Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

So, in studying for the LPI Certification, and doing some practice exams, I keep running into questions that I get wrong simply because I assume the HUP signal is equivalent to restarting a service/daemon. Obviously, I'm wrong, but can someone enlighten me as to why?

The Apache documentation states that HUP kill off the process' children, but not the parent, which sense, but is this behaviour mimicked in unix?

share|improve this question

1 Answer 1

up vote 5 down vote accepted

The usual effect of HUP on long-running daemons is to reload the configuration. Sometimes this is done by restarting completely, sometimes something more intelligent/fast/safe is done.

There is nothing mandatory about this behavior, it's not really what that signal was intended for originally. (The SIGHUP article on Wikipedia has a bit more details.)

Each daemon's writer is free to implement SIGHUP handling as he/she wishes. This includes ignoring the signal entirely.

share|improve this answer
    
Thanks for the extra information! :) –  Julian H. Lam Apr 3 '11 at 17:18

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.