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1327 lines
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1327 lines
57 KiB
Plaintext
@c This is part of the Emacs manual.
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@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001, 2002,
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@c 2003, 2004, 2005 Free Software Foundation, Inc.
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@c See file emacs.texi for copying conditions.
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@node Search, Fixit, Display, Top
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@chapter Searching and Replacement
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@cindex searching
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@cindex finding strings within text
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Like other editors, Emacs has commands for searching for occurrences of
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a string. The principal search command is unusual in that it is
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@dfn{incremental}; it begins to search before you have finished typing the
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search string. There are also nonincremental search commands more like
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those of other editors.
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Besides the usual @code{replace-string} command that finds all
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occurrences of one string and replaces them with another, Emacs has a
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more flexible replacement command called @code{query-replace}, which
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asks interactively which occurrences to replace.
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@menu
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* Incremental Search:: Search happens as you type the string.
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* Nonincremental Search:: Specify entire string and then search.
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* Word Search:: Search for sequence of words.
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* Regexp Search:: Search for match for a regexp.
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* Regexps:: Syntax of regular expressions.
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* Regexp Backslash:: Regular expression constructs starting with `\'.
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* Regexp Example:: A complex regular expression explained.
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* Search Case:: To ignore case while searching, or not.
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* Replace:: Search, and replace some or all matches.
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* Other Repeating Search:: Operating on all matches for some regexp.
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@end menu
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@node Incremental Search
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@section Incremental Search
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An incremental search begins searching as soon as you type the first
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character of the search string. As you type in the search string, Emacs
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shows you where the string (as you have typed it so far) would be
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found. When you have typed enough characters to identify the place you
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want, you can stop. Depending on what you plan to do next, you may or
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may not need to terminate the search explicitly with @key{RET}.
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@c WideCommands
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@table @kbd
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@item C-s
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Incremental search forward (@code{isearch-forward}).
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@item C-r
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Incremental search backward (@code{isearch-backward}).
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@end table
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@menu
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* Basic Isearch:: Basic incremental search commands.
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* Repeat Isearch:: Searching for the same string again.
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* Error in Isearch:: When your string is not found.
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* Special Isearch:: Special input in incremental search.
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* Non-ASCII Isearch:: How to search for non-ASCII characters.
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* Isearch Yank:: Commands that grab text into the search string
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or else edit the search string.
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* Highlight Isearch:: Isearch highlights the other possible matches.
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* Isearch Scroll:: Scrolling during an incremental search.
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* Slow Isearch:: Incremental search features for slow terminals.
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@end menu
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@node Basic Isearch
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@subsection Basics of Incremental Search
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@cindex incremental search
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@kindex C-s
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@findex isearch-forward
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@kbd{C-s} starts a forward incremental search. It reads characters
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from the keyboard, and moves point past the next occurrence of those
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characters. If you type @kbd{C-s} and then @kbd{F}, that puts the
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cursor after the first @samp{F} (the first following the starting point, since
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this is a forward search). Then if you type an @kbd{O}, you will see
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the cursor move just after the first @samp{FO} (the @samp{F} in that
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@samp{FO} may or may not be the first @samp{F}). After another
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@kbd{O}, the cursor moves after the first @samp{FOO} after the place
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where you started the search. At each step, the buffer text that
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matches the search string is highlighted, if the terminal can do that;
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the current search string is always displayed in the echo area.
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If you make a mistake in typing the search string, you can cancel
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characters with @key{DEL}. Each @key{DEL} cancels the last character of
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search string. This does not happen until Emacs is ready to read another
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input character; first it must either find, or fail to find, the character
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you want to erase. If you do not want to wait for this to happen, use
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@kbd{C-g} as described below.
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When you are satisfied with the place you have reached, you can type
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@key{RET}, which stops searching, leaving the cursor where the search
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brought it. Also, any command not specially meaningful in searches
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stops the searching and is then executed. Thus, typing @kbd{C-a}
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would exit the search and then move to the beginning of the line.
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@key{RET} is necessary only if the next command you want to type is a
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printing character, @key{DEL}, @key{RET}, or another character that is
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special within searches (@kbd{C-q}, @kbd{C-w}, @kbd{C-r}, @kbd{C-s},
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@kbd{C-y}, @kbd{M-y}, @kbd{M-r}, @kbd{M-c}, @kbd{M-e}, and some other
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meta-characters).
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When you exit the incremental search, it sets the mark where point
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@emph{was} before the search. That is convenient for moving back
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there. In Transient Mark mode, incremental search sets the mark
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without activating it, and does so only if the mark is not already
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active.
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@node Repeat Isearch
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@subsection Repeating Incremental Search
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Sometimes you search for @samp{FOO} and find one, but not the one you
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expected to find. There was a second @samp{FOO} that you forgot
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about, before the one you were aiming for. In this event, type
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another @kbd{C-s} to move to the next occurrence of the search string.
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You can repeat this any number of times. If you overshoot, you can
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cancel some @kbd{C-s} characters with @key{DEL}.
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After you exit a search, you can search for the same string again by
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typing just @kbd{C-s C-s}: the first @kbd{C-s} is the key that invokes
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incremental search, and the second @kbd{C-s} means ``search again.''
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If a search is failing and you ask to repeat it by typing another
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@kbd{C-s}, it starts again from the beginning of the buffer.
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Repeating a failing reverse search with @kbd{C-r} starts again from
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the end. This is called @dfn{wrapping around}, and @samp{Wrapped}
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appears in the search prompt once this has happened. If you keep on
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going past the original starting point of the search, it changes to
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@samp{Overwrapped}, which means that you are revisiting matches that
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you have already seen.
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To reuse earlier search strings, use the @dfn{search ring}. The
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commands @kbd{M-p} and @kbd{M-n} move through the ring to pick a search
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string to reuse. These commands leave the selected search ring element
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in the minibuffer, where you can edit it. To edit the current search
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string in the minibuffer without replacing it with items from the
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search ring, type @kbd{M-e}. Type @kbd{C-s} or @kbd{C-r}
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to terminate editing the string and search for it.
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You can change to searching backwards with @kbd{C-r}. If a search fails
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because the place you started was too late in the file, you should do this.
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Repeated @kbd{C-r} keeps looking for more occurrences backwards. A
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@kbd{C-s} starts going forwards again. @kbd{C-r} in a search can be canceled
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with @key{DEL}.
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@kindex C-r
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@findex isearch-backward
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If you know initially that you want to search backwards, you can use
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@kbd{C-r} instead of @kbd{C-s} to start the search, because @kbd{C-r} as
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a key runs a command (@code{isearch-backward}) to search backward. A
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backward search finds matches that are entirely before the starting
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point, just as a forward search finds matches that begin after it.
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@node Error in Isearch
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@subsection Errors in Incremental Search
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If your string is not found at all, the echo area says @samp{Failing
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I-Search}. The cursor is after the place where Emacs found as much of your
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string as it could. Thus, if you search for @samp{FOOT}, and there is no
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@samp{FOOT}, you might see the cursor after the @samp{FOO} in @samp{FOOL}.
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At this point there are several things you can do. If your string was
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mistyped, you can rub some of it out and correct it. If you like the place
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you have found, you can type @key{RET} or some other Emacs command to
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remain there. Or you can type @kbd{C-g}, which
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removes from the search string the characters that could not be found (the
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@samp{T} in @samp{FOOT}), leaving those that were found (the @samp{FOO} in
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@samp{FOOT}). A second @kbd{C-g} at that point cancels the search
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entirely, returning point to where it was when the search started.
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@cindex quitting (in search)
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The @kbd{C-g} ``quit'' character does special things during searches;
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just what it does depends on the status of the search. If the search has
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found what you specified and is waiting for input, @kbd{C-g} cancels the
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entire search. The cursor moves back to where you started the search. If
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@kbd{C-g} is typed when there are characters in the search string that have
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not been found---because Emacs is still searching for them, or because it
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has failed to find them---then the search string characters which have not
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been found are discarded from the search string. With them gone, the
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search is now successful and waiting for more input, so a second @kbd{C-g}
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will cancel the entire search.
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@node Special Isearch
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@subsection Special Input for Incremental Search
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An upper-case letter in the search string makes the search
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case-sensitive. If you delete the upper-case character from the search
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string, it ceases to have this effect. @xref{Search Case}.
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To search for a newline, type @kbd{C-j}. To search for another
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control character, such as control-S or carriage return, you must quote
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it by typing @kbd{C-q} first. This function of @kbd{C-q} is analogous
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to its use for insertion (@pxref{Inserting Text}): it causes the
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following character to be treated the way any ``ordinary'' character is
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treated in the same context. You can also specify a character by its
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octal code: enter @kbd{C-q} followed by a sequence of octal digits.
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@kbd{M-%} typed in incremental search invokes @code{query-replace}
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or @code{query-replace-regexp} (depending on search mode) with the
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current search string used as the string to replace. @xref{Query
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Replace}.
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Entering @key{RET} when the search string is empty launches
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nonincremental search (@pxref{Nonincremental Search}).
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@vindex isearch-mode-map
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To customize the special characters that incremental search understands,
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alter their bindings in the keymap @code{isearch-mode-map}. For a list
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of bindings, look at the documentation of @code{isearch-mode} with
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@kbd{C-h f isearch-mode @key{RET}}.
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@node Non-ASCII Isearch
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@subsection Isearch for Non-@acronym{ASCII} Characters
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@cindex searching for non-@acronym{ASCII} characters
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@cindex input method, during incremental search
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To enter non-@acronym{ASCII} characters in an incremental search,
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you must use an input method (@pxref{Input Methods}). If an input
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method is enabled in the current buffer when you start the search, you
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can use it while you type the search string also. Emacs indicates
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that by including the input method mnemonic in its prompt, like this:
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@example
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I-search [@var{im}]:
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@end example
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@noindent
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@findex isearch-toggle-input-method
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@findex isearch-toggle-specified-input-method
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where @var{im} is the mnemonic of the active input method. You can
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toggle (enable or disable) the input method while you type the search
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string with @kbd{C-\} (@code{isearch-toggle-input-method}). You can
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turn on a certain (non-default) input method with @kbd{C-^}
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(@code{isearch-toggle-specified-input-method}), which prompts for the
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name of the input method. The input method you enable during
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incremental search remains enabled in the current buffer afterwards.
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@node Isearch Yank
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@subsection Isearch Yanking
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The characters @kbd{C-w} and @kbd{C-y} can be used in incremental
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search to grab text from the buffer into the search string. This
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makes it convenient to search for another occurrence of text at point.
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@kbd{C-w} copies the character or word after point as part of the
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search string, advancing point over it. (The decision, whether to
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copy a character or a word, is heuristic.) Another @kbd{C-s} to
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repeat the search will then search for a string including that
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character or word.
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@kbd{C-y} is similar to @kbd{C-w} but copies all the rest of the
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current line into the search string. If point is already at the end
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of a line, it grabs the entire next line. Both @kbd{C-y} and
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@kbd{C-w} convert the text they copy to lower case if the search is
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currently not case-sensitive; this is so the search remains
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case-insensitive.
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@kbd{C-M-w} and @kbd{C-M-y} modify the search string by only one
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character at a time: @kbd{C-M-w} deletes the last character from the
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search string and @kbd{C-M-y} copies the character after point to the
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end of the search string. An alternative method to add the character
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after point into the search string is to enter the minibuffer by
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@kbd{M-e} and to type @kbd{C-f} at the end of the search string in the
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minibuffer.
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The character @kbd{M-y} copies text from the kill ring into the search
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string. It uses the same text that @kbd{C-y} as a command would yank.
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@kbd{Mouse-2} in the echo area does the same.
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@xref{Yanking}.
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@node Highlight Isearch
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@subsection Lazy Search Highlighting
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@cindex lazy search highlighting
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@vindex isearch-lazy-highlight
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When you pause for a little while during incremental search, it
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highlights all other possible matches for the search string. This
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makes it easier to anticipate where you can get to by typing @kbd{C-s}
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or @kbd{C-r} to repeat the search. The short delay before highlighting
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other matches helps indicate which match is the current one.
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If you don't like this feature, you can turn it off by setting
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@code{isearch-lazy-highlight} to @code{nil}.
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@cindex faces for highlighting search matches
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You can control how this highlighting looks by customizing the faces
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@code{isearch} (used for the current match) and @code{lazy-highlight}
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(for all the other matches). The latter is also used for other matches
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inside @code{query-replace}.
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@node Isearch Scroll
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@subsection Scrolling During Incremental Search
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Vertical scrolling during incremental search can be enabled by
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setting the customizable variable @code{isearch-allow-scroll} to a
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non-@code{nil} value.
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You can then use the vertical scroll-bar or certain keyboard
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commands such as @kbd{@key{PRIOR}} (@code{scroll-down}),
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@kbd{@key{NEXT}} (@code{scroll-up}) and @kbd{C-l} (@code{recenter})
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within the search, thus letting you see more of the text near the
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current match. You must run these commands via their key sequences to
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stay in the search---typing M-x @var{command-name} will always
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terminate a search.
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You can give prefix arguments to these commands in the usual way.
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The current match cannot be scrolled out of the window---this is
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intentional.
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Several other commands, such as @kbd{C-x 2}
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(@code{split-window-vertically}) and @kbd{C-x ^}
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(@code{enlarge-window}) which don't scroll the window, are
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nevertheless made available under this rubric, since they are likewise
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handy during a search.
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You can make other commands usable within an incremental search by
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giving the command a non-@code{nil} @code{isearch-scroll} property.
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For example, to make @kbd{C-h l} usable within an incremental search
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in all future Emacs sessions, use @kbd{C-h c} to find what command it
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runs. (You type @kbd{C-h c C-h l}; it says @code{view-lossage}.) Then
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you can put the following line in your @file{.emacs} file (@pxref{Init File}):
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@example
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(put 'view-lossage 'isearch-scroll t)
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@end example
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@noindent
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This works for commands that don't permanently change point, the
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buffer contents, the match data, the current buffer, or the selected
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window and frame. The command must not delete the current window and
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must not itself attempt an incremental search.
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@node Slow Isearch
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@subsection Slow Terminal Incremental Search
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Incremental search on a slow terminal uses a modified style of display
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that is designed to take less time. Instead of redisplaying the buffer at
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each place the search gets to, it creates a new single-line window and uses
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that to display the line that the search has found. The single-line window
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comes into play as soon as point moves outside of the text that is already
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on the screen.
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When you terminate the search, the single-line window is removed.
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Emacs then redisplays the window in which the search was done, to show
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its new position of point.
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@vindex search-slow-speed
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The slow terminal style of display is used when the terminal baud rate is
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less than or equal to the value of the variable @code{search-slow-speed},
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initially 1200. See also the discussion of the variable @code{baud-rate}
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(@pxref{baud-rate,, Customization of Display}).
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@vindex search-slow-window-lines
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The number of lines to use in slow terminal search display is controlled
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by the variable @code{search-slow-window-lines}. Its normal value is 1.
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@node Nonincremental Search
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@section Nonincremental Search
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@cindex nonincremental search
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Emacs also has conventional nonincremental search commands, which require
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you to type the entire search string before searching begins.
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@table @kbd
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@item C-s @key{RET} @var{string} @key{RET}
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Search for @var{string}.
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@item C-r @key{RET} @var{string} @key{RET}
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Search backward for @var{string}.
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@end table
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To do a nonincremental search, first type @kbd{C-s @key{RET}}. This
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enters the minibuffer to read the search string; terminate the string
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with @key{RET}, and then the search takes place. If the string is not
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found, the search command signals an error.
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When you type @kbd{C-s @key{RET}}, the @kbd{C-s} invokes incremental
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search as usual. That command is specially programmed to invoke
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nonincremental search, @code{search-forward}, if the string you
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specify is empty. (Such an empty argument would otherwise be
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useless.) But it does not call @code{search-forward} right away. First
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it checks the next input character to see if is @kbd{C-w},
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which specifies a word search.
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@ifinfo
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@xref{Word Search}.
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@end ifinfo
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@kbd{C-r @key{RET}} does likewise, for a reverse incremental search.
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@findex search-forward
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@findex search-backward
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Forward and backward nonincremental searches are implemented by the
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commands @code{search-forward} and @code{search-backward}. These
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commands may be bound to keys in the usual manner. The feature that you
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can get to them via the incremental search commands exists for
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historical reasons, and to avoid the need to find key sequences
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for them.
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@node Word Search
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@section Word Search
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@cindex word search
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Word search searches for a sequence of words without regard to how the
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words are separated. More precisely, you type a string of many words,
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using single spaces to separate them, and the string can be found even
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if there are multiple spaces, newlines, or other punctuation characters
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between these words.
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Word search is useful for editing a printed document made with a text
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formatter. If you edit while looking at the printed, formatted version,
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you can't tell where the line breaks are in the source file. With word
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search, you can search without having to know them.
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@table @kbd
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@item C-s @key{RET} C-w @var{words} @key{RET}
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Search for @var{words}, ignoring details of punctuation.
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@item C-r @key{RET} C-w @var{words} @key{RET}
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Search backward for @var{words}, ignoring details of punctuation.
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@end table
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Word search is a special case of nonincremental search and is invoked
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with @kbd{C-s @key{RET} C-w}. This is followed by the search string,
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which must always be terminated with @key{RET}. Being nonincremental,
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this search does not start until the argument is terminated. It works
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|
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. They are available
|
|
via the incremental search commands both for historical reasons and
|
|
to avoid the need to find suitable key sequences for them.
|
|
|
|
@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. 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}), 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
|
|
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}.
|
|
|
|
@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}}. You can control what a
|
|
bare spece matches by setting the variable
|
|
@code{search-whitespace-regexp} to the desired regexp.
|
|
|
|
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
|
|
@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.)
|
|
|
|
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 @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 @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
|
|
@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 @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 @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 @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, 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.
|
|
|
|
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 @acronym{ASCII} letter. Ranges may be
|
|
intermixed freely with individual characters, as in @samp{[a-z$%.]},
|
|
which matches any lower-case @acronym{ASCII} letter or @samp{$}, @samp{%} or
|
|
period.
|
|
|
|
Note that the usual regexp special characters are not special inside a
|
|
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. (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 @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} @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
|
|
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 @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.
|
|
|
|
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
|
|
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.
|
|
|
|
@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 \|
|
|
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 usually no conflict between the two meanings; when there is
|
|
a conflict, you can use a ``shy'' group.
|
|
|
|
@item \(?: @dots{} \)
|
|
@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 were written by the user.
|
|
|
|
@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 string or
|
|
buffer (or its accessible portion) being matched against.
|
|
|
|
@item \'
|
|
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 \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 \_<
|
|
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}
|
|
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}.
|
|
|
|
@cindex categories of characters
|
|
@cindex characters which belong to a specific language
|
|
@findex describe-categories
|
|
@item \c@var{c}
|
|
matches any character that belongs to the category @var{c}. For
|
|
example, @samp{\cc} matches Chinese characters, @samp{\cg} matches
|
|
Greek characters, etc. For the description of the known categories,
|
|
type @kbd{M-x describe-categories @key{RET}}.
|
|
|
|
@item \C@var{c}
|
|
matches any character that does @emph{not} belong to category
|
|
@var{c}.
|
|
@end table
|
|
|
|
The constructs that pertain to words and syntax are controlled by the
|
|
setting of the syntax table (@pxref{Syntax}).
|
|
|
|
@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]*"
|
|
@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 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
|
|
|
|
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.
|
|
|
|
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 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 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 (@pxref{Transient
|
|
Mark}), 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
|
|
|
|
@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}.
|
|
@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.
|
|
|
|
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.
|
|
|
|
@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
|
|
|
|
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}. @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
|
|
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. 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
|
|
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.
|
|
|
|
@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. 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
|
|
@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:
|
|
|
|
@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 or want to
|
|
reexamine it.
|
|
|
|
@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 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 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
|
|
@section Other Search-and-Loop Commands
|
|
|
|
Here are some other commands that find matches for a regular
|
|
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-by-filename-regexp
|
|
@findex how-many
|
|
@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}. 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.
|
|
@kbd{o} and @kbd{C-o} display the match in another window; @kbd{C-o}
|
|
does not select it.
|
|
|
|
Occur mode supports the @code{next-error} functionality described in
|
|
@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.
|
|
|
|
@item M-x multi-occur-by-filename-regexp @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.
|
|
|
|
@item M-x how-many @key{RET} @var{regexp} @key{RET}
|
|
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}
|
|
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}
|
|
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 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
|