usage: add short and long options and descriptions to usage()

Earlier usage did not help users.

diff --git a/mtr.c b/mtr.c
index 608142164f8c2be30e009425d3cb3d328710e89b..f4bbf1083cc84c172ad61d302c471b86a0a0bbde 100644 (file)
--- a/mtr.c
+++ b/mtr.c
@@ -128,6 +128,54 @@ typedef struct names {
 } names_t;
 static names_t *names = NULL;
 
+
+static void __attribute__((__noreturn__)) usage(FILE *out)
+{
+  fputs("\nUsage:\n", out);
+  fputs(" mtr [options] hostname\n", out);
+  fputs("\n", out);
+  fputs(" -F, --filename FILE        read hostname(s) from a file\n", out);
+  fputs(" -4                         use IPv4 only\n", out);
+  fputs(" -6                         use IPv6 only\n", out);
+  fputs(" -u, --udp                  use udp instead of icmp echo\n", out);
+  fputs(" -T, --tcp                  use tcp instead of icmp echo\n", out);
+  fputs(" -a, --address ADDRESS      bind the outgoing socket to ADDRESS\n", out);
+  fputs(" -f, --first-ttl NUMBER     set what TTL to start\n", out);
+  fputs(" -m, --max-ttl NUMBER       maximum number of hops\n", out);
+  fputs(" -U, --max-unknown NUMBER   maximum unknown host\n", out);
+  fputs(" -P, --port PORT            target port number for tcp, sctp, or udp\n", out);
+  fputs(" -L, --localport LOCALPORT  source port number for udp\n", out);
+  fputs(" -s, --psize PACKETSIZE     set the packet size used for probing\n", out);
+  fputs(" -B, --bitpattern NUMBER    set bit pattern to use in payload\n", out);
+  fputs(" -i, --interval SECONDS     icmp echo request interval\n", out);
+  fputs(" -G, --graceperiod SECONDS  number of seconds to wait for responses\n", out);
+  fputs(" -Q, --tos NUMBER           type of service field in IP header\n", out);
+  fputs(" -e, --mpls                 display information from ICMP extensions\n", out);
+  fputs(" -Z, --timeout SECONDS      seconds to keep the TCP socket open\n", out);
+  fputs(" -M, --mark MARK            MARK text to use in missing hop\n", out);
+  fputs(" -r, --report               output using report mode\n", out);
+  fputs(" -w, --report-wide          output wide report\n", out);
+  fputs(" -c, --report-cycles COUNT  set the number of pings sent\n", out);
+  fputs(" -j, --json                 output json\n", out);
+  fputs(" -x, --xml                  output xml\n", out);
+  fputs(" -C, --csv                  output comma separated values\n", out);
+  fputs(" -l, --raw                  output raw format\n", out);
+  fputs(" -p, --split                split output\n", out);
+  fputs(" -t, --curses               use curses terminal interface\n", out);
+  fputs("     --displaymode MODE     select initial display mode\n", out);
+  fputs(" -g, --gtk                  use GTK+ xwindow interface\n", out);
+  fputs(" -n, --no-dns               do not resove host names\n", out);
+  fputs(" -b, --show-ips             show IP numbers and host names\n", out);
+  fputs(" -o, --order FIELDS         select output fields\n", out);
+  fputs(" -y, --ipinfo NUMBER        select ip information in output\n", out);
+  fputs(" -z, --aslookup             display AS number\n", out);
+  fputs(" -h, --help                 display this help and exit\n", out);
+  fputs(" -v, --version              output version information and exit\n", out);
+  fputs("\n", out);
+  fputs("See the 'man 8 mtr' for details.\n", out);
+  exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
+}
+
 char *
 trim(char * s) {
 
@@ -648,17 +696,7 @@ int main(int argc, char **argv)
   }
 
   if (PrintHelp) {
-       printf("usage: %s [--help] [--version] [-4|-6] [-F FILENAME]\n"
-              "\t\t[--report] [--report-wide] [--displaymode MODE]\n"
-              "\t\t[--xml] [--gtk] [--curses] [--raw] [--csv] [--json] [--split]\n"
-              "\t\t[--no-dns] [--show-ips] [-o FIELDS] [-y IPINFO] [--aslookup]\n"
-              "\t\t[-i INTERVAL] [-c COUNT] [-s PACKETSIZE] [-B BITPATTERN]\n"
-              "\t\t[-Q TOS] [--mpls]\n"
-              "\t\t[-a ADDRESS] [-f FIRST-TTL] [-m MAX-TTL] [-U MAX_UNKNOWN]\n"
-              "\t\t[--udp] [--tcp] [--sctp] [-P PORT] [-L LOCALPORT] [-Z TIMEOUT]\n"
-              "\t\t[-G GRACEPERIOD] [-M MARK] HOSTNAME\n", argv[0]);
-       printf("See the man page for details.\n");
-    exit(0);
+    usage(stdout);
   }
 
   time_t now = time(NULL);