@c This is part of the Emacs manual.
-@c Copyright (C) 1985, 86, 87, 93, 94, 95, 97, 2000, 2001
-@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
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 a forward incremental search. It reads characters
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 just after the first @samp{FO} (the @samp{F} in that
+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 after the first @samp{FOO} after the place
+@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.
@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}, @kbd{M-s}, and some other
+@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 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
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
@samp{FOOT}). A second @kbd{C-g} at that point cancels the search
entirely, returning point to where it was when the search started.
+@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
+found what you specified and is waiting for input, @kbd{C-g} cancels the
+entire search. The cursor moves back to where you started the search. If
+@kbd{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 @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}.
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.
-@cindex searching for non-ASCII characters
+ @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}.
+
+ 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 search for non-ASCII characters, 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:
+
+ 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}]:
name of the input method. The input method you enable during
incremental search remains enabled in the current buffer afterwards.
- 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.
-
-@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
-found what you specified and is waiting for input, @kbd{C-g} cancels the
-entire search. The cursor moves back to where you started the search. If
-@kbd{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 @kbd{C-g}
-will cancel the entire search.
-
- 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}.
+@node Isearch Yank
+@subsection Isearch Yanking
-@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
+ 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
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. 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.
+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.
@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
@vindex isearch-lazy-highlight
+
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}
If you don't like this feature, you can turn it off by setting
@code{isearch-lazy-highlight} to @code{nil}.
-@vindex isearch-lazy-highlight-face
@cindex faces for highlighting search matches
You can control how this highlighting looks by customizing the faces
-@code{isearch} (used for the current match) and
-@code{isearch-lazy-highlight-face} (for all the other matches).
+@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
@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. See @code{baud-rate} in @ref{Display Custom}.
+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
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 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
@code{word-search-forward} and @code{word-search-backward}. These
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 suitable key sequences for them.
+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. GNU Emacs provides both incremental and
-nonincremental ways to search for a match for a regexp.
+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}), or by invoking @kbd{C-s} with a
-prefix argument (whose value does not matter). This command reads a
+(@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}), or @kbd{C-r} with a prefix argument.
+(@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 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{$},
-@samp{^}, @samp{.}, @samp{*}, @samp{+}, @samp{?}, @samp{[}, @samp{]} and
-@samp{\}. Any other character appearing in a regular expression is
-ordinary, unless a @samp{\} precedes it. (When you use regular
-expressions in a Lisp program, each @samp{\} must be doubled, see the
-example near the end of this section.)
+@samp{^}, @samp{.}, @samp{*}, @samp{+}, @samp{?}, @samp{[}, and
+@samp{\}. The character @samp{]} is special if it ends a character
+alternative (see later). The character @samp{-} is special inside a
+character alternative. Any other character appearing in a regular
+expression is ordinary, unless a @samp{\} precedes it. (When you use
+regular expressions in a Lisp program, each @samp{\} must be doubled,
+see the example near the end of this section.)
For example, @samp{f} is not a special character, so it is ordinary, and
therefore @samp{f} is a regular expression that matches the string
You can also include character ranges in a character set, by writing the
starting and ending characters with a @samp{-} between them. Thus,
-@samp{[a-z]} matches any lower-case ASCII letter. Ranges may be
+@samp{[a-z]} matches any lower-case @acronym{ASCII} letter. Ranges may be
intermixed freely with individual characters, as in @samp{[a-z$%.]},
-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
@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} ASCII 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
match anything. Thus, @samp{^foo} matches a @samp{foo} that occurs at
the beginning of a line.
+For historical compatibility reasons, @samp{^} can be used with this
+meaning only at the beginning of the regular expression, or after
+@samp{\(} or @samp{\|}.
+
@item @kbd{$}
is similar to @samp{^} but matches only at the end of a line. Thus,
@samp{x+$} matches a string of one @samp{x} or more at the end of a line.
+For historical compatibility reasons, @samp{$} can be used with this
+meaning only at the end of the regular expression, or before @samp{\)}
+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{\[} is a regular
expression that matches only @samp{[}, and so on.
+
+See the following section for the special constructs that begin
+with @samp{\}.
@end table
-Note: for historical compatibility, special characters are treated as
+ Note: for historical compatibility, special characters are treated as
ordinary ones if they are in contexts where their special meanings make no
sense. For example, @samp{*foo} treats @samp{*} as ordinary since there is
no preceding expression on which the @samp{*} can act. It is poor practice
to depend on this behavior; it is better to quote the special character anyway,
-regardless of where it appears.@refill
+regardless of where it appears.
+
+As a @samp{\} is not special inside a character alternative, it can
+never remove the special meaning of @samp{-} or @samp{]}. So you
+should not quote these characters when they have no special meaning
+either. This would not clarify anything, since backslashes can
+legitimately precede these characters where they @emph{have} special
+meaning, as in @samp{[^\]} (@code{"[^\\]"} for Lisp string syntax),
+which matches any single character except a backslash.
-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.
+@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 \|
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 were written by the user.
+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,
@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 designates a particular syntax class: thus, @samp{w}
The constructs that pertain to words and syntax are controlled by the
setting of the syntax table (@pxref{Syntax}).
- Here is a complicated regexp, stored in @code{sentence-end} and used
-by Emacs 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.
+@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]*"
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.
-@ignore
-@c I commented this out because it is missing vital information
-@c and therefore useless. For instance, what do you do to *use* the
-@c regular expression when it is finished? What jobs is this good for?
-@c -- rms
-
-@findex re-builder
-@cindex authoring regular expressions
- For convenient interactive development 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. At
-all times, all the matches in the target buffer for the current
-regular expression are highlighted. 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, as it does
-for matching parens.)
-@end ignore
-
-@node Search Case, Replace, Regexps, Search
+@node Search Case
@section Searching and Case
Incremental searches in Emacs normally ignore the case of the text
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
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 is like that found in most editors,
-there is a @kbd{M-x query-replace} command which finds each occurrence
+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 (@pxref{Transient
Mark}), when the mark is active, they operate on the region. The
-replace commands all replace one string (or regexp) with one
+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},
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 query-replace @key{RET} x @key{RET} @@TEMP@@ @key{RET}
-M-x query-replace @key{RET} y @key{RET} x @key{RET}
-M-x query-replace @key{RET} @@TEMP@@ @key{RET} y @key{RET}
+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
@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
@kindex C-M-%
@findex query-replace-regexp
@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}.
+
+@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:
@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
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
@findex list-matching-lines
@findex occur
@findex multi-occur
-@findex multi-occur-by-filename-regexp
+@findex multi-occur-in-matching-buffers
@findex how-many
@findex delete-non-matching-lines
@findex delete-matching-lines
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.
+after each matching line. Currently, @code{occur} can not correctly
+handle multiline matches.
@kindex RET @r{(Occur mode)}
@kindex o @r{(Occur mode)}
@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.
+through multiple buffers. It asks you to specify the buffer names one by one.
-@item M-x multi-occur-by-filename-regexp @key{RET} @var{bufregexp} @key{RET} @var{regexp} @key{RET}
+@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 regexp on their filename.
+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} that exist in the buffer
command operates on the region instead.
@item M-x flush-lines @key{RET} @var{regexp} @key{RET}
-Delete each line that contains a match for @var{regexp}, operating on
-the text after point. In Transient Mark mode, if the region is
-active, the command operates on the region instead.
+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 @emph{does not} contain a match for
-@var{regexp}, operating on the text after point. In Transient Mark
-mode, if the region is active, the command operates on the region
-instead.
+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
You can also search multiple files under control of a tags table
-(@pxref{Tags Search}) or through Dired @kbd{A} command
+(@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}).
+
+@ignore
+ arch-tag: fd9d8e77-66af-491c-b212-d80999613e3e
+@end ignore