This is Info file ../info/emacs, produced by Makeinfo version 1.68 from the input file ../texi/emacs.texi. This is the thirteenth edition of the `GNU Emacs Manual', updated for Emacs version 20.7. INFO-DIR-SECTION Editors START-INFO-DIR-ENTRY * Emacs: (emacs). The extensible self-documenting text editor. END-INFO-DIR-ENTRY Published by the Free Software Foundation 59 Temple Place, Suite 330 Boston, MA 02111-1307 USA Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1996, 1997, 1998, 1999 Free Software Foundation, Inc. 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 Free Software Foundation instead of in the original English.  File: emacs, Node: Incremental Search, Next: Nonincremental Search, Prev: Search, Up: Search Incremental Search ================== An incremental search begins searching as soon as you type the first character of the search string. As you type in the search string, Emacs shows you where the string (as you have typed it so far) would be found. When you have typed enough characters to identify the place you want, you can stop. Depending on what you plan to do next, you may or may not need to terminate the search explicitly with . `C-s' Incremental search forward (`isearch-forward'). `C-r' Incremental search backward (`isearch-backward'). `C-s' starts an incremental search. `C-s' reads characters from the keyboard and positions the cursor at the first occurrence of the characters that you have typed. If you type `C-s' and then `F', the cursor moves right after the first `F'. Type an `O', and see the cursor move to after the first `FO'. After another `O', the cursor is after the first `FOO' after the place where you started the search. At each step, the buffer text that matches the search string is highlighted, if the terminal can do that; at each step, the current search string is updated in the echo area. If you make a mistake in typing the search string, you can cancel characters with . Each cancels the last character of search string. This does not happen until Emacs is ready to read another input character; first it must either find, or fail to find, the character you want to erase. If you do not want to wait for this to happen, use `C-g' as described below. When you are satisfied with the place you have reached, you can type , which stops searching, leaving the cursor where the search brought it. Also, any command not specially meaningful in searches stops the searching and is then executed. Thus, typing `C-a' would exit the search and then move to the beginning of the line. is necessary only if the next command you want to type is a printing character, , , or another control character that is special within searches (`C-q', `C-w', `C-r', `C-s', `C-y', `M-y', `M-r', or `M-s'). Sometimes you search for `FOO' and find it, but not the one you expected to find. There was a second `FOO' that you forgot about, before the one you were aiming for. In this event, type another `C-s' to move to the next occurrence of the search string. This can be done any number of times. If you overshoot, you can cancel some `C-s' characters with . After you exit a search, you can search for the same string again by typing just `C-s C-s': the first `C-s' is the key that invokes incremental search, and the second `C-s' means "search again." To reuse earlier search strings, use the "search ring". The commands `M-p' and `M-n' move through the ring to pick a search string to reuse. These commands leave the selected search ring element in the minibuffer, where you can edit it. Type `C-s' or `C-r' to terminate editing the string and search for it. If your string is not found at all, the echo area says `Failing I-Search'. The cursor is after the place where Emacs found as much of your string as it could. Thus, if you search for `FOOT', and there is no `FOOT', you might see the cursor after the `FOO' in `FOOL'. At this point there are several things you can do. If your string was mistyped, you can rub some of it out and correct it. If you like the place you have found, you can type or some other Emacs command to "accept what the search offered." Or you can type `C-g', which removes from the search string the characters that could not be found (the `T' in `FOOT'), leaving those that were found (the `FOO' in `FOOT'). A second `C-g' at that point cancels the search entirely, returning point to where it was when the search started. An upper-case letter in the search string makes the search case-sensitive. If you delete the upper-case character from the search string, it ceases to have this effect. *Note Search Case::. If a search is failing and you ask to repeat it by typing another `C-s', it starts again from the beginning of the buffer. Repeating a failing reverse search with `C-r' starts again from the end. This is called "wrapping around". `Wrapped' appears in the search prompt once this has happened. If you keep on going past the original starting point of the search, it changes to `Overwrapped', which means that you are revisiting matches that you have already seen. The `C-g' "quit" character does special things during searches; just what it does depends on the status of the search. If the search has found what you specified and is waiting for input, `C-g' cancels the entire search. The cursor moves back to where you started the search. If `C-g' is typed when there are characters in the search string that have not been found--because Emacs is still searching for them, or because it has failed to find them--then the search string characters which have not been found are discarded from the search string. With them gone, the search is now successful and waiting for more input, so a second `C-g' will cancel the entire search. To search for a newline, type `C-j'. To search for another control character, such as control-S or carriage return, you must quote it by typing `C-q' first. This function of `C-q' is analogous to its use for insertion (*note Inserting Text::.): it causes the following character to be treated the way any "ordinary" character is treated in the same context. You can also specify a character by its octal code: enter `C-q' followed by a sequence of octal digits. You can change to searching backwards with `C-r'. If a search fails because the place you started was too late in the file, you should do this. Repeated `C-r' keeps looking for more occurrences backwards. A `C-s' starts going forwards again. `C-r' in a search can be canceled with . If you know initially that you want to search backwards, you can use `C-r' instead of `C-s' to start the search, because `C-r' as a key runs a command (`isearch-backward') to search backward. A backward search finds matches that are entirely before the starting point, just as a forward search finds matches that begin after it. The characters `C-y' and `C-w' can be used in incremental search to grab text from the buffer into the search string. This makes it convenient to search for another occurrence of text at point. `C-w' copies the word after point as part of the search string, advancing point over that word. Another `C-s' to repeat the search will then search for a string including that word. `C-y' is similar to `C-w' but copies all the rest of the current line into the search string. Both `C-y' and `C-w' convert the text they copy to lower case if the search is currently not case-sensitive; this is so the search remains case-insensitive. The character `M-y' copies text from the kill ring into the search string. It uses the same text that `C-y' as a command would yank. *Note Yanking::. When you exit the incremental search, it sets the mark to where point *was*, before the search. That is convenient for moving back there. In Transient Mark mode, incremental search sets the mark without activating it, and does so only if the mark is not already active. To customize the special characters that incremental search understands, alter their bindings in the keymap `isearch-mode-map'. For a list of bindings, look at the documentation of `isearch-mode' with `C-h f isearch-mode '. Slow Terminal Incremental Search -------------------------------- Incremental search on a slow terminal uses a modified style of display that is designed to take less time. Instead of redisplaying the buffer at each place the search gets to, it creates a new single-line window and uses that to display the line that the search has found. The single-line window comes into play as soon as point gets outside of the text that is already on the screen. When you terminate the search, the single-line window is removed. Then Emacs redisplays the window in which the search was done, to show its new position of point. The slow terminal style of display is used when the terminal baud rate is less than or equal to the value of the variable `search-slow-speed', initially 1200. The number of lines to use in slow terminal search display is controlled by the variable `search-slow-window-lines'. Its normal value is 1.  File: emacs, Node: Nonincremental Search, Next: Word Search, Prev: Incremental Search, Up: Search Nonincremental Search ===================== Emacs also has conventional nonincremental search commands, which require you to type the entire search string before searching begins. `C-s STRING ' Search for STRING. `C-r STRING ' Search backward for STRING. To do a nonincremental search, first type `C-s '. This enters the minibuffer to read the search string; terminate the string with , and then the search takes place. If the string is not found, the search command gets an error. The way `C-s ' works is that the `C-s' invokes incremental search, which is specially programmed to invoke nonincremental search if the argument you give it is empty. (Such an empty argument would otherwise be useless.) `C-r ' also works this way. However, nonincremental searches performed using `C-s ' do not call `search-forward' right away. The first thing done is to see if the next character is `C-w', which requests a word search. *Note Word Search::. Forward and backward nonincremental searches are implemented by the commands `search-forward' and `search-backward'. These commands may be bound to keys in the usual manner. The feature that you can get to them via the incremental search commands exists for historical reasons, and to avoid the need to find suitable key sequences for them.  File: emacs, Node: Word Search, Next: Regexp Search, Prev: Nonincremental Search, Up: Search Word Search =========== Word search searches for a sequence of words without regard to how the words are separated. More precisely, you type a string of many words, using single spaces to separate them, and the string can be found even if there are multiple spaces, newlines or other punctuation between the words. Word search is useful for editing a printed document made with a text formatter. If you edit while looking at the printed, formatted version, you can't tell where the line breaks are in the source file. With word search, you can search without having to know them. `C-s C-w WORDS ' Search for WORDS, ignoring details of punctuation. `C-r C-w WORDS ' Search backward for WORDS, ignoring details of punctuation. Word search is a special case of nonincremental search and is invoked with `C-s C-w'. This is followed by the search string, which must always be terminated with . Being nonincremental, this search does not start until the argument is terminated. It works by constructing a regular expression and searching for that; see *Note Regexp Search::. Use `C-r C-w' to do backward word search. Forward and backward word searches are implemented by the commands `word-search-forward' and `word-search-backward'. These commands may be bound to keys in the usual manner. The feature that you can get to them via the incremental search commands exists for historical reasons, and to avoid the need to find suitable key sequences for them.  File: emacs, Node: Regexp Search, Next: Regexps, Prev: Word Search, Up: Search Regular Expression Search ========================= A "regular expression" ("regexp", for short) is a pattern that denotes a class of alternative strings to match, possibly infinitely many. In GNU Emacs, you can search for the next match for a regexp either incrementally or not. Incremental search for a regexp is done by typing `C-M-s' (`isearch-forward-regexp'). This command reads a search string incrementally just like `C-s', but it treats the search string as a regexp rather than looking for an exact match against the text in the buffer. Each time you add text to the search string, you make the regexp longer, and the new regexp is searched for. Invoking `C-s' with a prefix argument (its value does not matter) is another way to do a forward incremental regexp search. To search backward for a regexp, use `C-M-r' (`isearch-backward-regexp'), or `C-r' with a prefix argument. All of the control characters that do special things within an ordinary incremental search have the same function in incremental regexp search. Typing `C-s' or `C-r' immediately after starting the search retrieves the last incremental search regexp used; that is to say, incremental regexp and non-regexp searches have independent defaults. They also have separate search rings that you can access with `M-p' and `M-n'. If you type in incremental regexp search, it matches any sequence of whitespace characters, including newlines. If you want to match just a space, type `C-q '. Note that adding characters to the regexp in an incremental regexp search can make the cursor move back and start again. For example, if you have searched for `foo' and you add `\|bar', the cursor backs up in case the first `bar' precedes the first `foo'. Nonincremental search for a regexp is done by the functions `re-search-forward' and `re-search-backward'. You can invoke these with `M-x', or bind them to keys, or invoke them by way of incremental regexp search with `C-M-s ' and `C-M-r '. If you use the incremental regexp search commands with a prefix argument, they perform ordinary string search, like `isearch-forward' and `isearch-backward'. *Note Incremental Search::.  File: emacs, Node: Regexps, Next: Search Case, Prev: Regexp Search, Up: Search Syntax of Regular Expressions ============================= Regular expressions have a syntax in which a few characters are special constructs and the rest are "ordinary". An ordinary character is a simple regular expression which matches that same character and nothing else. The special characters are `$', `^', `.', `*', `+', `?', `[', `]' and `\'. Any other character appearing in a regular expression is ordinary, unless a `\' precedes it. For example, `f' is not a special character, so it is ordinary, and therefore `f' is a regular expression that matches the string `f' and no other string. (It does *not* match the string `ff'.) Likewise, `o' is a regular expression that matches only `o'. (When case distinctions are being ignored, these regexps also match `F' and `O', but we consider this a generalization of "the same string," rather than an exception.) Any two regular expressions A and B can be concatenated. The result is a regular expression which matches a string if A matches some amount of the beginning of that string and B matches the rest of the string. As a simple example, we can concatenate the regular expressions `f' and `o' to get the regular expression `fo', which matches only the string `fo'. Still trivial. To do something nontrivial, you need to use one of the special characters. Here is a list of them. `. (Period)' is a special character that matches any single character except a newline. Using concatenation, we can make regular expressions like `a.b', which matches any three-character string that begins with `a' and ends with `b'. `*' is not a construct by itself; it is a postfix operator that means to match the preceding regular expression repetitively as many times as possible. Thus, `o*' matches any number of `o's (including no `o's). `*' always applies to the *smallest* possible preceding expression. Thus, `fo*' has a repeating `o', not a repeating `fo'. It matches `f', `fo', `foo', and so on. The matcher processes a `*' construct by matching, immediately, as many repetitions as can be found. Then it continues with the rest of the pattern. If that fails, backtracking occurs, discarding some of the matches of the `*'-modified construct in case that makes it possible to match the rest of the pattern. For example, in matching `ca*ar' against the string `caaar', the `a*' first tries to match all three `a's; but the rest of the pattern is `ar' and there is only `r' left to match, so this try fails. The next alternative is for `a*' to match only two `a's. With this choice, the rest of the regexp matches successfully. `+' is a postfix operator, similar to `*' except that it must match the preceding expression at least once. So, for example, `ca+r' matches the strings `car' and `caaaar' but not the string `cr', whereas `ca*r' matches all three strings. `?' is a postfix operator, similar to `*' except that it can match the preceding expression either once or not at all. For example, `ca?r' matches `car' or `cr'; nothing else. `[ ... ]' is a "character set", which begins with `[' and is terminated by `]'. In the simplest case, the characters between the two brackets are what this set can match. Thus, `[ad]' matches either one `a' or one `d', and `[ad]*' matches any string composed of just `a's and `d's (including the empty string), from which it follows that `c[ad]*r' matches `cr', `car', `cdr', `caddaar', etc. You can also include character ranges in a character set, by writing the starting and ending characters with a `-' between them. Thus, `[a-z]' matches any lower-case ASCII letter. Ranges may be intermixed freely with individual characters, as in `[a-z$%.]', which matches any lower-case ASCII letter or `$', `%' or period. Note that the usual regexp special characters are not special inside a character set. A completely different set of special characters exists inside character sets: `]', `-' and `^'. To include a `]' in a character set, you must make it the first character. For example, `[]a]' matches `]' or `a'. To include a `-', write `-' as the first or last character of the set, or put it after a range. Thus, `[]-]' matches both `]' and `-'. To include `^' in a set, put it anywhere but at the beginning of the set. When you use a range in case-insensitive search, you should write both ends of the range in upper case, or both in lower case, or both should be non-letters. The behavior of a mixed-case range such as `A-z' is somewhat ill-defined, and it may change in future Emacs versions. `[^ ... ]' `[^' begins a "complemented character set", which matches any character except the ones specified. Thus, `[^a-z0-9A-Z]' matches all characters *except* letters and digits. `^' is not special in a character set unless it is the first character. The character following the `^' is treated as if it were first (in other words, `-' and `]' are not special there). A complemented character set can match a newline, unless newline is mentioned as one of the characters not to match. This is in contrast to the handling of regexps in programs such as `grep'. `^' is a special character that matches the empty string, but only at the beginning of a line in the text being matched. Otherwise it fails to match anything. Thus, `^foo' matches a `foo' that occurs at the beginning of a line. `$' is similar to `^' but matches only at the end of a line. Thus, `x+$' matches a string of one `x' or more at the end of a line. `\' has two functions: it quotes the special characters (including `\'), and it introduces additional special constructs. Because `\' quotes special characters, `\$' is a regular expression that matches only `$', and `\[' is a regular expression that matches only `[', and so on. Note: for historical compatibility, special characters are treated as ordinary ones if they are in contexts where their special meanings make no sense. For example, `*foo' treats `*' as ordinary since there is no preceding expression on which the `*' can act. It is poor practice to depend on this behavior; it is better to quote the special character anyway, regardless of where it appears. For the most part, `\' followed by any character matches only that character. However, there are several exceptions: two-character sequences starting with `\' that have special meanings. The second character in the sequence is always an ordinary character when used on its own. Here is a table of `\' constructs. `\|' specifies an alternative. Two regular expressions A and B with `\|' in between form an expression that matches some text if either A matches it or B matches it. It works by trying to match A, and if that fails, by trying to match B. Thus, `foo\|bar' matches either `foo' or `bar' but no other string. `\|' applies to the largest possible surrounding expressions. Only a surrounding `\( ... \)' grouping can limit the grouping power of `\|'. Full backtracking capability exists to handle multiple uses of `\|'. `\( ... \)' is a grouping construct that serves three purposes: 1. To enclose a set of `\|' alternatives for other operations. Thus, `\(foo\|bar\)x' matches either `foox' or `barx'. 2. To enclose a complicated expression for the postfix operators `*', `+' and `?' to operate on. Thus, `ba\(na\)*' matches `bananana', etc., with any (zero or more) number of `na' strings. 3. To record a matched substring for future reference. This last application is not a consequence of the idea of a parenthetical grouping; it is a separate feature that is assigned as a second meaning to the same `\( ... \)' construct. In practice there is no conflict between the two meanings. `\D' matches the same text that matched the Dth occurrence of a `\( ... \)' construct. After the end of a `\( ... \)' construct, the matcher remembers the beginning and end of the text matched by that construct. Then, later on in the regular expression, you can use `\' followed by the digit D to mean "match the same text matched the Dth time by the `\( ... \)' construct." The strings matching the first nine `\( ... \)' constructs appearing in a regular expression are assigned numbers 1 through 9 in the order that the open-parentheses appear in the regular expression. So you can use `\1' through `\9' to refer to the text matched by the corresponding `\( ... \)' constructs. For example, `\(.*\)\1' matches any newline-free string that is composed of two identical halves. The `\(.*\)' matches the first half, which may be anything, but the `\1' that follows must match the same exact text. If a particular `\( ... \)' construct matches more than once (which can easily happen if it is followed by `*'), only the last match is recorded. `\`' matches the empty string, but only at the beginning of the buffer or string being matched against. `\'' matches the empty string, but only at the end of the buffer or string being matched against. `\=' matches the empty string, but only at point. `\b' matches the empty string, but only at the beginning or end of a word. Thus, `\bfoo\b' matches any occurrence of `foo' as a separate word. `\bballs?\b' matches `ball' or `balls' as a separate word. `\b' matches at the beginning or end of the buffer regardless of what text appears next to it. `\B' matches the empty string, but *not* at the beginning or end of a word. `\<' matches the empty string, but only at the beginning of a word. `\<' matches at the beginning of the buffer only if a word-constituent character follows. `\>' matches the empty string, but only at the end of a word. `\>' matches at the end of the buffer only if the contents end with a word-constituent character. `\w' matches any word-constituent character. The syntax table determines which characters these are. *Note Syntax::. `\W' matches any character that is not a word-constituent. `\sC' matches any character whose syntax is C. Here C is a character that represents a syntax code: thus, `w' for word constituent, `-' for whitespace, `(' for open parenthesis, etc. Represent a character of whitespace (which can be a newline) by either `-' or a space character. `\SC' matches any character whose syntax is not C. The constructs that pertain to words and syntax are controlled by the setting of the syntax table (*note Syntax::.). Here is a complicated regexp, used by Emacs to recognize the end of a sentence together with any whitespace that follows. It is given in Lisp syntax to enable you to distinguish the spaces from the tab characters. In Lisp syntax, the string constant begins and ends with a double-quote. `\"' stands for a double-quote as part of the regexp, `\\' for a backslash as part of the regexp, `\t' for a tab and `\n' for a newline. "[.?!][]\"')]*\\($\\|\t\\| \\)[ \t\n]*" This contains four parts in succession: a character set matching period, `?', or `!'; a character set matching close-brackets, quotes, or parentheses, repeated any number of times; an alternative in backslash-parentheses that matches end-of-line, a tab, or two spaces; and a character set matching whitespace characters, repeated any number of times. To enter the same regexp interactively, you would type to enter a tab, and `C-j' to enter a newline. You would also type single backslashes as themselves, instead of doubling them for Lisp syntax.  File: emacs, Node: Search Case, Next: Replace, Prev: Regexps, Up: Search Searching and Case ================== Incremental searches in Emacs normally ignore the case of the text they are searching through, if you specify the text in lower case. Thus, if you specify searching for `foo', then `Foo' and `foo' are also considered a match. Regexps, and in particular character sets, are included: `[ab]' would match `a' or `A' or `b' or `B'. An upper-case letter anywhere in the incremental search string makes the search case-sensitive. Thus, searching for `Foo' does not find `foo' or `FOO'. This applies to regular expression search as well as to string search. The effect ceases if you delete the upper-case letter from the search string. If you set the variable `case-fold-search' to `nil', then all letters must match exactly, including case. This is a per-buffer variable; altering the variable affects only the current buffer, but there is a default value which you can change as well. *Note Locals::. This variable applies to nonincremental searches also, including those performed by the replace commands (*note Replace::.) and the minibuffer history matching commands (*note Minibuffer History::.).  File: emacs, Node: Replace, Next: Other Repeating Search, Prev: Search Case, Up: Search Replacement Commands ==================== Global search-and-replace operations are not needed as often in Emacs as they are in other editors(1), but they are available. In addition to the simple `M-x replace-string' command which is like that found in most editors, there is a `M-x query-replace' command which asks you, for each occurrence of the pattern, whether to replace it. The replace commands normally operate on the text from point to the end of the buffer; however, in Transient Mark mode, when the mark is active, they operate on the region. The replace commands all replace one string (or regexp) with one replacement string. It is possible to perform several replacements in parallel using the command `expand-region-abbrevs' (*note Expanding Abbrevs::.). * Menu: * Unconditional Replace:: Replacing all matches for a string. * Regexp Replace:: Replacing all matches for a regexp. * Replacement and Case:: How replacements preserve case of letters. * Query Replace:: How to use querying. ---------- Footnotes ---------- (1) In some editors, search-and-replace operations are the only convenient way to make a single change in the text.  File: emacs, Node: Unconditional Replace, Next: Regexp Replace, Prev: Replace, Up: Replace Unconditional Replacement ------------------------- `M-x replace-string STRING NEWSTRING ' Replace every occurrence of STRING with NEWSTRING. `M-x replace-regexp REGEXP NEWSTRING ' Replace every match for REGEXP with NEWSTRING. To replace every instance of `foo' after point with `bar', use the command `M-x replace-string' with the two arguments `foo' and `bar'. Replacement happens only in the text after point, so if you want to cover the whole buffer you must go to the beginning first. All occurrences up to the end of the buffer are replaced; to limit replacement to part of the buffer, narrow to that part of the buffer before doing the replacement (*note Narrowing::.). In Transient Mark mode, when the region is active, replacement is limited to the region (*note Transient Mark::.). When `replace-string' exits, it leaves point at the last occurrence replaced. It sets the mark to the prior position of point (where the `replace-string' command was issued); use `C-u C-' to move back there. A numeric argument restricts replacement to matches that are surrounded by word boundaries. The argument's value doesn't matter.  File: emacs, Node: Regexp Replace, Next: Replacement and Case, Prev: Unconditional Replace, Up: Replace Regexp Replacement ------------------ The `M-x replace-string' command replaces exact matches for a single string. The similar command `M-x replace-regexp' replaces any match for a specified pattern. In `replace-regexp', the NEWSTRING need not be constant: it can refer to all or part of what is matched by the REGEXP. `\&' in NEWSTRING stands for the entire match being replaced. `\D' in NEWSTRING, where D is a digit, stands for whatever matched the Dth parenthesized grouping in REGEXP. To include a `\' in the text to replace with, you must enter `\\'. For example, M-x replace-regexp c[ad]+r \&-safe replaces (for example) `cadr' with `cadr-safe' and `cddr' with `cddr-safe'. M-x replace-regexp \(c[ad]+r\)-safe \1 performs the inverse transformation.  File: emacs, Node: Replacement and Case, Next: Query Replace, Prev: Regexp Replace, Up: Replace Replace Commands and Case ------------------------- If the first argument of a replace command is all lower case, the commands ignores case while searching for occurrences to replace--provided `case-fold-search' is non-`nil'. If `case-fold-search' is set to `nil', case is always significant in all searches. In addition, when the NEWSTRING argument is all or partly lower case, replacement commands try to preserve the case pattern of each occurrence. Thus, the command M-x replace-string foo bar replaces a lower case `foo' with a lower case `bar', an all-caps `FOO' with `BAR', and a capitalized `Foo' with `Bar'. (These three alternatives--lower case, all caps, and capitalized, are the only ones that `replace-string' can distinguish.) If upper-case letters are used in the replacement string, they remain upper case every time that text is inserted. If upper-case letters are used in the first argument, the second argument is always substituted exactly as given, with no case conversion. Likewise, if either `case-replace' or `case-fold-search' is set to `nil', replacement is done without case conversion.  File: emacs, Node: Query Replace, Prev: Replacement and Case, Up: Replace Query Replace ------------- `M-% STRING NEWSTRING ' `M-x query-replace STRING NEWSTRING ' Replace some occurrences of STRING with NEWSTRING. `C-M-% REGEXP NEWSTRING ' `M-x query-replace-regexp REGEXP NEWSTRING ' Replace some matches for REGEXP with NEWSTRING. If you want to change only some of the occurrences of `foo' to `bar', not all of them, then you cannot use an ordinary `replace-string'. Instead, use `M-%' (`query-replace'). This command finds occurrences of `foo' one by one, displays each occurrence and asks you whether to replace it. A numeric argument to `query-replace' tells it to consider only occurrences that are bounded by word-delimiter characters. This preserves case, just like `replace-string', provided `case-replace' is non-`nil', as it normally is. Aside from querying, `query-replace' works just like `replace-string', and `query-replace-regexp' works just like `replace-regexp'. This command is run by `C-M-%'. The things you can type when you are shown an occurrence of STRING or a match for REGEXP are: `' to replace the occurrence with NEWSTRING. `' to skip to the next occurrence without replacing this one. `, (Comma)' to replace this occurrence and display the result. You are then asked for another input character to say what to do next. Since the replacement has already been made, and are equivalent in this situation; both move to the next occurrence. You can type `C-r' at this point (see below) to alter the replaced text. You can also type `C-x u' to undo the replacement; this exits the `query-replace', so if you want to do further replacement you must use `C-x ' to restart (*note Repetition::.). `' to exit without doing any more replacements. `. (Period)' to replace this occurrence and then exit without searching for more occurrences. `!' to replace all remaining occurrences without asking again. `^' to go back to the position of the previous occurrence (or what used to be an occurrence), in case you changed it by mistake. This works by popping the mark ring. Only one `^' in a row is meaningful, because only one previous replacement position is kept during `query-replace'. `C-r' to enter a recursive editing level, in case the occurrence needs to be edited rather than just replaced with NEWSTRING. When you are done, exit the recursive editing level with `C-M-c' to proceed to the next occurrence. *Note Recursive Edit::. `C-w' to delete the occurrence, and then enter a recursive editing level as in `C-r'. Use the recursive edit to insert text to replace the deleted occurrence of STRING. When done, exit the recursive editing level with `C-M-c' to proceed to the next occurrence. `C-l' to redisplay the screen. Then you must type another character to specify what to do with this occurrence. `C-h' to display a message summarizing these options. Then you must type another character to specify what to do with this occurrence. Some other characters are aliases for the ones listed above: `y', `n' and `q' are equivalent to , and . Aside from this, any other character exits the `query-replace', and is then reread as part of a key sequence. Thus, if you type `C-k', it exits the `query-replace' and then kills to end of line. To restart a `query-replace' once it is exited, use `C-x ', which repeats the `query-replace' because it used the minibuffer to read its arguments. *Note C-x ESC ESC: Repetition. See also *Note Transforming File Names::, for Dired commands to rename, copy, or link files by replacing regexp matches in file names.  File: emacs, Node: Other Repeating Search, Prev: Replace, Up: Search Other Search-and-Loop Commands ============================== Here are some other commands that find matches for a regular expression. They all operate from point to the end of the buffer, and all ignore case in matching, if the pattern contains no upper-case letters and `case-fold-search' is non-`nil'. `M-x occur REGEXP ' Display a list showing each line in the buffer that contains a match for REGEXP. A numeric argument specifies the number of context lines to print before and after each matching line; the default is none. To limit the search to part of the buffer, narrow to that part (*note Narrowing::.). The buffer `*Occur*' containing the output serves as a menu for finding the occurrences in their original context. Click `Mouse-2' on an occurrence listed in `*Occur*', or position point there and type ; this switches to the buffer that was searched and moves point to the original of the chosen occurrence. `M-x list-matching-lines' Synonym for `M-x occur'. `M-x count-matches REGEXP ' Print the number of matches for REGEXP after point. `M-x flush-lines REGEXP ' Delete each line that follows point and contains a match for REGEXP. `M-x keep-lines REGEXP ' Delete each line that follows point and *does not* contain a match for REGEXP. In addition, you can use `grep' from Emacs to search a collection of files for matches for a regular expression, then visit the matches either sequentially or in arbitrary order. *Note Grep Searching::.  File: emacs, Node: Fixit, Next: Files, Prev: Search, Up: Top Commands for Fixing Typos ************************* In this chapter we describe the commands that are especially useful for the times when you catch a mistake in your text just after you have made it, or change your mind while composing text on the fly. The most fundamental command for correcting erroneous editing is the undo command, `C-x u' or `C-_'. This command undoes a single command (usually), a part of a command (in the case of `query-replace'), or several consecutive self-inserting characters. Consecutive repetitions of `C-_' or `C-x u' undo earlier and earlier changes, back to the limit of the undo information available. *Note Undo::, for for more information. * Menu: * Kill Errors:: Commands to kill a batch of recently entered text. * Transpose:: Exchanging two characters, words, lines, lists... * Fixing Case:: Correcting case of last word entered. * Spelling:: Apply spelling checker to a word, or a whole file.  File: emacs, Node: Kill Errors, Next: Transpose, Up: Fixit Killing Your Mistakes ===================== `' Delete last character (`delete-backward-char'). `M-' Kill last word (`backward-kill-word'). `C-x ' Kill to beginning of sentence (`backward-kill-sentence'). The character (`delete-backward-char') is the most important correction command. It deletes the character before point. When follows a self-inserting character command, you can think of it as canceling that command. However, avoid the mistake of thinking of as a general way to cancel a command! When your mistake is longer than a couple of characters, it might be more convenient to use `M-' or `C-x '. `M-' kills back to the start of the last word, and `C-x ' kills back to the start of the last sentence. `C-x ' is particularly useful when you change your mind about the phrasing of the text you are writing. `M-' and `C-x ' save the killed text for `C-y' and `M-y' to retrieve. *Note Yanking::. `M-' is often useful even when you have typed only a few characters wrong, if you know you are confused in your typing and aren't sure exactly what you typed. At such a time, you cannot correct with except by looking at the screen to see what you did. Often it requires less thought to kill the whole word and start again.  File: emacs, Node: Transpose, Next: Fixing Case, Prev: Kill Errors, Up: Fixit Transposing Text ================ `C-t' Transpose two characters (`transpose-chars'). `M-t' Transpose two words (`transpose-words'). `C-M-t' Transpose two balanced expressions (`transpose-sexps'). `C-x C-t' Transpose two lines (`transpose-lines'). The common error of transposing two characters can be fixed, when they are adjacent, with the `C-t' command (`transpose-chars'). Normally, `C-t' transposes the two characters on either side of point. When given at the end of a line, rather than transposing the last character of the line with the newline, which would be useless, `C-t' transposes the last two characters on the line. So, if you catch your transposition error right away, you can fix it with just a `C-t'. If you don't catch it so fast, you must move the cursor back to between the two transposed characters. If you transposed a space with the last character of the word before it, the word motion commands are a good way of getting there. Otherwise, a reverse search (`C-r') is often the best way. *Note Search::. `M-t' (`transpose-words') transposes the word before point with the word after point. It moves point forward over a word, dragging the word preceding or containing point forward as well. The punctuation characters between the words do not move. For example, `FOO, BAR' transposes into `BAR, FOO' rather than `BAR FOO,'. `C-M-t' (`transpose-sexps') is a similar command for transposing two expressions (*note Lists::.), and `C-x C-t' (`transpose-lines') exchanges lines. They work like `M-t' except in determining the division of the text into syntactic units. A numeric argument to a transpose command serves as a repeat count: it tells the transpose command to move the character (word, sexp, line) before or containing point across several other characters (words, sexps, lines). For example, `C-u 3 C-t' moves the character before point forward across three other characters. It would change `f-!-oobar' into `oobf-!-ar'. This is equivalent to repeating `C-t' three times. `C-u - 4 M-t' moves the word before point backward across four words. `C-u - C-M-t' would cancel the effect of plain `C-M-t'. A numeric argument of zero is assigned a special meaning (because otherwise a command with a repeat count of zero would do nothing): to transpose the character (word, sexp, line) ending after point with the one ending after the mark.  File: emacs, Node: Fixing Case, Next: Spelling, Prev: Transpose, Up: Fixit Case Conversion =============== `M-- M-l' Convert last word to lower case. Note `Meta--' is Meta-minus. `M-- M-u' Convert last word to all upper case. `M-- M-c' Convert last word to lower case with capital initial. A very common error is to type words in the wrong case. Because of this, the word case-conversion commands `M-l', `M-u' and `M-c' have a special feature when used with a negative argument: they do not move the cursor. As soon as you see you have mistyped the last word, you can simply case-convert it and go on typing. *Note Case::.  File: emacs, Node: Spelling, Prev: Fixing Case, Up: Fixit Checking and Correcting Spelling ================================ This section describes the commands to check the spelling of a single word or of a portion of a buffer. These commands work with the spelling checker program Ispell, which is not part of Emacs. *Note Ispell: (ispell.info)Top. `M-x flyspell-mode' Enable Flyspell mode, which highlights all misspelled words. `M-$' Check and correct spelling of the word at point (`ispell-word'). `M-' Complete the word before point based on the spelling dictionary (`ispell-complete-word'). `M-x ispell-buffer' Check and correct spelling of each word in the buffer. `M-x ispell-region' Check and correct spelling of each word in the region. `M-x ispell-message' Check and correct spelling of each word in a draft mail message, excluding cited material. `M-x ispell-change-dictionary DICT ' Restart the Ispell process, using DICT as the dictionary. `M-x ispell-kill-ispell' Kill the Ispell subprocess. Flyspell mode is a fully-automatic way to check spelling as you edit in Emacs. It operates by checking words as you change or insert them. When it finds a word that it does not recognize, it highlights that word. This does not interfere with your editing, but when you see the highlighted word, you can move to it and fix it. Type `M-x flyspell-mode' to enable or disable this mode in the current buffer. When Flyspell mode highlights a word as misspelled, you can click on it with `Mouse-2' to display a menu of possible corrections and actions. You can also correct the word by editing it manually in any way you like. The other Emacs spell-checking features check or look up words when you give an explicit command to do so. Checking all or part of the buffer is useful when you have text that was written outside of this Emacs session and might contain any number of misspellings. To check the spelling of the word around or next to point, and optionally correct it as well, use the command `M-$' (`ispell-word'). If the word is not correct, the command offers you various alternatives for what to do about it. To check the entire current buffer, use `M-x ispell-buffer'. Use `M-x ispell-region' to check just the current region. To check spelling in an email message you are writing, use `M-x ispell-message'; that checks the whole buffer, but does not check material that is indented or appears to be cited from other messages. Each time these commands encounter an incorrect word, they ask you what to do. They display a list of alternatives, usually including several "near-misses"--words that are close to the word being checked. Then you must type a character. Here are the valid responses: `' Skip this word--continue to consider it incorrect, but don't change it here. `r NEW ' Replace the word (just this time) with NEW. `R NEW ' Replace the word with NEW, and do a `query-replace' so you can replace it elsewhere in the buffer if you wish. `DIGIT' Replace the word (just this time) with one of the displayed near-misses. Each near-miss is listed with a digit; type that digit to select it. `a' Accept the incorrect word--treat it as correct, but only in this editing session. `A' Accept the incorrect word--treat it as correct, but only in this editing session and for this buffer. `i' Insert this word in your private dictionary file so that Ispell will consider it correct it from now on, even in future sessions. `u' Insert the lower-case version of this word in your private dictionary file. `m' Like `i', but you can also specify dictionary completion information. `l WORD ' Look in the dictionary for words that match WORD. These words become the new list of "near-misses"; you can select one of them to replace with by typing a digit. You can use `*' in WORD as a wildcard. `C-g' Quit interactive spell checking. You can restart it again afterward with `C-u M-$'. `X' Same as `C-g'. `x' Quit interactive spell checking and move point back to where it was when you started spell checking. `q' Quit interactive spell checking and kill the Ispell subprocess. `C-l' Refresh the screen. `C-z' This key has its normal command meaning (suspend Emacs or iconify this frame). The command `ispell-complete-word', which is bound to the key `M-' in Text mode and related modes, shows a list of completions based on spelling correction. Insert the beginning of a word, and then type `M-'; the command displays a completion list window. To choose one of the completions listed, click `Mouse-2' on it, or move the cursor there in the completions window and type . *Note Text Mode::. Once started, the Ispell subprocess continues to run (waiting for something to do), so that subsequent spell checking commands complete more quickly. If you want to get rid of the Ispell process, use `M-x ispell-kill-ispell'. This is not usually necessary, since the process uses no time except when you do spelling correction. Ispell uses two dictionaries: the standard dictionary and your private dictionary. The variable `ispell-dictionary' specifies the file name of the standard dictionary to use. A value of `nil' says to use the default dictionary. The command `M-x ispell-change-dictionary' sets this variable and then restarts the Ispell subprocess, so that it will use a different dictionary.