Fix drive detection

install.sh

@@ -45,7 +45,9 @@ if [ $disk_base == "manual" ]; then
     echo "[?] Good luck! Type exit to return to the installer."
     zsh
 else
-    if [ ! -f $disk_base ]; then
+    ls $disk_base > /dev/null
+
+    if [ $? != 0 ]; then
         echo "[!] Device $disk_base does not exist."
         exit 1
     fi