Unify shell script style

bin/invidious.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-# env
+# invidious
 # Written in 2019 by Leslie
 # Modified in 2019 by Lucas
 # CC0 1.0 Universal/Public domain - No rights reserved
@@ -11,20 +11,25 @@
 # Dedication along with this software. If not, see
 # <http://creativecommons.org/publicdomain/zero/1.0/>.
 
-usage() {
+usage()
+{
 	printf "Usage: %s url\n" "${0##*/}" >&2
 	exit 1
 }
 
-if [ $# -ne 1 ]; then
-	usage
-fi
+err()
+{
+	printf "%s: %s\n" "${0##*/}" "$*" >&2
+	exit 1
+}
+
+[ $# -eq 1 ] || usage
 
 case $1 in
 "https://invidio.us/watch?v="*)
 	;;
-*)	printf "%s: Not an invidio.us url.\n" "${0##*/}" >&2
-	exit 1
+*)	err "Not an invidio.us url."
+	;;
 esac
 
 video_id=
@@ -34,21 +39,17 @@ for param in $(printf "%s\n" "${1##*"?"}" | tr "&" "\n"); do
 
 	v=${param#*=}
 	if [ ${#v} -ne 11 ]; then
-		printf "%s: "%s": not a video id.\n" "${0##*/}" "$v" >&2
+		printf  "%s: \"%s\": not a video ID." "${0##*/}" "$v" >&2
 		continue
 	fi
 	video_id=$v
 	break
 done
 
-if [ -z "$video_id" ]; then
-	printf "%s: no video ID in URL.\n" "${0##*/}" >&2
-	exit 1
-fi
+[ -n "$video_id" ] || err "no video ID in URL."
 
-dl_option=$(ftp -o - "$1" 2>/dev/null \
-    | grep "<option value='{" \
-    | head -n 1 | cut -d "\"" -f 8)
+dl_option=$(ftp -o - "$1" 2>/dev/null | grep -F "<option value='{" |
+    head -n 1 | cut -d "\"" -f 8)
 
 printf "https://invidio.us/latest_version?id=%s&itag=%s\n" \
     "$video_id" "$dl_option"