Check file rather than directory

src/freedombone-utils-backup

@@ -308,8 +308,8 @@ function backup_database_to_usb {
     database_name=$1
     local_database_dir=/root/temp${1}data
     backup_database_local ${database_name}
-    if [ ! -d ${local_database_dir} ]; then
-        echo $"Error backing up ${1} database to ${local_database_dir}"
+    if [ ! -f ${local_database_dir}/${1}.sql ]; then
+        echo $"Error backing up ${1} database to ${local_database_dir}/${1}.sql"
         exit 62383
     fi
     backup_directory_to_usb ${local_database_dir} ${database_name}data