bindtextdomain man page
bindtextdomain — set directory containing message catalogs
#include <libintl.h> char * bindtextdomain (const char * domainname, const char * dirname);
The bindtextdomain function sets the base directory of the hierarchy containing message catalogs for a given message domain.
A message domain is a set of translatable msgid messages. Usually, every software package has its own message domain. The need for calling bindtextdomain arises because packages are not always installed with the same prefix as the <libintl.h> header and the libc/libintl libraries.
Message catalogs will be expected at the pathnames dirname/locale/category/domainname.mo, where locale is a locale name and category is a locale facet such as LC_MESSAGES.
domainname must be a non-empty string.
If dirname is not NULL, the base directory for message catalogs belonging to domain domainname is set to dirname. The function makes copies of the argument strings as needed. If the program wishes to call the chdir function, it is important that dirname be an absolute pathname; otherwise it cannot be guaranteed that the message catalogs will be found.
If dirname is NULL, the function returns the previously set base directory for domain domainname.
If successful, the bindtextdomain function returns the current base directory for domain domainname, after possibly changing it. The resulting string is valid until the next bindtextdomain call for the same domainname and must not be modified or freed. If a memory allocation failure occurs, it sets errno to ENOMEM and returns NULL.
The following error can occur, among others:
Not enough memory available.
The return type ought to be const char *, but is char * to avoid warnings in C code predating ANSI C.
gettext(3), dgettext(3), dcgettext(3), ngettext(3), dngettext(3), dcngettext(3), textdomain(3), realpath(3)
gettext(3), maketext(1), textdomain(3).