diff --git a/.linux/bash/module/vdl.sh b/.linux/bash/module/vdl.sh
index 46cb891..cc30475 100644
--- a/.linux/bash/module/vdl.sh
+++ b/.linux/bash/module/vdl.sh
@@ -1,30 +1,25 @@
-# download video from URL in background.
+# Download video from URL in background. When no [LINK] specified, it tries to update previously downloaded link.
+# Usage: vdl [LINK]
 vdl()
 {
-  echo "$@" > src.txt
-  yt-dlp -f 'bestvideo[height<=?1081]+bestaudio/best' --download-archive index.txt --embed-thumbnail --embed-subs --write-auto-subs --embed-metadata --merge-output-format mkv -cio '%(playlist_index)000006d_%(id)s.%(ext)s' "$@"
+  local target="${@}" # What to download/update.
+
+  # If no [LINK] provided, try to read from `src.txt`.
+  [[ "${target}" = "" ]] && target="$(cat src.txt)" 
+
+  # If could not get [LINK] eventually, show an error and exit.
+  if [[ "${target}" = "" ]]; then
+    echo -e "${color_red}Could not determine [LINK] to download.${color_default}"
+    echo "Usage: vdl [LINK]"
+    return 1
+  fi
+
+  # Save [LINK] for later use.
+  echo "${target}" > src.txt
+
+  # Download [LINK] content.
+  yt-dlp -f 'bestvideo[height<=?1081]+bestaudio/best' --download-archive index.txt --embed-thumbnail --embed-subs --write-auto-subs --embed-metadata --merge-output-format mkv -cio '%(playlist_index)000006d_%(id)s.%(ext)s' "${target}"
 }
 
 # download all videos from file.
 alias vdl_file="vdl -a"
-
-# update playlist.
-vdl_update()
-{
-  local src="$(cat src.txt)"
-  vdl "$src"
-}
-
-# update all playlists recursively.
-vdl_update_all()
-{
-  local root="$PWD"
-  local dir
-  for file in **/src.txt; do
-    dir="${file%/*}"
-    cd "$dir"
-    echo "$PWD"
-    vdl_update
-    cd "$root"
-  done
-}