Add help message

optipdf

@@ -1,6 +1,41 @@
 #!/bin/bash
 # vi: et sts=4 sw=4 ts=4
 
+USAGE() {
+    printf 'Usage: %s [OPTIONS] [--] FILE...\n' \
+        "${0##*/}"
+}
+
+HELP_MESSAGE() {
+    USAGE
+    cat <<EOF
+Optimize PDF files for size.
+
+  --help, -h        Show this help message.
+  --backup=SUFFIX   Keep a backup of un-optimized PDF files.
+  --no-backup       Turn off backups (default).
+  --careful         Stop if there are warnings in the PDF (default).
+  --no-careful      Don't stop if there are warnings in the PDF.
+  --force, -f       Force overwriting backups. No effect if --no-backup.
+  --no-force        Prompt when overwriting backups (default). No effect if
+                      --no-backup.
+  --lossy           Let qpdf(1) try to optimize images for size. MAY LEAD TO
+                      IMAGE QUALITY DEGRADATION. See qpdf(1) for more
+                      information.
+  --no-lossy        Don't optimize images (default). This is safer.
+  --preserve-timestamp     Copy timestamp from original file.
+  --no-preserve-timestamp  Omit timestamp from original file (default).
+  --                Terminate options list.
+
+Copyright (C) 2021 Dan Church.
+License GPLv3: GNU GPL version 3.0 (https://www.gnu.org/licenses/gpl-3.0.html)
+with Commons Clause 1.0 (https://commonsclause.com/).
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+You may NOT use this software for commercial purposes.
+EOF
+}
+
 PRESERVE_TIMESTAMP=0
 LOSSY=0
 KEEP_BACKUP_SUFFIX=
@@ -49,6 +84,10 @@ for ARG; do
             --no-preserve-timestamp)
                 PRESERVE_TIMESTAMP=0
                 ;;
+            --help|-h)
+                HELP_MESSAGE
+                exit 0
+                ;;
             --)
                 NO_MORE_FLAGS=1
                 ;;