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This is Info file ../../info/xemacs.info, produced by Makeinfo version 1.68 from the input file xemacs.texi. This file documents the XEmacs editor. Copyright (C) 1985, 1986, 1988 Richard M. Stallman. Copyright (C) 1991, 1992, 1993, 1994 Lucid, Inc. Copyright (C) 1993, 1994 Sun Microsystems, Inc. Copyright (C) 1995 Amdahl Corporation. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" may be included in a translation approved by the author instead of in the original English. File: xemacs.info, Node: Exiting, Next: Command Switches, Prev: Entering Emacs, Up: Top Exiting Emacs ============= There are two commands for exiting Emacs because there are two kinds of exiting: "suspending" Emacs and "killing" Emacs. "Suspending" means stopping Emacs temporarily and returning control to its superior (usually the shell), allowing you to resume editing later in the same Emacs job, with the same files, same kill ring, same undo history, and so on. This is the usual way to exit. "Killing" Emacs means destroying the Emacs job. You can run Emacs again later, but you will get a fresh Emacs; there is no way to resume the same editing session after it has been killed. `C-z' Suspend Emacs (`suspend-emacs'). If used under the X window system, shrink the X window containing the Emacs frame to an icon (see below). `C-x C-c' Kill Emacs (`save-buffers-kill-emacs'). If you use XEmacs under the X window system, `C-z' shrinks the X window containing the Emacs frame to an icon. The Emacs process is stopped temporarily, and control is returned to the window manager. If more than one frame is associated with the Emacs process, only the frame from which you used `C-z' is retained. The X windows containing the other Emacs frames are closed. To activate the "suspended" Emacs, use the appropriate window manager mouse gestures. Usually left-clicking on the icon reactivates and reopens the X window containing the Emacs frame, but the window manager you use determines what exactly happens. To actually kill the Emacs process, use `C-x C-c' or the Exit Emacs item on the File menu. On systems that do not permit programs to be suspended, `C-z' runs an inferior shell that communicates directly with the terminal, and Emacs waits until you exit the subshell. On these systems, the only way to return to the shell from which Emacs was started (to log out, for example) is to kill Emacs. `C-d' or `exit' are typical commands to exit a subshell. To kill Emacs, type `C-x C-c' (`save-buffers-kill-emacs'). A two-character key is used for this to make it harder to type. In XEmacs, selecting the Exit Emacs option of the File menu is an alternate way of issuing the command. Unless a numeric argument is used, this command first offers to save any modified buffers. If you do not save all buffers, you are asked for reconfirmation with `yes' before killing Emacs, since any changes not saved will be lost. If any subprocesses are still running, `C-x C-c' asks you to confirm killing them, since killing Emacs kills the subprocesses simultaneously. In most programs running on Unix, certain characters may instantly suspend or kill the program. (In Berkeley Unix these characters are normally `C-z' and `C-c'.) This Unix feature is turned off while you are in Emacs. The meanings of `C-z' and `C-x C-c' as keys in Emacs were inspired by the standard Berkeley Unix meanings of `C-z' and `C-c', but that is their only relationship with Unix. You could customize these keys to do anything (*note Keymaps::.). File: xemacs.info, Node: Command Switches, Next: Basic, Prev: Exiting, Up: Top Command Line Switches and Arguments =================================== XEmacs supports command line arguments you can use to request various actions when invoking Emacs. The commands are for compatibility with other editors and for sophisticated activities. If you are using XEmacs under the X window system, you can also use a number of standard Xt command line arguments. Command line arguments are not usually needed for editing with Emacs; new users can skip this section. Many editors are designed to be started afresh each time you want to edit. You start the editor to edit one file; then exit the editor. The next time you want to edit either another file or the same one, you start the editor again. Under these circumstances, it makes sense to use a command line argument to say which file to edit. The recommended way to use XEmacs is to start it only once, just after you log in, and do all your editing in the same Emacs process. Each time you want to edit a file, you visit it using the existing Emacs. Emacs creates a new buffer for each file, and (unless you kill some of the buffers) Emacs eventually has many files in it ready for editing. Usually you do not kill the Emacs process until you are about to log out. Since you usually read files by typing commands to Emacs, command line arguments for specifying a file when Emacs is started are seldom needed. Emacs accepts command-line arguments that specify files to visit, functions to call, and other activities and operating modes. If you are running XEmacs under the X window system, a number of standard Xt command line arguments are available as well. The following subsections list: * Command line arguments that you can always use * Command line arguments that have to appear at the beginning of the argument list * Command line arguments that are only relevant if you are running XEmacs under X Command Line Arguments for Any Position --------------------------------------- Command line arguments are processed in the order they appear on the command line; however, certain arguments (the ones in the second table) must be at the front of the list if they are used. Here are the arguments allowed: `FILE' Visit FILE using `find-file'. *Note Visiting::. `+LINENUM FILE' Visit FILE using `find-file', then go to line number LINENUM in it. `-load FILE' `-l FILE' Load a file FILE of Lisp code with the function `load'. *Note Lisp Libraries::. `-funcall FUNCTION' `-f FUNCTION' Call Lisp function FUNCTION with no arguments. `-eval FUNCTION' Interpret the next argument as a Lisp expression, and evaluate it. You must be very careful of the shell quoting here. `-insert FILE' `-i FILE' Insert the contents of FILE into the current buffer. This is like what `M-x insert-buffer' does; *Note Misc File Ops::. `-kill' Exit from Emacs without asking for confirmation. `-version' Prints version information. This implies `-batch'. % xemacs -version XEmacs 19.13 of Mon Aug 21 1995 on willow (usg-unix-v) [formerly Lucid Emacs] `-help' Prints a summary of command-line options and then exits. Command Line Arguments (Beginning of Line Only) ----------------------------------------------- The following arguments are recognized only at the beginning of the command line. If more than one of them appears, they must appear in the order in which they appear in this table. `-t FILE' Use FILE instead of the terminal for input and output. This implies the `-nw' option, documented below. `-batch' Run Emacs in "batch mode", which means that the text being edited is not displayed and the standard Unix interrupt characters such as `C-z' and `C-c' continue to have their normal effect. Emacs in batch mode outputs to `stderr' only what would normally be printed in the echo area under program control. Batch mode is used for running programs written in Emacs Lisp from shell scripts, makefiles, and so on. Normally the `-l' switch or `-f' switch will be used as well, to invoke a Lisp program to do the batch processing. `-batch' implies `-q' (do not load an init file). It also causes Emacs to kill itself after all command switches have been processed. In addition, auto-saving is not done except in buffers for which it has been explicitly requested. `-nw' Start up XEmacs in TTY mode (using the TTY XEmacs was started from), rather than trying to connect to an X display. Note that this happens automatically if the `DISPLAY' environment variable is not set. `-debug-init' Enter the debugger if an error in the init file occurs. `-unmapped' Do not map the initial frame. This is useful if you want to start up XEmacs as a server (e.g. for gnuserv screens or external client widgets). `-no-init-file' `-q' Do not load your Emacs init file `~/.emacs'. `-no-site-file' Do not load the site-specific init file `lisp/site-start.el'. `-user USER' `-u USER' Load USER's Emacs init file `~USER/.emacs' instead of your own. Note that the init file can get access to the command line argument values as the elements of a list in the variable `command-line-args'. (The arguments in the second table above will already have been processed and will not be in the list.) The init file can override the normal processing of the other arguments by setting this variable. One way to use command switches is to visit many files automatically: xemacs *.c passes each `.c' file as a separate argument to Emacs, so that Emacs visits each file (*note Visiting::.). Here is an advanced example that assumes you have a Lisp program file called `hack-c-program.el' which, when loaded, performs some useful operation on the current buffer, expected to be a C program. xemacs -batch foo.c -l hack-c-program -f save-buffer -kill > log Here Emacs is told to visit `foo.c', load `hack-c-program.el' (which makes changes in the visited file), save `foo.c' (note that `save-buffer' is the function that `C-x C-s' is bound to), and then exit to the shell from which the command was executed. `-batch' guarantees there will be no problem redirecting output to `log', because Emacs will not assume that it has a display terminal to work with. Command Line Arguments (for XEmacs Under X) ------------------------------------------- If you are running XEmacs under X, a number of options are available to control color, border, and window title and icon name: `-title TITLE' `-wn TITLE' `-T TITLE' Use TITLE as the window title. This sets the `frame-title-format' variable, which controls the title of the X window corresponding to the selected frame. This is the same format as `mode-line-format'. `-iconname TITLE' `-in TITLE' Use TITLE as the icon name. This sets the `frame-icon-title-format' variable, which controls the title of the icon corresponding to the selected frame. `-mc COLOR' Use COLOR as the mouse color. `-cr COLOR' Use COLOR as the text-cursor foreground color. In addition, XEmacs allows you to use a number of standard Xt command line arguments. `-background COLOR' `-bg COLOR' Use COLOR as the background color. `-bordercolor COLOR' `-bd COLOR' Use COLOR as the border color. `-borderwidth WIDTH' `-bw WIDTH' Use WIDTH as the border width. `-display DISPLAY' `-d DISPLAY' When running under the X window system, create the window containing the Emacs frame on the display named DISPLAY. `-foreground COLOR' `-fg COLOR' Use COLOR as the foreground color. `-font NAME' `-fn NAME' Use NAME as the default font. `-geometry SPEC' `-geom SPEC' `-g SPEC' Use the geometry (window size and/or position) specified by SPEC. `-iconic' Start up iconified. `-rv' Bring up Emacs in reverse video. `-name NAME' Use the resource manager resources specified by NAME. The default is to use the name of the program (`argv[0]') as the resource manager name. `-xrm' Read something into the resource database for this invocation of Emacs only. File: xemacs.info, Node: Basic, Next: Undo, Prev: Command Switches, Up: Top Basic Editing Commands ********************** We now give the basics of how to enter text, make corrections, and save the text in a file. If this material is new to you, you might learn it more easily by running the Emacs learn-by-doing tutorial. To do this, type `Control-h t' (`help-with-tutorial'). Inserting Text ============== To insert printing characters into the text you are editing, just type them. This inserts the characters into the buffer at the cursor (that is, at "point"; *note Point::.). The cursor moves forward. Any characters after the cursor move forward too. If the text in the buffer is `FOOBAR', with the cursor before the `B', and you type `XX', the result is `FOOXXBAR', with the cursor still before the `B'. To "delete" text you have just inserted, use <DEL>. <DEL> deletes the character BEFORE the cursor (not the one that the cursor is on top of or under; that is the character AFTER the cursor). The cursor and all characters after it move backwards. Therefore, if you type a printing character and then type <DEL>, they cancel out. To end a line and start typing a new one, type <RET>. This inserts a newline character in the buffer. If point is in the middle of a line, <RET> splits the line. Typing <DEL> when the cursor is at the beginning of a line rubs out the newline before the line, thus joining the line with the preceding line. Emacs automatically splits lines when they become too long, if you turn on a special mode called "Auto Fill" mode. *Note Filling::, for information on using Auto Fill mode. Customization information: <DEL>, in most modes, runs the command `delete-backward-char'; <RET> runs the command `newline', and self-inserting printing characters run the command `self-insert', which inserts whatever character was typed to invoke it. Some major modes rebind <DEL> to other commands. Direct insertion works for printing characters and <SPC>, but other characters act as editing commands and do not insert themselves. If you need to insert a control character or a character whose code is above 200 octal, you must "quote" it by typing the character `control-q' (`quoted-insert') first. There are two ways to use `C-q': * `Control-q' followed by any non-graphic character (even `C-g') inserts that character. * `Control-q' followed by three octal digits inserts the character with the specified character code. A numeric argument to `C-q' specifies how many copies of the quoted character should be inserted (*note Arguments::.). If you prefer to have text characters replace (overwrite) existing text instead of moving it to the right, you can enable Overwrite mode, a minor mode. *Note Minor Modes::. Changing the Location of Point ============================== To do more than insert characters, you have to know how to move point (*note Point::.). Here are a few of the available commands. NOTE: Many of the following commands have two versions, one that uses the function keys (e.g. <LEFT> or <END>) and one that doesn't. The former versions may only be available on X terminals (i.e. not on TTY's), but the latter are available on all terminals. `C-a' `HOME' Move to the beginning of the line (`beginning-of-line'). `C-e' `END' Move to the end of the line (`end-of-line'). `C-f' `RIGHT' Move forward one character (`forward-char'). `C-b' `LEFT' Move backward one character (`backward-char'). `M-f' `C-RIGHT' Move forward one word (`forward-word'). `M-b' `C-LEFT' Move backward one word (`backward-word'). `C-n' `DOWN' Move down one line, vertically (`next-line'). This command attempts to keep the horizontal position unchanged, so if you start in the middle of one line, you end in the middle of the next. When on the last line of text, `C-n' creates a new line and moves onto it. `C-p' `UP' Move up one line, vertically (`previous-line'). `C-v' `PGDN' Move down one page, vertically (`scroll-up'). `M-v' `PGUP' Move up one page, vertically (`scroll-down'). `C-l' Clear the frame and reprint everything (`recenter'). Text moves on the frame to bring point to the center of the window. `M-r' Move point to left margin on the line halfway down the frame or window (`move-to-window-line'). Text does not move on the frame. A numeric argument says how many screen lines down from the top of the window (zero for the top). A negative argument counts from the bottom (-1 for the bottom). `C-t' Transpose two characters, the ones before and after the cursor (`transpose-chars'). `M-<' `C-HOME' Move to the top of the buffer (`beginning-of-buffer'). With numeric argument N, move to N/10 of the way from the top. *Note Arguments::, for more information on numeric arguments. `M->' `C-END' Move to the end of the buffer (`end-of-buffer'). `M-x goto-char' Read a number N and move the cursor to character number N. Position 1 is the beginning of the buffer. `M-g' Read a number N and move cursor to line number N (`goto-line'). Line 1 is the beginning of the buffer. `C-x C-n' Use the current column of point as the "semi-permanent goal column" for `C-n' and `C-p' (`set-goal-column'). Henceforth, those commands always move to this column in each line moved into, or as close as possible given the contents of the line. This goal column remains in effect until canceled. `C-u C-x C-n' Cancel the goal column. Henceforth, `C-n' and `C-p' once again try to avoid changing the horizontal position, as usual. If you set the variable `track-eol' to a non-`nil' value, `C-n' and `C-p' move to the end of the line when at the end of the starting line. By default, `track-eol' is `nil'. Erasing Text ============ `<DEL>' Delete the character before the cursor (`delete-backward-char'). `C-d' Delete the character after the cursor (`delete-char'). `C-k' Kill to the end of the line (`kill-line'). `M-d' Kill forward to the end of the next word (`kill-word'). `M-<DEL>' Kill back to the beginning of the previous word (`backward-kill-word'). In contrast to the <DEL> key, which deletes the character before the cursor, `Control-d' deletes the character after the cursor, causing the rest of the text on the line to shift left. If `Control-d' is typed at the end of a line, that line and the next line are joined. To erase a larger amount of text, use `Control-k', which kills a line at a time. If you use `C-k' at the beginning or in the middle of a line, it kills all the text up to the end of the line. If you use `C-k' at the end of a line, it joins that line and the next line. *Note Killing::, for more flexible ways of killing text. Files ===== The commands above are sufficient for creating and altering text in an Emacs buffer. More advanced Emacs commands just make things easier. But to keep any text permanently you must put it in a "file". Files are named units of text which are stored by the operating system and which you can retrieve by name. To look at or use the contents of a file in any way, including editing the file with Emacs, you must specify the file name. Consider a file named `/usr/rms/foo.c'. To begin editing this file from Emacs, type: C-x C-f /usr/rms/foo.c <RET> The file name is given as an "argument" to the command `C-x C-f' (`find-file'). The command uses the "minibuffer" to read the argument. You have to type <RET> to terminate the argument (*note Minibuffer::.). You can also use the Open... menu item from the File menu, then type the name of the file to the prompt. Emacs obeys the command by "visiting" the file: it creates a buffer, copies the contents of the file into the buffer, and then displays the buffer for you to edit. You can make changes in the buffer, and then "save" the file by typing `C-x C-s' (`save-buffer') or choosing Save Buffer from the File menu. This makes the changes permanent by copying the altered contents of the buffer back into the file `/usr/rms/foo.c'. Until then, the changes are only inside your Emacs buffer, and the file `foo.c' is not changed. To create a file, visit the file with `C-x C-f' as if it already existed or choose Open... from the File menu and provide the name for the new file in the minibuffer. Emacs will create an empty buffer in which you can insert the text you want to put in the file. When you save the buffer with `C-x C-s', or by choosing Save Buffer from the File menu, the file is created. To learn more about using files, *note Files::.. Help ==== If you forget what a key does, you can use the Help character (`C-h') to find out: Type `C-h k' followed by the key you want to know about. For example, `C-h k C-n' tells you what `C-n' does. `C-h' is a prefix key; `C-h k' is just one of its subcommands (the command `describe-key'). The other subcommands of `C-h' provide different kinds of help. Type `C-h' three times to get a description of all the help facilities. *Note Help::. * Menu: * Blank Lines:: Commands to make or delete blank lines. * Continuation Lines:: Lines too wide for the frame. * Position Info:: What page, line, row, or column is point on? * Arguments:: Numeric arguments for repeating a command. File: xemacs.info, Node: Blank Lines, Next: Continuation Lines, Prev: Basic, Up: Basic Blank Lines =========== Here are special commands and techniques for entering and removing blank lines. `C-o' Insert one or more blank lines after the cursor (`open-line'). `C-x C-o' Delete all but one of many consecutive blank lines (`delete-blank-lines'). When you want to insert a new line of text before an existing line, you just type the new line of text, followed by <RET>. If you prefer to create a blank line first and then insert the desired text, use the key `C-o' (`open-line'), which inserts a newline after point but leaves point in front of the newline. Then type the text into the new line. `C-o F O O' has the same effect as `F O O <RET>', except for the final location of point. To create several blank lines, type `C-o' several times, or give `C-o' an argument indicating how many blank lines to create. *Note Arguments::, for more information. If you have many blank lines in a row and want to get rid of them, use `C-x C-o' (`delete-blank-lines'). If point is on a blank line which is adjacent to at least one other blank line, `C-x C-o' deletes all but one of the blank lines. If point is on a blank line with no other adjacent blank line, the sole blank line is deleted. If point is on a non-blank line, `C-x C-o' deletes any blank lines following that non-blank line. File: xemacs.info, Node: Continuation Lines, Next: Position Info, Prev: Blank Lines, Up: Basic Continuation Lines ================== If you add too many characters to one line without breaking with a <RET>, the line grows to occupy two (or more) screen lines, with a curved arrow at the extreme right margin of all but the last line. The curved arrow indicates that the following screen line is not really a distinct line in the text, but just the "continuation" of a line too long to fit the frame. You can use Auto Fill mode (*note Filling::.) to have Emacs insert newlines automatically when a line gets too long. Instead of continuation, long lines can be displayed by "truncation". This means that all the characters that do not fit in the width of the frame or window do not appear at all. They remain in the buffer, temporarily invisible. Three diagonal dots in the last column (instead of the curved arrow inform you that truncation is in effect. To turn off continuation for a particular buffer, set the variable `truncate-lines' to non-`nil' in that buffer. Truncation instead of continuation also happens whenever horizontal scrolling is in use, and optionally whenever side-by-side windows are in use (*note Windows::.). Altering the value of `truncate-lines' makes it local to the current buffer; until that time, the default value is in effect. The default is initially `nil'. *Note Locals::. File: xemacs.info, Node: Position Info, Next: Arguments, Prev: Continuation Lines, Up: Basic Cursor Position Information =========================== If you are accustomed to other display editors, you may be surprised that Emacs does not always display the page number or line number of point in the mode line. In Emacs, this information is only rarely needed, and a number of commands are available to compute and print it. Since text is stored in a way that makes it difficult to compute the information, it is not displayed all the time. `M-x what-page' Print page number of point, and line number within page. `M-x what-line' Print line number of point in the buffer. `M-=' Print number of lines and characters in the current region (`count-lines-region'). `C-x =' Print character code of character after point, character position of point, and column of point (`what-cursor-position'). There are several commands for printing line numbers: * `M-x what-line' counts lines from the beginning of the file and prints the line number point is on. The first line of the file is line number 1. You can use these numbers as arguments to `M-x goto-line'. * `M-x what-page' counts pages from the beginning of the file, and counts lines within the page, printing both of them. *Note Pages::, for the command `C-x l', which counts the lines in the current page. * `M-=' (`count-lines-region') prints the number of lines in the region (*note Mark::.). The command `C-x =' (`what-cursor-position') provides information about point and about the column the cursor is in. It prints a line in the echo area that looks like this: Char: x (0170) point=65986 of 563027(12%) column 44 (In fact, this is the output produced when point is before `column 44' in the example.) The two values after `Char:' describe the character following point, first by showing it and second by giving its octal character code. `point=' is followed by the position of point expressed as a character count. The front of the buffer counts as position 1, one character later as 2, and so on. The next, larger number is the total number of characters in the buffer. Afterward in parentheses comes the position expressed as a percentage of the total size. `column' is followed by the horizontal position of point, in columns from the left edge of the window. If the buffer has been narrowed, making some of the text at the beginning and the end temporarily invisible, `C-x =' prints additional text describing the current visible range. For example, it might say: Char: x (0170) point=65986 of 563025(12%) <65102 - 68533> column 44 where the two extra numbers give the smallest and largest character position that point is allowed to assume. The characters between those two positions are the visible ones. *Note Narrowing::. If point is at the end of the buffer (or the end of the visible part), `C-x =' omits any description of the character after point. The output looks like point=563026 of 563025(100%) column 0 File: xemacs.info, Node: Arguments, Prev: Position Info, Up: Basic Numeric Arguments ================= Any Emacs command can be given a "numeric argument". Some commands interpret the argument as a repetition count. For example, giving an argument of ten to the key `C-f' (the command `forward-char', move forward one character) moves forward ten characters. With these commands, no argument is equivalent to an argument of one. Negative arguments are allowed. Often they tell a command to move or act backwards. If your keyboard has a <META> key (labelled with a diamond on Sun-type keyboards and labelled `Alt' on some other keyboards), the easiest way to specify a numeric argument is to type digits and/or a minus sign while holding down the <META> key. For example, M-5 C-n moves down five lines. The characters `Meta-1', `Meta-2', and so on, as well as `Meta--', do this because they are keys bound to commands (`digit-argument' and `negative-argument') that are defined to contribute to an argument for the next command. Another way of specifying an argument is to use the `C-u' (`universal-argument') command followed by the digits of the argument. With `C-u', you can type the argument digits without holding down shift keys. To type a negative argument, start with a minus sign. Just a minus sign normally means -1. `C-u' works on all terminals. `C-u' followed by a character which is neither a digit nor a minus sign has the special meaning of "multiply by four". It multiplies the argument for the next command by four. `C-u' twice multiplies it by sixteen. Thus, `C-u C-u C-f' moves forward sixteen characters. This is a good way to move forward "fast", since it moves about 1/5 of a line in the usual size frame. Other useful combinations are `C-u C-n', `C-u C-u C-n' (move down a good fraction of a frame), `C-u C-u C-o' (make "a lot" of blank lines), and `C-u C-k' (kill four lines). Some commands care only about whether there is an argument and not about its value. For example, the command `M-q' (`fill-paragraph') with no argument fills text; with an argument, it justifies the text as well. (*Note Filling::, for more information on `M-q'.) Just `C-u' is a handy way of providing an argument for such commands. Some commands use the value of the argument as a repeat count, but do something peculiar when there is no argument. For example, the command `C-k' (`kill-line') with argument N kills N lines, including their terminating newlines. But `C-k' with no argument is special: it kills the text up to the next newline, or, if point is right at the end of the line, it kills the newline itself. Thus, two `C-k' commands with no arguments can kill a non-blank line, just like `C-k' with an argument of one. (*Note Killing::, for more information on `C-k'.) A few commands treat a plain `C-u' differently from an ordinary argument. A few others may treat an argument of just a minus sign differently from an argument of -1. These unusual cases will be described when they come up; they are always to make the individual command more convenient to use. File: xemacs.info, Node: Undo, Next: Minibuffer, Prev: Basic, Up: Top Undoing Changes *************** Emacs allows you to undo all changes you make to the text of a buffer, up to a certain amount of change (8000 characters). Each buffer records changes individually, and the undo command always applies to the current buffer. Usually each editing command makes a separate entry in the undo records, but some commands such as `query-replace' make many entries, and very simple commands such as self-inserting characters are often grouped to make undoing less tedious. `C-x u' Undo one batch of changes (usually, one command's worth) (`undo'). `C-_' The same. The command `C-x u' or `C-_' allows you to undo changes. The first time you give this command, it undoes the last change. Point moves to the text affected by the undo, so you can see what was undone. Consecutive repetitions of the `C-_' or `C-x u' commands undo earlier and earlier changes, back to the limit of what has been recorded. If all recorded changes have already been undone, the undo command prints an error message and does nothing. Any command other than an undo command breaks the sequence of undo commands. Starting at this moment, the previous undo commands are considered ordinary changes that can themselves be undone. Thus, you can redo changes you have undone by typing `C-f' or any other command that have no important effect, and then using more undo commands. If you notice that a buffer has been modified accidentally, the easiest way to recover is to type `C-_' repeatedly until the stars disappear from the front of the mode line. When that happens, all the modifications you made have been canceled. If you do not remember whether you changed the buffer deliberately, type `C-_' once. When you see Emacs undo the last change you made, you probably remember why you made it. If the change was an accident, leave it undone. If it was deliberate, redo the change as described in the preceding paragraph. Whenever an undo command makes the stars disappear from the mode line, the buffer contents is the same as it was when the file was last read in or saved. Not all buffers record undo information. Buffers whose names start with spaces don't; these buffers are used internally by Emacs and its extensions to hold text that users don't normally look at or edit. Minibuffers, help buffers, and documentation buffers also don't record undo information. Emacs can remember at most 8000 or so characters of deleted or modified text in any one buffer for reinsertion by the undo command. There is also a limit on the number of individual insert, delete, or change actions that Emacs can remember. There are two keys to run the `undo' command, `C-x u' and `C-_', because on some keyboards, it is not obvious how to type `C-_'. `C-x u' is an alternative you can type in the same fashion on any terminal. File: xemacs.info, Node: Minibuffer, Next: M-x, Prev: Undo, Up: Top The Minibuffer ************** Emacs commands use the "minibuffer" to read arguments more complicated than a single number. Minibuffer arguments can be file names, buffer names, Lisp function names, Emacs command names, Lisp expressions, and many other things, depending on the command reading the argument. To edit the argument in the minibuffer, you can use Emacs editing commands. When the minibuffer is in use, it appears in the echo area, and the cursor moves there. The beginning of the minibuffer line displays a "prompt" indicating what kind of input you should supply and how it will be used. The prompt is often derived from the name of the command the argument is for. The prompt normally ends with a colon. Sometimes a "default argument" appears in parentheses after the colon; it, too, is part of the prompt. The default is used as the argument value if you enter an empty argument (e.g., by just typing <RET>). For example, commands that read buffer names always show a default, which is the name of the buffer that will be used if you type just <RET>. The simplest way to give a minibuffer argument is to type the text you want, terminated by <RET> to exit the minibuffer. To get out of the minibuffer and cancel the command that it was for, type `C-g'. Since the minibuffer uses the screen space of the echo area, it can conflict with other ways Emacs customarily uses the echo area. Here is how Emacs handles such conflicts: * If a command gets an error while you are in the minibuffer, this does not cancel the minibuffer. However, the echo area is needed for the error message and therefore the minibuffer itself is hidden for a while. It comes back after a few seconds, or as soon as you type anything. * If you use a command in the minibuffer whose purpose is to print a message in the echo area (for example `C-x =') the message is displayed normally, and the minibuffer is hidden for a while. It comes back after a few seconds, or as soon as you type anything. * Echoing of keystrokes does not take place while the minibuffer is in use. * Menu: * File: Minibuffer File. Entering file names with the minibuffer. * Edit: Minibuffer Edit. How to edit in the minibuffer. * Completion:: An abbreviation facility for minibuffer input. * Repetition:: Re-executing commands that used the minibuffer. File: xemacs.info, Node: Minibuffer File, Next: Minibuffer Edit, Prev: Minibuffer, Up: Minibuffer Minibuffers for File Names ========================== Sometimes the minibuffer starts out with text in it. For example, when you are supposed to give a file name, the minibuffer starts out containing the "default directory", which ends with a slash. This informs you in which directory the file will be looked for if you do not specify a different one. For example, the minibuffer might start out with: Find File: /u2/emacs/src/ where `Find File: ' is the prompt. Typing `buffer.c' specifies the file `/u2/emacs/src/buffer.c'. To find files in nearby directories, use `..'; thus, if you type `../lisp/simple.el', the file that you visit will be the one named `/u2/emacs/lisp/simple.el'. Alternatively, you can use `M-<DEL>' to kill directory names you don't want (*note Words::.). You can also type an absolute file name, one starting with a slash or a tilde, ignoring the default directory. For example, to find the file `/etc/termcap', just type the name, giving: Find File: /u2/emacs/src//etc/termcap Two slashes in a row are not normally meaningful in Unix file names, but they are allowed in XEmacs. They mean, "ignore everything before the second slash in the pair." Thus, `/u2/emacs/src/' is ignored, and you get the file `/etc/termcap'. If you set `insert-default-directory' to `nil', the default directory is not inserted in the minibuffer. This way, the minibuffer starts out empty. But the name you type, if relative, is still interpreted with respect to the same default directory. File: xemacs.info, Node: Minibuffer Edit, Next: Completion, Prev: Minibuffer File, Up: Minibuffer Editing in the Minibuffer ========================= The minibuffer is an Emacs buffer (albeit a peculiar one), and the usual Emacs commands are available for editing the text of an argument you are entering. Since <RET> in the minibuffer is defined to exit the minibuffer, you must use `C-o' or `C-q <LFD>' to insert a newline into the minibuffer. (Recall that a newline is really the <LFD> character.) The minibuffer has its own window, which always has space on the screen but acts as if it were not there when the minibuffer is not in use. The minibuffer window is just like the others; you can switch to another window with `C-x o', edit text in other windows, and perhaps even visit more files before returning to the minibuffer to submit the argument. You can kill text in another window, return to the minibuffer window, and then yank the text to use it in the argument. *Note Windows::. There are, however, some restrictions on the use of the minibuffer window. You cannot switch buffers in it--the minibuffer and its window are permanently attached. You also cannot split or kill the minibuffer window, but you can make it taller with `C-x ^'. If you are in the minibuffer and issue a command that displays help text in another window, that window will be scrolled if you type `M-C-v' while in the minibuffer until you exit the minibuffer. This feature is helpful if a completing minibuffer gives you a long list of possible completions. If the variable `minibuffer-confirm-incomplete' is `t', you are asked for confirmation if there is no known completion for the text you typed. For example, if you attempted to visit a non-existent file, the minibuffer might read: Find File:chocolate_bar.c [no completions, confirm] If you press `Return' again, that confirms the filename. Otherwise, you can continue editing it. Emacs supports recursive use of the minibuffer. However, it is easy to do this by accident (because of autorepeating keyboards, for example) and get confused. Therefore, most Emacs commands that use the minibuffer refuse to operate if the minibuffer window is selected. If the minibuffer is active but you have switched to a different window, recursive use of the minibuffer is allowed--if you know enough to try to do this, you probably will not get confused. If you set the variable `enable-recursive-minibuffers' to be non-`nil', recursive use of the minibuffer is always allowed. File: xemacs.info, Node: Completion, Next: Repetition, Prev: Minibuffer Edit, Up: Minibuffer Completion ========== When appropriate, the minibuffer provides a "completion" facility. You type the beginning of an argument and one of the completion keys, and Emacs visibly fills in the rest, depending on what you have already typed. When completion is available, certain keys--<TAB>, <RET>, and <SPC>--are redefined to complete an abbreviation present in the minibuffer into a longer string that it stands for, by matching it against a set of "completion alternatives" provided by the command reading the argument. `?' is defined to display a list of possible completions of what you have inserted. For example, when the minibuffer is being used by `Meta-x' to read the name of a command, it is given a list of all available Emacs command names to complete against. The completion keys match the text in the minibuffer against all the command names, find any additional characters of the name that are implied by the ones already present in the minibuffer, and add those characters to the ones you have given. Case is normally significant in completion because it is significant in most of the names that you can complete (buffer names, file names, and command names). Thus, `fo' will not complete to `Foo'. When you are completing a name in which case does not matter, case may be ignored for completion's sake if specified by program. When a completion list is displayed, the completions will highlight as you move the mouse over them. Clicking the middle mouse button on any highlighted completion will "select" it just as if you had typed it in and hit <RET>. A Completion Example -------------------- Consider the following example. If you type `Meta-x au <TAB>', <TAB> looks for alternatives (in this case, command names) that start with `au'. There are only two commands: `auto-fill-mode' and `auto-save-mode'. They are the same as far as `auto-', so the `au' in the minibuffer changes to `auto-'. If you type <TAB> again immediately, there are multiple possibilities for the very next character--it could be `s' or `f'--so no more characters are added; but a list of all possible completions is displayed in another window. If you go on to type `f <TAB>', this <TAB> sees `auto-f'. The only command name starting this way is `auto-fill-mode', so completion inserts the rest of that command. You now have `auto-fill-mode' in the minibuffer after typing just `au <TAB> f <TAB>'. Note that <TAB> has this effect because in the minibuffer it is bound to the function `minibuffer-complete' when completion is supposed to be done. Completion Commands ------------------- Here is a list of all the completion commands defined in the minibuffer when completion is available. `<TAB>' Complete the text in the minibuffer as much as possible (`minibuffer-complete'). `<SPC>' Complete the text in the minibuffer but don't add or fill out more than one word (`minibuffer-complete-word'). `<RET>' Submit the text in the minibuffer as the argument, possibly completing first as described below (`minibuffer-complete-and-exit'). `?' Print a list of all possible completions of the text in the minibuffer (`minibuffer-list-completions'). `<button2>' Select the highlighted text under the mouse as a minibuffer response. When the minibuffer is being used to prompt the user for a completion, any valid completions which are visible on the screen will be highlighted when the mouse moves over them. Clicking <button2> will select the highlighted completion and exit the minibuffer. (`minibuf-select-highlighted-completion'). <SPC> completes in a way that is similar to <TAB>, but it never goes beyond the next hyphen or space. If you have `auto-f' in the minibuffer and type <SPC>, it finds that the completion is `auto-fill-mode', but it stops completing after `fill-'. The result is `auto-fill-'. Another <SPC> at this point completes all the way to `auto-fill-mode'. <SPC> in the minibuffer runs the function `minibuffer-complete-word' when completion is available. There are three different ways that <RET> can work in completing minibuffers, depending on how the argument will be used. * "Strict" completion is used when it is meaningless to give any argument except one of the known alternatives. For example, when `C-x k' reads the name of a buffer to kill, it is meaningless to give anything but the name of an existing buffer. In strict completion, <RET> refuses to exit if the text in the minibuffer does not complete to an exact match. * "Cautious" completion is similar to strict completion, except that <RET> exits only if the text was an exact match already, not needing completion. If the text is not an exact match, <RET> does not exit, but it does complete the text. If it completes to an exact match, a second <RET> will exit. Cautious completion is used for reading file names for files that must already exist. * "Permissive" completion is used when any string is meaningful, and the list of completion alternatives is just a guide. For example, when `C-x C-f' reads the name of a file to visit, any file name is allowed, in case you want to create a file. In permissive completion, <RET> takes the text in the minibuffer exactly as given, without completing it. The completion commands display a list of all possible completions in a window whenever there is more than one possibility for the very next character. Typing `?' explicitly requests such a list. The list of completions counts as help text, so `C-M-v' typed in the minibuffer scrolls the list. When completion is done on file names, certain file names are usually ignored. The variable `completion-ignored-extensions' contains a list of strings; a file whose name ends in any of those strings is ignored as a possible completion. The standard value of this variable has several elements including `".o"', `".elc"', `".dvi"' and `"~"'. The effect is that, for example, `foo' completes to `foo.c' even though `foo.o' exists as well. If the only possible completions are files that end in "ignored" strings, they are not ignored. If a completion command finds the next character is undetermined, it automatically displays a list of all possible completions. If the variable `completion-auto-help' is set to `nil', this does not happen, and you must type `?' to display the possible completions. If the variable `minibuffer-confirm-incomplete' is set to `t', then in contexts where `completing-read' allows answers that are not valid completions, an extra <RET> must be typed to confirm the response. This is helpful for catching typos. File: xemacs.info, Node: Repetition, Prev: Completion, Up: Minibuffer Repeating Minibuffer Commands ============================= Every command that uses the minibuffer at least once is recorded on a special history list, together with the values of the minibuffer arguments, so that you can repeat the command easily. In particular, every use of `Meta-x' is recorded, since `M-x' uses the minibuffer to read the command name. `C-x <ESC>' Re-execute a recent minibuffer command (`repeat-complex-command'). `M-p' Within `C-x <ESC>', move to previous recorded command (`previous-history-element'). `M-n' Within `C-x <ESC>', move to the next (more recent) recorded command (`next-history-element'). `M-x list-command-history' Display the entire command history, showing all the commands `C-x <ESC>' can repeat, most recent first. `C-x <ESC>' is used to re-execute a recent command that used the minibuffer. With no argument, it repeats the last command. A numeric argument specifies which command to repeat; 1 means the last one, and larger numbers specify earlier commands. `C-x <ESC>' works by turning the previous command into a Lisp expression and then entering a minibuffer initialized with the text for that expression. If you type just <RET>, the command is repeated as before. You can also change the command by editing the Lisp expression. The expression you finally submit will be executed. The repeated command is added to the front of the command history unless it is identical to the most recently executed command already there. Even if you don't understand Lisp syntax, it will probably be obvious which command is displayed for repetition. If you do not change the text, you can be sure the command will repeat exactly as before. If you are in the minibuffer for `C-x <ESC>' and the command shown to you is not the one you want to repeat, you can move around the list of previous commands using `M-n' and `M-p'. `M-p' replaces the contents of the minibuffer with the next earlier recorded command, and `M-n' replaces it with the next later command. After finding the desired previous command, you can edit its expression and then resubmit it by typing <RET>. Any editing you have done on the command to be repeated is lost if you use `M-n' or `M-p'. `M-n' and `M-p' are specially defined within `C-x <ESC>' to run the commands `previous-history-element' and `next-history-element'. The list of previous commands using the minibuffer is stored as a Lisp list in the variable `command-history'. Each element of the list is a Lisp expression which describes one command and its arguments. Lisp programs can reexecute a command by feeding the corresponding `command-history' element to `eval'.