[HECnet] PyDECnet setup

[Paul Koning]

Maybe I'm referring to something that doesn't go all the way back to early Unix.  But at least in Linux as far back as I can remember -- certainly back to late last century -- sending SIGHUP to a daemon has been the standard way to say "reload your configuration".  In the startup managers, a reload command applied to a particular daemon's entry acts by sending that signal.

	paul

> On Nov 18, 2021, at 10:50 AM, Thomas DeBellis <tommytimesharing at gmail.com> wrote:
> 
> The statement, "Proper Unix fashion", leaves me somewhat uncomfortable.
> 
> Since I'm ancient, my understanding of SIGHUP is to handle a hangup detected on the controlling terminal or the death of a controlling process.  A hangup started out meaning dropping carrier on a modem or DTR on a hardwired line.  It came to include a broken network terminal connection.
> 
> When I think of how to handle a SIGHUP, I usually think of 'gracefully' stopping a process (I.E., saving the user's work instead of ditching it) and exiting.  If you don't do that, then something else has to be used to get rid of you, perhaps a SIGTERM.  The problem is that if somebody wants you gone and you don't go away, you have a 9 on your hands (SIGKILL).  Now that data is gone.
> 
> If you usurp SIGHUP for such use, then things like NOHUP won't do the expected thing.  There are certainly reasons to be NOHUP'ed.  In your superior breaks, you might not want to disappear so somebody has a chance to attach a debugger to you to try to figure out what happened.
> 
> I think the better thing to do would be handle a SIGUSR1/SIGUSR2 to reparse.
> 
> Of course, "proper" is a very relative term in Unix.  Things change and sometimes get used for no readily apparent reason, the result being that an unspoken 'standard' happens.  It is not uncommon.  For example, Johnny's DECnet bridge does in fact use SIGUSR1 to display some information.  However, it uses a SIGHUP to do a reparse.  So maybe that's the best of both worlds...
> 
> I've never felt strongly enough about the matter to suggest SIGUSR2 for a reparse, but if you want to be a purist, then it probably should.
>> 
>> On 11/18/21 9:58 AM, Paul Koning wrote:
>> 
>> 
>> In proper Unix fashion it could be triggered by a SIGHUP signal

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