POSIX-ify latest commit

subs

@@ -63,7 +63,16 @@ gen_links() {
 
         # otherwise we are given a username, we must find out its channel ID
         curl -sfL --retry 10 "https://youtube.com/user/$line/about" | \
-		echo "https://youtube.com/feeds/videos.xml?channel_id=$(grep -ohm 1 'channel\/UC......................' | tail -c 25)" >>"$SUBS_LINKS"
+        while read -r line ; do
+            case $line in
+                *channel/UC??????????????????????*)
+                    line=${line##*channel/}
+                    line=${line%%\"*}
+                    printf 'https://youtube.com/feeds/videos.xml?channel_id=%s\n' \
+                        "$line" >>"$SUBS_LINKS"
+                    break
+            esac
+        done
 
     done <"$SUBS_FILE"
 }