private static void checkPid(int pid) {
    if (pid <= 0) {
      throw new IllegalArgumentException(
          String.format("Should not send a signal to pid %s",
              pid));
    }
  }
Checks to make sure that we are operating on a valid process id. Sending signals to processes
with <code>pid</code> 0 or -1 can have unintended consequences.

@throws IllegalArgumentException If <code>pid</code> is not positive

@since GemFire 4.0
geode-logging/src/main/java/org/apache/geode/logging/internal/OSProcess.java