Once you have completed translating your message catalogs, the msgfmt utility is used to create binary “machine object” (MO) versions of your catalogs. Once that is done, all that is left is to install the message catalogs and test the program.
In real projects on Linux, the paths where message catalogs will be installed are configured when you run autoconf's1 ./configure script. Usually the ./configure script is responsible for creating a config.h header file that contains the actual path that will be passed to bindtextdomain(). Additionally, in a real project you would run msgfmt and the installation routines from a project's Makefile.
Now that we understand how to get localized text messages into a Linux program, let's examine the infrastructure underlying the display of those messages on the desktop.
1. Autoconf is a tool used to create shell scripts used for automatically configuring source code software packages on Linux/Unix systems: http://www.gnu.org/software/autoconf.