import org.apache.jmeter.gui.GuiPackage;
import org.apache.commons.io.FilenameUtils;
String testPlanFile = GuiPackage.getInstance().getTestPlanFile();
String testPlanFileDir = FilenameUtils.getFullPathNoEndSeparator(testPlanFile).replace('\\', '/');
vars.put("currentDIR", testPlanFileDir+"/");