[HECnet] PyDECnet setup

[Thomas DeBellis]

Well, I don't remember Ultrix or SunOS doing this when I was one of 
Columbia's Unix Systems Programmers.  However, that might mean exactly 
nothing more than I don't remember and that they did do it.  I don't 
remember it in any daemon that I developed.  Of course, I can barely 
remember any daemon I developed...

My dissatisfaction is not with the practice itself so much as what winds 
up being called a standard and who says it is.  Until somebody says 
different...

On 11/18/21 11:43 AM, Dave McGuire wrote:
>
>   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
>
>