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+@c This is part of the Emacs manual.
+@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc.
+@c See file emacs.texi for copying conditions.
+@node Search, Fixit, Display, Top
+@chapter Searching and Replacement
+@cindex searching
+@cindex finding strings within text
+
+  Like other editors, Emacs has commands for searching for occurrences of
+a string.  The principal search command is unusual in that it is
+@dfn{incremental}; it begins to search before you have finished typing the
+search string.  There are also nonincremental search commands more like
+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.
+
+@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.
+@end menu
+
+@node Incremental Search, Nonincremental Search, Search, 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
+found.  When you have typed enough characters to identify the place you
+want, you can stop.  Depending on what you plan to do next, you may or
+may not need to terminate the search explicitly with @key{RET}.
+
+@c WideCommands
+@table @kbd
+@item C-s
+Incremental search forward (@code{isearch-forward}).
+@item C-r
+Incremental search backward (@code{isearch-backward}).
+@end table
+
+@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.
+
+  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
+search string.  This does not happen until Emacs is ready to read another
+input character; first it must either find, or fail to find, the character
+you want to erase.  If you do not want to wait for this to happen, use
+@kbd{C-g} as described below.
+
+  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
+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}).
+
+  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}.
+
+  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.''
+
+  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}
+to terminate editing the string and search for it.
+
+  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}, you might see the cursor after the @samp{FOO} in @samp{FOOL}.
+At this point there are several things you can do.  If your string was
+mistyped, you can rub some of it out and correct it.  If you like the place
+you have found, you can type @key{RET} or some other Emacs command to
+``accept what the search offered.''  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}.
+
+  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
+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.
+
+  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
+to its use for insertion (@pxref{Inserting Text}): it causes the
+following character to be treated the way any ``ordinary'' character is
+treated in the same context.  You can also specify a character by its
+octal code: enter @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}.
+
+@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.
+
+  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.
+@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.
+
+@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}}.
+
+@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
+on the screen.
+
+  When you terminate the search, the single-line window is removed.
+Then Emacs redisplays the window in which the search was done, to show
+its new position of point.
+
+@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.
+
+@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
+@section Nonincremental Search
+@cindex nonincremental search
+
+  Emacs also has conventional nonincremental search commands, which require
+you to type the entire search string before searching begins.
+
+@table @kbd
+@item C-s @key{RET} @var{string} @key{RET}
+Search for @var{string}.
+@item C-r @key{RET} @var{string} @key{RET}
+Search backward for @var{string}.
+@end table
+
+  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.
+@ifinfo
+@xref{Word Search}.
+@end ifinfo
+
+@findex search-forward
+@findex search-backward
+  Forward and backward nonincremental searches are implemented by the
+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
+for them.
+
+@node Word Search, Regexp Search, Nonincremental Search, 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.
+
+  Word search is useful for editing a printed document made with a text
+formatter.  If you edit while looking at the printed, formatted version,
+you can't tell where the line breaks are in the source file.  With word
+search, you can search without having to know them.
+
+@table @kbd
+@item C-s @key{RET} C-w @var{words} @key{RET}
+Search for @var{words}, ignoring details of punctuation.
+@item C-r @key{RET} C-w @var{words} @key{RET}
+Search backward for @var{words}, ignoring details of punctuation.
+@end table
+
+  Word search is a special case of nonincremental search and is invoked
+with @kbd{C-s @key{RET} C-w}.  This is followed by the search string,
+which must always be terminated with @key{RET}.  Being nonincremental,
+this search does not start until the argument is terminated.  It works
+by constructing a regular expression and searching for that; see
+@ref{Regexp Search}.
+
+  Use @kbd{C-r @key{RET} C-w} to do backward word search.
+
+@findex word-search-forward
+@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.
+
+@node Regexp Search, Regexps, Word Search, 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.
+
+@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.
+
+  All of the control characters that do special things within an
+ordinary incremental search have the same function in incremental regexp
+search.  Typing @kbd{C-s} or @kbd{C-r} immediately after starting the
+search retrieves the last incremental search regexp used; that is to
+say, incremental regexp and non-regexp searches have independent
+defaults.  They also have separate search rings that you can access with
+@kbd{M-p} and @kbd{M-n}.
+
+  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}}.
+
+  Note that adding characters to the regexp in an incremental regexp
+search can make the cursor move back and start again.  For example, if
+you have searched for @samp{foo} and you add @samp{\|bar}, the cursor
+backs up in case the first @samp{bar} precedes the first @samp{foo}.
+
+@findex re-search-forward
+@findex re-search-backward
+  Nonincremental search for a regexp is done by the functions
+@code{re-search-forward} and @code{re-search-backward}.  You can invoke
+these with @kbd{M-x}, or bind them to keys, or invoke them by way of
+incremental regexp search with @kbd{C-M-s @key{RET}} and @kbd{C-M-r
+@key{RET}}.
+
+  If you use the incremental regexp search commands with a prefix
+argument, they perform ordinary string search, like
+@code{isearch-forward} and @code{isearch-backward}.  @xref{Incremental
+Search}.
+
+@node Regexps, Search Case, Regexp Search, Search
+@section Syntax of Regular Expressions
+@cindex regexp syntax
+
+  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.
+
+  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
+@samp{f} and no other string.  (It does @emph{not} match the string
+@samp{ff}.)  Likewise, @samp{o} is a regular expression that matches
+only @samp{o}.  (When case distinctions are being ignored, these regexps
+also match @samp{F} and @samp{O}, but we consider this a generalization
+of ``the same string,'' rather than an exception.)
+
+  Any two regular expressions @var{a} and @var{b} can be concatenated.  The
+result is a regular expression which matches a string if @var{a} matches
+some amount of the beginning of that string and @var{b} matches the rest of
+the string.@refill
+
+  As a simple example, we can concatenate the regular expressions @samp{f}
+and @samp{o} to get the regular expression @samp{fo}, which matches only
+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)}
+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 *
+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
+@samp{o}s).
+
+@samp{*} always applies to the @emph{smallest} possible preceding
+expression.  Thus, @samp{fo*} has a repeating @samp{o}, not a repeating
+@samp{fo}.  It matches @samp{f}, @samp{fo}, @samp{foo}, and so on.
+
+The matcher processes a @samp{*} construct by matching, immediately,
+as many repetitions as can be found.  Then it continues with the rest
+of the pattern.  If that fails, backtracking occurs, discarding some
+of the matches of the @samp{*}-modified construct in case that makes
+it possible to match the rest of the pattern.  For example, in matching
+@samp{ca*ar} against the string @samp{caaar}, the @samp{a*} first
+tries to match all three @samp{a}s; but the rest of the pattern is
+@samp{ar} and there is only @samp{r} left to match, so this try fails.
+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 +
+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 ?
+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 [ @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.
+
+Thus, @samp{[ad]} matches either one @samp{a} or one @samp{d}, and
+@samp{[ad]*} matches any string composed of just @samp{a}s and @samp{d}s
+(including the empty string), from which it follows that @samp{c[ad]*r}
+matches @samp{cr}, @samp{car}, @samp{cdr}, @samp{caddaar}, etc.
+
+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
+intermixed freely with individual characters, as in @samp{[a-z$%.]},
+which matches any lower-case ASCII letter or @samp{$}, @samp{%} or
+period.
+
+Note that the usual regexp special characters are not special inside a
+character set.  A completely different set of special characters exists
+inside character sets: @samp{]}, @samp{-} and @samp{^}.
+
+To include a @samp{]} in a character set, you must make it the first
+character.  For example, @samp{[]a]} matches @samp{]} or @samp{a}.  To
+include a @samp{-}, write @samp{-} as the first or last character of the
+set, or put it after a range.  Thus, @samp{[]-]} matches both @samp{]}
+and @samp{-}.
+
+To include @samp{^} in a set, put it anywhere but at the beginning of
+the set.
+
+When you use a range in case-insensitive search, you should write both
+ends of the range in upper case, or both in lower case, or both should
+be non-letters.  The behavior of a mixed-case range such as @samp{A-z}
+is somewhat ill-defined, and it may change in future Emacs versions.
+
+@item [^ @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.
+
+@samp{^} is not special in a character set unless it is the first
+character.  The character following the @samp{^} is treated as if it
+were first (in other words, @samp{-} and @samp{]} are not special there).
+
+A complemented character set can match a newline, unless newline is
+mentioned as one of the characters not to match.  This is in contrast to
+the handling of regexps in programs such as @code{grep}.
+
+@item ^
+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 $
+is similar to @samp{^} but matches only at the end of a line.  Thus,
+@samp{x+$} matches a string of one @samp{x} or more at the end of a line.
+
+@item \
+has two functions: it quotes the special characters (including
+@samp{\}), and it introduces additional special constructs.
+
+Because @samp{\} quotes special characters, @samp{\$} is a regular
+expression that matches only @samp{$}, and @samp{\[} is a regular
+expression that matches only @samp{[}, and so on.
+@end table
+
+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
+
+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 \|
+specifies an alternative.  Two regular expressions @var{a} and @var{b}
+with @samp{\|} in between form an expression that matches some text if
+either @var{a} matches it or @var{b} matches it.  It works by trying to
+match @var{a}, and if that fails, by trying to match @var{b}.
+
+Thus, @samp{foo\|bar} matches either @samp{foo} or @samp{bar}
+but no other string.@refill
+
+@samp{\|} applies to the largest possible surrounding expressions.  Only a
+surrounding @samp{\( @dots{} \)} grouping can limit the grouping power of
+@samp{\|}.@refill
+
+Full backtracking capability exists to handle multiple uses of @samp{\|}.
+
+@item \( @dots{} \)
+is a grouping construct that serves three purposes:
+
+@enumerate
+@item
+To enclose a set of @samp{\|} alternatives for other operations.
+Thus, @samp{\(foo\|bar\)x} matches either @samp{foox} or @samp{barx}.
+
+@item
+To enclose a complicated expression for the postfix operators @samp{*},
+@samp{+} and @samp{?} to operate on.  Thus, @samp{ba\(na\)*} matches
+@samp{bananana}, etc., with any (zero or more) number of @samp{na}
+strings.@refill
+
+@item
+To record a matched substring for future reference.
+@end enumerate
+
+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 no conflict between the two meanings.
+
+@item \@var{d}
+matches the same text that matched the @var{d}th occurrence of a
+@samp{\( @dots{} \)} construct.
+
+After the end of a @samp{\( @dots{} \)} construct, the matcher remembers
+the beginning and end of the text matched by that construct.  Then,
+later on in the regular expression, you can use @samp{\} followed by the
+digit @var{d} to mean ``match the same text matched the @var{d}th time
+by the @samp{\( @dots{} \)} construct.''
+
+The strings matching the first nine @samp{\( @dots{} \)} constructs
+appearing in a regular expression are assigned numbers 1 through 9 in
+the order that the open-parentheses appear in the regular expression.
+So you can use @samp{\1} through @samp{\9} to refer to the text matched
+by the corresponding @samp{\( @dots{} \)} constructs.
+
+For example, @samp{\(.*\)\1} matches any newline-free string that is
+composed of two identical halves.  The @samp{\(.*\)} matches the first
+half, which may be anything, but the @samp{\1} that follows must match
+the same exact text.
+
+If a particular @samp{\( @dots{} \)} construct matches more than once
+(which can easily happen if it is followed by @samp{*}), only the last
+match is recorded.
+
+@item \`
+matches the empty string, but only at the beginning
+of the buffer or string being matched against.
+
+@item \'
+matches the empty string, but only at the end of
+the buffer or string being matched against.
+
+@item \=
+matches the empty string, but only at point.
+
+@item \b
+matches the empty string, but only at the beginning or
+end of a word.  Thus, @samp{\bfoo\b} matches any occurrence of
+@samp{foo} as a separate word.  @samp{\bballs?\b} matches
+@samp{ball} or @samp{balls} as a separate word.@refill
+
+@samp{\b} matches at the beginning or end of the buffer
+regardless of what text appears next to it.
+
+@item \B
+matches the empty string, but @emph{not} at the beginning or
+end of a word.
+
+@item \<
+matches the empty string, but only at the beginning of a word.
+@samp{\<} matches at the beginning of the buffer only if a
+word-constituent character follows.
+
+@item \>
+matches the empty string, but only at the end of a word.  @samp{\>}
+matches at the end of the buffer only if the contents end with a
+word-constituent character.
+
+@item \w
+matches any word-constituent character.  The syntax table
+determines which characters these are.  @xref{Syntax}.
+
+@item \W
+matches any character that is not a word-constituent.
+
+@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.
+
+@item \S@var{c}
+matches any character whose syntax is not @var{c}.
+@end table
+
+  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.
+
+@example
+"[.?!][]\"')]*\\($\\|\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.
+
+@node Search Case, Replace, Regexps, Search
+@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
+@samp{foo} are also considered a match.  Regexps, and in particular
+character sets, are included: @samp{[ab]} would match @samp{a} or
+@samp{A} or @samp{b} or @samp{B}.@refill
+
+  An upper-case letter anywhere in the incremental search string makes
+the search case-sensitive.  Thus, searching for @samp{Foo} does not find
+@samp{foo} or @samp{FOO}.  This applies to regular expression search as
+well as to string search.  The effect ceases if you delete the
+upper-case letter from the search string.
+
+  If you set the variable @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
+@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.
+
+  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}).
+
+@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.
+@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},
+use the command @kbd{M-x replace-string} with the two arguments
+@samp{foo} and @samp{bar}.  Replacement happens only in the text after
+point, so if you want to cover the whole buffer you must go to the
+beginning first.  All occurrences up to the end of the buffer are
+replaced; to limit replacement to part of the buffer, narrow to that
+part of the buffer before doing the replacement (@pxref{Narrowing}).
+In Transient Mark mode, when the region is active, replacement is
+limited to the region (@pxref{Transient Mark}).
+
+  When @code{replace-string} exits, it leaves point at the last
+occurrence replaced.  It sets the mark to the prior position of point
+(where the @code{replace-string} command was issued); use @kbd{C-u
+C-@key{SPC}} to move back there.
+
+  A numeric argument restricts replacement to matches that are surrounded
+by word boundaries.  The argument's value doesn't matter.
+
+@node Regexp Replace, Replacement and Case, Unconditional Replace, Replace
+@subsection Regexp Replacement
+
+  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,
+
+@example
+M-x replace-regexp @key{RET} c[ad]+r @key{RET} \&-safe @key{RET}
+@end example
+
+@noindent
+replaces (for example) @samp{cadr} with @samp{cadr-safe} and @samp{cddr}
+with @samp{cddr-safe}.
+
+@example
+M-x replace-regexp @key{RET} \(c[ad]+r\)-safe @key{RET} \1 @key{RET}
+@end example
+
+@noindent
+performs the inverse transformation.
+
+@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
+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.
+
+@vindex case-replace
+  In addition, when the @var{newstring} argument is all or partly lower
+case, replacement commands try to preserve the case pattern of each
+occurrence.  Thus, the command
+
+@example
+M-x replace-string @key{RET} foo @key{RET} bar @key{RET}
+@end example
+
+@noindent
+replaces a lower case @samp{foo} with a lower case @samp{bar}, an
+all-caps @samp{FOO} with @samp{BAR}, and a capitalized @samp{Foo} with
+@samp{Bar}.  (These three alternatives---lower case, all caps, and
+capitalized, are the only ones that @code{replace-string} can
+distinguish.)
+
+  If upper-case letters are used in the replacement string, they remain
+upper case every time that text is inserted.  If upper-case letters are
+used in the first argument, the second argument is always substituted
+exactly as given, with no case conversion.  Likewise, if either
+@code{case-replace} or @code{case-fold-search} is set to @code{nil},
+replacement is done without case conversion.
+
+@node Query Replace,, Replacement and Case, Replace
+@subsection Query Replace
+@cindex query replace
+
+@table @kbd
+@item M-% @var{string} @key{RET} @var{newstring} @key{RET}
+@itemx M-x query-replace @key{RET} @var{string} @key{RET} @var{newstring} @key{RET}
+Replace some occurrences of @var{string} with @var{newstring}.
+@item C-M-% @var{regexp} @key{RET} @var{newstring} @key{RET}
+@itemx M-x query-replace-regexp @key{RET} @var{regexp} @key{RET} @var{newstring} @key{RET}
+Replace some matches for @var{regexp} with @var{newstring}.
+@end table
+
+@kindex M-%
+@findex query-replace
+  If you want to change only some of the occurrences of @samp{foo} to
+@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.
+
+@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-%}.
+
+  The things you can type when you are shown an occurrence of @var{string}
+or a match for @var{regexp} are:
+
+@ignore @c Not worth it.
+@kindex SPC @r{(query-replace)}
+@kindex DEL @r{(query-replace)}
+@kindex , @r{(query-replace)}
+@kindex RET @r{(query-replace)}
+@kindex . @r{(query-replace)}
+@kindex ! @r{(query-replace)}
+@kindex ^ @r{(query-replace)}
+@kindex C-r @r{(query-replace)}
+@kindex C-w @r{(query-replace)}
+@kindex C-l @r{(query-replace)}
+@end ignore
+
+@c WideCommands
+@table @kbd
+@item @key{SPC}
+to replace the occurrence with @var{newstring}.
+
+@item @key{DEL}
+to skip to the next occurrence without replacing this one.
+
+@item , @r{(Comma)}
+to replace this occurrence and display the result.  You are then asked
+for another input character to say what to do next.  Since the
+replacement has already been made, @key{DEL} and @key{SPC} are
+equivalent in this situation; both move to the next occurrence.
+
+You can type @kbd{C-r} at this point (see below) to alter the replaced
+text.  You can also type @kbd{C-x u} to undo the replacement; this exits
+the @code{query-replace}, so if you want to do further replacement you
+must use @kbd{C-x @key{ESC} @key{ESC} @key{RET}} to restart
+(@pxref{Repetition}).
+
+@item @key{RET}
+to exit without doing any more replacements.
+
+@item .@: @r{(Period)}
+to replace this occurrence and then exit without searching for more
+occurrences.
+
+@item !
+to replace all remaining occurrences without asking again.
+
+@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}.
+
+@item C-r
+to enter a recursive editing level, in case the occurrence needs to be
+edited rather than just replaced with @var{newstring}.  When you are
+done, exit the recursive editing level with @kbd{C-M-c} to proceed to
+the next occurrence.  @xref{Recursive Edit}.
+
+@item C-w
+to delete the occurrence, and then enter a recursive editing level as in
+@kbd{C-r}.  Use the recursive edit to insert text to replace the deleted
+occurrence of @var{string}.  When done, exit the recursive editing level
+with @kbd{C-M-c} to proceed to the next occurrence.
+
+@item C-l
+to redisplay the screen.  Then you must type another character to
+specify what to do with this occurrence.
+
+@item C-h
+to display a message summarizing these options.  Then you must type
+another character to specify what to do with this occurrence.
+@end table
+
+  Some other characters are aliases for the ones listed above: @kbd{y},
+@kbd{n} and @kbd{q} are equivalent to @key{SPC}, @key{DEL} and
+@key{RET}.
+
+  Aside from this, any other character exits the @code{query-replace},
+and is then reread as part of a key sequence.  Thus, if you type
+@kbd{C-k}, it exits the @code{query-replace} and then kills to end of
+line.
+
+  To restart a @code{query-replace} once it is exited, use @kbd{C-x
+@key{ESC} @key{ESC}}, which repeats the @code{query-replace} because it
+used the minibuffer to read its arguments.  @xref{Repetition, C-x ESC
+ESC}.
+
+  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
+@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}.
+
+@findex list-matching-lines
+@findex occur
+@findex count-matches
+@findex delete-non-matching-lines
+@findex delete-matching-lines
+@findex flush-lines
+@findex keep-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}).
+
+@kindex RET @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.
+
+@item M-x list-matching-lines
+Synonym for @kbd{M-x occur}.
+
+@item M-x count-matches @key{RET} @var{regexp} @key{RET}
+Print the number of matches for @var{regexp} after point.
+
+@item M-x flush-lines @key{RET} @var{regexp} @key{RET}
+Delete each line that follows point and contains a match for
+@var{regexp}.
+
+@item M-x keep-lines @key{RET} @var{regexp} @key{RET}
+Delete each line that follows point and @emph{does not} contain a match
+for @var{regexp}.
+@end table
+
+  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}.