This is Info file ../../info/xemacs.info, produced by Makeinfo-1.63
from the input file xemacs.texi.

   This file documents the XEmacs editor.

   Copyright (C) 1985, 1986, 1988 Richard M. Stallman.  Copyright (C)
1991, 1992, 1993, 1994 Lucid, Inc.  Copyright (C) 1993, 1994 Sun
Microsystems, Inc.  Copyright (C) 1995 Amdahl Corporation.

   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: xemacs.info,  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: xemacs.info,  Node: Version Control,  Next: ListDir,  Prev: Auto Save,  Up: Files

Version Control
===============

   "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.

   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.

* Menu:

* 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.


File: xemacs.info,  Node: Concepts of VC,  Next: Editing with VC,  Prev: Version Control,  Up: Version Control

Concepts of Version Control
---------------------------

   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.

   The file that is maintained under version control is sometimes called
the "work file" corresponding to its master file.

   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.)

   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.

   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').

   A "snapshot" is a coherent collection of versions of the various
files that make up a program.  *Note Snapshots::.


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.


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: 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.

   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 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).

   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'.


File: xemacs.info,  Node: Change Logs and VC,  Next: Old Versions,  Prev: Log Entries,  Up: Version Control

Change Logs and VC
------------------

   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'.


File: xemacs.info,  Node: Old Versions,  Next: VC Status,  Prev: Change Logs and VC,  Up: Version Control

Examining And Comparing Old Versions
------------------------------------

`C-x v ~ VERSION RET'
     Examine version VERSION of the visited file, in a buffer of its
     own (`vc-version-other-window').

`C-x v ='
     Compare the current buffer contents with the latest checked-in
     version of the file.

`C-u C-x v = FILE RET OLDVERS RET NEWVERS RET'
     Compare the specified two versions of FILE.

   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.

   To compare two versions of a file, use the command `C-x v ='
(`vc-diff').

   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.

   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.

   You can specify a checked-in version by its number; you can specify
the most recent checked-in version with an empty version number.

   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'.


File: xemacs.info,  Node: VC Status,  Next: Renaming and VC,  Prev: Old Versions,  Up: Version Control

VC Status Commands
------------------

   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.


File: xemacs.info,  Node: Renaming and VC,  Next: Snapshots,  Prev: VC Status,  Up: Version Control

Renaming VC Work Files and Master Files
---------------------------------------

   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::.).

   You cannot use `vc-rename-file' on a file that is locked by someone
else.


File: xemacs.info,  Node: Snapshots,  Next: Version Headers,  Prev: Renaming and VC,  Up: Version Control

Snapshots
---------

   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.

* Menu:

* Making Snapshots::		The snapshot facilities.
* Snapshot Caveats::		Things to be careful of when using snapshots.


File: xemacs.info,  Node: Making Snapshots,  Next: Snapshot Caveats,  Prev: Snapshots,  Up: Snapshots

Making and Using Snapshots
..........................

   There are two basic commands for snapshots; one makes a snapshot
with a given name, the other retrieves a named snapshot.

`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').

`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').

     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.

   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.

   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.


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: 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: ListDir,  Next: Comparing Files,  Prev: Version Control,  Up: Files

Listing a File Directory
========================

   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).

`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 `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 ``^''.

   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: xemacs.info,  Node: Comparing Files,  Next: Dired,  Prev: ListDir,  Up: Files

Comparing Files
===============

   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.


File: xemacs.info,  Node: Dired,  Next: Misc File Ops,  Prev: Comparing Files,  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 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.

* 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: xemacs.info,  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
d'.


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: 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.

`d'
     Flag this file for deletion.

`u'
     Remove deletion-flag on this line.

`DEL'
     Remove deletion-flag on previous line, moving point to that line.

`x'
     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: xemacs.info,  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.

`c'
     Copies the file described on the current line.  You must supply a
     file name to copy to, using the minibuffer.

`f'
     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::.

`o'
     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::.

`r'
     Renames the file described on the current line.  You must supply a
     file name to rename to, using the minibuffer.

`v'
     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: xemacs.info,  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
NEW.

   `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.
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 previous 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: xemacs.info,  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: xemacs.info,  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-buffer-other-frame' is similar to
`switch-to-buffer' except that it creates a new frame 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: xemacs.info,  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.  A
`*' 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::.).  A `%' indicates a read-only
buffer.  A `.' 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: xemacs.info,  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 it examines an already existing Emacs buffer.  View mode
provides convenient commands for scrolling through the buffer 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 `M-x
append-to-buffer' and `M-x insert-buffer'.  *Note Accumulating Text::.


File: xemacs.info,  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'.

