GNU の「Hello World」に勝るのはかなり難しいと思います(tar を表示して、テスト、makefile(s!)、man などを含めて、完全に楽しむことができます):
/* hello.c -- print a greeting message and exit.
Copyright 1992, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2005,
2006, 2007, 2008 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#include "system.h"
/* String containing name the program is called with. */
const char *program_name;
static const struct option longopts[] =
{
{ "greeting", required_argument, NULL, 'g' },
{ "help", no_argument, NULL, 'h' },
{ "next-generation", no_argument, NULL, 'n' },
{ "traditional", no_argument, NULL, 't' },
{ "version", no_argument, NULL, 'v' },
{ NULL, 0, NULL, 0 }
};
/* Different types of greetings; only one per invocation. */
typedef enum {
greet_gnu, greet_new, greet_traditional, greet_user
} greeting_type;
/* Forward declarations. */
static void print_help (void);
static void print_version (void);
int
main (int argc, char *argv[])
{
int optc;
int lose = 0;
const char *greeting_msg = NULL;
greeting_type g = greet_gnu;
program_name = argv[0];
/* Set locale via LC_ALL. */
setlocale (LC_ALL, "");
#if ENABLE_NLS
/* Set the text message domain. */
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
#endif
/* Even exiting has subtleties. On exit, if any writes failed, change
the exit status. The /dev/full device on GNU/Linux can be used for
testing; for instance, hello >/dev/full should exit unsuccessfully.
This is implemented in the Gnulib module "closeout". */
atexit (close_stdout);
while ((optc = getopt_long (argc, argv, "g:hntv", longopts, NULL)) != -1)
switch (optc)
{
/* --help and --version exit immediately, per GNU coding standards. */
case 'v':
print_version ();
exit (EXIT_SUCCESS);
break;
case 'g':
greeting_msg = optarg;
g = greet_user;
break;
case 'h':
print_help ();
exit (EXIT_SUCCESS);
break;
case 'n':
g = greet_new;
break;
case 't':
g = greet_traditional;
break;
default:
lose = 1;
break;
}
if (lose || optind < argc)
{
/* Print error message and exit. */
if (optind < argc)
fprintf (stderr, _("%s: extra operand: %s\n"),
program_name, argv[optind]);
fprintf (stderr, _("Try `%s --help' for more information.\n"),
program_name);
exit (EXIT_FAILURE);
}
/* Print greeting message and exit. */
if (g == greet_traditional)
printf (_("hello, world\n"));
else if (g == greet_new)
/* TRANSLATORS: Use box drawing characters or other fancy stuff
if your encoding (e.g., UTF-8) allows it. If done so add the
following note, please:
[Note: For best viewing results use a UTF-8 locale, please.]
*/
printf (_("\
+---------------+\n\
| Hello, world! |\n\
+---------------+\n\
"));
else if (g == greet_user)
puts (greeting_msg);
else if (g == greet_gnu)
puts (_("Hello, world!"));
else {
/* No need for this impossible message to be translated. */
fprintf (stderr, "Impossible hello value %d\n", g);
exit (EXIT_FAILURE);
}
exit (EXIT_SUCCESS);
}
/* Print help info. This long message is split into
several pieces to help translators be able to align different
blocks and identify the various pieces. */
static void
print_help (void)
{
/* TRANSLATORS: --help output 1 (synopsis)
no-wrap */
printf (_("\
Usage: %s [OPTION]...\n"), program_name);
/* TRANSLATORS: --help output 2 (brief description)
no-wrap */
fputs (_("\
Print a friendly, customizable greeting.\n"), stdout);
puts ("");
/* TRANSLATORS: --help output 3: options 1/2
no-wrap */
fputs (_("\
-h, --help display this help and exit\n\
-v, --version display version information and exit\n"), stdout);
puts ("");
/* TRANSLATORS: --help output 4: options 2/2
no-wrap */
fputs (_("\
-t, --traditional use traditional greeting format\n\
-n, --next-generation use next-generation greeting format\n\
-g, --greeting=TEXT use TEXT as the greeting message\n"), stdout);
printf ("\n");
/* TRANSLATORS: --help output 5 (end)
TRANSLATORS: the placeholder indicates the bug-reporting address
for this application. Please add _another line_ with the
address for translation bugs.
no-wrap */
printf (_("\
Report bugs to <%s>.\n"), PACKAGE_BUGREPORT);
}
/* Print version and copyright information. */
static void
print_version (void)
{
printf ("hello (GNU %s) %s\n", PACKAGE, VERSION);
/* xgettext: no-wrap */
puts ("");
/* It is important to separate the year from the rest of the message,
as done here, to avoid having to retranslate the message when a new
year comes around. */
printf (_("\
Copyright (C) %s Free Software Foundation, Inc.\n\
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>\n\
This is free software: you are free to change and redistribute it.\n\
There is NO WARRANTY, to the extent permitted by law.\n"),
"2008");
}