better detection of where the script actually resides

ezmlm-export-subscribers.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-cd $(dirname $0)
+cd "$(dirname "$(readlink -f "$0")")"
 
 # Test if config.cfg exists and set needed variables
 if [ ! -e config.cfg ]; then echo "Missing config.cfg file. Edit and rename config.cfg.sample"; exit 1; fi