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The Unicode HOWTO
Bruno Haible, <haible@clisp.cons.org>
v1.0, 23 January 2001
This document describes how to change your Linux system so it uses
UTF-8 as text encoding. - This is work in progress. Any tips, patches,
pointers, URLs are very welcome.
______________________________________________________________________
Table of Contents
1. Introduction
1.1 Why Unicode?
1.2 Unicode encodings
1.2.1 Footnotes for C/C++ developers
1.3 Related resources
2. Display setup
2.1 Linux console
2.2 X11 Foreign fonts
2.3 X11 Unicode fonts
2.4 Unicode xterm
2.5 TrueType fonts
2.6 Miscellaneous
3. Locale setup
3.1 Files & the kernel
3.2 Upgrading the C library
3.3 General data conversion
3.4 Locale environment variables
3.5 Creating the locale support files
4. Specific applications
4.1 Shells
4.1.1 bash
4.2 Networking
4.2.1 telnet
4.2.2 kermit
4.3 Browsers
4.3.1 Netscape
4.3.2 Mozilla
4.3.3 Amaya
4.3.4 lynx
4.3.5 w3m
4.3.6 Test pages
4.4 Editors
4.4.1 yudit
4.4.1.1 yudit-1.5
4.4.1.2 yudit-2.1
4.4.1.3 Fonts for yudit
4.4.2 vim
4.4.3 cooledit
4.4.4 emacs
4.4.5 xemacs
4.4.6 nedit
4.4.7 xedit
4.4.8 axe
4.4.9 pico
4.4.10 mined98
4.4.11 qemacs
4.5 Mailers
4.5.1 pine
4.5.2 kmail
4.5.3 Netscape Communicator
4.5.4 emacs (rmail, vm)
4.5.5 mutt
4.5.6 exmh
4.6 Text processing
4.6.1 groff
4.6.2 TeX
4.7 Databases
4.7.1 PostgreSQL
4.7.2 Interbase
4.8 Other text-mode applications
4.8.1 less
4.8.2 lv
4.8.3 expand
4.8.4 col, colcrt, colrm, column, rev, ul
4.8.5 figlet
4.8.6 Base utilities
4.9 Other X11 applications
5. Printing
5.1 Printing using TrueType fonts
5.1.1 uniprint
5.1.2 wprint
5.1.3 Comparison
5.2 Printing using fixed-size fonts
5.2.1 txtbdf2ps
5.3 The classical approach
5.3.1 TeX, Omega
5.3.2 DocBook
5.3.3 groff -Tps
5.4 No luck with...
5.4.1 Netscape's "Print..."
5.4.2 Mozilla's "Print..."
5.4.3 html2ps
5.4.4 a2ps
5.4.5 enscript
6. Making your programs Unicode aware
6.1 C/C++
6.1.1 For normal text handling
6.1.1.1 Portability notes
6.1.1.2 The libutf8 library
6.1.1.3 The Plan9 way
6.1.2 For graphical user interface
6.1.3 For advanced text handling
6.1.4 For conversion
6.1.4.1 iconv
6.1.4.2 librecode
6.1.4.3 ICU
6.1.5 Other approaches
6.2 Java
6.3 Lisp
6.4 Ada95
6.5 Python
6.6 JavaScript/ECMAscript
6.7 Tcl
6.8 Perl
6.9 Related reading
7. Other sources of information
7.1 Mailing lists
7.1.1 linux-utf8
7.1.2 li18nux
7.1.3 unicode
7.1.4 X11 internationalization
7.1.5 X11 fonts
______________________________________________________________________
1. Introduction
1.1. Why Unicode?
People in different countries use different characters to represent
the words of their native languages. Nowadays most applications,
including email systems and web browsers, are 8-bit clean, i.e. they
can operate on and display text correctly provided that it is
represented in an 8-bit character set, like ISO-8859-1.
There are far more than 256 characters in the world - think of
cyrillic, hebrew, arabic, chinese, japanese, korean and thai -, and
new characters are being invented now and then. The problems that come
up for users are:
<20> It is impossible to store text with characters from different
character sets in the same document. For example, I can cite
russian papers in a German or French publication if I use TeX, xdvi
and PostScript, but I cannot do it in plain text.
<20> As long as every document has its own character set, and
recognition of the character set is not automatic, manual user
intervention is inevitable. For example, in order to view the
homepage of the XTeamLinux distribution
http://www.xteamlinux.com.cn/ I had to tell Netscape that the web
page is coded in GB2312.
<20> New symbols like the Euro are being invented. ISO has issued a new
standard ISO-8859-15, which is mostly like ISO-8859-1 except that
it removes some rarely used characters (the old currency sign) and
replaced it with the Euro sign. If users adopt this standard, they
have documents in different character sets on their disk, and they
start having to think about it daily. But computers should make
things simpler, not more complicated.
The solution of this problem is the adoption of a world-wide usable
character set. This character set is Unicode http://www.unicode.org/.
For more info about Unicode, do `man 7 unicode' (manpage contained in
the man-pages-1.20 package).
1.2. Unicode encodings
This reduces the user's problem of dealing with character sets to a
technical problem: How to transport Unicode characters using the 8-bit
bytes? 8-bit units are the smallest addressing units of most
computers and also the unit used by TCP/IP network connections. The
use of 1 byte to represent 1 character is, however, an accident of
history, caused by the fact that computer development started in
Europe and the U.S. where 96 characters were found to be sufficient
for a long time.
There are basically four ways to encode Unicode characters in bytes:
UTF-8
128 characters are encoded using 1 byte (the ASCII characters).
1920 characters are encoded using 2 bytes (Roman, Greek,
Cyrillic, Coptic, Armenian, Hebrew, Arabic characters). 63488
characters are encoded using 3 bytes (Chinese and Japanese among
others). The other 2147418112 characters (not assigned yet) can
be encoded using 4, 5 or 6 characters. For more info about
UTF-8, do `man 7 utf-8' (manpage contained in the man-pages-1.20
package).
UCS-2
Every character is represented as two bytes. This encoding can
only represent the first 65536 Unicode characters.
UTF-16
This is an extension of UCS-2 which can represent 1112064
Unicode characters. The first 65536 Unicode characters are
represented as two bytes, the other ones as four bytes.
UCS-4
Every character is represented as four bytes.
The space requirements for encoding a text, compared to encodings
currently in use (8 bit per character for European languages, more for
Chinese/Japanese/Korean), is as follows. This has an influence on disk
storage space and network download speed (when no form of compression
is used).
UTF-8
No change for US ASCII, just a few percent more for ISO-8859-1,
50% more for Chinese/Japanese/Korean, 100% more for Greek and
Cyrillic.
UCS-2 and UTF-16
No change for Chinese/Japanese/Korean. 100% more for US ASCII
and ISO-8859-1, Greek and Cyrillic.
UCS-4
100% more for Chinese/Japanese/Korean. 300% more for US ASCII
and ISO-8859-1, Greek and Cyrillic.
Given the penalty for US and European documents caused by UCS-2,
UTF-16, and UCS-4, it seems unlikely that these encodings have a
potential for wide-scale use. The Microsoft Win32 API supports the
UCS-2 encoding since 1995 (at least), yet this encoding has not been
widely adopted for documents - SJIS remains prevalent in Japan.
UTF-8 on the other hand has the potential for wide-scale use, since it
doesn't penalize US and European users, and since many text processing
programs don't need to be changed for UTF-8 support.
In the following, we will describe how to change your Linux system so
it uses UTF-8 as text encoding.
1.2.1. Footnotes for C/C++ developers
The Microsoft Win32 approach makes it easy for developers to produce
Unicode versions of their programs: You "#define UNICODE" at the top
of your program and then change many occurrences of `char' to `TCHAR',
until your program compiles without warnings. The problem with it is
that you end up with two versions of your program: one which
understands UCS-2 text but no 8-bit encodings, and one which
understands only old 8-bit encodings.
Moreover, there is an endianness issue with UCS-2 and UCS-4. The IANA
character set registry http://www.isi.edu/in-
notes/iana/assignments/character-sets says about ISO-10646-UCS-2:
"this needs to specify network byte order: the standard does not
specify". Network byte order is big endian. And RFC 2152 is even
clearer: "ISO/IEC 10646-1:1993(E) specifies that when characters the
UCS-2 form are serialized as octets, that the most significant octet
appear first." Whereas Microsoft, in its C/C++ development tools,
recommends to use machine-dependent endianness (i.e. little endian on
ix86 processors) and either a byte-order mark at the beginning of the
document, or some statistical heuristics(!).
The UTF-8 approach on the other hand keeps `char*' as the standard C
string type. As a result, your program will handle US ASCII text,
independently of any environment variables, and will handle both
ISO-8859-1 and UTF-8 encoded text provided the LANG environment
variable is set accordingly.
1.3. Related resources
Markus Kuhn's very up-to-date resource list:
<20> http://www.cl.cam.ac.uk/~mgk25/unicode.html
<20> http://www.cl.cam.ac.uk/~mgk25/ucs-fonts.html
Roman Czyborra's overview of Unicode, UTF-8 and UTF-8 aware programs:
http://czyborra.com/utf/#UTF-8
Some example UTF-8 files:
<20> In Markus Kuhn's ucs-fonts package: quickbrown.txt, UTF-8-test.txt,
UTF-8-demo.txt.
<20> http://www.columbia.edu/kermit/utf8.html
<20> ftp://ftp.cs.su.oz.au/gary/x-utf8.html
<20> The file iso10646 in the Kosta Kostis' trans-1.1.1 package
ftp://ftp.nid.ru/pub/os/unix/misc/trans111.tar.gz
<20> ftp://ftp.dante.de/pub/tex/info/lwc/apc/utf8.html
<20> http://www.cogsci.ed.ac.uk/~richard/unicode-sample.html
2. Display setup
We assume you have already adapted your Linux console and X11
configuration to your keyboard and locale. This is explained in the
Danish/International HOWTO, and in the other national HOWTOs: Finnish,
French, German, Italian, Polish, Slovenian, Spanish, Cyrillic, Hebrew,
Chinese, Thai, Esperanto. But please do not follow the advice given in
the Thai HOWTO, to pretend you were using ISO-8859-1 characters
(U0000..U00FF) when what you are typing are actually Thai characters
(U0E01..U0E5B). Doing so will only cause problems when you switch to
Unicode.
2.1. Linux console
I'm not talking much about the Linux console here, because on those
machines on which I don't have xdm running, I use it only to type my
login name, my password, and "xinit".
Anyway, the kbd-0.99 package
ftp://sunsite.unc.edu/pub/Linux/system/keyboards/kbd-0.99.tar.gz and a
heavily extended version, the console-tools-0.2.3 package
ftp://sunsite.unc.edu/pub/Linux/system/keyboards/console-
tools-0.2.3.tar.gz contains in the kbd-0.99/src/ (or console-
tools-0.2.3/screenfonttools/) directory two programs: `unicode_start'
and `unicode_stop'. When you call `unicode_start', the console's
screen output is interpreted as UTF-8. Also, the keyboard is put into
Unicode mode (see "man kbd_mode"). In this mode, Unicode characters
typed as Alt-x1 ... Alt-xn (where x1,...,xn are digits on the numeric
keypad) will be emitted in UTF-8. If your keyboard or, more precisely,
your normal keymap has non-ASCII letter keys (like the German Umlaute)
which you would like to be CapsLockable, you need to apply the kernel
patch linux-2.2.9-keyboard.diff or linux-2.3.12-keyboard.diff.
You will want to use display characters from different scripts on the
same screen. For this, you need a Unicode console font. The
ftp://sunsite.unc.edu/pub/Linux/system/keyboards/kbd-0.99.tar.gz and
ftp://sunsite.unc.edu/pub/Linux/system/keyboards/console-
data-1999.08.29.tar.gz packages contain a font
(LatArCyrHeb-{08,14,16,19}.psf) which covers Latin, Cyrillic, Hebrew,
Arabic scripts. It covers ISO 8859 parts 1,2,3,4,5,6,8,9,10 all at
once. To install it, copy it to /usr/lib/kbd/consolefonts/ and execute
"/usr/bin/setfont /usr/lib/kbd/consolefonts/LatArCyrHeb-14.psf".
A more flexible approach is given by Dmitry Yu. Bolkhovityanov
<D.Yu.Bolkhovityanov@inp.nsk.su> in
http://www.inp.nsk.su/~bolkhov/files/fonts/univga/index.html and
http://www.inp.nsk.su/~bolkhov/files/fonts/univga/uni-vga.tgz. To
work around the constraint that a VGA font can only cover 512
characters simultaneously, he provides a rich Unicode font (2279
characters, covering Latin, Greek, Cyrillic, Hebrew, Armenian, IPA,
math symbols, arrows, and more) in the typical 8x16 size and a script
which permits to extract any 512 characters as a console font.
If you want cut&paste to work with UTF-8 consoles, you need the patch
linux-2.3.12-console.diff from Edmund Thomas Grimley Evans and
Stanislav Voronyi.
In April 2000, Edmund Thomas Grimley Evans <edmundo@rano.org> has
implemented an UTF-8 console terminal emulator. It uses Unicode fonts
and relies on the Linux frame buffer device.
2.2. X11 Foreign fonts
Don't hesitate to install Cyrillic, Chinese, Japanese etc. fonts. Even
if they are not Unicode fonts, they will help in displaying Unicode
documents: at least Netscape Communicator 4 and Java will make use of
foreign fonts when available.
The following programs are useful when installing fonts:
<20> "mkfontdir directory" prepares a font directory for use by the X
server, needs to be executed after installing fonts in a directory.
<20> "xset -q | sed -e '1,/^Font Path:/d' | sed -e '2,$d' -e 's/^ //'"
displays the X server's current font path.
<20> "xset fp+ directory" adds a directory to the X server's current
font path. To add a directory permanently, add a "FontPath" line
to your /etc/XF86Config file, in section "Files".
<20> "xset fp rehash" needs to be executed after calling mkfontdir on a
directory that is already contained in the X server's current font
path.
<20> "xfontsel" allows you to browse the installed fonts by selecting
various font properties.
<20> "xlsfonts -fn fontpattern" lists all fonts matching a font pattern.
Also displays various font properties. In particular, "xlsfonts -ll
-fn font" lists the font properties CHARSET_REGISTRY and
CHARSET_ENCODING, which together determine the font's encoding.
<20> "xfd -fn font" displays a font page by page.
The following fonts are freely available (not a complete list):
<20> The ones contained in XFree86, sometimes packaged in separate
packages. For example, SuSE has only normal 75dpi fonts in the
base `xf86' package. The other fonts are in the packages
`xfnt100', `xfntbig', `xfntcyr', `xfntscl'.
<20> The Emacs international fonts,
ftp://ftp.gnu.org/pub/gnu/intlfonts/intlfonts-1.2.tar.gz As already
mentioned, they are useful even if you prefer XEmacs to GNU Emacs
or don't use any Emacs at all.
2.3. X11 Unicode fonts
Applications wishing to display text belonging to different scripts
(like Cyrillic and Greek) at the same time, can do so by using
different X fonts for the various pieces of text. This is what
Netscape Communicator and Java do. However, this approach is more
complicated, because instead of working with `Font' and `XFontStruct',
the programmer has to deal with `XFontSet', and also because not all
fonts in the font set need to have the same dimensions.
<20> Markus Kuhn has assembled fixed-width 75dpi fonts with Unicode
encoding covering Latin, Greek, Cyrillic, Armenian, Georgian,
Hebrew scripts and many symbols. They cover ISO 8859 parts
1,2,3,4,5,7,8,9,10,13,14,15,16 all at once. These fonts are
required for running xterm in utf-8 mode. They are now contained in
XFree86 4.0.1, therefore you need to install them manually only if
you have an older XFree86 3.x version.
http://www.cl.cam.ac.uk/~mgk25/download/ucs-fonts.tar.gz.
<20> Markus Kuhn has also assembled double-width fixed 75dpi fonts with
Unicode encoding covering Chinese, Japanese and Korean. These fonts
are contained in XFree86 4.0.1 as well.
http://www.cl.cam.ac.uk/~mgk25/download/ucs-fonts-asian.tar.gz
<20> Roman Czyborra has assembled an 8x16 / 16x16 75dpi font with
Unicode encoding covering a huge part of Unicode. Download
unifont.hex.gz and hex2bdf from http://czyborra.com/unifont/. It
is not fixed-width: 8 pixels wide for European characters, 16
pixels wide for Chinese characters. Installation instructions:
$ gunzip unifont.hex.gz
$ hex2bdf < unifont.hex > unifont.bdf
$ bdftopcf -o unifont.pcf unifont.bdf
$ gzip -9 unifont.pcf
# cp unifont.pcf.gz /usr/X11R6/lib/X11/fonts/misc
# cd /usr/X11R6/lib/X11/fonts/misc
# mkfontdir
# xset fp rehash
<20> Primoz Peterlin has assembled an ETL family fonts covering Latin,
Greek, Cyrillic, Armenian, Georgian, Hebrew scripts.
ftp://ftp.x.org/contrib/fonts/etl-unicode.tar.gz Use the "bdftopcf"
program in order to install it.
<20> Mark Leisher has assembled a proportional, 17 pixel high (12
point), font, called ClearlyU, covering Latin, Greek, Cyrillic,
Armenian, Georgian, Hebrew, Thai, Laotian scripts.
http://crl.nmsu.edu/~mleisher/cu.html. Installation instructions:
$ bdftopcf -o cu12.pcf cu12.bdf
$ gzip -9 cu12.pcf
# cp cu12.pcf.gz /usr/X11R6/lib/X11/fonts/misc
# cd /usr/X11R6/lib/X11/fonts/misc
# mkfontdir
# xset fp rehash
2.4. Unicode xterm
xterm is part of X11R6 and XFree86, but is maintained separately by
Tom Dickey. http://www.clark.net/pub/dickey/xterm/xterm.html Newer
versions (patch level 146 and above) contain support for converting
keystrokes to UTF-8 before sending them to the application running in
the xterm, and for displaying Unicode characters that the application
outputs as UTF-8 byte sequence. It also contains support for double-
wide characters (mostly CJK ideographs) and combining characters,
contributed by Robert Brady <robert@suse.co.uk>.
To get an UTF-8 xterm running, you need to:
<20> Fetch http://www.clark.net/pub/dickey/xterm/xterm.tar.gz,
<20> Configure it by calling "./configure --enable-wide-chars ...", then
compile and install it.
<20> Have a Unicode fixed-width font installed. Markus Kuhn's ucs-
fonts.tar.gz (see above) is made for this.
<20> Start "xterm -u8 -fn '-misc-fixed-medium-r-
semicondensed--13-120-75-75-c-60-iso10646-1'". The option "-u8"
turns on Unicode and UTF-8 handling. The font designated by the
long "-fn" option is Markus Kuhn's Unicode font. Without this
option, the default font called "fixed" would be used, an
ISO-8859-1 6x13 font.
<20> Take a look at the sample files contained in Markus Kuhn's ucs-
fonts package:
$ cd .../ucs-fonts
$ cat quickbrown.txt
$ cat utf-8-demo.txt
You should be seeing (among others) greek and russian characters.
<20> To make xterm come up with UTF-8 handling each time it is started,
add the lines
xterm*utf8: 1
xterm*VT100*font: -misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso10646-1
xterm*VT100*wideFont: -misc-fixed-medium-r-normal-ja-13-125-75-75-c-120-iso10646-1
xterm*VT100*boldFont: -misc-fixed-bold-r-semicondensed--13-120-75-75-c-60-iso10646-1
to your $HOME/.Xdefaults (for yourself only). For CJK text processing
with double-width characters, the following settings are probably bet<65>
ter:
xterm*VT100*font: -Misc-Fixed-Medium-R-Normal--18-120-100-100-C-90-ISO10646-1
xterm*VT100*wideFont: -Misc-Fixed-Medium-R-Normal-ja-18-120-100-100-C-180-ISO10646-1
I don't recommend changing the system-wide /usr/X11R6/lib/X11/app-
defaults/XTerm, because then your changes will be erased next time you
upgrade to a new XFree86 version.
2.5. TrueType fonts
The fonts mentioned above are fixed size and not scalable. For some
applications, especially printing, high resolution fonts are
necessary, though. The most important type of scalable, high
resolution fonts are TrueType fonts. They are currently supported by
<20> XFree86 4.0.1; you need to add the line
Load "freetype"
or
Load "xtt"
to the "Module" section of your XF86Config file.
<20> The display engines of other operating systems.
<20> The yudit editor, see below, and its printing engine.
Some no-cost TrueType fonts with large Unicode coverage are
Bitstream Cyberbit
Covers Roman, Cyrillic, Greek, Hebrew, Arabic, combining
diacritical marks, Chinese, Korean, Japanese, and more.
Downloadable from
ftp://ftp.netscape.com/pub/communicator/extras/fonts/windows/Cyberbit.ZIP.
It is free for non-commercial purposes.
Microsoft Arial
Covers Roman, Cyrillic, Greek, Hebrew, Arabic, some combining
diacritical marks, Vietnamese.
Downloadable; look on a search engine for ftp-able files called
arial.ttf, ariali.ttf, arialbd.ttf, arialbi.ttf.
Lucida Sans Unicode
Covers Roman, Cyrillic, Greek, Hebrew, combining diacritical
marks.
Download: contained in IBM's JDK 1.3.0 for Linux, at
http://www.ibm.com/java/jdk/linux130/, or directly downloadable
as LucidaSansRegular.ttf and LucidaSansOblique.ttf from
ftp://ftp.maths.tcd.ie/Linux/opt/IBMJava2-13/jre/lib/fonts/.
Arphic
Cover Chinese (both traditional and simplified).
Download: at ftp://ftp.gnu.org/non-gnu/chinese-fonts-truetype/.
These fonts are truly free.
Download locations for these and other TrueType fonts can be found at
Christoph Singer's list of freely downloadable Unicode TrueType fonts
http://www.ccss.de/slovo/unifonts.htm.
Truetype fonts are installed similarly to fixed size fonts, except
that they go in a separate directory, and that ttmkfdir must be called
before mkfontdir:
# mkdir -p /usr/X11R6/lib/X11/fonts/truetype
# cp /somewhere/Cyberbit.ttf ... /usr/X11R6/lib/X11/fonts/truetype
# cd /usr/X11R6/lib/X11/fonts/truetype
# ttmkfdir > fonts.scale
# mkfontdir
# xset fp rehash
TrueType fonts can be converted to low resolution, non-scalable X11
fonts by use of Mark Leisher's ttf2bdf utility
ftp://crl.nmsu.edu/CLR/multiling/General/ttf2bdf-2.8-LINUX.tar.gz.
For example, to generate a proportional Unicode font for use with
cooledit:
# cd /usr/X11R6/lib/X11/fonts/local
# ttf2bdf ../truetrype/Cyberbit.ttf > cyberbit.bdf
# bdftopcf -o cyberbit.pcf cyberbit.bdf
# gzip -9 cyberbit.pcf
# mkfontdir
# xset fp rehash
More information about TrueType fonts can be found in the Linux
TrueType HOWTO http://www.moisty.org/~brion/linux/TrueType-HOWTO.html.
2.6. Miscellaneous
A small program which tests whether a Linux console or xterm is in
UTF-8 mode can be found in the
ftp://sunsite.unc.edu/pub/Linux/system/keyboards/x-lt-1.24.tar.gz
package by Ricardas Cepas, files testUTF-8.c and testUTF8.c. Most
applications should not use this, however: they should look at the
environment variables, see section "Locale environment variables".
3. Locale setup
3.1. Files & the kernel
You can now already use any Unicode characters in file names. No
kernel or file utilities need modifications. This is because file
names in the kernel can be anything not containing a null byte, and
'/' is used to delimit subdirectories. When encoded using UTF-8, non-
ASCII characters will never be encoded using null bytes or slashes.
All that happens is that file and directory names occupy more bytes
than they contain characters. For example, a filename consisting of
five greek characters will appear to the kernel as a 10-byte filename.
The kernel does not know (and does not need to know) that these bytes
are displayed as greek.
This is the general theory, as long as your files stay inside Linux.
On filesystems which are used from other operating systems, you have
mount options to control conversion of filenames to/from UTF-8:
<20> The "vfat" filesystems has a mount option "utf8". See
file:/usr/src/linux/Documentation/filesystems/vfat.txt. When you
give an "iocharset" mount option different from the default (which
is "iso8859-1"), the results with and without "utf8" are not
consistent. Therefore I don't recommend the "iocharset" mount
option.
<20> The "msdos", "umsdos" filesystems have the same mount option, but
it appears to have no effect.
<20> The "iso9660" filesystem has a mount option "utf8". See
file:/usr/src/linux/Documentation/filesystems/isofs.txt.
<20> Since Linux 2.2.x kernels, the "ntfs" filesystem has a mount option
"utf8". See file:/usr/src/linux/Documentation/filesystems/ntfs.txt.
The other filesystems (nfs, smbfs, ncpfs, hpfs, etc.) don't convert
filenames; therefore they support Unicode file names in UTF-8
encoding only if the other operating system supports them. Recall
that to enable a mount option for all future remounts, you add it
to the fourth column of the corresponding /etc/fstab line.
3.2. Upgrading the C library
glibc-2.2 supports multibyte locales, in particular UTF-8 locales. But
glibc-2.1.x and earlier C libraries do not support it. Therefore you
need to upgrade to glibc-2.2. Upgrading from glibc-2.1.x is riskless,
because glibc-2.2 is binary compatible with glibc-2.1.x (at least on
i386 platforms, and except for IPv6). Nevertheless, I recommend to
have a bootable rescue disk handy in case something goes wrong.
Prepare the kernel sources. You must have them unpacked and
configured. /usr/src/linux/include/linux/autoconf.h must exist.
Building the kernel is not needed.
Retrieve the glibc sources ftp://ftp.gnu.org/pub/gnu/glibc/, su to
root, then unpack, build and install it:
# unset LD_PRELOAD
# unset LD_LIBRARY_PATH
# tar xvfz glibc-2.2.tar.gz
# tar xvfz glibc-linuxthreads-2.2.tar.gz -C glibc-2.2
# mkdir glibc-2.2-build
# cd glibc-2.2-build
# ../glibc-2.2/configure --prefix=/usr --with-headers=/usr/src/linux/include --enable-add-ons
# make
# make check
# make info
# LC_ALL=C make install
# make localedata/install-locales
Upgrading from glibc versions earlier than 2.1.x cannot be done this
way; consider first installing a Linux distribution based on
glibc-2.1.x, and then upgrading to glibc-2.2 as described above.
Note that if -- for any reason -- you want to rebuild GCC after having
installed glibc-2.2, you need to first apply this patch gcc-
glibc-2.2-compat.diff to the GCC sources.
3.3. General data conversion
You will need a program to convert your locally (probably ISO-8859-1)
encoded texts to UTF-8. (The alternative would be to keep using texts
in different encodings on the same machine; this is not fun in the
long run.) One such program is `iconv', which comes with glibc-2.2.
Simply use
$ iconv --from-code=ISO-8859-1 --to-code=UTF-8 < old_file > new_file
Here are two handy shell scripts, called "i2u" i2u.sh (for ISO to UTF
conversion) and "u2i" u2i.sh (for UTF to ISO conversion). Adapt
according to your current 8-bit character set.
If you don't have glibc-2.2 and iconv installed, you can use GNU
recode 3.6 instead. "i2u" i2u_recode.sh is "recode
ISO-8859-1..UTF-8", and "u2i" u2i_recode.sh is "recode
UTF-8..ISO-8859-1".
ftp://ftp.gnu.org/pub/gnu/recode/recode-3.6.tar.gz
Or you can also use CLISP instead. Here are "i2u" i2u.lisp and "u2i"
u2i.lisp written in Lisp. Note: You need a CLISP version from July
1999 or newer.
ftp://clisp.cons.org/pub/lisp/clisp/source/clispsrc.tar.gz.
Other data conversion programs, less powerful than GNU recode, are
`trans' ftp://ftp.informatik.uni-
erlangen.de/pub/doc/ISO/charsets/trans113.tar.gz, `tcs' from the Plan9
operating system ftp://ftp.informatik.uni-
erlangen.de/pub/doc/ISO/charsets/tcs.tar.gz, and
`utrans'/`uhtrans'/`hutrans'
ftp://ftp.cdrom.com/pub/FreeBSD/distfiles/i18ntools-1.0.tar.gz by G.
Adam Stanislav <adam@whizkidtech.net>.
For the repeated conversion of files to UTF-8 from different character
sets, a semi-automatic tool can be used: to-utf8 presents the non-
ASCII parts of a file to the user, lets him decide about the file's
original character set, and then converts the file to UTF-8.
3.4. Locale environment variables
You may have the following environment variables set, containing
locale names:
LANGUAGE
override for LC_MESSAGES, used by GNU gettext only
LC_ALL
override for all other LC_* variables
LC_CTYPE, LC_MESSAGES, LC_COLLATE, LC_NUMERIC, LC_MONETARY, LC_TIME
individual variables for: character types and encoding, natural
language messages, sorting rules, number formatting, money
amount formatting, date and time display
LANG
default value for all LC_* variables
(See `man 7 locale' for a detailed description.)
Each of the LC_* and LANG variables can contain a locale name of the
following form:
language[_territory[.codeset]][@modifier]
where language is an ISO 639 language code (lower case), territory is
an ISO 3166 country code (upper case), codeset denotes a character
set, and modifier stands for other particular attributes (for example
indicating a particular language dialect, or a nonstandard
orthography).
LANGUAGE can contain several locale names, separated by colons.
In order to tell your system and all applications that you are using
UTF-8, you need to add a codeset suffix of UTF-8 to your locale names.
For example, if you were using
LC_CTYPE=de_DE
you would change this to
LC_CTYPE=de_DE.UTF-8
You do not need to change your LANGUAGE environment variable. GNU
gettext in glibc-2.2 has the ability to convert translations to the
right encoding.
3.5. Creating the locale support files
You create using localedef the support files for each UTF-8 locale you
intend to use, for example:
$ localedef -v -c -i de_DE -f UTF-8 de_DE.UTF-8
You typically don't need to create locales named "de" or "fr" without
country suffix, because these locales are normally only used by the
LANGUAGE variable and not by the LC_* variables, and LANGUAGE is only
used as an override for LC_MESSAGES.
4. Specific applications
4.1. Shells
4.1.1. bash
By default, GNU bash assumes that every character is one byte long and
one column wide. A patch for bash 2.04, by Marcin 'Qrczak' Kowalczyk
and Ricardas Cepas, teaches bash about multibyte characters in UTF-8
encoding. bash-2.04-diff
Double-width characters, combining characters and bidi are not
supported by this patch. It seems a complete redesign of the readline
redisplay engine is needed.
4.2. Networking
4.2.1. telnet
In some installations, telnet is not 8-bit clean by default. In order
to be able to send Unicode keystrokes to the remote host, you need to
set telnet into "outbinary" mode. There are two ways to do this:
$ telnet -L <host>
and
$ telnet
telnet> set outbinary
telnet> open <host>
4.2.2. kermit
The communications program C-Kermit
http://www.columbia.edu/kermit/ckermit.html, (an interactive tool for
connection setup, telnet, file transfer, with support for TCP/IP and
serial lines), in versions 7.0 or newer, understands the file and
transfer encodings UTF-8 and UCS-2, and understands the terminal
encoding UTF-8, and converts between these encodings and many others.
Documentation of these features can be found in
http://www.columbia.edu/kermit/ckermit2.html#x6.6.
4.3. Browsers
4.3.1. Netscape
Netscape 4.05 or newer can display HTML documents in UTF-8 encoding.
All a document needs is the following line between the <head> and
</head> tags:
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
Netscape 4.05 or newer can also display HTML and text files in UCS-2
encoding with byte-order mark.
http://www.netscape.com/computing/download/
4.3.2. Mozilla
Mozilla milestone M16 has much better internationalization than
Netscape 4. It can display HTML documents in UTF-8 encoding with
support for more languages. Alas, there is a cosmetic problem with CJK
fonts: some glyphs can be bigger than the line's height, thus
overlapping the previous or next line.
http://www.mozilla.org/
4.3.3. Amaya
Amaya 4.2.1 (http://www.w3.org/Amaya/,
http://www.w3.org/Amaya/User/SourceDist) has now limited handling of
UTF-8 encoded HTML pages. It recognizes the encoding, but it displays
only ISO-8859-1 and symbol characters; it only ever accesses the fonts
-adobe-times-*-iso8859-1
-adobe-helvetica-*-iso8859-1
-adobe-new century schoolbook-*-iso8859-1
-adobe-courier-*-iso8859-1
-adobe-symbol-*-adobe-fontspecific
Amaya is in fact a HTML editor, not only a browser. Amaya's strengths
among the browsers are its speed, given enough memory, and its
rendering of mathematical formulas (MathML support).
4.3.4. lynx
lynx-2.8 has an options screen (key 'O') which permits to set the
display character set. When running in an xterm or Linux console in
UTF-8 mode, set this to "UNICODE UTF-8". Note that for this setting to
take effect in the current browser session, you have to confirm on the
"Accept Changes" field, and for this setting to take effect in future
browser sessions, you have to enable the "Save options to disk" field
and then confirm it on the "Accept Changes" field.
Now, again, all a document needs is the following line between the
<head> and </head> tags:
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
When you are viewing text files in UTF-8 encoding, you also need to
pass the command-line option "-assume_local_charset=UTF-8" (affects
only file:/... URLs) or "-assume_charset=UTF-8" (affects all URLs).
In lynx-2.8.2 you can alternatively, in the options screen (key 'O'),
change the assumed document character set to "utf-8".
There is also an option in the options screen, to set the "preferred
document character set". But it has no effect, at least with file:/...
URLs and with http://... URLs served by apache-1.3.0.
There is a spacing and line-breaking problem, however. (Look at the
russian section of x-utf8.html, or at utf-8-demo.txt.)
Also, in lynx-2.8.2, configured with --enable-prettysrc, the nice
colour scheme does not work correctly any more when the display
character set has been set to "UNICODE UTF-8". This is fixed by a
simple patch lynx282.diff.
The Lynx developers say: "For any serious use of UTF-8 screen output
with lynx, compiling with slang lib and -DSLANG_MBCS_HACK is still
recommended."
Latest stable release:
ftp://ftp.gnu.org/pub/gnu/lynx/lynx-2.8.2.tar.gz
http://lynx.isc.org/
General home page: http://lynx.browser.org/
http://www.slcc.edu/lynx/
Newer development shapshots: http://lynx.isc.org/current/,
ftp://lynx.isc.org/current/
4.3.5. w3m
w3m by Akinori Ito http://ei5nazha.yz.yamagata-u.ac.jp/~aito/w3m/eng/
is a text mode browser for HTML pages and plain-text files. Its
layout of HTML tables, enumerations etc. is much prettier than lynx'
one. w3m can also be used as a high quality HTML to plain text
converter.
w3m 0.1.10 has command line options for the three major Japanese
encodings, but can also be used for UTF-8 encoded files. Without
command line options, you often have to press Ctrl-L to refresh the
display, and line breaking in Cyrillic and CJK paragraphs is not good.
To fix this, by Hironori Sakamoto has a patch
http://www2u.biglobe.ne.jp/~hsaka/w3m/ which adds UTF-8 as display
encoding.
4.3.6. Test pages
Some test pages for browsers can be found at the pages of Alan Wood
http://www.hclrss.demon.co.uk/unicode/#links and James Kass
http://home.att.net/~jameskass/.
4.4. Editors
4.4.1. yudit
yudit by G<>sp<73>r Sinai http://www.yudit.org/ is a first-class unicode
text editor for the X Window System. It supports simultaneous
processing of many languages, input methods, conversions for local
character standards. It has facilities for entering text in all
languages with only an English keyboard, using keyboard configuration
maps.
4.4.1.1. yudit-1.5
It can be compiled in three versions: Xlib GUI, KDE GUI, or Motif GUI.
Customization is very easy. Typically you will first customize your
font. From the font menu I chose "Unicode". Then, since the command
"xlsfonts '*-*-iso10646-1'" still showed some ambiguity, I chose a
font size of 13 (to match Markus Kuhn's 13-pixel fixed font).
Next, you will customize your input method. The input methods
"Straight", "Unicode" and "SGML" are most remarkable. For details
about the other built-in input methods, look in
/usr/local/share/yudit/data/.
To change the default for the next session, edit your $HOME/.yuditrc
file.
The general editor functionality is limited to editing, cut&paste and
search&replace. No undo.
4.4.1.2. yudit-2.1
This version is less easy to learn, because it comes with a homebrewn
GUI and no easily accessible help. But it has an undo functionality
and should therefore be more usable than version 1.5.
4.4.1.3. Fonts for yudit
yudit can display text using a TrueType font; see section "TrueType
fonts" above. The Bitstream Cyberbit gives good results. For yudit to
find the font, symlink it to /usr/local/share/yudit/data/cyberbit.ttf.
4.4.2. vim
vim (as of version 6.0r) has good support for UTF-8: when started in
an UTF-8 locale, it assumes UTF-8 encoding for the console and the
text files being edited. It supports double-wide (CJK) characters as
well and combining characters and therefore fits perfectly into UTF-8
enabled xterm.
Installation: Download from http://www.vim.org/. After unpacking the
four parts, call ./configure with --with-features=big --enable-
multibyte arguments (or edit src/Makefile to include the --with-
features=big and --enable-multibyte options). This will turn on the
feature FEAT_MBYTE. Then do "make" and "make install".
vim can be used to edit files in other encodings. For example, to edit
a BIG5 encoded file: :e ++cc=BIG5 filename. All encoding names
supported by iconv are accepted. Plus: vim automatically distinguishes
UTF-8 and ISO-8859-1 files without needing any command line option.
4.4.3. cooledit
cooledit by Paul Sheer http://www.cooledit.org/ is a good text editor
for the X Window System. Since version 3.15, it has support for
Unicode, including Bidi for Hebrew (but not Arabic).
A build error message message about a missing "vga_setpage" function
is worked around by adding "-DDO_NOT_USE_VGALIB" to the CFLAGS.
To view UTF-8 files in an UTF-8 locale you have to modify a setting in
the "Options -> Switches" panel: Enable the checkbox "Display
characters outside locale". I also found it necessary to disable
"Spellcheck as you type".
For viewing texts with both European and CJK characters, cooledit
needs a font which contains both, for example the GNU unifont (see
section "X11 Unicode fonts"): Start once
$ cooledit -fn -gnu-unifont-medium-r-normal--16-160-75-75-c-80-iso10646-1
cooledit will then use this font in all future invocations.
Unfortunately, the only characters that can be entered through the
keyboard are ISO-8859-1 characters and, through a cooledit specific
compose mechanism, ISO-8859-2 characters. Inputing arbitrary Unicode
characters in cooledit is possible, but a bit tedious.
4.4.4. emacs
First of all, you should read the section "International Character Set
Support" (node "International") in the Emacs manual. In particular,
note that you need to start Emacs using the command
$ emacs -fn fontset-standard
so that it will use a font set comprising a lot of international char<61>
acters.
In the short term, there are two packages for using UTF-8 in Emacs.
None of them needs recompiling Emacs.
<20> The emacs-utf package http://www.cs.ust.hk/faculty/otfried/Mule/ by
Otfried Cheong provides a "unicode-utf8" encoding to Emacs.
<20> The oc-unicode package http://www.cs.ust.hk/faculty/otfried/Mule/,
by Otfried Cheong, an extension of the Mule-UCS package
ftp://etlport.etl.go.jp/pub/mule/Mule-UCS/Mule-UCS-0.70.tar.gz
(mirrored at http://riksun.riken.go.jp/archives/misc/mule/Mule-
UCS/Mule-UCS-0.70.tar.gz and ftp://ftp.m17n.org/pub/mule/Mule-
UCS/Mule-UCS-0.70.tar.gz) by Hisashi Miyashita, provides a "utf-8"
encoding to Emacs.
You can use either of these packages, or both together. The advantages
of the emacs-utf "unicode-utf8" encoding are: it loads faster, and it
deals better with combining characters (important for Thai). The
advantage of the Mule-UCS / oc-unicode "utf-8" encoding is: it can
apply to a process buffer (such as M-x shell), not only to loading and
saving of files; and it respects the widths of characters better
(important for Ethiopian). However, it is less reliable: After heavy
editing of a file, I have seen some Unicode characters replaced with
U+FFFD after the file was saved. (But maybe that were bugs in Emacs
20.5 and 20.6 which are fixed in Emacs 20.7.)
To install the emacs-utf package, compile the program "utf2mule" and
install it somewhere in your $PATH, also install unicode.el,
muleuni-1.el, unicode-char.el somewhere. Then add the lines
(setq load-path (cons "/home/user/somewhere/emacs" load-path))
(if (not (string-match "XEmacs" emacs-version))
(progn
(require 'unicode)
;(setq unicode-data-path "..../UnicodeData-3.0.0.txt")
(if (eq window-system 'x)
(progn
(setq fontset12
(create-fontset-from-fontset-spec
"-misc-fixed-medium-r-normal-*-12-*-*-*-*-*-fontset-standard"))
(setq fontset13
(create-fontset-from-fontset-spec
"-misc-fixed-medium-r-normal-*-13-*-*-*-*-*-fontset-standard"))
(setq fontset14
(create-fontset-from-fontset-spec
"-misc-fixed-medium-r-normal-*-14-*-*-*-*-*-fontset-standard"))
(setq fontset15
(create-fontset-from-fontset-spec
"-misc-fixed-medium-r-normal-*-15-*-*-*-*-*-fontset-standard"))
(setq fontset16
(create-fontset-from-fontset-spec
"-misc-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard"))
(setq fontset18
(create-fontset-from-fontset-spec
"-misc-fixed-medium-r-normal-*-18-*-*-*-*-*-fontset-standard"))
; (set-default-font fontset15)
))))
to your $HOME/.emacs file. To activate any of the font sets, use the
Mule menu item "Set Font/FontSet" or Shift-down-mouse-1. The Unicode
coverage may of the font sets at different sizes may depend on the
installed fonts; here are screen shots at various sizes of
UTF-8-demo.txt ( 12, 13, 14, 15, 16, 18) and of the Mule script exam<61>
ples ( 12, 13, 14, 15, 16, 18). To designate a font set as the ini<6E>
tial font set for the first frame at startup, uncomment the set-
default-font line in the code snippet above.
To install the oc-unicode package, execute the command
$ emacs -batch -l oc-comp.el
and install the resulting file un-define.elc, as well as oc-uni<6E>
code.el, oc-charsets.el, oc-tools.el, somewhere. Then add the lines
(setq load-path (cons "/home/user/somewhere/emacs" load-path))
(if (not (string-match "XEmacs" emacs-version))
(progn
(require 'oc-unicode)
;(setq unicode-data-path "..../UnicodeData-3.0.0.txt")
(if (eq window-system 'x)
(progn
(setq fontset12
(oc-create-fontset
"-misc-fixed-medium-r-normal-*-12-*-*-*-*-*-fontset-standard"
"-misc-fixed-medium-r-normal-ja-12-*-iso10646-*"))
(setq fontset13
(oc-create-fontset
"-misc-fixed-medium-r-normal-*-13-*-*-*-*-*-fontset-standard"
"-misc-fixed-medium-r-normal-ja-13-*-iso10646-*"))
(setq fontset14
(oc-create-fontset
"-misc-fixed-medium-r-normal-*-14-*-*-*-*-*-fontset-standard"
"-misc-fixed-medium-r-normal-ja-14-*-iso10646-*"))
(setq fontset15
(oc-create-fontset
"-misc-fixed-medium-r-normal-*-15-*-*-*-*-*-fontset-standard"
"-misc-fixed-medium-r-normal-ja-15-*-iso10646-*"))
(setq fontset16
(oc-create-fontset
"-misc-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard"
"-misc-fixed-medium-r-normal-ja-16-*-iso10646-*"))
(setq fontset18
(oc-create-fontset
"-misc-fixed-medium-r-normal-*-18-*-*-*-*-*-fontset-standard"
"-misc-fixed-medium-r-normal-ja-18-*-iso10646-*"))
; (set-default-font fontset15)
))))
to your $HOME/.emacs file. You can choose your appropriate font set as
with the emacs-utf package.
In order to open an UTF-8 encoded file, you will type
M-x universal-coding-system-argument unicode-utf8 RET
M-x find-file filename RET
or
C-x RET c unicode-utf8 RET
C-x C-f filename RET
(or utf-8 instead of unicode-utf8, if you prefer oc-unicode/Mule-UCS).
In order to start a shell buffer with UTF-8 I/O, you will type
M-x universal-coding-system-argument utf-8 RET
M-x shell RET
(This works with oc-unicode/Mule-UCS only.)
There is a newer version Mule-UCS-0.81. Unfortunately you need to
rebuild emacs from source in order to use it.
Note that all this works with Emacs 20 in windowing mode only, not in
terminal mode. None of the mentioned packages works in Emacs 21, as of
this writing.
Richard Stallman plans to add integrated UTF-8 support to Emacs in the
long term, and so does the XEmacs developers group.
4.4.5. xemacs
(This section is written by Gilbert Baumann.)
Here is how to teach XEmacs (20.4 configured with MULE) the UTF-8
encoding. Unfortunately you need its sources to be able to patch it.
First you need these files provided by Tomohiko Morioka:
http://turnbull.sk.tsukuba.ac.jp/Tools/XEmacs/xemacs-21.0-b55-emc-
b55-ucs.diff and http://turnbull.sk.tsukuba.ac.jp/Tools/XEmacs/xemacs-
ucs-conv-0.1.tar.gz
The .diff is a diff against the C sources. The tar ball is elisp code,
which provides lots of code tables to map to and from Unicode. As the
name of the diff file suggests it is against XEmacs-21; I needed to
help `patch' a bit. The most notable difference to my XEmacs-20.4
sources is that file-coding.[ch] was called mule-coding.[ch].
For those unfamilar with the XEmacs-MULE stuff (as I am) a quick
guide:
What we call an encoding is called by MULE a `coding-system'. The most
important commands are:
M-x set-file-coding-system
M-x set-buffer-process-coding-system [comint buffers]
and the variable `file-coding-system-alist', which guides `find-file'
to guess the encoding used. After stuff was running, the very first
thing I did was this.
This code looks into the special mode line introduced by -*- somewhere
in the first 600 bytes of the file about to opened; if now there is a
field "Encoding: xyz;" and the xyz encoding ("coding system" in Emacs
speak) exists, choose that. So now you could do e.g.
;;; -*- Mode: Lisp; Syntax: Common-Lisp; Package: CLEX; Encoding: utf-8; -*-
and XEmacs goes into utf-8 mode here.
Atfer everything was running I defined \u03BB (greek lambda) as a
macro like:
(defmacro \u03BB (x) `(lambda .,x))
4.4.6. nedit
4.4.7. xedit
With XFree86-4.0.1, xedit is able to edit UTF-8 files if you set the
locale accordingly (see above), and add the line "Xedit*international:
true" to your $HOME/.Xdefaults file.
4.4.8. axe
As of version 6.1.2, aXe supports only 8-bit locales. If you add the
line "Axe*international: true" to your $HOME/.Xdefaults file, it will
simply dump core.
4.4.9. pico
As of version 4.30, pine cannot be reasonably used to view or edit
UTF-8 files. In UTF-8 enabled xterm, it has severe redraw problems.
4.4.10. mined98
mined98 is a small text editor by Michiel Huisjes, Achim M<>ller and
Thomas Wolff. http://www.inf.fu-berlin.de/~wolff/mined98.tar.gz It
lets you edit UTF-8 or 8-bit encoded files, in an UTF-8 or 8-bit
xterm. It also has powerful capabilities for entering Unicode
characters.
mined lets you edit both 8-bit encoded and UTF-8 encoded files. By
default it uses an autodetection heuristic. If you don't want to rely
on heuristics, pass the command-line option -u when editing an UTF-8
file, or +u when editing an 8-bit encoded file. You can change the
interpretation at any time from within the editor: It displays the
encoding ("L:h" for 8-bit, "U:h" for UTF-8) in the menu line. Click on
the first of these characters to change it.
mined knows about double-width and combining characters and displays
them correctly. It also has a special display mode for combining
characters.
mined also has a scrollbar and very nice pull-down menus. Alas, the
"Home", "End", "Delete" keys do not work.
4.4.11. qemacs
qemacs 0.2 is a small text editor by Fabrice Bellard. http://www-
stud.enst.fr/~bellard/qemacs/ with Emacs keybindings. It runs in an
UTF-8 console or xterm, and can edit both 8-bit encoded and UTF-8
encoded files. It still has a few rough edges, but further development
is underway.
4.5. Mailers
MIME: RFC 2279 defines UTF-8 as a MIME charset, which can be
transported under the 8bit, quoted-printable and base64 encodings. The
older MIME UTF-7 proposal (RFC 2152) is considered to be deprecated
and should not be used any further.
Mail clients released after January 1, 1999, should be capable of
sending and displaying UTF-8 encoded mails, otherwise they are
considered deficient. But these mails have to carry the MIME labels
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Simply piping an UTF-8 file into "mail" without caring about the MIME
labels will not work.
Mail client implementors should take a look at http://www.imc.org/imc-
intl/ and http://www.imc.org/mail-i18n.html.
Now about the individual mail clients (or "mail user agents"):
4.5.1. pine
The situation for an unpatched pine version 4.30 is as follows.
Pine does not do character set conversions. But it allows you to view
UTF-8 mails in an UTF-8 text window (Linux console or xterm).
Normally, Pine will warn about different character sets each time you
view an UTF-8 encoded mail. To get rid of this warning, choose S
(setup), then C (config), then change the value of "character-set" to
UTF-8. This option will not do anything, except to reduce the
warnings, as Pine has no built-in knowledge of UTF-8.
Also note that Pine's notion of Unicode characters is pretty limited:
It will display Latin and Greek characters, but not other kinds of
Unicode characters.
A patch by Robert Brady <robert@suse.co.uk>
http://www.ents.susu.soton.ac.uk/~robert/pine-utf8-0.1.diff adds UTF-8
support to Pine. With this patch, it decodes and prints headers and
bodies properly. The patch depends on the GNOME libunicode
http://cvs.gnome.org/lxr/source/libunicode/.
However, alignment remains broken in many places; replying to a mail
does not cause the character set to be converted as appropriate; and
the editor, pico, cannot deal with multibyte characters.
4.5.2. kmail
kmail (as of KDE 1.0) does not support UTF-8 mails at all.
4.5.3. Netscape Communicator
Netscape Communicator's Messenger can send and display mails in UTF-8
encoding, but it needs a little bit of manual user intervention.
To send an UTF-8 encoded mail: After opening the "Compose" window, but
before starting to compose the message, select from the menu "View ->
Character Set -> Unicode (UTF-8)". Then compose the message and send
it.
When you receive an UTF-8 encoded mail, Netscape unfortunately does
not display it in UTF-8 right away, and does not even give a visual
clue that the mail was encoded in UTF-8. You have to manually select
from the menu "View -> Character Set -> Unicode (UTF-8)".
For displaying UTF-8 mails, Netscape uses different fonts. You can
adjust your font settings in the "Edit -> Preferences -> Fonts"
dialog; choose the "Unicode" font category.
4.5.4. emacs (rmail, vm)
4.5.5. mutt
mutt-1.2.x, as available from http://www.mutt.org/, has only
rudimentary support for UTF-8: it can convert from UTF-8 into an 8-bit
display charset. The mutt-1.3.x development branch also supports UTF-8
as the display charset, so you can run Mutt in an UTF-8 xterm, and has
thorough support for MIME and charset conversion (relying on iconv).
4.5.6. exmh
exmh 2.1.2 with Tk 8.4a1 can recognize and correctly display UTF-8
mails (without CJK characters) if you add the following lines to your
$HOME/.Xdefaults file.
!
! Exmh
!
exmh.mimeUCharsets: utf-8
exmh.mime_utf-8_registry: iso10646
exmh.mime_utf-8_encoding: 1
exmh.mime_utf-8_plain_families: fixed
exmh.mime_utf-8_fixed_families: fixed
exmh.mime_utf-8_proportional_families: fixed
exmh.mime_utf-8_title_families: fixed
4.6. Text processing
4.6.1. groff
groff 1.16.1, the GNU implementation of the traditional Unix text
processing system troff/nroff, can output UTF-8 formatted text. Simply
use `groff -Tutf8' instead of `groff -Tlatin1' or `groff -Tascii'.
4.6.2. TeX
The teTeX 0.9 (and newer) distribution contains an Unicode adaptation
of TeX, called Omega (http://www.gutenberg.eu.org/omega/,
ftp://ftp.ens.fr/pub/tex/yannis/omega). Together with the unicode.tex
file contained in utf8-tex-0.1.tar.gz it enables you to use UTF-8
encoded sources as input for TeX. A thousand of Unicode characters are
currently supported.
All that changes is that you run `omega' (instead of `tex') or
`lambda' (instead of `latex'), and insert the following lines at the
head of your source input.
\ocp\TexUTF=inutf8
\InputTranslation currentfile \TexUTF
\input unicode
Other maybe related links: http://www.dante.de/projekte/nts/NTS-
FAQ.html, ftp://ftp.dante.de/pub/tex/language/chinese/CJK/.
4.7. Databases
4.7.1. PostgreSQL
PostgreSQL 6.4 or newer can be built with the configuration option
--with-mb=UNICODE.
4.7.2. Interbase
Borland/Inprise's Interbase 6.0 can store string fields in UTF-8
format if the option "CHARACTER SET UNICODE_FSS" is given.
4.8. Other text-mode applications
4.8.1. less
With http://www.flash.net/~marknu/less/less-358.tar.gz you can browse
UTF-8 encoded text files in an UTF-8 xterm or console. Make sure that
the environment variable LESSCHARSET is not set (or is set to utf-8).
If you also have a LESSKEY environment variable set, also make sure
that the file it points to does not define LESSCHARSET. If necessary,
regenerate this file using the `lesskey' command, or unset the LESSKEY
environment variable.
4.8.2. lv
lv-4.49.3 by Tomio Narita http://www.ff.iij4u.or.jp/~nrt/lv/ is a file
viewer with builtin character set converters. To view UTF-8 files in
an UTF-8 console, use "lv -Au8". But it can also be used to view files
in other CJK encodings in an UTF-8 console.
There is a small glitch: lv turns off xterm's cursor and doesn't turn
it on again.
4.8.3. expand
Get the GNU textutils-2.0 and apply the patch textutils-2.0.diff, then
configure, add "#define HAVE_FGETWC 1", "#define HAVE_FPUTWC 1" to
config.h. Then rebuild.
4.8.4. col, colcrt, colrm, column, rev, ul
Get the util-linux-2.9y package, configure it, then define
ENABLE_WIDECHAR in defines.h, change the "#if 0" to "#if 1" in
lib/widechar.h. In text-utils/Makefile, modify CFLAGS and LDFLAGS so
that they include the directories where libutf8 is installed. Then
rebuild.
4.8.5. figlet
figlet 2.2 has an option for UTF-8 input: "figlet -C utf8"
4.8.6. Base utilities
The Li18nux list of commands and utilities that ought to be made
interoperable with UTF-8 is as follows. Useful information needs to
get added here; I just didn't get around it yet :-)
As of glibc-2.2, regular expressions only work for 8-bit characters.
In an UTF-8 locale, regular expressions that contain non-ASCII
characters or that expect to match a single multibyte character with
"." do not work. This affects all commands and utilities listed
below.
alias
No info available yet.
ar No info available yet.
arch
No info available yet.
arp
No info available yet.
at As of at-3.1.8: The two uses of isalnum in at.c are invalid and
should be replaced with a use of quotearg.c or an exclude list
of the (fixed) list of shell metacharacters. The two uses of %8s
in at.c and atd.c are invalid and should become arbitrary
length.
awk
No info available yet.
basename
As of sh-utils-2.0i: OK.
batch
No info available yet.
bc No info available yet.
bg No info available yet.
bunzip2
No info available yet.
bzip2
No info available yet.
bzip2recover
No info available yet.
cal
No info available yet.
cat
No info available yet.
cd No info available yet.
cflow
No info available yet.
chgrp
As of fileutils-4.0u: OK.
chmod
As of fileutils-4.0u: OK.
chown
As of fileutils-4.0u: OK.
chroot
As of sh-utils-2.0i: OK.
cksum
As of textutils-2.0e: OK.
clear
No info available yet.
cmp
No info available yet.
col
No info available yet.
comm
No info available yet.
command
No info available yet.
compress
No info available yet.
cp As of fileutils-4.0u: OK.
cpio
No info available yet.
crontab
No info available yet.
csplit
No info available yet.
ctags
No info available yet.
cut
No info available yet.
date
As of sh-utils-2.0i: OK.
dd As of fileutils-4.0u: The conv=lcase, conv=ucase options don't
work correctly.
df As of fileutils-4.0u: OK.
diff
As of diffutils-2.7.2: the --side-by-side mode therefore doesn't
compute column width correctly.
diff3
No info available yet.
dirname
As of sh-utils-2.0i: OK.
domainname
No info available yet.
du As of fileutils-4.0u: OK.
echo
As of sh-utils-2.0i: OK.
ed No info available yet.
egrep
No info available yet.
env
As of sh-utils-2.0i: OK.
ex No info available yet.
expand
No info available yet.
expr
As of sh-utils-2.0i: The operators "match", "substr", "index",
"length" don't work correctly.
false
As of sh-utils-2.0i: OK.
fc No info available yet.
fg No info available yet.
fgrep
No info available yet.
file
No info available yet.
find
As of findutils-4.1.6: The "-iregex" does not work correctly;
this needs a fix in function find/parser.c:insert_regex.
fold
No info available yet.
ftp[BSD]
No info available yet.
fuser
No info available yet.
gencat
No info available yet.
getconf
No info available yet.
getopts
No info available yet.
gettext
No info available yet.
grep
No info available yet.
gunzip
No info available yet.
gzip
gzip-1.3 is UTF-8 capable, but it uses only English messages in
ASCII charset. Proper internationalization would require: Use
gettext. Call setlocale. In function check_ofname (file gzip.c),
use the function rpmatch from GNU text/sh/fileutils instead of
asking for "y" or "n". The use of strlen in gzip.c:852 is wrong,
needs to use the function mbswidth.
hash
No info available yet.
head
No info available yet.
hostname
As of sh-utils-2.0i: OK.
iconv
No info available yet.
id As of sh-utils-2.0i: OK.
ifconfig
No info available yet.
imake
No info available yet.
ipcrm
No info available yet.
ipcs
No info available yet.
jobs
No info available yet.
join
No info available yet.
kill
No info available yet.
killall
No info available yet.
ldd
No info available yet.
less
No complete info available yet.
lex
No info available yet.
ln As of fileutils-4.0u: OK.
locale
As of glibc-2.2: OK.
localedef
As of glibc-2.2: OK.
logger
No info available yet.
logname
As of sh-utils-2.0i: OK.
lp No info available yet.
lpc[BSD]
No info available yet.
lpq[BSD]
No info available yet.
lpr[BSD]
No info available yet.
lprm[BSD]
No info available yet.
lpstat(LEGACY)
No info available yet.
ls As of fileutils-4.0y: OK.
m4 No info available yet.
mailx
No info available yet.
make
No info available yet.
man
No info available yet.
mesg
No info available yet.
mkdir
As of fileutils-4.0u: OK.
mkfifo
As of fileutils-4.0u: OK.
mkfs
No info available yet.
mkswap
No info available yet.
more
No info available yet.
mount
No info available yet.
msgfmt
No info available yet.
msgmerge
No info available yet.
mv As of fileutils-4.0u: OK.
netstat
No info available yet.
newgrp
No info available yet.
nice
As of sh-utils-2.0i: OK.
nl No info available yet.
nohup
As of sh-utils-2.0i: OK.
nslookup
No info available yet.
nm No info available yet.
od No info available yet.
passwd[BSD]
No info available yet.
paste
No info available yet.
patch
No info available yet.
pathchk
As of sh-utils-2.0i: OK.
ping
No info available yet.
pr No info available yet.
printf
As of sh-utils-2.0i: OK.
ps No info available yet.
pwd
As of sh-utils-2.0i: OK.
read
No info available yet.
reboot
No info available yet.
renice
No info available yet.
rm As of fileutils-4.0u: OK.
rmdir
As of fileutils-4.0u: OK.
sed
No info available yet.
shar[BSD]
No info available yet.
shutdown
No info available yet.
sleep
As of sh-utils-2.0i: OK.
sort
No info available yet.
split
No info available yet.
strings
No info available yet.
strip
No info available yet.
stty
As of sh-utils-2.0.11: OK.
su[BSD]
No info available yet.
sum
As of textutils-2.0e: OK.
tail
No info available yet.
talk
No info available yet.
tar
As of tar-1.13.17: OK, if user and group names are always ASCII.
tclsh
No info available yet.
tee
As of sh-utils-2.0i: OK.
telnet
No info available yet.
test
As of sh-utils-2.0i: OK.
time
No info available yet.
touch
As of fileutils-4.0u: OK.
tput
No info available yet.
tr No info available yet.
true
As of sh-utils-2.0i: OK.
tsort
No info available yet.
tty
As of sh-utils-2.0i: OK.
type
No info available yet.
ulimit
No info available yet.
umask
No info available yet.
umount
No info available yet.
unalias
No info available yet.
uname
As of sh-utils-2.0i: OK.
uncompress
No info available yet.
unexpand
No info available yet.
uniq
No info available yet.
uudecode
No info available yet.
uuencode
No info available yet.
vi No info available yet.
wait
No info available yet.
wc As of textutils-2.0.8: OK.
who
As of sh-utils-2.0i: OK.
wish
No info available yet.
write
No info available yet.
xargs
As of findutils-4.1.5: The program uses strstr; a patch has been
submitted to the maintainer.
xgettext
No info available yet.
yacc
No info available yet.
zcat
No info available yet.
4.9. Other X11 applications
Owen Taylor is currently developing a library for rendering
multilingual text, called pango.
http://www.labs.redhat.com/~otaylor/pango/, http://www.pango.org/.
5. Printing
Since Postscript itself does not support Unicode fonts, the burden of
Unicode support in printing is on the program creating the Postscript
document, not on the Postscript renderer.
The existing Postscript fonts I've seen - .pfa/.pfb/.afm/.pfm/.gsf -
support only a small range of glyphs and are not Unicode fonts.
5.1. Printing using TrueType fonts
Both the uniprint and wprint programs produce good printed output for
Unicode plain text. They require a TrueType font; see section
"TrueType fonts" above. The Bitstream Cyberbit gives good results.
5.1.1. uniprint
The "uniprint" program contained in the yudit package can convert a
text file to Postscript. For uniprint to find the Cyberbit font,
symlink it to /usr/local/share/yudit/data/cyberbit.ttf.
5.1.2. wprint
The "wprint" (WorldPrint) program by Eduardo Trapani
http://ttt.esperanto.org.uy/programoj/angle/wprint.html postprocesses
Postscript output produced by Netscape Communicator or Mozilla from
HTML pages or plain text files.
The output is nearly perfect; only in Cyrillic paragraphs the line
breaking is incorrect: the lines are only about half as wide as they
should be.
5.1.3. Comparison
For plain text, uniprint has a better overall layout. On the other
hand, only wprint gets Thai output correct.
5.2. Printing using fixed-size fonts
Generally, printing using fixed-size fonts does not give an as
professional output as using TrueType fonts.
5.2.1. txtbdf2ps
The txtbdf2ps 0.7 program by Serge Winitzki
http://members.linuxstart.com/~winitzki/txtbdf2ps.html converts a
plain text file to Postscript, by use of a BDF font. Installation:
# install -m 777 txtbdf2ps-dev.txt /usr/local/bin/txtbdf2ps
Example with a proportional font:
$ txtbdf2ps -BDF=cyberbit.bdf -UTF-8 -nowrap < input.txt > output.ps
Example with a fixed-width font:
$ txtbdf2ps -BDF=unifont.bdf -UTF-8 -nowrap < input.txt > output.ps
Note: txtbdf2ps does not support combining characters and bidi.
5.3. The classical approach
Another way to print with TrueType fonts is to convert the TrueType
font to a Postscript font using the ttf2pt1 utility
(http://www.netspace.net.au/~mheath/ttf2pt1/,
http://quadrant.netspace.net.au/ttf2pt1/,
http://ttf2pt1.sourceforge.net/). Details can be found in Julius
Chroboczek's "Printing with TrueType fonts in Unix" writeup,
http://www.dcs.ed.ac.uk/home/jec/programs/xfsft/printing.html.
5.3.1. TeX, Omega
TODO: CJK, metafont, omega, dvips, odvips, utf8-tex-0.1
5.3.2. DocBook
TODO: db2ps, jadetex
5.3.3. groff -Tps
"groff -Tps" produces Postscript output. Its Postscript output driver
supports only a very limited number of Unicode characters (only what
Postscript supports by itself).
5.4. No luck with...
5.4.1. Netscape's "Print..."
As of version 4.72, Netscape Communicator cannot correctly print HTML
pages in UTF-8 encoding. You really have to use wprint.
5.4.2. Mozilla's "Print..."
As of version M16, printing of HTML pages is apparently not
implemented.
5.4.3. html2ps
As of version 1.0b1, the html2ps HTML to Postscript converter does not
support UTF-8 encoded HTML pages and has no special treatment of
fonts: the generated Postscript uses the standard Postscript fonts.
5.4.4. a2ps
As of version 4.12, a2ps doesn't support printing UTF-8 encoded text.
5.4.5. enscript
As of version 1.6.1, enscript doesn't support printing UTF-8 encoded
text. By default, it uses only the standard Postscript fonts, but it
can also include a custom Postscript font in the output.
6. Making your programs Unicode aware
6.1. C/C++
The C `char' type is 8-bit and will stay 8-bit because it denotes the
smallest addressable data unit. Various facilities are available:
6.1.1. For normal text handling
The ISO/ANSI C standard contains, in an amendment which was added in
1995, a "wide character" type `wchar_t', a set of functions like those
found in <string.h> and <ctype.h> (declared in <wchar.h> and
<wctype.h>, respectively), and a set of conversion functions between
`char *' and `wchar_t *' (declared in <stdlib.h>).
Good references for this API are
<20> the GNU libc-2.1 manual, chapters 4 "Character Handling" and 6
"Character Set Handling",
<20> the manual pages man-mbswcs.tar.gz, now contained in
ftp://ftp.win.tue.nl/pub/linux-local/manpages/man-
pages-1.29.tar.gz,
<20> the OpenGroup's introduction http://www.unix-
systems.org/version2/whatsnew/login_mse.html,
<20> the OpenGroup's Single Unix specification http://www.UNIX-
systems.org/online.html,
<20> the ISO/IEC 9899:1999 (ISO C 99) standard. The latest draft before
it was adopted is called n2794. You find it at
ftp://ftp.csn.net/DMK/sc22wg14/review/ or http://java-
tutor.com/docs/c/.
<20> Clive Feather's introduction http://www.lysator.liu.se/c/na1.html,
<20> the Dinkumware C library reference
http://www.dinkumware.com/htm_cl/.
Advantages of using this API:
<20> It's a vendor independent standard.
<20> The functions do the right thing, depending on the user's locale.
All a program needs to call is setlocale(LC_ALL,"");.
Drawbacks of this API:
<20> Some of the functions are not multithread-safe, because they keep a
hidden internal state between function calls.
<20> There is no first-class locale datatype. Therefore this API cannot
reasonably be used for anything that needs more than one locale or
character set at the same time.
<20> The OS support for this API is not good on most OSes.
6.1.1.1. Portability notes
A `wchar_t' may or may not be encoded in Unicode; this is platform and
sometimes also locale dependent. A multibyte sequence `char *' may or
may not be encoded in UTF-8; this is platform and sometimes also
locale dependent.
In detail, here is what the Single Unix specification says about the
`wchar_t' type: All wide-character codes in a given process consist of
an equal number of bits. This is in contrast to characters, which can
consist of a variable number of bytes. The byte or byte sequence that
represents a character can also be represented as a wide-character
code. Wide-character codes thus provide a uniform size for
manipulating text data. A wide-character code having all bits zero is
the null wide-character code, and terminates wide-character strings.
The wide-character value for each member of the Portable Character Set
(i.e. ASCII) will equal its value when used as the lone character in
an integer character constant. Wide-character codes for other
characters are locale- and implementation-dependent. State shift bytes
do not have a wide-character code representation.
One particular consequence is that in portable programs you shouldn't
use non-ASCII characters in string literals. That means, even though
you know the Unicode double quotation marks have the codes U+201C and
U+201D, you shouldn't write a string literal L"\u201cHello\u201d, he
said" or "\xe2\x80\x9cHello\xe2\x80\x9d, he said" in C programs.
Instead, use GNU gettext, write it as gettext("'Hello', he said"), and
create a message database en.po which translates "'Hello', he said" to
"\u201cHello\u201d, he said".
Here is a survey of the portability of the ISO/ANSI C facilities on
various Unix flavours.
GNU glibc-2.2.x
<20> <wchar.h> and <wctype.h> exist.
<20> Has wcs/mbs functions, fgetwc/fputwc/wprintf, everything.
<20> Has five UTF-8 locales.
<20> mbrtowc works.
GNU glibc-2.0.x, glibc-2.1.x
<20> <wchar.h> and <wctype.h> exist.
<20> Has wcs/mbs functions, but no fgetwc/fputwc/wprintf.
<20> No UTF-8 locale.
<20> mbrtowc returns EILSEQ for bytes >= 0x80.
AIX 4.3
<20> <wchar.h> and <wctype.h> exist.
<20> Has wcs/mbs functions, fgetwc/fputwc/wprintf, everything.
<20> Has many UTF-8 locales, one for every country.
<20> Needs -D_XOPEN_SOURCE=500 in order to define mbstate_t.
<20> mbrtowc works.
Solaris 2.7
<20> <wchar.h> and <wctype.h> exist.
<20> Has wcs/mbs functions, fgetwc/fputwc/wprintf, everything.
<20> Has the following UTF-8 locales: en_US.UTF-8, de.UTF-8,
es.UTF-8, fr.UTF-8, it.UTF-8, sv.UTF-8.
<20> mbrtowc returns -1/EILSEQ (instead of -2) for bytes >= 0x80.
OSF/1 4.0d
<20> <wchar.h> and <wctype.h> exist.
<20> Has wcs/mbs functions, fgetwc/fputwc/wprintf, everything.
<20> Has an add-on universal.utf8@ucs4 locale, see "man 5 unicode".
<20> mbrtowc does not know about UTF-8.
Irix 6.5
<20> <wchar.h> and <wctype.h> exist.
<20> Has wcs/mbs functions and fgetwc/fputwc, but not wprintf.
<20> Has no multibyte locales.
<20> Has only a dummy definition for mbstate_t.
<20> Doesn't have mbrtowc.
HP-UX 11.00
<20> <wchar.h> exists, <wctype.h> does not.
<20> Has wcs/mbs functions and fgetwc/fputwc, but not wprintf.
<20> Has a C.utf8 locale.
<20> Doesn't have mbstate_t.
<20> Doesn't have mbrtowc.
As a consequence, I recommend to use the restartable and multithread-
safe wcsr/mbsr functions, forget about those systems which don't have
them (Irix, HP-UX, AIX), and use the UTF-8 locale plug-in
libutf8_plug.so (see below) on those systems which permit you to
compile programs which use these wcsr/mbsr functions (Linux, Solaris,
OSF/1).
A similar advice, given by Sun in http://www.sun.com/software/white-
papers/wp-unicode/, section "Internationalized Applications with
Unicode", is:
To properly internationalize an application, use the following
guidelines:
1. Avoid direct access with Unicode. This is a task of the platform's
internationalization framework.
2. Use the POSIX model for multibyte and wide-character interfaces.
3. Only call the APIs that the internationalization framework provides
for language and cultural-specific operations.
4. Remain code-set independent.
If, for some reason, in some piece of code, you really have to assume
that `wchar_t' is Unicode (for example, if you want to do special
treatment of some Unicode characters), you should make that piece of
code conditional upon the result of is_locale_utf8(). Otherwise you
will mess up your program's behaviour in different locales or other
platforms. The function is_locale_utf8 is declared in utf8locale.h and
defined in utf8locale.c.
6.1.1.2. The libutf8 library
A portable implementation of the ISO/ANSI C API, which supports 8-bit
locales and UTF-8 locales, can be found in libutf8-0.7.3.tar.gz.
Advantages:
<20> Unicode UTF-8 support now, portably, even on OSes whose multibyte
character support does not work or which don't have multibyte/wide
character support at all.
<20> The same binary works in all OS supported 8-bit locales and in
UTF-8 locales.
<20> When an OS vendor adds proper multibyte character support, you can
take advantage of it by simply recompiling without -DHAVE_LIBUTF8
compiler option.
6.1.1.3. The Plan9 way
The Plan9 operating system, a variant of Unix, uses UTF-8 as character
encoding in all applications. Its wide character type is called
`Rune', not `wchar_t'. Parts of its libraries, written by Rob Pike and
Howard Trickey, are available at
ftp://ftp.cdrom.com/pub/netlib/research/9libs/9libs-1.0.tar.gz.
Another similar library, written by Alistair G. Crooks, is
ftp://ftp.cdrom.com/pub/NetBSD/packages/distfiles/libutf-2.10.tar.gz.
In particular, each of these libraries contains an UTF-8 aware regular
expression matcher.
Drawback of this API:
<20> UTF-8 is compiled in, not optional. Programs compiled in this
universe lose support for the 8-bit encodings which are still
frequently used in Europe.
6.1.2. For graphical user interface
The Qt-2.0 library http://www.troll.no/ contains a fully-Unicode
QString class. You can use the member functions QString::utf8 and
QString::fromUtf8 to convert to/from UTF-8 encoded text. The
QString::ascii and QString::latin1 member functions should not be used
any more.
6.1.3. For advanced text handling
The previously mentioned libraries implement Unicode aware versions of
the ASCII concepts. Here are libraries which deal with Unicode
concepts, such as titlecase (a third letter case, different from
uppercase and lowercase), distinction between punctuation and symbols,
canonical decomposition, combining classes, canonical ordering and the
like.
ucdata-2.4
The ucdata library by Mark Leisher
http://crl.nmsu.edu/~mleisher/ucdata.html deals with character
properties, case conversion, decomposition, combining classes.
The companion package ure-0.5
http://crl.nmsu.edu/~mleisher/ure-0.5.tar.gz is a Unicode
regular expression matcher.
ustring
The ustring C++ library by Rodrigo Reyes
http://ustring.charabia.net/ deals with character properties,
case conversion, decomposition, combining classes, and includes
a Unicode regular expression matcher.
ICU
International Components for Unicode
http://oss.software.ibm.com/icu/. IBM's very comprehensive
internationalization library featuring Unicode strings, resource
bundles, number formatters, date/time formatters, message
formatters, collation and more. Lots of supported locales.
Portable to Unix and Win32, but compiles out of the box only on
Linux libc6, not libc5.
libunicode
The GNOME libunicode library
http://cvs.gnome.org/lxr/source/libunicode/ by Tom Tromey and
others. It covers character set conversion, character
properties, decomposition.
6.1.4. For conversion
Two kinds of conversion libraries, which support UTF-8 and a large
number of 8-bit character sets, are available:
6.1.4.1. iconv
The iconv implementation by Ulrich Drepper, contained in the GNU
glibc-2.2. ftp://ftp.gnu.org/pub/gnu/glibc/glibc-2.2.tar.gz. The
iconv manpages are now contained in ftp://ftp.win.tue.nl/pub/linux-
local/manpages/man-pages-1.29.tar.gz.
The portable iconv implementation by Bruno Haible.
ftp://ftp.ilog.fr/pub/Users/haible/gnu/libiconv-1.5.1.tar.gz
The portable iconv implementation by Konstantin Chuguev.
<joy@urc.ac.ru>
ftp://ftp.urc.ac.ru/pub/local/OS/Unix/converters/iconv-0.4.tar.gz
Advantages:
<20> iconv is POSIX standardized, programs using iconv to convert
from/to UTF-8 will also run under Solaris. However, the names for
the character sets differ between platforms. For example, "EUC-JP"
under glibc is "eucJP" under HP-UX. (The official IANA name for
this character set is "EUC-JP", so it's clearly a HP-UX
deficiency.)
<20> On glibc-2.1 systems, no additional library is needed. On other
systems, one of the two other iconv implementations can be used.
6.1.4.2. librecode
librecode by Fran<61>ois Pinard
ftp://ftp.gnu.org/pub/gnu/recode/recode-3.6.tar.gz.
Advantages:
<20> Support for transliteration, i.e. conversion of non-ASCII
characters to sequences of ASCII characters in order to preserve
readability by humans, even when a lossless transformation is
impossible.
Drawbacks:
<20> Non-standard API.
<20> Slow initialization.
6.1.4.3. ICU
International Components for Unicode 1.7
http://oss.software.ibm.com/icu/. IBM's internationalization library
also has conversion facilities, declared in `ucnv.h'.
Advantages:
<20> Comprehensive set of supported encodings.
Drawbacks:
<20> Non-standard API.
6.1.5. Other approaches
libutf-8
libutf-8 by G. Adam Stanislav <adam@whizkidtech.net> contains a
few functions for on-the-fly conversion from/to UTF-8 encoded
`FILE*' streams.
http://www.whizkidtech.net/i18n/libutf-8-1.0.tar.gz
Advantages:
<20> Very small.
Drawbacks:
<20> Non-standard API.
<20> UTF-8 is compiled in, not optional. Programs compiled with this
library lose support for the 8-bit encodings which are still
frequently used in Europe.
<20> Installation is nontrivial: Makefile needs tweaking, not
autoconfiguring.
6.2. Java
Java has Unicode support built into the language. The type `char'
denotes a Unicode character, and the `java.lang.String' class denotes
a string built up from Unicode characters.
Java can display any Unicode characters through its windowing system
AWT, provided that 1. you set the Java system property "user.language"
appropriately, 2. the /usr/lib/java/lib/font.properties.language font
set definitions are appropriate, and 3. the fonts specified in that
file are installed. For example, in order to display text containing
japanese characters, you would install japanese fonts and run "java
-Duser.language=ja ...". You can combine font sets: In order to
display western european, greek and japanese characters
simultaneously, you would create a combination of the files
"font.properties" (covers ISO-8859-1), "font.properties.el" (covers
ISO-8859-7) and "font.properties.ja" into a single file. ??This is
untested??
The interfaces java.io.DataInput and java.io.DataOutput have methods
called `readUTF' and `writeUTF' respectively. But note that they don't
use UTF-8; they use a modified UTF-8 encoding: the NUL character is
encoded as the two-byte sequence 0xC0 0x80 instead of 0x00, and a 0x00
byte is added at the end. Encoded this way, strings can contain NUL
characters and nevertheless need not be prefixed with a length field -
the C <string.h> functions like strlen() and strcpy() can be used to
manipulate them.
6.3. Lisp
The Common Lisp standard specifies two character types: `base-char'
and `character'. It's up to the implementation to support Unicode or
not. The language also specifies a keyword argument `:external-
format' to `open', as the natural place to specify a character set or
encoding.
Among the free Common Lisp implementations, only CLISP
http://clisp.cons.org/ supports Unicode. You need a CLISP version from
March 2000 or newer.
ftp://clisp.cons.org/pub/lisp/clisp/source/clispsrc.tar.gz. The types
`base-char' and `character' are both equivalent to 16-bit Unicode.
The functions char-width and string-width provide an API comparable to
wcwidth() and wcswidth(). The encoding used for file or socket/pipe
I/O can be specified through the `:external-format' argument. The
encodings used for tty I/O and the default encoding for
file/socket/pipe I/O are locale dependent.
Among the commercial Common Lisp implementations:
LispWorks http://www.xanalys.com/software_tools/products/ supports
Unicode. The type `base-char' is equivalent to ISO-8859-1, and the
type `simple-char' (subtype of `character') contains all Unicode
characters. The encoding used for file I/O can be specified through
the `:external-format' argument, for example '(:UTF-8). Limitations:
Encodings cannot be used for socket I/O. The editor cannot edit UTF-8
encoded files.
Eclipse http://www.elwood.com/eclipse/eclipse.htm supports Unicode.
See http://www.elwood.com/eclipse/char.htm. The type `base-char' is
equivalent to ISO-8859-1, and the type `character' contains all
Unicode characters. The encoding used for file I/O can be specified
through a combination of the `:element-type' and `:external-format'
arguments to `open'. Limitations: Character attribute functions are
locale dependent. Source and compiled source files cannot contain
Unicode string literals.
The commercial Common Lisp implementation Allegro CL, in version 6.0,
has Unicode support. The types `base-char' and `character' are both
equivalent to 16-bit Unicode. The encoding used for file I/O can be
specified through the `:external-format' argument, for example
:external-format :utf8. The default encoding is locale dependent.
More details are at
http://www.franz.com/support/documentation/6.0/doc/iacl.htm.
6.4. Ada95
Ada95 was designed for Unicode support and the Ada95 standard library
features special ISO 10646-1 data types Wide_Character and
Wide_String, as well as numerous associated procedures and functions.
The GNU Ada95 compiler (gnat-3.11 or newer) supports UTF-8 as the
external encoding of wide characters. This allows you to use UTF-8 in
both source code and application I/O. To activate it in the
application, use "WCEM=8" in the FORM string when opening a file, and
use compiler option "-gnatW8" if the source code is in UTF-8. See the
GNAT (ftp://cs.nyu.edu/pub/gnat/) and Ada95
(ftp://ftp.cnam.fr/pub/Ada/PAL/userdocs/docadalt/rm95/index.htm)
reference manuals for details.
6.5. Python
Python 2.0 (http://www.python.org/2.0/,
http://www.python.org/pipermail/python-announce-
list/2000-October/000889.html,
http://starship.python.net/crew/amk/python/writing/new-python/new-
python.html) contains Unicode support. It has a new fundamental data
type `unicode', representing a Unicode string, a module `unicodedata'
for the character properties, and a set of converters for the most
important encodings. See
http://starship.python.net/crew/lemburg/unicode-proposal.txt, or the
file Misc/unicode.txt in the distribution, for details.
6.6. JavaScript/ECMAscript
Since JavaScript version 1.3, strings are always Unicode. There is no
character type, but you can use the \uXXXX notation for Unicode
characters inside strings. No normalization is done internally, so it
expects to receive Unicode Normalization Form C, which the W3C
recommends. See
http://developer.netscape.com/docs/manuals/communicator/jsref/js13.html#Unicode
for details and
http://developer.netscape.com/docs/javascript/e262-pdf.pdf for the
complete ECMAscript specification.
6.7. Tcl
Tcl/Tk started using Unicode as its base character set with version
8.1. Its internal representation for strings is UTF-8. It supports
the \uXXXX notation for Unicode characters. See
http://dev.scriptics.com/doc/howto/i18n.html.
6.8. Perl
Perl 5.6 stores strings internally in UTF-8 format, if you write
use utf8;
at the beginning of your script. length() returns the number of char<61>
acters of a string. For details, see the Perl-i18n FAQ at
http://rf.net/~james/perli18n.html.
Support for other (non-8-bit) encodings is available through the iconv
interface module http://cpan.perl.org/modules/by-module/Text/Text-
Iconv-1.1.tar.gz.
6.9. Related reading
Tomohiro Kubota has written an introduction to internationalization
http://www.debian.org/doc/manuals/intro-i18n/. The emphasis of his
document is on writing software that runs in any locale, using the
locale's encoding.
7. Other sources of information
7.1. Mailing lists
Broader audiences can be reached at the following mailing lists.
Note that where I write `at', you should write `@'. (Anti-spam
device.)
7.1.1. linux-utf8
Address: linux-utf8 at nl.linux.org
This mailing list is about internationalization with Unicode, and
covers a broad range of topics from the keyboard driver to the X11
fonts.
Archives are at http://mail.nl.linux.org/linux-utf8/.
To subscribe, send a message to majordomo at nl.linux.org with the
line "subscribe linux-utf8" in the body.
7.1.2. li18nux
Address: linux-i18n at sun.com
This mailing list is focused on organizing internationalization work
on Linux, and arranging meetings between people.
To subscribe, fill in the form at http://www.li18nux.org/ and send it
to linux-i18n-request at sun.com.
7.1.3. unicode
Address: unicode at unicode.org
This mailing list is focused on the standardization and continuing
development of the Unicode standard, and related technologies, such as
Bidi and sorting algorithms.
Archives are at ftp://ftp.unicode.org/Public/MailArchive/, but they
are not regularly updated.
For subscription information, see
http://www.unicode.org/unicode/consortium/distlist.html.
7.1.4. X11 internationalization
Address: i18n at xfree86.org
This mailing list addresses the people who work on better
internationalization of the X11/XFree86 system.
Archives are at http://devel.xfree86.org/archives/i18n/.
To subscribe, send mail to the friendly person at i18n-request at
xfree86.org explaining your motivation.
7.1.5. X11 fonts
Address: fonts at xfree86.org
This mailing list addresses the people who work on Unicode fonts and
the font subsystem for the X11/XFree86 system.
Archives are at http://devel.xfree86.org/archives/fonts/.
To subscribe, send mail to the overworked person at fonts-request at
xfree86.org explaining your motivation.
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