1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2011
3 @c Free Software Foundation, Inc.
4 @c See file emacs.texi for copying conditions.
6 @chapter Miscellaneous Commands
8 This chapter contains several brief topics that do not fit anywhere
9 else: viewing ``document files'', reading netnews, running shell
10 commands and shell subprocesses, using a single shared Emacs for
11 utilities that expect to run an editor as a subprocess, printing
12 hardcopy, sorting text, narrowing display to part of the buffer,
13 editing double-column files and binary files, saving an Emacs session
14 for later resumption, following hyperlinks, browsing images, emulating
15 other editors, and various diversions and amusements.
23 @node Document View, Gnus, Calendar/Diary, Top
24 @section Document Viewing
28 @cindex Postscript file
29 @cindex OpenDocument file
30 @cindex Microsoft Office file
33 @cindex document viewer (DocView)
36 DocView mode (@code{doc-view-mode}) is a viewer for DVI, Postscript
37 (PS), PDF, OpenDocument, and Microsoft Office documents. It provides
38 features such as slicing, zooming, and searching inside documents. It
39 works by converting the document to a set of images using the
40 @command{gs} (GhostScript) command and other external tools
41 @footnote{@code{gs} is a hard requirement. For DVI files,
42 @code{dvipdf} or @code{dvipdfm} is needed. For OpenDocument and
43 Microsoft Office documents, the @code{unoconv} tool is needed.}, and
44 displaying those images.
46 @findex doc-view-toggle-display
47 @findex doc-view-toggle-display
48 @cindex doc-view-minor-mode
49 When you visit a document file with the exception of Postscript
50 files, Emacs automatically switches to DocView mode if possible
51 @footnote{The needed external tools for this document type have to be
52 available, emacs needs to run in a graphical frame, and PNG image
53 support has to be compiled into emacs. If any of these requirements
54 is not fulfilled, DocView falls back to an appropriate mode.}. When
55 you visit a Postscript file, Emacs switches to PS mode, a major mode
56 for editing Postscript files as text; however, it also enables DocView
57 minor mode, so you can type @kbd{C-c C-c} to view the document with
58 DocView. (PDF and DVI files, unlike Postscript files, are not usually
59 human-editable.) In either case, repeating @kbd{C-c C-c}
60 (@code{doc-view-toggle-display}) toggles between DocView and the file
63 You can explicitly toggle DocView mode with the command @code{M-x
64 doc-view-mode}, and DocView minor mode with the command @code{M-x
67 When DocView mode starts, it displays a welcome screen and begins
68 formatting the file, page by page. It displays the first page once
69 that has been formatted.
71 @findex doc-view-enlarge
72 @findex doc-view-shrink
73 @vindex doc-view-resolution
74 When in DocView mode, you can enlarge or shrink the document with
75 @kbd{+} (@code{doc-view-enlarge}) and @kbd{-}
76 (@code{doc-view-shrink}). To specify the default size for DocView,
77 set or customize the variable @code{doc-view-resolution}.
79 To kill the DocView buffer, type @kbd{k}
80 (@code{doc-view-kill-proc-and-buffer}). To bury it, type @kbd{q}
84 * Navigation:: Navigation inside DocView buffers.
85 * Searching:: Searching inside documents.
86 * Slicing:: Specifying which part of pages should be displayed.
87 * Conversion:: Influencing and triggering conversion.
91 @subsection Navigation
93 When in DocView mode, you can scroll the current page using the usual
94 Emacs movement keys: @kbd{C-p}, @kbd{C-n}, @kbd{C-b}, @kbd{C-f}, and
97 @vindex doc-view-continuous
98 By default, the line-motion keys @kbd{C-p} and @kbd{C-n} stop
99 scrolling at the beginning and end of the current page, respectively.
100 However, if you change the variable @code{doc-view-continuous} to a
101 non-@code{nil} value, then @kbd{C-p} displays the previous page if you
102 are already at the beginning of the current page, and @kbd{C-n}
103 displays the next page if you are at the end of the current page.
105 @findex doc-view-next-page
106 @findex doc-view-previous-page
107 You can also display the next page by typing @kbd{n}, @key{next} or
108 @kbd{C-x ]} (@code{doc-view-next-page}). To display the previous
109 page, type @kbd{p}, @key{prior} or @kbd{C-x [}
110 (@code{doc-view-previous-page}).
112 @findex doc-view-scroll-up-or-next-page
113 @findex doc-view-scroll-down-or-previous-page
114 The @key{SPC} (@code{doc-view-scroll-up-or-next-page}) key is a
115 convenient way to advance through the document. It scrolls within the
116 current page or advances to the next. @key{DEL} moves backwards in a
117 similar way (@code{doc-view-scroll-down-or-previous-page}).
119 @findex doc-view-first-page
120 @findex doc-view-last-page
121 @findex doc-view-goto-page
122 To go to the first page, type @kbd{M-<}
123 (@code{doc-view-first-page}); to go to the last one, type @kbd{M->}
124 (@code{doc-view-last-page}). To jump to a page by its number, type
125 @kbd{M-g M-g} or @kbd{M-g g} (@code{doc-view-goto-page}).
128 @subsection Searching
130 While in DocView mode, you can search the file's text for a regular
131 expression (@pxref{Regexps}). The interface for searching is inspired
132 by @code{isearch} (@pxref{Incremental Search}).
134 @findex doc-view-search
135 @findex doc-view-search-backward
136 @findex doc-view-show-tooltip
137 To begin a search, type @kbd{C-s} (@code{doc-view-search}) or
138 @kbd{C-r} (@code{doc-view-search-backward}). This reads a regular
139 expression using a minibuffer, then echoes the number of matches found
140 within the document. You can move forward and back among the matches
141 by typing @kbd{C-s} and @kbd{C-r}. DocView mode has no way to show
142 the match inside the page image; instead, it displays a tooltip (at
143 the mouse position) listing all matching lines in the current page.
144 To force display of this tooltip, type @kbd{C-t}
145 (@code{doc-view-show-tooltip}).
147 To start a new search, use the search command with a prefix
148 argument; i.e., @kbd{C-u C-s} for a forward search or @kbd{C-u C-r}
149 for a backward search.
154 Documents often have wide margins for printing. They are annoying
155 when reading the document on the screen, because they use up screen
156 space and can cause inconvenient scrolling.
158 @findex doc-view-set-slice
159 @findex doc-view-set-slice-using-mouse
160 With DocView you can hide these margins by selecting a @dfn{slice}
161 of pages to display. A slice is a rectangle within the page area;
162 once you specify a slice in DocView, it applies to whichever page you
165 To specify the slice numerically, type @kbd{s s}
166 (@code{doc-view-set-slice}); then enter the top left pixel position
167 and the slice's width and height.
168 @c ??? how does this work?
170 A more convenient graphical way to specify the slice is with @kbd{s
171 m} (@code{doc-view-set-slice-using-mouse}), where you use the mouse to
173 @c ??? How does this work?
175 @findex doc-view-reset-slice
176 To cancel the selected slice, type @kbd{s r}
177 (@code{doc-view-reset-slice}). Then DocView shows the entire page
178 including its entire margins.
181 @subsection Conversion
183 @vindex doc-view-cache-directory
184 @findex doc-view-clear-cache
185 For efficiency, DocView caches the images produced by @command{gs}.
186 The name of this directory is given by the variable
187 @code{doc-view-cache-directory}. You can clear the cache directory by
188 typing @code{M-x doc-view-clear-cache}.
190 @findex doc-view-kill-proc
191 @findex doc-view-kill-proc-and-buffer
192 To force a reconversion of the currently viewed document, type
193 @kbd{r} or @kbd{g} (@code{revert-buffer}). To kill the converter
194 process associated with the current buffer, type @kbd{K}
195 (@code{doc-view-kill-proc}). The command @kbd{k}
196 (@code{doc-view-kill-proc-and-buffer}) kills the converter process and
199 The zoom commands @kbd{+} (@code{doc-view-enlarge}) and @kbd{-}
200 (@code{doc-view-shrink}) need to reconvert the document at the new
201 size. The current page is converted first.
203 @node Gnus, Shell, Document View, Top
206 @cindex reading netnews
208 Gnus is an Emacs package primarily designed for reading and posting
209 Usenet news. It can also be used to read and respond to messages from a
210 number of other sources---mail, remote directories, digests, and so on.
211 Here we introduce Gnus and describe several basic features.
213 For full details, see @ref{Top, Gnus,, gnus, The Gnus Manual}.
216 For full details on Gnus, type @kbd{C-h i} and then select the Gnus
221 To start Gnus, type @kbd{M-x gnus @key{RET}}.
224 * Buffers of Gnus:: The group, summary, and article buffers.
225 * Gnus Startup:: What you should know about starting Gnus.
226 * Summary of Gnus:: A short description of the basic Gnus commands.
229 @node Buffers of Gnus
230 @subsection Gnus Buffers
232 Unlike most Emacs packages, Gnus uses several buffers to display
233 information and to receive commands. The three Gnus buffers users use
234 most are the @dfn{group buffer}, the @dfn{summary buffer} and the
235 @dfn{article buffer}.
237 The @dfn{group buffer} contains a list of newsgroups. This is the
238 first buffer Gnus displays when it starts up. It normally displays
239 only the groups to which you subscribe and that contain unread
240 articles. Use this buffer to select a specific group.
242 The @dfn{summary buffer} lists one line for each article in a single
243 group. By default, the author, the subject and the line number are
244 displayed for each article, but this is customizable, like most aspects
245 of Gnus display. The summary buffer is created when you select a group
246 in the group buffer, and is killed when you exit the group. Use this
247 buffer to select an article.
249 The @dfn{article buffer} displays the article. In normal Gnus usage,
250 you see this buffer but you don't select it---all useful
251 article-oriented commands work in the summary buffer. But you can
252 select the article buffer, and execute all Gnus commands from that
253 buffer, if you want to.
256 @subsection When Gnus Starts Up
258 At startup, Gnus reads your @file{.newsrc} news initialization file
259 and attempts to communicate with the local news server, which is a
260 repository of news articles. The news server need not be the same
261 computer you are logged in on.
263 If you start Gnus and connect to the server, but do not see any
264 newsgroups listed in the group buffer, type @kbd{L} or @kbd{A k} to get
265 a listing of all the groups. Then type @kbd{u} to toggle
266 subscription to groups.
268 The first time you start Gnus, Gnus subscribes you to a few selected
269 groups. All other groups start out as @dfn{killed groups} for you; you
270 can list them with @kbd{A k}. All new groups that subsequently come to
271 exist at the news server become @dfn{zombie groups} for you; type @kbd{A
272 z} to list them. You can subscribe to a group shown in these lists
273 using the @kbd{u} command.
275 When you quit Gnus with @kbd{q}, it automatically records in your
276 @file{.newsrc} and @file{.newsrc.eld} initialization files the
277 subscribed or unsubscribed status of all groups. You should normally
278 not edit these files manually, but you may if you know how.
280 @node Summary of Gnus
281 @subsection Summary of Gnus Commands
283 Reading news is a two-step process:
287 Choose a group in the group buffer.
290 Select articles from the summary buffer. Each article selected is
291 displayed in the article buffer in a large window, below the summary
292 buffer in its small window.
295 Each Gnus buffer has its own special commands; the meanings of any
296 given key in the various Gnus buffers are usually analogous, even if
297 not identical. Here are commands for the group and summary buffers:
300 @kindex q @r{(Gnus Group mode)}
301 @findex gnus-group-exit
303 In the group buffer, update your @file{.newsrc} initialization file
306 In the summary buffer, exit the current group and return to the
307 group buffer. Thus, typing @kbd{q} twice quits Gnus.
309 @kindex L @r{(Gnus Group mode)}
310 @findex gnus-group-list-all-groups
312 In the group buffer, list all the groups available on your news
313 server (except those you have killed). This may be a long list!
315 @kindex l @r{(Gnus Group mode)}
316 @findex gnus-group-list-groups
318 In the group buffer, list only the groups to which you subscribe and
319 which contain unread articles.
321 @kindex u @r{(Gnus Group mode)}
322 @findex gnus-group-unsubscribe-current-group
323 @cindex subscribe groups
324 @cindex unsubscribe groups
326 In the group buffer, unsubscribe from (or subscribe to) the group listed
327 in the line that point is on. When you quit Gnus by typing @kbd{q},
328 Gnus lists in your @file{.newsrc} file which groups you have subscribed
329 to. The next time you start Gnus, you won't see this group,
330 because Gnus normally displays only subscribed-to groups.
332 @kindex C-k @r{(Gnus)}
333 @findex gnus-group-kill-group
335 In the group buffer, ``kill'' the current line's group---don't
336 even list it in @file{.newsrc} from now on. This affects future
337 Gnus sessions as well as the present session.
339 When you quit Gnus by typing @kbd{q}, Gnus writes information
340 in the file @file{.newsrc} describing all newsgroups except those you
343 @kindex SPC @r{(Gnus)}
344 @findex gnus-group-read-group
346 In the group buffer, select the group on the line under the cursor
347 and display the first unread article in that group.
350 In the summary buffer,
354 Select the article on the line under the cursor if none is selected.
357 Scroll the text of the selected article (if there is one).
360 Select the next unread article if at the end of the current article.
363 Thus, you can move through all the articles by repeatedly typing @key{SPC}.
365 @kindex DEL @r{(Gnus)}
367 In the group buffer, move point to the previous group containing
370 @findex gnus-summary-prev-page
371 In the summary buffer, scroll the text of the article backwards.
374 @findex gnus-group-next-unread-group
375 @findex gnus-summary-next-unread-article
377 Move point to the next unread group, or select the next unread article.
380 @findex gnus-group-prev-unread-group
381 @findex gnus-summary-prev-unread-article
383 Move point to the previous unread group, or select the previous
386 @kindex C-n @r{(Gnus Group mode)}
387 @findex gnus-group-next-group
388 @kindex C-p @r{(Gnus Group mode)}
389 @findex gnus-group-prev-group
390 @kindex C-n @r{(Gnus Summary mode)}
391 @findex gnus-summary-next-subject
392 @kindex C-p @r{(Gnus Summary mode)}
393 @findex gnus-summary-prev-subject
396 Move point to the next or previous item, even if it is marked as read.
397 This does not select the article or group on that line.
399 @kindex s @r{(Gnus Summary mode)}
400 @findex gnus-summary-isearch-article
402 In the summary buffer, do an incremental search of the current text in
403 the article buffer, just as if you switched to the article buffer and
406 @kindex M-s @r{(Gnus Summary mode)}
407 @findex gnus-summary-search-article-forward
408 @item M-s @var{regexp} @key{RET}
409 In the summary buffer, search forward for articles containing a match
416 @subsection Where to Look Further
418 @c Too many references to the name of the manual if done with xref in TeX!
419 Gnus is powerful and customizable. Here are references to a few
425 additional topics in @cite{The Gnus Manual}:
429 Follow discussions on specific topics.@*
430 See section ``Threading.''
433 Read digests. See section ``Document Groups.''
436 Refer to and jump to the parent of the current article.@*
437 See section ``Finding the Parent.''
440 Refer to articles by using Message-IDs included in the messages.@*
441 See section ``Article Keymap.''
444 Save articles. See section ``Saving Articles.''
447 Have Gnus score articles according to various criteria, like author
448 name, subject, or string in the body of the articles.@*
449 See section ``Scoring.''
452 Send an article to a newsgroup.@*
453 See section ``Composing Messages.''
459 Follow discussions on specific topics.@*
460 @xref{Threading, , Reading Based on Conversation Threads,
461 gnus, The Gnus Manual}.
464 Read digests. @xref{Document Groups, , , gnus, The Gnus Manual}.
467 Refer to and jump to the parent of the current article.@*
468 @xref{Finding the Parent, , , gnus, The Gnus Manual}.
471 Refer to articles by using Message-IDs included in the messages.@*
472 @xref{Article Keymap, , , gnus, The Gnus Manual}.
475 Save articles. @xref{Saving Articles, , , gnus, The Gnus Manual}.
478 Have Gnus score articles according to various criteria, like author
479 name, subject, or string in the body of the articles.@*
480 @xref{Scoring, , , gnus, The Gnus Manual}.
483 Send an article to a newsgroup.@*
484 @xref{Composing Messages, , , gnus, The Gnus Manual}.
489 @node Shell, Emacs Server, Gnus, Top
490 @section Running Shell Commands from Emacs
492 @cindex shell commands
494 Emacs has commands for passing single command lines to inferior shell
495 processes; it can also run a shell interactively with input and output
496 to an Emacs buffer named @samp{*shell*} or run a shell inside a terminal
500 @item M-! @var{cmd} @key{RET}
501 Run the shell command line @var{cmd} and display the output
502 (@code{shell-command}).
503 @item M-| @var{cmd} @key{RET}
504 Run the shell command line @var{cmd} with region contents as input;
505 optionally replace the region with the output
506 (@code{shell-command-on-region}).
507 @item M-& @var{cmd} @key{RET}
508 Run the shell command line @var{cmd} asynchronously, and display the
509 output (@code{async-shell-command}).
511 Run a subshell with input and output through an Emacs buffer.
512 You can then give commands interactively.
514 Run a subshell with input and output through an Emacs buffer.
515 You can then give commands interactively.
516 Full terminal emulation is available.
519 @kbd{M-x eshell} invokes a shell implemented entirely in Emacs. It
520 is documented in a separate manual. @xref{Top,Eshell,Eshell, eshell,
521 Eshell: The Emacs Shell}.
524 * Single Shell:: How to run one shell command and return.
525 * Interactive Shell:: Permanent shell taking input via Emacs.
526 * Shell Mode:: Special Emacs commands used with permanent shell.
527 * Shell Prompts:: Two ways to recognize shell prompts.
528 * History: Shell History. Repeating previous commands in a shell buffer.
529 * Directory Tracking:: Keeping track when the subshell changes directory.
530 * Options: Shell Options. Options for customizing Shell mode.
531 * Terminal emulator:: An Emacs window as a terminal emulator.
532 * Term Mode:: Special Emacs commands used in Term mode.
533 * Paging in Term:: Paging in the terminal emulator.
534 * Remote Host:: Connecting to another computer.
535 * Serial Terminal:: Connecting to a serial port.
539 @subsection Single Shell Commands
542 @findex shell-command
543 @kbd{M-!} (@code{shell-command}) reads a line of text using the
544 minibuffer and executes it as a shell command in a subshell made just
545 for that command. Standard input for the command comes from the null
546 device. If the shell command produces any output, the output appears
547 either in the echo area (if it is short), or in an Emacs buffer named
548 @samp{*Shell Command Output*}, which is displayed in another window
549 but not selected (if the output is long).
551 For instance, one way to decompress a file @file{foo.gz} from Emacs
552 is to type @kbd{M-! gunzip foo.gz @key{RET}}. That shell command
553 normally creates the file @file{foo} and produces no terminal output.
555 A numeric argument, as in @kbd{M-1 M-!}, says to insert terminal
556 output into the current buffer instead of a separate buffer. It puts
557 point before the output, and sets the mark after the output. For
558 instance, @kbd{M-1 M-! gunzip < foo.gz @key{RET}} would insert the
559 uncompressed equivalent of @file{foo.gz} into the current buffer.
561 If the shell command line ends in @samp{&}, it runs asynchronously.
562 For a synchronous shell command, @code{shell-command} returns the
563 command's exit status (0 means success), when it is called from a Lisp
564 program. You do not get any status information for an asynchronous
565 command, since it hasn't finished yet when @code{shell-command} returns.
567 You can also type @kbd{M-&} (@code{async-shell-command}) to execute
568 a shell command asynchronously. This behaves exactly like calling
569 @code{shell-command} with @samp{&}, except that you do not need to add
570 the @samp{&} to the shell command line.
573 @findex shell-command-on-region
574 @kbd{M-|} (@code{shell-command-on-region}) is like @kbd{M-!} but
575 passes the contents of the region as the standard input to the shell
576 command, instead of no input. With a numeric argument, meaning insert
577 the output in the current buffer, it deletes the old region and the
578 output replaces it as the contents of the region. It returns the
579 command's exit status, like @kbd{M-!}.
581 One use for @kbd{M-|} is to run @code{gpg} to see what keys are in
582 the buffer. For instance, if the buffer contains a GPG key, type
583 @kbd{C-x h M-| gpg @key{RET}} to feed the entire buffer contents to
584 the @code{gpg} program. That program will ignore everything except
585 the encoded keys, and will output a list of the keys the buffer
588 @vindex shell-file-name
589 Both @kbd{M-!} and @kbd{M-|} use @code{shell-file-name} to specify
590 the shell to use. This variable is initialized based on your
591 @env{SHELL} environment variable when Emacs is started. If the file
592 name is relative, Emacs searches the directories in the list
593 @code{exec-path}; this list is initialized based on the environment
594 variable @env{PATH} when Emacs is started. Your init file can
595 override either or both of these default initializations (@pxref{Init
598 Both @kbd{M-!} and @kbd{M-|} wait for the shell command to complete,
599 unless you end the command with @samp{&} to make it asynchronous. To
600 stop waiting, type @kbd{C-g} to quit; that terminates the shell
601 command with the signal @code{SIGINT}---the same signal that @kbd{C-c}
602 normally generates in the shell. Emacs then waits until the command
603 actually terminates. If the shell command doesn't stop (because it
604 ignores the @code{SIGINT} signal), type @kbd{C-g} again; this sends
605 the command a @code{SIGKILL} signal which is impossible to ignore.
607 Asynchronous commands ending in @samp{&} feed their output into
608 the buffer @samp{*Async Shell Command*}. Output arrives in that
609 buffer regardless of whether it is visible in a window.
611 To specify a coding system for @kbd{M-!} or @kbd{M-|}, use the command
612 @kbd{C-x @key{RET} c} immediately beforehand. @xref{Communication Coding}.
614 @vindex shell-command-default-error-buffer
615 Error output from these commands is normally intermixed with the
616 regular output. But if the variable
617 @code{shell-command-default-error-buffer} has a string as value, and
618 it's the name of a buffer, @kbd{M-!} and @kbd{M-|} insert error output
619 before point in that buffer.
621 @node Interactive Shell
622 @subsection Interactive Inferior Shell
625 To run a subshell interactively, use @kbd{M-x shell}. This creates
626 (or reuses) a buffer named @samp{*shell*} and runs a subshell with
627 input coming from and output going to that buffer. That is to say,
628 any ``terminal output'' from the subshell goes into the buffer,
629 advancing point, and any ``terminal input'' for the subshell comes
630 from text in the buffer. To give input to the subshell, go to the end
631 of the buffer and type the input, terminated by @key{RET}.
633 Emacs does not wait for the subshell to do anything. You can switch
634 windows or buffers and edit them while the shell is waiting, or while it is
635 running a command. Output from the subshell waits until Emacs has time to
636 process it; this happens whenever Emacs is waiting for keyboard input or
639 @cindex @code{comint-highlight-input} face
640 @cindex @code{comint-highlight-prompt} face
641 Input lines, once you submit them, are displayed using the face
642 @code{comint-highlight-input}, and prompts are displayed using the
643 face @code{comint-highlight-prompt}. This makes it easier to see
644 previous input lines in the buffer. @xref{Faces}.
646 To make multiple subshells, you can invoke @kbd{M-x shell} with a
647 prefix argument (e.g. @kbd{C-u M-x shell}), which will read a buffer
648 name and create (or reuse) a subshell in that buffer. You can also
649 rename the @samp{*shell*} buffer using @kbd{M-x rename-uniquely}, then
650 create a new @samp{*shell*} buffer using plain @kbd{M-x shell}.
651 Subshells in different buffers run independently and in parallel.
653 @vindex explicit-shell-file-name
654 @cindex environment variables for subshells
655 @cindex @env{ESHELL} environment variable
656 @cindex @env{SHELL} environment variable
657 The file name used to load the subshell is the value of the variable
658 @code{explicit-shell-file-name}, if that is non-@code{nil}.
659 Otherwise, the environment variable @env{ESHELL} is used, or the
660 environment variable @env{SHELL} if there is no @env{ESHELL}. If the
661 file name specified is relative, the directories in the list
662 @code{exec-path} are searched; this list is initialized based on the
663 environment variable @env{PATH} when Emacs is started. Your init file
664 can override either or both of these default initializations.
667 Emacs sends the new shell the contents of the file
668 @file{~/.emacs_@var{shellname}} as input, if it exists, where
669 @var{shellname} is the name of the file that the shell was loaded
670 from. For example, if you use bash, the file sent to it is
671 @file{~/.emacs_bash}. If this file is not found, Emacs tries to fallback
672 on @file{~/.emacs.d/init_@var{shellname}.sh}.
674 To specify a coding system for the shell, you can use the command
675 @kbd{C-x @key{RET} c} immediately before @kbd{M-x shell}. You can
676 also change the coding system for a running subshell by typing
677 @kbd{C-x @key{RET} p} in the shell buffer. @xref{Communication
680 @cindex @env{INSIDE_EMACS} environment variable
681 Emacs sets the environment variable @env{INSIDE_EMACS} in the
682 subshell to a comma-separated list including the Emacs version.
683 Programs can check this variable to determine whether they are running
684 inside an Emacs subshell.
686 @cindex @env{EMACS} environment variable
687 Emacs also sets the @env{EMACS} environment variable (to @code{t}) if
688 it is not already defined. @strong{Warning:} This environment
689 variable is deprecated. Programs that check this variable should be
690 changed to check @env{INSIDE_EMACS} instead.
693 @subsection Shell Mode
697 Shell buffers use Shell mode, which defines several special keys
698 attached to the @kbd{C-c} prefix. They are chosen to resemble the usual
699 editing and job control characters present in shells that are not under
700 Emacs, except that you must type @kbd{C-c} first. Here is a complete list
701 of the special key bindings of Shell mode:
705 @kindex RET @r{(Shell mode)}
706 @findex comint-send-input
707 At end of buffer send line as input; otherwise, copy current line to
708 end of buffer and send it (@code{comint-send-input}). Copying a line
709 in this way omits any prompt at the beginning of the line (text output
710 by programs preceding your input). @xref{Shell Prompts}, for how
711 Shell mode recognizes prompts.
714 @kindex TAB @r{(Shell mode)}
715 @findex comint-dynamic-complete
716 Complete the command name or file name before point in the shell buffer
717 (@code{comint-dynamic-complete}). @key{TAB} also completes history
718 references (@pxref{History References}) and environment variable names.
720 @vindex shell-completion-fignore
721 @vindex comint-completion-fignore
722 The variable @code{shell-completion-fignore} specifies a list of file
723 name extensions to ignore in Shell mode completion. The default
724 setting is @code{nil}, but some users prefer @code{("~" "#" "%")} to
725 ignore file names ending in @samp{~}, @samp{#} or @samp{%}. Other
726 related Comint modes use the variable @code{comint-completion-fignore}
730 @kindex M-? @r{(Shell mode)}
731 @findex comint-dynamic-list-filename@dots{}
732 Display temporarily a list of the possible completions of the file name
733 before point in the shell buffer
734 (@code{comint-dynamic-list-filename-completions}).
737 @kindex C-d @r{(Shell mode)}
738 @findex comint-delchar-or-maybe-eof
739 Either delete a character or send @acronym{EOF}
740 (@code{comint-delchar-or-maybe-eof}). Typed at the end of the shell
741 buffer, @kbd{C-d} sends @acronym{EOF} to the subshell. Typed at any other
742 position in the buffer, @kbd{C-d} deletes a character as usual.
745 @kindex C-c C-a @r{(Shell mode)}
746 @findex comint-bol-or-process-mark
747 Move to the beginning of the line, but after the prompt if any
748 (@code{comint-bol-or-process-mark}). If you repeat this command twice
749 in a row, the second time it moves back to the process mark, which is
750 the beginning of the input that you have not yet sent to the subshell.
751 (Normally that is the same place---the end of the prompt on this
752 line---but after @kbd{C-c @key{SPC}} the process mark may be in a
756 Accumulate multiple lines of input, then send them together. This
757 command inserts a newline before point, but does not send the preceding
758 text as input to the subshell---at least, not yet. Both lines, the one
759 before this newline and the one after, will be sent together (along with
760 the newline that separates them), when you type @key{RET}.
763 @kindex C-c C-u @r{(Shell mode)}
764 @findex comint-kill-input
765 Kill all text pending at end of buffer to be sent as input
766 (@code{comint-kill-input}). If point is not at end of buffer,
767 this only kills the part of this text that precedes point.
770 @kindex C-c C-w @r{(Shell mode)}
771 Kill a word before point (@code{backward-kill-word}).
774 @kindex C-c C-c @r{(Shell mode)}
775 @findex comint-interrupt-subjob
776 Interrupt the shell or its current subjob if any
777 (@code{comint-interrupt-subjob}). This command also kills
778 any shell input pending in the shell buffer and not yet sent.
781 @kindex C-c C-z @r{(Shell mode)}
782 @findex comint-stop-subjob
783 Stop the shell or its current subjob if any (@code{comint-stop-subjob}).
784 This command also kills any shell input pending in the shell buffer and
788 @findex comint-quit-subjob
789 @kindex C-c C-\ @r{(Shell mode)}
790 Send quit signal to the shell or its current subjob if any
791 (@code{comint-quit-subjob}). This command also kills any shell input
792 pending in the shell buffer and not yet sent.
795 @kindex C-c C-o @r{(Shell mode)}
796 @findex comint-delete-output
797 Delete the last batch of output from a shell command
798 (@code{comint-delete-output}). This is useful if a shell command spews
799 out lots of output that just gets in the way.
802 @kindex C-c C-s @r{(Shell mode)}
803 @findex comint-write-output
804 Write the last batch of output from a shell command to a file
805 (@code{comint-write-output}). With a prefix argument, the file is
806 appended to instead. Any prompt at the end of the output is not
811 @kindex C-c C-r @r{(Shell mode)}
812 @kindex C-M-l @r{(Shell mode)}
813 @findex comint-show-output
814 Scroll to display the beginning of the last batch of output at the top
815 of the window; also move the cursor there (@code{comint-show-output}).
818 @kindex C-c C-e @r{(Shell mode)}
819 @findex comint-show-maximum-output
820 Scroll to put the end of the buffer at the bottom of the window
821 (@code{comint-show-maximum-output}).
824 @kindex C-c C-f @r{(Shell mode)}
825 @findex shell-forward-command
826 @vindex shell-command-regexp
827 Move forward across one shell command, but not beyond the current line
828 (@code{shell-forward-command}). The variable @code{shell-command-regexp}
829 specifies how to recognize the end of a command.
832 @kindex C-c C-b @r{(Shell mode)}
833 @findex shell-backward-command
834 Move backward across one shell command, but not beyond the current line
835 (@code{shell-backward-command}).
838 Ask the shell what its current directory is, so that Emacs can agree
841 @item M-x send-invisible @key{RET} @var{text} @key{RET}
842 @findex send-invisible
843 Send @var{text} as input to the shell, after reading it without
844 echoing. This is useful when a shell command runs a program that asks
847 Please note that Emacs will not echo passwords by default. If you
848 really want them to be echoed, evaluate the following Lisp
852 (remove-hook 'comint-output-filter-functions
853 'comint-watch-for-password-prompt)
856 @item M-x comint-continue-subjob
857 @findex comint-continue-subjob
858 Continue the shell process. This is useful if you accidentally suspend
859 the shell process.@footnote{You should not suspend the shell process.
860 Suspending a subjob of the shell is a completely different matter---that
861 is normal practice, but you must use the shell to continue the subjob;
862 this command won't do it.}
864 @item M-x comint-strip-ctrl-m
865 @findex comint-strip-ctrl-m
866 Discard all control-M characters from the current group of shell output.
867 The most convenient way to use this command is to make it run
868 automatically when you get output from the subshell. To do that,
869 evaluate this Lisp expression:
872 (add-hook 'comint-output-filter-functions
873 'comint-strip-ctrl-m)
876 @item M-x comint-truncate-buffer
877 @findex comint-truncate-buffer
878 This command truncates the shell buffer to a certain maximum number of
879 lines, specified by the variable @code{comint-buffer-maximum-size}.
880 Here's how to do this automatically each time you get output from the
884 (add-hook 'comint-output-filter-functions
885 'comint-truncate-buffer)
891 Shell mode is a derivative of Comint mode, a general-purpose mode for
892 communicating with interactive subprocesses. Most of the features of
893 Shell mode actually come from Comint mode, as you can see from the
894 command names listed above. The special features of Shell mode include
895 the directory tracking feature, and a few user commands.
897 Other Emacs features that use variants of Comint mode include GUD
898 (@pxref{Debuggers}) and @kbd{M-x run-lisp} (@pxref{External Lisp}).
901 You can use @kbd{M-x comint-run} to execute any program of your choice
902 in a subprocess using unmodified Comint mode---without the
903 specializations of Shell mode.
906 @subsection Shell Prompts
908 @vindex shell-prompt-pattern
909 @vindex comint-prompt-regexp
910 @vindex comint-use-prompt-regexp
911 @cindex prompt, shell
912 A prompt is text output by a program to show that it is ready to
913 accept new user input. Normally, Comint mode (and thus Shell mode)
914 considers the prompt to be any text output by a program at the
915 beginning of an input line. However, if the variable
916 @code{comint-use-prompt-regexp} is non-@code{nil}, then Comint mode
917 uses a regular expression to recognize prompts. In Shell mode,
918 @code{shell-prompt-pattern} specifies the regular expression.
920 The value of @code{comint-use-prompt-regexp} also affects many
921 motion and paragraph commands. If the value is non-@code{nil}, the
922 general Emacs motion commands behave as they normally do in buffers
923 without special text properties. However, if the value is @code{nil},
924 the default, then Comint mode divides the buffer into two types of
925 ``fields'' (ranges of consecutive characters having the same
926 @code{field} text property): input and output. Prompts are part of
927 the output. Most Emacs motion commands do not cross field boundaries,
928 unless they move over multiple lines. For instance, when point is in
929 input on the same line as a prompt, @kbd{C-a} puts point at the
930 beginning of the input if @code{comint-use-prompt-regexp} is
931 @code{nil} and at the beginning of the line otherwise.
933 In Shell mode, only shell prompts start new paragraphs. Thus, a
934 paragraph consists of a prompt and the input and output that follow
935 it. However, if @code{comint-use-prompt-regexp} is @code{nil}, the
936 default, most paragraph commands do not cross field boundaries. This
937 means that prompts, ranges of input, and ranges of non-prompt output
938 behave mostly like separate paragraphs; with this setting, numeric
939 arguments to most paragraph commands yield essentially undefined
940 behavior. For the purpose of finding paragraph boundaries, Shell mode
941 uses @code{shell-prompt-pattern}, regardless of
942 @code{comint-use-prompt-regexp}.
945 @subsection Shell Command History
947 Shell buffers support three ways of repeating earlier commands. You
948 can use keys like those used for the minibuffer history; these work
949 much as they do in the minibuffer, inserting text from prior commands
950 while point remains always at the end of the buffer. You can move
951 through the buffer to previous inputs in their original place, then
952 resubmit them or copy them to the end. Or you can use a
953 @samp{!}-style history reference.
956 * Ring: Shell Ring. Fetching commands from the history list.
957 * Copy: Shell History Copying. Moving to a command and then copying it.
958 * History References:: Expanding @samp{!}-style history references.
962 @subsubsection Shell History Ring
965 @findex comint-previous-input
966 @kindex M-p @r{(Shell mode)}
969 Fetch the next earlier old shell command.
971 @kindex M-n @r{(Shell mode)}
972 @findex comint-next-input
975 Fetch the next later old shell command.
977 @kindex M-r @r{(Shell mode)}
978 @findex comint-history-isearch-backward-regexp
980 Begin an incremental regexp search of old shell commands.
983 @kindex C-c C-x @r{(Shell mode)}
984 @findex comint-get-next-from-history
985 Fetch the next subsequent command from the history.
988 @kindex C-c . @r{(Shell mode)}
989 @findex comint-input-previous-argument
990 Fetch one argument from an old shell command.
993 @kindex C-c C-l @r{(Shell mode)}
994 @findex comint-dynamic-list-input-ring
995 Display the buffer's history of shell commands in another window
996 (@code{comint-dynamic-list-input-ring}).
999 Shell buffers provide a history of previously entered shell commands. To
1000 reuse shell commands from the history, use the editing commands @kbd{M-p},
1001 @kbd{M-n}, @kbd{M-r} and @kbd{M-s}. These work just like the minibuffer
1002 history commands except that they operate on the text at the end of the
1003 shell buffer, where you would normally insert text to send to the shell.
1005 @kbd{M-p} fetches an earlier shell command to the end of the shell
1006 buffer. Successive use of @kbd{M-p} fetches successively earlier
1007 shell commands, each replacing any text that was already present as
1008 potential shell input. @kbd{M-n} does likewise except that it finds
1009 successively more recent shell commands from the buffer.
1010 @kbd{C-@key{UP}} works like @kbd{M-p}, and @kbd{C-@key{DOWN}} like
1013 The history search command @kbd{M-r} begins an incremental regular
1014 expression search of previous shell commands. After typing @kbd{M-r},
1015 start typing the desired string or regular expression; the last
1016 matching shell command will be displayed in the current line.
1017 Incremental search commands have their usual effects---for instance,
1018 @kbd{C-s} and @kbd{C-r} search forward and backward for the next match
1019 (@pxref{Incremental Search}). When you find the desired input, type
1020 @key{RET} to terminate the search. This puts the input in the command
1021 line. Any partial input you were composing before navigating the
1022 history list is restored when you go to the beginning or end of the
1025 Often it is useful to reexecute several successive shell commands that
1026 were previously executed in sequence. To do this, first find and
1027 reexecute the first command of the sequence. Then type @kbd{C-c C-x};
1028 that will fetch the following command---the one that follows the command
1029 you just repeated. Then type @key{RET} to reexecute this command. You
1030 can reexecute several successive commands by typing @kbd{C-c C-x
1031 @key{RET}} over and over.
1033 The command @kbd{C-c .}@: (@code{comint-input-previous-argument})
1034 copies an individual argument from a previous command, like @kbd{ESC
1035 .} in Bash. The simplest use copies the last argument from the
1036 previous shell command. With a prefix argument @var{n}, it copies the
1037 @var{n}th argument instead. Repeating @kbd{C-c .} copies from an
1038 earlier shell command instead, always using the same value of @var{n}
1039 (don't give a prefix argument when you repeat the @kbd{C-c .}
1042 These commands get the text of previous shell commands from a special
1043 history list, not from the shell buffer itself. Thus, editing the shell
1044 buffer, or even killing large parts of it, does not affect the history
1045 that these commands access.
1047 @vindex shell-input-ring-file-name
1048 Some shells store their command histories in files so that you can
1049 refer to commands from previous shell sessions. Emacs reads
1050 the command history file for your chosen shell, to initialize its own
1051 command history. The file name is @file{~/.bash_history} for bash,
1052 @file{~/.sh_history} for ksh, and @file{~/.history} for other shells.
1054 @node Shell History Copying
1055 @subsubsection Shell History Copying
1058 @kindex C-c C-p @r{(Shell mode)}
1059 @findex comint-previous-prompt
1061 Move point to the previous prompt (@code{comint-previous-prompt}).
1063 @kindex C-c C-n @r{(Shell mode)}
1064 @findex comint-next-prompt
1066 Move point to the following prompt (@code{comint-next-prompt}).
1068 @kindex C-c RET @r{(Shell mode)}
1069 @findex comint-copy-old-input
1071 Copy the input command at point, inserting the copy at the end of the
1072 buffer (@code{comint-copy-old-input}). This is useful if you move
1073 point back to a previous command. After you copy the command, you can
1074 submit the copy as input with @key{RET}. If you wish, you can edit
1075 the copy before resubmitting it. If you use this command on an output
1076 line, it copies that line to the end of the buffer.
1079 If @code{comint-use-prompt-regexp} is @code{nil} (the default), copy
1080 the old input command that you click on, inserting the copy at the end
1081 of the buffer (@code{comint-insert-input}). If
1082 @code{comint-use-prompt-regexp} is non-@code{nil}, or if the click is
1083 not over old input, just yank as usual.
1086 Moving to a previous input and then copying it with @kbd{C-c
1087 @key{RET}} or @kbd{Mouse-2} produces the same results---the same
1088 buffer contents---that you would get by using @kbd{M-p} enough times
1089 to fetch that previous input from the history list. However, @kbd{C-c
1090 @key{RET}} copies the text from the buffer, which can be different
1091 from what is in the history list if you edit the input text in the
1092 buffer after it has been sent.
1094 @node History References
1095 @subsubsection Shell History References
1096 @cindex history reference
1098 Various shells including csh and bash support @dfn{history
1099 references} that begin with @samp{!} and @samp{^}. Shell mode
1100 recognizes these constructs, and can perform the history substitution
1103 If you insert a history reference and type @key{TAB}, this searches
1104 the input history for a matching command, performs substitution if
1105 necessary, and places the result in the buffer in place of the history
1106 reference. For example, you can fetch the most recent command
1107 beginning with @samp{mv} with @kbd{! m v @key{TAB}}. You can edit the
1108 command if you wish, and then resubmit the command to the shell by
1111 @vindex comint-input-autoexpand
1112 @findex comint-magic-space
1113 Shell mode can optionally expand history references in the buffer
1114 when you send them to the shell. To request this, set the variable
1115 @code{comint-input-autoexpand} to @code{input}. You can make
1116 @key{SPC} perform history expansion by binding @key{SPC} to the
1117 command @code{comint-magic-space}.
1119 Shell mode recognizes history references when they follow a prompt.
1120 @xref{Shell Prompts}, for how Shell mode recognizes prompts.
1122 @node Directory Tracking
1123 @subsection Directory Tracking
1124 @cindex directory tracking
1126 @vindex shell-pushd-regexp
1127 @vindex shell-popd-regexp
1128 @vindex shell-cd-regexp
1129 Shell mode keeps track of @samp{cd}, @samp{pushd} and @samp{popd}
1130 commands given to the inferior shell, so it can keep the
1131 @samp{*shell*} buffer's default directory the same as the shell's
1132 working directory. It recognizes these commands syntactically, by
1133 examining lines of input that are sent.
1135 If you use aliases for these commands, you can tell Emacs to
1136 recognize them also. For example, if the value of the variable
1137 @code{shell-pushd-regexp} matches the beginning of a shell command
1138 line, that line is regarded as a @code{pushd} command. Change this
1139 variable when you add aliases for @samp{pushd}. Likewise,
1140 @code{shell-popd-regexp} and @code{shell-cd-regexp} are used to
1141 recognize commands with the meaning of @samp{popd} and @samp{cd}.
1142 These commands are recognized only at the beginning of a shell command
1145 @ignore @c This seems to have been deleted long ago.
1146 @vindex shell-set-directory-error-hook
1147 If Emacs gets an error while trying to handle what it believes is a
1148 @samp{cd}, @samp{pushd} or @samp{popd} command, it runs the hook
1149 @code{shell-set-directory-error-hook} (@pxref{Hooks}).
1153 If Emacs gets confused about changes in the current directory of the
1154 subshell, use the command @kbd{M-x dirs} to ask the shell what its
1155 current directory is. This command works for shells that support the
1156 most common command syntax; it may not work for unusual shells.
1158 @findex dirtrack-mode
1159 You can also use @kbd{M-x dirtrack-mode} to enable (or disable) an
1160 alternative method of tracking changes in the current directory. This
1161 method relies on your shell prompt containing the full current working
1162 directory at all times.
1165 @subsection Shell Mode Options
1167 @vindex comint-scroll-to-bottom-on-input
1168 If the variable @code{comint-scroll-to-bottom-on-input} is
1169 non-@code{nil}, insertion and yank commands scroll the selected window
1170 to the bottom before inserting. The default is @code{nil}.
1172 @vindex comint-scroll-show-maximum-output
1173 If @code{comint-scroll-show-maximum-output} is non-@code{nil}, then
1174 arrival of output when point is at the end tries to scroll the last
1175 line of text to the bottom line of the window, showing as much useful
1176 text as possible. (This mimics the scrolling behavior of most
1177 terminals.) The default is @code{t}.
1179 @vindex comint-move-point-for-output
1180 By setting @code{comint-move-point-for-output}, you can opt for
1181 having point jump to the end of the buffer whenever output arrives---no
1182 matter where in the buffer point was before. If the value is
1183 @code{this}, point jumps in the selected window. If the value is
1184 @code{all}, point jumps in each window that shows the Comint buffer. If
1185 the value is @code{other}, point jumps in all nonselected windows that
1186 show the current buffer. The default value is @code{nil}, which means
1187 point does not jump to the end.
1189 @vindex comint-prompt-read-only
1190 If you set @code{comint-prompt-read-only}, the prompts in the Comint
1191 buffer are read-only.
1193 @vindex comint-input-ignoredups
1194 The variable @code{comint-input-ignoredups} controls whether successive
1195 identical inputs are stored in the input history. A non-@code{nil}
1196 value means to omit an input that is the same as the previous input.
1197 The default is @code{nil}, which means to store each input even if it is
1198 equal to the previous input.
1200 @vindex comint-completion-addsuffix
1201 @vindex comint-completion-recexact
1202 @vindex comint-completion-autolist
1203 Three variables customize file name completion. The variable
1204 @code{comint-completion-addsuffix} controls whether completion inserts a
1205 space or a slash to indicate a fully completed file or directory name
1206 (non-@code{nil} means do insert a space or slash).
1207 @code{comint-completion-recexact}, if non-@code{nil}, directs @key{TAB}
1208 to choose the shortest possible completion if the usual Emacs completion
1209 algorithm cannot add even a single character.
1210 @code{comint-completion-autolist}, if non-@code{nil}, says to list all
1211 the possible completions whenever completion is not exact.
1213 @vindex shell-completion-execonly
1214 Command completion normally considers only executable files.
1215 If you set @code{shell-completion-execonly} to @code{nil},
1216 it considers nonexecutable files as well.
1218 @findex shell-pushd-tohome
1219 @findex shell-pushd-dextract
1220 @findex shell-pushd-dunique
1221 You can configure the behavior of @samp{pushd}. Variables control
1222 whether @samp{pushd} behaves like @samp{cd} if no argument is given
1223 (@code{shell-pushd-tohome}), pop rather than rotate with a numeric
1224 argument (@code{shell-pushd-dextract}), and only add directories to the
1225 directory stack if they are not already on it
1226 (@code{shell-pushd-dunique}). The values you choose should match the
1227 underlying shell, of course.
1229 @node Terminal emulator
1230 @subsection Emacs Terminal Emulator
1233 To run a subshell in a terminal emulator, use @kbd{M-x term}. This
1234 creates (or reuses) a buffer named @samp{*terminal*}, and runs a
1235 subshell with input coming from your keyboard, and output going to
1238 The terminal emulator uses Term mode, which has two input modes. In
1239 line mode, Term basically acts like Shell mode; see @ref{Shell Mode}.
1241 In char mode, each character is sent directly to the inferior
1242 subshell, as ``terminal input.'' Any ``echoing'' of your input is the
1243 responsibility of the subshell. The sole exception is the terminal
1244 escape character, which by default is @kbd{C-c} (@pxref{Term Mode}).
1245 Any ``terminal output'' from the subshell goes into the buffer,
1248 Some programs (such as Emacs itself) need to control the appearance
1249 on the terminal screen in detail. They do this by sending special
1250 control codes. The exact control codes needed vary from terminal to
1251 terminal, but nowadays most terminals and terminal emulators
1252 (including @code{xterm}) understand the ANSI-standard (VT100-style)
1253 escape sequences. Term mode recognizes these escape sequences, and
1254 handles each one appropriately, changing the buffer so that the
1255 appearance of the window matches what it would be on a real terminal.
1256 You can actually run Emacs inside an Emacs Term window.
1258 You can use Term mode to communicate with a device connected to a
1259 serial port of your computer. @xref{Serial Terminal}.
1261 The file name used to load the subshell is determined the same way
1262 as for Shell mode. To make multiple terminal emulators, rename the
1263 buffer @samp{*terminal*} to something different using @kbd{M-x
1264 rename-uniquely}, just as with Shell mode.
1266 Unlike Shell mode, Term mode does not track the current directory by
1267 examining your input. But some shells can tell Term what the current
1268 directory is. This is done automatically by @code{bash} version 1.15
1272 @subsection Term Mode
1276 The terminal emulator uses Term mode, which has two input modes. In
1277 line mode, Term basically acts like Shell mode; see @ref{Shell Mode}.
1278 In char mode, each character is sent directly to the inferior
1279 subshell, except for the Term escape character, normally @kbd{C-c}.
1281 To switch between line and char mode, use these commands:
1284 @kindex C-c C-j @r{(Term mode)}
1285 @findex term-char-mode
1287 Switch to line mode. Do nothing if already in line mode.
1289 @kindex C-c C-k @r{(Term mode)}
1290 @findex term-line-mode
1292 Switch to char mode. Do nothing if already in char mode.
1295 The following commands are only available in char mode:
1299 Send a literal @key{C-c} to the sub-shell.
1301 @item C-c @var{char}
1302 This is equivalent to @kbd{C-x @var{char}} in normal Emacs. For
1303 example, @kbd{C-c o} invokes the global binding of @kbd{C-x o}, which
1304 is normally @samp{other-window}.
1307 @node Paging in Term
1308 @subsection Page-At-A-Time Output
1309 @cindex page-at-a-time
1311 Term mode has a page-at-a-time feature. When enabled it makes
1312 output pause at the end of each screenful.
1315 @kindex C-c C-q @r{(Term mode)}
1316 @findex term-pager-toggle
1318 Toggle the page-at-a-time feature. This command works in both line
1319 and char modes. When page-at-a-time is enabled, the mode-line
1320 displays the word @samp{page}.
1323 With page-at-a-time enabled, whenever Term receives more than a
1324 screenful of output since your last input, it pauses, displaying
1325 @samp{**MORE**} in the mode-line. Type @key{SPC} to display the next
1326 screenful of output. Type @kbd{?} to see your other options. The
1327 interface is similar to the @code{more} program.
1330 @subsection Remote Host Shell
1332 @cindex connecting to remote host
1336 You can login to a remote computer, using whatever commands you
1337 would from a regular terminal (e.g.@: using the @code{telnet} or
1338 @code{rlogin} commands), from a Term window.
1340 A program that asks you for a password will normally suppress
1341 echoing of the password, so the password will not show up in the
1342 buffer. This will happen just as if you were using a real terminal,
1343 if the buffer is in char mode. If it is in line mode, the password is
1344 temporarily visible, but will be erased when you hit return. (This
1345 happens automatically; there is no special password processing.)
1347 When you log in to a different machine, you need to specify the type
1348 of terminal you're using, by setting the @env{TERM} environment
1349 variable in the environment for the remote login command. (If you use
1350 bash, you do that by writing the variable assignment before the remote
1351 login command, without separating comma.) Terminal types @samp{ansi}
1352 or @samp{vt100} will work on most systems.
1354 @c If you are talking to a Bourne-compatible
1355 @c shell, and your system understands the @env{TERMCAP} variable,
1356 @c you can use the command @kbd{M-x shell-send-termcap}, which
1357 @c sends a string specifying the terminal type and size.
1358 @c (This command is also useful after the window has changed size.)
1360 @c You can of course run @samp{gdb} on that remote computer. One useful
1361 @c trick: If you invoke gdb with the @code{--fullname} option,
1362 @c it will send special commands to Emacs that will cause Emacs to
1363 @c pop up the source files you're debugging. This will work
1364 @c whether or not gdb is running on a different computer than Emacs,
1365 @c as long as Emacs can access the source files specified by gdb.
1368 You cannot log in to a remote computer using the Shell mode.
1369 @c (This will change when Shell is re-written to use Term.)
1370 Instead, Emacs provides two commands for logging in to another computer
1371 and communicating with it through an Emacs buffer using Comint mode:
1374 @item M-x telnet @key{RET} @var{hostname} @key{RET}
1375 Set up a Telnet connection to the computer named @var{hostname}.
1376 @item M-x rlogin @key{RET} @var{hostname} @key{RET}
1377 Set up an Rlogin connection to the computer named @var{hostname}.
1381 Use @kbd{M-x telnet} to set up a Telnet connection to another
1382 computer. (Telnet is the standard Internet protocol for remote login.)
1383 It reads the host name of the other computer as an argument with the
1384 minibuffer. Once the connection is established, talking to the other
1385 computer works like talking to a subshell: you can edit input with the
1386 usual Emacs commands, and send it a line at a time by typing @key{RET}.
1387 The output is inserted in the Telnet buffer interspersed with the input.
1390 @vindex rlogin-explicit-args
1391 Use @kbd{M-x rlogin} to set up an Rlogin connection. Rlogin is
1392 another remote login communication protocol, essentially much like the
1393 Telnet protocol but incompatible with it, and supported only by certain
1394 systems. Rlogin's advantages are that you can arrange not to have to
1395 give your user name and password when communicating between two machines
1396 you frequently use, and that you can make an 8-bit-clean connection.
1397 (To do that in Emacs, set @code{rlogin-explicit-args} to @code{("-8")}
1398 before you run Rlogin.)
1400 @kbd{M-x rlogin} sets up the default file directory of the Emacs
1401 buffer to access the remote host via FTP (@pxref{File Names}), and it
1402 tracks the shell commands that change the current directory, just like
1405 @findex rlogin-directory-tracking-mode
1406 There are two ways of doing directory tracking in an Rlogin
1407 buffer---either with remote directory names
1408 @file{/@var{host}:@var{dir}/} or with local names (that works if the
1409 ``remote'' machine shares file systems with your machine of origin).
1410 You can use the command @code{rlogin-directory-tracking-mode} to switch
1411 modes. No argument means use remote directory names, a positive
1412 argument means use local names, and a negative argument means turn
1413 off directory tracking.
1417 @node Serial Terminal
1418 @subsection Serial Terminal
1419 @cindex terminal, serial
1422 If you have a device connected to a serial port of your computer,
1423 you can use Emacs to communicate with it. @kbd{M-x serial-term} will
1424 ask you for a serial port name and speed and will then open a new
1425 window in @ref{Term Mode}.
1427 The speed of the serial port is measured in bits per second. The
1428 most common speed is 9600 bits per second. You can change the speed
1429 interactively by clicking on the mode line.
1431 A serial port can be configured even more by clicking on ``8N1'' in
1432 the mode line. By default, a serial port is configured as ``8N1'',
1433 which means that each byte consists of 8 data bits, No parity check
1436 When you have opened the serial port connection, you will see output
1437 from the device in the window. Also, what you type in the window is
1440 If the speed or the configuration is wrong, you cannot communicate
1441 with your device and will probably only see garbage output in the
1444 @node Emacs Server, Printing, Shell, Top
1445 @section Using Emacs as a Server
1447 @cindex Emacs as a server
1448 @cindex server, using Emacs as
1449 @cindex @env{EDITOR} environment variable
1451 Various programs such as @command{mail} can invoke your choice of
1452 editor to edit a particular piece of text, such as a message that you
1453 are sending. By convention, most of these programs use the
1454 environment variable @env{EDITOR} to specify which editor to run. If
1455 you set @env{EDITOR} to @samp{emacs}, they invoke Emacs---but in an
1456 inconvenient way, by starting a new Emacs process. This is
1457 inconvenient because the new Emacs process doesn't share buffers, a
1458 command history, or other kinds of information with any existing Emacs
1461 You can solve this problem by setting up Emacs as an @dfn{edit
1462 server}, so that it ``listens'' for external edit requests and acts
1463 accordingly. There are two ways to start an Emacs server:
1465 @findex server-start
1466 The first is to run the command @code{server-start} in an existing
1467 Emacs process: either type @kbd{M-x server-start}, or put the
1468 expression @code{(server-start)} in your initialization file
1469 (@pxref{Init File}). The existing Emacs process is the server; when
1470 you exit Emacs, the server dies with the Emacs process.
1472 @cindex daemon, Emacs
1473 The second way to start an Emacs server is to run Emacs as a
1474 @dfn{daemon}, using the @samp{--daemon} command-line option.
1475 @xref{Initial Options}. When Emacs is started this way, it calls
1476 @code{server-start} after initialization, and returns control to the
1477 calling terminal instead of opening an initial frame; it then waits in
1478 the background, listening for edit requests.
1480 @cindex @env{TEXEDIT} environment variable
1481 Once an Emacs server is set up, you can use a shell command called
1482 @command{emacsclient} to connect to the existing Emacs process and
1483 tell it to visit a file. If you set the @env{EDITOR} environment
1484 variable to @samp{emacsclient}, programs such as @command{mail} will
1485 use the existing Emacs process for editing.@footnote{Some programs use
1486 a different environment variable; for example, to make @TeX{} use
1487 @samp{emacsclient}, set the @env{TEXEDIT} environment variable to
1488 @samp{emacsclient +%d %s}.}
1491 You can run multiple Emacs servers on the same machine by giving
1492 each one a unique ``server name'', using the variable
1493 @code{server-name}. For example, @kbd{M-x set-variable @key{RET}
1494 server-name @key{RET} foo @key{RET}} sets the server name to
1495 @samp{foo}. The @code{emacsclient} program can specify a server by
1496 name, using the @samp{-s} option (@pxref{emacsclient Options}).
1498 @findex server-eval-at
1499 If you have defined a server by a unique server name, you can
1500 connect to this server from other Emacs instances and evaluate forms
1501 on it by using the @code{server-eval-at} function.
1503 @code{(server-eval-at "foo" '(+ 1 2))} gives the result @code{3}, if
1504 there's a server with that name that is listening. If not, an error
1508 * Invoking emacsclient:: Connecting to the Emacs server.
1509 * emacsclient Options:: Emacs client startup options.
1512 @node Invoking emacsclient
1513 @subsection Invoking @code{emacsclient}
1514 @cindex @code{emacsclient} invocation
1516 The simplest way to use the @command{emacsclient} program is to run
1517 the shell command @samp{emacsclient @var{file}}, where @var{file} is a
1518 file name. This connects to an Emacs server, and tells that Emacs
1519 process to visit @var{file} in one of its existing frames---either a
1520 graphical frame, or one in a text-only terminal (@pxref{Frames}). You
1521 can then select that frame to begin editing.
1523 If there is no Emacs server, the @command{emacsclient} program halts
1524 with an error message. If the Emacs process has no existing
1525 frame---which can happen if it was started as a daemon (@pxref{Emacs
1526 Server})---then Emacs opens a frame on the terminal in which you
1527 called @command{emacsclient}.
1529 You can also force @command{emacsclient} to open a new frame on a
1530 graphical display, or on a text-only terminal, using the @samp{-c} and
1531 @samp{-t} options. @xref{emacsclient Options}.
1533 If you are running on a single text-only terminal, you can switch
1534 between @command{emacsclient}'s shell and the Emacs server using one
1535 of two methods: (i) run the Emacs server and @command{emacsclient} on
1536 different virtual terminals, and switch to the Emacs server's virtual
1537 terminal after calling @command{emacsclient}; or (ii) call
1538 @command{emacsclient} from within the Emacs server itself, using Shell
1539 mode (@pxref{Interactive Shell}) or Term mode (@pxref{Term Mode});
1540 @code{emacsclient} blocks only the subshell under Emacs, and you can
1541 still use Emacs to edit the file.
1545 When you finish editing @var{file} in the Emacs server, type
1546 @kbd{C-x #} (@code{server-edit}) in its buffer. This saves the file
1547 and sends a message back to the @command{emacsclient} program, telling
1548 it to exit. Programs that use @env{EDITOR} usually wait for the
1549 ``editor''---in this case @command{emacsclient}---to exit before doing
1552 You can also call @command{emacsclient} with multiple file name
1553 arguments: @samp{emacsclient @var{file1} @var{file2} ...} tells the
1554 Emacs server to visit @var{file1}, @var{file2}, and so forth. Emacs
1555 selects the buffer visiting @var{file1}, and buries the other buffers
1556 at the bottom of the buffer list (@pxref{Buffers}). The
1557 @command{emacsclient} program exits once all the specified files are
1558 finished (i.e., once you have typed @kbd{C-x #} in each server
1561 @vindex server-kill-new-buffers
1562 @vindex server-temp-file-regexp
1563 Finishing with a server buffer also kills the buffer, unless it
1564 already existed in the Emacs session before the server was asked to
1565 create it. However, if you set @code{server-kill-new-buffers} to
1566 @code{nil}, then a different criterion is used: finishing with a
1567 server buffer kills it if the file name matches the regular expression
1568 @code{server-temp-file-regexp}. This is set up to distinguish certain
1569 ``temporary'' files.
1571 Each @kbd{C-x #} checks for other pending external requests to edit
1572 various files, and selects the next such file. You can switch to a
1573 server buffer manually if you wish; you don't have to arrive at it
1574 with @kbd{C-x #}. But @kbd{C-x #} is the way to tell
1575 @command{emacsclient} that you are finished.
1577 @vindex server-window
1578 If you set the value of the variable @code{server-window} to a
1579 window or a frame, @kbd{C-x #} always displays the next server buffer
1580 in that window or in that frame.
1582 @node emacsclient Options
1583 @subsection @code{emacsclient} Options
1584 @cindex @code{emacsclient} options
1586 You can pass some optional arguments to the @command{emacsclient}
1590 emacsclient -c +12 @var{file1} +4:3 @var{file2}
1594 The @samp{+@var{line}} or @samp{+@var{line}:@var{column}} arguments
1595 specify line numbers, or line and column numbers, for the next file
1596 argument. These behave like the command line arguments for Emacs
1597 itself. @xref{Action Arguments}.
1599 The other optional arguments recognized by @command{emacsclient} are
1603 @item -a @var{command}
1604 @itemx --alternate-editor=@var{command}
1605 Specify a command to run if @code{emacsclient} fails to contact Emacs.
1606 This is useful when running @code{emacsclient} in a script.
1608 As a special exception, if @var{command} is the empty string, then
1609 @code{emacsclient} starts Emacs in daemon mode and then tries
1612 @cindex @env{ALTERNATE_EDITOR} environment variable
1613 The environment variable @env{ALTERNATE_EDITOR} has the same effect as
1614 the @samp{-a} option. If both are present, the latter takes
1618 Create a new graphical frame, instead of using an existing Emacs
1619 frame. Emacs 23 can create a graphical frame even if it was started
1620 in a text-only terminal, provided it is able to connect to a graphical
1621 display. If no graphical display is available, Emacs creates a new
1622 text-only terminal frame (@pxref{Frames}). If you omit a filename
1623 argument while supplying the @samp{-c} option, the new frame displays
1624 the @samp{*scratch*} buffer (@pxref{Buffers}).
1627 @itemx --frame-parameters=@var{alist}
1628 Set the parameters for a newly-created graphical frame
1629 (@pxref{Frame Parameters}).
1631 @item -d @var{display}
1632 @itemx --display=@var{display}
1633 Tell Emacs to open the given files on the X display @var{display}
1634 (assuming there is more than one X display available).
1638 Tell Emacs to evaluate some Emacs Lisp code, instead of visiting some
1639 files. When this option is given, the arguments to
1640 @command{emacsclient} are interpreted as a list of expressions to
1641 evaluate, @emph{not} as a list of files to visit.
1643 @item -f @var{server-file}
1644 @itemx --server-file=@var{server-file}
1645 @cindex @env{EMACS_SERVER_FILE} environment variable
1647 @vindex server-use-tcp
1649 Specify a @dfn{server file} for connecting to an Emacs server via TCP.
1651 An Emacs server usually uses an operating system feature called a
1652 ``local socket'' to listen for connections. Some operating systems,
1653 such as Microsoft Windows, do not support local sockets; in that case,
1654 Emacs uses TCP instead. When you start the Emacs server, Emacs
1655 creates a server file containing some TCP information that
1656 @command{emacsclient} needs for making the connection. By default,
1657 the server file is in @file{~/.emacs.d/server/}. On Microsoft
1658 Windows, if @command{emacsclient} does not find the server file there,
1659 it looks in the @file{.emacs.d/server/} subdirectory of the directory
1660 pointed to by the @env{APPDATA} environment variable. You can tell
1661 @command{emacsclient} to use a specific server file with the @samp{-f}
1662 or @samp{--server-file} option, or by setting the
1663 @env{EMACS_SERVER_FILE} environment variable.
1665 Even if local sockets are available, you can tell Emacs to use TCP by
1666 setting the variable @code{server-use-tcp} to @code{t}. One advantage
1667 of TCP is that the server can accept connections from remote machines.
1668 For this to work, you must (i) set the variable @code{server-host} to
1669 the hostname or IP address of the machine on which the Emacs server
1670 runs, and (ii) provide @command{emacsclient} with the server file.
1671 (One convenient way to do the latter is to put the server file on a
1672 networked file system such as NFS.)
1676 Let @command{emacsclient} exit immediately, instead of waiting until
1677 all server buffers are finished. You can take as long as you like to
1678 edit the server buffers within Emacs, and they are @emph{not} killed
1679 when you type @kbd{C-x #} in them.
1683 Do not let @command{emacsclient} display messages about waiting for
1684 Emacs or connecting to remote server sockets.
1686 @item -s @var{server-name}
1687 @itemx --socket-name=@var{server-name}
1688 Connect to the Emacs server named @var{server-name}. The server name
1689 is given by the variable @code{server-name} on the Emacs server. If
1690 this option is omitted, @command{emacsclient} connects to the first
1691 server it finds. (This option is not supported on MS-Windows.)
1696 Create a new Emacs frame on the current text-only terminal, instead of
1697 using an existing Emacs frame. Emacs 23 can open a text-only terminal
1698 even if it was started in another text-only terminal, or on a
1699 graphical display. If you omit a filename argument while supplying
1700 this option, the new frame displays the @samp{*scratch*} buffer.
1704 If you type @kbd{C-x C-c} (@code{save-buffers-kill-terminal}) in an
1705 Emacs frame created with @command{emacsclient}, via the @samp{-c} or
1706 @samp{-t} options, Emacs deletes the frame instead of killing the
1707 Emacs process itself. On a text-only terminal frame created with the
1708 @samp{-t} option, this returns control to the terminal. Emacs also
1709 marks all the server buffers for the client as finished, as though you
1710 had typed @kbd{C-x #} in all of them.
1712 When Emacs is started as a daemon, all frames are considered client
1713 frames, so @kbd{C-x C-c} will never kill Emacs. To kill the Emacs
1714 process, type @kbd{M-x kill-emacs}.
1716 @node Printing, Sorting, Emacs Server, Top
1717 @section Printing Hard Copies
1721 Emacs provides commands for printing hard copies of either an entire
1722 buffer or just part of one, with or without page headers. You can
1723 invoke the printing commands directly, as detailed in the following
1724 section, or using the @samp{File} menu on the menu bar.
1726 @findex htmlfontify-buffer
1727 Aside from the commands described in this section, you can also
1728 ``print'' an Emacs buffer to HTML with @kbd{M-x htmlfontify-buffer}.
1729 This command converts the current buffer to a HTML file, replacing
1730 Emacs faces with CSS-based markup. In addition, see the hardcopy
1731 commands of Dired (@pxref{Misc File Ops}) and the diary
1732 (@pxref{Displaying the Diary}).
1735 @item M-x print-buffer
1736 Print hardcopy of current buffer with page headings containing the file
1737 name and page number.
1738 @item M-x lpr-buffer
1739 Print hardcopy of current buffer without page headings.
1740 @item M-x print-region
1741 Like @code{print-buffer} but print only the current region.
1742 @item M-x lpr-region
1743 Like @code{lpr-buffer} but print only the current region.
1746 @findex print-buffer
1747 @findex print-region
1750 @vindex lpr-switches
1751 The hardcopy commands (aside from the PostScript commands) pass extra
1752 switches to the @code{lpr} program based on the value of the variable
1753 @code{lpr-switches}. Its value should be a list of strings, each string
1754 an option starting with @samp{-}. For example, to specify a line width
1755 of 80 columns for all the printing you do in Emacs, set
1756 @code{lpr-switches} like this:
1759 (setq lpr-switches '("-w80"))
1762 @vindex printer-name
1763 You can specify the printer to use by setting the variable
1764 @code{printer-name}.
1766 @vindex lpr-headers-switches
1767 @vindex lpr-commands
1768 @vindex lpr-add-switches
1769 The variable @code{lpr-command} specifies the name of the printer
1770 program to run; the default value depends on your operating system type.
1771 On most systems, the default is @code{"lpr"}. The variable
1772 @code{lpr-headers-switches} similarly specifies the extra switches to
1773 use to make page headers. The variable @code{lpr-add-switches} controls
1774 whether to supply @samp{-T} and @samp{-J} options (suitable for
1775 @code{lpr}) to the printer program: @code{nil} means don't add them.
1776 @code{lpr-add-switches} should be @code{nil} if your printer program is
1777 not compatible with @code{lpr}.
1780 * PostScript:: Printing buffers or regions as PostScript.
1781 * PostScript Variables:: Customizing the PostScript printing commands.
1782 * Printing Package:: An optional advanced printing interface.
1785 @node PostScript, PostScript Variables,, Printing
1786 @section PostScript Hardcopy
1788 These commands convert buffer contents to PostScript,
1789 either printing it or leaving it in another Emacs buffer.
1792 @item M-x ps-print-buffer
1793 Print hardcopy of the current buffer in PostScript form.
1794 @item M-x ps-print-region
1795 Print hardcopy of the current region in PostScript form.
1796 @item M-x ps-print-buffer-with-faces
1797 Print hardcopy of the current buffer in PostScript form, showing the
1798 faces used in the text by means of PostScript features.
1799 @item M-x ps-print-region-with-faces
1800 Print hardcopy of the current region in PostScript form, showing the
1801 faces used in the text.
1802 @item M-x ps-spool-buffer
1803 Generate and spool a PostScript image for the current buffer text.
1804 @item M-x ps-spool-region
1805 Generate and spool a PostScript image for the current region.
1806 @item M-x ps-spool-buffer-with-faces
1807 Generate and spool a PostScript image for the current buffer, showing the faces used.
1808 @item M-x ps-spool-region-with-faces
1809 Generate and spool a PostScript image for the current region, showing the faces used.
1810 @item M-x ps-despool
1811 Send the spooled PostScript to the printer.
1813 Generate/print PostScript for the current buffer as if handwritten.
1816 @findex ps-print-region
1817 @findex ps-print-buffer
1818 @findex ps-print-region-with-faces
1819 @findex ps-print-buffer-with-faces
1820 The PostScript commands, @code{ps-print-buffer} and
1821 @code{ps-print-region}, print buffer contents in PostScript form. One
1822 command prints the entire buffer; the other, just the region. The
1823 corresponding @samp{-with-faces} commands,
1824 @code{ps-print-buffer-with-faces} and @code{ps-print-region-with-faces},
1825 use PostScript features to show the faces (fonts and colors) in the text
1826 properties of the text being printed. The @samp{-with-faces} commands only
1827 work if they are used in a window system, so it has a way to determine color
1830 Interactively, when you use a prefix argument (@kbd{C-u}), the command
1831 prompts the user for a file name, and saves the PostScript image in that file
1832 instead of sending it to the printer.
1834 Noninteractively, the argument @var{filename} is treated as follows: if it is
1835 @code{nil}, send the image to the printer. If @var{filename} is a string, save
1836 the PostScript image in a file with that name.
1838 If you are using a color display, you can print a buffer of program
1839 code with color highlighting by turning on Font-Lock mode in that
1840 buffer, and using @code{ps-print-buffer-with-faces}.
1842 @findex ps-spool-region
1843 @findex ps-spool-buffer
1844 @findex ps-spool-region-with-faces
1845 @findex ps-spool-buffer-with-faces
1846 The commands whose names have @samp{spool} instead of @samp{print},
1847 generate the PostScript output in an Emacs buffer instead of sending
1850 Use the command @code{ps-despool} to send the spooled images to the printer.
1853 This command sends the PostScript generated by @samp{-spool-} commands (see
1854 commands above) to the printer.
1856 Interactively, when you use a prefix argument (@kbd{C-u}), the command
1857 prompts the user for a file name, and saves the spooled PostScript image in
1858 that file instead of sending it to the printer.
1860 Noninteractively, the argument @var{filename} is treated as follows: if it is
1861 @code{nil}, send the image to the printer. If @var{filename} is a string, save
1862 the PostScript image in a file with that name.
1866 @kbd{M-x handwrite} is more frivolous. It generates a PostScript
1867 rendition of the current buffer as a cursive handwritten document. It
1868 can be customized in group @code{handwrite}. This function only
1869 supports ISO 8859-1 characters.
1872 The following section describes variables for customizing these commands.
1875 @node PostScript Variables, Printing Package, PostScript, Printing
1876 @section Variables for PostScript Hardcopy
1878 @vindex ps-lpr-command
1879 @vindex ps-lpr-switches
1880 @vindex ps-printer-name
1881 All the PostScript hardcopy commands use the variables
1882 @code{ps-lpr-command} and @code{ps-lpr-switches} to specify how to print
1883 the output. @code{ps-lpr-command} specifies the command name to run,
1884 @code{ps-lpr-switches} specifies command line options to use, and
1885 @code{ps-printer-name} specifies the printer. If you don't set the
1886 first two variables yourself, they take their initial values from
1887 @code{lpr-command} and @code{lpr-switches}. If @code{ps-printer-name}
1888 is @code{nil}, @code{printer-name} is used.
1890 @vindex ps-print-header
1891 The variable @code{ps-print-header} controls whether these commands
1892 add header lines to each page---set it to @code{nil} to turn headers
1895 @cindex color emulation on black-and-white printers
1896 @vindex ps-print-color-p
1897 If your printer doesn't support colors, you should turn off color
1898 processing by setting @code{ps-print-color-p} to @code{nil}. By
1899 default, if the display supports colors, Emacs produces hardcopy output
1900 with color information; on black-and-white printers, colors are emulated
1901 with shades of gray. This might produce illegible output, even if your
1902 screen colors only use shades of gray.
1904 Alternatively, you can set @code{ps-print-color-p} to @code{black-white} to
1905 print colors on black/white printers.
1907 @vindex ps-use-face-background
1908 By default, PostScript printing ignores the background colors of the
1909 faces, unless the variable @code{ps-use-face-background} is
1910 non-@code{nil}. This is to avoid unwanted interference with the zebra
1911 stripes and background image/text.
1913 @vindex ps-paper-type
1914 @vindex ps-page-dimensions-database
1915 The variable @code{ps-paper-type} specifies which size of paper to
1916 format for; legitimate values include @code{a4}, @code{a3},
1917 @code{a4small}, @code{b4}, @code{b5}, @code{executive}, @code{ledger},
1918 @code{legal}, @code{letter}, @code{letter-small}, @code{statement},
1919 @code{tabloid}. The default is @code{letter}. You can define
1920 additional paper sizes by changing the variable
1921 @code{ps-page-dimensions-database}.
1923 @vindex ps-landscape-mode
1924 The variable @code{ps-landscape-mode} specifies the orientation of
1925 printing on the page. The default is @code{nil}, which stands for
1926 ``portrait'' mode. Any non-@code{nil} value specifies ``landscape''
1929 @vindex ps-number-of-columns
1930 The variable @code{ps-number-of-columns} specifies the number of
1931 columns; it takes effect in both landscape and portrait mode. The
1934 @vindex ps-font-family
1935 @vindex ps-font-size
1936 @vindex ps-font-info-database
1937 The variable @code{ps-font-family} specifies which font family to use
1938 for printing ordinary text. Legitimate values include @code{Courier},
1939 @code{Helvetica}, @code{NewCenturySchlbk}, @code{Palatino} and
1940 @code{Times}. The variable @code{ps-font-size} specifies the size of
1941 the font for ordinary text. It defaults to 8.5 points.
1943 @vindex ps-multibyte-buffer
1944 @cindex Intlfonts for PostScript printing
1945 @cindex fonts for PostScript printing
1946 Emacs supports more scripts and characters than a typical PostScript
1947 printer. Thus, some of the characters in your buffer might not be
1948 printable using the fonts built into your printer. You can augment
1949 the fonts supplied with the printer with those from the GNU Intlfonts
1950 package, or you can instruct Emacs to use Intlfonts exclusively. The
1951 variable @code{ps-multibyte-buffer} controls this: the default value,
1952 @code{nil}, is appropriate for printing @acronym{ASCII} and Latin-1
1953 characters; a value of @code{non-latin-printer} is for printers which
1954 have the fonts for @acronym{ASCII}, Latin-1, Japanese, and Korean
1955 characters built into them. A value of @code{bdf-font} arranges for
1956 the BDF fonts from the Intlfonts package to be used for @emph{all}
1957 characters. Finally, a value of @code{bdf-font-except-latin}
1958 instructs the printer to use built-in fonts for @acronym{ASCII} and Latin-1
1959 characters, and Intlfonts BDF fonts for the rest.
1961 @vindex bdf-directory-list
1962 To be able to use the BDF fonts, Emacs needs to know where to find
1963 them. The variable @code{bdf-directory-list} holds the list of
1964 directories where Emacs should look for the fonts; the default value
1965 includes a single directory @file{/usr/local/share/emacs/fonts/bdf}.
1967 Many other customization variables for these commands are defined and
1968 described in the Lisp files @file{ps-print.el} and @file{ps-mule.el}.
1970 @node Printing Package,, PostScript Variables, Printing
1971 @section Printing Package
1972 @cindex Printing package
1974 The basic Emacs facilities for printing hardcopy can be extended
1975 using the Printing package. This provides an easy-to-use interface
1976 for choosing what to print, previewing PostScript files before
1977 printing, and setting various printing options such as print headers,
1978 landscape or portrait modes, duplex modes, and so forth. On GNU/Linux
1979 or Unix systems, the Printing package relies on the @file{gs} and
1980 @file{gv} utilities, which are distributed as part of the GhostScript
1981 program. On MS-Windows, the @file{gstools} port of Ghostscript can be
1984 @findex pr-interface
1985 To use the Printing package, add @code{(require 'printing)} to your
1986 init file (@pxref{Init File}), followed by @code{(pr-update-menus)}.
1987 This function replaces the usual printing commands in the menu bar
1988 with a @samp{Printing} submenu that contains various printing options.
1989 You can also type @kbd{M-x pr-interface RET}; this creates a
1990 @samp{*Printing Interface*} buffer, similar to a customization buffer,
1991 where you can set the printing options. After selecting what and how
1992 to print, you start the print job using the @samp{Print} button (click
1993 @kbd{mouse-2} on it, or move point over it and type @kbd{RET}). For
1994 further information on the various options, use the @samp{Interface
1997 @node Sorting, Narrowing, Printing, Top
1998 @section Sorting Text
2001 Emacs provides several commands for sorting text in the buffer. All
2002 operate on the contents of the region.
2003 They divide the text of the region into many @dfn{sort records},
2004 identify a @dfn{sort key} for each record, and then reorder the records
2005 into the order determined by the sort keys. The records are ordered so
2006 that their keys are in alphabetical order, or, for numeric sorting, in
2007 numeric order. In alphabetic sorting, all upper-case letters `A' through
2008 `Z' come before lower-case `a', in accord with the @acronym{ASCII} character
2011 The various sort commands differ in how they divide the text into sort
2012 records and in which part of each record is used as the sort key. Most of
2013 the commands make each line a separate sort record, but some commands use
2014 paragraphs or pages as sort records. Most of the sort commands use each
2015 entire sort record as its own sort key, but some use only a portion of the
2016 record as the sort key.
2019 @findex sort-paragraphs
2022 @findex sort-numeric-fields
2023 @vindex sort-numeric-base
2025 @item M-x sort-lines
2026 Divide the region into lines, and sort by comparing the entire
2027 text of a line. A numeric argument means sort into descending order.
2029 @item M-x sort-paragraphs
2030 Divide the region into paragraphs, and sort by comparing the entire
2031 text of a paragraph (except for leading blank lines). A numeric
2032 argument means sort into descending order.
2034 @item M-x sort-pages
2035 Divide the region into pages, and sort by comparing the entire
2036 text of a page (except for leading blank lines). A numeric
2037 argument means sort into descending order.
2039 @item M-x sort-fields
2040 Divide the region into lines, and sort by comparing the contents of
2041 one field in each line. Fields are defined as separated by
2042 whitespace, so the first run of consecutive non-whitespace characters
2043 in a line constitutes field 1, the second such run constitutes field
2046 Specify which field to sort by with a numeric argument: 1 to sort by
2047 field 1, etc. A negative argument means count fields from the right
2048 instead of from the left; thus, minus 1 means sort by the last field.
2049 If several lines have identical contents in the field being sorted, they
2050 keep the same relative order that they had in the original buffer.
2052 @item M-x sort-numeric-fields
2053 Like @kbd{M-x sort-fields} except the specified field is converted
2054 to an integer for each line, and the numbers are compared. @samp{10}
2055 comes before @samp{2} when considered as text, but after it when
2056 considered as a number. By default, numbers are interpreted according
2057 to @code{sort-numeric-base}, but numbers beginning with @samp{0x} or
2058 @samp{0} are interpreted as hexadecimal and octal, respectively.
2060 @item M-x sort-columns
2061 Like @kbd{M-x sort-fields} except that the text within each line
2062 used for comparison comes from a fixed range of columns. See below
2065 @item M-x reverse-region
2066 Reverse the order of the lines in the region. This is useful for
2067 sorting into descending order by fields or columns, since those sort
2068 commands do not have a feature for doing that.
2071 For example, if the buffer contains this:
2074 On systems where clash detection (locking of files being edited) is
2075 implemented, Emacs also checks the first time you modify a buffer
2076 whether the file has changed on disk since it was last visited or
2077 saved. If it has, you are asked to confirm that you want to change
2082 applying @kbd{M-x sort-lines} to the entire buffer produces this:
2085 On systems where clash detection (locking of files being edited) is
2086 implemented, Emacs also checks the first time you modify a buffer
2087 saved. If it has, you are asked to confirm that you want to change
2089 whether the file has changed on disk since it was last visited or
2093 where the upper-case @samp{O} sorts before all lower-case letters. If
2094 you use @kbd{C-u 2 M-x sort-fields} instead, you get this:
2097 implemented, Emacs also checks the first time you modify a buffer
2098 saved. If it has, you are asked to confirm that you want to change
2100 On systems where clash detection (locking of files being edited) is
2101 whether the file has changed on disk since it was last visited or
2105 where the sort keys were @samp{Emacs}, @samp{If}, @samp{buffer},
2106 @samp{systems} and @samp{the}.
2108 @findex sort-columns
2109 @kbd{M-x sort-columns} requires more explanation. You specify the
2110 columns by putting point at one of the columns and the mark at the other
2111 column. Because this means you cannot put point or the mark at the
2112 beginning of the first line of the text you want to sort, this command
2113 uses an unusual definition of ``region'': all of the line point is in is
2114 considered part of the region, and so is all of the line the mark is in,
2115 as well as all the lines in between.
2117 For example, to sort a table by information found in columns 10 to 15,
2118 you could put the mark on column 10 in the first line of the table, and
2119 point on column 15 in the last line of the table, and then run
2120 @code{sort-columns}. Equivalently, you could run it with the mark on
2121 column 15 in the first line and point on column 10 in the last line.
2123 This can be thought of as sorting the rectangle specified by point and
2124 the mark, except that the text on each line to the left or right of the
2125 rectangle moves along with the text inside the rectangle.
2128 @vindex sort-fold-case
2129 Many of the sort commands ignore case differences when comparing, if
2130 @code{sort-fold-case} is non-@code{nil}.
2132 @node Narrowing, Two-Column, Sorting, Top
2137 @cindex accessible portion
2139 @dfn{Narrowing} means focusing in on some portion of the buffer,
2140 making the rest temporarily inaccessible. The portion which you can
2141 still get to is called the @dfn{accessible portion}. Canceling the
2142 narrowing, which makes the entire buffer once again accessible, is
2143 called @dfn{widening}. The bounds of narrowing in effect in a buffer
2144 are called the buffer's @dfn{restriction}.
2146 Narrowing can make it easier to concentrate on a single subroutine or
2147 paragraph by eliminating clutter. It can also be used to limit the
2148 range of operation of a replace command or repeating keyboard macro.
2152 Narrow down to between point and mark (@code{narrow-to-region}).
2154 Widen to make the entire buffer accessible again (@code{widen}).
2156 Narrow down to the current page (@code{narrow-to-page}).
2158 Narrow down to the current defun (@code{narrow-to-defun}).
2161 When you have narrowed down to a part of the buffer, that part appears
2162 to be all there is. You can't see the rest, you can't move into it
2163 (motion commands won't go outside the accessible part), you can't change
2164 it in any way. However, it is not gone, and if you save the file all
2165 the inaccessible text will be saved. The word @samp{Narrow} appears in
2166 the mode line whenever narrowing is in effect.
2169 @findex narrow-to-region
2170 The primary narrowing command is @kbd{C-x n n} (@code{narrow-to-region}).
2171 It sets the current buffer's restrictions so that the text in the current
2172 region remains accessible, but all text before the region or after the
2173 region is inaccessible. Point and mark do not change.
2176 @findex narrow-to-page
2178 @findex narrow-to-defun
2179 Alternatively, use @kbd{C-x n p} (@code{narrow-to-page}) to narrow
2180 down to the current page. @xref{Pages}, for the definition of a page.
2181 @kbd{C-x n d} (@code{narrow-to-defun}) narrows down to the defun
2182 containing point (@pxref{Defuns}).
2186 The way to cancel narrowing is to widen with @kbd{C-x n w}
2187 (@code{widen}). This makes all text in the buffer accessible again.
2189 You can get information on what part of the buffer you are narrowed down
2190 to using the @kbd{C-x =} command. @xref{Position Info}.
2192 Because narrowing can easily confuse users who do not understand it,
2193 @code{narrow-to-region} is normally a disabled command. Attempting to use
2194 this command asks for confirmation and gives you the option of enabling it;
2195 if you enable the command, confirmation will no longer be required for
2196 it. @xref{Disabling}.
2198 @node Two-Column, Editing Binary Files, Narrowing, Top
2199 @section Two-Column Editing
2200 @cindex two-column editing
2201 @cindex splitting columns
2202 @cindex columns, splitting
2204 Two-column mode lets you conveniently edit two side-by-side columns of
2205 text. It uses two side-by-side windows, each showing its own
2208 There are three ways to enter two-column mode:
2211 @item @kbd{@key{F2} 2} or @kbd{C-x 6 2}
2214 @findex 2C-two-columns
2215 Enter two-column mode with the current buffer on the left, and on the
2216 right, a buffer whose name is based on the current buffer's name
2217 (@code{2C-two-columns}). If the right-hand buffer doesn't already
2218 exist, it starts out empty; the current buffer's contents are not
2221 This command is appropriate when the current buffer is empty or contains
2222 just one column and you want to add another column.
2224 @item @kbd{@key{F2} s} or @kbd{C-x 6 s}
2228 Split the current buffer, which contains two-column text, into two
2229 buffers, and display them side by side (@code{2C-split}). The current
2230 buffer becomes the left-hand buffer, but the text in the right-hand
2231 column is moved into the right-hand buffer. The current column
2232 specifies the split point. Splitting starts with the current line and
2233 continues to the end of the buffer.
2235 This command is appropriate when you have a buffer that already contains
2236 two-column text, and you wish to separate the columns temporarily.
2238 @item @kbd{@key{F2} b @var{buffer} @key{RET}}
2239 @itemx @kbd{C-x 6 b @var{buffer} @key{RET}}
2242 @findex 2C-associate-buffer
2243 Enter two-column mode using the current buffer as the left-hand buffer,
2244 and using buffer @var{buffer} as the right-hand buffer
2245 (@code{2C-associate-buffer}).
2248 @kbd{@key{F2} s} or @kbd{C-x 6 s} looks for a column separator, which
2249 is a string that appears on each line between the two columns. You can
2250 specify the width of the separator with a numeric argument to
2251 @kbd{@key{F2} s}; that many characters, before point, constitute the
2252 separator string. By default, the width is 1, so the column separator
2253 is the character before point.
2255 When a line has the separator at the proper place, @kbd{@key{F2} s}
2256 puts the text after the separator into the right-hand buffer, and
2257 deletes the separator. Lines that don't have the column separator at
2258 the proper place remain unsplit; they stay in the left-hand buffer, and
2259 the right-hand buffer gets an empty line to correspond. (This is the
2260 way to write a line that ``spans both columns while in two-column
2261 mode'': write it in the left-hand buffer, and put an empty line in the
2267 The command @kbd{C-x 6 @key{RET}} or @kbd{@key{F2} @key{RET}}
2268 (@code{2C-newline}) inserts a newline in each of the two buffers at
2269 corresponding positions. This is the easiest way to add a new line to
2270 the two-column text while editing it in split buffers.
2275 When you have edited both buffers as you wish, merge them with
2276 @kbd{@key{F2} 1} or @kbd{C-x 6 1} (@code{2C-merge}). This copies the
2277 text from the right-hand buffer as a second column in the other buffer.
2278 To go back to two-column editing, use @kbd{@key{F2} s}.
2282 @findex 2C-dissociate
2283 Use @kbd{@key{F2} d} or @kbd{C-x 6 d} to dissociate the two buffers,
2284 leaving each as it stands (@code{2C-dissociate}). If the other buffer,
2285 the one not current when you type @kbd{@key{F2} d}, is empty,
2286 @kbd{@key{F2} d} kills it.
2288 @node Editing Binary Files, Saving Emacs Sessions, Two-Column, Top
2289 @section Editing Binary Files
2293 @cindex editing binary files
2295 There is a special major mode for editing binary files: Hexl mode. To
2296 use it, use @kbd{M-x hexl-find-file} instead of @kbd{C-x C-f} to visit
2297 the file. This command converts the file's contents to hexadecimal and
2298 lets you edit the translation. When you save the file, it is converted
2299 automatically back to binary.
2301 You can also use @kbd{M-x hexl-mode} to translate an existing buffer
2302 into hex. This is useful if you visit a file normally and then discover
2303 it is a binary file.
2305 Ordinary text characters overwrite in Hexl mode. This is to reduce
2306 the risk of accidentally spoiling the alignment of data in the file.
2307 There are special commands for insertion. Here is a list of the
2308 commands of Hexl mode:
2310 @c I don't think individual index entries for these commands are useful--RMS.
2313 Insert a byte with a code typed in decimal.
2316 Insert a byte with a code typed in octal.
2319 Insert a byte with a code typed in hex.
2322 Move to the beginning of a 1k-byte ``page.''
2325 Move to the end of a 1k-byte ``page.''
2328 Move to an address specified in hex.
2331 Move to an address specified in decimal.
2334 Leave Hexl mode, going back to the major mode this buffer had before you
2335 invoked @code{hexl-mode}.
2339 Other Hexl commands let you insert strings (sequences) of binary
2340 bytes, move by @code{short}s or @code{int}s, etc.; type @kbd{C-h a
2341 hexl-@key{RET}} for details.
2344 @node Saving Emacs Sessions, Recursive Edit, Editing Binary Files, Top
2345 @section Saving Emacs Sessions
2346 @cindex saving sessions
2347 @cindex restore session
2348 @cindex remember editing session
2349 @cindex reload files
2352 Use the desktop library to save the state of Emacs from one session
2353 to another. Once you save the Emacs @dfn{desktop}---the buffers,
2354 their file names, major modes, buffer positions, and so on---then
2355 subsequent Emacs sessions reload the saved desktop.
2357 @findex desktop-save
2358 @vindex desktop-save-mode
2359 You can save the desktop manually with the command @kbd{M-x
2360 desktop-save}. You can also enable automatic saving of the desktop
2361 when you exit Emacs, and automatic restoration of the last saved
2362 desktop when Emacs starts: use the Customization buffer (@pxref{Easy
2363 Customization}) to set @code{desktop-save-mode} to @code{t} for future
2364 sessions, or add this line in your init file (@pxref{Init File}):
2367 (desktop-save-mode 1)
2370 @findex desktop-change-dir
2371 @findex desktop-revert
2372 @vindex desktop-path
2373 If you turn on @code{desktop-save-mode} in your init file, then when
2374 Emacs starts, it looks for a saved desktop in the current directory.
2375 (More precisely, it looks in the directories specified by
2376 @var{desktop-path}, and uses the first desktop it finds.)
2377 Thus, you can have separate saved desktops in different directories,
2378 and the starting directory determines which one Emacs reloads. You
2379 can save the current desktop and reload one saved in another directory
2380 by typing @kbd{M-x desktop-change-dir}. Typing @kbd{M-x
2381 desktop-revert} reverts to the desktop previously reloaded.
2383 Specify the option @samp{--no-desktop} on the command line when you
2384 don't want it to reload any saved desktop. This turns off
2385 @code{desktop-save-mode} for the current session. Starting Emacs with
2386 the @samp{--no-init-file} option also disables desktop reloading,
2387 since it bypasses the init file, where @code{desktop-save-mode} is
2390 @vindex desktop-restore-eager
2391 By default, all the buffers in the desktop are restored at one go.
2392 However, this may be slow if there are a lot of buffers in the
2393 desktop. You can specify the maximum number of buffers to restore
2394 immediately with the variable @code{desktop-restore-eager}; the
2395 remaining buffers are restored ``lazily,'' when Emacs is idle.
2397 @findex desktop-clear
2398 @vindex desktop-globals-to-clear
2399 @vindex desktop-clear-preserve-buffers-regexp
2400 Type @kbd{M-x desktop-clear} to empty the Emacs desktop. This kills
2401 all buffers except for internal ones, and clears the global variables
2402 listed in @code{desktop-globals-to-clear}. If you want this to
2403 preserve certain buffers, customize the variable
2404 @code{desktop-clear-preserve-buffers-regexp}, whose value is a regular
2405 expression matching the names of buffers not to kill.
2407 If you want to save minibuffer history from one session to
2408 another, use the @code{savehist} library.
2410 @node Recursive Edit, Emulation, Saving Emacs Sessions, Top
2411 @section Recursive Editing Levels
2412 @cindex recursive editing level
2413 @cindex editing level, recursive
2415 A @dfn{recursive edit} is a situation in which you are using Emacs
2416 commands to perform arbitrary editing while in the middle of another
2417 Emacs command. For example, when you type @kbd{C-r} inside of a
2418 @code{query-replace}, you enter a recursive edit in which you can change
2419 the current buffer. On exiting from the recursive edit, you go back to
2420 the @code{query-replace}.
2423 @findex exit-recursive-edit
2424 @cindex exiting recursive edit
2425 @dfn{Exiting} the recursive edit means returning to the unfinished
2426 command, which continues execution. The command to exit is @kbd{C-M-c}
2427 (@code{exit-recursive-edit}).
2429 You can also @dfn{abort} the recursive edit. This is like exiting,
2430 but also quits the unfinished command immediately. Use the command
2431 @kbd{C-]} (@code{abort-recursive-edit}) to do this. @xref{Quitting}.
2433 The mode line shows you when you are in a recursive edit by displaying
2434 square brackets around the parentheses that always surround the major and
2435 minor mode names. Every window's mode line shows this in the same way,
2436 since being in a recursive edit is true of Emacs as a whole rather than
2437 any particular window or buffer.
2439 It is possible to be in recursive edits within recursive edits. For
2440 example, after typing @kbd{C-r} in a @code{query-replace}, you may type a
2441 command that enters the debugger. This begins a recursive editing level
2442 for the debugger, within the recursive editing level for @kbd{C-r}.
2443 Mode lines display a pair of square brackets for each recursive editing
2444 level currently in progress.
2446 Exiting the inner recursive edit (such as with the debugger @kbd{c}
2447 command) resumes the command running in the next level up. When that
2448 command finishes, you can then use @kbd{C-M-c} to exit another recursive
2449 editing level, and so on. Exiting applies to the innermost level only.
2450 Aborting also gets out of only one level of recursive edit; it returns
2451 immediately to the command level of the previous recursive edit. If you
2452 wish, you can then abort the next recursive editing level.
2454 Alternatively, the command @kbd{M-x top-level} aborts all levels of
2455 recursive edits, returning immediately to the top-level command
2456 reader. It also exits the minibuffer, if it is active.
2458 The text being edited inside the recursive edit need not be the same text
2459 that you were editing at top level. It depends on what the recursive edit
2460 is for. If the command that invokes the recursive edit selects a different
2461 buffer first, that is the buffer you will edit recursively. In any case,
2462 you can switch buffers within the recursive edit in the normal manner (as
2463 long as the buffer-switching keys have not been rebound). You could
2464 probably do all the rest of your editing inside the recursive edit,
2465 visiting files and all. But this could have surprising effects (such as
2466 stack overflow) from time to time. So remember to exit or abort the
2467 recursive edit when you no longer need it.
2469 In general, we try to minimize the use of recursive editing levels in
2470 GNU Emacs. This is because they constrain you to ``go back'' in a
2471 particular order---from the innermost level toward the top level. When
2472 possible, we present different activities in separate buffers so that
2473 you can switch between them as you please. Some commands switch to a
2474 new major mode which provides a command to switch back. These
2475 approaches give you more flexibility to go back to unfinished tasks in
2476 the order you choose.
2478 @node Emulation, Hyperlinking, Recursive Edit, Top
2480 @cindex emulating other editors
2481 @cindex other editors
2484 @cindex PC key bindings
2485 @cindex scrolling all windows
2486 @cindex PC selection
2487 @cindex Motif key bindings
2488 @cindex Macintosh key bindings
2491 GNU Emacs can be programmed to emulate (more or less) most other
2492 editors. Standard facilities can emulate these:
2495 @item CRiSP/Brief (PC editor)
2497 @vindex crisp-override-meta-x
2498 @findex scroll-all-mode
2500 @cindex Brief emulation
2501 @cindex emulation of Brief
2503 You can turn on key bindings to emulate the CRiSP/Brief editor with
2504 @kbd{M-x crisp-mode}. Note that this rebinds @kbd{M-x} to exit Emacs
2505 unless you set the variable @code{crisp-override-meta-x}. You can
2506 also use the command @kbd{M-x scroll-all-mode} or set the variable
2507 @code{crisp-load-scroll-all} to emulate CRiSP's scroll-all feature
2508 (scrolling all windows together).
2510 @item EDT (DEC VMS editor)
2511 @findex edt-emulation-on
2512 @findex edt-emulation-off
2513 Turn on EDT emulation @kbd{M-x edt-emulation-on}; use @kbd{M-x
2514 edt-emulation-off} to restore normal Emacs command bindings.
2516 Most of the EDT emulation commands are keypad keys, and most standard
2517 Emacs key bindings are still available. The EDT emulation rebindings
2518 are done in the global keymap, so there is no problem switching
2519 buffers or major modes while in EDT emulation.
2521 @item TPU (DEC VMS editor)
2524 @kbd{M-x tpu-edt-on} turns on emulation of the TPU editor emulating EDT.
2526 @item vi (Berkeley editor)
2528 Viper is the newest emulator for vi. It implements several levels of
2529 emulation; level 1 is closest to vi itself, while level 5 departs
2530 somewhat from strict emulation to take advantage of the capabilities of
2531 Emacs. To invoke Viper, type @kbd{M-x viper-mode}; it will guide you
2532 the rest of the way and ask for the emulation level. @inforef{Top,
2535 @item vi (another emulator)
2537 @kbd{M-x vi-mode} enters a major mode that replaces the previously
2538 established major mode. All of the vi commands that, in real vi, enter
2539 ``input'' mode are programmed instead to return to the previous major
2540 mode. Thus, ordinary Emacs serves as vi's ``input'' mode.
2542 Because vi emulation works through major modes, it does not work
2543 to switch buffers during emulation. Return to normal Emacs first.
2545 If you plan to use vi emulation much, you probably want to bind a key
2546 to the @code{vi-mode} command.
2548 @item vi (alternate emulator)
2550 @kbd{M-x vip-mode} invokes another vi emulator, said to resemble real vi
2551 more thoroughly than @kbd{M-x vi-mode}. ``Input'' mode in this emulator
2552 is changed from ordinary Emacs so you can use @key{ESC} to go back to
2553 emulated vi command mode. To get from emulated vi command mode back to
2554 ordinary Emacs, type @kbd{C-z}.
2556 This emulation does not work through major modes, and it is possible
2557 to switch buffers in various ways within the emulator. It is not
2558 so necessary to assign a key to the command @code{vip-mode} as
2559 it is with @code{vi-mode} because terminating insert mode does
2562 @inforef{Top, VIP, vip}, for full information.
2564 @item WordStar (old wordprocessor)
2565 @findex wordstar-mode
2566 @kbd{M-x wordstar-mode} provides a major mode with WordStar-like
2570 @node Hyperlinking, Dissociated Press, Emulation, Top
2571 @section Hyperlinking and Navigation Features
2573 @cindex hyperlinking
2575 Various modes documented elsewhere have hypertext features so that
2576 you can follow links, usually by clicking @kbd{Mouse-2} on the link or
2577 typing @key{RET} while point is on the link. Clicking @kbd{Mouse-1}
2578 quickly on the link also follows it. (Hold @kbd{Mouse-1} for longer
2579 if you want to set point instead.)
2581 Info mode, Help mode and the Dired-like modes are examples of modes
2582 that have links in the buffer. The Tags facility links between uses
2583 and definitions in source files, see @ref{Tags}. Imenu provides
2584 navigation amongst items indexed in the current buffer, see
2585 @ref{Imenu}. Info-lookup provides mode-specific lookup of definitions
2586 in Info indexes, see @ref{Documentation}. Speedbar maintains a frame
2587 in which links to files, and locations in files are displayed, see
2590 Other non-mode-specific facilities described in this section enable
2591 following links from the current buffer in a context-sensitive
2595 * Browse-URL:: Following URLs.
2596 * Goto Address mode:: Activating URLs.
2597 * FFAP:: Finding files etc. at point.
2601 @subsection Following URLs
2602 @cindex World Wide Web
2605 @findex browse-url-at-point
2606 @findex browse-url-at-mouse
2611 @item M-x browse-url @key{RET} @var{url} @key{RET}
2612 Load a URL into a Web browser.
2615 The Browse-URL package provides facilities for following URLs specifying
2616 links on the World Wide Web. Usually this works by invoking a web
2617 browser, but you can, for instance, arrange to invoke @code{compose-mail}
2618 from @samp{mailto:} URLs.
2620 The general way to use this feature is to type @kbd{M-x browse-url},
2621 which displays a specified URL. If point is located near a plausible
2622 URL, that URL is used as the default. Other commands are available
2623 which you might like to bind to keys, such as
2624 @code{browse-url-at-point} and @code{browse-url-at-mouse}.
2626 @vindex browse-url-browser-function
2627 You can customize Browse-URL's behavior via various options in the
2628 @code{browse-url} Customize group, particularly
2629 @code{browse-url-browser-function}. You can invoke actions dependent
2630 on the type of URL by defining @code{browse-url-browser-function} as
2631 an association list. The package's commentary available via @kbd{C-h
2632 p} under the @samp{hypermedia} keyword provides more information.
2633 Packages with facilities for following URLs should always go through
2634 Browse-URL, so that the customization options for Browse-URL will
2635 affect all browsing in Emacs.
2637 @node Goto Address mode
2638 @subsection Activating URLs
2639 @findex goto-address-mode
2640 @cindex Goto Address mode
2641 @cindex URLs, activating
2644 @item M-x goto-address-mode
2645 Activate URLs and e-mail addresses in the current buffer.
2648 You can make URLs in the current buffer active with @kbd{M-x
2649 goto-address-mode}. This minor mode finds all the URLs in the buffer,
2650 highlights them, and turns them into @dfn{buttons}: if you click on a
2651 URL with @kbd{Mouse-1} or @kbd{Mouse-2} (@pxref{Mouse References}), or
2652 move to the URL and type @kbd{C-c @key{RET}}, that displays the web
2653 page that the URL specifies. For a @samp{mailto} URL, it sends mail
2654 instead, using your selected mail-composition method (@pxref{Mail
2657 It can be useful to add @code{goto-address-mode} to mode hooks and
2658 the hooks used to display an incoming message (e.g.,
2659 @code{rmail-show-message-hook} for Rmail, and @code{mh-show-mode-hook}
2660 for MH-E). This is not needed for Gnus, which has a similar feature
2664 @subsection Finding Files and URLs at Point
2665 @findex find-file-at-point
2667 @findex dired-at-point
2670 @cindex finding file at point
2672 FFAP mode replaces certain key bindings for finding files, including
2673 @kbd{C-x C-f}, with commands that provide more sensitive defaults.
2674 These commands behave like the ordinary ones when given a prefix
2675 argument. Otherwise, they get the default file name or URL from the
2676 text around point. If what is found in the buffer has the form of a
2677 URL rather than a file name, the commands use @code{browse-url} to
2680 This feature is useful for following references in mail or news
2681 buffers, @file{README} files, @file{MANIFEST} files, and so on. The
2682 @samp{ffap} package's commentary available via @kbd{C-h p} under the
2683 @samp{files} keyword and the @code{ffap} Custom group provide details.
2685 @cindex FFAP minor mode
2687 You can turn on FFAP minor mode by calling @code{ffap-bindings} to
2688 make the following key bindings and to install hooks for using
2689 @code{ffap} in Rmail, Gnus and VM article buffers.
2692 @item C-x C-f @var{filename} @key{RET}
2693 @kindex C-x C-f @r{(FFAP)}
2694 Find @var{filename}, guessing a default from text around point
2695 (@code{find-file-at-point}).
2697 @kindex C-x C-r @r{(FFAP)}
2698 @code{ffap-read-only}, analogous to @code{find-file-read-only}.
2700 @kindex C-x C-v @r{(FFAP)}
2701 @code{ffap-alternate-file}, analogous to @code{find-alternate-file}.
2702 @item C-x d @var{directory} @key{RET}
2703 @kindex C-x d @r{(FFAP)}
2704 Start Dired on @var{directory}, defaulting to the directory name at
2705 point (@code{dired-at-point}).
2707 @code{ffap-list-directory}, analogous to @code{list-directory}.
2709 @kindex C-x 4 f @r{(FFAP)}
2710 @code{ffap-other-window}, analogous to @code{find-file-other-window}.
2712 @code{ffap-read-only-other-window}, analogous to
2713 @code{find-file-read-only-other-window}.
2715 @code{ffap-dired-other-window}, analogous to @code{dired-other-window}.
2717 @kindex C-x 5 f @r{(FFAP)}
2718 @code{ffap-other-frame}, analogous to @code{find-file-other-frame}.
2720 @code{ffap-read-only-other-frame}, analogous to
2721 @code{find-file-read-only-other-frame}.
2723 @code{ffap-dired-other-frame}, analogous to @code{dired-other-frame}.
2725 Search buffer for next file name or URL, then find that file or URL.
2727 @kindex S-Mouse-3 @r{(FFAP)}
2728 @code{ffap-at-mouse} finds the file guessed from text around the position
2731 @kindex C-S-Mouse-3 @r{(FFAP)}
2732 Display a menu of files and URLs mentioned in current buffer, then
2733 find the one you select (@code{ffap-menu}).
2736 @node Dissociated Press, Amusements, Hyperlinking, Top
2737 @section Dissociated Press
2739 @findex dissociated-press
2740 @kbd{M-x dissociated-press} is a command for scrambling a file of text
2741 either word by word or character by character. Starting from a buffer of
2742 straight English, it produces extremely amusing output. The input comes
2743 from the current Emacs buffer. Dissociated Press writes its output in a
2744 buffer named @samp{*Dissociation*}, and redisplays that buffer after every
2745 couple of lines (approximately) so you can read the output as it comes out.
2747 Dissociated Press asks every so often whether to continue generating
2748 output. Answer @kbd{n} to stop it. You can also stop at any time by
2749 typing @kbd{C-g}. The dissociation output remains in the
2750 @samp{*Dissociation*} buffer for you to copy elsewhere if you wish.
2752 @cindex presidentagon
2753 Dissociated Press operates by jumping at random from one point in
2754 the buffer to another. In order to produce plausible output rather
2755 than gibberish, it insists on a certain amount of overlap between the
2756 end of one run of consecutive words or characters and the start of the
2757 next. That is, if it has just output `president' and then decides to
2758 jump to a different point in the buffer, it might spot the `ent' in
2759 `pentagon' and continue from there, producing `presidentagon'. Long
2760 sample texts produce the best results.
2762 @cindex againformation
2763 A positive argument to @kbd{M-x dissociated-press} tells it to operate
2764 character by character, and specifies the number of overlap characters. A
2765 negative argument tells it to operate word by word, and specifies the number
2766 of overlap words. In this mode, whole words are treated as the elements to
2767 be permuted, rather than characters. No argument is equivalent to an
2768 argument of two. For your againformation, the output goes only into the
2769 buffer @samp{*Dissociation*}. The buffer you start with is not changed.
2771 @cindex Markov chain
2773 @cindex techniquitous
2774 Dissociated Press produces results fairly like those of a Markov
2775 chain based on a frequency table constructed from the sample text. It
2776 is, however, an independent, ignoriginal invention. Dissociated Press
2777 techniquitously copies several consecutive characters from the sample
2778 text between random jumps, unlike a Markov chain which would jump
2779 randomly after each word or character. This makes for more plausible
2780 sounding results, and runs faster.
2786 @cindex developediment
2788 It is a mustatement that too much use of Dissociated Press can be a
2789 developediment to your real work, sometimes to the point of outragedy.
2790 And keep dissociwords out of your documentation, if you want it to be well
2791 userenced and properbose. Have fun. Your buggestions are welcome.
2793 @node Amusements, Customization, Dissociated Press, Top
2794 @section Other Amusements
2799 @cindex tower of Hanoi
2801 If you are a little bit bored, you can try @kbd{M-x hanoi}. If you are
2802 considerably bored, give it a numeric argument. If you are very, very
2803 bored, try an argument of 9. Sit back and watch.
2806 If you want a little more personal involvement, try @kbd{M-x gomoku},
2807 which plays the game Go Moku with you.
2810 @kbd{M-x bubbles} is a game in which the object is to remove as many
2811 bubbles as you can in the smallest number of moves.
2817 @kbd{M-x blackbox}, @kbd{M-x mpuz} and @kbd{M-x 5x5} are puzzles.
2818 @code{blackbox} challenges you to determine the location of objects
2819 inside a box by tomography. @code{mpuz} displays a multiplication
2820 puzzle with letters standing for digits in a code that you must
2821 guess---to guess a value, type a letter and then the digit you think it
2822 stands for. The aim of @code{5x5} is to fill in all the squares.
2826 @cindex cryptanalysis
2827 @kbd{M-x decipher} helps you to cryptanalyze a buffer which is encrypted
2828 in a simple monoalphabetic substitution cipher.
2831 @kbd{M-x dunnet} runs an adventure-style exploration game, which is
2832 a bigger sort of puzzle.
2835 @cindex landmark game
2836 @kbd{M-x lm} runs a relatively non-participatory game in which a robot
2837 attempts to maneuver towards a tree at the center of the window based on
2838 unique olfactory cues from each of the four directions.
2842 @kbd{M-x life} runs Conway's ``Life'' cellular automaton.
2844 @findex morse-region
2845 @findex unmorse-region
2847 @cindex --/---/.-./.../.
2848 @kbd{M-x morse-region} converts text in a region to Morse code and
2849 @kbd{M-x unmorse-region} converts it back. No cause for remorse.
2853 @kbd{M-x pong} plays a Pong-like game, bouncing the ball off opposing
2858 @kbd{M-x solitaire} plays a game of solitaire in which you jump pegs
2861 @findex animate-birthday-present
2863 The @code{animate} package makes text dance. For an example, try
2864 @kbd{M-x animate-birthday-present}.
2866 @findex studlify-region
2868 @kbd{M-x studlify-region} studlify-cases the region, producing
2872 M-x stUdlIfY-RegioN stUdlIfY-CaSeS thE region.
2879 @kbd{M-x tetris} runs an implementation of the well-known Tetris game.
2880 Likewise, @kbd{M-x snake} provides an implementation of Snake.
2882 When you are frustrated, try the famous Eliza program. Just do
2883 @kbd{M-x doctor}. End each input by typing @key{RET} twice.
2886 When you are feeling strange, type @kbd{M-x yow}.
2889 The command @kbd{M-x zone} plays games with the display when Emacs is