1 Overview

The GNU hello program (https://www.gnu.org/software/hello/) produces a familiar, friendly greeting. It allows nonprogrammers to use a classic computer science tool which would otherwise be unavailable to them. Because it is protected by the GNU General Public License, users are free (in perpetuity) to share and change it.

Not to spoil the joke, but of course the practical purpose of GNU Hello is to serve as a minimal example of a GNU package. So, although most manuals don’t need to discuss the implementation of the programs they document, that is part of the goal here.

First, GNU Hello follows the GNU coding standards (see Preface in GNU Coding Standards) and GNU maintainer standards (see Preface in Information for GNU Maintainers). These are the basic documents which all GNU packages should adhere to.

The Hello package also implements recommended development practices not embodied in the standards, using other GNU packages and features:

• It uses Automake (see Introduction in GNU Automake) and hence also Autoconf (see Introduction in GNU Autoconf) for configuration.
• It uses Gnulib (see Introduction in GNU Gnulib) to enhance portability and avoid duplication of common sources. Both gnulib-tool and srclist-update are used, for purposes of example. See the README-dev file in the distribution.
• GNU Gettext (see Introduction in GNU Gettext) is used for internationalization support. Hello’s greeting has been translated into many languages.
• Internally, Hello uses the GNU getopt_long function (see Getopt Long Options in GNU C Library) to parse options, thus supporting GNU-style long options such as --help.
• The Hello Man page is generated with GNU help2man (see Overview in GNU help2man) from the --help output. This relieves the maintainers from the burden of updating separate man documentation, yet provides a reasonable overview for man devotees.
• Finally, Texinfo (see Introduction in Texinfo) is the documentation format for this manual. It supports output in Info, HTML, PDF, DVI, plain text, XML, and other formats.

GNU Hello is implemented in C. The GNU Gettext distribution contains “hello world” examples in many other programming languages; see the Gettext home page at https://www.gnu.org/software/gettext/.

The top-level Makefile.am in Hello also contains a few special targets for other projects to adapt as desired:

diff

Make a diff from the previous release, assuming the current tarball is in the current tarball.

po-check

Verify that all source files using _() are included for translation in po/POTFILES.in, so translators will have all the messages.

wwwdoc

Sample procedure for updating the manual on the GNU web site, in this case https://www.gnu.org/software/hello/manual/.

GNU Hello was written by Mike Haertel, David MacKenzie, Jan Brittenson, Charles Hannum, Roland McGrath, Noah Friedman, Karl Eichwalder, Karl Berry, and The King.