[HECnet] PyDECnet setup

[Thomas DeBellis]

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sonic.net/pipermail/hecnet-list/attachments/20211118/90135662/attachment.htm>