| 1 | @c This is part of the Emacs manual. |
| 2 | @c Copyright (C) 1985,86,87,93,94,95,1997,2000,2001 |
| 3 | @c Free Software Foundation, Inc. |
| 4 | @c See file emacs.texi for copying conditions. |
| 5 | @node MS-DOS, Manifesto, Mac OS, Top |
| 6 | @appendix Emacs and MS-DOS |
| 7 | @cindex MS-DOG |
| 8 | @cindex MS-DOS peculiarities |
| 9 | |
| 10 | This section briefly describes the peculiarities of using Emacs under |
| 11 | the MS-DOS ``operating system'' (also known as ``MS-DOG''). If you |
| 12 | build Emacs for MS-DOS, the binary will also run on Windows 3.X, Windows |
| 13 | NT, Windows 9X/ME, Windows 2000, or OS/2 as a DOS application; the |
| 14 | information in this chapter applies for all of those systems, if you use |
| 15 | an Emacs that was built for MS-DOS. |
| 16 | |
| 17 | Note that it is possible to build Emacs specifically for Windows NT/2K |
| 18 | or Windows 9X/ME. If you do that, most of this chapter does not apply; |
| 19 | instead, you get behavior much closer to what is documented in the rest |
| 20 | of the manual, including support for long file names, multiple frames, |
| 21 | scroll bars, mouse menus, and subprocesses. However, the section on |
| 22 | text files and binary files does still apply. There are also two |
| 23 | sections at the end of this chapter which apply specifically for the |
| 24 | Windows version. |
| 25 | |
| 26 | @menu |
| 27 | * Input: MS-DOS Input. Keyboard and mouse usage on MS-DOS. |
| 28 | * Display: MS-DOS Display. Fonts, frames and display size on MS-DOS. |
| 29 | * Files: MS-DOS File Names. File name conventions on MS-DOS. |
| 30 | * Text and Binary:: Text files on MS-DOS use CRLF to separate lines. |
| 31 | * Printing: MS-DOS Printing. How to specify the printer on MS-DOS. |
| 32 | * I18N: MS-DOS and MULE. Support for internationalization on MS-DOS. |
| 33 | * Processes: MS-DOS Processes. Running subprocesses on MS-DOS. |
| 34 | * Windows Processes:: Running subprocesses on Windows. |
| 35 | * Windows System Menu:: Controlling what the ALT key does. |
| 36 | @end menu |
| 37 | |
| 38 | @node MS-DOS Input |
| 39 | @section Keyboard and Mouse on MS-DOS |
| 40 | |
| 41 | @cindex Meta (under MS-DOS) |
| 42 | @cindex Hyper (under MS-DOS) |
| 43 | @cindex Super (under MS-DOS) |
| 44 | @vindex dos-super-key |
| 45 | @vindex dos-hyper-key |
| 46 | The PC keyboard maps use the left @key{ALT} key as the @key{META} key. |
| 47 | You have two choices for emulating the @key{SUPER} and @key{HYPER} keys: |
| 48 | choose either the right @key{CTRL} key or the right @key{ALT} key by |
| 49 | setting the variables @code{dos-hyper-key} and @code{dos-super-key} to 1 |
| 50 | or 2 respectively. If neither @code{dos-super-key} nor |
| 51 | @code{dos-hyper-key} is 1, then by default the right @key{ALT} key is |
| 52 | also mapped to the @key{META} key. However, if the MS-DOS international |
| 53 | keyboard support program @file{KEYB.COM} is installed, Emacs will |
| 54 | @emph{not} map the right @key{ALT} to @key{META}, since it is used for |
| 55 | accessing characters like @kbd{~} and @kbd{@@} on non-US keyboard |
| 56 | layouts; in this case, you may only use the left @key{ALT} as @key{META} |
| 57 | key. |
| 58 | |
| 59 | @kindex C-j @r{(MS-DOS)} |
| 60 | @vindex dos-keypad-mode |
| 61 | The variable @code{dos-keypad-mode} is a flag variable that controls |
| 62 | what key codes are returned by keys in the numeric keypad. You can also |
| 63 | define the keypad @key{ENTER} key to act like @kbd{C-j}, by putting the |
| 64 | following line into your @file{_emacs} file: |
| 65 | |
| 66 | @smallexample |
| 67 | ;; @r{Make the @key{ENTER} key from the numeric keypad act as @kbd{C-j}.} |
| 68 | (define-key function-key-map [kp-enter] [?\C-j]) |
| 69 | @end smallexample |
| 70 | |
| 71 | @kindex DEL @r{(MS-DOS)} |
| 72 | @kindex BS @r{(MS-DOS)} |
| 73 | The key that is called @key{DEL} in Emacs (because that's how it is |
| 74 | designated on most workstations) is known as @key{BS} (backspace) on a |
| 75 | PC. That is why the PC-specific terminal initialization remaps the |
| 76 | @key{BS} key to act as @key{DEL}; the @key{DEL} key is remapped to act |
| 77 | as @kbd{C-d} for the same reasons. |
| 78 | |
| 79 | @kindex C-g @r{(MS-DOS)} |
| 80 | @kindex C-BREAK @r{(MS-DOS)} |
| 81 | @cindex quitting on MS-DOS |
| 82 | Emacs built for MS-DOS recognizes @kbd{C-@key{BREAK}} as a quit |
| 83 | character, just like @kbd{C-g}. This is because Emacs cannot detect |
| 84 | that you have typed @kbd{C-g} until it is ready for more input. As a |
| 85 | consequence, you cannot use @kbd{C-g} to stop a running command |
| 86 | (@pxref{Quitting}). By contrast, @kbd{C-@key{BREAK}} @emph{is} detected |
| 87 | as soon as you type it (as @kbd{C-g} is on other systems), so it can be |
| 88 | used to stop a running command and for emergency escape |
| 89 | (@pxref{Emergency Escape}). |
| 90 | |
| 91 | @cindex mouse support under MS-DOS |
| 92 | Emacs on MS-DOS supports a mouse (on the default terminal only). |
| 93 | The mouse commands work as documented, including those that use menus |
| 94 | and the menu bar (@pxref{Menu Bar}). Scroll bars don't work in |
| 95 | MS-DOS Emacs. PC mice usually have only two buttons; these act as |
| 96 | @kbd{Mouse-1} and @kbd{Mouse-2}, but if you press both of them |
| 97 | together, that has the effect of @kbd{Mouse-3}. If the mouse does have |
| 98 | 3 buttons, Emacs detects that at startup, and all the 3 buttons function |
| 99 | normally, as on X. |
| 100 | |
| 101 | Help strings for menu-bar and pop-up menus are displayed in the echo |
| 102 | area when the mouse pointer moves across the menu items. |
| 103 | Highlighting of mouse-sensitive text (@pxref{Mouse References}) is also |
| 104 | supported. |
| 105 | |
| 106 | @cindex mouse, set number of buttons |
| 107 | @findex msdos-set-mouse-buttons |
| 108 | Some versions of mouse drivers don't report the number of mouse |
| 109 | buttons correctly. For example, mice with a wheel report that they |
| 110 | have 3 buttons, but only 2 of them are passed to Emacs; the clicks on |
| 111 | the wheel, which serves as the middle button, are not passed. In |
| 112 | these cases, you can use the @kbd{M-x msdos-set-mouse-buttons} command |
| 113 | to tell Emacs how many mouse buttons to expect. You could make such a |
| 114 | setting permanent by adding this fragment to your @file{_emacs} init |
| 115 | file: |
| 116 | |
| 117 | @example |
| 118 | ;; @r{Treat the mouse like a 2-button mouse.} |
| 119 | (msdos-set-mouse-buttons 2) |
| 120 | @end example |
| 121 | |
| 122 | @cindex Windows clipboard support |
| 123 | Emacs built for MS-DOS supports clipboard operations when it runs on |
| 124 | Windows. Commands that put text on the kill ring, or yank text from the |
| 125 | ring, check the Windows clipboard first, just as Emacs does on the X |
| 126 | Window System (@pxref{Mouse Commands}). Only the primary selection and |
| 127 | the cut buffer are supported by MS-DOS Emacs on Windows; the secondary |
| 128 | selection always appears as empty. |
| 129 | |
| 130 | Due to the way clipboard access is implemented by Windows, the |
| 131 | length of text you can put into the clipboard is limited by the amount |
| 132 | of free DOS memory that is available to Emacs. Usually, up to 620KB of |
| 133 | text can be put into the clipboard, but this limit depends on the system |
| 134 | configuration and is lower if you run Emacs as a subprocess of |
| 135 | another program. If the killed text does not fit, Emacs outputs a |
| 136 | message saying so, and does not put the text into the clipboard. |
| 137 | |
| 138 | Null characters also cannot be put into the Windows clipboard. If the |
| 139 | killed text includes null characters, Emacs does not put such text into |
| 140 | the clipboard, and displays in the echo area a message to that effect. |
| 141 | |
| 142 | @vindex dos-display-scancodes |
| 143 | The variable @code{dos-display-scancodes}, when non-@code{nil}, |
| 144 | directs Emacs to display the ASCII value and the keyboard scan code of |
| 145 | each keystroke; this feature serves as a complement to the |
| 146 | @code{view-lossage} command, for debugging. |
| 147 | |
| 148 | @node MS-DOS Display |
| 149 | @section Display on MS-DOS |
| 150 | @cindex faces under MS-DOS |
| 151 | @cindex fonts, emulating under MS-DOS |
| 152 | |
| 153 | Display on MS-DOS cannot use font variants, like bold or italic, |
| 154 | but it does support |
| 155 | multiple faces, each of which can specify a foreground and a background |
| 156 | color. Therefore, you can get the full functionality of Emacs packages |
| 157 | that use fonts (such as @code{font-lock}, Enriched Text mode, and |
| 158 | others) by defining the relevant faces to use different colors. Use the |
| 159 | @code{list-colors-display} command (@pxref{Frame Parameters}) and the |
| 160 | @code{list-faces-display} command (@pxref{Faces}) to see what colors and |
| 161 | faces are available and what they look like. |
| 162 | |
| 163 | @xref{MS-DOS and MULE}, later in this chapter, for information on |
| 164 | how Emacs displays glyphs and characters that aren't supported by the |
| 165 | native font built into the DOS display. |
| 166 | |
| 167 | @cindex cursor shape on MS-DOS |
| 168 | When Emacs starts, it changes the cursor shape to a solid box. This |
| 169 | is for compatibility with other systems, where the box cursor is the |
| 170 | default in Emacs. This default shape can be changed to a bar by |
| 171 | specifying the @code{cursor-type} parameter in the variable |
| 172 | @code{default-frame-alist} (@pxref{Creating Frames}). The MS-DOS |
| 173 | terminal doesn't support a vertical-bar cursor, so the bar cursor is |
| 174 | horizontal, and the @code{@var{width}} parameter, if specified by the |
| 175 | frame parameters, actually determines its height. As an extension, |
| 176 | the bar cursor specification can include the starting scan line of the |
| 177 | cursor as well as its width, like this: |
| 178 | |
| 179 | @example |
| 180 | '(cursor-type bar @var{width} . @var{start}) |
| 181 | @end example |
| 182 | |
| 183 | @noindent |
| 184 | In addition, if the @var{width} parameter is negative, the cursor bar |
| 185 | begins at the top of the character cell. |
| 186 | |
| 187 | @cindex frames on MS-DOS |
| 188 | The MS-DOS terminal can only display a single frame at a time. The |
| 189 | Emacs frame facilities work on MS-DOS much as they do on text-only |
| 190 | terminals (@pxref{Frames}). When you run Emacs from a DOS window on |
| 191 | MS-Windows, you can make the visible frame smaller than the full |
| 192 | screen, but Emacs still cannot display more than a single frame at a |
| 193 | time. |
| 194 | |
| 195 | @cindex frame size under MS-DOS |
| 196 | @findex mode4350 |
| 197 | @findex mode25 |
| 198 | The @code{mode4350} command switches the display to 43 or 50 |
| 199 | lines, depending on your hardware; the @code{mode25} command switches |
| 200 | to the default 80x25 screen size. |
| 201 | |
| 202 | By default, Emacs only knows how to set screen sizes of 80 columns by |
| 203 | 25, 28, 35, 40, 43 or 50 rows. However, if your video adapter has |
| 204 | special video modes that will switch the display to other sizes, you can |
| 205 | have Emacs support those too. When you ask Emacs to switch the frame to |
| 206 | @var{n} rows by @var{m} columns dimensions, it checks if there is a |
| 207 | variable called @code{screen-dimensions-@var{n}x@var{m}}, and if so, |
| 208 | uses its value (which must be an integer) as the video mode to switch |
| 209 | to. (Emacs switches to that video mode by calling the BIOS @code{Set |
| 210 | Video Mode} function with the value of |
| 211 | @code{screen-dimensions-@var{n}x@var{m}} in the @code{AL} register.) |
| 212 | For example, suppose your adapter will switch to 66x80 dimensions when |
| 213 | put into video mode 85. Then you can make Emacs support this screen |
| 214 | size by putting the following into your @file{_emacs} file: |
| 215 | |
| 216 | @example |
| 217 | (setq screen-dimensions-66x80 85) |
| 218 | @end example |
| 219 | |
| 220 | Since Emacs on MS-DOS can only set the frame size to specific |
| 221 | supported dimensions, it cannot honor every possible frame resizing |
| 222 | request. When an unsupported size is requested, Emacs chooses the next |
| 223 | larger supported size beyond the specified size. For example, if you |
| 224 | ask for 36x80 frame, you will get 40x80 instead. |
| 225 | |
| 226 | The variables @code{screen-dimensions-@var{n}x@var{m}} are used only |
| 227 | when they exactly match the specified size; the search for the next |
| 228 | larger supported size ignores them. In the above example, even if your |
| 229 | VGA supports 38x80 dimensions and you define a variable |
| 230 | @code{screen-dimensions-38x80} with a suitable value, you will still get |
| 231 | 40x80 screen when you ask for a 36x80 frame. If you want to get the |
| 232 | 38x80 size in this case, you can do it by setting the variable named |
| 233 | @code{screen-dimensions-36x80} with the same video mode value as |
| 234 | @code{screen-dimensions-38x80}. |
| 235 | |
| 236 | Changing frame dimensions on MS-DOS has the effect of changing all the |
| 237 | other frames to the new dimensions. |
| 238 | |
| 239 | @node MS-DOS File Names |
| 240 | @section File Names on MS-DOS |
| 241 | @cindex file names under MS-DOS |
| 242 | @cindex init file, default name under MS-DOS |
| 243 | |
| 244 | MS-DOS normally uses a backslash, @samp{\}, to separate name units |
| 245 | within a file name, instead of the slash used on other systems. Emacs |
| 246 | on MS-DOS permits use of either slash or backslash, and also knows |
| 247 | about drive letters in file names. |
| 248 | |
| 249 | On MS-DOS, file names are case-insensitive and limited to eight |
| 250 | characters, plus optionally a period and three more characters. Emacs |
| 251 | knows enough about these limitations to handle file names that were |
| 252 | meant for other operating systems. For instance, leading dots @samp{.} |
| 253 | in file names are invalid in MS-DOS, so Emacs transparently converts |
| 254 | them to underscores @samp{_}; thus your default init file (@pxref{Init |
| 255 | File}) is called @file{_emacs} on MS-DOS. Excess characters before or |
| 256 | after the period are generally ignored by MS-DOS itself; thus, if you |
| 257 | visit the file @file{LongFileName.EvenLongerExtension}, you will |
| 258 | silently get @file{longfile.eve}, but Emacs will still display the long |
| 259 | file name on the mode line. Other than that, it's up to you to specify |
| 260 | file names which are valid under MS-DOS; the transparent conversion as |
| 261 | described above only works on file names built into Emacs. |
| 262 | |
| 263 | @cindex backup file names on MS-DOS |
| 264 | The above restrictions on the file names on MS-DOS make it almost |
| 265 | impossible to construct the name of a backup file (@pxref{Backup |
| 266 | Names}) without losing some of the original file name characters. For |
| 267 | example, the name of a backup file for @file{docs.txt} is |
| 268 | @file{docs.tx~} even if single backup is used. |
| 269 | |
| 270 | @cindex file names under Windows 95/NT |
| 271 | @cindex long file names in DOS box under Windows 95/NT |
| 272 | If you run Emacs as a DOS application under Windows 9X, Windows ME, or |
| 273 | Windows 2000, you can turn on support for long file names. If you do |
| 274 | that, Emacs doesn't truncate file names or convert them to lower case; |
| 275 | instead, it uses the file names that you specify, verbatim. To enable |
| 276 | long file name support, set the environment variable @env{LFN} to |
| 277 | @samp{y} before starting Emacs. Unfortunately, Windows NT doesn't allow |
| 278 | DOS programs to access long file names, so Emacs built for MS-DOS will |
| 279 | only see their short 8+3 aliases. |
| 280 | |
| 281 | @cindex @env{HOME} directory under MS-DOS |
| 282 | MS-DOS has no notion of home directory, so Emacs on MS-DOS pretends |
| 283 | that the directory where it is installed is the value of @env{HOME} |
| 284 | environment variable. That is, if your Emacs binary, |
| 285 | @file{emacs.exe}, is in the directory @file{c:/utils/emacs/bin}, then |
| 286 | Emacs acts as if @env{HOME} were set to @samp{c:/utils/emacs}. In |
| 287 | particular, that is where Emacs looks for the init file @file{_emacs}. |
| 288 | With this in mind, you can use @samp{~} in file names as an alias for |
| 289 | the home directory, as you would on GNU or Unix. You can also set |
| 290 | @env{HOME} variable in the environment before starting Emacs; its |
| 291 | value will then override the above default behavior. |
| 292 | |
| 293 | Emacs on MS-DOS handles the directory name @file{/dev} specially, |
| 294 | because of a feature in the emulator libraries of DJGPP that pretends |
| 295 | I/O devices have names in that directory. We recommend that you avoid |
| 296 | using an actual directory named @file{/dev} on any disk. |
| 297 | |
| 298 | @node Text and Binary |
| 299 | @section Text Files and Binary Files |
| 300 | @cindex text and binary files on MS-DOS/MS-Windows |
| 301 | |
| 302 | GNU Emacs uses newline characters to separate text lines. This is the |
| 303 | convention used on GNU and Unix. |
| 304 | |
| 305 | @cindex end-of-line conversion on MS-DOS/MS-Windows |
| 306 | MS-DOS and MS-Windows normally use carriage-return linefeed, a |
| 307 | two-character sequence, to separate text lines. (Linefeed is the same |
| 308 | character as newline.) Therefore, convenient editing of typical files |
| 309 | with Emacs requires conversion of these end-of-line (EOL) sequences. |
| 310 | And that is what Emacs normally does: it converts carriage-return |
| 311 | linefeed into newline when reading files, and converts newline into |
| 312 | carriage-return linefeed when writing files. The same mechanism that |
| 313 | handles conversion of international character codes does this conversion |
| 314 | also (@pxref{Coding Systems}). |
| 315 | |
| 316 | @cindex cursor location, on MS-DOS |
| 317 | @cindex point location, on MS-DOS |
| 318 | One consequence of this special format-conversion of most files is |
| 319 | that character positions as reported by Emacs (@pxref{Position Info}) do |
| 320 | not agree with the file size information known to the operating system. |
| 321 | |
| 322 | In addition, if Emacs recognizes from a file's contents that it uses |
| 323 | newline rather than carriage-return linefeed as its line separator, it |
| 324 | does not perform EOL conversion when reading or writing that file. |
| 325 | Thus, you can read and edit files from GNU and Unix systems on MS-DOS |
| 326 | with no special effort, and they will retain their Unix-style |
| 327 | end-of-line convention after you edit them. |
| 328 | |
| 329 | The mode line indicates whether end-of-line translation was used for |
| 330 | the current buffer. If MS-DOS end-of-line translation is in use for the |
| 331 | buffer, a backslash @samp{\} is displayed after the coding system |
| 332 | mnemonic near the beginning of the mode line (@pxref{Mode Line}). If no |
| 333 | EOL translation was performed, the string @samp{(Unix)} is displayed |
| 334 | instead of the backslash, to alert you that the file's EOL format is not |
| 335 | the usual carriage-return linefeed. |
| 336 | |
| 337 | @cindex DOS-to-Unix conversion of files |
| 338 | To visit a file and specify whether it uses DOS-style or Unix-style |
| 339 | end-of-line, specify a coding system (@pxref{Specify Coding}). For |
| 340 | example, @kbd{C-x @key{RET} c unix @key{RET} C-x C-f foobar.txt} |
| 341 | visits the file @file{foobar.txt} without converting the EOLs; if some |
| 342 | line ends with a carriage-return linefeed pair, Emacs will display |
| 343 | @samp{^M} at the end of that line. Similarly, you can direct Emacs to |
| 344 | save a buffer in a specified EOL format with the @kbd{C-x @key{RET} f} |
| 345 | command. For example, to save a buffer with Unix EOL format, type |
| 346 | @kbd{C-x @key{RET} f unix @key{RET} C-x C-s}. If you visit a file |
| 347 | with DOS EOL conversion, then save it with Unix EOL format, that |
| 348 | effectively converts the file to Unix EOL style, like @code{dos2unix}. |
| 349 | |
| 350 | @cindex untranslated file system |
| 351 | @findex add-untranslated-filesystem |
| 352 | When you use NFS or Samba to access file systems that reside on |
| 353 | computers using GNU or Unix systems, Emacs should not perform |
| 354 | end-of-line translation on any files in these file systems--not even |
| 355 | when you create a new file. To request this, designate these file |
| 356 | systems as @dfn{untranslated} file systems by calling the function |
| 357 | @code{add-untranslated-filesystem}. It takes one argument: the file |
| 358 | system name, including a drive letter and optionally a directory. For |
| 359 | example, |
| 360 | |
| 361 | @example |
| 362 | (add-untranslated-filesystem "Z:") |
| 363 | @end example |
| 364 | |
| 365 | @noindent |
| 366 | designates drive Z as an untranslated file system, and |
| 367 | |
| 368 | @example |
| 369 | (add-untranslated-filesystem "Z:\\foo") |
| 370 | @end example |
| 371 | |
| 372 | @noindent |
| 373 | designates directory @file{\foo} on drive Z as an untranslated file |
| 374 | system. |
| 375 | |
| 376 | Most often you would use @code{add-untranslated-filesystem} in your |
| 377 | @file{_emacs} file, or in @file{site-start.el} so that all the users at |
| 378 | your site get the benefit of it. |
| 379 | |
| 380 | @findex remove-untranslated-filesystem |
| 381 | To countermand the effect of @code{add-untranslated-filesystem}, use |
| 382 | the function @code{remove-untranslated-filesystem}. This function takes |
| 383 | one argument, which should be a string just like the one that was used |
| 384 | previously with @code{add-untranslated-filesystem}. |
| 385 | |
| 386 | Designating a file system as untranslated does not affect character |
| 387 | set conversion, only end-of-line conversion. Essentially, it directs |
| 388 | Emacs to create new files with the Unix-style convention of using |
| 389 | newline at the end of a line. @xref{Coding Systems}. |
| 390 | |
| 391 | @vindex file-name-buffer-file-type-alist |
| 392 | @cindex binary files, on MS-DOS/MS-Windows |
| 393 | Some kinds of files should not be converted at all, because their |
| 394 | contents are not really text. Therefore, Emacs on MS-DOS distinguishes |
| 395 | certain files as @dfn{binary files}. (This distinction is not part of |
| 396 | MS-DOS; it is made by Emacs only.) Binary files include executable |
| 397 | programs, compressed archives, etc. Emacs uses the file name to decide |
| 398 | whether to treat a file as binary: the variable |
| 399 | @code{file-name-buffer-file-type-alist} defines the file-name patterns |
| 400 | that indicate binary files. If a file name matches one of the patterns |
| 401 | for binary files (those whose associations are of the type |
| 402 | @code{(@var{pattern} . t)}, Emacs reads and writes that file using the |
| 403 | @code{no-conversion} coding system (@pxref{Coding Systems}) which turns |
| 404 | off @emph{all} coding-system conversions, not only the EOL conversion. |
| 405 | @code{file-name-buffer-file-type-alist} also includes file-name patterns |
| 406 | for files which are known to be DOS-style text files with |
| 407 | carriage-return linefeed EOL format, such as @file{CONFIG.SYS}; Emacs |
| 408 | always writes those files with DOS-style EOLs. |
| 409 | |
| 410 | If a file which belongs to an untranslated file system matches one of |
| 411 | the file-name patterns in @code{file-name-buffer-file-type-alist}, the |
| 412 | EOL conversion is determined by @code{file-name-buffer-file-type-alist}. |
| 413 | |
| 414 | @node MS-DOS Printing |
| 415 | @section Printing and MS-DOS |
| 416 | |
| 417 | Printing commands, such as @code{lpr-buffer} (@pxref{Hardcopy}) and |
| 418 | @code{ps-print-buffer} (@pxref{PostScript}) can work in MS-DOS and |
| 419 | MS-Windows by sending the output to one of the printer ports, if a |
| 420 | Posix-style @code{lpr} program is unavailable. The same Emacs |
| 421 | variables control printing on all systems (@pxref{Hardcopy}), but in |
| 422 | some cases they have different default values on MS-DOS and |
| 423 | MS-Windows. |
| 424 | |
| 425 | @vindex printer-name @r{(MS-DOS)} |
| 426 | If you want to use your local printer, printing on it in the usual DOS |
| 427 | manner, then set the Lisp variable @code{lpr-command} to @code{""} (its |
| 428 | default value) and @code{printer-name} to the name of the printer |
| 429 | port---for example, @code{"PRN"}, the usual local printer port (that's |
| 430 | the default), or @code{"LPT2"}, or @code{"COM1"} for a serial printer. |
| 431 | You can also set @code{printer-name} to a file name, in which case |
| 432 | ``printed'' output is actually appended to that file. If you set |
| 433 | @code{printer-name} to @code{"NUL"}, printed output is silently |
| 434 | discarded (sent to the system null device). |
| 435 | |
| 436 | On MS-Windows, when the Windows network software is installed, you can |
| 437 | also use a printer shared by another machine by setting |
| 438 | @code{printer-name} to the UNC share name for that printer--for example, |
| 439 | @code{"//joes_pc/hp4si"}. (It doesn't matter whether you use forward |
| 440 | slashes or backslashes here.) To find out the names of shared printers, |
| 441 | run the command @samp{net view} at a DOS command prompt to obtain a list |
| 442 | of servers, and @samp{net view @var{server-name}} to see the names of printers |
| 443 | (and directories) shared by that server. Alternatively, click the |
| 444 | @samp{Network Neighborhood} icon on your desktop, and look for machines |
| 445 | which share their printers via the network. |
| 446 | |
| 447 | @cindex @samp{net use}, and printing on MS-Windows |
| 448 | @cindex networked printers (MS-Windows) |
| 449 | If the printer doesn't appear in the output of @samp{net view}, or |
| 450 | if setting @code{printer-name} to the UNC share name doesn't produce a |
| 451 | hardcopy on that printer, you can use the @samp{net use} command to |
| 452 | connect a local print port such as @code{"LPT2"} to the networked |
| 453 | printer. For example, typing @kbd{net use LPT2: |
| 454 | \\joes_pc\hp4si}@footnote{ |
| 455 | Note that the @samp{net use} command requires the UNC share name to be |
| 456 | typed with the Windows-style backslashes, while the value of |
| 457 | @code{printer-name} can be set with either forward- or backslashes.} |
| 458 | causes Windows to @dfn{capture} the LPT2 port and redirect the printed |
| 459 | material to the printer connected to the machine @code{joes_pc}. |
| 460 | After this command, setting @code{printer-name} to @code{"LPT2"} |
| 461 | should produce the hardcopy on the networked printer. |
| 462 | |
| 463 | With some varieties of Windows network software, you can instruct |
| 464 | Windows to capture a specific printer port such as @code{"LPT2"}, and |
| 465 | redirect it to a networked printer via the @w{@code{Control |
| 466 | Panel->Printers}} applet instead of @samp{net use}. |
| 467 | |
| 468 | Some printers expect DOS codepage encoding of non-ASCII text, even |
| 469 | though they are connected to a Windows machine which uses a different |
| 470 | encoding for the same locale. For example, in the Latin-1 locale, DOS |
| 471 | uses codepage 850 whereas Windows uses codepage 1252. @xref{MS-DOS and |
| 472 | MULE}. When you print to such printers from Windows, you can use the |
| 473 | @kbd{C-x RET c} (@code{universal-coding-system-argument}) command before |
| 474 | @kbd{M-x lpr-buffer}; Emacs will then convert the text to the DOS |
| 475 | codepage that you specify. For example, @kbd{C-x RET c cp850-dos RET |
| 476 | M-x lpr-region RET} will print the region while converting it to the |
| 477 | codepage 850 encoding. You may need to create the @code{cp@var{nnn}} |
| 478 | coding system with @kbd{M-x codepage-setup}. |
| 479 | |
| 480 | If you set @code{printer-name} to a file name, it's best to use an |
| 481 | absolute file name. Emacs changes the working directory according to |
| 482 | the default directory of the current buffer, so if the file name in |
| 483 | @code{printer-name} is relative, you will end up with several such |
| 484 | files, each one in the directory of the buffer from which the printing |
| 485 | was done. |
| 486 | |
| 487 | @findex print-buffer @r{(MS-DOS)} |
| 488 | @findex print-region @r{(MS-DOS)} |
| 489 | @vindex lpr-headers-switches @r{(MS-DOS)} |
| 490 | The commands @code{print-buffer} and @code{print-region} call the |
| 491 | @code{pr} program, or use special switches to the @code{lpr} program, to |
| 492 | produce headers on each printed page. MS-DOS and MS-Windows don't |
| 493 | normally have these programs, so by default, the variable |
| 494 | @code{lpr-headers-switches} is set so that the requests to print page |
| 495 | headers are silently ignored. Thus, @code{print-buffer} and |
| 496 | @code{print-region} produce the same output as @code{lpr-buffer} and |
| 497 | @code{lpr-region}, respectively. If you do have a suitable @code{pr} |
| 498 | program (for example, from GNU Textutils), set |
| 499 | @code{lpr-headers-switches} to @code{nil}; Emacs will then call |
| 500 | @code{pr} to produce the page headers, and print the resulting output as |
| 501 | specified by @code{printer-name}. |
| 502 | |
| 503 | @vindex print-region-function @r{(MS-DOS)} |
| 504 | @cindex lpr usage under MS-DOS |
| 505 | @vindex lpr-command @r{(MS-DOS)} |
| 506 | @vindex lpr-switches @r{(MS-DOS)} |
| 507 | Finally, if you do have an @code{lpr} work-alike, you can set the |
| 508 | variable @code{lpr-command} to @code{"lpr"}. Then Emacs will use |
| 509 | @code{lpr} for printing, as on other systems. (If the name of the |
| 510 | program isn't @code{lpr}, set @code{lpr-command} to specify where to |
| 511 | find it.) The variable @code{lpr-switches} has its standard meaning |
| 512 | when @code{lpr-command} is not @code{""}. If the variable |
| 513 | @code{printer-name} has a string value, it is used as the value for the |
| 514 | @code{-P} option to @code{lpr}, as on Unix. |
| 515 | |
| 516 | @findex ps-print-buffer @r{(MS-DOS)} |
| 517 | @findex ps-spool-buffer @r{(MS-DOS)} |
| 518 | @vindex ps-printer-name @r{(MS-DOS)} |
| 519 | @vindex ps-lpr-command @r{(MS-DOS)} |
| 520 | @vindex ps-lpr-switches @r{(MS-DOS)} |
| 521 | A parallel set of variables, @code{ps-lpr-command}, |
| 522 | @code{ps-lpr-switches}, and @code{ps-printer-name} (@pxref{PostScript |
| 523 | Variables}), defines how PostScript files should be printed. These |
| 524 | variables are used in the same way as the corresponding variables |
| 525 | described above for non-PostScript printing. Thus, the value of |
| 526 | @code{ps-printer-name} is used as the name of the device (or file) to |
| 527 | which PostScript output is sent, just as @code{printer-name} is used for |
| 528 | non-PostScript printing. (There are two distinct sets of variables in |
| 529 | case you have two printers attached to two different ports, and only one |
| 530 | of them is a PostScript printer.) |
| 531 | |
| 532 | The default value of the variable @code{ps-lpr-command} is @code{""}, |
| 533 | which causes PostScript output to be sent to the printer port specified |
| 534 | by @code{ps-printer-name}, but @code{ps-lpr-command} can also be set to |
| 535 | the name of a program which will accept PostScript files. Thus, if you |
| 536 | have a non-PostScript printer, you can set this variable to the name of |
| 537 | a PostScript interpreter program (such as Ghostscript). Any switches |
| 538 | that need to be passed to the interpreter program are specified using |
| 539 | @code{ps-lpr-switches}. (If the value of @code{ps-printer-name} is a |
| 540 | string, it will be added to the list of switches as the value for the |
| 541 | @code{-P} option. This is probably only useful if you are using |
| 542 | @code{lpr}, so when using an interpreter typically you would set |
| 543 | @code{ps-printer-name} to something other than a string so it is |
| 544 | ignored.) |
| 545 | |
| 546 | For example, to use Ghostscript for printing on an Epson printer |
| 547 | connected to the @samp{LPT2} port, put this in your @file{_emacs} file: |
| 548 | |
| 549 | @example |
| 550 | (setq ps-printer-name t) ; Ghostscript doesn't understand -P |
| 551 | (setq ps-lpr-command "c:/gs/gs386") |
| 552 | (setq ps-lpr-switches '("-q" "-dNOPAUSE" |
| 553 | "-sDEVICE=epson" |
| 554 | "-r240x72" |
| 555 | "-sOutputFile=LPT2" |
| 556 | "-Ic:/gs")) |
| 557 | @end example |
| 558 | |
| 559 | @noindent |
| 560 | (This assumes that Ghostscript is installed in the @file{"c:/gs"} |
| 561 | directory.) |
| 562 | |
| 563 | @vindex dos-printer |
| 564 | @vindex dos-ps-printer |
| 565 | For backwards compatibility, the value of @code{dos-printer} |
| 566 | (@code{dos-ps-printer}), if it has a value, overrides the value of |
| 567 | @code{printer-name} (@code{ps-printer-name}), on MS-DOS and MS-Windows |
| 568 | only. |
| 569 | |
| 570 | |
| 571 | @node MS-DOS and MULE |
| 572 | @section International Support on MS-DOS |
| 573 | @cindex international support @r{(MS-DOS)} |
| 574 | |
| 575 | Emacs on MS-DOS supports the same international character sets as it |
| 576 | does on GNU, Unix and other platforms (@pxref{International}), including |
| 577 | coding systems for converting between the different character sets. |
| 578 | However, due to incompatibilities between MS-DOS/MS-Windows and other systems, |
| 579 | there are several DOS-specific aspects of this support that you should |
| 580 | be aware of. This section describes these aspects. |
| 581 | |
| 582 | @table @kbd |
| 583 | @item M-x dos-codepage-setup |
| 584 | Set up Emacs display and coding systems as appropriate for the current |
| 585 | DOS codepage. |
| 586 | |
| 587 | @item M-x codepage-setup |
| 588 | Create a coding system for a certain DOS codepage. |
| 589 | @end table |
| 590 | |
| 591 | @cindex codepage, MS-DOS |
| 592 | @cindex DOS codepages |
| 593 | MS-DOS is designed to support one character set of 256 characters at |
| 594 | any given time, but gives you a variety of character sets to choose |
| 595 | from. The alternative character sets are known as @dfn{DOS codepages}. |
| 596 | Each codepage includes all 128 ASCII characters, but the other 128 |
| 597 | characters (codes 128 through 255) vary from one codepage to another. |
| 598 | Each DOS codepage is identified by a 3-digit number, such as 850, 862, |
| 599 | etc. |
| 600 | |
| 601 | In contrast to X, which lets you use several fonts at the same time, |
| 602 | MS-DOS normally doesn't allow use of several codepages in a single |
| 603 | session. MS-DOS was designed to load a single codepage at system |
| 604 | startup, and require you to reboot in order to change |
| 605 | it@footnote{Normally, one particular codepage is burnt into the display |
| 606 | memory, while other codepages can be installed by modifying system |
| 607 | configuration files, such as @file{CONFIG.SYS}, and rebooting. While |
| 608 | third-party software is known to exist that allows to change the |
| 609 | codepage without rebooting, we describe here how a stock MS-DOS system |
| 610 | behaves.}. Much the same limitation applies when you run DOS |
| 611 | executables on other systems such as MS-Windows. |
| 612 | |
| 613 | @cindex unibyte operation @r{(MS-DOS)} |
| 614 | If you invoke Emacs on MS-DOS with the @samp{--unibyte} option |
| 615 | (@pxref{Initial Options}), Emacs does not perform any conversion of |
| 616 | non-ASCII characters. Instead, it reads and writes any non-ASCII |
| 617 | characters verbatim, and sends their 8-bit codes to the display |
| 618 | verbatim. Thus, unibyte Emacs on MS-DOS supports the current codepage, |
| 619 | whatever it may be, but cannot even represent any other characters. |
| 620 | |
| 621 | @vindex dos-codepage |
| 622 | For multibyte operation on MS-DOS, Emacs needs to know which |
| 623 | characters the chosen DOS codepage can display. So it queries the |
| 624 | system shortly after startup to get the chosen codepage number, and |
| 625 | stores the number in the variable @code{dos-codepage}. Some systems |
| 626 | return the default value 437 for the current codepage, even though the |
| 627 | actual codepage is different. (This typically happens when you use the |
| 628 | codepage built into the display hardware.) You can specify a different |
| 629 | codepage for Emacs to use by setting the variable @code{dos-codepage} in |
| 630 | your init file. |
| 631 | |
| 632 | @cindex language environment, automatic selection on @r{MS-DOS} |
| 633 | Multibyte Emacs supports only certain DOS codepages: those which can |
| 634 | display Far-Eastern scripts, like the Japanese codepage 932, and those |
| 635 | that encode a single ISO 8859 character set. |
| 636 | |
| 637 | The Far-Eastern codepages can directly display one of the MULE |
| 638 | character sets for these countries, so Emacs simply sets up to use the |
| 639 | appropriate terminal coding system that is supported by the codepage. |
| 640 | The special features described in the rest of this section mostly |
| 641 | pertain to codepages that encode ISO 8859 character sets. |
| 642 | |
| 643 | For the codepages which correspond to one of the ISO character sets, |
| 644 | Emacs knows the character set name based on the codepage number. Emacs |
| 645 | automatically creates a coding system to support reading and writing |
| 646 | files that use the current codepage, and uses this coding system by |
| 647 | default. The name of this coding system is @code{cp@var{nnn}}, where |
| 648 | @var{nnn} is the codepage number.@footnote{The standard Emacs coding |
| 649 | systems for ISO 8859 are not quite right for the purpose, because |
| 650 | typically the DOS codepage does not match the standard ISO character |
| 651 | codes. For example, the letter @samp{@,{c}} (@samp{c} with cedilla) has |
| 652 | code 231 in the standard Latin-1 character set, but the corresponding |
| 653 | DOS codepage 850 uses code 135 for this glyph.} |
| 654 | |
| 655 | @cindex mode line @r{(MS-DOS)} |
| 656 | All the @code{cp@var{nnn}} coding systems use the letter @samp{D} (for |
| 657 | ``DOS'') as their mode-line mnemonic. Since both the terminal coding |
| 658 | system and the default coding system for file I/O are set to the proper |
| 659 | @code{cp@var{nnn}} coding system at startup, it is normal for the mode |
| 660 | line on MS-DOS to begin with @samp{-DD\-}. @xref{Mode Line}. |
| 661 | Far-Eastern DOS terminals do not use the @code{cp@var{nnn}} coding |
| 662 | systems, and thus their initial mode line looks like the Emacs default. |
| 663 | |
| 664 | Since the codepage number also indicates which script you are using, |
| 665 | Emacs automatically runs @code{set-language-environment} to select the |
| 666 | language environment for that script (@pxref{Language Environments}). |
| 667 | |
| 668 | If a buffer contains a character belonging to some other ISO 8859 |
| 669 | character set, not the one that the chosen DOS codepage supports, Emacs |
| 670 | displays it using a sequence of ASCII characters. For example, if the |
| 671 | current codepage doesn't have a glyph for the letter @samp{@`o} (small |
| 672 | @samp{o} with a grave accent), it is displayed as @samp{@{`o@}}, where |
| 673 | the braces serve as a visual indication that this is a single character. |
| 674 | (This may look awkward for some non-Latin characters, such as those from |
| 675 | Greek or Hebrew alphabets, but it is still readable by a person who |
| 676 | knows the language.) Even though the character may occupy several |
| 677 | columns on the screen, it is really still just a single character, and |
| 678 | all Emacs commands treat it as one. |
| 679 | |
| 680 | @cindex IBM graphics characters (MS-DOS) |
| 681 | @cindex box-drawing characters (MS-DOS) |
| 682 | @cindex line-drawing characters (MS-DOS) |
| 683 | Not all characters in DOS codepages correspond to ISO 8859 |
| 684 | characters---some are used for other purposes, such as box-drawing |
| 685 | characters and other graphics. Emacs maps these characters to two |
| 686 | special character sets called @code{eight-bit-control} and |
| 687 | @code{eight-bit-graphic}, and displays them as their IBM glyphs. |
| 688 | However, you should be aware that other systems might display these |
| 689 | characters differently, so you should avoid them in text that might be |
| 690 | copied to a different operating system, or even to another DOS machine |
| 691 | that uses a different codepage. |
| 692 | |
| 693 | @vindex dos-unsupported-character-glyph |
| 694 | Emacs supports many other characters sets aside from ISO 8859, but it |
| 695 | cannot display them on MS-DOS. So if one of these multibyte characters |
| 696 | appears in a buffer, Emacs on MS-DOS displays them as specified by the |
| 697 | @code{dos-unsupported-character-glyph} variable; by default, this glyph |
| 698 | is an empty triangle. Use the @kbd{C-u C-x =} command to display the |
| 699 | actual code and character set of such characters. @xref{Position Info}. |
| 700 | |
| 701 | @findex codepage-setup |
| 702 | By default, Emacs defines a coding system to support the current |
| 703 | codepage. To define a coding system for some other codepage (e.g., to |
| 704 | visit a file written on a DOS machine in another country), use the |
| 705 | @kbd{M-x codepage-setup} command. It prompts for the 3-digit code of |
| 706 | the codepage, with completion, then creates the coding system for the |
| 707 | specified codepage. You can then use the new coding system to read and |
| 708 | write files, but you must specify it explicitly for the file command |
| 709 | when you want to use it (@pxref{Specify Coding}). |
| 710 | |
| 711 | These coding systems are also useful for visiting a file encoded using |
| 712 | a DOS codepage, using Emacs running on some other operating system. |
| 713 | |
| 714 | @cindex MS-Windows codepages |
| 715 | MS-Windows provides its own codepages, which are different from the |
| 716 | DOS codepages for the same locale. For example, DOS codepage 850 |
| 717 | supports the same character set as Windows codepage 1252; DOS codepage |
| 718 | 855 supports the same character set as Windows codepage 1251, etc. |
| 719 | The MS-Windows version of Emacs uses the current codepage for display |
| 720 | when invoked with the @samp{-nw} option. |
| 721 | |
| 722 | @node MS-DOS Processes |
| 723 | @section Subprocesses on MS-DOS |
| 724 | |
| 725 | @cindex compilation under MS-DOS |
| 726 | @cindex inferior processes under MS-DOS |
| 727 | @findex compile @r{(MS-DOS)} |
| 728 | @findex grep @r{(MS-DOS)} |
| 729 | Because MS-DOS is a single-process ``operating system,'' |
| 730 | asynchronous subprocesses are not available. In particular, Shell |
| 731 | mode and its variants do not work. Most Emacs features that use |
| 732 | asynchronous subprocesses also don't work on MS-DOS, including |
| 733 | Shell mode and GUD. When in doubt, try and see; commands that |
| 734 | don't work output an error message saying that asynchronous processes |
| 735 | aren't supported. |
| 736 | |
| 737 | Compilation under Emacs with @kbd{M-x compile}, searching files with |
| 738 | @kbd{M-x grep} and displaying differences between files with @kbd{M-x |
| 739 | diff} do work, by running the inferior processes synchronously. This |
| 740 | means you cannot do any more editing until the inferior process |
| 741 | finishes. |
| 742 | |
| 743 | Spell checking also works, by means of special support for synchronous |
| 744 | invocation of the @code{ispell} program. This is slower than the |
| 745 | asynchronous invocation on other platforms |
| 746 | |
| 747 | Instead of the Shell mode, which doesn't work on MS-DOS, you can use |
| 748 | the @kbd{M-x eshell} command. This invokes the Eshell package that |
| 749 | implements a Posix-like shell entirely in Emacs Lisp. |
| 750 | |
| 751 | By contrast, Emacs compiled as native Windows application |
| 752 | @strong{does} support asynchronous subprocesses. @xref{Windows |
| 753 | Processes}. |
| 754 | |
| 755 | @cindex printing under MS-DOS |
| 756 | Printing commands, such as @code{lpr-buffer} (@pxref{Hardcopy}) and |
| 757 | @code{ps-print-buffer} (@pxref{PostScript}), work in MS-DOS by sending |
| 758 | the output to one of the printer ports. @xref{MS-DOS Printing}. |
| 759 | |
| 760 | When you run a subprocess synchronously on MS-DOS, make sure the |
| 761 | program terminates and does not try to read keyboard input. If the |
| 762 | program does not terminate on its own, you will be unable to terminate |
| 763 | it, because MS-DOS provides no general way to terminate a process. |
| 764 | Pressing @kbd{C-c} or @kbd{C-@key{BREAK}} might sometimes help in these |
| 765 | cases. |
| 766 | |
| 767 | Accessing files on other machines is not supported on MS-DOS. Other |
| 768 | network-oriented commands such as sending mail, Web browsing, remote |
| 769 | login, etc., don't work either, unless network access is built into |
| 770 | MS-DOS with some network redirector. |
| 771 | |
| 772 | @cindex directory listing on MS-DOS |
| 773 | @vindex dired-listing-switches @r{(MS-DOS)} |
| 774 | Dired on MS-DOS uses the @code{ls-lisp} package where other |
| 775 | platforms use the system @code{ls} command. Therefore, Dired on |
| 776 | MS-DOS supports only some of the possible options you can mention in |
| 777 | the @code{dired-listing-switches} variable. The options that work are |
| 778 | @samp{-A}, @samp{-a}, @samp{-c}, @samp{-i}, @samp{-r}, @samp{-S}, |
| 779 | @samp{-s}, @samp{-t}, and @samp{-u}. |
| 780 | |
| 781 | @node Windows Processes |
| 782 | @section Subprocesses on Windows 9X/ME and Windows NT/2K |
| 783 | |
| 784 | Emacs compiled as a native Windows application (as opposed to the DOS |
| 785 | version) includes full support for asynchronous subprocesses. |
| 786 | In the Windows version, synchronous and asynchronous subprocesses work |
| 787 | fine on both |
| 788 | Windows 9X and Windows NT/2K as long as you run only 32-bit Windows |
| 789 | applications. However, when you run a DOS application in a subprocess, |
| 790 | you may encounter problems or be unable to run the application at all; |
| 791 | and if you run two DOS applications at the same time in two |
| 792 | subprocesses, you may have to reboot your system. |
| 793 | |
| 794 | Since the standard command interpreter (and most command line utilities) |
| 795 | on Windows 95 are DOS applications, these problems are significant when |
| 796 | using that system. But there's nothing we can do about them; only |
| 797 | Microsoft can fix them. |
| 798 | |
| 799 | If you run just one DOS application subprocess, the subprocess should |
| 800 | work as expected as long as it is ``well-behaved'' and does not perform |
| 801 | direct screen access or other unusual actions. If you have a CPU |
| 802 | monitor application, your machine will appear to be 100% busy even when |
| 803 | the DOS application is idle, but this is only an artifact of the way CPU |
| 804 | monitors measure processor load. |
| 805 | |
| 806 | You must terminate the DOS application before you start any other DOS |
| 807 | application in a different subprocess. Emacs is unable to interrupt or |
| 808 | terminate a DOS subprocess. The only way you can terminate such a |
| 809 | subprocess is by giving it a command that tells its program to exit. |
| 810 | |
| 811 | If you attempt to run two DOS applications at the same time in separate |
| 812 | subprocesses, the second one that is started will be suspended until the |
| 813 | first one finishes, even if either or both of them are asynchronous. |
| 814 | |
| 815 | If you can go to the first subprocess, and tell it to exit, the second |
| 816 | subprocess should continue normally. However, if the second subprocess |
| 817 | is synchronous, Emacs itself will be hung until the first subprocess |
| 818 | finishes. If it will not finish without user input, then you have no |
| 819 | choice but to reboot if you are running on Windows 9X. If you are |
| 820 | running on Windows NT/2K, you can use a process viewer application to kill |
| 821 | the appropriate instance of ntvdm instead (this will terminate both DOS |
| 822 | subprocesses). |
| 823 | |
| 824 | If you have to reboot Windows 9X in this situation, do not use the |
| 825 | @code{Shutdown} command on the @code{Start} menu; that usually hangs the |
| 826 | system. Instead, type @kbd{CTL-ALT-@key{DEL}} and then choose |
| 827 | @code{Shutdown}. That usually works, although it may take a few minutes |
| 828 | to do its job. |
| 829 | |
| 830 | @node Windows System Menu |
| 831 | @section Using the System Menu on Windows |
| 832 | |
| 833 | Emacs compiled as a native Windows application normally turns off the |
| 834 | Windows feature that tapping the @key{ALT} |
| 835 | key invokes the Windows menu. The reason is that the @key{ALT} also |
| 836 | serves as @key{META} in Emacs. When using Emacs, users often press the |
| 837 | @key{META} key temporarily and then change their minds; if this has the |
| 838 | effect of bringing up the Windows menu, it alters the meaning of |
| 839 | subsequent commands. Many users find this frustrating. |
| 840 | |
| 841 | @vindex w32-pass-alt-to-system |
| 842 | You can reenable Windows's default handling of tapping the @key{ALT} key |
| 843 | by setting @code{w32-pass-alt-to-system} to a non-@code{nil} value. |
| 844 | |