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I.1 How to Start Emacs on MS-Windows ¶

There are several ways of starting Emacs on MS-Windows:

1. From the desktop shortcut icon: either double-click the left mouse button on the icon, or click once, then press RET. The desktop shortcut should specify as its “Target” (in the “Properties” of the shortcut) the full absolute file name of runemacs.exe, not of emacs.exe. This is because runemacs.exe hides the console window that would have been created if the target of the shortcut were emacs.exe (which is a console program, as far as Windows is concerned). If you use this method, Emacs starts in the directory specified by the shortcut. To control where that is, right-click on the shortcut, select “Properties”, and in the “Shortcut” tab modify the “Start in” field to your liking.
2. From a task-bar shortcut icon, by clicking once the left mouse button. Windows versions since Vista allow you to create such shortcuts by pinning the icon of a running program that appears in the task bar. You can do that with Emacs, but afterwards you will have to change the properties of the pinned shortcut to run runemacs.exe, not of emacs.exe. You can also pin Emacs to the task bar by clicking the right mouse button on its icon in the Start menu, then selecting ‘Pin to taskbar’. Once again, be sure to specify runemacs.exe as the program to run. You can control where Emacs starts by setting the “Start in” field of the shortcut’s Properties.
3. From the Command Prompt window, by typing emacs RET at the prompt. The Command Prompt window where you did that will not be available for invoking other commands until Emacs exits. In this case, Emacs will start in the current directory of the Windows shell.
4. From the Command Prompt window, by typing runemacs RET at the prompt. The Command Prompt window where you did that will be immediately available for invoking other commands. In this case, Emacs will start in the current directory of the Windows shell.
5. From the Windows Run dialog (normally reached by clicking the Start button). Typing runemacs RET into the dialog will start Emacs in the parent directory of the Windows equivalent of your user’s HOME directory, see HOME and Startup Directories on MS-Windows.
6. Via emacsclient.exe or emacsclientw.exe, which allow you to invoke Emacs from other programs, and to reuse a running Emacs process for serving editing jobs required by other programs. See Using Emacs as a Server. The difference between emacsclient.exe and emacsclientw.exe is that the former is a console program, while the latter is a Windows GUI program. Both programs wait for Emacs to signal that the editing job is finished, before they exit and return control to the program that invoked them. Which one of them to use in each case depends on the expectations of the program that needs editing services. If that program is itself a console (text-mode) program, you should use emacsclient.exe, so that any of its messages and prompts appear in the same command window as those of the invoking program. By contrast, if the invoking program is a GUI program, you will be better off using emacsclientw.exe, because emacsclient.exe will pop up a command window if it is invoked from a GUI program. A notable situation where you would want emacsclientw.exe is when you right-click on a file in the Windows Explorer and select “Open With” from the pop-up menu. Use the ‘--alternate-editor=’ or ‘-a’ options if Emacs might not be running (or not running as a server) when emacsclient is invoked—that will always give you an editor. When invoked via emacsclient, Emacs will start in the current directory of the program that invoked emacsclient.

Note that, due to limitations of MS-Windows, Emacs cannot have both GUI and text-mode frames in the same session. It also cannot open text-mode frames on more than a single Command Prompt window, because each Windows program can have only one console at any given time. For these reasons, if you invoke emacsclient with the -c option, and the Emacs server runs in a text-mode session, Emacs will always create a new text-mode frame in the same Command Prompt window where it was started; a GUI frame will be created only if the server runs in a GUI session. Similarly, if you invoke emacsclient with the -t option, Emacs will create a GUI frame if the server runs in a GUI session, or a text-mode frame when the session runs in text mode in a Command Prompt window. See emacsclient Options.

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I.2 Text Files and Binary Files ¶

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

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

One consequence of this special format-conversion of most files is that character positions as reported by Emacs (see Cursor Position Information) do not agree with the file size information known to the operating system.

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

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

To visit a file and specify whether it uses DOS-style or Unix-style end-of-line, specify a coding system (see Specifying a Coding System for File Text). For example, C-x RET c unix RET C-x C-f foobar.txt visits the file foobar.txt without converting the EOLs; if some line ends with a carriage return followed by linefeed pair, Emacs will display ‘^M’ at the end of that line. Similarly, you can direct Emacs to save a buffer in a specified EOL format with the C-x RET f command. For example, to save a buffer with Unix EOL format, type C-x RET f unix RET C-x C-s. If you visit a file with DOS EOL conversion, then save it with Unix EOL format, that effectively converts the file to Unix EOL style, like the dos2unix program.

When you use NFS, Samba, or some other similar method to access file systems that reside on computers using GNU or Unix systems, Emacs should not perform end-of-line translation on any files in these file systems—not even when you create a new file. To request this, designate these file systems as untranslated file systems by calling the function w32-add-untranslated-filesystem. It takes one argument: the file system name, including a drive letter and optionally a directory. For example,

(w32-add-untranslated-filesystem "Z:")

designates drive Z as an untranslated file system, and

(w32-add-untranslated-filesystem "Z:\\foo")

designates directory \foo on drive Z as an untranslated file system.

Most often you would use w32-add-untranslated-filesystem in your .emacs or init.el init file, or in site-start.el so that all the users at your site get the benefit of it.

To countermand the effect of w32-add-untranslated-filesystem, use the function w32-remove-untranslated-filesystem. This function takes one argument, which should be a string just like the one that was used previously with w32-add-untranslated-filesystem.

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

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I.3 File Names on MS-Windows ¶

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

On MS-DOS/MS-Windows, file names are case-insensitive, so Emacs by default ignores letter-case in file names during completion. To this end, the default value of read-file-name-completion-ignore-case is non-nil on MS-DOS/MS-Windows. See Completion Options.

The variable w32-get-true-file-attributes controls whether Emacs should issue additional system calls to determine more accurately file attributes in primitives like file-attributes and directory-files-and-attributes. These additional calls are needed to report correct file ownership, link counts and file types for special files such as pipes. Without these system calls, file ownership will be attributed to the current user, link counts will be always reported as 1, and special files will be reported as regular files.

If the value of this variable is local (the default), Emacs will issue these additional system calls only for files on local fixed drives. Any other non-nil value means do this even for removable and remote volumes, where this could potentially slow down Dired and other related features. The value of nil means never issue those system calls. Non-nil values are more useful on NTFS volumes, which support hard links and file security, than on FAT, FAT32, and exFAT volumes.

Unlike Unix, MS-Windows file systems restrict the set of characters that can be used in a file name. The following characters are not allowed:

• Shell redirection symbols ‘<’, ‘>’, and ‘|’.
• Colon ‘:’ (except after the drive letter).
• Forward slash ‘/’ and backslash ‘\’ (except as directory separators).
• Wildcard characters ‘*’ and ‘?’.
• Control characters whose codepoints are 1 through 31 decimal. In particular, newlines in file names are not allowed.
• The null character, whose codepoint is zero (this limitation exists on Unix filesystems as well).

In addition, referencing any file whose name matches a DOS character device, such as NUL or LPT1 or PRN or CON, with or without any file-name extension, will always resolve to those character devices, in any directory. Therefore, only use such file names when you want to use the corresponding character device.

Next: HOME and Startup Directories on MS-Windows, Previous: File Names on MS-Windows, Up: Emacs and Microsoft Windows/MS-DOS   [Contents][Index]

I.4 Emulation of ls on MS-Windows ¶

Dired normally uses the external program ls to produce the directory listing displayed in Dired buffers (see Dired, the Directory Editor). However, MS-Windows and MS-DOS systems don’t come with such a program, although several ports of GNU ls are available. Therefore, Emacs on those systems emulates ls in Lisp, by using the ls-lisp.el package. While ls-lisp.el provides a reasonably full emulation of ls, there are some options and features peculiar to that emulation; they are described in this section.

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

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

The order in which ls-lisp.el sorts files depends on several customizable options described below.

The default sorting order follows locale-specific rules derived from your system locale. You can make the order locale-independent by customizing ls-lisp-use-string-collate to a nil value.

On GNU and Unix systems, when the locale’s encoding is UTF-8, the collation order follows the Unicode Collation Algorithm (UCA). To have a similar effect on MS-Windows, the variable ls-lisp-UCA-like-collation should have a non-nil value (this is the default). The resulting sorting order ignores punctuation, symbol characters, and whitespace characters, so .foobar, foobar and foo bar will appear together rather than far apart.

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

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

The variable ls-lisp-verbosity controls the file attributes that ls-lisp.el displays. The value should be either nil or a list that contains one or more of the symbols links, uid, and gid. links means display the count of different file names that are associated with (a.k.a. links to) the file’s data; this is only useful on NTFS volumes. uid means display the numerical identifier of the user who owns the file. gid means display the numerical identifier of the file owner’s group. The default value is (links uid gid) i.e., all the 3 optional attributes are displayed. The value nil means not to display any of these attributes.

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

GNU

nil

Emulate GNU systems; this is the default. This sets ls-lisp-ignore-case and ls-lisp-dirs-first to nil, and ls-lisp-verbosity to (links uid gid modes).

UNIX

Emulate Unix systems. Like GNU, but sets ls-lisp-verbosity to (links uid modes).

MacOS

Emulate macOS. Sets ls-lisp-ignore-case to t, and ls-lisp-dirs-first and ls-lisp-verbosity to nil.

MS-Windows

Emulate MS-Windows. Sets ls-lisp-ignore-case and ls-lisp-dirs-first to t, and ls-lisp-verbosity to nil on Windows 9X and to t on modern versions of Windows. Note that the default emulation is not MS-Windows, even on Windows, since many users of Emacs on those platforms prefer the GNU defaults.

Any other value of ls-lisp-emulation means the same as GNU. Customizing this option calls the function ls-lisp-set-options to update the 3 dependent options as needed. If you change the value of this variable without using customize after ls-lisp.el is loaded (note that it is preloaded on MS-Windows and MS-DOS), you can call that function manually for the same result.

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

The variable ls-lisp-format-time-list defines how to format the date and time of files. The value of this variable is ignored, unless Emacs cannot determine the current locale. (However, if the value of ls-lisp-use-localized-time-format is non-nil, Emacs obeys ls-lisp-format-time-list even if the current locale is available; see below.)

The value of ls-lisp-format-time-list is a list of 2 strings. The first string is used if the file was modified within the current year, while the second string is used for older files. In each of these two strings you can use ‘%’-sequences to substitute parts of the time. For example:

("%b %e %H:%M" "%b %e  %Y")

Note that the strings substituted for these ‘%’-sequences depend on the current locale. See Time Parsing in The Emacs Lisp Reference Manual, for more about format time specs.

Normally, Emacs formats the file time stamps in either traditional or ISO-style time format. However, if the value of the variable ls-lisp-use-localized-time-format is non-nil, Emacs formats file time stamps according to what ls-lisp-format-time-list specifies. The ‘%’-sequences in ls-lisp-format-time-list produce locale-dependent month and day names, which might cause misalignment of columns in Dired display. The default value of ls-lisp-use-localized-time-format is nil.

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I.5 HOME and Startup Directories on MS-Windows ¶

The Windows equivalent of HOME is the user-specific application data directory. The actual location depends on the Windows version; typical values are C:\Documents and Settings\username\Application Data on Windows 2000 up to XP, C:\Users\username\AppData\Roaming on Windows Vista and later, and either C:\WINDOWS\Application Data or C:\WINDOWS\Profiles\username\Application Data on Windows 9X/ME. If this directory does not exist or cannot be accessed, Emacs falls back to C:\ as the default value of HOME.

You can override this default value of HOME by explicitly setting the environment variable HOME to point to any directory on your system. HOME can be set either from the command shell prompt or from ‘Properties’ dialog of ‘My Computer’. HOME can also be set in the system registry, see The MS-Windows System Registry.

For compatibility with older versions of Emacs⁴², if there is a file named .emacs in C:\, the root directory of drive C:, and HOME is set neither in the environment nor in the Registry, Emacs will treat C:\ as the default HOME location, and will not look in the application data directory, even if it exists. Note that only .emacs is looked for in C:\; the older name _emacs (see below) is not. This use of C:\.emacs to define HOME is deprecated; Emacs will display a warning about its use during startup.

Whatever the final place is, Emacs sets the internal value of the HOME environment variable to point to it, and it will use that location for other files and directories it normally looks for or creates in your home directory.

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

Your init file can have any name mentioned in The Emacs Initialization File.

Because MS-DOS does not allow file names with leading dots, and older Windows systems made it hard to create files with such names, the Windows port of Emacs supports an init file name _emacs, if such a file exists in the home directory and .emacs does not. This name is considered obsolete, so Emacs will display a warning if it is used.

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I.6 Keyboard Usage on MS-Windows ¶

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

Many key combinations (known as “keyboard shortcuts”) that have conventional uses in MS-Windows programs conflict with traditional Emacs key bindings. (These Emacs key bindings were established years before Microsoft was founded.) Examples of conflicts include C-c, C-x, C-z, and C-a. You can redefine some of them with meanings more like the MS-Windows meanings by enabling CUA Mode (see CUA Bindings). Another optional feature which will make Emacs behave like other Windows applications is Delete Selection mode (see Operating on the Region).

By default, the key labeled Alt is mapped as the Meta key. If you wish it to produce the Alt modifier instead, set the variable w32-alt-is-meta to a nil value.

MS-Windows reserves certain key combinations, such as Alt-TAB and a number of Windows key combinations, for its own use. These key combinations are intercepted by the system before Emacs can see them. Also, on Windows 10, all Windows key combinations are reserved by the system in such a way that they are never propagated to applications, even if the system does not currently define a hotkey on the specific combination. You can use the w32-register-hot-key function to allow a key sequence to be seen by Emacs instead of being grabbed by Windows. When registered as a hot key, the key combination is pulled out of the system’s input queue before it is handled by Windows, effectively overriding the special meaning of that key sequence for Windows. The override is only effective when Emacs is active; with other applications on the foreground the keys behave normally.

The argument to w32-register-hot-key must be a single key with a single modifier, in vector form that would be acceptable to define-key. The control and shift modifiers have no effect on the argument. The meta modifier is interpreted as the Alt key if w32-alt-is-meta is t (the default), and the super and hyper modifiers are interpreted according to the bindings of w32-lwindow-modifier and w32-rwindow-modifier. Additionally, a modifier with the trailing dash but with no key indicates that all Windows defined hotkeys for that modifier are to be overridden in the favor of Emacs.

For example, (w32-register-hot-key [M-tab]) lets you use M-TAB normally in Emacs; for instance, to complete the word or symbol at point at top level, or to complete the current search string against previously sought strings during incremental search. (w32-register-hot-key [s-]) with w32-lwindow-modifier bound to super disables all the Windows’ own Windows key based shortcuts.⁴³

Note that w32-register-hot-key checks the w32-[lr]window-modifier values at the time of the function call. Thus, you can set w32-lwindow-modifier as super, then call (w32-register-hot-key [s-r]), and finally set w32-rwindow-modifier as super as well. The result is that the left Windows key together with R invokes whichever function you have bound for the combination in Emacs, and the right Windows key and R opens the Windows Run dialog.

The hotkey registrations always also include all the shift and control modifier combinations for the given hotkey; that is, registering s-a as a hotkey gives you S-s-a, C-s-a and C-S-s-a as well.

On Windows 98 and ME, the hotkey registration is more restricted. The desired hotkey must always be fully specified, and w32-phantom-key-code can be customized to achieve desired results.

The function w32-unregister-hot-key reverses the effect of w32-register-hot-key for its argument key sequence.

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

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

Similarly, if w32-enable-num-lock is nil, the NumLock key will produce the symbol kp-numlock. The default is t, which causes NumLock to work as expected: toggle the meaning of the keys on the numeric keypad.

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

The variable w32-lwindow-modifier determines the effect of the left Windows key (usually labeled with start and the Windows logo). If its value is nil (the default), the key will produce the symbol lwindow. Setting it to one of the symbols hyper, super, meta, alt, control, or shift will produce the respective modifier. A similar variable w32-rwindow-modifier controls the effect of the right Windows key, and w32-scroll-lock-modifier does the same for the ScrLock key. If these variables are set to nil, the right Windows key produces the symbol rwindow and ScrLock produces the symbol scroll. If you want ScrLock to produce the same effect as in other applications, i.e. toggle the Scroll Lock LED indication on the keyboard, set w32-scroll-lock-modifier to t or any non-nil value other than the above modifier symbols.

Emacs compiled as a native Windows application normally turns off the Windows feature that tapping the Alt key invokes the Windows menu. The reason is that the Alt serves as Meta in Emacs. When using Emacs, users often press the Meta key temporarily and then change their minds; if this has the effect of bringing up the Windows menu, it alters the meaning of subsequent commands. Many users find this frustrating.

You can re-enable Windows’s default handling of tapping the Alt key by setting w32-pass-alt-to-system to a non-nil value.

The variables w32-pass-lwindow-to-system and w32-pass-rwindow-to-system determine whether the respective keys are passed to Windows or swallowed by Emacs. If the value is nil, the respective key is silently swallowed by Emacs, otherwise it is passed to Windows. The default is t for both of these variables. Passing each of these keys to Windows produces its normal effect: for example, Lwindow opens the Start menu, etc.

The variable w32-recognize-altgr controls whether the AltGr key (if it exists on your keyboard), or its equivalent, the combination of the right Alt and left Ctrl keys pressed together, is recognized as the AltGr key. The default is t, which means these keys produce AltGr; setting it to nil causes AltGr or the equivalent key combination to be interpreted as the combination of Ctrl and Meta modifiers.

Some versions of MS-Windows, typically East Asian localized Windows, enable the Input Method Manager (IMM) that allows applications to communicate with the Input Method Editor (IME), the native Windows input method service. Emacs uses the IME when available to allow users to input East Asian non-ASCII characters, similarly to Emacs’s built-in input methods (see Input Methods). However, in some situations the IME can get in the way if it interprets simple ASCII keys you input as part of a key sequence that designates a non-ASCII character. The IME can be temporarily turned off and then on again by using the w32-set-ime-open-status function.

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I.7 Mouse Usage on MS-Windows ¶

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

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

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

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

Next: Printing and MS-Windows, Previous: Mouse Usage on MS-Windows, Up: Emacs and Microsoft Windows/MS-DOS   [Contents][Index]

I.8 Subprocesses on Windows 9X/ME and Windows NT/2K/XP/Vista/7/8/10 ¶

Emacs compiled as a native Windows application (as opposed to the DOS version) includes full support for asynchronous subprocesses. In the Windows version, synchronous and asynchronous subprocesses work fine on all versions of MS-Windows, as long as you run only 32-bit or 64-bit Windows applications. However, when you run a DOS application in a subprocess, you may encounter problems or be unable to run the application at all; and if you run two DOS applications at the same time in two subprocesses, you may have to reboot your system.

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

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

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

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

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

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

The variable w32-quote-process-args controls how Emacs quotes the process arguments. Non-nil means quote with the " character. If the value is a character, Emacs uses that character to escape any quote characters that appear; otherwise it chooses a suitable escape character based on the type of the program.

The variable w32-pipe-buffer-size controls the size of the buffer Emacs requests from the system when it creates pipes for communications with subprocesses. The default value is zero, which lets the OS choose the size. Any valid positive value will request a buffer of that size in bytes. This can be used to tailor communications with subprocesses to programs that exhibit unusual behavior with respect to buffering pipe I/O.

If you need to invoke MS-DOS programs as Emacs subprocesses, you may see low rate of reading data from such programs. Setting the variable w32-pipe-read-delay to a non-zero value may improve throughput in these cases; we suggest the value of 50 for such situations. The default is zero.

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

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I.9 Printing and MS-Windows ¶

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

Emacs on MS Windows attempts to determine your default printer automatically (using the function default-printer-name). But in some rare cases this can fail, or you may wish to use a different printer from within Emacs. The rest of this section explains how to tell Emacs which printer to use.

If you want to use your local printer, then set the Lisp variable lpr-command to "" (its default value on Windows) and printer-name to the name of the printer port—for example, "PRN", the usual local printer port, or "LPT2", or "COM1" for a serial printer. You can also set printer-name to a file name, in which case “printed” output is actually appended to that file. If you set printer-name to "NUL", printed output is silently discarded (sent to the system null device).

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

If the printer doesn’t appear in the output of ‘net view’, or if setting printer-name to the UNC share name doesn’t produce a hardcopy on that printer, you can use the ‘net use’ command to connect a local print port such as "LPT2" to the networked printer. For example, typing net use LPT2: \\joes_pc\hp4si⁴⁴ causes Windows to capture the LPT2 port and redirect the printed material to the printer connected to the machine joes_pc. After this command, setting printer-name to "LPT2" should produce the hardcopy on the networked printer.

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

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

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

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

Finally, if you do have an lpr work-alike, you can set the variable lpr-command to "lpr". Then Emacs will use lpr for printing, as on other systems. (If the name of the program isn’t lpr, set lpr-command to the appropriate value.) The variable lpr-switches has its standard meaning when lpr-command is not "". If the variable printer-name has a string value, it is used as the value for the -P option to lpr, as on Unix.

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

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

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

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

(This assumes that Ghostscript is installed in the D:/gs6.01 directory.)

Next: Miscellaneous Windows-specific features, Previous: Printing and MS-Windows, Up: Emacs and Microsoft Windows/MS-DOS   [Contents][Index]

I.10 Specifying Fonts on MS-Windows ¶

Fonts are specified by their name, size and optional properties. The format for specifying fonts comes from the fontconfig library used in modern Free desktops:

  [Family[-PointSize]][:Option1=Value1[:Option2=Value2[...]]]

The old XLFD based format is also supported for backwards compatibility.

Emacs on MS-Windows supports a number of font backends. Currently, the gdi, uniscribe, and harfbuzz backends are available. The gdi font backend is available on all versions of Windows, and supports all fonts that are natively supported by Windows. The uniscribe font backend is available on Windows 2000 and later, and supports TrueType and OpenType fonts. The harfbuzz font backend is available if Emacs was built with HarfBuzz support, and if the HarfBuzz DLL is installed on your system; like uniscribe, this backend supports only TrueType and OpenType fonts. Some languages requiring complex layout can only be properly supported by the Uniscribe or HarfBuzz backends. By default, two backends are enabled for each frame: gdi and either harfbuzz or uniscribe, depending on which one is available (if both are available, only harfbuzz is enabled by default). The harfbuzz and uniscribe backends take priority over gdi when Emacs looks for a suitable font. To override that and use the GDI backend even if Uniscribe is available, invoke Emacs with the -xrm Emacs.fontBackend:gdi command-line argument, or add a Emacs.fontBackend resource with the value gdi in the Registry under either the ‘HKEY_CURRENT_USER\SOFTWARE\GNU\Emacs’ or the ‘HKEY_LOCAL_MACHINE\SOFTWARE\GNU\Emacs’ key (see X Resources). Similarly, to use the Uniscribe backend even if HarfBuzz is available, use -xrm Emacs.fontBackend:uniscribe on the command line that invokes Emacs. You can also request all the 3 backends via the font-backend frame parameter, but be warned that in that case font searches for characters for which no fonts are available on the system will take longer.

Alternatively, you could specify a font backend for a frame via the font-backend frame parameter, using modify-frame-parameters (see Parameter Access in The Emacs Lisp Reference Manual). You can also request specific font backend(s) for all your frames via default-frame-alist and initial-frame-alist (see Frame Parameters). Note that the value of the font-backend parameter should be a list of symbols, as in (uniscribe) or (harfbuzz uniscribe gdi).

Optional font properties supported on MS-Windows are:

weight ¶

Specifies the weight of the font. Special values light, medium, demibold, bold, and black can be specified without weight= (e.g., Courier New-12:bold). Otherwise, the weight should be a numeric value between 100 and 900, or one of the named weights in font-weight-table. If unspecified, a regular font is assumed.

slant ¶

Specifies whether the font is italic. Special values roman, italic and oblique can be specified without slant= (e.g., Courier New-12:italic). Otherwise, the slant should be a numeric value, or one of the named slants in font-slant-table. On Windows, any slant above 150 is treated as italics, and anything below as roman.

family

Specifies the font family, but normally this will be specified at the start of the font name.

pixelsize

Specifies the font size in pixels. This can be used instead of the point size specified after the family name.

adstyle

Specifies additional style information for the font. On MS-Windows, the values mono, sans, serif, script and decorative are recognized. These are most useful as a fallback with the font family left unspecified.

registry ¶

Specifies the character set registry that the font is expected to cover. Most TrueType and OpenType fonts will be Unicode fonts that cover several national character sets, but you can narrow down the selection of fonts to those that support a particular character set by using a specific registry from w32-charset-info-alist here.

spacing

Specifies how the font is spaced. The p spacing specifies a proportional font, and m or c specify a monospaced font.

foundry

Not used on Windows, but for informational purposes and to prevent problems with code that expects it to be set, is set internally to raster for bitmapped fonts, outline for scalable fonts, or unknown if the type cannot be determined as one of those.

script ¶

Specifies a Unicode subrange the font should support.

All the scripts known to Emacs (which generally means all the scripts defined by the latest Unicode Standard) are recognized on MS-Windows. However, GDI fonts support only a subset of the known scripts: greek, hangul, kana, kanbun, bopomofo, tibetan, yi, mongolian, hebrew, arabic, and thai.

antialias ¶

Specifies the antialiasing method. The value none means no antialiasing, standard means use standard antialiasing, subpixel means use subpixel antialiasing (known as Cleartype on Windows), and natural means use subpixel antialiasing with adjusted spacing between letters. If unspecified, the font will use the system default antialiasing.

The method used by Emacs on MS-Windows to look for fonts suitable for displaying a given non-ASCII character might fail for some rare scripts, specifically those added by Unicode relatively recently, even if you have fonts installed on your system that support those scripts. That is because these scripts have no Unicode Subrange Bits (USBs) defined for them in the information used by Emacs on MS-Windows to look for fonts. You can use the w32-find-non-USB-fonts function to overcome these problems. It needs to be run once at the beginning of the Emacs session, and again if you install new fonts. You can add the following line to your init file to have this function run every time you start Emacs:

(w32-find-non-USB-fonts)

Alternatively, you can run this function manually via M-: (see Evaluating Emacs Lisp Expressions) at any time. On a system that has many fonts installed, running w32-find-non-USB-fonts might take a couple of seconds; if you consider that to be too long to be run during startup, and if you install new fonts only rarely, run this function once via M-:, and then assign the value it returns, if non-nil, to the variable w32-non-USB-fonts in your init file. (If the function returns nil, you have no fonts installed that can display characters from the scripts which need this facility.)

The variable w32-use-w32-font-dialog controls the way fonts can be selected via S-mouse-1 (mouse-appearance-menu). If the value is t, the default, Emacs uses the standard Windows font selection dialog. If the value is nil, Emacs instead pops a menu of a fixed set of fonts. The fonts to appear in the menu are determined by w32-fixed-font-alist.

Next: Emacs and MS-DOS, Previous: Specifying Fonts on MS-Windows, Up: Emacs and Microsoft Windows/MS-DOS   [Contents][Index]

I.11 Miscellaneous Windows-specific features ¶

This section describes Windows-specific features that don’t fit anywhere else.

The variable w32-use-visible-system-caret is a flag that determines whether to make the system caret visible. The default when no screen reader software is in use is nil, which means Emacs draws its own cursor to indicate the position of point. A non-nil value means Emacs will indicate point location with the system caret; this facilitates use of screen reader software, and is the default when such software is detected when running Emacs. When this variable is non-nil, other variables affecting the cursor display have no effect.

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

On Windows 10 (version 1809 and higher) and Windows 11, Emacs title bars and scroll bars by default follow the system’s Light or Dark mode, similar to other programs such as Explorer and Command Prompt. To change the color mode, select Personalization from Windows Settings, then Colors->Choose your color (or Choose your default app mode or Choose your mode); then restart Emacs. On Windows 11, you can select separate default modes for Windows and for applications.

If you don’t want Emacs to follow the system’s Dark mode setting, customize the variable w32-follow-system-dark-mode to a nil value; then Emacs will use the default Light mode regardless of system-wide settings. Changing the value of this variable affects only the Emacs frames created after the change, so you should set its value in your init file (see The Emacs Initialization File), either directly or via M-x customize-variable, which lets you save the customized value, see Saving Customizations.

The implementation of display functionality for Windows Console differs from the implementation for other terminal emulators, because historically, Windows required use of an idiosyncractic API. That API limited Windows Console display of Emacs to 16 basic colors. With the introduction of Windows Terminal, Microsoft implemented support for ANSI control sequences, modelled on the VT100 and Xterm, as well as 24-bit RBG color display.

The functions w32-use-virtual-terminal and w32-use-virtual-terminal-p can be used to set and inspect (respectively) an internal variable which determines whether this newer mechanism is used for display, or the older one. The internal variable is automatically set based on your terminal’s capabilities on startup. By default, 24-bit RGB color will be used, but other (8, 16, 256) color spaces may be used, by passing the --color command line argument, or setting the value of the tty-color-mode frame parameter.

(w32-use-virtual-terminal-p) evaluates to t if and only if the internal variable has a non-zero numerical value, and otherwise to nil. If it evaluates to t, ANSI escape sequences are used for color, otherwise, the older mechanism is used. The internal variable can be set by evaluating (w32-use-virtual-terminal x), where x is t or nil: if x is t and the feature is supported by your terminal, it will be enabled. Otherwise, the feature will be disabled.

Previous: Miscellaneous Windows-specific features, Up: Emacs and Microsoft Windows/MS-DOS   [Contents][Index]

I.12 Emacs and MS-DOS ¶

This section briefly describes the peculiarities of using Emacs on MS-DOS. Information about peculiarities common to MS-DOS and Microsoft’s current operating systems Windows is in Emacs and Microsoft Windows/MS-DOS.

If you build Emacs for MS-DOS, the binary will also run on Windows 3.X, Windows NT, Windows 9X/ME, or Windows 2000/XP as a DOS application; all of this chapter applies for all of those systems, if you use an Emacs that was built for MS-DOS.

See Text Files and Binary Files, for information about Emacs’s special handling of text files under MS-DOS (and Windows).

• Keyboard Usage on MS-DOS
• Mouse Usage on MS-DOS
• Display on MS-DOS
• File Names on MS-DOS
• Printing and MS-DOS
• International Support on MS-DOS
• Subprocesses on MS-DOS

;; Make the ENTER key from the numeric keypad act as C-j.
(keymap-set function-key-map "<kp-enter>" "C-j")

;; Treat the mouse like a 2-button mouse.
(msdos-set-mouse-buttons 2)

 '(cursor-type bar width . start)

(setq screen-dimensions-66x80 85)