[HECnet] PyDECnet setup

[Dave McGuire]

   Tom, you're describing "proper 1970s UNIX fashion".  A SIGHUP to 
reload/reconfigure a running process has been standard since the 
mid/late 1980s, perhaps even earlier.

            -Dave

On 11/18/21 10:50 AM, Thomas DeBellis 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


-- 
Dave McGuire, AK4HZ
New Kensington, PA