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688 lines
29 KiB
Plaintext
@c This is part of the Emacs manual.
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@c Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc.
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@c See file emacs.texi for copying conditions.
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@c
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@c This file is included either in emacs-xtra.texi (when producing the
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@c printed version) or in the main Emacs manual (for the on-line version).
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@node MS-DOS
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@section Emacs and MS-DOS
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@cindex MS-DOG
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@cindex MS-DOS peculiarities
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This section briefly describes the peculiarities of using Emacs on
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the MS-DOS ``operating system'' (also known as ``MS-DOG'').
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@iftex
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Information about Emacs and Microsoft's current operating system
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Windows (also known as ``Losedows) is in the main Emacs manual
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(@pxref{Microsoft Systems,,, emacs, the Emacs Manual}).
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@end iftex
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@ifnottex
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Information about peculiarities common to MS-DOS and Microsoft's
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current operating systems Windows (also known as ``Losedows) is in
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@ref{Microsoft Windows}.
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@end ifnottex
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If you build Emacs for MS-DOS, the binary will also run on Windows
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3.X, Windows NT, Windows 9X/ME, Windows 2000/XP, or OS/2 as a DOS
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application; all of this chapter applies for all of those systems, if
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you use an Emacs that was built for MS-DOS.
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@iftex
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@xref{Text and Binary,,,emacs, the Emacs Manual}, for information
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@end iftex
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@ifnottex
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@xref{Text and Binary}, for information
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@end ifnottex
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about Emacs' special handling of text files under MS-DOS (and Windows).
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@menu
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* Keyboard: MS-DOS Keyboard. Keyboard conventions on MS-DOS.
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* Mouse: MS-DOS Mouse. Mouse conventions on MS-DOS.
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* Display: MS-DOS Display. Fonts, frames and display size on MS-DOS.
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* Files: MS-DOS File Names. File name conventions on MS-DOS.
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* Printing: MS-DOS Printing. Printing specifics on MS-DOS.
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* I18N: MS-DOS and MULE. Support for internationalization on MS-DOS.
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* Processes: MS-DOS Processes. Running subprocesses on MS-DOS.
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@end menu
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@node MS-DOS Keyboard
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@subsection Keyboard Usage on MS-DOS
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@kindex DEL @r{(MS-DOS)}
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@kindex BS @r{(MS-DOS)}
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The key that is called @key{DEL} in Emacs (because that's how it is
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designated on most workstations) is known as @key{BS} (backspace) on a
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PC. That is why the PC-specific terminal initialization remaps the
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@key{BS} key to act as @key{DEL}; the @key{DELETE} key is remapped to act
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as @kbd{C-d} for the same reasons.
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@kindex C-g @r{(MS-DOS)}
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@kindex C-BREAK @r{(MS-DOS)}
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@cindex quitting on MS-DOS
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Emacs built for MS-DOS recognizes @kbd{C-@key{BREAK}} as a quit
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character, just like @kbd{C-g}. This is because Emacs cannot detect
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that you have typed @kbd{C-g} until it is ready for more input. As a
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consequence, you cannot use @kbd{C-g} to stop a running command
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@iftex
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(@pxref{Quitting,,,emacs, the Emacs Manual}).
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@end iftex
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@ifnottex
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(@pxref{Quitting}).
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@end ifnottex
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By contrast, @kbd{C-@key{BREAK}} @emph{is} detected as soon as you
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type it (as @kbd{C-g} is on other systems), so it can be used to stop
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a running command and for emergency escape
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@iftex
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(@pxref{Emergency Escape,,,emacs, the Emacs Manual}).
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@end iftex
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@ifnottex
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(@pxref{Emergency Escape}).
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@end ifnottex
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@cindex Meta (under MS-DOS)
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@cindex Hyper (under MS-DOS)
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@cindex Super (under MS-DOS)
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@vindex dos-super-key
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@vindex dos-hyper-key
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The PC keyboard maps use the left @key{ALT} key as the @key{META} key.
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You have two choices for emulating the @key{SUPER} and @key{HYPER} keys:
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choose either the right @key{CTRL} key or the right @key{ALT} key by
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setting the variables @code{dos-hyper-key} and @code{dos-super-key} to 1
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or 2 respectively. If neither @code{dos-super-key} nor
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@code{dos-hyper-key} is 1, then by default the right @key{ALT} key is
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also mapped to the @key{META} key. However, if the MS-DOS international
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keyboard support program @file{KEYB.COM} is installed, Emacs will
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@emph{not} map the right @key{ALT} to @key{META}, since it is used for
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accessing characters like @kbd{~} and @kbd{@@} on non-US keyboard
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layouts; in this case, you may only use the left @key{ALT} as @key{META}
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key.
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@kindex C-j @r{(MS-DOS)}
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@vindex dos-keypad-mode
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The variable @code{dos-keypad-mode} is a flag variable that controls
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what key codes are returned by keys in the numeric keypad. You can also
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define the keypad @key{ENTER} key to act like @kbd{C-j}, by putting the
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following line into your @file{_emacs} file:
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@smallexample
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;; @r{Make the @key{ENTER} key from the numeric keypad act as @kbd{C-j}.}
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(define-key function-key-map [kp-enter] [?\C-j])
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@end smallexample
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@node MS-DOS Mouse
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@subsection Mouse Usage on MS-DOS
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@cindex mouse support under MS-DOS
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Emacs on MS-DOS supports a mouse (on the default terminal only).
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The mouse commands work as documented, including those that use menus
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and the menu bar
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@iftex
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(@pxref{Menu Bar,,,emacs, the Emacs Manual}).
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@end iftex
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@ifnottex
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(@pxref{Menu Bar}).
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@end ifnottex
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Scroll bars don't work in MS-DOS Emacs. PC mice usually have only
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two buttons; these act as @kbd{Mouse-1} and @kbd{Mouse-2}, but if you
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press both of them together, that has the effect of @kbd{Mouse-3}. If
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the mouse does have 3 buttons, Emacs detects that at startup, and all
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the 3 buttons function normally, as on X.
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Help strings for menu-bar and pop-up menus are displayed in the echo
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area when the mouse pointer moves across the menu items. Highlighting
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of mouse-sensitive text
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@iftex
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(@pxref{Mouse References,,,emacs, the Emacs Manual})
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@end iftex
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@ifnottex
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(@pxref{Mouse References})
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@end ifnottex
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is also supported.
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@cindex mouse, set number of buttons
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@findex msdos-set-mouse-buttons
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Some versions of mouse drivers don't report the number of mouse
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buttons correctly. For example, mice with a wheel report that they
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have 3 buttons, but only 2 of them are passed to Emacs; the clicks on
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the wheel, which serves as the middle button, are not passed. In
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these cases, you can use the @kbd{M-x msdos-set-mouse-buttons} command
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to tell Emacs how many mouse buttons to expect. You could make such a
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setting permanent by adding this fragment to your @file{_emacs} init
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file:
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@example
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;; @r{Treat the mouse like a 2-button mouse.}
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(msdos-set-mouse-buttons 2)
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@end example
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@cindex Windows clipboard support
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Emacs built for MS-DOS supports clipboard operations when it runs on
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Windows. Commands that put text on the kill ring, or yank text from
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the ring, check the Windows clipboard first, just as Emacs does on the
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X Window System
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@iftex
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(@pxref{Mouse Commands,,,emacs, the Emacs Manual}).
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@end iftex
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@ifnottex
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(@pxref{Mouse Commands}).
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@end ifnottex
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Only the primary selection and the cut buffer are supported by MS-DOS
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Emacs on Windows; the secondary selection always appears as empty.
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Due to the way clipboard access is implemented by Windows, the
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length of text you can put into the clipboard is limited by the amount
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of free DOS memory that is available to Emacs. Usually, up to 620KB of
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text can be put into the clipboard, but this limit depends on the system
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configuration and is lower if you run Emacs as a subprocess of
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another program. If the killed text does not fit, Emacs outputs a
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message saying so, and does not put the text into the clipboard.
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Null characters also cannot be put into the Windows clipboard. If the
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killed text includes null characters, Emacs does not put such text into
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the clipboard, and displays in the echo area a message to that effect.
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@vindex dos-display-scancodes
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The variable @code{dos-display-scancodes}, when non-@code{nil},
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directs Emacs to display the @acronym{ASCII} value and the keyboard scan code of
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each keystroke; this feature serves as a complement to the
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@code{view-lossage} command, for debugging.
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@node MS-DOS Display
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@subsection Display on MS-DOS
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@cindex faces under MS-DOS
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@cindex fonts, emulating under MS-DOS
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Display on MS-DOS cannot use font variants, like bold or italic, but
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it does support multiple faces, each of which can specify a foreground
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and a background color. Therefore, you can get the full functionality
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of Emacs packages that use fonts (such as @code{font-lock}, Enriched
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Text mode, and others) by defining the relevant faces to use different
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colors. Use the @code{list-colors-display} command
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@iftex
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(@pxref{Frame Parameters,,,emacs, the Emacs Manual})
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@end iftex
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@ifnottex
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(@pxref{Frame Parameters})
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@end ifnottex
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and the @code{list-faces-display} command
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@iftex
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(@pxref{Faces,,,emacs, the Emacs Manual})
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@end iftex
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@ifnottex
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(@pxref{Faces})
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@end ifnottex
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to see what colors and faces are available and what they look like.
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@xref{MS-DOS and MULE}, later in this chapter, for information on
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how Emacs displays glyphs and characters that aren't supported by the
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native font built into the DOS display.
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@cindex cursor shape on MS-DOS
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When Emacs starts, it changes the cursor shape to a solid box. This
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is for compatibility with other systems, where the box cursor is the
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default in Emacs. This default shape can be changed to a bar by
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specifying the @code{cursor-type} parameter in the variable
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@code{default-frame-alist}
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@iftex
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(@pxref{Creating Frames,,,emacs, the Emacs Manual}).
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@end iftex
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@ifnottex
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(@pxref{Creating Frames}).
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@end ifnottex
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The MS-DOS terminal doesn't support a vertical-bar cursor,
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so the bar cursor is horizontal, and the @code{@var{width}} parameter,
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if specified by the frame parameters, actually determines its height.
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For this reason, the @code{bar} and @code{hbar} cursor types produce
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the same effect on MS-DOS. As an extension, the bar cursor
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specification can include the starting scan line of the cursor as well
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as its width, like this:
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@example
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'(cursor-type bar @var{width} . @var{start})
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@end example
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@noindent
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In addition, if the @var{width} parameter is negative, the cursor bar
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begins at the top of the character cell.
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@cindex frames on MS-DOS
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The MS-DOS terminal can only display a single frame at a time. The
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Emacs frame facilities work on MS-DOS much as they do on text-only
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terminals
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@iftex
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(@pxref{Frames,,,emacs, the Emacs Manual}).
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@end iftex
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@ifnottex
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(@pxref{Frames}).
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@end ifnottex
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When you run Emacs from a DOS window on MS-Windows, you can make the
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visible frame smaller than the full screen, but Emacs still cannot
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display more than a single frame at a time.
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@cindex frame size under MS-DOS
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@findex mode4350
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@findex mode25
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The @code{mode4350} command switches the display to 43 or 50
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lines, depending on your hardware; the @code{mode25} command switches
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to the default 80x25 screen size.
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By default, Emacs only knows how to set screen sizes of 80 columns by
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25, 28, 35, 40, 43 or 50 rows. However, if your video adapter has
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special video modes that will switch the display to other sizes, you can
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have Emacs support those too. When you ask Emacs to switch the frame to
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@var{n} rows by @var{m} columns dimensions, it checks if there is a
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variable called @code{screen-dimensions-@var{n}x@var{m}}, and if so,
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uses its value (which must be an integer) as the video mode to switch
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to. (Emacs switches to that video mode by calling the BIOS @code{Set
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Video Mode} function with the value of
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@code{screen-dimensions-@var{n}x@var{m}} in the @code{AL} register.)
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For example, suppose your adapter will switch to 66x80 dimensions when
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put into video mode 85. Then you can make Emacs support this screen
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size by putting the following into your @file{_emacs} file:
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@example
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(setq screen-dimensions-66x80 85)
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@end example
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Since Emacs on MS-DOS can only set the frame size to specific
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supported dimensions, it cannot honor every possible frame resizing
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request. When an unsupported size is requested, Emacs chooses the next
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larger supported size beyond the specified size. For example, if you
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ask for 36x80 frame, you will get 40x80 instead.
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The variables @code{screen-dimensions-@var{n}x@var{m}} are used only
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when they exactly match the specified size; the search for the next
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larger supported size ignores them. In the above example, even if your
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VGA supports 38x80 dimensions and you define a variable
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@code{screen-dimensions-38x80} with a suitable value, you will still get
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40x80 screen when you ask for a 36x80 frame. If you want to get the
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38x80 size in this case, you can do it by setting the variable named
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@code{screen-dimensions-36x80} with the same video mode value as
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@code{screen-dimensions-38x80}.
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Changing frame dimensions on MS-DOS has the effect of changing all the
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other frames to the new dimensions.
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@node MS-DOS File Names
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@subsection File Names on MS-DOS
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@cindex file names under MS-DOS
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@cindex init file, default name under MS-DOS
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On MS-DOS, file names are case-insensitive and limited to eight
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characters, plus optionally a period and three more characters. Emacs
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knows enough about these limitations to handle file names that were
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meant for other operating systems. For instance, leading dots
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@samp{.} in file names are invalid in MS-DOS, so Emacs transparently
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converts them to underscores @samp{_}; thus your default init file
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@iftex
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(@pxref{Init File,,,emacs, the Emacs Manual})
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@end iftex
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@ifnottex
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(@pxref{Init File})
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@end ifnottex
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is called @file{_emacs} on MS-DOS. Excess characters before or after
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the period are generally ignored by MS-DOS itself; thus, if you visit
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the file @file{LongFileName.EvenLongerExtension}, you will silently
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get @file{longfile.eve}, but Emacs will still display the long file
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name on the mode line. Other than that, it's up to you to specify
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file names which are valid under MS-DOS; the transparent conversion as
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described above only works on file names built into Emacs.
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@cindex backup file names on MS-DOS
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The above restrictions on the file names on MS-DOS make it almost
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impossible to construct the name of a backup file
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@iftex
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(@pxref{Backup Names,,,emacs, the Emacs Manual})
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@end iftex
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@ifnottex
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(@pxref{Backup Names})
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@end ifnottex
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without losing some of the original file name characters. For
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example, the name of a backup file for @file{docs.txt} is
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@file{docs.tx~} even if single backup is used.
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@cindex file names under Windows 95/NT
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@cindex long file names in DOS box under Windows 95/NT
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If you run Emacs as a DOS application under Windows 9X, Windows ME, or
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Windows 2000/XP, you can turn on support for long file names. If you do
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that, Emacs doesn't truncate file names or convert them to lower case;
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instead, it uses the file names that you specify, verbatim. To enable
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long file name support, set the environment variable @env{LFN} to
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@samp{y} before starting Emacs. Unfortunately, Windows NT doesn't allow
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DOS programs to access long file names, so Emacs built for MS-DOS will
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only see their short 8+3 aliases.
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@cindex @env{HOME} directory under MS-DOS
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MS-DOS has no notion of home directory, so Emacs on MS-DOS pretends
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that the directory where it is installed is the value of the @env{HOME}
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environment variable. That is, if your Emacs binary,
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@file{emacs.exe}, is in the directory @file{c:/utils/emacs/bin}, then
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Emacs acts as if @env{HOME} were set to @samp{c:/utils/emacs}. In
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particular, that is where Emacs looks for the init file @file{_emacs}.
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With this in mind, you can use @samp{~} in file names as an alias for
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the home directory, as you would on GNU or Unix. You can also set
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@env{HOME} variable in the environment before starting Emacs; its
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value will then override the above default behavior.
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Emacs on MS-DOS handles the directory name @file{/dev} specially,
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because of a feature in the emulator libraries of DJGPP that pretends
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I/O devices have names in that directory. We recommend that you avoid
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using an actual directory named @file{/dev} on any disk.
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@node MS-DOS Printing
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@subsection Printing and MS-DOS
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Printing commands, such as @code{lpr-buffer}
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@iftex
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(@pxref{Printing,,,emacs, the Emacs Manual}) and @code{ps-print-buffer}
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(@pxref{PostScript,,,emacs, the Emacs Manual})
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@end iftex
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@ifnottex
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(@pxref{Printing}) and @code{ps-print-buffer} (@pxref{PostScript})
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@end ifnottex
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can work on MS-DOS by sending the output to one of the printer ports,
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if a Posix-style @code{lpr} program is unavailable. The same Emacs
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variables control printing on all systems, but in some cases they have
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different default values on MS-DOS.
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@iftex
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@xref{Windows Printing,,,emacs, the Emacs Manual},
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@end iftex
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@ifnottex
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@xref{Windows Printing},
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@end ifnottex
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for details about setting up printing to a networked printer.
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Some printers expect DOS codepage encoding of non-@acronym{ASCII} text, even
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though they are connected to a Windows machine which uses a different
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encoding for the same locale. For example, in the Latin-1 locale, DOS
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uses codepage 850 whereas Windows uses codepage 1252. @xref{MS-DOS and
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MULE}. When you print to such printers from Windows, you can use the
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@kbd{C-x RET c} (@code{universal-coding-system-argument}) command before
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@kbd{M-x lpr-buffer}; Emacs will then convert the text to the DOS
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codepage that you specify. For example, @kbd{C-x RET c cp850-dos RET
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M-x lpr-region RET} will print the region while converting it to the
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codepage 850 encoding. You may need to create the @code{cp@var{nnn}}
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coding system with @kbd{M-x codepage-setup}.
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@vindex dos-printer
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@vindex dos-ps-printer
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For backwards compatibility, the value of @code{dos-printer}
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(@code{dos-ps-printer}), if it has a value, overrides the value of
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@code{printer-name} (@code{ps-printer-name}), on MS-DOS.
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@node MS-DOS and MULE
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@subsection International Support on MS-DOS
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@cindex international support @r{(MS-DOS)}
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Emacs on MS-DOS supports the same international character sets as it
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does on GNU, Unix and other platforms
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@iftex
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(@pxref{International,,,emacs, the Emacs Manual}),
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@end iftex
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@ifnottex
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(@pxref{International}),
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|
@end ifnottex
|
|
including coding systems for converting between the different
|
|
character sets. However, due to incompatibilities between
|
|
MS-DOS/MS-Windows and other systems, there are several DOS-specific
|
|
aspects of this support that you should be aware of. This section
|
|
describes these aspects.
|
|
|
|
The description below is largely specific to the MS-DOS port of
|
|
Emacs, especially where it talks about practical implications for
|
|
Emacs users. For other operating systems, see the @file{code-pages.el}
|
|
package, which implements support for MS-DOS- and MS-Windows-specific
|
|
encodings for all platforms other than MS-DOS.
|
|
|
|
@table @kbd
|
|
@item M-x dos-codepage-setup
|
|
Set up Emacs display and coding systems as appropriate for the current
|
|
DOS codepage.
|
|
|
|
@item M-x codepage-setup
|
|
Create a coding system for a certain DOS codepage.
|
|
@end table
|
|
|
|
@cindex codepage, MS-DOS
|
|
@cindex DOS codepages
|
|
MS-DOS is designed to support one character set of 256 characters at
|
|
any given time, but gives you a variety of character sets to choose
|
|
from. The alternative character sets are known as @dfn{DOS codepages}.
|
|
Each codepage includes all 128 @acronym{ASCII} characters, but the other 128
|
|
characters (codes 128 through 255) vary from one codepage to another.
|
|
Each DOS codepage is identified by a 3-digit number, such as 850, 862,
|
|
etc.
|
|
|
|
In contrast to X, which lets you use several fonts at the same time,
|
|
MS-DOS normally doesn't allow use of several codepages in a single
|
|
session. MS-DOS was designed to load a single codepage at system
|
|
startup, and require you to reboot in order to change
|
|
it@footnote{Normally, one particular codepage is burnt into the
|
|
display memory, while other codepages can be installed by modifying
|
|
system configuration files, such as @file{CONFIG.SYS}, and rebooting.
|
|
While there is third-party software that allows changing the codepage
|
|
without rebooting, we describe here how a stock MS-DOS system
|
|
behaves.}. Much the same limitation applies when you run DOS
|
|
executables on other systems such as MS-Windows.
|
|
|
|
@cindex unibyte operation @r{(MS-DOS)}
|
|
If you invoke Emacs on MS-DOS with the @samp{--unibyte} option
|
|
@iftex
|
|
(@pxref{Initial Options,,,emacs, the Emacs Manual}),
|
|
@end iftex
|
|
@ifnottex
|
|
(@pxref{Initial Options}),
|
|
@end ifnottex
|
|
Emacs does not perform any conversion of non-@acronym{ASCII}
|
|
characters. Instead, it reads and writes any non-@acronym{ASCII}
|
|
characters verbatim, and sends their 8-bit codes to the display
|
|
verbatim. Thus, unibyte Emacs on MS-DOS supports the current
|
|
codepage, whatever it may be, but cannot even represent any other
|
|
characters.
|
|
|
|
@vindex dos-codepage
|
|
For multibyte operation on MS-DOS, Emacs needs to know which
|
|
characters the chosen DOS codepage can display. So it queries the
|
|
system shortly after startup to get the chosen codepage number, and
|
|
stores the number in the variable @code{dos-codepage}. Some systems
|
|
return the default value 437 for the current codepage, even though the
|
|
actual codepage is different. (This typically happens when you use the
|
|
codepage built into the display hardware.) You can specify a different
|
|
codepage for Emacs to use by setting the variable @code{dos-codepage} in
|
|
your init file.
|
|
|
|
@cindex language environment, automatic selection on @r{MS-DOS}
|
|
Multibyte Emacs supports only certain DOS codepages: those which can
|
|
display Far-Eastern scripts, like the Japanese codepage 932, and those
|
|
that encode a single ISO 8859 character set.
|
|
|
|
The Far-Eastern codepages can directly display one of the MULE
|
|
character sets for these countries, so Emacs simply sets up to use the
|
|
appropriate terminal coding system that is supported by the codepage.
|
|
The special features described in the rest of this section mostly
|
|
pertain to codepages that encode ISO 8859 character sets.
|
|
|
|
For the codepages which correspond to one of the ISO character sets,
|
|
Emacs knows the character set name based on the codepage number. Emacs
|
|
automatically creates a coding system to support reading and writing
|
|
files that use the current codepage, and uses this coding system by
|
|
default. The name of this coding system is @code{cp@var{nnn}}, where
|
|
@var{nnn} is the codepage number.@footnote{The standard Emacs coding
|
|
systems for ISO 8859 are not quite right for the purpose, because
|
|
typically the DOS codepage does not match the standard ISO character
|
|
codes. For example, the letter @samp{@,{c}} (@samp{c} with cedilla) has
|
|
code 231 in the standard Latin-1 character set, but the corresponding
|
|
DOS codepage 850 uses code 135 for this glyph.}
|
|
|
|
@cindex mode line @r{(MS-DOS)}
|
|
All the @code{cp@var{nnn}} coding systems use the letter @samp{D}
|
|
(for ``DOS'') as their mode-line mnemonic. Since both the terminal
|
|
coding system and the default coding system for file I/O are set to
|
|
the proper @code{cp@var{nnn}} coding system at startup, it is normal
|
|
for the mode line on MS-DOS to begin with @samp{-DD\-}.
|
|
@iftex
|
|
@xref{Mode Line,,,emacs, the Emacs Manual}.
|
|
@end iftex
|
|
@ifnottex
|
|
@xref{Mode Line}.
|
|
@end ifnottex
|
|
Far-Eastern DOS terminals do not use the @code{cp@var{nnn}} coding
|
|
systems, and thus their initial mode line looks like the Emacs
|
|
default.
|
|
|
|
Since the codepage number also indicates which script you are using,
|
|
Emacs automatically runs @code{set-language-environment} to select the
|
|
language environment for that script
|
|
@iftex
|
|
(@pxref{Language Environments,,,emacs, the Emacs Manual}).
|
|
@end iftex
|
|
@ifnottex
|
|
(@pxref{Language Environments}).
|
|
@end ifnottex
|
|
|
|
If a buffer contains a character belonging to some other ISO 8859
|
|
character set, not the one that the chosen DOS codepage supports, Emacs
|
|
displays it using a sequence of @acronym{ASCII} characters. For example, if the
|
|
current codepage doesn't have a glyph for the letter @samp{@`o} (small
|
|
@samp{o} with a grave accent), it is displayed as @samp{@{`o@}}, where
|
|
the braces serve as a visual indication that this is a single character.
|
|
(This may look awkward for some non-Latin characters, such as those from
|
|
Greek or Hebrew alphabets, but it is still readable by a person who
|
|
knows the language.) Even though the character may occupy several
|
|
columns on the screen, it is really still just a single character, and
|
|
all Emacs commands treat it as one.
|
|
|
|
@cindex IBM graphics characters (MS-DOS)
|
|
@cindex box-drawing characters (MS-DOS)
|
|
@cindex line-drawing characters (MS-DOS)
|
|
Not all characters in DOS codepages correspond to ISO 8859
|
|
characters---some are used for other purposes, such as box-drawing
|
|
characters and other graphics. Emacs maps these characters to two
|
|
special character sets called @code{eight-bit-control} and
|
|
@code{eight-bit-graphic}, and displays them as their IBM glyphs.
|
|
However, you should be aware that other systems might display these
|
|
characters differently, so you should avoid them in text that might be
|
|
copied to a different operating system, or even to another DOS machine
|
|
that uses a different codepage.
|
|
|
|
@vindex dos-unsupported-character-glyph
|
|
Emacs supports many other characters sets aside from ISO 8859, but it
|
|
cannot display them on MS-DOS. So if one of these multibyte characters
|
|
appears in a buffer, Emacs on MS-DOS displays them as specified by the
|
|
@code{dos-unsupported-character-glyph} variable; by default, this glyph
|
|
is an empty triangle. Use the @kbd{C-u C-x =} command to display the
|
|
actual code and character set of such characters.
|
|
@iftex
|
|
@xref{Position Info,,,emacs, the Emacs Manual}.
|
|
@end iftex
|
|
@ifnottex
|
|
@xref{Position Info}.
|
|
@end ifnottex
|
|
|
|
@findex codepage-setup
|
|
By default, Emacs defines a coding system to support the current
|
|
codepage. To define a coding system for some other codepage (e.g., to
|
|
visit a file written on a DOS machine in another country), use the
|
|
@kbd{M-x codepage-setup} command. It prompts for the 3-digit code of
|
|
the codepage, with completion, then creates the coding system for the
|
|
specified codepage. You can then use the new coding system to read and
|
|
write files, but you must specify it explicitly for the file command
|
|
when you want to use it
|
|
@iftex
|
|
(@pxref{Text Coding,,,emacs, the Emacs Manual}).
|
|
@end iftex
|
|
@ifnottex
|
|
(@pxref{Text Coding}).
|
|
@end ifnottex
|
|
|
|
These coding systems are also useful for visiting a file encoded using
|
|
a DOS codepage, using Emacs running on some other operating system.
|
|
|
|
@cindex MS-Windows codepages
|
|
MS-Windows provides its own codepages, which are different from the
|
|
DOS codepages for the same locale. For example, DOS codepage 850
|
|
supports the same character set as Windows codepage 1252; DOS codepage
|
|
855 supports the same character set as Windows codepage 1251, etc.
|
|
The MS-Windows version of Emacs uses the current codepage for display
|
|
when invoked with the @samp{-nw} option. Support for codepages in the
|
|
Windows port of Emacs is part of the @file{code-pages.el} package.
|
|
|
|
@node MS-DOS Processes
|
|
@subsection Subprocesses on MS-DOS
|
|
|
|
@cindex compilation under MS-DOS
|
|
@cindex inferior processes under MS-DOS
|
|
@findex compile @r{(MS-DOS)}
|
|
@findex grep @r{(MS-DOS)}
|
|
Because MS-DOS is a single-process ``operating system,''
|
|
asynchronous subprocesses are not available. In particular, Shell
|
|
mode and its variants do not work. Most Emacs features that use
|
|
asynchronous subprocesses also don't work on MS-DOS, including
|
|
Shell mode and GUD. When in doubt, try and see; commands that
|
|
don't work output an error message saying that asynchronous processes
|
|
aren't supported.
|
|
|
|
Compilation under Emacs with @kbd{M-x compile}, searching files with
|
|
@kbd{M-x grep} and displaying differences between files with @kbd{M-x
|
|
diff} do work, by running the inferior processes synchronously. This
|
|
means you cannot do any more editing until the inferior process
|
|
finishes.
|
|
|
|
Spell checking also works, by means of special support for synchronous
|
|
invocation of the @code{ispell} program. This is slower than the
|
|
asynchronous invocation on other platforms
|
|
|
|
Instead of the Shell mode, which doesn't work on MS-DOS, you can use
|
|
the @kbd{M-x eshell} command. This invokes the Eshell package that
|
|
implements a Posix-like shell entirely in Emacs Lisp.
|
|
|
|
By contrast, Emacs compiled as a native Windows application
|
|
@strong{does} support asynchronous subprocesses.
|
|
@iftex
|
|
@xref{Windows Processes,,,emacs, the Emacs Manual}.
|
|
@end iftex
|
|
@ifnottex
|
|
@xref{Windows Processes}.
|
|
@end ifnottex
|
|
|
|
@cindex printing under MS-DOS
|
|
Printing commands, such as @code{lpr-buffer}
|
|
@iftex
|
|
(@pxref{Printing,,,emacs, the Emacs Manual}) and
|
|
@code{ps-print-buffer} (@pxref{PostScript,,,emacs, the Emacs Manual}),
|
|
work in MS-DOS by sending the output to one of the printer ports.
|
|
@xref{MS-DOS Printing,,,emacs, the Emacs Manual}.
|
|
@end iftex
|
|
@ifnottex
|
|
(@pxref{Printing}) and @code{ps-print-buffer} (@pxref{PostScript}),
|
|
work in MS-DOS by sending the output to one of the printer ports.
|
|
@xref{MS-DOS Printing}.
|
|
@end ifnottex
|
|
|
|
When you run a subprocess synchronously on MS-DOS, make sure the
|
|
program terminates and does not try to read keyboard input. If the
|
|
program does not terminate on its own, you will be unable to terminate
|
|
it, because MS-DOS provides no general way to terminate a process.
|
|
Pressing @kbd{C-c} or @kbd{C-@key{BREAK}} might sometimes help in these
|
|
cases.
|
|
|
|
Accessing files on other machines is not supported on MS-DOS. Other
|
|
network-oriented commands such as sending mail, Web browsing, remote
|
|
login, etc., don't work either, unless network access is built into
|
|
MS-DOS with some network redirector.
|
|
|
|
@cindex directory listing on MS-DOS
|
|
@vindex dired-listing-switches @r{(MS-DOS)}
|
|
Dired on MS-DOS uses the @code{ls-lisp} package where other
|
|
platforms use the system @code{ls} command. Therefore, Dired on
|
|
MS-DOS supports only some of the possible options you can mention in
|
|
the @code{dired-listing-switches} variable. The options that work are
|
|
@samp{-A}, @samp{-a}, @samp{-c}, @samp{-i}, @samp{-r}, @samp{-S},
|
|
@samp{-s}, @samp{-t}, and @samp{-u}.
|
|
|
|
@ignore
|
|
arch-tag: 868d50ff-07f8-4a13-a807-dab6f1cdb431
|
|
@end ignore
|