Section 6.8. Internationalization (I18N)

6.8. Internationalization (I18N)^[26]

^[26] Refer to www.li18nux.org/ to learn more about the Linux I18N Project.

How I18N affects the porting effort greatly depends on the application. If an application requires simple message catalogue conversions, date and time displays, or simple text string searches using regular expressions, porting these functionalities from HP-UX to Linux can be easy. However, if the application does more complicated text analysis, such as ones used in editors, those may be harder to port for the reason mentioned in the next paragraph.

Both HP-UX and Linux conform to the ISO naming standard locale names, [locale][_territory].[codeset], where locale is the two-character language, and territory is the two-character territory. Examples of these are en_US.iso885915 and zh_CN.gb18030. However, the locales available on each system, and locale contents, are different. Porting applications that require complicated use of available locales may require the need to learn language specificity and translation as well as modification of existing locales on Linux to get similar behavior as on HP-UX.

Table 6-12 compares HP-UX and GNU libc API support related to I18N.

Table 6-12. HP-UX and GNU libc I18N Support Comparison Table

HP-UX	GNU libc	Functions
wcscat, wcsncat, wcscmp, wcsncmp, wcscpy, wcsncpy, wcslen, wcschr, wcsrchr, wcsstr, wcspbrk, wcsspn, wcscspn, wcswcs, wcstok, wcscoll, wcwidth, wcswidth, wcsxfrm	wcscat, wcsncat, wcscmp, wcsncmp, wcscpy, wcsncpy, wcslen, wcschr, wcsrchr, wcsstr, wcspbrk, wcsspn, wcscspn, wcswcs, wcstok, wcscoll, wcwidth, wcswidth, wcsxfrm	Wide character string functions
mblen, mbrlen, wcslen, strlen, wcswidth, wcwidth	mblen, mbrlen, wcslen, strlen, wcswidth, wcwidth	Dimension functions
mbsinit, mbrtowc, wcrtomb, mbsrtowcs, wcsrtombs, btowc, wctob, mbtowc, mbstowcs, wctomb, wcstombs	mbsinit, mbrtowc, wcrtomb mbsrtowcs, wcsrtombs, btowc, wctob, mbtowc, mbstowcs wctomb, wcstombs, wcrtomb, wcsnrtombs, mbsnrtowcs	Conversion functions
iconv, iconv_open, iconv_close, genxlt	iconv, iconv_open, iconv_close	Translation functions
ngettext, dngettext, dcngettext, setlocale, textdomain, bindtextdomain, bind_textdomain_codeset, msgfmt, dumpmsg, findmsg, gencat, catclose, catopen	ngettext, dngettext, dcngettext setlocale, texTDomain, bindtextdomain, bind_textdomain_codeset, gettext, dgettext, dcgettext, catgets, gencat, catclose, catopen	Message catalogue functions
getc, getc_unlocked, getchar, getchar_unlocked, fgetc, getw, putc, putchar, fputc, putw, fgetc, getw, ungetwc, getwc, getwchar, fgetwc	getc, getc_unlocked, getchar getchar_unlockec, fgetc, getw, putc, putchar, fputc, putw, fgetc, getw, ungetwc, getwc, getwchar, fgetwc, ungetwc, fgets, ungetc, fputwc, fputws, putwc, putwchar, fputs, fgetws	Input/output functions
fwprintf, wprintf, swprintf, vfwprintf, vwprintf, vswprintf, strftime, strfmon, printf, fprintf, sprintf, wcfstime, vprintf, vfprintf, vsprintf, vsnprintf	fwprintf, wprintf, swprintf, vfwprintf, vwprintf, vswprintf, strftime, strfmon, printf, fprintf, sprintf, wcfstime, vprintf, vfprintf, vsprintf, vsnprintf	String formatting functions
iswalpha, iswupper, iswlower, iswdigit, iswxdigit, iswalnum, iswspace, iswpunct, iswprint, iswgraph, iswcntrl, wctype, iswctype, isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii	iswalpha, iswupper, iswlower iswdigit, iswxdigit, iswalnum iswspace, iswpunct, iswprint iswgraph, iswcntrl, wctype, iswctype, isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii, isblank, isspace, isupper	Character classifications
strcoll, strxfrm, wcscoll, wcwidth, wcswidth, wcsxfrm	strcoll, strxfrm, wcscoll, wcsxfrm	Collation functions
regcomp, regerror, regexec, regfree	regcomp, regexec, regerror, regfree	Regular expressions
memset, wmemchr, wmemcmp, wmemcpy, wmemmove, wmemset	memset, wmemchr, wmemcmp wmemcpy, wmemmove, wmemset, wcpcpy, wcpncpy, wcscpy, wcsncpy, wcsspn, cpcpy, cpncpy, cscpy, csncpy, csspn	String copying and filling functions
towlower, towupper, towctrans, wctrans, tolower, toupper	towlower, towupper, towctrans, wctrans, tolower, toupper	Conversion functions

On HP-UX, the decoder file is located in /usr/lib/nls/config. On Linux, you can find the decoder file in /usr/share/locale/locale.alias. On Linux, you can use the command locale -a to determine the locales installed on the system.

6.8.1. iconv Support and Message Catalogs

Linux provides the iconv(1) utility to convert traditional string encoding to unicode. To get a list of currently implemented encodings in Linux, use the iconv -list command at the Linux command prompt. In HP-UX, the file /usr/lib/nls/iconv/config.iconv lists the implemented encoding. See Chapter 3 for examples of using libiconv APIs and how to create a message catalog.