🚀 go-pugleaf

Archive-Name: GNU-Emacs-FAQ/part2
Last-Modified: Tue, 4 May 1993 02:22:35 GMT
Last-Posted: Tue, 4 May 1993 02:52:18 GMT

                 GNU Emacs FAQ: Common Requests/Problems

If you are viewing this text in a GNU Emacs Buffer, you can type "M-2 C-x $" to
get an overview of just the questions.  Then, when you want to look at the text
of the answers, just type "C-x $".

To search for a question numbered XXX, type "M-C-s ^XXX:", followed by a C-r if
that doesn't work, then type ESC to end the search.

A `+' in the 78th column means something was inserted on the line.  A `-' means
something was deleted and a `!' means some combination of insertions and
deletions occurred.

Full instructions for getting the latest FAQ are in question 22.  Also see the
`Introduction to news.answers' posting in the `news.answers' newsgroup, or send
e-mail to `mail-server@rtfm.mit.edu' with `help' on a body line, or use FTP,
WAIS, or Prospero to rtfm.mit.edu.



Common Things People Want To Do 

28:  How do I set up a .emacs file properly?
  
  See `Init File' in the on-line manual.
  
  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.  :-)
  
29:  How do I 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) LFD
    (load-file "~/.emacs") LFD
  
  (Type LFD by pressing C-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 127.
  
30:  How do I make Emacs display the current line (or column) number?
  
  To find out what line of the buffer you are on right now, do "M-x
  what-line".  Use "M-x goto-line" to go to a specific line.  To find the
  current column number, type "M-ESC (current-column)".
  
  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.
  
  There is no "correct" way to constantly display the current (or total)
  line (or column) number on the mode line in Emacs 18, or to display the
  line numbers next to the lines like vi can.  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.  It would not be that hard to get the column
  number, but it would still require changes at the C code level.
  
  None of the vi emulation modes provide the `set number' capability of vi
  (as far as I know).
  
  Emacs 19 will probably be able to show the line number on the mode-line,
  but probably very inefficiently.
  
  People have written various kludges to display line numbers.  One is
  `display-line-numbers' by Wayne Mesard <wmesard@tofu.oracle.com,
  Mesard@bbn.com>.  Look in the Lisp Code Directory.  (See question
  88.)
  
31:  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))))
  
32:  How do I turn on Auto-Fill mode by default?
  
  To turn on Auto-Fill mode just once for one buffer, use "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)
  
33:  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-*-
  
34:  How do I search for, delete, or replace 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 (ie., 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 in an interactive argument to
  isearch-forward-regexp or re-search-forward, you need to use C-q.  (`\t',
  `\n', `\r', and `\f' stand respectively for TAB, LFD, RET, and C-l.)  So,
  to search for unprintable characters using re-search-forward:
  
    M-x re-search-forward RET [^ TAB C-q LFD 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 LFD C-q RET C-q C-l SPC -~] RET RET
  
  Replacing is similar to the above.  {I need to write the text for this
  part of the answer!}
  
  Notes:
  
  * With isearch, you can type RET to get a quoted LFD (not a quoted RET).
  
  * 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 -~]"
  
35:  How can I highlight a region of text in Emacs?
  
  There are ways to get highlighting (reverse video, inverse video) in GNU
  Emacs 18.59, but either they require patching the C code of Emacs and
  rebuilding, or they are slow and the highlighting disappears if you scroll
  or redraw the screen and it can not follow the point.  Howard Gayle's
  patches for 8-bit output appear to allow highlighting (see question
  ^8-bit-output).  Another patch for highlighting is by Kenichi Handa
  <handa@etl.go.jp>.  There is a patch for use with X by Andy Norman
  <ange@hplb.hpl.hp.com> (and modified for 18.57 by Matthieu Herrb
  <matthieu@laas.fr>), which is available for FTP:
  
    /laas.laas.fr:pub/emacs/patch-X11-18.55
    /laas.laas.fr:pub/emacs/patch-X11-18.57
  
  You can highlight regions in a variety of ways in Epoch and Lucid Emacs.
  GNU Emacs 19 may not be able to just temporarily highlight a region.
  
  Similar comments apply to displaying text in different fonts, except that
  it is even harder.
  
36:  How do I control Emacs's case-sensitivity 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.
  
  To change the case sensitivity just for one major mode, use the major
  mode's hook.  For example:
  
    (setq XXX-mode-hook
          (function
	   (lambda ()
	     (setq case-fold-search nil))))
  
37:  How do I make Emacs wrap words for me?
  
  M-x auto-fill-mode.  The default maximum line width is 74, determined by
  the variable fill-column.  To find how to turn this on automatically see
  question 32.
  
38:  Where can I get a better spelling checker for Emacs?
  
  Use Ispell.  See question 119.
  
39:  How can I spell-check TeX or *roff documents?
  
  If you want to spell-check TeX or *roff documents with Ispell, you need to
  arrange for a filter program that understands how to strip TeX or *roff
  formatting commands to be run.  In the TeX distribution, there are several
  different programs named `detex', all with incompatible options, and a
  very old pair of programs named `detex' and `delatex', which should
  probably be avoided.  The most useful one for Ispell is `detex' by Daniel
  Trinkle.  A more recent version is available via FTP:
  
    /arthur.cs.purdue.edu:pub/trinkle/detex-2.4.tar
  
  Raphael Cerf <cerf@clipper.ens.fr> recently released a program for this
  named `xetal':
  
    /spi.ens.fr:pub/unix/tex/
  
  There is a program that comes with Unix named `deroff' for stripping
  formatting commands from *roff files.
  
  Here is an example of code you can put in a .emacs file to use these
  programs:
  
    ;; Based on suggestions by David G. Grubbs <dgg@ksr.com> and Paul Palmer
    ;; <palmerp@math.orst.edu>.
  
    ;; Assuming the use of detex 2.3 by Daniel Trinkle:
    ;; -w means one word per line.
    ;; -n means don't expand \input or \include commands.
    ;; -l means force LaTeX mode.
  
    (require 'ispell) ; for the make-variable-buffer-local statements
    (setq plain-TeX-mode-hook
	  (function
	   (lambda ()
	     (setq ispell-filter-hook "detex")
             (setq ispell-filter-hook-args '("-nw")))))
    (setq LaTeX-mode-hook
	  (function
	   (lambda ()
	     (setq ispell-filter-hook "detex")
             (setq ispell-filter-hook-args '("-lnw")))))
    (setq nroff-mode-hook
	  (function
	   (lambda ()
	     (setq ispell-filter-hook "deroff")
             (setq ispell-filter-hook-args '("-w")))))
  
  You will have to adjust the arguments for programs other than Trinkle's
  detex or for other versions of deroff.  Experiment running the command
  from the shell to find the correct options.  If you don't have a filter
  that knows how to output one word per line, you must pipe its output
  through another filter to break up the output.
  
40:  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/"))))
  
41:  How do I use an already running Emacs from another window?
  
  The `emacsclient' program is for editing a file using an already running
  Emacs rather than starting up a new Emacs.  It does this by sending a
  request to the already running Emacs, which must be expecting the request.
  
  * Setup
  
    Emacs must have executed the `server-start' function for emacsclient to
    work.  This can be done either by a command line option:
  
      emacs -f server-start
  
    or by invoking server-start from the .emacs file:
  
      (if (some conditions are met) (server-start))
  
    When this is done, Emacs starts a subprocess running a program called
    `server'.  `server' creates a Unix domain socket in the user's home
    directory named `.emacs_server'.
  
    To get your news reader, mail reader, etc., to invoke emacsclient, try
    setting the environment variable EDITOR (or sometimes VISUAL) to the
    value `emacsclient'.  You may have to specify the full pathname of the
    emacsclient program instead.  Examples:
  
      # csh commands:
      setenv EDITOR emacsclient
      setenv EDITOR /usr/local/emacs/etc/emacsclient  # using full pathname
  
      # sh command:
      EDITOR=emacsclient export EDITOR
  
  * Normal use
  
    When emacsclient is run, it connects to the `.emacs_server' socket and
    passes its command line options to `server'.  When `server' receives
    these requests, it sends this information on the the Emacs process,
    which at the next opportunity will visit the files specified.  (Line
    numbers can be specified just like with Emacs.)  The user will have to
    switch to the Emacs window by hand.  When the user is done editing a
    file, the user can type "C-x #" to indicate this.  This will switch to
    another buffer created at the request of emacsclient if there are any.
    When "C-x #" has been invoked on all of the files that the emacsclient
    requested to be edited, Emacs will send notification of this to `server'
    which will pass this on to the emacsclient, which will then exit.
  
  NOTE: `emacsclient' and `server' must be running on machines which share
  the same filesystem for this to work.  The pathnames that emacsclient
  specifies should be correct for the filesystem that the Emacs process
  sees.  The Emacs process should not be suspended at the time emacsclient
  is invoked.  emacsclient should either be invoked from another X window or
  from a shell window inside Emacs itself.
  
  There is an enhanced version of emacsclient/server called `gnuserv' by
  Andy Norman <ange@hplb.hpl.hp.com> which is available in the Emacs Lisp
  Archive.  gnuserv uses Internet domain sockets, so it can work across most
  network connections.  It also supports the execution of arbitrary Emacs
  Lisp forms and also does not require the client program to wait for
  completion.  It is available via anonymous FTP (Emacs Lisp Archive:
  packages/gnuserv.shar).
  
42:  How do I make Emacs recognize my compiler's funny error messages?
  
  Write a program which runs the compiler as a child and filters its output,
  rearranging as necessary.  Install with same name as compiler somewhere in
  path.
  
  Keith Moore <moore@cs.utk.edu> wrote one such for a C compiler under AIX.
  Available via FTP:
  
    /cs.utk.edu:readonly/aixcc.lex
  
  Jim Frost <jimf@saber.com> wrote another for the IBM xlc compiler on the
  RS/6000.  (I don't know if these are both for the same compiler.)
  Johnathan Vail <vail@tegra.COM> wrote something for a High C compiler
  (`hc', which is one of the compilers on the RS/6000, although I think
  Johnathan wrote his program for hc on a different computer).
  
43:  How do I indent switch statements like this?
  
  Many people want to indent their switch statements like this:
  
    f()
    {
      switch(x) {
        case A:
          x1;
          break;
        case B:
          x2;
          break;
        default:
          x3;
      }
    }
  
  I don't believe there is any way to do this exactly without modifying the
  Lisp code in c-mode.el.  You can set c-indent-level to 4 and
  c-label-offset to -2, but this has bad effects elsewhere.  {Anyone have a
  solution?}
  
44:  How can I make Emacs automatically scroll horizontally?
  
  There is no completely correct way of doing this that does not involve
  rewriting all commands or writing your own top-level command loop (not a
  completely bad idea).  Wayne Mesard <wmesard@pescadero.stanford.edu> has
  written a particularly advanced kludge called `hscroll.el' that checks
  once a second to make sure point is visible.
  
45:  How do I make Emacs "typeover" or "overwrite" instead of inserting?
  
  M-x overwrite-mode (a minor mode).
  
46:  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)
  
47:  How do I turn down the bell volume in Emacs running under X Windows?
  
  Under versions of Emacs before 18.58, the bell volume was annoying loud
  and difficult to turn off.  So upgrading to 18.58 or higher will reduce
  the volume.  If you want to turn it off completely, use `xset'.  There is
  no way to turn the bell off just for Emacs without affecting all other
  programs.
  
  Under Epoch you can do:
  
    (setq epoch::bell-volume 20)
  
  Stu Grossman <grossman@sunburn.stanford.edu> wrote a patch that allows the
  bell volume to be adjusted from inside Emacs just for Emacs.
  
48:  How do I tell Emacs to automatically indent a new line to the
 indentation of the previous line?
  
  One solution is Indented Text Mode (M-x indented-text-mode).
  
  If you have Auto-Fill mode on (a minor mode, see question 32), 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.
  
  NOTE: If you have paragraphs with different levels of indentation, you
  will have to set the fill prefix to the correct value each time you move
  to a new paragraph.  To avoid this hassle, try one of the many packages
  available from the Emacs Lisp Archive.  Look up `fill' and `indent' in the
  Lisp Code Directory for guidance.
  
49:  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
  parenthesis, like in vi.  In addition, if the cursor isn't over a
  parenthesis, 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)))))
  
50:  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.}
  
51:  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.
  
52:  What are the valid X resource settings (ie., stuff in .Xdefaults)?
  
  See the Emacs man page, or the etc/OPTIONS file.  Ignore the information
  in etc/XDOC which is way out of date.
  
53:  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 LFD (or
    C-j) after it.  The result of evaluating the form will be inserted in
    the buffer.
  
  * 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.)
  
  These functions are also used for evaluating Lisp forms:
  
    load-library, eval-region, eval-current-buffer, require, autoload
  
54:  How do I change Emacs's idea of the tab character's length?
  
  Example: (setq default-tab-width 10).
  
55:  How do I insert `>' at the beginning of every line?
  
  Type "M-x replace-regexp RET ^ RET > RET".
  
  To do this only in the region, type "C-x n M-x replace-regexp RET ^ RET
  > RET C-x w".
  
  WARNING: The command narrow-to-region (C-x n) is disabled by default
  because it can be very confusing (ie., "Oh no!  Where did my file go?").
  
56:  How do I insert `_^H' before each character in a paragraph to get an
 underlined paragraph?
  
  M-x underline-region.
  
57:  How do I repeat a command as many times as possible?
  
  Use "C-x (" and "C-x )" to 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.
  
58:  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 ...)
  
59:  How do I tell Emacs to iconify itself?
  
  You need to modify C source and recompile.  Either that or get Epoch or
  Lucid Emacs instead.  Patches have been written by Robert Forsman
  <thoth@reef.cis.ufl.edu> and Johan Vromans <jv@mh.nl> to allow Emacs to
  iconify itself and by Matt Wette <mwette@mr-ed.jpl.nasa.gov> and
  Manavendra K. Thakur <thakur@zerkalo.harvard.edu> (for 18.57, plus icon
  geometry) to allow Emacs to start up iconified.  I don't know which of
  these patches work together.
  
  Anonymous FTP:
    /csi.jpl.nasa.gov:pub/emax.patch1  (Matt Wette)
    /ftp.eu.net:gnu/emacs/FP-Xfun.Z  (Johan Vromans)
    /ftp.urc.tue.nl:/pub/tex/emacs/FP-Xfun  (Johan Vromans)
  
60:  How do I use regexps (regular expressions) in Emacs?
  
  See `Regexps' in the online manual.
  
  WARNING: The "or" operator is `\|', not `|', and the grouping operators
  are `\(' and `\)'.  Also, the string syntax for a backslash is "\\".
  Thus, the string syntax for a regular expression like xxx\(foo\|bar\) is
  "xxx\\(foo\\|bar\\)".  Notice the duplicated backslashes!
  
  WARNING: Unlike in Unix grep, sed, etc., a complement character set
  ([^...])  can match a newline character (LFD aka C-j aka \n), unless
  newline is mentioned as one of the characters not to match.
  
  WARNING: The character syntax regexps (eg. `\sw') are not meaningful
  inside character set regexps (eg. `[aeiou]').  (This is actually typical
  for regexp syntax.)
  
61:  How do I perform a replace operation across more than one file?
  
  The "tags" feature of Emacs includes the command tags-query-replace which
  performs a query-replace across all the files mentioned in the TAGS file.
  See `Tags:Tags Search' in the online manual.
  
  In addition, Martin Boyer has written a package named global-replace which
  will perform a query-replace across all the files mentioned in the
  *compilation* buffer (usually done after a `grep'), which is available via
  anonymous FTP:
  
    /ireq-robot.hydro.qc.ca:pub/emacs/lisp/compile.el.Z
    /ireq-robot.hydro.qc.ca:pub/emacs/lisp/global-replace.el.Z
    /ireq-robot.hydro.qc.ca:pub/emacs/lisp/query.el.Z
  
62:  Where is the documentation for `etags'?
  
  `etags' takes options just like a prior version of ctags, so your ctags
  manual (if any) may be useful.  Eoin Woods, in comp.emacs, writes the      !
  following:                                                                 !
                                                                             !
    From reading the source (!) the way I use it is:                         !
                                                                             !
      for f in `find <args>`                                                 !
      do                                                                     !
         etags -at -f ETAGS $f                                               !
      done                                                                   !
                                                                             !
    The "-t" option means to create tags for typedefs as well as functions.  !
    The "-a" option tells it to append to the output file. If you have a     !
    small number of files (up to a few hundred I think) you can use it       !
    direct as:                                                               !
                                                                             !
      etags -f ETAGS file1 file2 file3 ... filen                             !
                                                                             !
    The option list is:                                                      !
                                                                             !
            -f file -  Specify the output file name (Default is "TAGS")      !
            -a      -  Append to the output file. (Default is to rewrite it) !
            -t      -  Create tags for typedefs (default is just functions)  !
            -u      -  Update the output file. Do not re-create it.          !
            -w      -  Suppress warnings                                     !
            -v      -  Create vgrind style indexed output (What is vgrind??) !
            -x      -  Create cxref style output (default is Emacs Tags)     !
            -e      -  Emacs tags style output (the default the way I        !
                       compile it)                                           !
                                                                             !
    Having got it working, it works fine!                                    !
  


Bugs/Problems

63:  Does Emacs have problems with files larger than 8 megabytes?
  
  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 8,388,607 bytes (2^23 - 1).
  
  Leonard N. Zubkoff <lnz@lucid.com> suggests putting the following two
  lines in src/config.h before compiling Emacs to allow for 26-bit integers
  and pointers (and thus filesizes of up to 33,554,431 bytes):
  
    #define VALBITS 26
    #define GCTYPEBITS 5
  
  WARNING: This method may result in `ILLEGAL DATATYPE' and other random
  errors on some machines.
  
  David Gillespie <daveg@csvax.cs.caltech.edu> gives an explanation of why
  Emacs uses 24 bit integers and pointers:
  
    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, eg.,
    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.
  
64:  Why can't Emacs find files in current directory on startup?
  
  The PWD bug has been fixed as of GNU Emacs 18.59.  Read on if you are
  running an older version of Emacs.

  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.  An invalid
  setting for PWD can also be a problem if you use X Windows and csh on an
  RS/6000.  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.
  
  You may have PWD set for other reasons.  Another possibility is that you
  are setting default-directory from your .emacs file.
  
  Here is a fix by Jim Blandy <jimb@occs.cs.oberlin.edu>:
  
    >--- emacs/jjj/emacs-18.58/lisp/startup.el	Tue Jan 15 23:19:04 1991
    >+++ startup.el	Mon Apr 20 00:21:01 1992
    >@@ -81,5 +81,7 @@
    >     ;; In presence of symlinks, switch to cleaner form of default directory.
    >     (if (and (not (eq system-type 'vax-vms))
    >-	     (getenv "PWD"))
    >+	     (getenv "PWD")
    >+ 	     (equal (nthcdr 10 (file-attributes default-directory))
    >+ 		    (nthcdr 10 (file-attributes (getenv "PWD")))))
    > 	(setq default-directory (file-name-as-directory (getenv "PWD"))))
    >     (unwind-protect
  
65:  How do I get rid of the ^M junk in my Shell buffer?
  
  For tcsh, put this in your `.cshrc' (or `.tcshrc') file:
  
    if ($?EMACS) then
        if ("$EMACS" == t) then
	    if ($?tcsh) unset edit
	    stty nl
	endif
    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
  
  (You must start Emacs over again with the environment variable properly
  set for this to take effect.)
  
66:  Why do I get `Process shell exited abnormally with code 1'?
  
  The most likely reason for this message is that the `env' program is not
  properly installed.  This program should be compiled (for the correct
  architecture!) and installed with execute permission for everyone in
  Emacs's program directory, which is normally /usr/local/emacs/etc.  You
  can find what this directory is at your site by inspecting the value of
  the variable exec-directory by typing "C-h v exec-directory RET".  `env'
  should also be for the correct architecture (check using `file' command).
  
  You should also check for other programs named `env' in your path (eg.,
  SunOS has a program named /usr/bin/env).  I don't understand why this can
  cause a failure and I don't know a general solution for working around the
  problem in this case.
  
  The `make clean' command will remove `env' and other vital programs, so be
  careful when using it.
  
  It has been reported that this sometimes happened when Emacs was started
  as an X client from an xterm window (ie. had a controlling tty) but the
  xterm was later terminated.
  
  See also etc/PROBLEMS for other possible causes of this message.
  
67:  Why can't I cut from Emacs and paste in other X programs?
  
  Emacs stores things you "cut" in the X "cut buffers".  It also pastes from
  the cut buffer `CUT_BUFFER0'.  This is obsolete.  Most modern X programs
  now expect to work with "selections" instead of cut buffers, although some
  like `xterm' will try to use the cut buffers if the selection is null.
  
  Emacs 18.58 contains a "fix" that makes xterm work by default.  This
  "fix" is that Emacs clears the `PRIMARY' selection when it stores
  something in the cut buffer.  By making the selection null, xterm will
  then fetch from the cut buffer when you try to paste.
  
  For versions of Emacs prior to 18.58, you can make pasting from Emacs into
  xterm work with the following X resources:
  
    ! Solution by Thomas Narten, should work under X11R3 and later GNU
    ! Emacs only copies to CUT_BUFFER0.  xterm by default wants to paste
    ! from the PRIMARY selection.
    XTerm*VT100.Translations: #override \
        ~Meta <Btn2Up>: insert-selection(CUT_BUFFER0,PRIMARY)
  
  You may have problems copying between Emacs and programs other than xterm
  that won't store cut text in the cut buffers or look in the cut buffers
  for text to paste (for backwards compatibility with obsolete applications
  like Emacs :-).  The best workaround is to use the `xcutsel' program as an
  intermediary.
  
  This problem does not exist for Epoch or Lucid Emacs.
  
68:  Where is the termcap/terminfo entry for terminal type `emacs'?
  
  The termcap entry for terminal type `emacs' is ordinarily put in the
  TERMCAP environment variable of subshells.  It may help in certain
  situations (eg., using rlogin from shell buffer) to add an entry for
  `emacs' to the system-wide termcap file.  Here is a correct termcap entry
  for `emacs':
  
    emacs:tc=unknown:
  
  To make a terminfo entry for `emacs', use `tic' or `captoinfo'.  You need
  to generate /usr/lib/terminfo/e/emacs.  It may work to simply copy
  /usr/lib/terminfo/d/dumb to /usr/lib/terminfo/e/emacs.
  
  Having a termcap/terminfo entry will not enable the use of full screen
  programs in shell buffers.  Use M-x terminal-emulator for that instead.
  
  A workaround to the problem of missing termcap/terminfo entries is to
  change terminal type `emacs' to type `dumb' or `unknown' in your shell
  start up file.  `csh' users could put this in their .cshrc files:
  
    if ("$term" == emacs) set term=dumb
  
69:  Why does Emacs spontaneously start displaying `I-search:' and beeping?
  
  Your terminal (or something between your terminal and the computer) is
  sending C-s and C-q for flow control, and Emacs is receiving these
  characters and interpreting them as commands.  (The C-s character normally
  invokes the isearch-forward command.)  For possible solutions, see
  question 131.
  
70:  Why can't Emacs talk to certain hosts (or certain hostnames)?
  
  The problem may be that Emacs is linked with a wimpier version of
  gethostbyname than the rest of the programs on the machine.  This is often
  manifested as a message on startup of `X server not responding.  Check
  your DISPLAY environment variable.' or a message of `Unknown host' from
  open-network-stream.
  
  On a Sun, this may be because Emacs had to be linked with the static C
  library.  The version of gethostbyname in the static C library may only
  look in /etc/hosts and the NIS (YP) maps, while the version in the dynamic
  C library may be smart enough to check DNS in addition to or instead of
  NIS.  On a Motorola Delta running System V R3.6, the version of
  gethosbyname in the standard library works, but the one that works with
  NIS doesn't (the one you get with -linet).  Other operating systems have
  similar problems.
  
  Try these options:
  
  * Explicitly add the host you want to communicate with to /etc/hosts.
  
  * Relink Emacs with this line in src/config.h:
  
      #define LIBS_SYSTEM -lresolv
  
  * Replace gethostbyname and friends in libc.a with more useful versions
    such as the ones in libresolv.a.  Then relink Emacs.
  
  * If you are actually running NIS, make sure that `ypbind' is properly
    told to do DNS lookups with the correct command line switch.
  
  * Use tcp.el and tcp.c from GNUS.  This has the additional advantage that
    you can use numeric IP addresses instead of names.  open-network-stream
    currently can't handle numeric addresses.  Brian Thomson
    <thomson@hub.toronto.edu> has a enhancement to open-network-stream to
    allow it to handle numeric addresses.
  
71:  Why does Emacs say `Error in init file'?
  
  An error occurred while loading either your .emacs file or the system-wide
  lisp/default.el file.  For information on how to debug your .emacs file,
  see question 29.
  
  It may be the case that you may need to load some package first, or use a
  hook that will be evaluated after the package is loaded.  A common case of
  this is explained in question 127.
  
72:  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.
  
  * Make sure you are either using the class name of `Emacs' (oops,
    apparently this is buggy in Emacs 18.58!) or the correct instance name.
    The instance name is normally the same as the name of the file Emacs is
    in (ie., the last part of argv[0]), but this can be overridden by -rn
    command line option or the WM_RES_NAME environment variable.
  
    WARNING: Reports say using the class name fails in Emacs 18.58.
  
    WARNING: The advice the man page gives to use `emacs' is often wrong.
  
    WARNING: Older versions of Emacs got the class name wrong.
  
  * Emacs currently ignores the -xrm command line argument.
  
  * Emacs does not yet handle X11R5 screen-specific resources.
  
  * Emacs has a bug where it ignores color specifications if running on a
    1-bit display (ie. a non-color display).
  
  * I don't think Emacs will use either of the application-specific resource
    files.  Thus these environment variables don't affect it: XAPPLRESDIR,
    XUSERFILESEARCHPATH, XFILESEARCHPATH.  {Correct?}
  
73:  Why does Emacs take 20 seconds to visit a file?
  
  The usual cause is that the master lock file, `!!!SuperLock!!!' has been
  left in the lock directory somehow.  Delete it.
  
  Mark Meuer <meuer@geom.umn.edu> says that NeXT NFS has a bug where an
  exclusive create succeeds but returns an error status.  This can cause the
  same problem.  Since Emacs's file locking doesn't work over NFS anyway,
  the best solution is to recompile Emacs with CLASH_DETECTION undefined.
  
74:  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.
  
75:  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 huge variety of fixes and enhancements to Shell mode for
  this problem have been written to handle this problem.  Check the Lisp
  Code Directory (see question 88).
  
76:  Why doesn't my change to load-path work?
  
  If you added a directory name containing a tilde (~) to your load-path,
  expecting the tilde to be interpreted as your home directory, then you
  need to do something like this:
  
    (setq load-path (mapcar 'expand-file-name load-path))
  
77:  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 or disable
  this command by doing one of these two:
  
    (define-key ctl-x-map "\C-n" nil)
    (put 'set-goal-column 'disabled t)
  
78:  Why does Emacs hang with message `Unknown XMenu error' with X11R4?
  
  Many different X errors can produce this message.  Here is the solution
  to one problem:
  
  X11 Release 4 (and later, including OpenWindows) 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'.
  
79:  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 18.58.  (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 already using 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.  Assuming the existence of a group
  named `kmem', here is an example of how to do this:
  
    chgrp kmem /dev/kmem
    chmod g+r /dev/kmem
    chgrp kmem /usr/local/emacs/etc/loadst
    chmod g+s /usr/local/emacs/etc/loadst
  
  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.
  
80:  Why does ispell sometimes ignore the local dictionary?
  
  You need to update the version of Ispell to 2.0.02.  (Or you can switch to
  version 3.0 which is still in beta-testing.)  A patch is available via
  anonymous FTP:

    /archive.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".
  
81:  Why does Ispell treat each line as a single word?
  
  Ispell expects to get its input one word per line.  The ispell filter,
  which is specified by the variables ispell-filter-hook and
  ispell-filter-hook-args, should output at most one word per line.
  
82:  Are there any security risks in GNU Emacs?
  
  * the `movemail' incident (No, this is not a risk.)
  
    Cliff Stoll in his book `The Cuckoo's Egg' describes this in chapter 4.
    The site at LBL had installed the `etc/movemail' program setuid root.
    Since `movemail' had not been designed for this situation, a security
    hole was created and users could get root priveleges.
  
    `movemail' has since been changed so that even if it is installed setuid
    root this security hole will not be a result.
  
    I have heard unverified reports that the Internet worm took advantage of
    this configuration problem.
  
  * the file-local-variable feature (Yes, a risk, but easy to change.)
  
    There is an Emacs feature that allows the setting of local values for
    variables when editing a file by including specially formatted text near
    the end of the file.  This feature also includes the ability to have
    arbitrary Emacs Lisp code evaluated when the file is visited.
    Obviously, there is a potential for Trojan horses to exploit this
    feature.
  
    If you set the variable inhibit-local-variables to a non-nil value,
    Emacs will display the special local variable settings of a file that
    you visit and ask you if you really want them.  This variable is not
    mentioned in the manual.
  
    It is wise to do this in lisp/site-init.el before building Emacs:
  
      (setq inhibit-local-variables t)
  
    If Emacs has already been built, the expression can be put in
    lisp/default.el instead, or an individual can put it in their own .emacs
    file.
  
    The ability to exploit this feature by sending e-mail to an RMAIL user
    was fixed sometime after Emacs 18.52.  However, any new package that
    uses find-file or find-file-noselect has to be careful about this.
  
    For more information, see `File Variables' in the online manual (which,
    incidentally, does not describe how to disable the feature).
  
    There is a new variable in Emacs 18.58 named ignore-local-eval which
    turns out to be useless as currently implemented.  Ignore it.
  
  * synthetic X events (Yes, a risk, use MIT-MAGIC-COOKIE-1 or better.)
  
    Emacs accepts synthetic X events generated by the SendEvent request as
    though they were regular events.  As a result, if you are using the
    trivial host-based authentication, other users who can open X
    connections to your X workstatation can make your Emacs process do
    anything, including run other processes with your priveleges.
  
    The only fix for this is to prevent other users from being able to open
    X connections.  The standard way to prevent this is to use a real
    authentication mechanism, such as MIT-MAGIC-COOKIE-1.  If using the
    `xauth' program has any effect, then you are probably using
    MIT-MAGIC-COOKIE-1.  Your site may be using a superior authentication
    method; ask your system administrator.
  
    If real authentication is not a possibility, you may be satisfied by
    just allowing hosts access for brief intervals while you start your X
    programs, then removing the access.  This reduces the risk somewhat by
    narrowing the time window when hostile users would have access, but DOES
    NOT ELIMINATE THE RISK.
  
    Lucid GNU Emacs does not accept synthetic X events unless you set a
    variable.
  
  * autosave file permissions (Yes, a risk, hard to work around.)
  
    The file permissions for autosave files are determined solely by the
    Emacs process's `umask' value.  The permissions of the file being
    autosaved are not used.  The easiest workaround is to keep sensitive
    files in protected directories.  Sebastian Kremer has written an
    enhanced version of the autosave file name picking code that can avoid
    this problem by keeping autosave files in a protected directory.  {FTP
    information please?}  This problem will be fixed in Emacs 19.
  


Difficulties Building/Installing/Porting Emacs

83:  What should I do if I have trouble building Emacs?
  
  First look in the file etc/PROBLEMS to see if there is already a solution
  for your problem.  Next check the FAQ (you're reading it).  If you don't
  find a solution, then report your problem via e-mail to
  bug-gnu-emacs@prep.ai.mit.edu.  Please do not post it to gnu.emacs.help or
  e-mail it to help-gnu-emacs@prep.ai.mit.edu.  For further guidelines, see
  question 8.
  
84:  How do I stop Emacs from failing when the executable is stripped?
  
  Don't do that.
  
  This problem has been reported on SGI Indigo machines running Irix 4.0.*
  and RS/6000 machines.  Scott Henry <scotth@hoshi.corp.SGi.COM> posted a
  patch that fixes the problem for Irix.
  
85:  Why does linking Emacs with -lX11 fail?
  
  Emacs needs to be linked with the static version of the X11 library,
  libX11.a.  This may be missing.
  
  Under OpenWindows, you may need to use `add_services' to add the
  `OpenWindows Programmers' optional software category from the CD-ROM.
  
  Under HP-UX 8.0, you may need to run `update' again to load the
  X11-PRG `fileset'.  This may be missing even if you specified `all
  filesets' the first time.  If libcurses.a is missing, you may need to load
  the `Berkeley Development Option' {???}.
  
  If you are building the MIT X11 sources, you may need to modify your
  `site.cf' file to get static versions of the libraries.  (Info from David
  Zuhn <zoo@cygnus.com>.)
  
  Other systems may have similar problems.  You can always define
  CANNOT_DUMP and link with the shared libraries instead.
  
  To get the Xmenu stuff to work, you need to find a copy of MIT's
  liboldX.a.
  
86:  Why does Emacs 18.55 say `Fatal error (6).Abort' under SunOS 4.1?
  
  I had hoped this question would go away after Emacs 18.57 was released,
  but people continue to compile 18.55.  Easiest solution: upgrade.
  
  This is a result of the SunOS localtime/tzsetwall malloc bug, which was
  (finally!) fixed in SunOS 4.1.2.  If you actually need the full
  explanation, send me e-mail.  If you absolutely must compile Emacs 18.55
  (eg., you are compiling Nemacs), the easiest workaround was to put
  `#define SYSTEM_MALLOC' in src/config.h.
  


----------------------------------------------------------------------
Copyright (C) 1990, 1991, 1992 Joseph Brian Wells
Copyright (C) 1992, 1993 Steven Byrnes

This list of frequently asked questions about GNU Emacs with answers
("FAQ") may be translated into other languages, transformed into other
formats (e.g. Texinfo, Info, WWW, WAIS, etc.), and updated with new
information.  The same conditions apply to any derivative of the FAQ as
apply to the FAQ itself.  Every copy of the FAQ must include this notice
or an approved translation, information on who is currently maintaining
the FAQ and how to contact them (including their e-mail address), and
information on where the latest version of the FAQ is archived (including
FTP information).  The FAQ may be copied and redistributed under these
conditions, except that the FAQ may not be embedded in a larger literary
work unless that work itself allows free copying and redistribution.