The CICA Windows Explosion!/The CICA Windows Explosion! - Disc 2.iso/demo/wemdemo4.zip/INFO/LEMACS.6

GNU Info File | 1994-09-21 | 52KB | 858 lines

This is Info file ../info/lemacs, produced by Makeinfo-1.55 from the
input file lemacs.txi.
   This file documents the GNU Emacs editor.
   Copyright (C) 1985, 1986, 1988 Richard M. Stallman.  Copyright (C)
1991, 1992 Lucid, Inc.
   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the sections entitled "The GNU Manifesto", "Distribution" and "GNU
General Public License" are included exactly as in the original, and
provided that the entire resulting derived work is distributed under the
terms of a permission notice identical to this one.
   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that the sections entitled "The GNU Manifesto",
"Distribution" and "GNU General Public License" may be included in a
translation approved by the author instead of in the original English.
File: lemacs,  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.
   "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, 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 Lucid GNU Emacs under X, you can also use the
Open File... 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.
   You can display a file in a new screen by using the function
`find-file-new-screen'. This function is similar to `find-file' except
that it creates a new screen in which the file is displayed.
   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 hard-link or symbolic-link to a file that is
already in a buffer, the existing buffer will be found instead of a
newly created one.
   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::.
   Use the function `find-this-file-other-window' to edit a file
mentioned in the buffer yuou are editing or to test if that file exists.
To do 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' abd 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.
File: lemacs,  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
     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 written)
   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-write-file-hooks' to list all
the functions to be called after writing out a buffer to a file.
* Menu:
* Backup::       How Emacs saves the old version of your file.
* Interlocking:: How Emacs protects against simultaneous editing
                  of one file by two users.
File: lemacs,  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.  (Provided 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.
File: lemacs,  Node: Backup Names,  Next: Backup Deletion,  Prev: Backup,  Up: Backup
Single or Numbered Backups
..........................
   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~'.
   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.
   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.
   The choice of single backup or numbered backups is controlled by the
variable `version-control'.  Its possible values are
     Make numbered backups.
`nil'
     Make numbered backups for files that have numbered backups already.
     Otherwise, make single backups.
`never'
     Never make numbered backups; always make single backups.
`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::.
File: lemacs,  Node: Backup Deletion,  Next: Backup Copying,  Prev: Backup Names,  Up: Backup
Automatic Deletion of Backups
.............................
   To prevent unlimited consumption of disk space, Emacs can delete
numbered backup versions automatically.  Generally Emacs keeps the
first few backups and the latest few backups, deleting any in between.
This happens every time a new backup is made.  The two variables that
control the deletion are `kept-old-versions' and `kept-new-versions'.
Their values are, respectively the number of oldest (lowest-numbered)
backups to keep and the number of newest (highest-numbered) ones to
keep, each time a new backup is made.  The values are used just after a
new backup version is made; that newly made backup is included in the
count in `kept-new-versions'.  By default, both variables are 2.
   If `trim-versions-without-asking' is non-`nil',  excess middle
versions are deleted without notification.  If it is `nil', the
default, you are asked whether the excess middle versions should really
be deleted.
   You can also use Dired's `.' (Period) command to delete old versions.
*Note Dired::.
File: lemacs,  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 always shows who last edited the file.  The owners of the backups
show who produced them.  Occasionally there is a file whose owner
should not change.  Since most files` owner should change, 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 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: lemacs,  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:
     Steal the lock.  Whoever was already changing the file loses the
     lock, and you get the lock.
     Proceed.  Go ahead and edit the file despite its being locked by
     someone else.
     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 her 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-mode' to set the UNIX `umask' value to the NMASK
argument. The `umask' value is the default protection mode for new
files.
File: lemacs,  Node: Reverting,  Next: Auto Save,  Prev: Saving,  Up: Files
Reverting a Buffer
==================
   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.
File: lemacs,  Node: Auto Save,  Next: ListDir,  Prev: Reverting,  Up: Files
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.
* Menu:
* Files: Auto Save Files.
* Control: Auto Save Control.
* Recover::        Recovering text from auto-save files.
File: lemacs,  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.
File: lemacs,  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.  A value of zero or `nil' means 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)'.
File: lemacs,  Node: Recover,  Prev: Auto Save Control,  Up: Auto Save
Recovering Data from Auto-Saves
-------------------------------
   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:
     M-x recover-file RET foo.c RET
     C-x C-s
   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.
   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'.
File: lemacs,  Node: ListDir,  Next: Dired,  Prev: Auto Save,  Up: Files
Listing a File Directory
========================
   Files are classified 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).
`C-x C-d DIR-OR-PATTERN'
     Print a brief directory listing (`list-directory').
`C-u C-x C-d DIR-OR-PATTERN'
     Print a verbose directory listing.
   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,
     C-x C-d /u2/emacs/etc RET
lists all the files in directory `/u2/emacs/etc'.  An example of
specifying a file name pattern is
     C-x C-d /u2/emacs/src/*.c RET
   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').
   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).
   The variable `diretory-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 ``^''.
   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.
File: lemacs,  Node: Dired,  Next: Misc File Ops,  Prev: ListDir,  Up: Files
Dired, the Directory Editor
===========================
   Dired makes it easy to delete or visit many of the files in a single
directory at once.  It makes 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.
* 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: lemacs,  Node: Dired Enter,  Next: Dired Edit,  Prev: Dired,  Up: Dired
Entering Dired
--------------
   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'.
   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
File: lemacs,  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" the 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: lemacs,  Node: Dired Deletion,  Next: Dired Immed,  Prev: Dired Edit,  Up: Dired
Deleting Files with Dired
-------------------------
   The primary use of Dired is to flag files for deletion and then
delete them.
     Flag this file for deletion.
     Remove deletion-flag on this line.
`DEL'
     Remove deletion-flag on previous line, moving point to that line.
     Delete the files that are flagged for deletion.
     Flag all auto-save files (files whose names start and end with `#')
     for deletion (*note Auto Save::.).
     Flag all backup files (files whose names end with `~') for deletion
     (*note Backup::.).
`. (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.
File: lemacs,  Node: Dired Immed,  Prev: Dired Deletion,  Up: Dired
Immediate File Operations in Dired
----------------------------------
   Some file operations in Dired take place immediately when they are
requested.
     Copies the file described on the current line.  You must supply a
     file name to copy to, using the minibuffer.
     Visits the file described on the current line.  It is just like
     typing `C-x C-f' and supplying that file name.  If the file on
     this line is a subdirectory, `f' actually causes Dired to be
     invoked on that subdirectory.  *Note Visiting::.
     Like `f', but uses another window to display the file's buffer.
     The Dired buffer remains visible in the first window.  This is
     like using `C-x 4 C-f' to visit the file.  *Note Windows::.
     Renames the file described on the current line.  You must supply a
     file name to rename to, using the minibuffer.
     Views the file described on this line using `M-x view-file'.
     Viewing a file is like visiting it, but is slanted toward moving
     around in the file conveniently and does not allow changing the
     file.  *Note View File: Misc File Ops.  Viewing a file that is a
     directory runs Dired on that directory.
File: lemacs,  Node: Misc File Ops,  Prev: Dired,  Up: Files
Miscellaneous File Operations
=============================
   Emacs has commands for performing many other operations on files.
All operate on one file; they do not accept wildcard file names.
   You can use the command `M-x add-name-to-file' to add a name to an
existing file without removing the old name.  The new name must belong
on the file system that the file is on.
   `M-x append-to-file' adds the text of the region to the end of the
specified file.
   `M-x copy-file' reads the file OLD and writes a new file named NEW
with the same contents.  Confirmation is required if a file named NEW
already exists, because copying overwrites the old contents of the file
   `M-x delete-file' deletes a specified file, like the `rm' command in
the shell.  If you are deleting many files in one directory, it may be
more convenient to use Dired (*note Dired::.).
   `M-x insert-file' inserts a copy of the contents of a specified file
into the current buffer at point, leaving point unchanged before the
contents and the mark after them.  *Note Mark::.
   `M-x make-symbolic-link' reads two file names OLD and LINKNAME, and
then creates a symbolic link named LINKNAME and pointing at OLD.  The
future attempts to open file LINKNAME will then refer to the file named
OLD at the time the opening is done, or will result in an error if the
name OLD is not in use at that time.  Confirmation is required if you
create the link while LINKNAME is in use.  Note that not all systems
support symbolic links.
   `M-x rename-file' reads two file names OLD and NEW using the
minibuffer, then renames file OLD as NEW.  If a file named NEW already
exists, you must confirm with `yes' or renaming is not done; this is
because renaming causes the old meaning of the name NEW to be lost.  If
OLD and NEW are on different file systems, the file OLD is copied and
deleted.
   `M-x view-file' allows you to scan or read a file by sequential
screenfuls.  It reads a file name argument using the minibuffer.  After
reading the file into an Emacs buffer, `view-file' reads and displays
one windowful.  You can then type SPC to scroll forward one window, or
DEL to scroll backward.  Various other commands are provided for moving
around in the file, but none for changing it; type `C-h' while viewing
a file for a list of them.  Most commands are the default Emacs cursor
motion commands.  To exit from viewing, type `C-c'.
File: lemacs,  Node: Buffers,  Next: Windows,  Prev: Files,  Up: Top
Using Multiple Buffers
**********************
   Text you are editing in Emacs resides in an object called a
"buffer".  Each time you visit a file, Emacs creates a buffer to hold
the file's text.  Each time you invoke Dired, Emacs creates a buffer to
hold the directory listing.  If you send a message with `C-x m', a
buffer named `*mail*' is used to hold the text of the message.  When
you ask for a command's documentation, it appears in a buffer called
`*Help*'.
   At any time, one and only one buffer is "selected".  It is also
called the "current buffer".  Saying a command operates on "the buffer"
really means that the command operates on the selected buffer, as most
commands do.
   When Emacs creates multiple windows, each window has a chosen buffer
which is displayed there, but at any time only one of the windows is
selected and its chosen buffer is the selected buffer.  Each window's
mode line displays the name of the buffer the window is displaying
(*note Windows::.).
   Each buffer has a name which can be of any length but is
case-sensitive.  You can select a buffer using its name.  Most buffers
are created when you visit files; their names are derived from the
files' names.  You can also create an empty buffer with any name you
want.  A newly started Emacs has a buffer named `*scratch*' which you
can use for evaluating Lisp expressions in Emacs.
   Each buffer records what file it is visiting, whether it is
modified, and what major mode and minor modes are in effect in it
(*note Major Modes::.).  Any Emacs variable can be made "local to" a
particular buffer, meaning its value in that buffer can be different
from the value in other buffers.  *Note Locals::.
* Menu:
* Select Buffer::   Creating a new buffer or reselecting an old one.
* List Buffers::    Getting a list of buffers that exist.
* Misc Buffer::     Renaming; changing read-onliness; copying text.
* Kill Buffer::     Killing buffers you no longer need.
* Several Buffers:: How to go through the list of all buffers
                     and operate variously on several of them.
File: lemacs,  Node: Select Buffer,  Next: List Buffers,  Prev: Buffers,  Up: Buffers
Creating and Selecting Buffers
==============================
`C-x b BUFFER RET'
     Select or create a buffer named BUFFER (`switch-to-buffer').
`C-x 4 b BUFFER RET'
     Similar but select a buffer named BUFFER in another window
     (`switch-to-buffer-other-window').
`M-x switch-to-other-buffer N'
     Switch to the previous buffer.
   To select a buffer named BUFNAME, type `C-x b BUFNAME RET'.  This is
the command `switch-to-buffer' with argument BUFNAME.  You can use
completion on an abbreviation for the buffer name you want (*note
Completion::.).  An empty argument to `C-x b' specifies the most
recently selected buffer that is not displayed in any window.
   Most buffers are created when you visit files, or use Emacs commands
that display text.  You can also create a buffer explicitly by typing
`C-x b BUFNAME RET', which creates a new, empty buffer that is not
visiting any file, and selects it for editing.  The new buffer's major
mode is determined by the value of `default-major-mode' (*note Major
Modes::.).  Buffers not visiting files are usually used for making
notes to yourself.  If you try to save one, you are asked for the file
name to use.
   The function `switch-to-bufer-new-screen' is similar to
`switch-to-buffer' except that it creates a new screen in which to
display the selected buffer.
   Use `M-x switch-to-other-buffer' to visit the previous buffer. If
you supply a positive integer N, the Nth most recent buffer is
displayed. If you supply an argument of 0, the current buffer is moved
to the bottom of the buffer stack.
   Note that you can also use `C-x C-f' and any other command for
visiting a file to switch buffers.  *Note Visiting::.
File: lemacs,  Node: List Buffers,  Next: Misc Buffer,  Prev: Select Buffer,  Up: Buffers
Listing Existing Buffers
========================
`C-x C-b'
     List the existing buffers (`list-buffers').
   To print a list of all existing buffers, type `C-x C-b'.  Each line
in the list shows one buffer's name, major mode and visited file.  `*'
at the beginning of a line indicates the buffer has been "modified".
If several buffers are modified, it may be time to save some with `C-x
s' (*note Saving::.).  `%' indicates a read-only buffer.  `.' marks the
selected buffer.  Here is an example of a buffer list:
      MR Buffer         Size  Mode           File
      -- ------         ----  ----           ----
     .*  emacs.tex      383402 Texinfo       /u2/emacs/man/emacs.tex
         *Help*         1287  Fundamental
         files.el       23076 Emacs-Lisp     /u2/emacs/lisp/files.el
       % RMAIL          64042 RMAIL          /u/rms/RMAIL
      *% man            747   Dired        /u2/emacs/man/
         net.emacs      343885 Fundamental   /u/rms/net.emacs
         fileio.c       27691 C              /u2/emacs/src/fileio.c
         NEWS           67340 Text           /u2/emacs/etc/NEWS
         *scratch*       0     Lisp Interaction
Note that the buffer `*Help*' was made by a help request; it is not
visiting any file.  The buffer `man' was made by Dired on the directory
`/u2/emacs/man/'.
   As you move the mouse over the `*Buffer List*' buffer, the lines are
highlighted.  This visual cue indicates that clicking the right mouse
button (`button3') will pop up a menu of commands on the buffer
represented by this line.  This menu duplicates most of those commands
which are bound to keys in the `*Buffer List*' buffer.
File: lemacs,  Node: Misc Buffer,  Next: Kill Buffer,  Prev: List Buffers,  Up: Buffers
Miscellaneous Buffer Operations
===============================
`C-x C-q'
     Toggle read-only status of buffer (`toggle-read-only').
`M-x rename-buffer'
     Change the name of the current buffer.
`M-x view-buffer'
     Scroll through a buffer.
   A buffer can be "read-only", which means that commands to change its
text are not allowed.  Normally, read-only buffers are created by
subsystems such as Dired and Rmail that have special commands to operate
on the text.  Emacs also creates a read-only buffer if you visit a file
that is protected.  To make changes in a read-only buffer, use the
command `C-x C-q' (`toggle-read-only').  It makes a read-only buffer
writable, and makes a writable buffer read-only.  This works by setting
the variable `buffer-read-only', which has a local value in each buffer
and makes a buffer read-only if its value is non-`nil'.
   `M-x rename-buffer' changes the name of the current buffer,
prompting for the new name in the minibuffer.  There is no default.  If
you specify a name that is used by a different buffer, an error is
signalled and renaming is not done.
   `M-x view-buffer' is similar to `M-x view-file' (*note Misc File
Ops::.) but examines an already existing Emacs buffer.  View mode
provides commands for scrolling through the buffer conveniently but not
for changing it.  When you exit View mode, the resulting value of point
remains in effect.
   To copy text from one buffer to another, use the commands `C-x a'
(`append-to-buffer') and `M-x insert-buffer'.  *Note Accumulating
Text::.
File: lemacs,  Node: Kill Buffer,  Next: Several Buffers,  Prev: Misc Buffer,  Up: Buffers
Killing Buffers
===============
   After using Emacs for a while, you may accumulate a large number of
buffers, and may want to eliminate the ones you no longer need.  There
are several commands for doing this.
`C-x k'
     Kill a buffer, specified by name (`kill-buffer').
`M-x kill-some-buffers'
     Offer to kill each buffer, one by one.
   `C-x k' (`kill-buffer') kills one buffer, whose name you specify in
the minibuffer.  If you type just RET in the minibuffer, the default,
killing the current buffer, is used.  If the current buffer is killed,
the buffer that has been selected recently but does not appear in any
window now is selected.  If the buffer being killed contains unsaved
changes you are asked to confirm with `yes' before the buffer is killed.
   The command `M-x kill-some-buffers' asks about each buffer, one by
one.  An answer of `y' means to kill the buffer.  Killing the current
buffer or a buffer containing unsaved changes selects a new buffer or
asks for confirmation just like `kill-buffer'.