audacious backup mp3 file

#!/bin/bash

function set_win_on_top() {
    pid=$1
    sleep 0.2
    win_id=`wmctrl -l -p | grep ${pid} | awk '{print $1}'`
    wmctrl -i -r ${win_id} -b add,above 2>/dev/null
}

function audacious_copy_song() {
    curent_song_loc=$(audtool current-song-filename)
    file_name="${curent_song_loc##*/}"
    file_extension="${file_name##*.}"
    file="${file_name%.*}"
    dest_song_loc=$(echo ~/Music/$file_name)
    if [ -f "$dest_song_loc" ]; then
        unique_file_name=$file"_"$(date +%s%N)"."$file_extension
        unique_dest_song_loc=$(echo ~/Music/$(echo $unique_file_name))
        cp "$(echo $curent_song_loc)" "$(echo $unique_dest_song_loc)"
        zenity --notification --text "file copied:\r\n$unique_file_name"
    else
        cp "$(echo $curent_song_loc)" "$(echo ~/Music)"
        zenity --notification --text "file copied:\r\n$file_name"
    fi
}

audacious_copy_song & set_win_on_top $!