public static void shutDownAll(ArrayList<String> cmdLine) {
    try {
      long timeout = 0;
      if (cmdLine.size() > 0) {
        timeout = Long.parseLong(cmdLine.get(0));
      }
      InternalDistributedSystem ads = getAdminCnx();
      Set members =
          AdminDistributedSystemImpl.shutDownAllMembers(ads.getDistributionManager(), timeout);
      int count = members == null ? 0 : members.size();
      if (members == null) {
        System.err
            .println("Unable to shut down the distributed system in the specified amount of time.");
      } else if (count == 0) {
        System.err.println("The distributed system had no members to shut down.");
      } else if (count == 1) {
        System.out.println("Successfully shut down one member");
      } else {
        System.out.println("Successfully shut down " + count + " members");
      }
    } catch (Exception ex) {
      throw new GemFireIOException(ex.toString(), ex);
    }
  }
Tails the end of the locator's log file

@since GemFire 4.0
geode-core/src/main/java/org/apache/geode/internal/SystemAdmin.java