msgfmt

#include <stdio.h>
#include <libintl.h> // gettext
#include <locale.h>
 
#define _(STRING) gettext(STRING)
#define PACKAGE "hello"
#define LOCALEDIR "/usr/share/locale/"
 
int main(int argv, char* argc[])
{
	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);
	printf(_("Hello, World\n"));
	printf(_("This is a example.\n"));
	return 0;
}

xgettext --keyword=_ hello.c -o hello.pot

...
msgid "Hello, World\n"
msgstr "大家好！\n"
msgid "This is a example.\n"
msgstr "This is a example.\n"
...

msgmerge zh_CN.po hello.pot
msgfmt zh_CN.po -o hello.mo