1 files changed, 33 insertions, 2 deletions

diff --git a/addts.c b/addts.c
index 07fae4f..92f7e86 100644
--- a/addts.c
+++ b/addts.c
@@ -1,3 +1,19 @@
+/* This file is part of addts
+ * Copyright (C) 2018, 2019 Sergey Poznyakoff
+ * 
+ * Addts 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, or (at your option)
+ * any later version.
+ * 
+ * Addts 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 addts.  If not, see <http://www.gnu.org/licenses/>.
+ */
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -50,6 +66,22 @@ alpha(int c)
         return c == '\n' ? AEOL : ACHR;
 }
 
+static void
+help(char *progname)
+{
+        printf("Usage: %s [OPTION]... [FILE]\n", progname);
+        puts("add timestamps at the beginning of each line\n");
+        puts("  -a                 append to FILE, instead of overwriting it");
+        puts("  -f FORMAT          strftime(3) format for timestamps");
+        puts("  -s                 add timestamp to the end of each line");
+        puts("  -u                 report times in UTC");
+        puts("  -w CHR             replace CHR with a horizontal space in FORMAT");
+        putchar('\n');
+        printf("Default FORMAT is \"%s\"\n", default_fmt);
+        putchar('\n');
+        puts("Report bugs to <gray@gnu.org>");
+}
+
 int
 main(int argc, char **argv)
 {
@@ -85,8 +117,7 @@ main(int argc, char **argv)
                         break;
                 default:
                         if (optopt == 0) {
-                                printf("usage: %s [-asu] [-f FMT] [OUT-FILE]\n",
-                                       argv[0]);
+                                help(argv[0]);
                                 return 0;
                         }
                         return 1;