-This is ../info/xemacs.info, produced by makeinfo version 3.12s from
+This is ../info/xemacs.info, produced by makeinfo version 4.0b from
xemacs/xemacs.texi.
INFO-DIR-SECTION XEmacs Editor
translation approved by the author instead of in the original English.
\1f
-File: xemacs.info, Node: Backup Copying, Prev: Backup Deletion, Up: Backup
-
-Copying vs. Renaming
-....................
-
- You can make backup files by copying the old file or by renaming it.
-This makes a difference when the old file has multiple names. If you
-rename the old file into the backup file, the alternate names become
-names for the backup file. If you copy the old file instead, the
-alternate names remain names for the file that you are editing, and the
-contents accessed by those names will be the new contents.
-
- How you make a backup file may also affect the file's owner and
-group. If you use copying, they do not change. If renaming is used,
-you become the file's owner, and the file's group becomes the default
-(different operating systems have different defaults for the group).
-
- Having the owner change is usually a good idea, because then the
-owner is always the person who last edited the file. Occasionally
-there is a file whose owner should not change. Since most files should
-change owners, it is a good idea to use local variable lists to set
-`backup-by-copying-when-mismatch' for the special cases where the owner
-should not change (*note File Variables::).
-
- Three variables control the choice of renaming or copying.
-Normally, renaming is done. If the variable `backup-by-copying' is
-non-`nil', copying is used. Otherwise, if the variable
-`backup-by-copying-when-linked' is non-`nil', copying is done for files
-that have multiple names, but renaming may still be done when the file
-being edited has only one name. If the variable
-`backup-by-copying-when-mismatch' is non-`nil', copying is done if
-renaming would cause the file's owner or group to change.
+File: xemacs.info, Node: Regexps, Next: Search Case, Prev: Regexp Search, Up: Search
-\1f
-File: xemacs.info, Node: Interlocking, Prev: Backup, Up: Saving
-
-Protection Against Simultaneous Editing
----------------------------------------
-
- Simultaneous editing occurs when two users visit the same file, both
-make changes, and both save their changes. If no one was informed that
-this was happening, and you saved first, you would later find that your
-changes were lost. On some systems, Emacs notices immediately when the
-second user starts to change a file already being edited, and issues a
-warning. When this is not possible, or if the second user has started
-to change the file despite the warning, Emacs checks when the file is
-saved, and issues a second warning when a user is about to overwrite a
-file containing another user's changes. If you are the user editing the
-file, you can take corrective action at this point and prevent actual
-loss of work.
-
- When you make the first modification in an Emacs buffer that is
-visiting a file, Emacs records that you have locked the file. (It does
-this by writing another file in a directory reserved for this purpose.)
-The lock is removed when you save the changes. The idea is that the
-file is locked whenever the buffer is modified. If you begin to modify
-the buffer while the visited file is locked by someone else, this
-constitutes a collision, and Emacs asks you what to do. It does this
-by calling the Lisp function `ask-user-about-lock', which you can
-redefine to customize what it does. The standard definition of this
-function asks you a question and accepts three possible answers:
-
-`s'
- Steal the lock. Whoever was already changing the file loses the
- lock, and you get the lock.
-
-`p'
- Proceed. Go ahead and edit the file despite its being locked by
- someone else.
-
-`q'
- Quit. This causes an error (`file-locked') and the modification
- you were trying to make in the buffer does not actually take place.
-
- Note that locking works on the basis of a file name; if a file has
-multiple names, Emacs does not realize that the two names are the same
-file and cannot prevent two users from editing it simultaneously under
-different names. However, basing locking on names means that Emacs can
-interlock the editing of new files that do not really exist until they
-are saved.
-
- Some systems are not configured to allow Emacs to make locks. On
-these systems, Emacs cannot detect trouble in advance, but it can still
-detect it in time to prevent you from overwriting someone else's
-changes.
-
- Every time Emacs saves a buffer, it first checks the
-last-modification date of the existing file on disk to see that it has
-not changed since the file was last visited or saved. If the date does
-not match, it implies that changes were made in the file in some other
-way, and these changes are about to be lost if Emacs actually does
-save. To prevent this, Emacs prints a warning message and asks for
-confirmation before saving. Occasionally you will know why the file
-was changed and know that it does not matter; then you can answer `yes'
-and proceed. Otherwise, you should cancel the save with `C-g' and
-investigate the situation.
-
- The first thing you should do when notified that simultaneous editing
-has already taken place is to list the directory with `C-u C-x C-d'
-(*note Directory Listing: ListDir.). This will show the file's current
-author. You should attempt to contact that person and ask him not to
-continue editing. Often the next step is to save the contents of your
-Emacs buffer under a different name, and use `diff' to compare the two
-files.
-
- Simultaneous editing checks are also made when you visit a file that
-is already visited with `C-x C-f' and when you start to modify a file.
-This is not strictly necessary, but it is useful to find out about such
-a problem as early as possible, when corrective action takes less work.
-
- Another way to protect your file is to set the read, write, and
-executable permissions for the file. Use the function
-`set-default-file-modes' to set the UNIX `umask' value to the NMASK
-argument. The `umask' value is the default protection mode for new
-files.
+Syntax of Regular Expressions
+=============================
-\1f
-File: xemacs.info, Node: Reverting, Next: Auto Save, Prev: Saving, Up: Files
+ Regular expressions have a syntax in which a few characters are
+special constructs and the rest are "ordinary". An ordinary character
+is a simple regular expression that matches that character and nothing
+else. The special characters are `.', `*', `+', `?', `[', `]', `^',
+`$', and `\'; no new special characters will be defined in the future.
+Any other character appearing in a regular expression is ordinary,
+unless a `\' precedes it.
-Reverting a Buffer
-==================
+ For example, `f' is not a special character, so it is ordinary, and
+therefore `f' is a regular expression that matches the string `f' and
+no other string. (It does _not_ match the string `ff'.) Likewise, `o'
+is a regular expression that matches only `o'.
- If you have made extensive changes to a file and then change your
-mind about them, you can get rid of all changes by reading in the
-previous version of the file. To do this, use `M-x revert-buffer',
-which operates on the current buffer. Since reverting a buffer can
-result in very extensive changes, you must confirm it with `yes'.
-
- If the current buffer has been auto-saved more recently than it has
-been saved explicitly, `revert-buffer' offers to read the auto save file
-instead of the visited file (*note Auto Save::). Emacs asks you about
-the auto-save file before the request for confirmation of the
-`revert-buffer' operation, and demands `y' or `n' as an answer. If you
-have started to type `yes' for confirmation without realizing that the
-auto-save question was going to be asked, the `y' will answer that
-question, but the `es' will not be valid confirmation. This gives you
-a chance to cancel the operation with `C-g' and try again with the
-answers you really intend.
-
- `revert-buffer' keeps point at the same distance (measured in
-characters) from the beginning of the file. If the file was edited only
-slightly, you will be at approximately the same piece of text after
-reverting as before. If you have made more extensive changes, the
-value of point in the old file may bring you to a totally different
-piece of text than your last editing point.
-
- A buffer reverted from its visited file is marked "not modified"
-until you make a change.
-
- Some kinds of buffers whose contents reflect data bases other than
-files, such as Dired buffers, can also be reverted. For them,
-reverting means recalculating their contents from the appropriate data.
-Buffers created randomly with `C-x b' cannot be reverted;
-`revert-buffer' reports an error when asked to do so.
+ Any two regular expressions A and B can be concatenated. The result
+is a regular expression that matches a string if A matches some amount
+of the beginning of that string and B matches the rest of the string.
-\1f
-File: xemacs.info, Node: Auto Save, Next: Version Control, Prev: Reverting, Up: Files
+ As a simple example, we can concatenate the regular expressions `f'
+and `o' to get the regular expression `fo', which matches only the
+string `fo'. Still trivial. To do something more powerful, you need
+to use one of the special characters. Here is a list of them:
-Auto-Saving: Protection Against Disasters
-=========================================
-
- Emacs saves all the visited files from time to time (based on
-counting your keystrokes) without being asked. This is called
-"auto-saving". It prevents you from losing more than a limited amount
-of work if the system crashes.
-
- When Emacs determines it is time for auto-saving, each buffer is
-considered and is auto-saved if auto-saving is turned on for it and it
-has changed since the last time it was auto-saved. If any auto-saving
-is done, the message `Auto-saving...' is displayed in the echo area
-until auto-saving is finished. Errors occurring during auto-saving are
-caught so that they do not interfere with the execution of commands you
-have been typing.
+`. (Period)'
+ is a special character that matches any single character except a
+ newline. Using concatenation, we can make regular expressions
+ like `a.b', which matches any three-character string that begins
+ with `a' and ends with `b'.
+
+`*'
+ is not a construct by itself; it is a quantifying suffix operator
+ that means to repeat the preceding regular expression as many
+ times as possible. In `fo*', the `*' applies to the `o', so `fo*'
+ matches one `f' followed by any number of `o's. The case of zero
+ `o's is allowed: `fo*' does match `f'.
+
+ `*' always applies to the _smallest_ possible preceding
+ expression. Thus, `fo*' has a repeating `o', not a repeating `fo'.
+
+ The matcher processes a `*' construct by matching, immediately, as
+ many repetitions as can be found; it is "greedy". Then it
+ continues with the rest of the pattern. If that fails,
+ backtracking occurs, discarding some of the matches of the
+ `*'-modified construct in case that makes it possible to match the
+ rest of the pattern. For example, in matching `ca*ar' against the
+ string `caaar', the `a*' first tries to match all three `a's; but
+ the rest of the pattern is `ar' and there is only `r' left to
+ match, so this try fails. The next alternative is for `a*' to
+ match only two `a's. With this choice, the rest of the regexp
+ matches successfully.
+
+ Nested repetition operators can be extremely slow if they specify
+ backtracking loops. For example, it could take hours for the
+ regular expression `\(x+y*\)*a' to match the sequence
+ `xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxz'. The slowness is because
+ Emacs must try each imaginable way of grouping the 35 `x''s before
+ concluding that none of them can work. To make sure your regular
+ expressions run fast, check nested repetitions carefully.
+
+`+'
+ is a quantifying suffix operator similar to `*' except that the
+ preceding expression must match at least once. It is also
+ "greedy". So, for example, `ca+r' matches the strings `car' and
+ `caaaar' but not the string `cr', whereas `ca*r' matches all three
+ strings.
+
+`?'
+ is a quantifying suffix operator similar to `*', except that the
+ preceding expression can match either once or not at all. For
+ example, `ca?r' matches `car' or `cr', but does not match anything
+ else.
+
+`*?'
+ works just like `*', except that rather than matching the longest
+ match, it matches the shortest match. `*?' is known as a
+ "non-greedy" quantifier, a regexp construct borrowed from Perl.
+
+ This construct is very useful for when you want to match the text
+ inside a pair of delimiters. For instance, `/\*.*?\*/' will match
+ C comments in a string. This could not easily be achieved without
+ the use of a non-greedy quantifier.
+
+ This construct has not been available prior to XEmacs 20.4. It is
+ not available in FSF Emacs.
+
+`+?'
+ is the non-greedy version of `+'.
+
+`??'
+ is the non-greedy version of `?'.
+
+`\{n,m\}'
+ serves as an interval quantifier, analogous to `*' or `+', but
+ specifies that the expression must match at least N times, but no
+ more than M times. This syntax is supported by most Unix regexp
+ utilities, and has been introduced to XEmacs for the version 20.3.
+
+ Unfortunately, the non-greedy version of this quantifier does not
+ exist currently, although it does in Perl.
+
+`[ ... ]'
+ `[' begins a "character set", which is terminated by a `]'. In
+ the simplest case, the characters between the two brackets form
+ the set. Thus, `[ad]' matches either one `a' or one `d', and
+ `[ad]*' matches any string composed of just `a's and `d's
+ (including the empty string), from which it follows that `c[ad]*r'
+ matches `cr', `car', `cdr', `caddaar', etc.
+
+ The usual regular expression special characters are not special
+ inside a character set. A completely different set of special
+ characters exists inside character sets: `]', `-' and `^'.
+
+ `-' is used for ranges of characters. To write a range, write two
+ characters with a `-' between them. Thus, `[a-z]' matches any
+ lower case letter. Ranges may be intermixed freely with individual
+ characters, as in `[a-z$%.]', which matches any lower case letter
+ or `$', `%', or a period.
+
+ To include a `]' in a character set, make it the first character.
+ For example, `[]a]' matches `]' or `a'. To include a `-', write
+ `-' as the first character in the set, or put it immediately after
+ a range. (You can replace one individual character C with the
+ range `C-C' to make a place to put the `-'.) There is no way to
+ write a set containing just `-' and `]'.
+
+ To include `^' in a set, put it anywhere but at the beginning of
+ the set.
+
+`[^ ... ]'
+ `[^' begins a "complement character set", which matches any
+ character except the ones specified. Thus, `[^a-z0-9A-Z]' matches
+ all characters _except_ letters and digits.
+
+ `^' is not special in a character set unless it is the first
+ character. The character following the `^' is treated as if it
+ were first (thus, `-' and `]' are not special there).
+
+ Note that a complement character set can match a newline, unless
+ newline is mentioned as one of the characters not to match.
+
+`^'
+ is a special character that matches the empty string, but only at
+ the beginning of a line in the text being matched. Otherwise it
+ fails to match anything. Thus, `^foo' matches a `foo' that occurs
+ at the beginning of a line.
+
+ When matching a string instead of a buffer, `^' matches at the
+ beginning of the string or after a newline character `\n'.
+
+`$'
+ is similar to `^' but matches only at the end of a line. Thus,
+ `x+$' matches a string of one `x' or more at the end of a line.
+
+ When matching a string instead of a buffer, `$' matches at the end
+ of the string or before a newline character `\n'.
+
+`\'
+ has two functions: it quotes the special characters (including
+ `\'), and it introduces additional special constructs.
+
+ Because `\' quotes special characters, `\$' is a regular
+ expression that matches only `$', and `\[' is a regular expression
+ that matches only `[', and so on.
+
+ *Please note:* For historical compatibility, special characters are
+treated as ordinary ones if they are in contexts where their special
+meanings make no sense. For example, `*foo' treats `*' as ordinary
+since there is no preceding expression on which the `*' can act. It is
+poor practice to depend on this behavior; quote the special character
+anyway, regardless of where it appears.
+
+ For the most part, `\' followed by any character matches only that
+character. However, there are several exceptions: characters that,
+when preceded by `\', are special constructs. Such characters are
+always ordinary when encountered on their own. Here is a table of `\'
+constructs:
+
+`\|'
+ specifies an alternative. Two regular expressions A and B with
+ `\|' in between form an expression that matches anything that
+ either A or B matches.
+
+ Thus, `foo\|bar' matches either `foo' or `bar' but no other string.
+
+ `\|' applies to the largest possible surrounding expressions.
+ Only a surrounding `\( ... \)' grouping can limit the grouping
+ power of `\|'.
+
+ Full backtracking capability exists to handle multiple uses of
+ `\|'.
+
+`\( ... \)'
+ is a grouping construct that serves three purposes:
+
+ 1. To enclose a set of `\|' alternatives for other operations.
+ Thus, `\(foo\|bar\)x' matches either `foox' or `barx'.
+
+ 2. To enclose an expression for a suffix operator such as `*' to
+ act on. Thus, `ba\(na\)*' matches `bananana', etc., with any
+ (zero or more) number of `na' strings.
+
+ 3. To record a matched substring for future reference.
+
+ This last application is not a consequence of the idea of a
+ parenthetical grouping; it is a separate feature that happens to be
+ assigned as a second meaning to the same `\( ... \)' construct
+ because there is no conflict in practice between the two meanings.
+ Here is an explanation of this feature:
+
+`\DIGIT'
+ matches the same text that matched the DIGITth occurrence of a `\(
+ ... \)' construct.
+
+ In other words, after the end of a `\( ... \)' construct. the
+ matcher remembers the beginning and end of the text matched by that
+ construct. Then, later on in the regular expression, you can use
+ `\' followed by DIGIT to match that same text, whatever it may
+ have been.
+
+ The strings matching the first nine `\( ... \)' constructs
+ appearing in a regular expression are assigned numbers 1 through 9
+ in the order that the open parentheses appear in the regular
+ expression. So you can use `\1' through `\9' to refer to the text
+ matched by the corresponding `\( ... \)' constructs.
+
+ For example, `\(.*\)\1' matches any newline-free string that is
+ composed of two identical halves. The `\(.*\)' matches the first
+ half, which may be anything, but the `\1' that follows must match
+ the same exact text.
+
+`\(?: ... \)'
+ is called a "shy" grouping operator, and it is used just like `\(
+ ... \)', except that it does not cause the matched substring to be
+ recorded for future reference.
+
+ This is useful when you need a lot of grouping `\( ... \)'
+ constructs, but only want to remember one or two - or if you have
+ more than nine groupings and need to use backreferences to refer to
+ the groupings at the end.
+
+ Using `\(?: ... \)' rather than `\( ... \)' when you don't need
+ the captured substrings ought to speed up your programs some,
+ since it shortens the code path followed by the regular expression
+ engine, as well as the amount of memory allocation and string
+ copying it must do. The actual performance gain to be observed
+ has not been measured or quantified as of this writing.
+
+ The shy grouping operator has been borrowed from Perl, and has not
+ been available prior to XEmacs 20.3, nor is it available in FSF
+ Emacs.
+
+`\w'
+ matches any word-constituent character. The editor syntax table
+ determines which characters these are. *Note Syntax::.
+
+`\W'
+ matches any character that is not a word constituent.
+
+`\sCODE'
+ matches any character whose syntax is CODE. Here CODE is a
+ character that represents a syntax code: thus, `w' for word
+ constituent, `-' for whitespace, `(' for open parenthesis, etc.
+ *Note Syntax::, for a list of syntax codes and the characters that
+ stand for them.
+
+`\SCODE'
+ matches any character whose syntax is not CODE.
+
+ The following regular expression constructs match the empty
+string--that is, they don't use up any characters--but whether they
+match depends on the context.
+
+`\`'
+ matches the empty string, but only at the beginning of the buffer
+ or string being matched against.
+
+`\''
+ matches the empty string, but only at the end of the buffer or
+ string being matched against.
+
+`\='
+ matches the empty string, but only at point. (This construct is
+ not defined when matching against a string.)
+
+`\b'
+ matches the empty string, but only at the beginning or end of a
+ word. Thus, `\bfoo\b' matches any occurrence of `foo' as a
+ separate word. `\bballs?\b' matches `ball' or `balls' as a
+ separate word.
+
+`\B'
+ matches the empty string, but _not_ at the beginning or end of a
+ word.
+
+`\<'
+ matches the empty string, but only at the beginning of a word.
+
+`\>'
+ matches the empty string, but only at the end of a word.
+
+ Here is a complicated regexp used by Emacs to recognize the end of a
+sentence together with any whitespace that follows. It is given in Lisp
+syntax to enable you to distinguish the spaces from the tab characters.
+In Lisp syntax, the string constant begins and ends with a
+double-quote. `\"' stands for a double-quote as part of the regexp,
+`\\' for a backslash as part of the regexp, `\t' for a tab and `\n' for
+a newline.
+
+ "[.?!][]\"')]*\\($\\|\t\\| \\)[ \t\n]*"
+
+This regexp contains four parts: a character set matching period, `?'
+or `!'; a character set matching close-brackets, quotes or parentheses,
+repeated any number of times; an alternative in backslash-parentheses
+that matches end-of-line, a tab or two spaces; and a character set
+matching whitespace characters, repeated any number of times.
-* Menu:
+\1f
+File: xemacs.info, Node: Search Case, Next: Replace, Prev: Regexps, Up: Search
-* Files: Auto Save Files.
-* Control: Auto Save Control.
-* Recover:: Recovering text from auto-save files.
+Searching and Case
+==================
-\1f
-File: xemacs.info, Node: Auto Save Files, Next: Auto Save Control, Prev: Auto Save, Up: Auto Save
-
-Auto-Save Files
----------------
-
- Auto-saving does not normally write to the files you visited, because
-it can be undesirable to save a program that is in an inconsistent
-state when you have made only half of a planned change. Instead,
-auto-saving is done in a different file called the "auto-save file",
-and the visited file is changed only when you save explicitly, for
-example, with `C-x C-s'.
-
- Normally, the name of the auto-save file is generated by appending
-`#' to the front and back of the visited file name. Thus, a buffer
-visiting file `foo.c' would be auto-saved in a file `#foo.c#'. Most
-buffers that are not visiting files are auto-saved only if you request
-it explicitly; when they are auto-saved, the auto-save file name is
-generated by appending `#%' to the front and `#' to the back of buffer
-name. For example, the `*mail*' buffer in which you compose messages
-to be sent is auto-saved in a file named `#%*mail*#'. Names of
-auto-save files are generated this way unless you customize the
-functions `make-auto-save-file-name' and `auto-save-file-name-p' to do
-something different. The file name to be used for auto-saving a buffer
-is calculated at the time auto-saving is turned on in that buffer.
-
- If you want auto-saving to be done in the visited file, set the
-variable `auto-save-visited-file-name' to be non-`nil'. In this mode,
-there is really no difference between auto-saving and explicit saving.
-
- Emacs deletes a buffer's auto-save file when you explicitly save the
-buffer. To inhibit the deletion, set the variable
-`delete-auto-save-files' to `nil'. Changing the visited file name with
-`C-x C-w' or `set-visited-file-name' renames any auto-save file to
-correspond to the new visited name.
+ All searches in Emacs normally ignore the case of the text they are
+searching through; if you specify searching for `FOO', `Foo' and `foo'
+are also considered a match. Regexps, and in particular character
+sets, are included: `[aB]' matches `a' or `A' or `b' or `B'.
-\1f
-File: xemacs.info, Node: Auto Save Control, Next: Recover, Prev: Auto Save Files, Up: Auto Save
-
-Controlling Auto-Saving
------------------------
-
- Each time you visit a file, auto-saving is turned on for that file's
-buffer if the variable `auto-save-default' is non-`nil' (but not in
-batch mode; *note Entering Emacs::). The default for this variable is
-`t', so Emacs auto-saves buffers that visit files by default. You can
-use the command `M-x auto-save-mode' to turn auto-saving for a buffer
-on or off. Like other minor mode commands, `M-x auto-save-mode' turns
-auto-saving on with a positive argument, off with a zero or negative
-argument; with no argument, it toggles.
-
- Emacs performs auto-saving periodically based on counting how many
-characters you have typed since the last time auto-saving happened. The
-variable `auto-save-interval' specifies the number of characters
-between auto-saves. By default, it is 300. Emacs also auto-saves
-whenever you call the function `do-auto-save'.
-
- Emacs also does auto-saving whenever it gets a fatal error. This
-includes killing the Emacs job with a shell command such as `kill
--emacs', or disconnecting a phone line or network connection.
-
- You can set the number of seconds of idle time before an auto-save is
-done. Setting the value of the variable `auto-save-timeout' to zero or
-`nil' will disable auto-saving due to idleness.
-
- The actual amount of idle time between auto-saves is logarithmically
-related to the size of the current buffer. This variable is the number
-of seconds after which an auto-save will happen when the current buffer
-is 50k or less; the timeout will be 2 1/4 times this in a 200k buffer, 3
-3/4 times this in a 1000k buffer, and 4 1/2 times this in a 2000k
-buffer.
-
- For this variable to have any effect, you must do `(require 'timer)'.
+ If you want a case-sensitive search, set the variable
+`case-fold-search' to `nil'. Then all letters must match exactly,
+including case. `case-fold-search' is a per-buffer variable; altering
+it affects only the current buffer, but there is a default value which
+you can change as well. *Note Locals::. You can also use Case
+Sensitive Search from the Options menu on your screen.
\1f
-File: xemacs.info, Node: Recover, Prev: Auto Save Control, Up: Auto Save
+File: xemacs.info, Node: Replace, Next: Other Repeating Search, Prev: Search Case, Up: Search
-Recovering Data from Auto-Saves
--------------------------------
+Replacement Commands
+====================
- If you want to use the contents of an auto-save file to recover from
-a loss of data, use the command `M-x recover-file <RET> FILE <RET>'.
-Emacs visits FILE and then (after your confirmation) restores the
-contents from the auto-save file `#FILE#'. You can then save the file
-with `C-x C-s' to put the recovered text into FILE itself. For
-example, to recover file `foo.c' from its auto-save file `#foo.c#', do:
+ Global search-and-replace operations are not needed as often in
+Emacs as they are in other editors, but they are available. In
+addition to the simple `replace-string' command which is like that
+found in most editors, there is a `query-replace' command which asks
+you, for each occurrence of a pattern, whether to replace it.
- M-x recover-file <RET> foo.c <RET>
- C-x C-s
+ The replace commands all replace one string (or regexp) with one
+replacement string. It is possible to perform several replacements in
+parallel using the command `expand-region-abbrevs'. *Note Expanding
+Abbrevs::.
- Before asking for confirmation, `M-x recover-file' displays a
-directory listing describing the specified file and the auto-save file,
-so you can compare their sizes and dates. If the auto-save file is
-older, `M-x recover-file' does not offer to read it.
+* Menu:
- Auto-saving is disabled by `M-x recover-file' because using this
-command implies that the auto-save file contains valuable data from a
-past session. If you save the data in the visited file and then go on
-to make new changes, turn auto-saving back on with `M-x auto-save-mode'.
+* 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.
\1f
-File: xemacs.info, Node: Version Control, Next: ListDir, Prev: Auto Save, Up: Files
+File: xemacs.info, Node: Unconditional Replace, Next: Regexp Replace, Prev: Replace, Up: Replace
-Version Control
-===============
+Unconditional Replacement
+-------------------------
- "Version control systems" are packages that can record multiple
-versions of a source file, usually storing the unchanged parts of the
-file just once. Version control systems also record history information
-such as the creation time of each version, who created it, and a
-description of what was changed in that version.
+`M-x replace-string <RET> STRING <RET> NEWSTRING <RET>'
+ Replace every occurrence of STRING with NEWSTRING.
- The GNU project recommends the version control system known as RCS,
-which is free software and available from the Free Software Foundation.
-Emacs supports use of either RCS or SCCS (a proprietary, but widely
-used, version control system that is not quite as powerful as RCS)
-through a facility called VC. The same Emacs commands work with either
-RCS or SCCS, so you hardly have to know which one of them you are using.
+`M-x replace-regexp <RET> REGEXP <RET> NEWSTRING <RET>'
+ Replace every match for REGEXP with NEWSTRING.
-* Menu:
+ To replace every instance of `foo' after point with `bar', use the
+command `M-x replace-string' with the two arguments `foo' and `bar'.
+Replacement occurs only after point: if you want to cover the whole
+buffer you must go to the beginning first. By default, all occurrences
+up to the end of the buffer are replaced. To limit replacement to part
+of the buffer, narrow to that part of the buffer before doing the
+replacement (*note Narrowing::).
-* Concepts of VC:: Basic version control information;
- checking files in and out.
-* Editing with VC:: Commands for editing a file maintained
- with version control.
-* Variables for Check-in/out:: Variables that affect the commands used
- to check files in or out.
-* Log Entries:: Logging your changes.
-* Change Logs and VC:: Generating a change log file from log
- entries.
-* Old Versions:: Examining and comparing old versions.
-* VC Status:: Commands to view the VC status of files and
- look at log entries.
-* Renaming and VC:: A command to rename both the source and
- master file correctly.
-* Snapshots:: How to make and use snapshots, a set of
- file versions that can be treated as a unit.
-* Version Headers:: Inserting version control headers into
- working files.
+ When `replace-string' exits, point is left at the last occurrence
+replaced. The value of point when the `replace-string' command was
+issued is remembered on the mark ring; `C-u C-<SPC>' moves back there.
-\1f
-File: xemacs.info, Node: Concepts of VC, Next: Editing with VC, Prev: Version Control, Up: Version Control
+ A numeric argument restricts replacement to matches that are
+surrounded by word boundaries.
-Concepts of Version Control
----------------------------
+\1f
+File: xemacs.info, Node: Regexp Replace, Next: Replacement and Case, Prev: Unconditional Replace, Up: Replace
- When a file is under version control, we also say that it is
-"registered" in the version control system. Each registered file has a
-corresponding "master file" which represents the file's present state
-plus its change history, so that you can reconstruct from it either the
-current version or any specified earlier version. Usually the master
-file also records a "log entry" for each version describing what was
-changed in that version.
+Regexp Replacement
+------------------
- The file that is maintained under version control is sometimes called
-the "work file" corresponding to its master file.
+ `replace-string' replaces exact matches for a single string. The
+similar command `replace-regexp' replaces any match for a specified
+pattern.
- To examine a file, you "check it out". This extracts a version of
-the source file (typically, the most recent) from the master file. If
-you want to edit the file, you must check it out "locked". Only one
-user can do this at a time for any given source file. (This kind of
-locking is completely unrelated to the locking that Emacs uses to
-detect simultaneous editing of a file.)
+ In `replace-regexp', the NEWSTRING need not be constant. It can
+refer to all or part of what is matched by the REGEXP. `\&' in
+NEWSTRING stands for the entire text being replaced. `\D' in
+NEWSTRING, where D is a digit, stands for whatever matched the D'th
+parenthesized grouping in REGEXP. For example,
- When you are done with your editing, you must "check in" the new
-version. This records the new version in the master file, and unlocks
-the source file so that other people can lock it and thus modify it.
+ M-x replace-regexp <RET> c[ad]+r <RET> \&-safe <RET>
- Checkin and checkout are the basic operations of version control.
-You can do both of them with a single Emacs command: `C-x C-q'
-(`vc-toggle-read-only').
+would replace (for example) `cadr' with `cadr-safe' and `cddr' with
+`cddr-safe'.
- A "snapshot" is a coherent collection of versions of the various
-files that make up a program. *Note Snapshots::.
+ M-x replace-regexp <RET> \(c[ad]+r\)-safe <RET> \1 <RET>
-\1f
-File: xemacs.info, Node: Editing with VC, Next: Variables for Check-in/out, Prev: Concepts of VC, Up: Version Control
-
-Editing with Version Control
-----------------------------
-
- When you visit a file that is maintained using version control, the
-mode line displays `RCS' or `SCCS' to inform you that version control
-is in use, and also (in case you care) which low-level system the file
-is actually stored in. Normally, such a source file is read-only, and
-the mode line indicates this with `%%'. With RCS, the mode line also
-indicates the number of the head version, which is normally also the
-version you are looking at.
-
- These are the commands for editing a file maintained with version
-control:
-
-`C-x C-q'
- Check the visited file in or out.
-
-`C-x v u'
- Revert the buffer and the file to the last checked in version.
-
-`C-x v c'
- Remove the last-entered change from the master for the visited
- file. This undoes your last check-in.
-
-`C-x v i'
- Register the visited file in version control.
-
-(`C-x v' is the prefix key for version control commands; all of these
-commands except for `C-x C-q' start with `C-x v'.)
-
- When you want to modify a file maintained with version control, type
-`C-x C-q' (`vc-toggle-read-only'). This "checks out" the file, and
-tells RCS or SCCS to lock the file. This means making the file
-writable for you (but not for anyone else).
-
- When you are finished editing the file, type `C-x C-q' again. When
-used on a file that is checked out, this command checks the file in.
-But check-in does not start immediately; first, you must enter the "log
-entry"--a description of the changes in the new version. `C-x C-q'
-pops up a buffer for you to enter this in. When you are finished
-typing in the log entry, type `C-c C-c' to terminate it; this is when
-actual check-in takes place.
-
- Once you have checked in your changes, the file is unlocked, so that
-other users can lock it and modify it.
-
- Emacs does not save backup files for source files that are maintained
-with version control. If you want to make backup files despite version
-control, set the variable `vc-make-backup-files' to a non-`nil' value.
-
- Normally the work file exists all the time, whether it is locked or
-not. If you set `vc-keep-workfiles' to `nil', then checking in a new
-version with `C-x C-q' deletes the work file; but any attempt to visit
-the file with Emacs creates it again.
-
- It is not impossible to lock a file that someone else has locked. If
-you try to check out a file that is locked, `C-x C-q' asks you whether
-you want to "steal the lock." If you say yes, the file becomes locked
-by you, but a message is sent to the person who had formerly locked the
-file, to inform him of what has happened. The mode line indicates that
-a file is locked by someone else by displaying the login name of that
-person, before the version number.
-
- If you want to discard your current set of changes and revert to the
-last version checked in, use `C-x v u' (`vc-revert-buffer'). This
-cancels your last check-out, leaving the file unlocked. If you want to
-make a different set of changes, you must first check the file out
-again. `C-x v u' requires confirmation, unless it sees that you
-haven't made any changes since the last checked-in version.
-
- `C-x v u' is also the command to use if you lock a file and then
-don't actually change it.
-
- You can cancel a change after checking it in, with `C-x v c'
-(`vc-cancel-version'). This command discards all record of the most
-recent checked in version, so be careful about using it. It requires
-confirmation with `yes'. By default, `C-x v c' reverts your workfile
-and buffer to the previous version (the one that precedes the version
-that is deleted), but you can prevent the reversion by giving the
-command a prefix argument. Then the buffer does not change.
-
- This command with a prefix argument is useful when you have checked
-in a change and then discover a trivial error in it; you can cancel the
-erroneous check-in, fix the error, and repeat the check-in.
-
- Be careful when invoking `C-x v c', as it is easy to throw away a
-lot of work with it. To help you be careful, this command always
-requires confirmation with `yes'.
-
- You can register the visited file for version control using
-`C-x v i' (`vc-register'). If the variable `vc-default-back-end' is
-non-`nil', it specifies which version control system to use; otherwise,
-this uses RCS if it is installed on your system and SCCS if not. After
-`C-x v i', the file is unlocked and read-only. Type `C-x C-q' if you
-wish to edit it.
-
- By default, the initial version number is 1.1. If you want to use a
-different number, give `C-x v i' a prefix argument; then it reads the
-initial version number using the minibuffer.
-
- If `vc-initial-comment' is non-`nil', `C-x v i' reads an initial
-comment (much like a log entry) to describe the purpose of this source
-file.
-
- To specify the version number for a subsequent checkin, use the
-command `C-u C-x v v'. `C-x v v' (`vc-next-action') is the command
-that `C-x C-q' uses to do the "real work" when the visited file uses
-version control. When used for checkin, and given a prefix argument,
-it reads the version number with the minibuffer.
+would perform exactly the opposite replacements. To include a `\' in
+the text to replace with, you must give `\\'.
\1f
-File: xemacs.info, Node: Variables for Check-in/out, Next: Log Entries, Prev: Editing with VC, Up: Version Control
-
-Variables Affecting Check-in and Check-out
-------------------------------------------
-
- If `vc-suppress-confirm' is non-`nil', then `C-x C-q' and `C-x v i'
-can save the current buffer without asking, and `C-x v u' also operates
-without asking for confirmation. (This variable does not affect `C-x v
-c'; that is so drastic that it should always ask for confirmation.)
-
- VC mode does much of its work by running the shell commands for RCS
-and SCCS. If `vc-command-messages' is non-`nil', VC displays messages
-to indicate which shell commands it runs, and additional messages when
-the commands finish.
-
- Normally, VC assumes that it can deduce the locked/unlocked state of
-files by looking at the file permissions of the work file; this is
-fast. However, if the `RCS' or `SCCS' subdirectory is actually a
-symbolic link, then VC does not trust the file permissions to reflect
-this status.
-
- You can specify the criterion for whether to trust the file
-permissions by setting the variable `vc-mistrust-permissions'. Its
-value may be `t' (always mistrust the file permissions and check the
-master file), `nil' (always trust the file permissions), or a function
-of one argument which makes the decision. The argument is the directory
-name of the `RCS' or `SCCS' subdirectory. A non-`nil' value from the
-function says to mistrust the file permissions.
-
- If you find that the file permissions of work files are changed
-erroneously, set `vc-mistrust-permissions' to `t'. Then VC always
-checks the master file to determine the file's status.
-
- You can specify additional directories to search for version control
-programs by setting the variable `vc-path'. These directories are
-searched before the usual search path. The proper result usually
-happens automatically.
+File: xemacs.info, Node: Replacement and Case, Next: Query Replace, Prev: Regexp Replace, Up: Replace
-\1f
-File: xemacs.info, Node: Log Entries, Next: Change Logs and VC, Prev: Variables for Check-in/out, Up: Version Control
-
-Log Entries
------------
-
- When you're editing an initial comment or log entry for inclusion in
-a master file, finish your entry by typing `C-c C-c'.
-
-`C-c C-c'
- Finish the comment edit normally (`vc-finish-logentry'). This
- finishes check-in.
+Replace Commands and Case
+-------------------------
- To abort check-in, just don't type `C-c C-c' in that buffer. You
-can switch buffers and do other editing. As long as you don't try to
-check in another file, the entry you were editing remains in its
-buffer, and you can go back to that buffer at any time to complete the
-check-in.
+ If the arguments to a replace command are in lower case, the command
+preserves case when it makes a replacement. Thus, the following
+command:
- If you change several source files for the same reason, it is often
-convenient to specify the same log entry for many of the files. To do
-this, use the history of previous log entries. The commands `M-n',
-`M-p', `M-s' and `M-r' for doing this work just like the minibuffer
-history commands (except that these versions are used outside the
-minibuffer).
+ M-x replace-string <RET> foo <RET> bar <RET>
- Each time you check in a file, the log entry buffer is put into VC
-Log mode, which involves running two hooks: `text-mode-hook' and
-`vc-log-mode-hook'.
+replaces a lower-case `foo' with a lower case `bar', `FOO' with `BAR',
+and `Foo' with `Bar'. If upper-case letters are used in the second
+argument, they remain upper-case every time that argument 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 the variable `case-replace' is set to `nil',
+replacement is done without case conversion. If `case-fold-search' is
+set to `nil', case is significant in matching occurrences of `foo' to
+replace; also, case conversion of the replacement string is not done.
\1f
-File: xemacs.info, Node: Change Logs and VC, Next: Old Versions, Prev: Log Entries, Up: Version Control
+File: xemacs.info, Node: Query Replace, Prev: Replacement and Case, Up: Replace
-Change Logs and VC
-------------------
+Query Replace
+-------------
- If you use RCS for a program and also maintain a change log file for
-it (*note Change Log::), you can generate change log entries
-automatically from the version control log entries:
-
-`C-x v a'
- Visit the current directory's change log file and create new
- entries for versions checked in since the most recent entry in the
- change log file (`vc-update-change-log').
-
- This command works with RCS only; it does not work with SCCS.
-
- For example, suppose the first line of `ChangeLog' is dated 10 April
-1992, and that the only check-in since then was by Nathaniel Bowditch
-to `rcs2log' on 8 May 1992 with log text `Ignore log messages that
-start with `#'.'. Then `C-x v a' visits `ChangeLog' and inserts text
-like this:
-
- Fri May 8 21:45:00 1992 Nathaniel Bowditch (nat@apn.org)
-
- * rcs2log: Ignore log messages that start with `#'.
-
-You can then edit the new change log entry further as you wish.
-
- Normally, the log entry for file `foo' is displayed as `* foo: TEXT
-OF LOG ENTRY'. The `:' after `foo' is omitted if the text of the log
-entry starts with `(FUNCTIONNAME): '. For example, if the log entry
-for `vc.el' is `(vc-do-command): Check call-process status.', then the
-text in `ChangeLog' looks like this:
-
- Wed May 6 10:53:00 1992 Nathaniel Bowditch (nat@apn.org)
-
- * vc.el (vc-do-command): Check call-process status.
-
- When `C-x v a' adds several change log entries at once, it groups
-related log entries together if they all are checked in by the same
-author at nearly the same time. If the log entries for several such
-files all have the same text, it coalesces them into a single entry.
-For example, suppose the most recent checkins have the following log
-entries:
-
-For `vc.texinfo':
- Fix expansion typos.
-For `vc.el':
- Don't call expand-file-name.
-For `vc-hooks.el':
- Don't call expand-file-name.
-
- They appear like this in `ChangeLog':
-
- Wed Apr 1 08:57:59 1992 Nathaniel Bowditch (nat@apn.org)
-
- * vc.texinfo: Fix expansion typos.
-
- * vc.el, vc-hooks.el: Don't call expand-file-name.
-
- Normally, `C-x v a' separates log entries by a blank line, but you
-can mark several related log entries to be clumped together (without an
-intervening blank line) by starting the text of each related log entry
-with a label of the form `{CLUMPNAME} '. The label itself is not
-copied to `ChangeLog'. For example, suppose the log entries are:
-
-For `vc.texinfo':
- {expand} Fix expansion typos.
-For `vc.el':
- {expand} Don't call expand-file-name.
-For `vc-hooks.el':
- {expand} Don't call expand-file-name.
-
-Then the text in `ChangeLog' looks like this:
-
- Wed Apr 1 08:57:59 1992 Nathaniel Bowditch (nat@apn.org)
-
- * vc.texinfo: Fix expansion typos.
- * vc.el, vc-hooks.el: Don't call expand-file-name.
-
- A log entry whose text begins with `#' is not copied to `ChangeLog'.
-For example, if you merely fix some misspellings in comments, you can
-log the change with an entry beginning with `#' to avoid putting such
-trivia into `ChangeLog'.
+`M-% STRING <RET> NEWSTRING <RET>'
+`M-x query-replace <RET> STRING <RET> NEWSTRING <RET>'
+ Replace some occurrences of STRING with NEWSTRING.
-\1f
-File: xemacs.info, Node: Old Versions, Next: VC Status, Prev: Change Logs and VC, Up: Version Control
+`M-x query-replace-regexp <RET> REGEXP <RET> NEWSTRING <RET>'
+ Replace some matches for REGEXP with NEWSTRING.
-Examining And Comparing Old Versions
-------------------------------------
+ If you want to change only some of the occurrences of `foo' to
+`bar', not all of them, you can use `query-replace' instead of `M-%'.
+This command finds occurrences of `foo' one by one, displays each
+occurrence, and asks you whether to replace it. A numeric argument to
+`query-replace' tells it to consider only occurrences that are bounded
+by word-delimiter characters.
-`C-x v ~ VERSION <RET>'
- Examine version VERSION of the visited file, in a buffer of its
- own (`vc-version-other-window').
+ Aside from querying, `query-replace' works just like
+`replace-string', and `query-replace-regexp' works just like
+`replace-regexp'.
-`C-x v ='
- Compare the current buffer contents with the latest checked-in
- version of the file.
+ The things you can type when you are shown an occurrence of STRING
+or a match for REGEXP are:
-`C-u C-x v = FILE <RET> OLDVERS <RET> NEWVERS <RET>'
- Compare the specified two versions of FILE.
+`<SPC>'
+ to replace the occurrence with NEWSTRING. This preserves case,
+ just like `replace-string', provided `case-replace' is non-`nil',
+ as it normally is.
- You can examine any version of a file by first visiting it, and then
-using `C-x v ~ VERSION <RET>' (`vc-version-other-window'). This puts
-the text of version VERSION in a file named `FILENAME.~VERSION~', then
-visits it in a separate window.
+`<DEL>'
+ to skip to the next occurrence without replacing this one.
- To compare two versions of a file, use the command `C-x v ='
-(`vc-diff').
+`, (Comma)'
+ to replace this occurrence and display the result. You are then
+ prompted for another input character. However, since the
+ replacement has already been made, <DEL> and <SPC> are equivalent.
+ At this point, you can type `C-r' (see below) to alter the
+ replaced text. To undo the replacement, you can type `C-x u'.
+ This exits the `query-replace'. If you want to do further
+ replacement you must use `C-x ESC' to restart (*note Repetition::).
- Plain `C-x v =' compares the current buffer contents (saving them in
-the file if necessary) with the last checked-in version of the file.
-With a prefix argument, `C-x v =' reads a file name and two version
-numbers, then compares those versions of the specified file.
+`<ESC>'
+ to exit without doing any more replacements.
- If you supply a directory name instead of the name of a work file,
-this command compares the two specified versions of all registered files
-in that directory and its subdirectories. You can also specify a
-snapshot name (*note Snapshots::) instead of one or both version
-numbers.
+`. (Period)'
+ to replace this occurrence and then exit.
+
+`!'
+ to replace all remaining occurrences without asking again.
+
+`^'
+ to go back to the location of the previous occurrence (or what
+ used to be an occurrence), in case you changed it by mistake.
+ This works by popping the mark ring. Only one `^' in a row is
+ allowed, because only one previous replacement location is kept
+ during `query-replace'.
+
+`C-r'
+ to enter a recursive editing level, in case the occurrence needs
+ to be edited rather than just replaced with NEWSTRING. When you
+ are done, exit the recursive editing level with `C-M-c' and the
+ next occurrence will be displayed. *Note Recursive Edit::.
+
+`C-w'
+ to delete the occurrence, and then enter a recursive editing level
+ as in `C-r'. Use the recursive edit to insert text to replace the
+ deleted occurrence of STRING. When done, exit the recursive
+ editing level with `C-M-c' and the next occurrence will be
+ displayed.
+
+`C-l'
+ to redisplay the screen and then give another answer.
+
+`C-h'
+ to display a message summarizing these options, then give another
+ answer.
+
+ If you type any other character, Emacs exits the `query-replace', and
+executes the character as a command. To restart the `query-replace',
+use `C-x <ESC>', which repeats the `query-replace' because it used the
+minibuffer to read its arguments. *Note C-x ESC: Repetition.
- You can specify a checked-in version by its number; you can specify
-the most recent checked-in version with an empty version number.
+\1f
+File: xemacs.info, Node: Other Repeating Search, Prev: Replace, Up: Search
- This command works by running the `vcdiff' utility, getting the
-options from the variable `diff-switches'. It displays the output in a
-special buffer in another window. Unlike the `M-x diff' command, `C-x
-v =' does not try to find the changes in the old and new versions.
-This is because one or both versions normally do not exist as files.
-They exist only in the records of the master file. *Note Comparing
-Files::, for more information about `M-x diff'.
+Other Search-and-Loop Commands
+==============================
-\1f
-File: xemacs.info, Node: VC Status, Next: Renaming and VC, Prev: Old Versions, Up: Version Control
+ Here are some other commands that find matches for a regular
+expression. They all operate from point to the end of the buffer.
-VC Status Commands
-------------------
+`M-x occur'
+ Print each line that follows point and contains a match for the
+ specified regexp. A numeric argument specifies the number of
+ context lines to print before and after each matching line; the
+ default is none.
- To view the detailed version control status and history of a file,
-type `C-x v l' (`vc-print-log'). It displays the history of changes to
-the current file, including the text of the log entries. The output
-appears in a separate window.
-
- When you are working on a large program, it's often useful to find
-all the files that are currently locked, or all the files maintained in
-version control at all. You can use `C-x v d' (`vc-directory') to show
-all the locked files in or beneath the current directory. This
-includes all files that are locked by any user. `C-u C-x v d' lists
-all files in or beneath the current directory that are maintained with
-version control.
-
- The list of files is displayed as a buffer that uses an augmented
-Dired mode. The names of the users locking various files are shown (in
-parentheses) in place of the owner and group. All the normal Dired
-commands work in this buffer. Most interactive VC commands work also,
-and apply to the file name on the current line.
-
- The `C-x v v' command (`vc-next-action'), when used in the augmented
-Dired buffer, operates on all the marked files (or the file on the
-current line). If it operates on more than one file, it handles each
-file according to its current state; thus, it may check out one file
-and check in another (because it is already checked out). If it has to
-check in any files, it reads a single log entry, then uses that text
-for all the files being checked in. This can be convenient for
-registering or checking in several files at once, as part of the same
-change.
+ The buffer `*Occur*' containing the output serves as a menu for
+ finding occurrences in their original context. Find an occurrence
+ as listed in `*Occur*', position point there, and type `C-c C-c';
+ this switches to the buffer that was searched and moves point to
+ the original of the same occurrence.
-\1f
-File: xemacs.info, Node: Renaming and VC, Next: Snapshots, Prev: VC Status, Up: Version Control
+`M-x list-matching-lines'
+ Synonym for `M-x occur'.
-Renaming VC Work Files and Master Files
----------------------------------------
+`M-x count-matches'
+ Print the number of matches following point for the specified
+ regexp.
- When you rename a registered file, you must also rename its master
-file correspondingly to get proper results. Use `vc-rename-file' to
-rename the source file as you specify, and rename its master file
-accordingly. It also updates any snapshots (*note Snapshots::) that
-mention the file, so that they use the new name; despite this, the
-snapshot thus modified may not completely work (*note Snapshot
-Caveats::).
+`M-x delete-non-matching-lines'
+ Delete each line that follows point and does not contain a match
+ for the specified regexp.
- You cannot use `vc-rename-file' on a file that is locked by someone
-else.
+`M-x delete-matching-lines'
+ Delete each line that follows point and contains a match for the
+ specified regexp.
\1f
-File: xemacs.info, Node: Snapshots, Next: Version Headers, Prev: Renaming and VC, Up: Version Control
+File: xemacs.info, Node: Fixit, Next: Files, Prev: Search, Up: Top
-Snapshots
----------
+Commands for Fixing Typos
+*************************
- A "snapshot" is a named set of file versions (one for each
-registered file) that you can treat as a unit. One important kind of
-snapshot is a "release", a (theoretically) stable version of the system
-that is ready for distribution to users.
+ This chapter describes commands that are especially useful when you
+catch a mistake in your text just after you have made it, or when you
+change your mind while composing text on line.
* Menu:
-* Making Snapshots:: The snapshot facilities.
-* Snapshot Caveats:: Things to be careful of when using snapshots.
+* Kill Errors:: Commands to kill a batch of recently entered text.
+* Transpose:: Exchanging two characters, words, lines, lists...
+* Fixing Case:: Correcting case of last word entered.
+* Spelling:: Apply spelling checker to a word, or a whole file.
\1f
-File: xemacs.info, Node: Making Snapshots, Next: Snapshot Caveats, Prev: Snapshots, Up: Snapshots
+File: xemacs.info, Node: Kill Errors, Next: Transpose, Prev: Fixit, Up: Fixit
-Making and Using Snapshots
-..........................
+Killing Your Mistakes
+=====================
- There are two basic commands for snapshots; one makes a snapshot
-with a given name, the other retrieves a named snapshot.
+`<DEL>'
+ Delete last character (`delete-backward-char').
-`C-x v s NAME <RET>'
- Define the last saved versions of every registered file in or
- under the current directory as a snapshot named NAME
- (`vc-create-snapshot').
+`M-<DEL>'
+ Kill last word (`backward-kill-word').
-`C-x v r NAME <RET>'
- Check out all registered files at or below the current directory
- level using whatever versions correspond to the snapshot NAME
- (`vc-retrieve-snapshot').
+`C-x <DEL>'
+ Kill to beginning of sentence (`backward-kill-sentence').
- This command reports an error if any files are locked at or below
- the current directory, without changing anything; this is to avoid
- overwriting work in progress.
+ The <DEL> character (`delete-backward-char') is the most important
+correction command. When used among graphic (self-inserting)
+characters, it can be thought of as canceling the last character typed.
- A snapshot uses a very small amount of resources--just enough to
-record the list of file names and which version belongs to the
-snapshot. Thus, you need not hesitate to create snapshots whenever
-they are useful.
+ When your mistake is longer than a couple of characters, it might be
+more convenient to use `M-<DEL>' or `C-x <DEL>'. `M-<DEL>' kills back
+to the start of the last word, and `C-x <DEL>' kills back to the start
+of the last sentence. `C-x <DEL>' is particularly useful when you are
+thinking of what to write as you type it, in case you change your mind
+about phrasing. `M-<DEL>' and `C-x <DEL>' save the killed text for
+`C-y' and `M-y' to retrieve. *Note Yanking::.
- You can give a snapshot name as an argument to `C-x v =' or `C-x v
-~' (*note Old Versions::). Thus, you can use it to compare a snapshot
-against the current files, or two snapshots against each other, or a
-snapshot against a named version.
+ `M-<DEL>' is often useful even when you have typed only a few
+characters wrong, if you know you are confused in your typing and aren't
+sure exactly what you typed. At such a time, you cannot correct with
+<DEL> except by looking at the screen to see what you did. It requires
+less thought to kill the whole word and start over.
\1f
-File: xemacs.info, Node: Snapshot Caveats, Prev: Making Snapshots, Up: Snapshots
-
-Snapshot Caveats
-................
-
- VC's snapshot facilities are modeled on RCS's named-configuration
-support. They use RCS's native facilities for this, so under VC
-snapshots made using RCS are visible even when you bypass VC.
-
- For SCCS, VC implements snapshots itself. The files it uses contain
-name/file/version-number triples. These snapshots are visible only
-through VC.
-
- A snapshot is a set of checked-in versions. So make sure that all
-the files are checked in and not locked when you make a snapshot.
-
- File renaming and deletion can create some difficulties with
-snapshots. This is not a VC-specific problem, but a general design
-issue in version control systems that no one has solved very well yet.
-
- If you rename a registered file, you need to rename its master along
-with it (the command `vc-rename-file' does this automatically). If you
-are using SCCS, you must also update the records of the snapshot, to
-mention the file by its new name (`vc-rename-file' does this, too). An
-old snapshot that refers to a master file that no longer exists under
-the recorded name is invalid; VC can no longer retrieve it. It would
-be beyond the scope of this manual to explain enough about RCS and SCCS
-to explain how to update the snapshots by hand.
-
- Using `vc-rename-file' makes the snapshot remain valid for
-retrieval, but it does not solve all problems. For example, some of the
-files in the program probably refer to others by name. At the very
-least, the makefile probably mentions the file that you renamed. If you
-retrieve an old snapshot, the renamed file is retrieved under its new
-name, which is not the name that the makefile expects. So the program
-won't really work as retrieved.
+File: xemacs.info, Node: Transpose, Next: Fixing Case, Prev: Kill Errors, Up: Fixit
+
+Transposing Text
+================
+
+`C-t'
+ Transpose two characters (`transpose-chars').
+
+`M-t'
+ Transpose two words (`transpose-words').
+
+`C-M-t'
+ Transpose two balanced expressions (`transpose-sexps').
+
+`C-x C-t'
+ Transpose two lines (`transpose-lines').
+
+ The common error of transposing two adjacent characters can be fixed
+with the `C-t' command (`transpose-chars'). Normally, `C-t' transposes
+the two characters on either side of point. When given at the end of a
+line, `C-t' transposes the last two characters on the line, rather than
+transposing the last character of the line with the newline, which
+would be useless. If you catch a transposition error right away, you
+can fix it with just `C-t'. If you catch the error later, move the
+cursor back to between the two transposed characters. If you
+transposed a space with the last character of the word before it, the
+word motion commands are a good way of getting there. Otherwise, a
+reverse search (`C-r') is often the best way. *Note Search::.
+
+ `Meta-t' (`transpose-words') transposes the word before point with
+the word after point. It moves point forward over a word, dragging the
+word preceding or containing point forward as well. The punctuation
+characters between the words do not move. For example, `FOO, BAR'
+transposes into `BAR, FOO' rather than `BAR FOO,'.
+
+ `C-M-t' (`transpose-sexps') is a similar command for transposing two
+expressions (*note Lists::), and `C-x C-t' (`transpose-lines')
+exchanges lines. It works like `M-t' but in determines the division of
+the text into syntactic units differently.
+
+ A numeric argument to a transpose command serves as a repeat count:
+it tells the transpose command to move the character (word, sexp, line)
+before or containing point across several other characters (words,
+sexps, lines). For example, `C-u 3 C-t' moves the character before
+point forward across three other characters. This is equivalent to
+repeating `C-t' three times. `C-u - 4 M-t' moves the word before point
+backward across four words. `C-u - C-M-t' would cancel the effect of
+plain `C-M-t'.
+
+ A numeric argument of zero transposes the character (word, sexp,
+line) ending after point with the one ending after the mark (otherwise a
+command with a repeat count of zero would do nothing).
\1f
-File: xemacs.info, Node: Version Headers, Prev: Snapshots, Up: Version Control
-
-Inserting Version Control Headers
----------------------------------
-
- Sometimes it is convenient to put version identification strings
-directly into working files. Certain special strings called "version
-headers" are replaced in each successive version by the number of that
-version.
-
- You can use the `C-x v h' command (`vc-insert-headers') to insert a
-suitable header string.
-
-`C-x v h'
- Insert headers in a file for use with your version-control system.
-
- The default header string is `\$Id\$' for RCS and `\%W\%' for SCCS.
-(The actual strings inserted do not have the backslashes in them. They
-were placed in the Info source file so that the strings don't get
-interpreted as version-control headers when the Info source files are
-maintained under version control.) You can specify other headers to
-insert by setting the variable `vc-header-alist'. Its value is a list
-of elements of the form `(PROGRAM . STRING)' where PROGRAM is `RCS' or
-`SCCS' and STRING is the string to use.
-
- Instead of a single string, you can specify a list of strings; then
-each string in the list is inserted as a separate header on a line of
-its own.
-
- It is often necessary to use "superfluous" backslashes when writing
-the strings that you put in this variable. This is to prevent the
-string in the constant from being interpreted as a header itself if the
-Emacs Lisp file containing it is maintained with version control.
-
- Each header is inserted surrounded by tabs, inside comment
-delimiters, on a new line at the start of the buffer. Normally the
-ordinary comment start and comment end strings of the current mode are
-used, but for certain modes, there are special comment delimiters for
-this purpose; the variable `vc-comment-alist' specifies them. Each
-element of this list has the form `(MODE STARTER ENDER)'.
-
- The variable `vc-static-header-alist' specifies further strings to
-add based on the name of the buffer. Its value should be a list of
-elements of the form `(REGEXP . FORMAT)'. Whenever REGEXP matches the
-buffer name, FORMAT is inserted as part of the header. A header line
-is inserted for each element that matches the buffer name, and for each
-string specified by `vc-header-alist'. The header line is made by
-processing the string from `vc-header-alist' with the format taken from
-the element. The default value for `vc-static-header-alist' is:
-
- (("\\.c$" .
- "\n#ifndef lint\nstatic char vcid[] = \"\%s\";\n\
- #endif /* lint */\n"))
-
-which specifies insertion of a string of this form:
-
-
- #ifndef lint
- static char vcid[] = "STRING";
- #endif /* lint */
+File: xemacs.info, Node: Fixing Case, Next: Spelling, Prev: Transpose, Up: Fixit
-\1f
-File: xemacs.info, Node: ListDir, Next: Comparing Files, Prev: Version Control, Up: Files
+Case Conversion
+===============
-Listing a File Directory
-========================
+`M-- M-l'
+ Convert last word to lower case. Note that `Meta--' is
+ "Meta-minus."
- Files are organized by Unix into "directories". A "directory
-listing" is a list of all the files in a directory. Emacs provides
-directory listings in brief format (file names only) and verbose format
-(sizes, dates, and authors included).
+`M-- M-u'
+ Convert last word to all upper case.
-`C-x C-d DIR-OR-PATTERN'
- Print a brief directory listing (`list-directory').
+`M-- M-c'
+ Convert last word to lower case with capital initial.
-`C-u C-x C-d DIR-OR-PATTERN'
- Print a verbose directory listing.
+ A common error is to type words in the wrong case. Because of this,
+the word case-conversion commands `M-l', `M-u', and `M-c' do not move
+the cursor when used with a negative argument. As soon as you see you
+have mistyped the last word, you can simply case-convert it and
+continue typing. *Note Case::.
- To print a directory listing, use `C-x C-d' (`list-directory').
-This command prompts in the minibuffer for a file name which is either
-a directory to be listed or pattern containing wildcards for the files
-to be listed. For example,
+\1f
+File: xemacs.info, Node: Spelling, Prev: Fixing Case, Up: Fixit
- C-x C-d /u2/emacs/etc <RET>
+Checking and Correcting Spelling
+================================
-lists all the files in directory `/u2/emacs/etc'. An example of
-specifying a file name pattern is:
+`M-$'
+ Check and correct spelling of word (`spell-word').
- C-x C-d /u2/emacs/src/*.c <RET>
+`M-x spell-buffer'
+ Check and correct spelling of each word in the buffer.
- Normally, `C-x C-d' prints a brief directory listing containing just
-file names. A numeric argument (regardless of value) tells it to print
-a verbose listing (like `ls -l').
+`M-x spell-region'
+ Check and correct spelling of each word in the region.
- Emacs obtains the text of a directory listing by running `ls' in an
-inferior process. Two Emacs variables control the switches passed to
-`ls': `list-directory-brief-switches' is a string giving the switches
-to use in brief listings (`"-CF"' by default).
-`list-directory-verbose-switches' is a string giving the switches to
-use in a verbose listing (`"-l"' by default).
+`M-x spell-string'
+ Check spelling of specified word.
- The variable `directory-abbrev-alist' is an alist of abbreviations
-for file directories. The list consists of elements of the form `(FROM
-. TO)', each meaning to replace `FROM' with `TO' when it appears in a
-directory name. This replacement is done when setting up the default
-directory of a newly visited file. Every `FROM' string should start
-with ``^''.
+ To check the spelling of the word before point, and optionally
+correct it, use the command `M-$' (`spell-word'). This command runs an
+inferior process containing the `spell' program to see whether the word
+is correct English. If it is not, it asks you to edit the word (in the
+minibuffer) into a corrected spelling, and then performs a
+`query-replace' to substitute the corrected spelling for the old one
+throughout the buffer.
- Use this feature when you have directories which you normally refer
-to via absolute symbolic links. Make `TO' the name of the link, and
-`FROM' the name it is linked to.
+ If you exit the minibuffer without altering the original spelling, it
+means you do not want to do anything to that word. In that case, the
+`query-replace' is not done.
-\1f
-File: xemacs.info, Node: Comparing Files, Next: Dired, Prev: ListDir, Up: Files
+ `M-x spell-buffer' checks each word in the buffer the same way that
+`spell-word' does, doing a `query-replace' for every incorrect word if
+appropriate.
-Comparing Files
-===============
+ `M-x spell-region' is similar to `spell-buffer' but operates only on
+the region, not the entire buffer.
- The command `M-x diff' compares two files, displaying the
-differences in an Emacs buffer named `*Diff*'. It works by running the
-`diff' program, using options taken from the variable `diff-switches',
-whose value should be a string.
-
- The buffer `*Diff*' has Compilation mode as its major mode, so you
-can use `C-x `' to visit successive changed locations in the two source
-files. You can also move to a particular hunk of changes and type `C-c
-C-c' to find the corresponding source location. You can also use the
-other special commands of Compilation mode: <SPC> and <DEL> for
-scrolling, and `M-p' and `M-n' for cursor motion. *Note Compilation::.
-
- The command `M-x diff-backup' compares a specified file with its most
-recent backup. If you specify the name of a backup file, `diff-backup'
-compares it with the source file that it is a backup of.
-
- The command `M-x compare-windows' compares the text in the current
-window with that in the next window. Comparison starts at point in each
-window. Point moves forward in each window, a character at a time in
-each window, until the next characters in the two windows are
-different. Then the command is finished. For more information about
-windows in Emacs, *Note Windows::.
-
- With a numeric argument, `compare-windows' ignores changes in
-whitespace. If the variable `compare-ignore-case' is non-`nil', it
-ignores differences in case as well.
+ `M-x spell-string' reads a string as an argument and checks whether
+that is a correctly spelled English word. It prints a message giving
+the answer in the echo area.
\1f
-File: xemacs.info, Node: Dired, Next: Misc File Ops, Prev: Comparing Files, Up: Files
+File: xemacs.info, Node: Files, Next: Buffers, Prev: Fixit, Up: Top
+
+File Handling
+*************
-Dired, the Directory Editor
-===========================
+ The basic unit of stored data in Unix is the "file". To edit a file,
+you must tell Emacs to examine the file and prepare a buffer containing
+a copy of the file's text. This is called "visiting" the file. Editing
+commands apply directly to text in the buffer; that is, to the copy
+inside Emacs. Your changes appear in the file itself only when you
+"save" the buffer back into the file.
- Dired makes it easy to delete or visit many of the files in a single
-directory at once. It creates an Emacs buffer containing a listing of
-the directory. You can use the normal Emacs commands to move around in
-this buffer and special Dired commands to operate on the files.
+ In addition to visiting and saving files, Emacs can delete, copy,
+rename, and append to files, and operate on file directories.
* Menu:
-* Enter: Dired Enter. How to invoke Dired.
-* Edit: Dired Edit. Editing the Dired buffer.
-* Deletion: Dired Deletion. Deleting files with Dired.
-* Immed: Dired Immed. Other file operations through Dired.
+* File Names:: How to type and edit file name arguments.
+* Visiting:: Visiting a file prepares Emacs to edit the file.
+* Saving:: Saving makes your changes permanent.
+* Reverting:: Reverting cancels all the changes not saved.
+* Auto Save:: Auto Save periodically protects against loss of data.
+* Version Control:: Version control systems (RCS and SCCS).
+* ListDir:: Listing the contents of a file directory.
+* Comparing Files:: Finding where two files differ.
+* Dired:: ``Editing'' a directory to delete, rename, etc.
+ the files in it.
+* Misc File Ops:: Other things you can do on files.
\1f
-File: xemacs.info, Node: Dired Enter, Next: Dired Edit, Prev: Dired, Up: Dired
+File: xemacs.info, Node: File Names, Next: Visiting, Prev: Files, Up: Files
+
+File Names
+==========
+
+ Most Emacs commands that operate on a file require you to specify the
+file name. (Saving and reverting are exceptions; the buffer knows which
+file name to use for them.) File names are specified in the minibuffer
+(*note Minibuffer::). "Completion" is available, to make it easier to
+specify long file names. *Note Completion::.
+
+ There is always a "default file name" which is used if you enter an
+empty argument by typing just <RET>. Normally the default file name is
+the name of the file visited in the current buffer; this makes it easy
+to operate on that file with any of the Emacs file commands.
+
+ Each buffer has a default directory, normally the same as the
+directory of the file visited in that buffer. When Emacs reads a file
+name, the default directory is used if you do not specify a directory.
+If you specify a directory in a relative fashion, with a name that does
+not start with a slash, it is interpreted with respect to the default
+directory. The default directory of the current buffer is kept in the
+variable `default-directory', which has a separate value in every
+buffer. The value of the variable should end with a slash.
+
+ For example, if the default file name is `/u/rms/gnu/gnu.tasks' then
+the default directory is `/u/rms/gnu/'. If you type just `foo', which
+does not specify a directory, it is short for `/u/rms/gnu/foo'.
+`../.login' would stand for `/u/rms/.login'. `new/foo' would stand for
+the filename `/u/rms/gnu/new/foo'.
+
+ The variable `default-directory-alist' takes an alist of major modes
+and their opinions on `default-directory' as a Lisp expression to
+evaluate. A resulting value of `nil' is ignored in favor of
+`default-directory'.
+
+ You can create a new directory with the function `make-directory',
+which takes as an argument a file name string. The current directory is
+displayed in the minibuffer when the function is called; you can delete
+the old directory name and supply a new directory name. For example, if
+the current directory is `/u/rms/gnu', you can delete `gnu' and type
+`oryx' and <RET> to create `/u/rms/oryx'. Removing a directory is
+similar to creating one. To remove a directory, use
+`remove-directory'; it takes one argument, a file name string.
+
+ The command `M-x pwd' prints the current buffer's default directory,
+and the command `M-x cd' sets it (to a value read using the
+minibuffer). A buffer's default directory changes only when the `cd'
+command is used. A file-visiting buffer's default directory is
+initialized to the directory of the file that is visited there. If a
+buffer is created with `C-x b', its default directory is copied from
+that of the buffer that was current at the time.
+
+ The default directory name actually appears in the minibuffer when
+the minibuffer becomes active to read a file name. This serves two
+purposes: it shows you what the default is, so that you can type a
+relative file name and know with certainty what it will mean, and it
+allows you to edit the default to specify a different directory. To
+inhibit the insertion of the default directory, set the variable
+`insert-default-directory' to `nil'.
+
+ Note that it is legitimate to type an absolute file name after you
+enter the minibuffer, ignoring the presence of the default directory
+name. The final minibuffer contents may look invalid, but that is not
+so. *Note Minibuffer File::.
+
+ `$' in a file name is used to substitute environment variables. For
+example, if you have used the shell command `setenv FOO rms/hacks' to
+set up an environment variable named `FOO', then you can use
+`/u/$FOO/test.c' or `/u/${FOO}/test.c' as an abbreviation for
+`/u/rms/hacks/test.c'. The environment variable name consists of all
+the alphanumeric characters after the `$'; alternatively, it may be
+enclosed in braces after the `$'. Note that the `setenv' command
+affects Emacs only if done before Emacs is started.
+
+ To access a file with `$' in its name, type `$$'. This pair is
+converted to a single `$' at the same time variable substitution is
+performed for single `$'. The Lisp function that performs the
+substitution is called `substitute-in-file-name'. The substitution is
+performed only on filenames read as such using the minibuffer.
-Entering Dired
---------------
+\1f
+File: xemacs.info, Node: Visiting, Next: Saving, Prev: File Names, Up: Files
+
+Visiting Files
+==============
+
+`C-x C-f'
+ Visit a file (`find-file').
+
+`C-x C-v'
+ Visit a different file instead of the one visited last
+ (`find-alternate-file').
+
+`C-x 4 C-f'
+ Visit a file, in another window (`find-file-other-window'). Don't
+ change this window.
+
+`C-x 5 C-f'
+ Visit a file, in another frame (`find-file-other-frame'). Don't
+ change this window or frame.
+
+ "Visiting" a file means copying its contents into an Emacs buffer so
+you can edit it. Emacs creates a new buffer for each file you visit.
+We say that the buffer is visiting the file that it was created to
+hold. Emacs constructs the buffer name from the file name by throwing
+away the directory and keeping just the file name. For example, a file
+named `/usr/rms/emacs.tex' is displayed in a buffer named `emacs.tex'.
+If a buffer with that name exists, a unique name is constructed by
+appending `<2>', `<3>',and so on, using the lowest number that makes a
+name that is not already in use.
+
+ Each window's mode line shows the name of the buffer that is being
+displayed in that window, so you can always tell what buffer you are
+editing.
+
+ The changes you make with Emacs are made in the Emacs buffer. They
+do not take effect in the file that you visit, or any other permanent
+place, until you "save" the buffer. Saving the buffer means that Emacs
+writes the current contents of the buffer into its visited file. *Note
+Saving::.
+
+ If a buffer contains changes that have not been saved, the buffer is
+said to be "modified". This is important because it implies that some
+changes will be lost if the buffer is not saved. The mode line displays
+two stars near the left margin if the buffer is modified.
+
+ To visit a file, use the command `C-x C-f' (`find-file'). Follow
+the command with the name of the file you wish to visit, terminated by a
+<RET>. If you are using XEmacs under X, you can also use the Open...
+command from the File menu bar item.
+
+ The file name is read using the minibuffer (*note Minibuffer::), with
+defaulting and completion in the standard manner (*note File Names::).
+While in the minibuffer, you can abort `C-x C-f' by typing `C-g'.
+
+ `C-x C-f' has completed successfully when text appears on the screen
+and a new buffer name appears in the mode line. If the specified file
+does not exist and could not be created or cannot be read, an error
+results. The error message is printed in the echo area, and includes
+the name of the file that Emacs was trying to visit.
+
+ If you visit a file that is already in Emacs, `C-x C-f' does not make
+another copy. It selects the existing buffer containing that file.
+However, before doing so, it checks that the file itself has not changed
+since you visited or saved it last. If the file has changed, Emacs
+prints a warning message. *Note Simultaneous Editing: Interlocking.
+
+ You can switch to a specific file called out in the current buffer by
+calling the function `find-this-file'. By providing a prefix argument,
+this function calls `filename-at-point' and switches to a buffer
+visiting the file FILENAME. It creates one if none already exists. You
+can use this function to edit the file mentioned in the buffer you are
+working in or to test if the file exists. You can do that by using the
+minibuffer completion after snatching the all or part of the filename.
+
+ If the variable `find-file-use-truenames''s value is non-`nil', a
+buffer's visited filename will always be traced back to the real file.
+The filename will never be a symbolic link, and there will never be a
+symbolic link anywhere in its directory path. In other words, the
+`buffer-file-name' and `buffer-file-truename' will be equal.
+
+ If the variable `find-file-compare-truenames' value is non-`nil',
+the `find-file' command will check the `buffer-file-truename' of all
+visited files when deciding whether a given file is already in a
+buffer, instead of just `buffer-file-name'. If you attempt to visit
+another file which is a symbolic link to a file that is already in a
+buffer, the existing buffer will be found instead of a newly created
+one. This works if any component of the pathname (including a
+non-terminal component) is a symbolic link as well, but doesn't work
+with hard links (nothing does).
+
+ If you want to create a file, just visit it. Emacs prints `(New
+File)' in the echo area, but in other respects behaves as if you had
+visited an existing empty file. If you make any changes and save them,
+the file is created.
+
+ If you visit a nonexistent file unintentionally (because you typed
+the wrong file name), use the `C-x C-v' (`find-alternate-file') command
+to visit the file you wanted. `C-x C-v' is similar to `C-x C-f', but
+it kills the current buffer (after first offering to save it if it is
+modified). `C-x C-v' is allowed even if the current buffer is not
+visiting a file.
+
+ If the file you specify is actually a directory, Dired is called on
+that directory (*note Dired::). To inhibit this, set the variable
+`find-file-run-dired' to `nil'; then it is an error to try to visit a
+directory.
+
+ `C-x 4 f' (`find-file-other-window') is like `C-x C-f' except that
+the buffer containing the specified file is selected in another window.
+The window that was selected before `C-x 4 f' continues to show the
+same buffer it was already showing. If you use this command when only
+one window is being displayed, that window is split in two, with one
+window showing the same buffer as before, and the other one showing the
+newly requested file. *Note Windows::.
+
+ `C-x 5 C-f' (`find-file-other-frame') is like `C-x C-f' except that
+it creates a new frame in which the file is displayed.
+
+ Use the function `find-this-file-other-window' to edit a file
+mentioned in the buffer you are editing or to test if that file exists.
+To do this, use the minibuffer completion after snatching the part or
+all of the filename. By providing a prefix argument, the function calls
+`filename-at-point' and switches you to a buffer visiting the file
+FILENAME in another window. The function creates a buffer if none
+already exists. This function is similar to `find-file-other-window'.
+
+ There are two hook variables that allow extensions to modify the
+operation of visiting files. Visiting a file that does not exist runs
+the functions in the list `find-file-not-found-hooks'; the value of this
+variable is expected to be a list of functions which are called one by
+one until one of them returns non-`nil'. Any visiting of a file,
+whether extant or not, expects `find-file-hooks' to contain list of
+functions and calls them all, one by one. In both cases the functions
+receive no arguments. Visiting a nonexistent file runs the
+`find-file-not-found-hooks' first.
- To invoke dired, type `C-x d' or `M-x dired'. The command reads a
-directory name or wildcard file name pattern as a minibuffer argument
-just like the `list-directory' command, `C-x C-d'. Where `dired'
-differs from `list-directory' is in naming the buffer after the
-directory name or the wildcard pattern used for the listing, and putting
-the buffer into Dired mode so that the special commands of Dired are
-available in it. The variable `dired-listing-switches' is a string
-used as an argument to `ls' in making the directory; this string must
-contain `-l'.
+\1f
+File: xemacs.info, Node: Saving, Next: Reverting, Prev: Visiting, Up: Files
+
+Saving Files
+============
+
+ "Saving" a buffer in Emacs means writing its contents back into the
+file that was visited in the buffer.
+
+`C-x C-s'
+ Save the current buffer in its visited file (`save-buffer').
+
+`C-x s'
+ Save any or all buffers in their visited files
+ (`save-some-buffers').
+
+`M-~'
+ Forget that the current buffer has been changed (`not-modified').
+
+`C-x C-w'
+ Save the current buffer in a specified file, and record that file
+ as the one visited in the buffer (`write-file').
+
+`M-x set-visited-file-name'
+ Change file the name under which the current buffer will be saved.
+
+ To save a file and make your changes permanent, type `C-x C-s'
+(`save-buffer'). After saving is finished, `C-x C-s' prints a message
+such as:
+
+ Wrote /u/rms/gnu/gnu.tasks
+
+If the selected buffer is not modified (no changes have been made in it
+since the buffer was created or last saved), Emacs does not save it
+because it would have no effect. Instead, `C-x C-s' prints a message
+in the echo area saying:
+
+ (No changes need to be saved)
+
+ The command `C-x s' (`save-some-buffers') can save any or all
+modified buffers. First it asks, for each modified buffer, whether to
+save it. The questions should be answered with `y' or `n'. `C-x C-c',
+the key that kills Emacs, invokes `save-some-buffers' and therefore
+asks the same questions.
+
+ If you have changed a buffer and do not want the changes to be saved,
+you should take some action to prevent it. Otherwise, you are liable to
+save it by mistake each time you use `save-some-buffers' or a related
+command. One thing you can do is type `M-~' (`not-modified'), which
+removes the indication that the buffer is modified. If you do this,
+none of the save commands will believe that the buffer needs to be
+saved. (`~' is often used as a mathematical symbol for `not'; thus
+`Meta-~' is `not', metafied.) You could also use
+`set-visited-file-name' (see below) to mark the buffer as visiting a
+different file name, not in use for anything important.
+
+ You can also undo all the changes made since the file was visited or
+saved, by reading the text from the file again. This is called
+"reverting". *Note Reverting::. Alternatively, you can undo all the
+changes by repeating the undo command `C-x u'; but this only works if
+you have not made more changes than the undo mechanism can remember.
+
+ `M-x set-visited-file-name' alters the name of the file that the
+current buffer is visiting. It prompts you for the new file name in the
+minibuffer. You can also use `set-visited-file-name' on a buffer that
+is not visiting a file. The buffer's name is changed to correspond to
+the file it is now visiting unless the new name is already used by a
+different buffer; in that case, the buffer name is not changed.
+`set-visited-file-name' does not save the buffer in the newly visited
+file; it just alters the records inside Emacs so that it will save the
+buffer in that file. It also marks the buffer as "modified" so that
+`C-x C-s' will save.
+
+ If you wish to mark a buffer as visiting a different file and save it
+right away, use `C-x C-w' (`write-file'). It is precisely equivalent
+to `set-visited-file-name' followed by `C-x C-s'. `C-x C-s' used on a
+buffer that is not visiting a file has the same effect as `C-x C-w';
+that is, it reads a file name, marks the buffer as visiting that file,
+and saves it there. The default file name in a buffer that is not
+visiting a file is made by combining the buffer name with the buffer's
+default directory.
+
+ If Emacs is about to save a file and sees that the date of the latest
+version on disk does not match what Emacs last read or wrote, Emacs
+notifies you of this fact, because it probably indicates a problem
+caused by simultaneous editing and requires your immediate attention.
+*Note Simultaneous Editing: Interlocking.
+
+ If the variable `require-final-newline' is non-`nil', Emacs puts a
+newline at the end of any file that doesn't already end in one, every
+time a file is saved or written.
+
+ Use the hook variable `write-file-hooks' to implement other ways to
+write files, and specify things to be done before files are written.
+The value of this variable should be a list of Lisp functions. When a
+file is to be written, the functions in the list are called, one by
+one, with no arguments. If one of them returns a non-`nil' value, Emacs
+takes this to mean that the file has been written in some suitable
+fashion; the rest of the functions are not called, and normal writing is
+not done. Use the hook variable `after-save-hook' to list all the
+functions to be called after writing out a buffer to a file.
- To display the Dired buffer in another window rather than in the
-selected window, use `C-x 4 d' (`dired-other-window)' instead of `C-x
-d'.
+* Menu:
+
+* Backup:: How Emacs saves the old version of your file.
+* Interlocking:: How Emacs protects against simultaneous editing
+ of one file by two users.
\1f
-File: xemacs.info, Node: Dired Edit, Next: Dired Deletion, Prev: Dired Enter, Up: Dired
-
-Editing in Dired
-----------------
-
- Once the Dired buffer exists, you can switch freely between it and
-other Emacs buffers. Whenever the Dired buffer is selected, certain
-special commands are provided that operate on files that are listed.
-The Dired buffer is "read-only", and inserting text in it is not
-useful, so ordinary printing characters such as `d' and `x' are used
-for Dired commands. Most Dired commands operate on the file described
-by the line that point is on. Some commands perform operations
-immediately; others "flag" a file to be operated on later.
-
- Most Dired commands that operate on the current line's file also
-treat a numeric argument as a repeat count, meaning to act on the files
-of the next few lines. A negative argument means to operate on the
-files of the preceding lines, and leave point on the first of those
-lines.
-
- All the usual Emacs cursor motion commands are available in Dired
-buffers. Some special purpose commands are also provided. The keys
-`C-n' and `C-p' are redefined so that they try to position the cursor
-at the beginning of the filename on the line, rather than at the
-beginning of the line.
-
- For extra convenience, <SPC> and `n' in Dired are equivalent to
-`C-n'. `p' is equivalent to `C-p'. Moving by lines is done so often
-in Dired that it deserves to be easy to type. <DEL> (move up and
-unflag) is often useful simply for moving up.
-
- The `g' command in Dired runs `revert-buffer' to reinitialize the
-buffer from the actual disk directory and show any changes made in the
-directory by programs other than Dired. All deletion flags in the Dired
-buffer are lost when this is done.
+File: xemacs.info, Node: Backup, Next: Interlocking, Prev: Saving, Up: Saving
+
+Backup Files
+------------
+
+ Because Unix does not provide version numbers in file names,
+rewriting a file in Unix automatically destroys all record of what the
+file used to contain. Thus, saving a file from Emacs throws away the
+old contents of the file--or it would, except that Emacs carefully
+copies the old contents to another file, called the "backup" file,
+before actually saving. (Make sure that the variable
+`make-backup-files' is non-`nil'. Backup files are not written if this
+variable is `nil').
+
+ At your option, Emacs can keep either a single backup file or a
+series of numbered backup files for each file you edit.
+
+ Emacs makes a backup for a file only the first time a file is saved
+from one buffer. No matter how many times you save a file, its backup
+file continues to contain the contents from before the file was visited.
+Normally this means that the backup file contains the contents from
+before the current editing session; however, if you kill the buffer and
+then visit the file again, a new backup file is made by the next save.
+
+* Menu:
+
+* Names: Backup Names. How backup files are named;
+ Choosing single or numbered backup files.
+* Deletion: Backup Deletion. Emacs deletes excess numbered backups.
+* Copying: Backup Copying. Backups can be made by copying or renaming.
\1f
-File: xemacs.info, Node: Dired Deletion, Next: Dired Immed, Prev: Dired Edit, Up: Dired
+File: xemacs.info, Node: Backup Names, Next: Backup Deletion, Prev: Backup, Up: Backup
-Deleting Files With Dired
--------------------------
+Single or Numbered Backups
+..........................
- The primary use of Dired is to flag files for deletion and then
-delete them.
+ If you choose to have a single backup file (the default), the backup
+file's name is constructed by appending `~' to the file name being
+edited; thus, the backup file for `eval.c' is `eval.c~'.
-`d'
- Flag this file for deletion.
+ If you choose to have a series of numbered backup files, backup file
+names are made by appending `.~', the number, and another `~' to the
+original file name. Thus, the backup files of `eval.c' would be called
+`eval.c.~1~', `eval.c.~2~', and so on, through names like
+`eval.c.~259~' and beyond.
-`u'
- Remove deletion-flag on this line.
+ If protection stops you from writing backup files under the usual
+names, the backup file is written as `%backup%~' in your home directory.
+Only one such file can exist, so only the most recently made backup is
+available.
-`<DEL>'
- Remove deletion-flag on previous line, moving point to that line.
+ The choice of single backup or numbered backups is controlled by the
+variable `version-control'. Its possible values are:
-`x'
- Delete the files that are flagged for deletion.
+`t'
+ Make numbered backups.
-`#'
- Flag all auto-save files (files whose names start and end with `#')
- for deletion (*note Auto Save::).
+`nil'
+ Make numbered backups for files that have numbered backups already.
+ Otherwise, make single backups.
-`~'
- Flag all backup files (files whose names end with `~') for deletion
- (*note Backup::).
+`never'
+ Never make numbered backups; always make single backups.
-`. (Period)'
- Flag excess numeric backup files for deletion. The oldest and
- newest few backup files of any one file are exempt; the middle
- ones are flagged.
-
- You can flag a file for deletion by moving to the line describing the
-file and typing `d' or `C-d'. The deletion flag is visible as a `D' at
-the beginning of the line. Point is moved to the beginning of the next
-line, so that repeated `d' commands flag successive files.
-
- The files are flagged for deletion rather than deleted immediately to
-avoid the danger of deleting a file accidentally. Until you direct
-Dired to delete the flagged files, you can remove deletion flags using
-the commands `u' and <DEL>. `u' works just like `d', but removes flags
-rather than making flags. <DEL> moves upward, removing flags; it is
-like `u' with numeric argument automatically negated.
-
- To delete the flagged files, type `x'. This command first displays a
-list of all the file names flagged for deletion, and requests
-confirmation with `yes'. Once you confirm, all the flagged files are
-deleted, and their lines are deleted from the text of the Dired buffer.
-The shortened Dired buffer remains selected. If you answer `no' or
-quit with `C-g', you return immediately to Dired, with the deletion
-flags still present and no files actually deleted.
-
- The `#', `~', and `.' commands flag many files for deletion, based
-on their names. These commands are useful precisely because they do
-not actually delete any files; you can remove the deletion flags from
-any flagged files that you really wish to keep.
-
- `#' flags for deletion all files that appear to have been made by
-auto-saving (that is, files whose names begin and end with `#'). `~'
-flags for deletion all files that appear to have been made as backups
-for files that were edited (that is, files whose names end with `~').
-
- `.' (Period) flags just some of the backup files for deletion: only
-numeric backups that are not among the oldest few nor the newest few
-backups of any one file. Normally `dired-kept-versions' (not
-`kept-new-versions'; that applies only when saving) specifies the
-number of newest versions of each file to keep, and `kept-old-versions'
-specifies the number of oldest versions to keep. Period with a
-positive numeric argument, as in `C-u 3 .', specifies the number of
-newest versions to keep, overriding `dired-kept-versions'. A negative
-numeric argument overrides `kept-old-versions', using minus the value
-of the argument to specify the number of oldest versions of each file
-to keep.
+`version-control' may be set locally in an individual buffer to control
+the making of backups for that buffer's file. For example, Rmail mode
+locally sets `version-control' to `never' to make sure that there is
+only one backup for an Rmail file. *Note Locals::.
projects / chise / xemacs-chise.git / blobdiff