fill prefix when
  refilling the paragraph.
  
93: How do I make Emacs "typeover" or "overwrite" when I type instead of
 always inserting?
  
  M-x overwrite-mode (minor mode).  
  
94: How do I show which parenthesis matches the one I'm looking at?
  
  If you're looking at a right parenthesis (or brace or bracket) you can
  delete it and reinsert it.  Emacs will blink the cursor on the matching
  parenthesis.
  
  M-C-f (forward-sexp) and M-C-b (backward-sexp) will skip over balanced
  parentheses, so you can see which parentheses match.  (You can train it
  to skip over balanced brackets and braces at the same time by modifying
  the syntax table.)
  
  Here is some Emacs Lisp that will make the % key show the matching
  parenthese, like in vi.  In addition, if the cursor isn't over a
  parenthese, it simply inserts a % like normal.
  
  (By an unknown contributor.)
  
    (global-set-key "%" 'match-paren)
  
    (defun match-paren (arg)
      "Go to the matching parenthesis if on parenthesis otherwise insert %."
      (interactive "p")
      (cond ((looking-at "\\s\(") (forward-list 1) (backward-char 1))
	    ((looking-at "\\s\)") (forward-char 1) (backward-list 1))
	    (t (self-insert-command (or arg 1)))))
  
95: How do I make Emacs behave like this: when I go up or down, the cursor
 should stay in the same column even if the line is too short?
  
  M-x picture-mode.  (This is a minor mode, in theory anyway ...)
  
96: How do I read news under Emacs?
  
  There are at least three news reading packages that operate inside
  Emacs.  "rnews" comes with Emacs.  "GNUS" and "Gnews" come separately.
  
  {I've never used rnews; could someone write a description?  BTW, rnews
  will be replaced with GNUS in Emacs 19.}
  
  rnews does not work with NNTP.
  
  Both GNUS and Gnews handle reading news over NNTP.  I think both can
  also read from a local news spool.  GNUS also supports reading mail
  stored in MH folders or articles saved by GNUS.  People have complained
  that GNUS uses a lot of CPU time (it does).  Some people have complained
  that Gnews is slower than GNUS.
  
  GNUS is written (mostly) by Masanobu Umeda.  His latest e-mail address
  is umerin@mse.kyutech.ac.jp.  The latest version is GNUS 3.13.  There is
  a newsgroup for discussion of GNUS called gnu.emacs.gnus.  This
  newsgroup is gatewayed with the mailing list info-gnus-english to
  subscribe send mail to info-gnus-english-request@cis.ohio-state.edu.
  There is also a mailing list called info-gnus, which includes discussion
  in Japanese.
  
  Gnews was written by Matthew Wiener <e-mail address?>.  {Could someone
  tell me the # of the latest version, and how long it has been since
  anyone has heard from Matthew?}.  There is a newsgroup for Gnews called
  gnu.emacs.gnews.
  
97: In C mode, can I show just the lines that will be left after #ifdef
 commands are handled by the compiler?
  
  M-x hide-ifdef-mode.  (This is a minor mode.)
  
  You may have to (load "hideif") first.  If you want to do this
  regularly, put this in your .emacs file:
  
    (autoload 'hide-ifdef-mode "hideif" nil t)
  
  {Yes, I know, this should be in lisp/loaddefs.el already.}
  
98: Is there an equivalent to the "." (dot) command of vi?
  
  ("." is the redo command in vi.  It redoes the last insertion/deletion.)
  
  No, not really.
  
  You can type "C-x ESC" (repeat-complex-command) to reinvoke commands
  that used the minibuffer to get arguments.  In repeat-complex-command
  you can type M-p and M-n to scan through all the different complex
  commands you've typed.
  
  To repeat something on each line I recommend using keyboard macros.
  
99: How do I use emacstool under SunView?
  
  The file etc/SUN-SUPPORT includes the document "Using Emacstool with GNU
  Emacs".  Also read the man page for emacstool (etc/emacstool.1).
  
100: How do I make Emacs show the current line (column) number on the mode line?
  
  There is no "correct" way to constantly display the current line (or
  column) number on the mode line in Emacs 18.  Emacs is not a
  line-oriented editor, and really has no idea what "lines" of the buffer
  are displayed in the window.  It would require a lot of work at the C
  code level to make Emacs keep track of this.
  
  Emacs 19 will probably be able to do this, but probably not with great
  efficiency.
  
  To find out what line of the buffer you are on right now, do "M-x
  what-line".  Typing "C-x l" will also tell you what line you are on,
  provided the buffer isn't separated into "pages" with C-l characters.
  In that case, it will only tell you what line of the current "page" you
  are on.  WARNING: "C-x l" gives the wrong value when point is at the
  beginning of a line.
  
  People have written various kludges to display the current line number
  on the mode line.  Look in the Lisp Code Directory.  (See question 13.)
  
101: How do I tell Emacs to iconify itself?
  
  You need to modify C source and recompile.  Either that or get Epoch
  instead.  For the interested I have a patch to allow Emacs to iconify
  itself.
  
102: How do I use regexps (regular expressions) in Emacs?
  
  This is documented in the Emacs manual.  To read the manual section
  online, type "C-h i m emacs RET m regexps RET".
  
  WARNING: Unlike in Unix grep, sed, etc., a complement character set
  ([^...]) can match a Newline, unless Newline is mentioned as one of the
  characters not to match.