How to Add Multilanguage Support to a Yocto Build

How to add multilanguage support to a Yocto build?

The locales were not generated because the IMAGE_LINGUAS variable was overwritten into another place (my fault).

The locales generated with IMAGE_LINGUAS, e.g. "en_GB" or "en_US", does not have the ".UTF-8" suffix in their name but they use the UTF-8 encoding. To check if a locale is UTF-8 refer to: https://stackoverflow.com/a/42797421/5321161

How to check if a locale is UTF-8?

LC_IDENTIFICATION doesn't tell you much:

LC_IDENTIFICATION - this is not a user-visible category, it contains information about the locale itself and is rarely useful for users or developers (but is listed here for completeness sake).

You'd have to look at the complete set of files.

There appears to be no standard command-line utility for doing this, but there is a runtime call (added a little later than the original locale functions). Here is a sample program which illustrates the function nl_langinfo:

#include <stdio.h>
#include <locale.h>
#include <langinfo.h>

int
main(int argc, char **argv)
{
    int n;
    for (n = 1; n < argc; ++n) {
        if (setlocale(LC_ALL, argv[n]) != 0) {

            char *code = nl_langinfo(CODESET);
            if (code != 0)
                printf("%s ->%s\n", argv[n], code);
            else
                printf("?%s (nl_langinfo)\n", argv[n]);
        } else {
            printf("? %s (setlocale)\n", argv[n]);
        }
    }
    return 0;
}

and some output, e.g., by foo $(locale -a):

aa_DJ ->ISO-8859-1
aa_DJ.iso88591 ->ISO-8859-1
aa_DJ.utf8 ->UTF-8
aa_ER ->UTF-8
aa_ER@saaho ->UTF-8
aa_ER.utf8 ->UTF-8
aa_ER.utf8@saaho ->UTF-8
aa_ET ->UTF-8
aa_ET.utf8 ->UTF-8
af_ZA ->ISO-8859-1
af_ZA.iso88591 ->ISO-8859-1
af_ZA.utf8 ->UTF-8
am_ET ->UTF-8
am_ET.utf8 ->UTF-8
an_ES ->ISO-8859-15
an_ES.iso885915 ->ISO-8859-15
an_ES.utf8 ->UTF-8
ar_AE ->ISO-8859-6
ar_AE.iso88596 ->ISO-8859-6
ar_AE.utf8 ->UTF-8
ar_BH ->ISO-8859-6
ar_BH.iso88596 ->ISO-8859-6

The directory names you're referring to are often (but not required) to be the same as encoding names. That is the assumption made in the example program. There was a related question in How to get terminal's Character Encoding, but it has no useful answers. One is interesting though, since it asserts that

locale charmap

will give the locale encoding. According to the standard, that's not necessarily so:

• The command locale charmap gives the name used in localedef -f

• However, localedef attaches no special meaning to the name given in the -f option.

• localedef has a different option -u which identifies the codeset, but locale (in the standard) mentions no method for displaying this information.

As usual, implementations may (or may not) treat unspecified features in different ways. The GNU C library's documentation differs in some respects from the standard (see locale and localedef), but offers no explicit options for showing the codeset name.

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