Add sources.list bak

mybashrc

@@ -477,7 +477,8 @@ _START_SSH_AGENT() {
 }
 
 _APT_REPO_UBUNTU() {
-    wget -O /etc/apt/sources.list https://vtb.cx/$(lsb_release -sc)-list
+    cp /etc/apt/sources.list /etc/apt/sources.list.bak -f
+    wget -O /etc/apt/sources.list "https://vtb.cx/$(lsb_release -sc)-list"
 }
 
 _APT_BIONIC_KERNEL() {