Added version number and online help.

hello.1

@@ -1,18 +1,24 @@
 .\" hello.1
-.TH HELLO 1 "Nov. 2007" "heinzel" "User Commands"
+.TH HELLO 1 "Jan. 2011" "heinzel" "User Commands"
 
 .SH NAME
 hello \- Send greetings to everyone
 
 .SH SYNOPSIS
-.B hello
+.B hello 
+.B [\fIOPTION\fR]
 
 .SH DESCRIPTION
 .B hello
 print the message "Hello World." to standard output.
 
 .SH OPTIONS
-none
+.TP
+.B -h
+Print a short help text.
+.TP
+.B -V
+Print the version number.
 
 .SH BUGS
 .B hello

hello.c

@@ -2,11 +2,79 @@
  * hello.c
  */
 
+// err()
+#include <err.h>
+// getopt()
+#include <unistd.h>
+// basename()
+#include <libgen.h>
+// printf(), fprintf()
 #include <stdio.h>
+// exit()
 #include <stdlib.h>
+// strdup()
+#include <string.h>
+// EX_... constants
 #include <sysexits.h>
 
+/* Symbols */
+#define VERSION "0.1"
+
+/* Prototypes */
+void print_version(void);
+void print_help(void);
+
+/* Global Objects */
+char *progname;
+
+/*
+ * main
+ */
 int main(int argc, char** argv) {
+	char c;
+
+	/* Store program name without path
+	 * (will be used in e.g. error messages) */
+	if( (progname = strdup(basename(argv[0]))) == NULL )
+		err(EX_OSERR, NULL);
+
+	while( (c = getopt(argc, argv, "hV")) >= 0 ) {
+		switch(c) {
+		case 'h':
+			print_help();
+			exit(EX_OK);
+		case 'V':
+			print_version();
+			exit(EX_OK);
+		case '?':
+			fprintf(stderr, "Try `-h´ for more information.\n");
+			exit(EX_USAGE);
+		default:
+			fprintf(stderr, "getopt() is on fire.\n");
+			exit(EX_SOFTWARE);
+		}
+	}
+	if(optind < argc) {
+		fprintf(stderr, "%s: Invalid argument: %s\n", progname, argv[optind]);
+		fprintf(stderr, "Try `-h´ for more information.\n");
+		exit(EX_USAGE);
+	}
+
 	printf("Hello World.\n");
 	exit(EX_OK);
 }
+
+void print_version(void) {
+	printf("%s %s\n", progname, VERSION);
+}
+
+void print_help(void) {
+	printf("hello - Send greetings to everyone\n");
+	printf("\n");
+	printf("Usage: %s [-hV]\n\n", progname);
+	printf("Options:\n");
+	printf(" -h         Print this help text.\n");
+	printf(" -V         Print version number.\n");
+	printf("\n");
+}
+