@c This is part of the Emacs manual.
-@c Copyright (C) 1985, 86, 87, 93, 94, 95, 97, 2000
-@c Free Software Foundation, Inc.
+@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001, 2002,
+@c 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Search, Fixit, Display, Top
@chapter Searching and Replacement
those of other editors.
Besides the usual @code{replace-string} command that finds all
-occurrences of one string and replaces them with another, Emacs has a fancy
-replacement command called @code{query-replace} which asks interactively
-which occurrences to replace.
+occurrences of one string and replaces them with another, Emacs has a
+more flexible replacement command called @code{query-replace}, which
+asks interactively which occurrences to replace.
@menu
-* Incremental Search:: Search happens as you type the string.
-* Nonincremental Search:: Specify entire string and then search.
-* Word Search:: Search for sequence of words.
-* Regexp Search:: Search for match for a regexp.
-* Regexps:: Syntax of regular expressions.
-* Search Case:: To ignore case while searching, or not.
-* Replace:: Search, and replace some or all matches.
-* Other Repeating Search:: Operating on all matches for some regexp.
+* Incremental Search:: Search happens as you type the string.
+* Nonincremental Search:: Specify entire string and then search.
+* Word Search:: Search for sequence of words.
+* Regexp Search:: Search for match for a regexp.
+* Regexps:: Syntax of regular expressions.
+* Regexp Backslash:: Regular expression constructs starting with `\'.
+* Regexp Example:: A complex regular expression explained.
+* Search Case:: To ignore case while searching, or not.
+* Replace:: Search, and replace some or all matches.
+* Other Repeating Search:: Operating on all matches for some regexp.
@end menu
-@node Incremental Search, Nonincremental Search, Search, Search
+@node Incremental Search
@section Incremental Search
-@cindex 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
want, you can stop. Depending on what you plan to do next, you may or
may not need to terminate the search explicitly with @key{RET}.
-@c WideCommands
@table @kbd
@item C-s
Incremental search forward (@code{isearch-forward}).
Incremental search backward (@code{isearch-backward}).
@end table
+@menu
+* Basic Isearch:: Basic incremental search commands.
+* Repeat Isearch:: Searching for the same string again.
+* Error in Isearch:: When your string is not found.
+* Special Isearch:: Special input in incremental search.
+* Non-ASCII Isearch:: How to search for non-ASCII characters.
+* Isearch Yank:: Commands that grab text into the search string
+ or else edit the search string.
+* Highlight Isearch:: Isearch highlights the other possible matches.
+* Isearch Scroll:: Scrolling during an incremental search.
+* Slow Isearch:: Incremental search features for slow terminals.
+@end menu
+
+@node Basic Isearch
+@subsection Basics of Incremental Search
+@cindex incremental search
+
@kindex C-s
@findex isearch-forward
- @kbd{C-s} starts an incremental search. @kbd{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 @kbd{C-s} and then @kbd{F},
-the cursor moves right after the first @samp{F}. Type an @kbd{O}, and see
-the cursor move to after the first @samp{FO}. After another @kbd{O}, the
-cursor is after the first @samp{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. Multilingual text can be input by
-toggling input methods with @kbd{C-\} or @kbd{C-^}, see below.
+ @kbd{C-s} starts a forward incremental search. It reads characters
+from the keyboard, and moves point past the next occurrence of those
+characters. If you type @kbd{C-s} and then @kbd{F}, that puts the
+cursor after the first @samp{F} (the first following the starting point, since
+this is a forward search). Then if you type an @kbd{O}, you will see
+the cursor move to just after the first @samp{FO} (the @samp{F} in that
+@samp{FO} may or may not be the first @samp{F}). After another
+@kbd{O}, the cursor moves to just after the first @samp{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;
+the current search string is always displayed in the echo area.
If you make a mistake in typing the search string, you can cancel
characters with @key{DEL}. Each @key{DEL} cancels the last character of
When you are satisfied with the place you have reached, you can type
@key{RET}, 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 @kbd{C-a} would
-exit the search and then move to the beginning of the line. @key{RET}
-is necessary only if the next command you want to type is a printing
-character, @key{DEL}, @key{RET}, or another control character that is
+stops the searching and is then executed. Thus, typing @kbd{C-a}
+would exit the search and then move to the beginning of the line.
+@key{RET} is necessary only if the next command you want to type is a
+printing character, @key{DEL}, @key{RET}, or another character that is
special within searches (@kbd{C-q}, @kbd{C-w}, @kbd{C-r}, @kbd{C-s},
-@kbd{C-y}, @kbd{M-y}, @kbd{M-r}, or @kbd{M-s}).
+@kbd{C-y}, @kbd{M-y}, @kbd{M-r}, @kbd{M-c}, @kbd{M-e}, and some other
+meta-characters).
+
+ When you exit the incremental search, it sets the mark where point
+@emph{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.
+
+@node Repeat Isearch
+@subsection Repeating Incremental Search
- Sometimes you search for @samp{FOO} and find it, but not the one you
-expected to find. There was a second @samp{FOO} that you forgot about,
-before the one you were aiming for. In this event, type another @kbd{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 @kbd{C-s}
-characters with @key{DEL}.
+ Sometimes you search for @samp{FOO} and find one, but not the one you
+expected to find. There was a second @samp{FOO} that you forgot
+about, before the one you were aiming for. In this event, type
+another @kbd{C-s} to move to the next occurrence of the search string.
+You can repeat this any number of times. If you overshoot, you can
+cancel some @kbd{C-s} characters with @key{DEL}.
After you exit a search, you can search for the same string again by
typing just @kbd{C-s C-s}: the first @kbd{C-s} is the key that invokes
incremental search, and the second @kbd{C-s} means ``search again.''
+ If a search is failing and you ask to repeat it by typing another
+@kbd{C-s}, it starts again from the beginning of the buffer.
+Repeating a failing reverse search with @kbd{C-r} starts again from
+the end. This is called @dfn{wrapping around}, and @samp{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
+@samp{Overwrapped}, which means that you are revisiting matches that
+you have already seen.
+
To reuse earlier search strings, use the @dfn{search ring}. The
commands @kbd{M-p} and @kbd{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 @kbd{C-s} or @kbd{C-r}
+in the minibuffer, where you can edit it. To edit the current search
+string in the minibuffer without replacing it with items from the
+search ring, type @kbd{M-e}. Type @kbd{C-s} or @kbd{C-r}
to terminate editing the string and search for it.
+ You can change to searching backwards with @kbd{C-r}. For instance,
+if you are searching forward but you realize you were looking for
+something above the starting point, you can do this. Repeated
+@kbd{C-r} keeps looking for more occurrences backwards. A @kbd{C-s}
+starts going forwards again. @kbd{C-r} in a search can be canceled
+with @key{DEL}.
+
+@kindex C-r
+@findex isearch-backward
+ If you know initially that you want to search backwards, you can use
+@kbd{C-r} instead of @kbd{C-s} to start the search, because @kbd{C-r}
+as a key runs a command (@code{isearch-backward}) to search backward.
+A backward search finds matches that end before the starting point,
+just as a forward search finds matches that begin after it.
+
+@node Error in Isearch
+@subsection Errors in Incremental Search
+
If your string is not found at all, the echo area says @samp{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 @samp{FOOT}, and there is no
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 @key{RET} or some other Emacs command to
-``accept what the search offered.'' Or you can type @kbd{C-g}, which
+remain there. Or you can type @kbd{C-g}, which
removes from the search string the characters that could not be found (the
@samp{T} in @samp{FOOT}), leaving those that were found (the @samp{FOO} in
@samp{FOOT}). A second @kbd{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. @xref{Search Case}.
-
-@cindex searching for non-ASCII characters
-@cindex input method, during incremental search
- If an input method (@pxref{Input Methods}) is turned on in the
-current buffer when you start the search, that input method is used to
-read the characters while you type the search string. Emacs indicates
-that by including the input method mnemonic in its prompt, like this:
-
-@example
- I-search [@var{im}]:
-@end example
-
-@noindent
-@findex isearch-toggle-input-method
-@findex isearch-toggle-specified-input-method
-where @var{im} is the mnemonic of the active input method. You can
-toggle (enable or disable) the input method while you type the search
-string with @kbd{C-\} (@code{isearch-toggle-input-method}). You can
-turn on a certain (non-default) input method with @kbd{C-^}
-(@code{isearch-toggle-specified-input-method}), which prompts for the
-name of the input method. Note that the input method you turn on
-during incremental search is turned on in the current buffer as well.
-
- If a search is failing and you ask to repeat it by typing another
-@kbd{C-s}, it starts again from the beginning of the buffer. Repeating
-a failing reverse search with @kbd{C-r} starts again from the end. This
-is called @dfn{wrapping around}. @samp{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 @samp{Overwrapped}, which
-means that you are revisiting matches that you have already seen.
-
@cindex quitting (in search)
The @kbd{C-g} ``quit'' character does special things during searches;
just what it does depends on the status of the search. If the search has
search is now successful and waiting for more input, so a second @kbd{C-g}
will cancel the entire search.
+@node Special Isearch
+@subsection Special Input for Incremental Search
+
+ 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. @xref{Search Case}.
+
To search for a newline, type @kbd{C-j}. To search for another
control character, such as control-S or carriage return, you must quote
it by typing @kbd{C-q} first. This function of @kbd{C-q} is analogous
treated in the same context. You can also specify a character by its
octal code: enter @kbd{C-q} followed by a sequence of octal digits.
- You can change to searching backwards with @kbd{C-r}. If a search fails
-because the place you started was too late in the file, you should do this.
-Repeated @kbd{C-r} keeps looking for more occurrences backwards. A
-@kbd{C-s} starts going forwards again. @kbd{C-r} in a search can be canceled
-with @key{DEL}.
+ @kbd{M-%} typed in incremental search invokes @code{query-replace}
+or @code{query-replace-regexp} (depending on search mode) with the
+current search string used as the string to replace. @xref{Query
+Replace}.
-@kindex C-r
-@findex isearch-backward
- If you know initially that you want to search backwards, you can use
-@kbd{C-r} instead of @kbd{C-s} to start the search, because @kbd{C-r} as
-a key runs a command (@code{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 @kbd{C-y} and @kbd{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.
-@kbd{C-w} copies the word after point as part of the search string,
-advancing point over that word. Another @kbd{C-s} to repeat the search
-will then search for a string including that word. @kbd{C-y} is similar
-to @kbd{C-w} but copies all the rest of the current line into the search
-string. Both @kbd{C-y} and @kbd{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.
+ Entering @key{RET} when the search string is empty launches
+nonincremental search (@pxref{Nonincremental Search}).
+
+@vindex isearch-mode-map
+ To customize the special characters that incremental search understands,
+alter their bindings in the keymap @code{isearch-mode-map}. For a list
+of bindings, look at the documentation of @code{isearch-mode} with
+@kbd{C-h f isearch-mode @key{RET}}.
+
+@node Non-ASCII Isearch
+@subsection Isearch for Non-@acronym{ASCII} Characters
+
+@cindex searching for non-@acronym{ASCII} characters
+@cindex input method, during incremental search
+
+ To enter non-@acronym{ASCII} characters in an incremental search,
+you must use an input method (@pxref{Input Methods}). If an input
+method is enabled in the current buffer when you start the search, you
+can use it while you type the search string also. Emacs indicates
+that by including the input method mnemonic in its prompt, like this:
+
+@example
+I-search [@var{im}]:
+@end example
+
+@noindent
+@findex isearch-toggle-input-method
+@findex isearch-toggle-specified-input-method
+where @var{im} is the mnemonic of the active input method. You can
+toggle (enable or disable) the input method while you type the search
+string with @kbd{C-\} (@code{isearch-toggle-input-method}). You can
+turn on a certain (non-default) input method with @kbd{C-^}
+(@code{isearch-toggle-specified-input-method}), which prompts for the
+name of the input method. The input method you enable during
+incremental search remains enabled in the current buffer afterwards.
+
+@node Isearch Yank
+@subsection Isearch Yanking
+
+ The characters @kbd{C-w} and @kbd{C-y} 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.
+@kbd{C-w} copies the character or word after point as part of the
+search string, advancing point over it. (The decision, whether to
+copy a character or a word, is heuristic.) Another @kbd{C-s} to
+repeat the search will then search for a string including that
+character or word.
+
+ @kbd{C-y} is similar to @kbd{C-w} but copies all the rest of the
+current line into the search string. If point is already at the end
+of a line, it grabs the entire next line. Both @kbd{C-y} and
+@kbd{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.
+
+ @kbd{C-M-w} and @kbd{C-M-y} modify the search string by only one
+character at a time: @kbd{C-M-w} deletes the last character from the
+search string and @kbd{C-M-y} copies the character after point to the
+end of the search string. An alternative method to add the character
+after point into the search string is to enter the minibuffer by
+@kbd{M-e} and to type @kbd{C-f} at the end of the search string in the
+minibuffer.
The character @kbd{M-y} copies text from the kill ring into the search
string. It uses the same text that @kbd{C-y} as a command would yank.
-@kbd{mouse-2} in the echo area does the same.
+@kbd{Mouse-2} in the echo area does the same.
@xref{Yanking}.
- When you exit the incremental search, it sets the mark to where point
-@emph{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.
-
+@node Highlight Isearch
+@subsection Lazy Search Highlighting
@cindex lazy search highlighting
- By default, Isearch uses @dfn{lazy highlighting}. All matches for
-the current search string in the buffer after the point where searching
-starts are highlighted. The extra highlighting makes it easier to
-anticipate where the cursor will end up each time you press @kbd{C-s} or
-@kbd{C-r} to repeat a pending search. Highlighting of these additional
-matches happens in a deferred fashion so as not to rob Isearch of its
-usual snappy response.
-@vindex isearch-lazy-highlight-cleanup
-@findex isearch-lazy-highlight-cleanup
-By default the highlighting of matches is cleared when you end the
-search. Customize the variable @code{isearch-lazy-highlight-cleanup} to
-avoid cleaning up automatically. The command @kbd{M-x
-isearch-lazy-highlight-cleanup} can be used to clean up manually.
@vindex isearch-lazy-highlight
-Customize the variable @code{isearch-lazy-highlight} to turn off this
-feature.
-@vindex isearch-lazy-highlight-face
+ When you pause for a little while during incremental search, it
+highlights all other possible matches for the search string. This
+makes it easier to anticipate where you can get to by typing @kbd{C-s}
+or @kbd{C-r} to repeat the search. The short delay before highlighting
+other matches helps indicate which match is the current one.
+If you don't like this feature, you can turn it off by setting
+@code{isearch-lazy-highlight} to @code{nil}.
+
@cindex faces for highlighting search matches
- You can control how does the highlighting of matches look like by
-customizing the faces @code{isearch} (highlights the current match) and
-@code{isearch-lazy-highlight-face} (highlights the other matches).
+ You can control how this highlighting looks by customizing the faces
+@code{isearch} (used for the current match) and @code{lazy-highlight}
+(for all the other matches).
+
+@node Isearch Scroll
+@subsection Scrolling During Incremental Search
+
+ You can enable the use of vertical scrolling during incremental
+search (without exiting the search) by setting the customizable
+variable @code{isearch-allow-scroll} to a non-@code{nil} value. This
+applies to using the vertical scroll-bar and to certain keyboard
+commands such as @kbd{@key{PRIOR}} (@code{scroll-down}),
+@kbd{@key{NEXT}} (@code{scroll-up}) and @kbd{C-l} (@code{recenter}).
+You must run these commands via their key sequences to stay in the
+search---typing @kbd{M-x} will terminate the search. You can give
+prefix arguments to these commands in the usual way.
+
+ This feature won't let you scroll the current match out of visibility,
+however.
+
+ The feature also affects some other commands, such as @kbd{C-x 2}
+(@code{split-window-vertically}) and @kbd{C-x ^}
+(@code{enlarge-window}) which don't exactly scroll but do affect where
+the text appears on the screen. In general, it applies to any command
+whose name has a non-@code{nil} @code{isearch-scroll} property. So you
+can control which commands are affected by changing these properties.
+
+ For example, to make @kbd{C-h l} usable within an incremental search
+in all future Emacs sessions, use @kbd{C-h c} to find what command it
+runs. (You type @kbd{C-h c C-h l}; it says @code{view-lossage}.)
+Then you can put the following line in your @file{.emacs} file
+(@pxref{Init File}):
-@vindex isearch-mode-map
- To customize the special characters that incremental search understands,
-alter their bindings in the keymap @code{isearch-mode-map}. For a list
-of bindings, look at the documentation of @code{isearch-mode} with
-@kbd{C-h f isearch-mode @key{RET}}.
+@example
+(put 'view-lossage 'isearch-scroll t)
+@end example
+
+@noindent
+This feature can be applied to any command that doesn't permanently
+change point, the buffer contents, the match data, the current buffer,
+or the selected window and frame. The command must not itself attempt
+an incremental search.
+@node Slow Isearch
@subsection 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
+comes into play as soon as point moves 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
+Emacs then redisplays the window in which the search was done, to show
its new position of point.
-@ignore
- The three dots at the end of the search string, normally used to indicate
-that searching is going on, are not displayed in slow style display.
-@end ignore
-
@vindex search-slow-speed
The slow terminal style of display is used when the terminal baud rate is
less than or equal to the value of the variable @code{search-slow-speed},
-initially 1200.
+initially 1200. See also the discussion of the variable @code{baud-rate}
+(@pxref{baud-rate,, Customization of Display}).
@vindex search-slow-window-lines
The number of lines to use in slow terminal search display is controlled
by the variable @code{search-slow-window-lines}. Its normal value is 1.
-@node Nonincremental Search, Word Search, Incremental Search, Search
+@node Nonincremental Search
@section Nonincremental Search
@cindex nonincremental search
To do a nonincremental search, first type @kbd{C-s @key{RET}}. This
enters the minibuffer to read the search string; terminate the string
with @key{RET}, and then the search takes place. If the string is not
-found, the search command gets an error.
-
- The way @kbd{C-s @key{RET}} works is that the @kbd{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.) @kbd{C-r @key{RET}} also works this way.
-
- However, nonincremental searches performed using @kbd{C-s @key{RET}} do
-not call @code{search-forward} right away. The first thing done is to see
-if the next character is @kbd{C-w}, which requests a word search.
+found, the search command signals an error.
+
+ When you type @kbd{C-s @key{RET}}, the @kbd{C-s} invokes incremental
+search as usual. That command is specially programmed to invoke
+nonincremental search, @code{search-forward}, if the string you
+specify is empty. (Such an empty argument would otherwise be
+useless.) But it does not call @code{search-forward} right away. First
+it checks the next input character to see if is @kbd{C-w},
+which specifies a word search.
@ifinfo
@xref{Word Search}.
@end ifinfo
+@kbd{C-r @key{RET}} does likewise, for a reverse incremental search.
@findex search-forward
@findex search-backward
commands @code{search-forward} and @code{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
+historical reasons, and to avoid the need to find separate key sequences
for them.
-@node Word Search, Regexp Search, Nonincremental Search, Search
+@node Word Search
@section Word Search
@cindex 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.
+using single spaces to separate them, and the string can be found even
+if there are multiple spaces, newlines, or other punctuation characters
+between these 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,
@findex word-search-backward
Forward and backward word searches are implemented by the commands
@code{word-search-forward} and @code{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.
+commands may be bound to keys in the usual manner. They are available
+via the incremental search commands both for historical reasons and
+to avoid the need to find separate key sequences for them.
-@node Regexp Search, Regexps, Word Search, Search
+@node Regexp Search
@section Regular Expression Search
@cindex regular expression
@cindex regexp
- A @dfn{regular expression} (@dfn{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.
+ A @dfn{regular expression} (@dfn{regexp}, for short) is a pattern
+that denotes a class of alternative strings to match, possibly
+infinitely many. GNU Emacs provides both incremental and
+nonincremental ways to search for a match for a regexp. The syntax of
+regular expressions is explained in the following section.
@kindex C-M-s
@findex isearch-forward-regexp
@kindex C-M-r
@findex isearch-backward-regexp
Incremental search for a regexp is done by typing @kbd{C-M-s}
-(@code{isearch-forward-regexp}). This command reads a search string
-incrementally just like @kbd{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 @kbd{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 @kbd{C-M-r} (@code{isearch-backward-regexp}), or @kbd{C-r} with a
-prefix argument.
+(@code{isearch-forward-regexp}), by invoking @kbd{C-s} with a
+prefix argument (whose value does not matter), or by typing @kbd{M-r}
+within a forward incremental search. This command reads a
+search string incrementally just like @kbd{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. To search backward for a regexp, use @kbd{C-M-r}
+(@code{isearch-backward-regexp}), @kbd{C-r} with a prefix argument,
+or @kbd{M-r} within a backward incremental search.
All of the control characters that do special things within an
ordinary incremental search have the same function in incremental regexp
defaults. They also have separate search rings that you can access with
@kbd{M-p} and @kbd{M-n}.
+@vindex search-whitespace-regexp
If you type @key{SPC} in incremental regexp search, it matches any
-sequence of whitespace characters, including newlines. If you want
-to match just a space, type @kbd{C-q @key{SPC}}.
+sequence of whitespace characters, including newlines. If you want to
+match just a space, type @kbd{C-q @key{SPC}}. You can control what a
+bare space matches by setting the variable
+@code{search-whitespace-regexp} to the desired regexp.
- Note that adding characters to the regexp in an incremental regexp
+ In some cases, 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 @samp{foo} and you add @samp{\|bar}, the cursor
backs up in case the first @samp{bar} precedes the first @samp{foo}.
@code{isearch-forward} and @code{isearch-backward}. @xref{Incremental
Search}.
-@node Regexps, Search Case, Regexp Search, Search
+@node Regexps
@section Syntax of Regular Expressions
-@cindex regexp syntax
+@cindex syntax of regexps
+
+ This manual describes regular expression features that users
+typically want to use. There are additional features that are
+mainly used in Lisp programs; see @ref{Regular Expressions,,,
+elisp, The Emacs Lisp Reference Manual}.
Regular expressions have a syntax in which a few characters are
special constructs and the rest are @dfn{ordinary}. An ordinary
character is a simple regular expression which matches that same
character and nothing else. The special characters are @samp{$},
-@samp{^}, @samp{.}, @samp{*}, @samp{+}, @samp{?}, @samp{[}, @samp{]} and
-@samp{\}. Any other character appearing in a regular expression is
-ordinary, unless a @samp{\} precedes it.
+@samp{^}, @samp{.}, @samp{*}, @samp{+}, @samp{?}, @samp{[}, and
+@samp{\}. The character @samp{]} is special if it ends a character
+alternative (see later). The character @samp{-} is special inside a
+character alternative. Any other character appearing in a regular
+expression is ordinary, unless a @samp{\} precedes it. (When you use
+regular expressions in a Lisp program, each @samp{\} must be doubled,
+see the example near the end of this section.)
For example, @samp{f} is not a special character, so it is ordinary, and
therefore @samp{f} is a regular expression that matches the string
the string @samp{fo}. Still trivial. To do something nontrivial, you
need to use one of the special characters. Here is a list of them.
-@table @kbd
-@item .@: @r{(Period)}
+@table @asis
+@item @kbd{.}@: @r{(Period)}
is a special character that matches any single character except a newline.
Using concatenation, we can make regular expressions like @samp{a.b}, which
matches any three-character string that begins with @samp{a} and ends with
@samp{b}.@refill
-@item *
+@item @kbd{*}
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, @samp{o*} matches any number of @samp{o}s (including no
The next alternative is for @samp{a*} to match only two @samp{a}s.
With this choice, the rest of the regexp matches successfully.@refill
-@item +
+@item @kbd{+}
is a postfix operator, similar to @samp{*} except that it must match
the preceding expression at least once. So, for example, @samp{ca+r}
matches the strings @samp{car} and @samp{caaaar} but not the string
@samp{cr}, whereas @samp{ca*r} matches all three strings.
-@item ?
+@item @kbd{?}
is a postfix operator, similar to @samp{*} except that it can match the
preceding expression either once or not at all. For example,
@samp{ca?r} matches @samp{car} or @samp{cr}; nothing else.
-@item *?, +?, ??
+@item @kbd{*?}, @kbd{+?}, @kbd{??}
@cindex non-greedy regexp matching
are non-greedy variants of the operators above. The normal operators
-@samp{*}, @samp{+}, @samp{?} are @dfn{greedy} in that they match as much
-as they can, while if you append a @samp{?} after them, it makes them
-non-greedy: they will match as little as possible.
-
-@item \@{@var{n},@var{m}\@}
-is another postfix operator that specifies an interval of iteration:
-the preceding regular expression must match between @var{n} and
-@var{m} times. If @var{m} is omitted, then there is no upper bound
-and if @samp{,@var{m}} is omitted, then the regular expression must match
-exactly @var{n} times. @*
-@samp{\@{0,1\@}} is equivalent to @samp{?}. @*
-@samp{\@{0,\@}} is equivalent to @samp{*}. @*
-@samp{\@{1,\@}} is equivalent to @samp{+}. @*
-@samp{\@{@var{n}\@}} is equivalent to @samp{\@{@var{n},@var{n}\@}}.
-
-@item [ @dots{} ]
+@samp{*}, @samp{+}, @samp{?} are @dfn{greedy} in that they match as
+much as they can, as long as the overall regexp can still match. With
+a following @samp{?}, they are non-greedy: they will match as little
+as possible.
+
+Thus, both @samp{ab*} and @samp{ab*?} can match the string @samp{a}
+and the string @samp{abbbb}; but if you try to match them both against
+the text @samp{abbb}, @samp{ab*} will match it all (the longest valid
+match), while @samp{ab*?} will match just @samp{a} (the shortest
+valid match).
+
+Non-greedy operators match the shortest possible string starting at a
+given starting point; in a forward search, though, the earliest
+possible starting point for match is always the one chosen. Thus, if
+you search for @samp{a.*?$} against the text @samp{abbab} followed by
+a newline, it matches the whole string. Since it @emph{can} match
+starting at the first @samp{a}, it does.
+
+@item @kbd{\@{@var{n}\@}}
+is a postfix operator that specifies repetition @var{n} times---that
+is, the preceding regular expression must match exactly @var{n} times
+in a row. For example, @samp{x\@{4\@}} matches the string @samp{xxxx}
+and nothing else.
+
+@item @kbd{\@{@var{n},@var{m}\@}}
+is a postfix operator that specifies repetition between @var{n} and
+@var{m} times---that is, the preceding regular expression must match
+at least @var{n} times, but no more than @var{m} times. If @var{m} is
+omitted, then there is no upper limit, but the preceding regular
+expression must match at least @var{n} times.@* @samp{\@{0,1\@}} is
+equivalent to @samp{?}. @* @samp{\@{0,\@}} is equivalent to
+@samp{*}. @* @samp{\@{1,\@}} is equivalent to @samp{+}.
+
+@item @kbd{[ @dots{} ]}
is a @dfn{character set}, which begins with @samp{[} and is terminated
by @samp{]}. In the simplest case, the characters between the two
brackets are what this set can match.
You can also include character ranges in a character set, by writing the
starting and ending characters with a @samp{-} between them. Thus,
-@samp{[a-z]} matches any lower-case ASCII letter. Ranges may be
+@samp{[a-z]} matches any lower-case @acronym{ASCII} letter. Ranges may be
intermixed freely with individual characters, as in @samp{[a-z$%.]},
-which matches any lower-case ASCII letter or @samp{$}, @samp{%} or
+which matches any lower-case @acronym{ASCII} letter or @samp{$}, @samp{%} or
period.
Note that the usual regexp special characters are not special inside a
and @samp{-}.
To include @samp{^} in a set, put it anywhere but at the beginning of
-the set.
+the set. (At the beginning, it complements the set---see below.)
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 @samp{A-z}
is somewhat ill-defined, and it may change in future Emacs versions.
-@item [^ @dots{} ]
+@item @kbd{[^ @dots{} ]}
@samp{[^} begins a @dfn{complemented character set}, which matches any
character except the ones specified. Thus, @samp{[^a-z0-9A-Z]} matches
-all characters @emph{except} letters and digits.
+all characters @emph{except} @acronym{ASCII} letters and digits.
@samp{^} is not special in a character set unless it is the first
character. The character following the @samp{^} is treated as if it
mentioned as one of the characters not to match. This is in contrast to
the handling of regexps in programs such as @code{grep}.
-@item ^
+@item @kbd{^}
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, @samp{^foo} matches a @samp{foo} that occurs at
the beginning of a line.
-@item $
+For historical compatibility reasons, @samp{^} can be used with this
+meaning only at the beginning of the regular expression, or after
+@samp{\(} or @samp{\|}.
+
+@item @kbd{$}
is similar to @samp{^} but matches only at the end of a line. Thus,
@samp{x+$} matches a string of one @samp{x} or more at the end of a line.
-@item \
+For historical compatibility reasons, @samp{$} can be used with this
+meaning only at the end of the regular expression, or before @samp{\)}
+or @samp{\|}.
+
+@item @kbd{\}
has two functions: it quotes the special characters (including
@samp{\}), and it introduces additional special constructs.
Because @samp{\} quotes special characters, @samp{\$} is a regular
expression that matches only @samp{$}, and @samp{\[} is a regular
expression that matches only @samp{[}, and so on.
+
+See the following section for the special constructs that begin
+with @samp{\}.
@end table
-Note: for historical compatibility, special characters are treated as
+ Note: for historical compatibility, special characters are treated as
ordinary ones if they are in contexts where their special meanings make no
sense. For example, @samp{*foo} treats @samp{*} as ordinary since there is
no preceding expression on which the @samp{*} can act. It is poor practice
to depend on this behavior; it is better to quote the special character anyway,
-regardless of where it appears.@refill
+regardless of where it appears.
-For the most part, @samp{\} followed by any character matches only that
-character. However, there are several exceptions: two-character
-sequences starting with @samp{\} that have special meanings. The second
-character in the sequence is always an ordinary character when used on
-its own. Here is a table of @samp{\} constructs.
+As a @samp{\} is not special inside a character alternative, it can
+never remove the special meaning of @samp{-} or @samp{]}. So you
+should not quote these characters when they have no special meaning
+either. This would not clarify anything, since backslashes can
+legitimately precede these characters where they @emph{have} special
+meaning, as in @samp{[^\]} (@code{"[^\\]"} for Lisp string syntax),
+which matches any single character except a backslash.
+
+@node Regexp Backslash
+@section Backslash in Regular Expressions
+
+ For the most part, @samp{\} followed by any character matches only
+that character. However, there are several exceptions: two-character
+sequences starting with @samp{\} 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 @samp{\} constructs.
@table @kbd
@item \|
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 @samp{\( @dots{} \)} construct. In practice
-there is almost no conflict between the two meanings.
+there is usually no conflict between the two meanings; when there is
+a conflict, you can use a ``shy'' group.
@item \(?: @dots{} \)
-is another grouping construct (often called ``shy'') that serves the same
-first two purposes, but not the third:
-it cannot be referred to later on by number. This is only useful
-for mechanically constructed regular expressions where grouping
-constructs need to be introduced implicitly and hence risk changing the
-numbering of subsequent groups.
+@cindex shy group, in regexp
+specifies a ``shy'' group that does not record the matched substring;
+you can't refer back to it with @samp{\@var{d}}. This is useful
+in mechanically combining regular expressions, so that you
+can add groups for syntactic purposes without interfering with
+the numbering of the groups that are meant to be referred to.
@item \@var{d}
+@cindex back reference, in regexp
matches the same text that matched the @var{d}th occurrence of a
-@samp{\( @dots{} \)} construct.
+@samp{\( @dots{} \)} construct. This is called a @dfn{back
+reference}.
After the end of a @samp{\( @dots{} \)} construct, the matcher remembers
the beginning and end of the text matched by that construct. Then,
match is recorded.
@item \`
-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 beginning of the string or
+buffer (or its accessible portion) being matched against.
@item \'
-matches the empty string, but only at the end of
-the buffer or string being matched against.
+matches the empty string, but only at the end of the string or buffer
+(or its accessible portion) being matched against.
@item \=
matches the empty string, but only at point.
@item \W
matches any character that is not a word-constituent.
+@item \_<
+matches the empty string, but only at the beginning of a symbol.
+A symbol is a sequence of one or more symbol-constituent characters.
+A symbol-constituent character is a character whose syntax is either
+@samp{w} or @samp{_}. @samp{\_<} matches at the beginning of the
+buffer only if a symbol-constituent character follows.
+
+@item \_>
+matches the empty string, but only at the end of a symbol. @samp{\_>}
+matches at the end of the buffer only if the contents end with a
+symbol-constituent character.
+
@item \s@var{c}
matches any character whose syntax is @var{c}. Here @var{c} is a
-character that represents a syntax code: thus, @samp{w} for word
-constituent, @samp{-} for whitespace, @samp{(} for open parenthesis,
-etc. Represent a character of whitespace (which can be a newline) by
-either @samp{-} or a space character.
+character that designates a particular syntax class: thus, @samp{w}
+for word constituent, @samp{-} or @samp{ } for whitespace, @samp{.}
+for ordinary punctuation, etc. @xref{Syntax}.
@item \S@var{c}
matches any character whose syntax is not @var{c}.
The constructs that pertain to words and syntax are controlled by the
setting of the syntax table (@pxref{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.
-@samp{\"} stands for a double-quote as part of the regexp, @samp{\\} for a
-backslash as part of the regexp, @samp{\t} for a tab and @samp{\n} for a
-newline.
+@node Regexp Example
+@section Regular Expression Example
+
+ Here is a complicated regexp---a simplified version of the regexp
+that Emacs uses, by default, to recognize the end of a sentence
+together with any whitespace that follows. We show its Lisp syntax to
+distinguish the spaces from the tab characters. In Lisp syntax, the
+string constant begins and ends with a double-quote. @samp{\"} stands
+for a double-quote as part of the regexp, @samp{\\} for a backslash as
+part of the regexp, @samp{\t} for a tab, and @samp{\n} for a newline.
@example
-"[.?!][]\"')]*\\($\\|\t\\| \\)[ \t\n]*"
+"[.?!][]\"')]*\\($\\| $\\|\t\\| \\)[ \t\n]*"
@end example
@noindent
-This contains four parts in succession: a character set matching period,
-@samp{?}, or @samp{!}; 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 @key{TAB} to
-enter a tab, and @kbd{C-j} to enter a newline. You would also type
-single backslashes as themselves, instead of doubling them for Lisp syntax.
-
-@findex re-builder
-@cindex authoring regular expressions
- For easier authoring of regular expressions, you can use the @kbd{M-x
-re-builder} command. It provides a convenient interface for creating
-regular expressions, by giving immediate visual feedback. The buffer
-from which @code{re-builder} was invoked becomes the target for the
-regexp editor, which pops in a separate window. Text that matches the
-regular expression you typed so far is color marked in the target
-buffer. Each parenthesized sub-expression of the regexp is shown in a
-distinct face, which makes it easier to verify even very complex
-regexps. (On displays that don't support colors, Emacs blinks the
-cursor around the matched text, like it does for matching parens.)
-
-@node Search Case, Replace, Regexps, Search
+This contains four parts in succession: a character set matching
+period, @samp{?}, or @samp{!}; a character set matching
+close-brackets, quotes, or parentheses, repeated zero or more times; a
+set of alternatives within backslash-parentheses that matches either
+end-of-line, a space at the end of a line, a tab, or two spaces; and a
+character set matching whitespace characters, repeated any number of
+times.
+
+ To enter the same regexp in incremental search, you would type
+@key{TAB} to enter a tab, and @kbd{C-j} to enter a newline. You would
+also type single backslashes as themselves, instead of doubling them
+for Lisp syntax. In commands that use ordinary minibuffer input to
+read a regexp, you would quote the @kbd{C-j} by preceding it with a
+@kbd{C-q} to prevent @kbd{C-j} from exiting the minibuffer.
+
+@node Search Case
@section Searching and Case
-@vindex case-fold-search
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 @samp{foo}, then @samp{Foo} and
well as to string search. The effect ceases if you delete the
upper-case letter from the search string.
+ Typing @kbd{M-c} within an incremental search toggles the case
+sensitivity of that search. The effect does not extend beyond the
+current incremental search to the next one, but it does override the
+effect of including an upper-case letter in the current search.
+
+@vindex case-fold-search
+@vindex default-case-fold-search
If you set the variable @code{case-fold-search} to @code{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. @xref{Locals}.
-This variable applies to nonincremental searches also, including those
-performed by the replace commands (@pxref{Replace}) and the minibuffer
-history matching commands (@pxref{Minibuffer History}).
-
-@node Replace, Other Repeating Search, Search Case, Search
+there is a default value in @code{default-case-fold-search} that you
+can also set. @xref{Locals}. This variable applies to nonincremental
+searches also, including those performed by the replace commands
+(@pxref{Replace}) and the minibuffer history matching commands
+(@pxref{Minibuffer History}).
+
+ Several related variables control case-sensitivity of searching and
+matching for specific commands or activities. For instance,
+@code{tags-case-fold-search} controls case sensitivity for
+@code{find-tag}. To find these variables, do @kbd{M-x
+apropos-variable @key{RET} case-fold-search @key{RET}}.
+
+@node Replace
@section Replacement Commands
@cindex replacement
@cindex search-and-replace commands
@cindex string substitution
@cindex global substitution
- Global search-and-replace operations are not needed as often in Emacs
-as they are in other editors@footnote{In some editors,
-search-and-replace operations are the only convenient way to make a
-single change in the text.}, but they are available. In addition to the
-simple @kbd{M-x replace-string} command which is like that found in most
-editors, there is a @kbd{M-x query-replace} command which asks you, for
-each occurrence of the pattern, whether to replace it.
+ Global search-and-replace operations are not needed often in Emacs,
+but they are available. In addition to the simple @kbd{M-x
+replace-string} command which replaces all occurrences,
+there is @kbd{M-%} (@code{query-replace}), which presents each occurrence
+of the pattern and asks you 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
-@code{expand-region-abbrevs} (@pxref{Expanding Abbrevs}).
+end of the buffer; however, in Transient Mark mode (@pxref{Transient
+Mark}), when the mark is active, they operate on the region. The
+basic replace commands replace one string (or regexp) with one
+replacement string. It is possible to perform several replacements in
+parallel using the command @code{expand-region-abbrevs}
+(@pxref{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.
+* 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.
@end menu
@node Unconditional Replace, Regexp Replace, Replace, Replace
@subsection Unconditional Replacement
@findex replace-string
-@findex replace-regexp
@table @kbd
@item M-x replace-string @key{RET} @var{string} @key{RET} @var{newstring} @key{RET}
Replace every occurrence of @var{string} with @var{newstring}.
-@item M-x replace-regexp @key{RET} @var{regexp} @key{RET} @var{newstring} @key{RET}
-Replace every match for @var{regexp} with @var{newstring}.
@end table
To replace every instance of @samp{foo} after point with @samp{bar},
A numeric argument restricts replacement to matches that are surrounded
by word boundaries. The argument's value doesn't matter.
+ What if you want to exchange @samp{x} and @samp{y}: replace every @samp{x} with a @samp{y} and vice versa? You can do it this way:
+
+@example
+M-x replace-string @key{RET} x @key{RET} @@TEMP@@ @key{RET}
+M-< M-x replace-string @key{RET} y @key{RET} x @key{RET}
+M-< M-x replace-string @key{RET} @@TEMP@@ @key{RET} y @key{RET}
+@end example
+
+@noindent
+This works provided the string @samp{@@TEMP@@} does not appear
+in your text.
+
@node Regexp Replace, Replacement and Case, Unconditional Replace, Replace
@subsection Regexp Replacement
+@findex replace-regexp
The @kbd{M-x replace-string} command replaces exact matches for a
single string. The similar command @kbd{M-x replace-regexp} replaces
any match for a specified pattern.
- In @code{replace-regexp}, the @var{newstring} need not be constant: it
-can refer to all or part of what is matched by the @var{regexp}.
-@samp{\&} in @var{newstring} stands for the entire match being replaced.
-@samp{\@var{d}} in @var{newstring}, where @var{d} is a digit, stands for
-whatever matched the @var{d}th parenthesized grouping in @var{regexp}.
-To include a @samp{\} in the text to replace with, you must enter
-@samp{\\}. For example,
+@table @kbd
+@item M-x replace-regexp @key{RET} @var{regexp} @key{RET} @var{newstring} @key{RET}
+Replace every match for @var{regexp} with @var{newstring}.
+@end table
+
+@cindex back reference, in regexp replacement
+ In @code{replace-regexp}, the @var{newstring} need not be constant:
+it can refer to all or part of what is matched by the @var{regexp}.
+@samp{\&} in @var{newstring} stands for the entire match being
+replaced. @samp{\@var{d}} in @var{newstring}, where @var{d} is a
+digit, stands for whatever matched the @var{d}th parenthesized
+grouping in @var{regexp}. (This is called a ``back reference''.)
+@samp{\#} refers to the count of replacements already made in this
+command, as a decimal number. In the first replacement, @samp{\#}
+stands for @samp{0}; in the second, for @samp{1}; and so on. For
+example,
@example
M-x replace-regexp @key{RET} c[ad]+r @key{RET} \&-safe @key{RET}
@end example
@noindent
-performs the inverse transformation.
+performs the inverse transformation. To include a @samp{\} in the
+text to replace with, you must enter @samp{\\}.
+
+ If you want to enter part of the replacement string by hand each
+time, use @samp{\?} in the replacement string. Each replacement will
+ask you to edit the replacement string in the minibuffer, putting
+point where the @samp{\?} was.
+
+ The remainder of this subsection is intended for specialized tasks
+and requires knowledge of Lisp. Most readers can skip it.
+
+ You can use Lisp expressions to calculate parts of the
+replacement string. To do this, write @samp{\,} followed by the
+expression in the replacement string. Each replacement calculates the
+value of the expression and converts it to text without quoting (if
+it's a string, this means using the string's contents), and uses it in
+the replacement string in place of the expression itself. If the
+expression is a symbol, one space in the replacement string after the
+symbol name goes with the symbol name, so the value replaces them
+both.
+
+ Inside such an expression, you can use some special sequences.
+@samp{\&} and @samp{\@var{n}} refer here, as usual, to the entire
+match as a string, and to a submatch as a string. @var{n} may be
+multiple digits, and the value of @samp{\@var{n}} is @code{nil} if
+subexpression @var{n} did not match. You can also use @samp{\#&} and
+@samp{\#@var{n}} to refer to those matches as numbers (this is valid
+when the match or submatch has the form of a numeral). @samp{\#} here
+too stands for the number of already-completed replacements.
+
+ Repeating our example to exchange @samp{x} and @samp{y}, we can thus
+do it also this way:
+
+@example
+M-x replace-regexp @key{RET} \(x\)\|y @key{RET}
+\,(if \1 "y" "x") @key{RET}
+@end example
+
+ For computing replacement strings for @samp{\,}, the @code{format}
+function is often useful (@pxref{Formatting Strings,,, elisp, The Emacs
+Lisp Reference Manual}). For example, to add consecutively numbered
+strings like @samp{ABC00042} to columns 73 @w{to 80} (unless they are
+already occupied), you can use
+
+@example
+M-x replace-regexp @key{RET} ^.\@{0,72\@}$ @key{RET}
+\,(format "%-72sABC%05d" \& \#) @key{RET}
+@end example
@node Replacement and Case, Query Replace, Regexp Replace, Replace
@subsection 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
+command ignores case while searching for occurrences to
replace---provided @code{case-fold-search} is non-@code{nil}. If
@code{case-fold-search} is set to @code{nil}, case is always significant
in all searches.
@samp{bar}, not all of them, then you cannot use an ordinary
@code{replace-string}. Instead, use @kbd{M-%} (@code{query-replace}).
This command finds occurrences of @samp{foo} one by one, displays each
-occurrence and asks you whether to replace it. A numeric argument to
-@code{query-replace} tells it to consider only occurrences that are
-bounded by word-delimiter characters. This preserves case, just like
-@code{replace-string}, provided @code{case-replace} is non-@code{nil},
-as it normally is.
+occurrence and asks you whether to replace it. Aside from querying,
+@code{query-replace} works just like @code{replace-string}. It
+preserves case, like @code{replace-string}, provided
+@code{case-replace} is non-@code{nil}, as it normally is. A numeric
+argument means consider only occurrences that are bounded by
+word-delimiter characters.
@kindex C-M-%
@findex query-replace-regexp
- Aside from querying, @code{query-replace} works just like
-@code{replace-string}, and @code{query-replace-regexp} works just like
-@code{replace-regexp}. This command is run by @kbd{C-M-%}.
+ @kbd{C-M-%} performs regexp search and replace (@code{query-replace-regexp}).
+It works like @code{replace-regexp} except that it queries
+like @code{query-replace}.
- The things you can type when you are shown an occurrence of @var{string}
-or a match for @var{regexp} are:
+@cindex faces for highlighting query replace
+ These commands highlight the current match using the face
+@code{query-replace}. They highlight other matches using
+@code{lazy-highlight} just like incremental search (@pxref{Incremental
+Search}).
+
+ The characters you can type when you are shown a match for the string
+or regexp are:
@ignore @c Not worth it.
@kindex SPC @r{(query-replace)}
@item ^
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 @kbd{^} in a row is meaningful, because
-only one previous replacement position is kept during @code{query-replace}.
+be an occurrence), in case you changed it by mistake or want to
+reexamine it.
@item C-r
to enter a recursive editing level, in case the occurrence needs to be
occurrence of @var{string}. When done, exit the recursive editing level
with @kbd{C-M-c} to proceed to the next occurrence.
+@item e
+to edit the replacement string in the minibuffer. When you exit the
+minibuffer by typing @key{RET}, the minibuffer contents replace the
+current occurrence of the pattern. They also become the new
+replacement string for any further occurrences.
+
@item C-l
to redisplay the screen. Then you must type another character to
specify what to do with this occurrence.
-@item e
-to let you edit the replacement string.
-
@item C-h
to display a message summarizing these options. Then you must type
another character to specify what to do with this occurrence.
See also @ref{Transforming File Names}, for Dired commands to rename,
copy, or link files by replacing regexp matches in file names.
-@node Other Repeating Search,, Replace, Search
+@node Other Repeating Search
@section 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 @code{case-fold-search} is non-@code{nil}.
+expression. They all ignore case in matching, if the pattern contains
+no upper-case letters and @code{case-fold-search} is non-@code{nil}.
+Aside from @code{occur} and its variants, all operate on the text from
+point to the end of the buffer, or on the active region in Transient
+Mark mode.
@findex list-matching-lines
@findex occur
+@findex multi-occur
+@findex multi-occur-in-matching-buffers
@findex how-many
@findex delete-non-matching-lines
@findex delete-matching-lines
@table @kbd
@item M-x occur @key{RET} @var{regexp} @key{RET}
-Display a list showing each line in the buffer that contains a match for
-@var{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
-(@pxref{Narrowing}).
+Display a list showing each line in the buffer that contains a match
+for @var{regexp}. To limit the search to part of the buffer, narrow
+to that part (@pxref{Narrowing}). A numeric argument @var{n}
+specifies that @var{n} lines of context are to be displayed before and
+after each matching line. Currently, @code{occur} can not correctly
+handle multiline matches.
@kindex RET @r{(Occur mode)}
+@kindex o @r{(Occur mode)}
+@kindex C-o @r{(Occur mode)}
The buffer @samp{*Occur*} containing the output serves as a menu for
-finding the occurrences in their original context. Click @kbd{Mouse-2}
-on an occurrence listed in @samp{*Occur*}, or position point there and
-type @key{RET}; this switches to the buffer that was searched and
-moves point to the original of the chosen occurrence.
+finding the occurrences in their original context. Click
+@kbd{Mouse-2} on an occurrence listed in @samp{*Occur*}, or position
+point there and type @key{RET}; this switches to the buffer that was
+searched and moves point to the original of the chosen occurrence.
+@kbd{o} and @kbd{C-o} display the match in another window; @kbd{C-o}
+does not select it.
+
+After using @kbd{M-x occur}, you can use @code{next-error} to visit
+the occurrences found, one by one. @ref{Compilation Mode}.
@item M-x list-matching-lines
Synonym for @kbd{M-x occur}.
+@item M-x multi-occur @key{RET} @var{buffers} @key{RET} @var{regexp} @key{RET}
+This function is just like @code{occur}, except it is able to search
+through multiple buffers. It asks you to specify the buffer names one by one.
+
+@item M-x multi-occur-in-matching-buffers @key{RET} @var{bufregexp} @key{RET} @var{regexp} @key{RET}
+This function is similar to @code{multi-occur}, except the buffers to
+search are specified by a regular expression that matches visited
+filenames. With a prefix argument, it uses the regular expression to match
+buffer names instead.
+
@item M-x how-many @key{RET} @var{regexp} @key{RET}
-Print the number of matches for @var{regexp} after point, or in the
-active region in Transient Mark mode.
+Print the number of matches for @var{regexp} that exist in the buffer
+after point. In Transient Mark mode, if the region is active, the
+command operates on the region instead.
@item M-x flush-lines @key{RET} @var{regexp} @key{RET}
-Delete each line after point, or in the active region in Transient Mark
-mode, that contains a match for @var{regexp}.
+This command deletes each line that contains a match for @var{regexp},
+operating on the text after point; it deletes the current line
+if it contains a match starting after point. In Transient Mark mode,
+if the region is active, the command operates on the region instead;
+it deletes a line partially contained in the region if it contains a
+match entirely contained in the region.
+
+If a match is split across lines, @code{flush-lines} deletes all those
+lines. It deletes the lines before starting to look for the next
+match; hence, it ignores a match starting on the same line at which
+another match ended.
@item M-x keep-lines @key{RET} @var{regexp} @key{RET}
-Delete each line that follows point, or is in the active region in
-Transient Mark mode, and @emph{does not} contain a match for
-@var{regexp}.
+This command deletes each line that @emph{does not} contain a match for
+@var{regexp}, operating on the text after point; if point is not at the
+beginning of a line, it always keeps the current line. In Transient
+Mark mode, if the region is active, the command operates on the region
+instead; it never deletes lines that are only partially contained in
+the region (a newline that ends a line counts as part of that line).
+
+If a match is split across lines, this command keeps all those lines.
@end table
- Searching and replacing can be performed under the control of tags
-files (@pxref{Tags Search}) and Dired (@pxref{Operating on Files}).
+ You can also search multiple files under control of a tags table
+(@pxref{Tags Search}) or through the Dired @kbd{A} command
+(@pxref{Operating on Files}), or ask the @code{grep} program to do it
+(@pxref{Grep Searching}).
- In addition, you can use @code{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. @xref{Grep Searching}.
+@ignore
+ arch-tag: fd9d8e77-66af-491c-b212-d80999613e3e
+@end ignore