* @param val - string containing command to be executed
*/
public void processShellCmd(String key, String val, Boolean overwrite) throws ParameterSubstitutionException, FrontendException {
if (pigContext != null) {
BlackAndWhitelistFilter filter = new BlackAndWhitelistFilter(pigContext);
filter.validate(PigCommandFilter.Command.SH);
}
if (param_val.containsKey(key)) {
if (param_source.get(key).equals(val) || !overwrite) {
return;