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[emacs.git] / man / msdog.texi

@c This is part of the Emacs manual.
@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001,
@c   2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Microsoft Windows, Manifesto, Mac OS, Top
@appendix Emacs and Microsoft Windows/MS-DOS
@cindex Microsoft Windows
@cindex MS-Windows, Emacs peculiarities

  This section describes peculiarities of using Emacs on Microsoft
Windows.  Some of these peculiarities are also relevant to Microsoft's
older MS-DOS ``operating system'' (also known as ``MS-DOG'').
However, Emacs features that are relevant @emph{only} to MS-DOS are
described in a separate
@iftex
manual (@pxref{MS-DOS,,, emacs-xtra, Specialized Emacs Features}).
@end iftex
@ifnottex
section (@pxref{MS-DOS}).
@end ifnottex


  The behavior of Emacs on MS-Windows is reasonably similar to what is
documented in the rest of the manual, including support for long file
names, multiple frames, scroll bars, mouse menus, and subprocesses.
However, a few special considerations apply, and they are described
here.

@menu
* Text and Binary::     Text files use CRLF to terminate lines.
* Windows Files::       File-name conventions on Windows.
* ls in Lisp::          Emulation of @code{ls} for Dired.
* Windows HOME::        Where Emacs looks for your @file{.emacs}.
* Windows Keyboard::    Windows-specific keyboard features.
* Windows Mouse::       Windows-specific mouse features.
* Windows Processes::   Running subprocesses on Windows.
* Windows Printing::    How to specify the printer on MS-Windows.
* Windows Misc::        Miscellaneous Windows features.
@ifnottex
* MS-DOS::              Using Emacs on MS-DOS (otherwise known as @dfn{MS-DOG}).
@end ifnottex
@end menu

@node Text and Binary
@section Text Files and Binary Files
@cindex text and binary files on MS-DOS/MS-Windows

  GNU Emacs uses newline characters to separate text lines.  This is the
convention used on GNU, Unix, and other Posix-compliant systems.

@cindex end-of-line conversion on MS-DOS/MS-Windows
  By contrast, MS-DOS and MS-Windows normally use carriage-return linefeed,
a two-character sequence, to separate text lines.  (Linefeed is the same
character as newline.)  Therefore, convenient editing of typical files
with Emacs requires conversion of these end-of-line (EOL) sequences.
And that is what Emacs normally does: it converts carriage-return
linefeed into newline when reading files, and converts newline into
carriage-return linefeed when writing files.  The same mechanism that
handles conversion of international character codes does this conversion
also (@pxref{Coding Systems}).

@cindex cursor location, on MS-DOS
@cindex point location, on MS-DOS
  One consequence of this special format-conversion of most files is
that character positions as reported by Emacs (@pxref{Position Info}) do
not agree with the file size information known to the operating system.

  In addition, if Emacs recognizes from a file's contents that it uses
newline rather than carriage-return linefeed as its line separator, it
does not perform EOL conversion when reading or writing that file.
Thus, you can read and edit files from GNU and Unix systems on MS-DOS
with no special effort, and they will retain their Unix-style
end-of-line convention after you edit them.

  The mode line indicates whether end-of-line translation was used for
the current buffer.  If MS-DOS end-of-line translation is in use for the
buffer, the MS-Windows build of Emacs displays a backslash @samp{\} after
the coding system mnemonic near the beginning of the mode line
(@pxref{Mode Line}).  If no EOL translation was performed, the string
@samp{(Unix)} is displayed instead of the backslash, to alert you that the
file's EOL format is not the usual carriage-return linefeed.

@cindex DOS-to-Unix conversion of files
  To visit a file and specify whether it uses DOS-style or Unix-style
end-of-line, specify a coding system (@pxref{Text Coding}).  For
example, @kbd{C-x @key{RET} c unix @key{RET} C-x C-f foobar.txt}
visits the file @file{foobar.txt} without converting the EOLs; if some
line ends with a carriage-return linefeed pair, Emacs will display
@samp{^M} at the end of that line.  Similarly, you can direct Emacs to
save a buffer in a specified EOL format with the @kbd{C-x @key{RET} f}
command.  For example, to save a buffer with Unix EOL format, type
@kbd{C-x @key{RET} f unix @key{RET} C-x C-s}.  If you visit a file
with DOS EOL conversion, then save it with Unix EOL format, that
effectively converts the file to Unix EOL style, like @code{dos2unix}.

@cindex untranslated file system
@findex add-untranslated-filesystem
  When you use NFS, Samba, or some other similar method to access file
systems that reside on computers using GNU or Unix systems, Emacs
should not perform end-of-line translation on any files in these file
systems---not even when you create a new file.  To request this,
designate these file systems as @dfn{untranslated} file systems by
calling the function @code{add-untranslated-filesystem}.  It takes one
argument: the file system name, including a drive letter and
optionally a directory.  For example,

@example
(add-untranslated-filesystem "Z:")
@end example

@noindent
designates drive Z as an untranslated file system, and

@example
(add-untranslated-filesystem "Z:\\foo")
@end example

@noindent
designates directory @file{\foo} on drive Z as an untranslated file
system.

  Most often you would use @code{add-untranslated-filesystem} in your
@file{.emacs} file, or in @file{site-start.el} so that all the users at
your site get the benefit of it.

@findex remove-untranslated-filesystem
  To countermand the effect of @code{add-untranslated-filesystem}, use
the function @code{remove-untranslated-filesystem}.  This function takes
one argument, which should be a string just like the one that was used
previously with @code{add-untranslated-filesystem}.

  Designating a file system as untranslated does not affect character
set conversion, only end-of-line conversion.  Essentially, it directs
Emacs to create new files with the Unix-style convention of using
newline at the end of a line.  @xref{Coding Systems}.

@vindex file-name-buffer-file-type-alist
@cindex binary files, on MS-DOS/MS-Windows
  Some kinds of files should not be converted at all, because their
contents are not really text.  Therefore, Emacs on MS-Windows distinguishes
certain files as @dfn{binary files}.  (This distinction is not part of
MS-Windows; it is made by Emacs only.)  Binary files include executable
programs, compressed archives, etc.  Emacs uses the file name to decide
whether to treat a file as binary: the variable
@code{file-name-buffer-file-type-alist} defines the file-name patterns
that indicate binary files.  If a file name matches one of the patterns
for binary files (those whose associations are of the type
@code{(@var{pattern} . t)}, Emacs reads and writes that file using the
@code{no-conversion} coding system (@pxref{Coding Systems}) which turns
off @emph{all} coding-system conversions, not only the EOL conversion.
@code{file-name-buffer-file-type-alist} also includes file-name patterns
for files which are known to be Windows-style text files with
carriage-return linefeed EOL format, such as @file{CONFIG.SYS}; Emacs
always writes those files with Windows-style EOLs.

  If a file which belongs to an untranslated file system matches one of
the file-name patterns in @code{file-name-buffer-file-type-alist}, the
EOL conversion is determined by @code{file-name-buffer-file-type-alist}.

@node Windows Files
@section File Names on MS-Windows
@cindex file names on MS-Windows

  MS-Windows and MS-DOS normally use a backslash, @samp{\}, to
separate name units within a file name, instead of the slash used on
other systems.  Emacs on MS-DOS/MS-Windows permits use of either slash or
backslash, and also knows about drive letters in file names.

@cindex file-name completion, on MS-Windows
  On MS-DOS/MS-Windows, file names are case-insensitive, so Emacs by
default ignores letter-case in file names during completion.

@vindex w32-get-true-file-attributes
  If the variable @code{w32-get-true-file-attributes} is
non-@code{nil} (the default), Emacs tries to determine the accurate
link counts for files.  This option is only useful on NTFS volumes,
and it considerably slows down Dired and other features, so use it
only on fast machines.

@node ls in Lisp
@section Emulation of @code{ls} on MS-Windows
@cindex Dired, and MS-Windows/MS-DOS
@cindex @code{ls} emulation

  Dired normally uses the external program @code{ls} (or its close
work-alike) to produce the directory listing displayed in Dired
buffers (@pxref{Dired}).  However, MS-Windows and MS-DOS systems don't
come with such a program, although several ports of @sc{gnu} @code{ls}
are available.  Therefore, Emacs on those systems @emph{emulates}
@code{ls} in Lisp, by using the @file{ls-lisp.el} package.  While
@file{ls-lisp.el} provides a reasonably full emulation of @code{ls},
there are some options and features peculiar to that emulation;
@iftex
for more details, see the documentation of the variables whose names
begin with @code{ls-lisp}.
@end iftex
@ifnottex
they are described in this section.

  The @code{ls} emulation supports many of the @code{ls} switches, but
it doesn't support all of them.  Here's the list of the switches it
does support: @option{-A}, @option{-a}, @option{-B}, @option{-C},
@option{-c}, @option{-i}, @option{-G}, @option{-g}, @option{-R},
@option{-r}, @option{-S}, @option{-s}, @option{-t}, @option{-U},
@option{-u}, and @option{-X}.  The @option{-F} switch is partially
supported (it appends the character that classifies the file, but does
not prevent symlink following).

@vindex ls-lisp-use-insert-directory-program
  On MS-Windows and MS-DOS, @file{ls-lisp.el} is preloaded when Emacs
is built, so the Lisp emulation of @code{ls} is always used on those
platforms.  If you have a ported @code{ls}, setting
@code{ls-lisp-use-insert-directory-program} to a non-@code{nil} value
will revert to using an external program named by the variable
@code{insert-directory-program}.

@vindex ls-lisp-ignore-case
  By default, @file{ls-lisp.el} uses a case-sensitive sort order for
the directory listing it produces; this is so the listing looks the
same as on other platforms.  If you wish that the files be sorted in
case-insensitive order, set the variable @code{ls-lisp-ignore-case} to
a non-@code{nil} value.

@vindex ls-lisp-dirs-first
  By default, files and subdirectories are sorted together, to emulate
the behavior of @code{ls}.  However, native MS-Windows/MS-DOS file
managers list the directories before the files; if you want that
behavior, customize the option @code{ls-lisp-dirs-first} to a
non-@code{nil} value.

@vindex ls-lisp-verbosity
  The variable @code{ls-lisp-verbosity} controls the file attributes
that @file{ls-lisp.el} displays.  The value should be a list that
contains one or more of the symbols @code{links}, @code{uid}, and
@code{gid}.  @code{links} means display the count of different file
names that are associated with (a.k.a.@: @dfn{links to}) the file's
data; this is only useful on NTFS volumes.  @code{uid} means display
the numerical identifier of the user who owns the file.  @code{gid}
means display the numerical identifier of the file owner's group.  The
default value is @code{(links uid gid)} i.e.@: all the 3 optional
attributes are displayed.

@vindex ls-lisp-emulation
  The variable @code{ls-lisp-emulation} controls the flavour of the
@code{ls} emulation by setting the defaults for the 3 options
described above: @code{ls-lisp-ignore-case},
@code{ls-lisp-dirs-first}, and @code{ls-lisp-verbosity}.  The value of
this option can be one of the following symbols:

@table @code
@item GNU
@itemx nil
Emulate @sc{gnu} systems; this is the default.  This sets
@code{ls-lisp-ignore-case} and @code{ls-lisp-dirs-first} to
@code{nil}, and @code{ls-lisp-verbosity} to @code{(links uid gid)}.
@item UNIX
Emulate Unix systems.  Like @code{GNU}, but sets
@code{ls-lisp-verbosity} to @code{(links uid)}.
@item MacOS
Emulate MacOS.  Sets @code{ls-lisp-ignore-case} to @code{t}, and
@code{ls-lisp-dirs-first} and @code{ls-lisp-verbosity} to @code{nil}.
@item MS-Windows
Emulate MS-Windows.  Sets @code{ls-lisp-ignore-case} and
@code{ls-lisp-dirs-first} to @code{t}, and @code{ls-lisp-verbosity} to
@code{(links)} on Windows NT/2K/XP/2K3 and to @code{nil} on Windows 9X.
Note that the default emulation is @emph{not} @code{MS-Windows}, even
on Windows, since many users of Emacs on those platforms prefer the
@sc{gnu} defaults.
@end table

@noindent
Any other value of @code{ls-lisp-emulation} means the same as
@code{GNU}.  Note that this option needs to be set @emph{before}
@file{ls-lisp.el} is loaded, which means that on MS-Windows and MS-DOS
you will have to set the value from your @file{.emacs} file and then
restart Emacs, since @file{ls-lisp.el} is preloaded.

@vindex ls-lisp-support-shell-wildcards
  The variable @code{ls-lisp-support-shell-wildcards} controls how
file-name patterns are supported: if it is non-@code{nil} (the
default), they are treated as shell-style wildcards; otherwise they
are treated as Emacs regular expressions.
@end ifnottex

@node Windows HOME
@section HOME Directory on MS-Windows
@cindex @code{HOME} directory on MS-Windows

  The Windows equivalent of the @code{HOME} directory is the
@dfn{user-specific application data directory}.  The actual location
depends on your Windows version and system configuration; typical values
are @file{C:\Documents and Settings\@var{username}\Application Data} on
Windows 2K/XP and later, and either @file{C:\WINDOWS\Application Data}
or @file{C:\WINDOWS\Profiles\@var{username}\Application Data} on the
older Windows 9X/ME systems.

@cindex init file @file{.emacs} on MS-Windows
  The home directory is where your init file @file{.emacs} is stored.
When Emacs starts, it first checks whether the environment variable
@env{HOME} is set.  If it is, it looks for the init file in the
directory pointed by @env{HOME}.  If @env{HOME} is not defined, Emacs
checks for an existing @file{.emacs} file in @file{C:\}, the root
directory of drive @file{C:}@footnote{
The check in @file{C:\} is in preference to the application data
directory for compatibility with older versions of Emacs, which didn't
check the application data directory.
}.  If there's no such file in @file{C:\}, Emacs next uses the Windows
system calls to find out the exact location of your application data
directory.  If that fails as well, Emacs falls back to @file{C:\}.

  Whatever the final place is, Emacs sets the value of the @env{HOME}
environment variable to point to it, and it will use that location for
other files and directories it normally creates in the user's home
directory.

  You can always find out where Emacs thinks is your home directory's
location by typing @kbd{C-x d ~/ @key{RET}}.  This should present the
list of files in the home directory, and show its full name on the
first line.  Likewise, to visit your init file, type @kbd{C-x C-f
~/.emacs @key{RET}}.

@cindex @file{_emacs} init file, MS-Windows
  Because MS-DOS does not allow file names with leading dots, and
because older Windows systems made it hard to create files with such
names, the Windows port of Emacs supports an alternative name
@file{_emacs} as a fallback, if such a file exists in the home
directory, whereas @file{.emacs} does not.

@node Windows Keyboard
@section Keyboard Usage on MS-Windows
@cindex keyboard, MS-Windows

  This section describes the Windows-specific features related to
keyboard input in Emacs.

@cindex MS-Windows keyboard shortcuts
  Many key combinations (known as ``keyboard shortcuts'') that are in
widespread use in MS-Windows programs are taken by various Emacs
features.  Examples include @kbd{C-C}, @kbd{C-X}, @kbd{C-Z},
@kbd{C-A}, and @kbd{W-SPC}.  You can get some of them back by turning
on CUA Mode (@pxref{CUA Bindings}).

@kindex F10 @r{(MS-Windows)}
@cindex menu bar access using keyboard @r{(MS-Windows)}
  The @key{F10} key on Windows activates the menu bar in a way that
makes it possible to use the menus without a mouse.  In this mode, the
arrow keys traverse the menus, @key{RET} selects a highlighted menu
item, and @key{ESC} closes the menu.

@iftex
@inforef{Windows Keyboard, , emacs}, for information about additional
Windows-specific variables in this category.
@end iftex
@ifnottex
@vindex w32-alt-is-meta
@cindex @code{Alt} key (MS-Windows)
  By default, the key labeled @key{Alt} is mapped as the @key{META}
key.  If you wish it to produce the @code{Alt} modifier instead, set
the variable @code{w32-alt-is-meta} to a @code{nil} value.

@vindex w32-capslock-is-shiftlock
  By default, the @key{CapsLock} key only affects normal character
keys (it converts lower-case characters to their upper-case
variants).  However, if you set the variable
@code{w32-capslock-is-shiftlock} to a non-@code{nil} value, the
@key{CapsLock} key will affect non-character keys as well, as if you
pressed the @key{Shift} key while typing the non-character key.

@vindex w32-enable-caps-lock
  If the variable @code{w32-enable-caps-lock} is set to a @code{nil}
value, the @key{CapsLock} key produces the symbol @code{capslock}
instead of the shifted version of they keys.  The default value is
@code{t}.

@vindex w32-enable-num-lock
@cindex keypad keys (MS-Windows)
  Similarly, if @code{w32-enable-num-lock} is @code{nil}, the
@key{NumLock} key will produce the symbol @code{kp-numlock}.  The
default is @code{t}, which causes @key{NumLock} to work as expected:
toggle the meaning of the keys on the numeric keypad.
@end ifnottex

@vindex w32-apps-modifier
  The variable @code{w32-apps-modifier} controls the effect of the
@key{Apps} key (usually located between the right @key{Alt} and the
right @key{Ctrl} keys).  Its value can be one of the symbols
@code{hyper}, @code{super}, @code{meta}, @code{alt}, @code{control},
or @code{shift} for the respective modifier, or @code{nil} to appear
as the key @code{apps}.  The default is @code{nil}.

@vindex w32-lwindow-modifier
@vindex w32-rwindow-modifier
@vindex w32-scroll-lock-modifier
  The variable @code{w32-lwindow-modifier} determines the effect of
the left Windows key (usually labeled with @key{start} and the Windows
logo).  If its value is @code{nil} (the default), the key will produce
the symbol @code{lwindow}.  Setting it to one of the symbols
@code{hyper}, @code{super}, @code{meta}, @code{alt}, @code{control},
or @code{shift} will produce the respective modifier.  A similar
variable @code{w32-rwindow-modifier} controls the effect of the right
Windows key, and @code{w32-scroll-lock-modifier} does the same for the
@key{ScrLock} key.  If these variables are set to @code{nil}, the
right Windows key produces the symbol @code{rwindow} and @key{ScrLock}
produces the symbol @code{scroll}.

@vindex w32-pass-alt-to-system
@cindex Windows system menu
@cindex @code{Alt} key invokes menu (Windows)
  Emacs compiled as a native Windows application normally turns off
the Windows feature that tapping the @key{ALT} key invokes the Windows
menu.  The reason is that the @key{ALT} serves as @key{META} in Emacs.
When using Emacs, users often press the @key{META} key temporarily and
then change their minds; if this has the effect of bringing up the
Windows menu, it alters the meaning of subsequent commands.  Many
users find this frustrating.

  You can re-enable Windows' default handling of tapping the @key{ALT}
key by setting @code{w32-pass-alt-to-system} to a non-@code{nil}
value.

@ifnottex
@vindex w32-pass-lwindow-to-system
@vindex w32-pass-rwindow-to-system
  The variables @code{w32-pass-lwindow-to-system} and
@code{w32-pass-rwindow-to-system} determine whether the respective
keys are passed to Windows or swallowed by Emacs.  If the value is
@code{nil}, the respective key is silently swallowed by Emacs,
otherwise it is passed to Windows.  The default is @code{t} for both
of these variables.  Passing each of these keys to Windows produces
its normal effect: for example, @kbd{@key{Lwindow}} opens the
@code{Start} menu, etc.@footnote{
Some combinations of the ``Windows'' keys with other keys are caught
by Windows at low level in a way that Emacs currently cannot prevent.
For example, @kbd{@key{Lwindow} r} always pops up the Windows
@samp{Run} dialog.  Customizing the value of
@code{w32-phantom-key-code} might help in some cases, though.}

@vindex w32-recognize-altgr
@kindex AltGr @r{(MS-Windows)}
@cindex AltGr key (MS-Windows)
  The variable @code{w32-recognize-altgr} controls whether the
@key{AltGr} key (if it exists on your keyboard), or its equivalent,
the combination of the right @key{Alt} and left @key{Ctrl} keys
pressed together, is recognized as the @key{AltGr} key.  The default
is @code{t}, which means these keys produce @code{AltGr}; setting it
to @code{nil} causes @key{AltGr} or the equivalent key combination to
be interpreted as the combination of @key{CTRL} and @key{META}
modifiers.
@end ifnottex

@node Windows Mouse
@section Mouse Usage on MS-Windows
@cindex mouse, and MS-Windows

  This section describes the Windows-specific variables related to
mouse.

@vindex w32-mouse-button-tolerance
@cindex simulation of middle mouse button
  The variable @code{w32-mouse-button-tolerance} specifies the
time interval, in milliseconds, for faking middle mouse button press
on 2-button mice.  If both mouse buttons are depressed within this
time interval, Emacs generates a middle mouse button click event
instead of a double click on one of the buttons.

@vindex w32-pass-extra-mouse-buttons-to-system
  If the variable @code{w32-pass-extra-mouse-buttons-to-system} is
non-@code{nil}, Emacs passes the fourth and fifth mouse buttons to
Windows.

@vindex w32-swap-mouse-buttons
  The variable @code{w32-swap-mouse-buttons} controls which of the 3
mouse buttons generates the @kbd{mouse-2} events.  When it is
@code{nil} (the default), the middle button generates @kbd{mouse-2}
and the right button generates @kbd{mouse-3} events.  If this variable
is non-@code{nil}, the roles of these two buttons are reversed.

@node Windows Processes
@section Subprocesses on Windows 9X/ME and Windows NT/2K/XP
@cindex subprocesses on MS-Windows

@cindex DOS applications, running from Emacs
  Emacs compiled as a native Windows application (as opposed to the DOS
version) includes full support for asynchronous subprocesses.
In the Windows version, synchronous and asynchronous subprocesses work
fine on both
Windows 9X/ME and Windows NT/2K/XP as long as you run only 32-bit Windows
applications.  However, when you run a DOS application in a subprocess,
you may encounter problems or be unable to run the application at all;
and if you run two DOS applications at the same time in two
subprocesses, you may have to reboot your system.

Since the standard command interpreter (and most command line utilities)
on Windows 9X are DOS applications, these problems are significant when
using that system.  But there's nothing we can do about them; only
Microsoft can fix them.

If you run just one DOS application subprocess, the subprocess should
work as expected as long as it is ``well-behaved'' and does not perform
direct screen access or other unusual actions.  If you have a CPU
monitor application, your machine will appear to be 100% busy even when
the DOS application is idle, but this is only an artifact of the way CPU
monitors measure processor load.

You must terminate the DOS application before you start any other DOS
application in a different subprocess.  Emacs is unable to interrupt or
terminate a DOS subprocess.  The only way you can terminate such a
subprocess is by giving it a command that tells its program to exit.

If you attempt to run two DOS applications at the same time in separate
subprocesses, the second one that is started will be suspended until the
first one finishes, even if either or both of them are asynchronous.

@cindex kill DOS application
If you can go to the first subprocess, and tell it to exit, the second
subprocess should continue normally.  However, if the second subprocess
is synchronous, Emacs itself will be hung until the first subprocess
finishes.  If it will not finish without user input, then you have no
choice but to reboot if you are running on Windows 9X.  If you are
running on Windows NT/2K/XP, you can use a process viewer application to kill
the appropriate instance of NTVDM instead (this will terminate both DOS
subprocesses).

If you have to reboot Windows 9X in this situation, do not use the
@code{Shutdown} command on the @code{Start} menu; that usually hangs the
system.  Instead, type @kbd{CTL-ALT-@key{DEL}} and then choose
@code{Shutdown}.  That usually works, although it may take a few minutes
to do its job.

@vindex w32-quote-process-args
  The variable @code{w32-quote-process-args} controls how Emacs quotes
the process arguments.  Non-@code{nil} means quote with the @code{"}
character.  If the value is a character, use that character to escape
any quote characters that appear; otherwise chose a suitable escape
character based on the type of the program.

@ifnottex
@findex w32-shell-execute
  The function @code{w32-shell-execute} can be useful for writing
customized commands that run MS-Windows applications registered to
handle a certain standard Windows operation for a specific type of
document or file.  This function is a wrapper around the Windows
@code{ShellExecute} API.  See the MS-Windows API documentation for
more details.
@end ifnottex

@node Windows Printing
@section Printing and MS-Windows

  Printing commands, such as @code{lpr-buffer} (@pxref{Printing}) and
@code{ps-print-buffer} (@pxref{PostScript}) work in MS-DOS and
MS-Windows by sending the output to one of the printer ports, if a
Posix-style @code{lpr} program is unavailable.  The same Emacs
variables control printing on all systems, but in some cases they have
different default values on MS-DOS and MS-Windows.

  Emacs on Windows automatically determines your default printer and
sets the variable @var{printer-name} to that printer's name.  But in
some rare cases this can fail, or you may wish to use a different
printer from within Emacs.  The rest of this section explains how to
tell Emacs which printer to use.

@vindex printer-name@r{, (MS-DOS/MW-Windows)}
  If you want to use your local printer, then set the Lisp variable
@code{lpr-command} to @code{""} (its default value on Windows) and
@code{printer-name} to the name of the printer port---for example,
@code{"PRN"}, the usual local printer port or @code{"LPT2"}, or
@code{"COM1"} for a serial printer.  You can also set
@code{printer-name} to a file name, in which case ``printed'' output
is actually appended to that file.  If you set @code{printer-name} to
@code{"NUL"}, printed output is silently discarded (sent to the system
null device).

  You can also use a printer shared by another machine by setting
@code{printer-name} to the UNC share name for that printer---for
example, @code{"//joes_pc/hp4si"}.  (It doesn't matter whether you use
forward slashes or backslashes here.)  To find out the names of shared
printers, run the command @samp{net view} from the command prompt to
obtain a list of servers, and @samp{net view @var{server-name}} to see
the names of printers (and directories) shared by that server.
Alternatively, click the @samp{Network Neighborhood} icon on your
desktop, and look for machines which share their printers via the
network.

@cindex @samp{net use}, and printing on MS-Windows
@cindex networked printers (MS-Windows)
  If the printer doesn't appear in the output of @samp{net view}, or
if setting @code{printer-name} to the UNC share name doesn't produce a
hardcopy on that printer, you can use the @samp{net use} command to
connect a local print port such as @code{"LPT2"} to the networked
printer.  For example, typing @kbd{net use LPT2: \\joes_pc\hp4si}@footnote{
Note that the @samp{net use} command requires the UNC share name to be
typed with the Windows-style backslashes, while the value of
@code{printer-name} can be set with either forward- or backslashes.}
causes Windows to @dfn{capture} the @code{LPT2} port and redirect the
printed material to the printer connected to the machine @code{joes_pc}.
After this command, setting @code{printer-name} to @code{"LPT2"}
should produce the hardcopy on the networked printer.

  With some varieties of Windows network software, you can instruct
Windows to capture a specific printer port such as @code{"LPT2"}, and
redirect it to a networked printer via the @w{@code{Control
Panel->Printers}} applet instead of @samp{net use}.

  If you set @code{printer-name} to a file name, it's best to use an
absolute file name.  Emacs changes the working directory according to
the default directory of the current buffer, so if the file name in
@code{printer-name} is relative, you will end up with several such
files, each one in the directory of the buffer from which the printing
was done.

  If the value of @code{printer-name} is correct, but printing does
not produce the hardcopy on your printer, it is possible that your
printer does not support printing plain text (some cheap printers omit
this functionality).  In that case, try the PostScript print commands,
described below.

@findex print-buffer @r{(MS-DOS)}
@findex print-region @r{(MS-DOS)}
@vindex lpr-headers-switches @r{(MS-DOS)}
  The commands @code{print-buffer} and @code{print-region} call the
@code{pr} program, or use special switches to the @code{lpr} program, to
produce headers on each printed page.  MS-DOS and MS-Windows don't
normally have these programs, so by default, the variable
@code{lpr-headers-switches} is set so that the requests to print page
headers are silently ignored.  Thus, @code{print-buffer} and
@code{print-region} produce the same output as @code{lpr-buffer} and
@code{lpr-region}, respectively.  If you do have a suitable @code{pr}
program (for example, from GNU Coreutils), set
@code{lpr-headers-switches} to @code{nil}; Emacs will then call
@code{pr} to produce the page headers, and print the resulting output as
specified by @code{printer-name}.

@vindex print-region-function @r{(MS-DOS)}
@cindex lpr usage under MS-DOS
@vindex lpr-command @r{(MS-DOS)}
@vindex lpr-switches @r{(MS-DOS)}
  Finally, if you do have an @code{lpr} work-alike, you can set the
variable @code{lpr-command} to @code{"lpr"}.  Then Emacs will use
@code{lpr} for printing, as on other systems.  (If the name of the
program isn't @code{lpr}, set @code{lpr-command} to specify where to
find it.)  The variable @code{lpr-switches} has its standard meaning
when @code{lpr-command} is not @code{""}.  If the variable
@code{printer-name} has a string value, it is used as the value for the
@code{-P} option to @code{lpr}, as on Unix.

@findex ps-print-buffer @r{(MS-DOS)}
@findex ps-spool-buffer @r{(MS-DOS)}
@vindex ps-printer-name @r{(MS-DOS)}
@vindex ps-lpr-command @r{(MS-DOS)}
@vindex ps-lpr-switches @r{(MS-DOS)}
  A parallel set of variables, @code{ps-lpr-command},
@code{ps-lpr-switches}, and @code{ps-printer-name} (@pxref{PostScript
Variables}), defines how PostScript files should be printed.  These
variables are used in the same way as the corresponding variables
described above for non-PostScript printing.  Thus, the value of
@code{ps-printer-name} is used as the name of the device (or file) to
which PostScript output is sent, just as @code{printer-name} is used
for non-PostScript printing.  (There are two distinct sets of
variables in case you have two printers attached to two different
ports, and only one of them is a PostScript printer.)

  The default value of the variable @code{ps-lpr-command} is @code{""},
which causes PostScript output to be sent to the printer port specified
by @code{ps-printer-name}, but @code{ps-lpr-command} can also be set to
the name of a program which will accept PostScript files.  Thus, if you
have a non-PostScript printer, you can set this variable to the name of
a PostScript interpreter program (such as Ghostscript).  Any switches
that need to be passed to the interpreter program are specified using
@code{ps-lpr-switches}.  (If the value of @code{ps-printer-name} is a
string, it will be added to the list of switches as the value for the
@code{-P} option.  This is probably only useful if you are using
@code{lpr}, so when using an interpreter typically you would set
@code{ps-printer-name} to something other than a string so it is
ignored.)

  For example, to use Ghostscript for printing on the system's default
printer, put this in your @file{.emacs} file:

@example
(setq ps-printer-name t)
(setq ps-lpr-command "D:/gs6.01/bin/gswin32c.exe")
(setq ps-lpr-switches '("-q" "-dNOPAUSE" "-dBATCH"
                        "-sDEVICE=mswinpr2"
                        "-sPAPERSIZE=a4"))
@end example

@noindent
(This assumes that Ghostscript is installed in the
@file{D:/gs6.01} directory.)

@node Windows Misc
@section Miscellaneous Windows-specific features

  This section describes miscellaneous Windows-specific features.

@vindex w32-use-visible-system-caret
@cindex screen reader software, MS-Windows
  The variable @code{w32-use-visible-system-caret} is a flag that
determines whether to make the system caret visible.  The default is
@code{nil}, which means Emacs draws its own cursor to indicate the
position of point.  A non-@code{nil} value means Emacs will indicate
point location by the system caret; this facilitates use of screen
reader software.  When this variable is non-@code{nil}, other
variables affecting the cursor display have no effect.

@iftex
@inforef{Windows Misc, , emacs}, for information about additional
Windows-specific variables in this category.
@end iftex

@ifnottex
@vindex w32-grab-focus-on-raise
@cindex frame focus policy, MS-Windows
  The variable @code{w32-grab-focus-on-raise}, if set to a
non-@code{nil} value causes a frame to grab focus when it is raised.
The default is @code{t}, which fits well with the Windows default
click-to-focus policy.

@vindex w32-list-proportional-fonts
  The variable @code{w32-list-proportional-fonts} controls whether
proportional fonts are included in the font selection dialog.  If its
value is non-@code{nil}, these fonts will be included.  The default is
@code{nil}.
@end ifnottex

@ifnottex
@include msdog-xtra.texi
@end ifnottex

@ignore
   arch-tag: f39d2590-5dcc-4318-88d9-0eb73ca10fa2
@end ignore