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1 neysx 1.1 <?xml version='1.0' encoding="UTF-8"?>
2 bennyc 1.10 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/utf-8.xml,v 1.5 2005/02/24 14:57:18 cam Exp $ -->
3 neysx 1.1 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
4    
5     <guide link="/doc/en/utf-8.xml">
6     <title>Using UTF-8 with Gentoo</title>
7    
8     <author title="Author">
9     <mail link="slarti@gentoo.org">Thomas Martin</mail>
10     </author>
11     <author title="Contributor">
12     <mail link="devil@gentoo.org.ua">Alexander Simonov</mail>
13     </author>
14    
15     <abstract>
16     This guide shows you how to set up and use the UTF-8 Unicode character set with
17     your Gentoo Linux system, after explaining the benefits of Unicode and more
18     specifically UTF-8.
19     </abstract>
20    
21     <license />
22    
23 bennyc 1.10 <version>1.5</version>
24     <date>2005-04-23</date>
25 neysx 1.1
26     <chapter>
27     <title>Character Encodings</title>
28     <section>
29     <title>What is a Character Encoding?</title>
30     <body>
31    
32     <p>
33     Computers do not understand text themselves. Instead, every character is
34     represented by a number. Traditionally, each set of numbers used to represent
35     alphabets and characters (known as a coding system, encoding or character set)
36     was limited in size due to limitations in computer hardware.
37     </p>
38    
39     </body>
40     </section>
41     <section>
42     <title>The History of Character Encodings</title>
43     <body>
44    
45     <p>
46     The most common (or at least the most widely accepted) character set is
47     <b>ASCII</b> (American Standard Code for Information Interchange). It is widely
48     held that ASCII is the most successful software standard ever. Modern ASCII
49     was standardised in 1986 (ANSI X3.4, RFC 20, ISO/IEC 646:1991, ECMA-6) by the
50     American National Standards Institute.
51     </p>
52    
53     <p>
54     ASCII is strictly seven-bit, meaning that it uses bit patterns representable
55     with seven binary digits, which provides a range of 0 to 127 in decimal. These
56     include 32 non-visible control characters, most between 0 and 31, with the
57     final control character, DEL or delete at 127. Characters 32 to 126 are
58     visible characters: a space, punctuation marks, Latin letters and numbers.
59     </p>
60    
61     <p>
62     The eighth bit in ASCII was originally used as a parity bit for error checking.
63     If this is not desired, it is left as 0. This means that, with ASCII, each
64     character is represented by a single byte.
65     </p>
66    
67     <p>
68     Although ASCII was enough for communication in modern English, in other
69     European languages that include accented characters, things were not so easy.
70     The ISO 8859 standards were developed to meet these needs. They were backwards
71     compatible with ASCII, but instead of leaving the eighth bit blank, they used
72     it to allow another 127 characters in each encoding. ISO 8859's limitations
73     soon came to light, and there are currently 15 variants of the ISO 8859
74     standard (8859-1 through to 8859-15). Outside of the ASCII-compatible byte
75     range of these character sets, there is often conflict between the letters
76     represented by each byte. To complicate interoperability between character
77     encodings further, Windows-1252 is used in some versions of Microsoft Windows
78     instead for Western European languages. This is a superset of ISO 8859-1,
79     however it is different in several ways. These sets do all retain ASCII
80     compatibility, however.
81     </p>
82    
83     <p>
84     The necessary development of completely different single-byte encodings for
85     non-Latin alphabets, such as EUC (Extended Unix Coding) which is used for
86     Japanese and Korean (and to a lesser extent Chinese) created more confusion,
87     while other operating systems still used different character sets for the same
88     languages, for example, Shift-JIS and ISO-2022-JP. Users wishing to view
89     cyrillic glyphs had to choose between KOI8-R for Russian and Bulgarian or
90     KOI8-U for Ukrainian, as well as all the other cyrillic encodings such as the
91     unsuccessful ISO 8859-5, and the common Windows-1251 set. All of these
92     character sets broke most compatibility with ASCII (although KOI8 encodings
93     place cyrillic characters in Latin order, so in case the eighth bit is
94     stripped, text is still decipherable on an ASCII terminal through case-reversed
95     transliteration.)
96     </p>
97    
98     <p>
99     This has led to confusion, and also to an almost total inability for
100     multilingual communication, especially across different alphabets. Enter
101     Unicode.
102     </p>
103    
104     </body>
105     </section>
106     <section>
107     <title>What is Unicode?</title>
108     <body>
109    
110     <p>
111 bennyc 1.10 Unicode throws away the traditional single-byte limit of character sets, and
112     even with two bytes per-character this allows a maximum 65,536 characters.
113     Although this number is extremely high when compared to seven-bit and eight-bit
114     encodings, it is still not enough for a character set designed to be used for
115     symbols and scripts used only by scholars, and symbols that are only used in
116     mathematics and other specialised fields.
117 neysx 1.1 </p>
118    
119     <p>
120     Unicode has been mapped in many different ways, but the two most common are
121     <b>UTF</b> (Unicode Transformation Format) and <b>UCS</b> (Universal Character
122     Set). A number after UTF indicates the number of bits in one unit, while the
123     number after UCS indicates the number of bytes. UTF-8 has become the most
124     widespread means for the interchange of Unicode text as a result of its
125     eight-bit clean nature, and it is the subject of this document.
126     </p>
127    
128     </body>
129     </section>
130     <section>
131     <title>UTF-8</title>
132     <body>
133    
134     <p>
135     UTF-8 is a variable-length character encoding, which in this instance means
136     that it uses 1 to 4 bytes per symbol. So, the first UTF-8 byte is used for
137     encoding ASCII, giving the character set full backwards compatibility with
138     ASCII. UTF-8 means that ASCII and Latin characters are interchangeable with
139     little increase in the size of the data, because only the first bit is used.
140     Users of Eastern alphabets such as Japanese, who have been assigned a higher
141     byte range are unhappy, as this results in as much as a 50% redundancy in their
142     data.
143     </p>
144    
145     </body>
146     </section>
147     <section>
148     <title>What UTF-8 Can Do for You</title>
149     <body>
150    
151     <p>
152     UTF-8 allows you to work in a standards-compliant and internationally accepted
153 bennyc 1.10 multilingual environment, with a comparitively low data redundancy. UTF-8 is
154 neysx 1.1 the preferred way for transmitting non-ASCII characters over the Internet,
155     through Email, IRC or almost any other medium. Despite this, many people regard
156     UTF-8 in online communication as abusive. It is always best to be aware of the
157     attitude towards UTF-8 in a specific channel, mailing list or Usenet group
158     before using <e>non-ASCII</e> UTF-8.
159     </p>
160    
161     </body>
162     </section>
163     </chapter>
164    
165     <chapter>
166     <title>Setting up UTF-8 with Gentoo Linux</title>
167     <section>
168     <title>Finding or Creating UTF-8 Locales</title>
169     <body>
170    
171     <p>
172     Now that you understand the principles behind Unicode, you're ready to start
173     using UTF-8 with your system.
174     </p>
175    
176     <p>
177     The preliminary requirement for UTF-8 is to have a version of glibc installed
178     that has national language support. The recommend means to do this is the
179     <path>/etc/locales.build</path> file in combination with the <c>userlocales</c>
180     USE flag. It is beyond the scope of this document to explain the usage of this
181     file though, luckily, the usage of this file is well documented in the comments
182     within it. It is also explained in the <uri
183     link="/doc/en/guide-localization.xml#doc_chap3_sect3"> Gentoo Localisation
184     Guide</uri>.
185     </p>
186    
187     <p>
188     Next, we'll need to decide whether a UTF-8 locale is already available for our
189     language, or whether we need to create one.
190     </p>
191    
192     <pre caption="Checking for an existing UTF-8 locale">
193     <comment>(Replace "en_GB" with your desired locale setting)</comment>
194     # <i>locale -a | grep 'en_GB'</i>
195     en_GB
196     en_GB.utf8
197     </pre>
198    
199     <p>
200     From the output of this command line, we need to take the result with a suffix
201     similar to <c>.utf8</c>. If there is no result with a suffix similar to
202     <c>.utf8</c>, we need to create a UTF-8 compatible locale.
203     </p>
204    
205     <note>
206     Only execute the following code listing if you do not have a UTF-8 locale
207     available for your language.
208     </note>
209    
210     <pre caption="Creating a UTF-8 locale">
211     <comment>(Replace "en_GB" with your desired locale setting)</comment>
212     # <i>localedef -i en_GB -f UTF-8 en_GB.utf8</i>
213     </pre>
214    
215     </body>
216     </section>
217     <section>
218     <title>Setting the Locale</title>
219     <body>
220    
221     <p>
222 bennyc 1.10 There are two environment variables that need to be set in order to use
223     our new UTF-8 locales: <c>LANG</c> and <c>LC_ALL</c>. There are also
224     many different ways to set them; some people prefer to only have a UTF-8
225     environment for a specific user, in which case they set them in their
226     <path>~/.profile</path> or <path>~/.bashrc</path>. Others prefer to set the
227     locale globally. One specific circumstance where the author particularly
228     recommends doing this is when <path>/etc/init.d/xdm</path> is in use, because
229     this init script starts the display manager and desktop before any of the
230     aforementioned shell startup files are sourced, and so before any of the
231     variables are in the environment.
232 neysx 1.1 </p>
233    
234 bennyc 1.10 <p>
235     Setting the locale globally should be done using
236     <path>/etc/env.d/02local</path>. The file should look something like the
237     following:
238     </p>
239    
240     <pre caption="Demonstration /etc/env.d/02locale">
241     <comment>(As always, change "en_GB.UTF-8" to your locale)</comment>
242     LC_ALL="en_GB.UTF-8"
243     LOCALE="en_GB.UTF-8"
244     </pre>
245    
246     <p>
247     Next, the environment must be updated with the change.
248     </p>
249 neysx 1.1
250 bennyc 1.10 <pre caption="Updating the environment">
251     # <i>env-update</i>
252     >>> Regenerating /etc/ld.so.cache...
253     * Caching service dependencies ...
254     # <i>source /etc/profile</i>
255 neysx 1.1 </pre>
256    
257 bennyc 1.10 <p>
258     Now, run <c>locale</c> with no arguments to see if we have the correct
259     variables in our environment:
260     </p>
261    
262     <pre caption="Checking if our new locale is in the environment">
263     # <i>locale</i>
264     LANG=en_GB.UTF-8
265     LC_CTYPE="en_GB.UTF-8"
266     LC_NUMERIC="en_GB.UTF-8"
267     LC_TIME="en_GB.UTF-8"
268     LC_COLLATE="en_GB.UTF-8"
269     LC_MONETARY="en_GB.UTF-8"
270     LC_MESSAGES="en_GB.UTF-8"
271     LC_PAPER="en_GB.UTF-8"
272     LC_NAME="en_GB.UTF-8"
273     LC_ADDRESS="en_GB.UTF-8"
274     LC_TELEPHONE="en_GB.UTF-8"
275     LC_MEASUREMENT="en_GB.UTF-8"
276     LC_IDENTIFICATION="en_GB.UTF-8"
277     LC_ALL=en_GB.UTF-8
278 neysx 1.1 </pre>
279    
280     <p>
281 bennyc 1.10 That is all. You are now using UTF-8 locales, and the next hurdle is the
282     configuration of the applications you use from day to day.
283 neysx 1.1 </p>
284    
285     </body>
286     </section>
287     </chapter>
288    
289     <chapter>
290     <title>Application Support</title>
291     <section>
292     <body>
293    
294     <p>
295     When Unicode first started gaining momentum in the software world, multibyte
296     character sets were not well suited to languages like C, in which many of the
297     day-to-day programs people use are written. Even today, some programs are not
298     able to handle UTF-8 properly. Fortunately, most are!
299     </p>
300    
301     </body>
302     </section>
303     <section>
304     <title>Filenames, NTFS, and FAT</title>
305     <body>
306    
307     <p>
308     There are several NLS options in the Linux kernel configuration menu, but it is
309     important to not become confused! For the most part, the only thing you need to
310     do is to build UTF-8 NLS support into your kernel, and change the default NLS
311     option to utf8.
312     </p>
313    
314     <pre caption="Kernel configuration steps for UTF-8 NLS">
315     File Systems --&gt;
316     Native Language Support --&gt;
317     (utf8) Default NLS Option
318     &lt;*&gt; NLS UTF8
319     <comment>(Also &lt;*&gt; other character sets that are in use in
320     your FAT filesystems or Joilet CD-ROMs.)</comment>
321     </pre>
322    
323     <p>
324     If you plan on mounting NTFS partitions, you may need to specify an <c>nls=</c>
325     option with mount. For more information, see <c>man mount</c>.
326     </p>
327    
328     <p>
329     For changing the encoding of filenames, <c>app-text/convmv</c> can be used.
330     </p>
331    
332     <pre caption="Example usage of convmv">
333     # <i>emerge --ask app-text/convmv</i>
334     # <i>convmv -f current-encoding -t utf-8 filename</i>
335     </pre>
336    
337     <p>
338     For changing the <e>contents</e> of files, use the <c>iconv</c> utility,
339     bundled with <c>glibc</c>:
340     </p>
341    
342     <pre caption="Example usage of iconv">
343     <comment>(substitute iso-8859-1 with the charset you are converting from)</comment>
344     <comment>(Check the output is sane)</comment>
345     # <i>iconv -f iso-8859-1 -t utf-8 filename</i>
346     <comment>(Convert a file, you must create another file)</comment>
347     # <i>iconv -f iso-8859-1 -t utf-8 filename > newfile</i>
348     </pre>
349    
350     <p>
351     <c>app-text/recode</c> can also be used for this purpose.
352     </p>
353    
354     </body>
355     </section>
356     <section>
357     <title>The System Console</title>
358     <body>
359    
360     <impo>
361     You need >=sys-apps/baselayout-1.11.9 for Unicode on the console.
362     </impo>
363    
364     <p>
365     To enable UTF-8 on the console, you should edit <path>/etc/rc.conf</path> and
366     set <c>UNICODE="yes"</c>, and also read the comments in that file -- it is
367     important to have a font that has a good range of characters if you plan on
368     making the most of Unicode.
369     </p>
370    
371     <p>
372     The <c>KEYMAP</c> variable, set in <path>/etc/conf.d/keymaps</path>, should
373     have a Unicode keymap specified. To do this, simply prepend the keymap already
374     specified there with -u.
375     </p>
376    
377     <pre caption="Example /etc/conf.d/keymaps snippet">
378     <comment>(Change "uk" to your local layout)</comment>
379 bennyc 1.10 KEYMAP="uk"
380 neysx 1.1 </pre>
381    
382     </body>
383     </section>
384     <section>
385     <title>Ncurses and Slang</title>
386     <body>
387    
388     <note>
389     Ignore any mention of Slang in this section if you do not have it installed or
390     do not use it.
391     </note>
392    
393     <p>
394     It is wise to add <c>unicode</c> to your global USE flags in
395     <path>/etc/make.conf</path>, and then to remerge <c>sys-libs/ncurses</c> and
396     also <c>sys-libs/slang</c> if appropriate:
397     </p>
398    
399     <pre caption="Emerging ncurses and slang">
400     <comment>(We avoid putting these libraries in our world file with --oneshot)</comment>
401     # <i>emerge --oneshot --verbose --ask sys-libs/ncurses sys-libs/slang</i>
402     </pre>
403    
404     <p>
405     We also need to rebuild packages that link to these, now the USE changes have
406 bennyc 1.10 been applied.
407 neysx 1.1 </p>
408    
409     <pre caption="Rebuilding of programs that link to ncurses or slang">
410     # <i>revdep-rebuild --soname libncurses.so.5</i>
411     # <i>revdep-rebuild --soname libslang.so.1</i>
412     </pre>
413    
414     </body>
415     </section>
416     <section>
417     <title>KDE, GNOME and Xfce</title>
418     <body>
419    
420     <p>
421     All of the major desktop environments have full Unicode support, and will
422     require no further setup than what has already been covered in this guide. This
423     is because the underlying graphical toolkits (Qt or GTK+2) are UTF-8 aware.
424     Subsequently, all applications running on top of these toolkits should be
425     UTF-8-aware out of the box.
426     </p>
427    
428     <p>
429     The exceptions to this rule come in Xlib and GTK+1. GTK+1 requires a
430     iso-10646-1 FontSpec in the ~/.gtkrc, for example
431     <c>-misc-fixed-*-*-*-*-*-*-*-*-*-*-iso10646-1</c>. Also, applications using
432     Xlib or Xaw will need to be given a similar FontSpec, otherwise they will not
433     work.
434     </p>
435    
436     <note>
437     If you have a version of the gnome1 control center around, use that instead.
438     Pick any iso10646-1 font from there.
439     </note>
440    
441     <pre caption="Example ~/.gtkrc (for GTK+1) that defines a Unicode compatible font">
442     style "user-font"
443     {
444     fontset="-misc-fixed-*-*-*-*-*-*-*-*-*-*-iso10646-1"
445     }
446     widget_class "*" style "user-font"
447     </pre>
448    
449     <p>
450     If an application has support for both a Qt and GTK+2 GUI, the GTK+2 GUI will
451     generally give better results with Unicode.
452     </p>
453    
454     </body>
455     </section>
456     <section>
457     <title>X11 and Fonts</title>
458     <body>
459    
460     <p>
461     TrueType fonts have support for Unicode, and most of the fonts that ship with
462     Xorg have impressive character support, although, obviously, not every single
463     glyph available in Unicode has been created for that font. To build fonts
464     (including the Bitstream Vera set) with support for East Asian letters with X,
465     make sure you have the <c>cjk</c> USE flag set. Many other applications utilise
466     this flag, so it may be worthwhile to add it as a permanent USE flag.
467     </p>
468    
469     <p>
470     Also, several font packages in Portage are Unicode aware.
471     </p>
472    
473     <pre caption="Optional: Install some more Unicode-aware fonts">
474     # <i>emerge terminus-font intlfonts freefonts cronyx-fonts corefonts</i>
475     </pre>
476    
477     </body>
478     </section>
479     <section>
480     <title>Window Managers and Terminal Emulators</title>
481     <body>
482    
483     <p>
484 bennyc 1.10 Window managers, even those not built on GTK or Qt, generally have very
485     good Unicode support, as they often use the Xft library for handling
486     fonts. If your window manager does not use Xft for fonts, you can still
487     use the FontSpec mentioned in the previous section as a Unicode font.
488 neysx 1.1 </p>
489    
490     <p>
491     Terminal emulators that use Xft and support Unicode are harder to come by.
492     Aside from Konsole and gnome-terminal, the best options in Portage are
493     <c>x11-terms/rxvt-unicode</c>, <c>xfce-extra/terminal</c>,
494 cam 1.5 <c>gnustep-apps/terminal</c>, <c>x11-terms/mlterm</c>, <c>x11-terms/mrxvt</c> or
495 neysx 1.1 plain <c>x11-terms/xterm</c> when built with the <c>unicode</c> USE flag and
496     invoked as <c>uxterm</c>. <c>app-misc/screen</c> supports UTF-8 too, when
497 bennyc 1.10 invoked as <c>screen -U</c> or the following is put into the
498 neysx 1.1 <path>~/.screenrc</path>:
499     </p>
500    
501     <pre caption="~/.screenrc for UTF-8">
502     defutf8 on
503     </pre>
504    
505     </body>
506     </section>
507     <section>
508     <title>Vim, Emacs, Xemacs and Nano</title>
509     <body>
510    
511     <p>
512     Vim, Emacs and Xemacs provide full UTF-8 support, and also have builtin
513     detection of UTF-8 files. For further information in Vim, use <c>:help
514     mbyte.txt</c>.
515     </p>
516    
517     <p>
518     Nano currently does not provide support for UTF-8, although it has been planned
519     for a long time. With luck, this will change in future. At the time of writing,
520     UTF-8 support is in Nano's CVS, and should be included in the next release.
521     </p>
522    
523     </body>
524     </section>
525     <section>
526     <title>Shells</title>
527     <body>
528    
529     <p>
530     Currently, <c>bash</c> provides full Unicode support through the GNU readline
531     library. Z Shell users are in a somewhat worse position -- no parts of the
532     shell have Unicode support, although there is a concerted effort to add
533     multibyte character set support underway at the moment.
534     </p>
535    
536     <p>
537     The C shell, <c>tcsh</c> and <c>ksh</c> do not provide UTF-8 support at all.
538     </p>
539    
540 bennyc 1.10 <note>
541     Although not strictly related to shells, many of the GNU text-processing
542     programs in your system (<c>tr</c>, <c>grep</c>, etc.) are much slower
543     when processing Unicode. Nonetheless, the difference is not at all
544     noticeable in nearly every case, but if you are ever hit by these bugs
545     then at least you will know what is causing them. Perl also tends to be
546     slower when operating on multibyte characters. The author knows of one
547     other gotcha: <c>tr</c> will not convert three-byte UTF-8 characters to
548     two-byte UTF-8 characters.
549     </note>
550    
551 neysx 1.1 </body>
552     </section>
553     <section>
554     <title>Irssi</title>
555     <body>
556    
557     <p>
558 cam 1.5 Since 0.8.10, Irssi has complete UTF-8 support, although it does require a user
559     to set an option.
560 neysx 1.1 </p>
561    
562     <pre caption="Enabling UTF-8 in Irssi">
563     /set term_charset UTF-8
564     </pre>
565    
566     <p>
567     For channels where non-ASCII characters are often exchanged in non-UTF-8
568     charsets, the <c>/recode</c> command may be used to convert the characters.
569     Type <c>/help recode</c> for more information.
570     </p>
571    
572     </body>
573     </section>
574     <section>
575     <title>Mutt</title>
576     <body>
577    
578     <p>
579     The Mutt mail user agent has very good Unicode support. To use UTF-8 with Mutt,
580     put the following in your <path>~/.muttrc</path>:
581     </p>
582    
583     <pre caption="~/.muttrc for UTF-8">
584     set send_charset="utf8" <comment>(outgoing character set)</comment>
585     set charset="utf8" <comment>(display character set)</comment>
586     </pre>
587    
588     <note>
589     You may still see '?' in mail you read with Mutt. This is a result of people
590 bennyc 1.10 using Latin (ISO 8859) or another charset for email transmission. It is best to
591     tell them to use UTF-8 for mail, and point them to the IETF RFC 2277 (see
592     References at the end of this document). Also note that in some lists,
593     subscribers may not like UTF-8. Be sure that the group or person you are
594     communicating with does not mind UTF-8.
595 neysx 1.1 </note>
596    
597     <p>
598     Further information is available from the <uri
599     link="http://wiki.mutt.org/index.cgi?MuttFaq/Charset"> Mutt WikiWiki</uri>.
600     </p>
601    
602     </body>
603     </section>
604     <section>
605     <title>Testing it all out</title>
606     <body>
607    
608     <p>
609     There are numerous UTF-8 test websites around. <c>net-www/w3m</c>,
610     <c>net-www/links</c>, <c>net-www/elinks</c>, <c>net-www/lynx</c> and all
611 cam 1.3 Mozilla based browsers (including Firefox) support UTF-8. Konqueror and Opera
612     have full UTF-8 support too.
613 neysx 1.1 </p>
614    
615     <p>
616     When using one of the text-only web browsers, make absolutely sure you are
617     using a Unicode-aware terminal.
618     </p>
619    
620     <p>
621     If you see certain characters displayed as boxes with letters or numbers
622     inside, this means that your font does not have a character for the symbol or
623     glyph that the UTF-8 wants. Instead, it displays a box with the hex code of the
624     UTF-8 symbol.
625     </p>
626    
627     <ul>
628     <li>
629     <uri link="http://www.w3.org/2001/06/utf-8-test/UTF-8-demo.html">A W3C
630     UTF-8 Test Page</uri>
631     </li>
632     <li>
633     <uri link="http://titus.uni-frankfurt.de/indexe.htm?/unicode/unitest.htm">
634     A UTF-8 test page provided by the University of Frankfurt</uri>
635     </li>
636     </ul>
637    
638     </body>
639     </section>
640     <section>
641     <title>Input Methods</title>
642     <body>
643    
644     <p>
645     <e>Dead keys</e> may be used to input characters in X that are not included on
646     your keyboard. These work by pressing your right Alt key (or in some countries,
647     AltGr) and an optional key from the non-alphabetical section of the keyboard to
648     the left of the return key at once, releasing them, and then pressing a letter.
649     The dead key should modify it. Input can be further modified by using the Shift
650     key at the same time as pressing the AltGr and modifier.
651     </p>
652    
653     <p>
654     To enable dead keys in X, you need a layout that supports it. Most European
655     layouts already have dead keys with the default variant. However, this is not
656     true of North American layouts. Although there is a degree of inconsistency
657     between layouts, the easiest solution seems to be to use a layout in the form
658     "en_US" rather than "us", for example. The layout is set in
659     <path>/etc/X11/xorg.conf</path> like so:
660     </p>
661    
662     <pre caption="/etc/X11/xorg.conf snippet">
663     Section "InputDevice"
664     Identifier "Keyboard0"
665     Driver "kbd"
666     Option "XkbLayout" "en_US" <comment># Rather than just "us"</comment>
667     <comment>(Other Xkb options here)</comment>
668     EndSection
669     </pre>
670    
671     <note>
672     The preceding change only needs to be applied if you are using a North American
673     layout, or another layout where dead keys do not seem to be working. European
674     users should have working dead keys as is.
675     </note>
676    
677     <p>
678 bennyc 1.10 This change will come into effect when the X server is restarted. To apply the
679 neysx 1.1 change now, use the <c>setxkbmap</c> tool, for example, <c>setxkbmap en_US</c>.
680     </p>
681    
682     <p>
683     It is probably easiest to describe dead keys with examples. Although the
684 bennyc 1.10 results are layout dependent, the concepts should remain the same regardless of
685 neysx 1.1 locale. The examples contain UTF-8, so to view them you need to either tell
686     your browser to view the page as UTF-8, or have a UTF-8 locale already
687     configured.
688     </p>
689    
690     <p>
691     When I press AltGr and [ at once, release them, and then press a, 'ä' is
692 bennyc 1.10 produced. When I press AltGr and [ at once, and then press e, 'ë' is
693     produced. When I press AltGr and ; at once, release them, and press a,
694     'á' is produced, and when I press AltGr and ; at once, release them, and
695     then press e, 'é' is produced.
696 neysx 1.1 </p>
697    
698     <p>
699     By pressing AltGr, Shift and [ at once, releasing them, and then pressing a, a
700     Scandinavian 'å' is produced. Similarly, when I press AltGr, Shift and [ at
701     once, release <e>only</e> the [, and then press it again, '˚' is produced.
702     Although it looks like one, this (U+02DA) is not the same as a degree symbol
703     (U+00B0). This works for other accents produced by dead keys — AltGr and [,
704     releasing only the [, then pressing it again makes '¨'.
705     </p>
706    
707     <p>
708     AltGr can be used with alphabetical keys alone. For example, AltGr and m, a
709 bennyc 1.10 Greek lower-case letter mu is produced: 'µ'. AltGr and s produce a
710     Schauffer's s: 'ß'. As many European users would expect (because it is
711     marked on their keyboard), AltGr and 4 produces a Euro sign, '€'.
712 neysx 1.1 </p>
713    
714     </body>
715     </section>
716     <section>
717     <title>Resources</title>
718     <body>
719    
720     <ul>
721     <li>
722     <uri link="http://www.wikipedia.com/wiki/Unicode">The Wikipedia entry for
723     Unicode</uri>
724     </li>
725     <li>
726     <uri link="http://www.wikipedia.com/wiki/UTF-8">The Wikipedia entry for
727     UTF-8</uri>
728     </li>
729     <li><uri link="http://www.unicode.org">Unicode.org</uri></li>
730     <li><uri link="http://www.utf-8.com">UTF-8.com</uri></li>
731     <li><uri link="http://www.ietf.org/rfc/rfc3629.txt">RFC 3629</uri></li>
732     <li><uri link="http://www.ietf.org/rfc/rfc2277.txt">RFC 2277</uri></li>
733     </ul>
734    
735     </body>
736     </section>
737     </chapter>
738     </guide>

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